First complete description of the dark-mouth skate Raja arctowskii Dollo, 1904 from Antarctic waters, assigned to the genus Bathyraja (Elasmobranchii, Rajiformes, Arhynchobatidae)

Abstract

The dark-mouth skate, Raja arctowskii Dollo, 1904 from Antarctic waters is an extraordinary case in skate taxonomy. For more than 100 years, this species has been known only from three empty egg capsules and the species as such has remained undescribed due to the lack of specimens that could be assigned to Dollo’s small capsules. Since trawled egg capsules and an egg capsule containing a near-term embryo became available, it finally was possible to connect specimens with the empty egg capsules and completely describe Dollo’s R. arctowskii with detailed external morphology, skeletal features, clasper morphology, and clasper skeleton and assign it to the genus Bathyraja Ishiyama, 1958a. Bathyraja arctowskii is one of the smallest known species of Bathyraja, attaining only a 61 cm total length (TL). It is characterized by an at least partly, usually completely medium to dark grayish pigmented mouth cavity, as well as the often dark underside of the nasal curtain from very small juvenile stages onwards. It further differs from most congeners in Antarctic and Subantarctic waters in the absence of thorns on the dorsal disc. It appears to be a wide-ranging, circumantarctic species found in the Atlantic, Pacific, and Indian Ocean sectors of the Southern Ocean. The species seems to be locally common at least in the Atlantic sector, with up to 94 juvenile to subadult specimens caught in one single haul.

Full text

ORIGINAL PAPER
First complete description of the dark-mouth skate
Raja arctowskii Dollo, 1904 from Antarctic waters, assigned to the genus
Bathyraja (Elasmobranchii, Rajiformes, Arhynchobatidae)
Matthias F. W. Stehmann
1
&Simon Weigmann
2,3
&Gavin J. P. Naylor
4
Received: 9 April 2020 /Revised: 3 October 2020 / Accepted: 14 October 2020
#Senckenberg Gesellschaft für Naturforschung 2021
Abstract
The dark-mouth skate, Raja arctowskii Dollo, 1904 from Antarctic waters is an extraordinary case in skate taxonomy. For more
than 100 years, this species has been known only from three empty egg capsules and the species as such has remained
undescribed due to the lack of specimens that could be assigned to Dollo’s small capsules. Since trawled egg capsules and an
egg capsule containing a near-term embryo became available, it finally was possible to connect specimens with the empty egg
capsules and completely describe Dollo’sR. arctowskii with detailed external morphology, skeletal features, clasper morphology,
and clasper skeleton and assign it to the genus Bathyraja Ishiyama, 1958a.Bathyraja arctowskii is one of the smallest known
species of Bathyraja, attaining only a 61 cm total length (TL). It is characterized by an at least partly, usually completely medium
to dark grayish pigmented mouth cavity, as well as the often dark underside of the nasal curtain from very small juvenile stages
onwards. It further differs from most congeners in Antarctic and Subantarctic waters in the absence of thorns on the dorsal disc. It
appears to be a wide-ranging, circumantarctic species found in the Atlantic, Pacific, and Indian Ocean sectors of the Southern
Ocean. The species seems to be locally common at least in the Atlantic sector, with up to 94 juvenile to subadult specimens
caught in one single haul.
Keywords Systematics .Taxonomy .Morphology .DNA analysis .Egg capsules .Southern Ocean
Introduction
Raja arctowskii Dollo, 1904 is an extraordinary case in skate
taxonomy, because it was named based only on three empty
egg capsules of very small size from off the Antarctic
Peninsula, but the species as such remained undescribed due
to lack of specimens which could be assigned to Dollo’ssmall
egg capsules.
In “Fishes of the Southern Ocean”, Stehmann and Bürkel
(1990: 88, 94) mentioned, keyed out and commented on a
Bathyraja sp., which appeared to be the most abundant skate
species in the Atlantic sector of Antarctic waters, primarily in
the Weddell Sea. A specific account was not given by
Stehmann and Bürkel (1990) due to its unresolved nomencla-
torial status. Stehmann (1985: 209) had briefly commented on
a few external characteristics of this species as Bathyraja sp. 2
and underlined its small size of 60 cm maximum total length,
as compared with other Southern Ocean skate species.
The first reference to the species after Dollo (1904)wasby
Bigelow and Schroeder (1965) describing a mature male of
490 mm TL from northeast off the South Shetland Islands at
Matthias F. W. Stehmann and Simon Weigmann contributed equally to
this work.
This article is a contribution to the Topical Collection Systematics and
Biodiversity of Indian Ocean Sharks, Rays, and Chimaeras
(Chondrichthyes)
Communicated by D. Ebert
*Matthias F. W. Stehmann
stehmann@ichthys-fisch.info
1
ICHTHYS, Ichthyological Research Laboratory and Consultant,
Hildesheimer Weg 13, 22459 Hamburg, Germany
2
Elasmo-Lab, Elasmobranch Research Laboratory, Georg-Bonne-Str.
83, 22609 Hamburg, Germany
3
Center of Natural History, University of Hamburg,
Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
4
Florida Museum of Natural History, University of Florida, Dickinson
Hall, 1659 Museum Road, Gainesville, FL 32611, USA
Marine Biodiversity (2021) 51:18
https://doi.org/10.1007/s12526-020-01124-1

220–240 m depth, and a female of 258 mm TL from northeast
off Clarence Island at 585–595 m depth as Breviraja
griseocauda (Norman, 1937); both specimens were captured
by USNS “Eltanin.”The second reference was by Springer
(1971) describing a mature male of 485 mm TL as
B. griseocauda captured by RV “Hero”in 1969 off Brabant
Island north of the Antarctic Peninsula in a 94 m depth.
Authors of both papers did not recognize the very small size
of their mature males, as compared with the much larger
B. griseocauda in the SW Atlantic, of which, however, they
compared only with Norman’s(1937) holotype female of
460 mm TL plus five males of 250–332 mm TL at BMNH
London and apparently overlooked their immature juvenile
stage. Springer (1971: 7), however, commented on Raja
arctowskii Dollo, 1904 and its original only 60 mm long egg
capsules but failed to relate this small capsule size to the small
size of Bigelow and Schroeder’s(1965) and his small mature
males of his B. griseocauda and considered R. arctowskii a
nomen dubium.
Since the 1970s, many specimens of a very small
Bathyraja-like skate were captured and preserved by
German Antarctic expeditions primarily in the Weddell Sea
and off Atlantic Antarctic islands north of Antarctic Peninsula,
e.g., South Shetlands. The small size of mature males sampled
focused our attention on Raja arctowskii and its small egg
capsules, but to prove the identity required a mature female
containing egg capsules. Although such a female became
available, it was not found for the present study and other
evidence was needed, which was found in an egg capsule
containing a male near-term embryo. Based on this evidence,
we could finally prove the identity with Dollo’sR. arctowskii,
as briefly indicated by Weigmann (2016).
We are presenting here the so far lacking complete descrip-
tion and new generic assignment of Bathyraja arctowskii
(Dollo, 1904) with detailed external morphology, skeletal fea-
tures, clasper morphology and clasper skeleton. Finally, the
valid status of this small Antarctic skate species could be
confirmed.
Material and methods
Institutional acronyms follow Sabaj (2019). External morpho-
metric measurements were taken by vernier caliper to one-
tenth of a millimeter (mm) from the specimens preserved in
70% ethanol. Measurements were taken between perpendicu-
lar lines where relevant and largely following Bigelow and
Schroeder (1953). Exceptions: prenasal snout length from
snout tip to transverse line through anterior edge of nostrils,
and orbit plus spiracle length after Clark (1926); ventral head
length from snout tip to transverse line through fifth gill slits,
clasper length, and eyeball horizontal diameter after Ishiyama
(1958a); dorsal head length medially from snout tip to
occipital joint, as well as tail and nasal curtain measurements
after Hubbs and Ishiyama (1968); spiracle length measured
diagonally as depression and as aperture proper; length of
pelvic lobes measured from point of articulation of anterior
lobe according to Stehmann (1985); width across pelvic-fin
base between anterior points of articulation, anterior pelvic
lobe base width, width across posterior pelvic lobe as maxi-
mum width across expanded lobe, head width at anterior mar-
gin of orbits, as well as disc and preorbital snout length direct
(point-to-point) after Last and Séret (2008). Measurements of
egg capsules were taken after Treloar et al. (2006), Ebert and
Davis (2007), and Concha et al. (2009,2012). The following
measurements are newly introduced in this paper: central body
length excluding aprons (CBL), central body width excluding
lateral keels (CBW), as well as anterior and posterior horn
lengths measured horizontally between perpendicular lines.
Terminology of clasper glans components and skeleton
cartilages follows Hulley (1970,1972)andStehmann
(1970). Skeletal morphometric measurements of cranium
and scapulocoracoid were made after McEachran and
Compagno (1979), with postoccipital length of jugal arches
measured from level posterior edge of cranium to posterior
end of jugal arches, and of pelvic girdle after Stehmann
et al. (2008); vertebral counts follow Springer and Garrick
(1964) and Krefft (1968a). Skeletal morphometric measure-
ments and meristics were taken and counted from radiographs
except for measurements of scapulocoracoid taken from dis-
sected elements. Subantarctic and Antarctic waters are treated
as Southern Ocean herein following common practice and a
draft for amending the ocean limits by the International
Hydrographic Organization (IHO). Nevertheless, the IHO of-
ficially still recognizes only four oceans, i.e., the Indian,
Pacific, Atlantic, and Arctic oceans and any drafts that have
been circulated have no authority as a reference source (see
Weigmann 2016 for further details). The cartographic base
used for the location map is from the Quantarctica package
(Matsuoka et al. 2018).
Molecular data
Tissue samples stored in 95% alcohol associated with voucher
specimens held at the Te Papa Tongarewa Museum of New
Zealand were sent to GJPN. DNA was extracted using the
E.Z.N.A Tissue DNA Kit (Omega Bio-Tek, Inc. Norcross,
GA). Total DNA was then subjected to PCR amplification
of the mitochondrial NADH2 using primers described in
Naylor et al. (2005). Amplified fragments were cleaned and
sent out to Retrogen (6645 Nancy Ridge Drive, San Diego, Ca
9212) for bi-directional sequencing. Resulting DNA se-
quences were edited using Geneious® Pro v. 6.1.7
(Biomatters Ltd. Auckland, New Zealand, available at http://
www.geneious.com). The edited sequences were translated to
amino acids and aligned with corresponding NADH2
18 Page 2 of 27 Marine Biodiversity (2021) 51:18

sequences from representatives of available closely related
species occurring in the region using the MAFFT module
within the Geneious Package (Biomatters Ltd. Auckland,
New Zealand). The aligned amino acid sequences were
translated back, in frame, to their original nucleotide
sequences, to yield a nucleotide alignment. The alignment
was subjected to a maximum likelihood analysis using the
General Time Reversible model with rate categories
optimized to fit the data and additional parameters to
accommodate among site rate heterogeneity the proportion
of invariant sites (GTR+I+G). Phylogenetic analyses were
conducted using the software package PAUP*4.0a build 168).
Results
Systematic account
Bathyraja arctowskii Dollo, 1904
(Antarctic dark-mouth skate)
(Figs. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 1, 17, 18,
19, 20, 21, 22, 23, 24, 25, and 26, Tables 1,2,3,4,5,6,and7)
Raja arctowskii Dollo, 1904―Poissons in: Expédition
Antarctique Belge 1897–99 Zoologie, Antwerpen 1904: 11,
51, 52, plate IX, Fig. 10. Types: three empty egg capsules
IRSNB 25 [orig. 3005], IRSNB 26 [orig. 3006], IRSNB 27
[orig. 3007]; Weigmann (2016:953).
Breviraja griseocauda (not Norman, 1937)―Bigelow &
Schroeder (1965:R43–R46, Fig. 4).
Bathyraja griseocauda (not Norman, 1937)―Springer
(1971:5–7, Figs. 2 and 4B).
Bathyraja n. sp. (dwarf)―Hanchet et al. (2013:621,631).
Bathyraja sp. 2―Stehmann (1985:209);Jonesetal.
(2009: 53, 54, 63 [erroneously as Bathydraco sp. 2], 64);
Kalisz (2013:4–24).
Bathyraja sp.―Stehmann & Bürkel (1990: 88, 94).
Bathyraja sp. (dwarf)―Smith et al. (2008:1170–73,
1175–78).
Primary material examined in detail (11 specimens):
ZMH 120216 (ex ISH 489-1981), 1 adult male, 533 mm
TL, 60° 51′S, 55° 34′W, 18.03.81, 280–294 m depth (taken
together with 1 female and 1 juvenile male listed under addi-
tional material); ZMH 123230 (ex ISH 210-1987), 1 adult
female, 535 mm TL, 61° 07′S, 55° 53′W, 30.10.87, 126–
149 m depth (taken together with 3 further females listed
under additional material); ZMH 114702 (ex ISH 753-
1976), 1 subadult female, 427 mm TL, 61° 53′S, 58° 53′
W, 29.01.76, 200 m depth; ZMH 121822 (ex ISH 37-1984),
1subadultmale,424mmTL,2juvenilemales246mmTL
and 181 mm TL, 4 juvenile females 333 mm TL, 236 mm TL,
163 mm TL, and 135 mm TL, 61° 11′S, 56° 12′W, 13.11.83,
375 m depth (taken together with 87 further specimens listed
under additional material); ZMH 9014, 1 near-term male
embryo taken from egg capsule, 120 mm TL, 61° 13.9′S,
56° 25.4′W, 21.11.96, 403–415 m depth.
Additional material, only partially examined (267
specimens): MNHN 1987-0232, adult male, 591 mm TL,
Prydz Bay, 66° 59′24″S, 73° 52′52″E, 26.01.85, 475 m
depth (morphometrics, meristics and description notes kindly
provided for this specimen by Bernard Séret, photographs and
radiographs by Jonathan Pfliger, Guy Duhamel and Zouhaira
Gabsi); USNM 204703, late subadult male, 477 mm TL, 64°
12.1S, 62° 40′W, 09.02.1969, 94 m depth; ZMH 114623 (ex
ISH 1025-1976), 1 female, 421 mm TL, 62° 39′S, 59° 51′W,
30.01.76, 200–238 m depth; ZMH 114650 (ex ISH 1027-
1976), 1 female, 358 mm TL, 61° 39′S, 57° 36′W,
28.01.76, 400 m depth; ZMH 114695 (ex ISH 771-1976), 1
female, 394 mm TL, 61° 39′S, 57° 36′W, 28.01.76, 400 m
depth; ZMH 114696 (ex ISH 767-1976), 1 juvenile male,
342 mm TL, 60° 49′S, 55° 37′W, 27.01.76, 300–350 m
depth; ZMH 114701 (ex ISH 754-1976), 1 juvenile female,
234 mm TL, 62° 05′S, 60° 16′W, 29.01.76, 306 m depth;
ZMH 115002 (ex ISH 1026-1976), 1 juvenile female,
139 mm TL, 60° 49′S, 55° 42′W, 24.02.76, 345–405 m
depth; ZMH 115009 (ex ISH 1028-1976), 5 juvenile females,
250, 263, 291, 197, and 309mm TL, 4 juvenile males 303,
304, 308, and 355 mm TL, 60° 24′S, 45° 40′W, 15.02.76,
400 m depth; ZMH 115022 (ex ISH 757-1976), 1 female,
355 mm TL, 60° 50′S, 55° 42′W, 17.02.76, 363 m depth;
ZMH 115023 (ex ISH 756-1976), 1 male postembryo,
141 mm TL, 60° 50′S, 55° 35′W, 16.02.76, 400 m depth;
ZMH 115024 (ex ISH 755-1976), 1 juvenile male, 353 mm
TL, 65° 28′S, 67° 42′W, 05.02.76, 300 m depth; ZMH
115188 (ex ISH 299-1977), 1 female, 465 mm TL, 1 adult
male, 589 mm TL, 62° 23.5′S, 61° 12′W, 28.11.77, 235 m
depth; ZMH 115191 (ex ISH 687-1978), 1 subadult male,
392 mm TL, 1 female, 463 mm TL, 61° 13.7′S, 56° 09.9′
W, 21.11.77, 288–300 m depth; ZMH 115195 (ex ISH 693-
1978), 1 juvenile male, 248 mm TL, 60° 52′S, 55° 29.7′W,
21.11.77, 235–240 m depth; ZMH 115241 (ex ISH 685-
1978), 1 juvenile female, 339 mm TL, 2 juvenile males, 156
and 328 mm TL, 60° 25′S, 46° 39′W, 16.01.78, 300–360 m
depth; ZMH 115243 (ex ISH 689-1978), 2 juvenile males,
299 and 346 mm TL, 2 adult males, 502 and 520 mm TL, 3
adult females, 492, 510, and 535 mm TL (all damaged), 60°
53′S, 55°19′W, 24.01.78, 345–400 m depth; ZMH 115253
(ex ISH 684-1978), 1 juvenile female, 252 mm TL, 4 juvenile
males, 220+ (severely damaged), 315, 371, and 376 mm TL,
60° 49′S, 55° 44′W, 25.01.78, 478–490 m depth; ZMH
115334 (ex ISH 698-1978), 1 subadult male, 365 mm TL,
62° 01′S, 59° 58′W, 04.03.78, 225–227 m depth; ZMH
115447 (ex ISH 688-1978), 1 juvenile male, 256 mm TL, 1
adult female, 510 mm TL, 60° 50′S, 55° 36′W, 25.02.78,
211–315 m depth; ZMH 120216 (ex ISH 489-1981), 1 fe-
male, 347 mm TL, 1 juvenile male, 327 mm TL, 60° 51′S,
55° 34′W, 18.03.81, 280–294 m depth (taken together with 1
Marine Biodiversity (2021) 51:18 Page 3 of 27 18

Table 1 Bathyraja arctowskii, mophometrics and meristics. Individual
values for primary adult male, primary adult female, primary subadult
male, primary subadult female, and adult male MNHN 1987-0232*, as
well as ranges for juveniles and embryo (n= 7) and means for all 12
specimens. Proportional individual values are expressed as percentages
of total length (TL) 70% ethanol preserved; minimum, maximum, and
mean of TL are given in millimeters
Primary adult
male,
ZMH 120216
Primary adult
female with
extreme tail
tip missing,
ZMH 123230
Primary
subadult
male,
ZMH 121822
Primary
subadult
female,
ZMH 114702
Adult male,
MNHN 1987–0232
Minimum
juveniles
and
embryo
(n=7)
Maximum
juveniles
and
embryo
(n=7)
Mean all
specimens
(n=12)
mm % TL mm % TL mm % TL mm % TL mm % TL % TL % TL % TL
TL, mm 533.0 100.0 535.0 100.0 424.0 100.0 427.0 100.0 591.0 100.0 120.0 333.0 327.0
Disc, width 352.0 66.0 330.0 61.7 261.0 61.6 282.0 66.0 384.0 65.0 51.7 64.6 62.4
Disc, length 296.0 55.5 273.0 51.0 212.0 50.0 238.0 55.7 320.0 54.1 44.2 50.8 50.0
Snout length, preorbital 72.5 13.6 61.0 11.4 48.5 11.4 69.0 16.2 74.0 12.5 8.1 11.6 11.4
Snout length, preoral 67.0 12.6 61.0 11.4 47.0 11.1 64.7 15.2 75.0 12.7 8.8 11.3 11.3
Snout length, prenasal 55.5 10.4 50.5 9.4 38.7 9.1 55.0 12.9 56.0 9.5 7.4 9.4 9.2
Orbit, horizontal diameter 25.0 4.7 24.6 4.6 20.5 4.8 17.7 4.1 24.0 4.1 4.6 5.8 4.9
Eyeball, horiz. diameter 18.0 3.4 20.0 3.7 15.5 3.7 15.5 3.6 19.6 3.3 3.9 4.6 4.0
Interorbital width 19.0 3.6 16.0 3.0 13.0 3.1 13.0 3.0 21.0 3.6 3.2 3.8 3.4
Spiracle length 16.5 3.1 14.0 2.6 12.7 3.0 12.0 2.8 16.0 2.7 2.7 3.8 2.9
Interspiracular width 42.2 7.9 39.3 7.3 31.0 7.3 30.0 7.0 43.0 7.3 7.9 8.8 8.1
Orbit + spiracle length 28.5 5.3 26.0 4.9 22.0 5.2 21.0 4.9 30.5 5.2 4.9 5.9 5.2
D1, height 19.3 3.6 8.7 1.6 12.1 2.9 9.5 2.2 17.4 2.9 1.6 3.1 2.3
D1, base length 22.0 4.1 24.5 4.6 16.6 3.9 12.2 2.9 27.6 4.7 2.1 4.2 3.7
D2, height 14.5 2.7 10.0 1.9 10.5 2.5 10.0 2.3 13.5 2.3 1.6 2.3 2.0
D2, base length 13.8 2.6 21.0 3.9 14.6 3.4 12.5 2.9 19.8 3.4 2.8 4.0 3.4
Interdorsal space 0.0 0.0 1.5 0.3 3.4 0.8 3.3 0.8 2.5 0.4 0.0 1.4 0.5
C, base length 9.0 1.7 12.0 2.2 7.0 1.7 15.0 3.5 Nm Nm 1.9 5.2 2.9
C, height epichordal lobe 2.1 0.4 1.0 0.2 1.9 0.4 1.5 0.4 Nm Nm 0.2 0.5 0.3
C, height hypochordal lobe 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Tail, postdorsal length 9.0 1.7 12.0 2.2 7.0 1.7 15.0 3.5 8.0 1.4 1.9 5.2 2.7
Tail, height at V-tips 11.5 2.2 11.0 2.1 9.5 2.2 8.5 2.0 17.3 2.9 2.3 4.3 2.6
Tail, width at V-tips 17.2 3.2 20.0 3.7 15.5 3.7 15.5 3.6 24.7 4.2 3.3 4.5 3.7
Tail, height at D1-origin 4.5 0.8 4.0 0.7 3.7 0.9 4.0 0.9 5.7 1.0 0.9 1.3 1.0
Tail, width at D1-origin 11.5 2.2 10.0 1.9 7.9 1.9 6.8 1.6 11.7 2.0 1.1 2.0 1.7
Tail, lateral fold length 250.0 46.9 255.0 47.7 198.8 46.9 189.0 44.3 278.0 47.0 32.8 47.6 42.3
Head length, ventrally 149.5 28.0 133.5 25.0 109.0 25.7 119.0 27.9 165.0 27.9 21.5 25.9 25.0
Head length, dorsally 106.0 19.9 95.0 17.8 74.5 17.6 92.3 21.6 Nm Nm 14.2 18.7 17.9
Mouth width 41.0 7.7 34.5 6.4 29.0 6.8 27.3 6.4 42.0 7.1 6.5 8.4 7.3
Internarial width 35.5 6.7 34.1 6.4 25.5 6.0 28.0 6.6 41.0 6.9 6.0 7.2 6.5
Nasal curtain, length 22.0 4.1 20.0 3.7 14.5 3.4 15.5 3.6 29.0 4.9 2.4 3.4 3.5
Nasal curtain, width each lobe 12.0 2.3 12.0 2.2 9.5 2.2 9.0 2.1 16.7 2.8 2.0 2.7 2.3
Nasal curtain, space between
lobes
28.0 5.3 23.0 4.3 19.5 4.6 17.0 4.0 20.8 3.5 2.8 4.0 3.8
Gill slit length, 1st 7.2 1.4 6.5 1.2 4.3 1.0 3.2 0.7 6.3 1.1 0.7 1.4 1.1
Gill slit length, 3rd 9.2 1.7 7.5 1.4 4.9 1.2 3.8 0.9 8.3 1.4 1.1 1.6 1.3
Gill slit length, 5th 5.8 1.1 4.9 0.9 3.3 0.8 3.6 0.8 3.8 0.6 0.8 1.4 0.9
Interspac e first gill s lits 7 7.0 14.4 77.0 14.4 62.3 14.7 65.3 15.3 8 2.8 14.0 14.2 15.9 14.9
Interspace fifth gill slits 48.5 9.1 56.0 10.5 41.0 9.7 53.5 12.5 48.9 8.3 9.3 11.1 10.0
V-length, ant. Lobe 63.5 11.9 59.0 11.0 53.5 12.6 46.5 10.9 79.0 13.4 10.3 13.1 12.1
V-length, post. Lobe 103.0 19.3 73.5 13.7 75.0 17.7 69.0 16.2 127.0 21.5 11.1 18.7 16.7
Clasper, postcloaca length 137.0 25.7 –– 86.5 20.4 ––142.0 24.0 6.7 10.4 16.0
Clasper len gth 118.0 22.1 ––73.0 17.2 ––120.0 20.3 3.8 6.2 12.4
Snout tip to mid-cloaca 259.0 48.6 254.5 47.6 193.5 45.6 212.0 49.6 281.0 47.5 41.3 45.6 45.2
Snout tip to 1st hemal spine 269.5 50.6 267.0 49.9 203.5 48.0 220.0 51.5 Nm Nm 43.8 48.2 47.4
Snout tip to axis max. disc width 160.0 30.0 150.0 28.0 122.0 28.8 136.0 31.9 185.0 31.3 24.2 30.9 28.7
Mid-cloaca to D1 225.0 42.2 221.0 41.3 181.5 42.8 164.0 38.4 254.0 43.0 44.1 46.7 43.9
Mid-cloaca to D2 252.0 47.3 240.5 45.0 201.0 47.4 181.5 42.5 285.5 48.3 48.2 52.3 48.1
Mid-cloaca to tail tip 271.0 50.8 280.0 52.3 223.5 52.7 211.0 49.4 314.0 53.1 53.2 60.2 54.5
Snout angle, ° 110 112 120 112 105 125 140 123.1
Tooth rows, upper jaw 24 29 25 27 24 22 27 25.5
Tooth rows, lower jaw 24 28 27 25 25 21 29 25.7
Trunk vert., Vtr 31 32 33 37 31 30 33 32.0
Predorsal tail vert., Vprd 76 70 74 74 76 66 80 73.8
18 Page 4 of 27 Marine Biodiversity (2021) 51:18

adult male listed under primary material); ZMH 120217 (ex
ISH 491-1981), 5 juvenile females, 143, 160, 184, 205, and
212 mm TL, 4 juvenile males, 146, 159, 204, and 260 mm TL,
60° 50′S, 55° 39′W, 19.03.81, 450–470 m depth; ZMH
120223 (ex ISH 492-1981), 2 juvenile females, 243 and
245 mm TL, 2 juvenile males, 162 and 172 mm TL, 1 juvenile
male, 343 mm TL, 1 adult male, 532 mm TL, 62° 12′S, 57°
00′W, 16.03.81, 0–140 m depth; ZMH 121820 (ex ISH 41-
1984), 3 females, 385, 391, and 475 mm TL, 1 juvenile male,
267 mm TL, 1 subadult male, 416 mm TL, 61° 07′S, 56° 05′
W, 15.11.83, 235 m depth; ZMH 121821 (ex ISH 39-1984), 1
juvenile female, 232 mm TL, 1 juvenile male, 271 mm TL, 1
subadult male, 361 mm TL, 61° 06′S, 55° 59′W, 15.11.83,
177 m depth; ZMH 121822 (ex ISH 37-1984), 87 specimens,
males 141–432 mm TL, females 149–475 mm TL, 61° 11′S,
56° 12′W, 13.11.83, 375 m depth (taken together with 7
specimens listed under primary material); ZMH 122009 (ex
ISH 33-1985), 1 female, 460 mm TL, 61° 20′S, 54° 42.3′W,
10.01.85, 292 m depth; ZMH 122065 (ex ISH 172-1985), 1
subadult male, 421 mm TL, 61° 20′S, 54° 44′W, 21.02.85,
311–364 m depth; ZMH 122072 (ex ISH 176-1985), 1 fe-
male, 483 mm TL, 61° 17′S, 56° 04′W, 23.02.85, 279–288
m depth; ZMH 122075 (ex ISH 114-1985), 1 juvenile male,
285 mm TL, 1 female, 464 mm TL, 72° 53.1′S, 19° 29.3′W,
20.02.85, 423 m depth; ZMH 122079 (ex ISH 178-1985), 1
female, 368 mm TL, 61° 06′S, 56° 04′W, 24.02.85, 238–274
m depth; ZMH 122084 (ex ISH 175-1985), 1 juvenile female,
301 mm TL, 61° 12′S, 56° 09′W, 22.02.85, 301–318 m
depth; ZMH 122097 (ex ISH 167-1985), 1 juvenile male,
352 mm TL, 60° 52′S, 55° 30′W, 27.02.85, 306–310 m
depth; ZMH 122107 (ex ISH 104-1985), 1 juvenile female,
311 mm TL, 73° 23.4′S, 21° 30.5′W, 18.02.85, 475 m depth;
ZMH 122299 (ex ISH 953-1986), 1 female, 213 mm TL, 4
juvenile males, 249, 304, 305 and 317 mm TL, 60° 51′S, 55°
34′W, 11.05.86, 319–320 m depth; ZMH 122301 (ex ISH
955-1986), 3 juvenile males, 245, 290 and 331 mm TL, 1 1
juvenile female, 308 mm TL, 1 female, 332 mm TL, 61° 20′S,
55° 48′W, 13.05.86, 249–259 m depth; ZMH 122328 (ex ISH
956-1986), 2 juvenile males, 265 and 347 mm TL, 1 subadult
male, 363 mm TL, 1 female, 370 mm TL, 61° 18′S, 55° 06′
W, 13.05.86, 261–309 m depth; ZMH 122333 (ex ISH 954-
1986), 1 juvenile female, 237 mm TL, 60° 51′S, 55° 35′W,
11.05.86, 319–320 m depth; ZMH 122498 (ex ISH 959-
1986), 2 subadult males, 435 and 440 mm TL, 1 late subadult
male, 470 mm TL, 1 adult male, 520 mm TL, 60° 57′S, 55°
19′W, 10.06.86, 220–246 m depth; ZMH 122499 (ex ISH
960-1986), 1 juvenile male, 304 mm TL, 2 subadult males,
362 and 374 mm TL, 1 late subadult male, 461 mm TL, 1
juvenile female, 313 mm TL, 2 females, 351 and 445 mm TL,
60° 57′S, 55° 07′W, 10.06.86, 377–383 m depth; ZMH
122500 (ex ISH 962-1986), 1 juvenile female, 253 mm TL,
61° 06′S, 55° 57′W, 11.06.86, 143 m depth; ZMH 122510
(ex ISH 969-1986), 3 females, 243, 273 and 273 mm TL, 2
males, 223 and 275 mm TL, 61° 02′S, 55° 00′W, 13.06.86,
319–337 m depth; ZMH 122516 (ex ISH 958-1986), 1 sub-
adult male, 450 mm TL, 60° 51′S, 55° 45′W, 09.06.86, 284–
291 m depth; ZMH 122545 (ex ISH 964-1986), 1 juvenile
female, 300 mm TL, 60° 51′S, 55° 29′W, 12.06.86, 466–
493 m depth; ZMH 122546 (ex ISH 963-1986), 1 juvenile
male, 297 mm TL, 60° 51′S, 55° 27′W, 12.06.86, 334–343
m depth; ZMH 122574 (ex ISH 967-1986), 1 juvenile female,
247 mm TL, 61° 07′S, 56° 08′W, 13.06.86, 283–307 m
depth; ZMH 122575 (ex ISH 965-1986), 4 juvenile females,
187, 233, 267, and 327 mm TL, 60° 50′S, 55° 42′W,
12.06.86, 359–401 m depth; ZMH 122576 (ex ISH 968-
1986), 2 juvenile males, 139 and 255 mm TL, 61° 04′S, 56°
Table 1 (continued)
Primary adult
male,
ZMH 120216
Primary adult
female with
extreme tail
tip missing,
ZMH 123230
Primary
subadult
male,
ZMH 121822
Primary
subadult
female,
ZMH 114702
Adult male,
MNHN 1987–0232
Minimum
juveniles
and
embryo
(n=7)
Maximum
juveniles
and
embryo
(n=7)
Mean all
specimens
(n=12)
mm % TL mm % TL mm % TL mm % TL mm % TL % TL % TL % TL
Terminal vert., Vterm
(approximately)
29 29 25 40 28 23 30 27.6
Total vert., Vtotal
(approximately)
136 131 132 151 135 120 1 38 1 33.5
Pectoral rays l./r. 76/75 73/74 73/74 89/90 79/78 ~ 70/~ 70 76/77 74.9/75.1
Pelvic rays l./r. 5 + 16/
5+17
4 + 16/
4+17
4+~18/
4+~18
5 + 20/
5+19
5 + 17/5 + 18 4 + 20/4 + ~ 18 5 + 19/5 + 19 4.7 + 17/4.7 + 17
Nm not measured
*Measurements for adult male MNHN 1987-0232 were kindly provided by Bernard Séret (ICHTHYO CONSULT)
Marine Biodiversity (2021) 51:18 Page 5 of 27 18

01′W, 13.06.86, 350–369 m depth; ZMH 123066 (ex ISH
163-1987), 1 adult male, 525 mm TL, 60° 03′S, 55° 58′W,
29.10.86, 170–280 m depth; ZMH 123074 (ex ISH 166-
1987), 1 adult male, 505 mm TL, 61° 00′S, 56° 02′W,
15.11.86, 176–767 m depth; ZMH 123075 (ex ISH 167-
1987), 1 female, 394 mm TL, 60° 52′S, 55° 35′W,
16.11.86, 214–461 m depth; ZMH 123078 (ex ISH 168-
1987), 1 female, 375 mm TL, 62° 14′S, 58° 18′W,
18.11.86, 470–500 m depth; ZMH 123080 (ex ISH 165-
1987), 1 juvenile male, 195 mm TL, 62° 23′S, 55° 10′W,
14.11.86, 263–314 m depth; ZMH 123085 (ex ISH 169-
1987), 2 females, 363 and 424 mm TL, 61° 46′S, 58° 53′
W, 18.02.87, 271–282 m depth; ZMH 123089 (ex ISH 171-
1987), 2 adult males, 527 and 586 mm TL, 61° 44′S, 58° 37′
W, 18.02.87, 267–280 m depth; ZMH 123201 (ex ISH 213-
1987), 2 females, 385 and 450 mm TL, 1 late subadult male,
495 mm TL, 61° 01′S, 55° 58′W, 31.10.87, 316–359 m
depth; ZMH 123202 (ex ISH 209-1987), 4 juvenile females,
270, 272, 277 and 298 mm TL, 1 female, 372 mm TL, 1 adult
female, 529 mm TL, 61° 06′S, 56° 07′W, 30.10.87, 260–297
m depth; ZMH 123230 (ex ISH 210-1987), 1 juvenile female,
262 mm TL, 1 female, 395 mm TL, 1 adult female, 531 mm
TL, 61° 07′S, 55° 53′W, 30.10.87, 126–149 m depth (taken
together with 1 adult female listed under primary material);
ZMH 123232 (ex ISH 212-1987), 2 juvenile females, 314 and
334 mm TL, 2 females, 435 and 452 mm TL, 6 juvenile males,
309, 310, 315, 330, 330 and 335 mm TL, 1 late subadult male,
470 mm TL, 1 adult male, 495 mm TL, 61° 01′S, 56° 24′W,
30.10.87, 342–359 m depth; ZMH 123243 (ex ISH 218-
1987), 1 female, 410 mm TL, 1 adult female, 608 mm TL,
60° 55′S, 55° 24′W, 01.11.87, 238–270 m depth; ZMH
123251 (ex ISH 216-1987), 1 juvenile male, 356 mm TL, 1
adult male, 560 mm TL, 60° 51′S, 55° 34′W, 01.11.87, 300–
336 m depth; ZMH 123253 (ex ISH 215-1987), 3 juvenile
males, 232, 280 and 350 mm TL, 60° 50′S, 55° 38′W,
01.11.87, 384 m depth; ZMH 123399 (ex ISH 54-1989), 4
Table 2 Bathyraja arctowskii, morphometrics of cranium based on radiographs. Proportional values are expressed as percentages of nasobasal length
(NBL)
Primary adult male,
ZMH 120216,
533 mm TL
Primary adult female with
extreme tail tip missing,
ZMH 123230, 535 mm TL
Primary subadult
male, ZMH 121822,
424 mm TL
Primary subadult
female, ZMH 114702,
427 mm TL
mm % NBL mm % NBL mm % NBL mm % NBL
Cranium TL 117.5 192.7 99.4 187.0 71.4 181.7 85.0 216.7
Nasobasal length (NBL) 61.0 100.0 53.2 100.0 39.3 100.0 39.2 100.0
Max. ethmoidal width 58.5 95.8 55.1 103.7 40.6 103.3 38.3 97.7
Min. dorsal interorb. width 19.0 31.1 16.0 30.1 13.0 33.1 13.0 33.2
Min. internasal width 8.6 14.1 8.9 16.7 5.9 15.1 9.0 22.8
Max. width nasal apertures 24.7 40.5 20.9 39.3 14.3 36.4 13.0 33.1
Min. ventral interorb. width/basal plate width 16.4 27.0 14.3 26.9 10.7 27.3 10.4 26.5
Max. width otic region 32.4 53.2 30.4 57.1 23.6 60.0 20.3 51.7
Max. width jugular 36.4 59.7 33.7 63.3 24.8 63.2 25.3 64.6
Rostral shaft length 56.2 92.2 45.7 86.0 31.8 80.9 45.7 116.5
Rostrum base width 14.1 23.1 14.9 28.0 10.6 27.0 9.0 22.8
Postnasal length orbit region 20.9 34.2 19.2 36.2 12.6 32.0 10.9 27.9
Length otic region 17.9 29.4 14.8 27.8 11.7 29.8 15.6 39.7
Postoccipital length jugal arches 1.0 1.6 0.6 1.1 0.0 0.0 0.0 0.0
Tip rostrum to tip ant. fontanelle 51.6 84.7 41.0 77.2 28.7 73.1 44.5 113.6
Tip rostrum to end ant. fontanelle 72.4 118.6 59.6 112.1 40.2 102.2 52.9 135.0
Tip rostrum to level ant. propterygia 12.7 20.9 7.5 14.1 7.7 19.5 7.4 18.8
Tip rostrum to level max. ethmoidal width 61.9 101.5 52.9 99.5 36.3 92.3 50.4 128.5
Tip rostrum to symphysis upper jaw 68.0 111.4 61.0 114.7 41.3 105.1 55.6 141.8
Ant. fontanelle length 20.3 33.2 17.8 33.5 11.5 29.3 8.6 21.8
Ant. fontanelle max. width 11.1 18.2 13.1 24.7 8.3 21.1 9.2 23.4
Angle post. edge nasal capsules, ° 54 75 74 66
18 Page 6 of 27 Marine Biodiversity (2021) 51:18

juvenile males, 148, 151, 220 and 294 mm TL, 2 juvenile
females, 187 and 250 mm TL, 1 female postembryo,
143 mm TL (all specimens ex MNHN), 74° 37′S, 29° 36′
W, 10.02.89, 798–810 m depth; ZMH 123415 (ex ISH 25-
1989), 2 juvenile males, 326 and 371 mm TL, 2 early subadult
males, 395 and 396 mm TL, 1 juvenile female, 337 mm TL, 1
female, 487 mm TL, 74° 40′S, 29° 31′W, 03.02.89, 593–602
m depth; ZMH 123419 (ex ISH 60-1989), 1 juvenile male,
72° 55′S, 19° 49′W, 12.02.89, 602–617 m depth; ZMH
123420 (ex ISH 20-1989), 2 late juvenile males, 368 and
384 mm TL, 1 subadult male, 412 mm TL, 4 females, 330,
351, 382, and 420 mm TL, 74° 37′S, 29° 38′W, 04.02.89,
701–708 m depth.
Specimens with only collection data, few photographs
and notes, kindly provided by Andrew Stewart (n=61;
asterisk denotes specimens used for molecular analyses):
NMNZ P.036116, 1 adult specimen, 500 mm TL, 71°
43.0000′S, 177° 7.8000′E, 08 Feb 1999, 870–940 m depth;
NMNZ P.036132, 1 male postembryo, 165 mm TL, 72°
23.1000′S, 175° 58.1000′E, 09 Feb 1999, 772–986 m depth;
NMNZ P.036182, 1 adult specimen, 570 mm TL, 72°
12.3000′S, 178° 36.0500′W, 06 Feb 1999, 773–801 m depth;
NMNZ P.036184, 2 adult specimens, 531 and 582 mm TL,
71° 30.000′S, 177° 0.000′E, 1999; NMNZ P.037551, 1 adult
female, 610 mm TL, 71° 56.900′S, 176° 34.0000′W, 01
Feb 2000, 809–848 m depth; NMNZ P.037552, 1 adult male,
565 mm TL, 71° 54.650′S, 178° 4.0000′W, 08 Feb 2000,
770–809 m depth; NMNZ P.037554, 1 adult male, 551 mm
TL, 71° 53.200′S, 178° 9.0000′W, 06 Feb 2000, 799–851 m
depth; NMNZ P.037786, 1 adult male, 571 mm TL, 71°
3.00000′S, 179° 39.00000′E, 12 Mar 2001, 1178–1374 m
depth; NMNZ P.037794, 1 adult female, 604 mm TL, 71°
28.000′S, 176° 46.000′E, 17 Feb 2001, 1200 m depth;
NMNZ P.038600, 1 adult male, 572 mm TL, 71° 7.45′S,
176° 23.743′E, 12 Mar 2002, 1280–1300 m depth; NMNZ
P.038602, 1 adult male, 572 mm TL, 72° 18.00′S, 179°
16.500′W, 25 Feb 2002, 832–1067 m depth; NMNZ
P.038603, 1 adult female, 510 mm TL, 72° 18.00′S, 179°
16.500′W, 25 Feb 2002, 832–1067 m depth; NMNZ
P.038617, 1 male, 494 mm TL, 1 adult female 584 mm TL,
71° 17.70′S, 178° 23.700′W, 06 Mar 2002, 991–1052 m
depth; NMNZ P.038618, 2 adult females, 510 and 562 mm
TL, 1 adult male, 544 mm TL, 72° 32.40′S, 179° 20.100′W,
23 Feb 2002, 831–912 m depth; NMNZ P.038626, 1 adult
female, 557 mm TL, 71° 47.70′S, 177° 25.800′W, 26
Jan 2002, 757–784 m depth; NMNZ P.038649*, 1 adult fe-
male, 590 mm TL, 71° 24.60′S, 177° 28.200′W, 20 Jan 2002,
890–999 m depth; NMNZ P.038653, 1 adult female, 530 mm
TL, 75° 47.10′S, 169° 10.800′W, 09 Feb 2002, 894–1117 m
depth; NMNZ P.038657, 1 adult female, 585 mm TL, 71°
24.60′S, 177° 28.200′W, 20 Jan 2002, 890–999 m depth;
NMNZ P.038781, 1 adult female, 577 mm TL, 71° 14.58′S,
176° 28.608′E, 03 Mar 2002, 1118–1295 m depth; NMNZ
P.038818, 1 adult female, 592 mm TL, 71° 22.498′S, 176°
47.9993′E, 30 Jan 2003, 1385–1450 m depth; NMNZ
P.038824, 1 adult male, 530 mm TL, 61° 15.00′S, 55°
20.00′W, 16 Mar 2003; NMNZ P.038831*, 1 adult female,
543 mm TL, 61° 15.00′S, 55° 20.00′W, 17 Mar 2003;
NMNZ P.038834*, 1 adult male, 523 mm TL, 61° 15.00′S,
55° 20.00′W, 16 Mar 2003; NMNZ P.038835*, 1 adult fe-
male, 495 mm TL, 61° 15.00′S, 55° 20.00′W, 16 Mar 2003;
NMNZ P.040066, 1 adult male, 593 mm TL, 71° 44.2550′S,
Table 3 Bathyraja arctowskii, morphometrics of pelvic girdle based on radiographs, plus interorbital width dorsally and shoulder girdle maximum
width as reference values. Proportional values are expressed as percentages of pelvic girdle maximum width (PGW)
Primary adult
male, ZMH
120216, 533 mm
TL
Primary adult female with
extreme tail tip missing, ZMH
123230, 535 mm TL
Primary subadult
male, ZMH
121822, 424 mm
TL
Primary subadult
female, ZMH
114702, 427 mm
TL
mm %PGW mm %PGW mm %PGW mm %PGW
Interorbital width dorsally 19.0 36.1 16.0 27.8 13.0 34.6 13.0 33.8
Shoulder girdle max. width 76.1 144.7 Damaged Damaged 58.2 154.6 69.8 181.4
Pelvic girdle max. width (PGW) 52.6 100.0 57.6 100.0 37.6 100.0 38.5 100.0
Median transverse thickness 6.6 12.5 7.8 13.5 4.4 11.6 5.0 13.0
Length prepelvic process (from level PGW) 21.1 40.2 25.8 44.8 19.1 50.7 18.1 47.0
Length prepelvic proc. (from level ant. edge pelvic girdle) 16.4 31.2 18.7 32.4 14.1 37.6 10.7 27.8
Depth posterior arc (from level PGW) 11.1 21.0 9.3 16.1 6.9 18.4 4.7 12.2
Depth post. arc (from level post. edge pelvic girdle) 8.9 16.9 8.6 15.0 7.3 19.4 6.8 17.7
Iliac foramina number 2 2 2 2
Marine Biodiversity (2021) 51:18 Page 7 of 27 18

171° 39.7650′E, 05 Feb 2004, 400–415 m depth; NMNZ
P.040340, 1 adult female, 533 mm TL, 1 adult male,
565 mm TL, 71° 42.3450′S, 172° 1.9000′E, 05 Feb 2004,
621–636 m depth; NMNZ P.040570, 1 female, 462 mm TL,
72° 45.67′S, 174° 21.900′E, 15 Jan 2004, 398–420 m depth;
NMNZ P.040900, 1 adult female, 555 mm TL, 71° 30.50′S,
178° 0.60′W, 19 Feb 2004, 1048 m depth; NMNZ P.041370,
1 adult female, 525 mm TL, 73° 12.20′S, 177° 24.602′W, 28
Dec 2004, 705–789 m depth; NMNZ P.041374, 1 adult fe-
male, 540 mm TL, 72° 8.60′S, 178° 19.800′W, 12 Jan 2005,
789–900 m depth; NMNZ P.041380, 1 female and 1 male
specimen, one has 550 mm TL, 75° 15.00′S, 174° 7.200′
W, 07 Jan 2005, 1206–1270 m depth; NMNZ P.041381, 2
adult males, 545 and 550 mm TL, 72° 15.20′S, 178° 55.200′
W, 19 Jan 2005, 781–832 m depth; NMNZ P.041382, 1 adult
female, 575 mm TL, 72° 14.20′S, 178° 43.000′W, 12
Jan 2005, 774–842 m depth; NMNZ P.041383, 2 adult fe-
males, 515 and 560 mm TL, 75° 24.30′S, 172° 29.550′W,
09 Jan 2005, 1156–1224 m depth; NMNZ P.041384, 1 fe-
male, 440 mm TL, 75° 11.40′S, 175° 3.150′W, 31
Jan 2005, 1091–1166 m depth; NMNZ P.041385, 1 adult
male, 565 mm TL, 72° 15.20′S, 179° 7.802′W, 19
Jan 2005, 831–996 m depth; NMNZ P.041392, 1 adult male,
530 mm TL, 75° 33′S, 170° 1.80′W, 04 Feb 2005, 985–1065
m depth; NMNZ P.041394, 1 adult male, 490 mm TL, 75° 10′
S, 175° 6.00′W, 07 Feb 2005, 1013–1242 m depth; NMNZ
P.041395, 1 juvenile specimen, 225 mm TL, 75° 33.40′S,
170° 4.600′W, 05 Feb 2005, 965–1072 m depth; NMNZ
P.041418, 1 adult male, 580 mm TL, 75° 0.00′S, 174° 0.00′
W, 07 Feb 2005, 984 m depth; NMNZ P.041445, 1 adult
female, 555 mm TL, 66° 29.80′S, 78° 19.200′E, 09 Mar
2005, 790–972 m depth; NMNZ P.042224, 1 adult male,
565 mm TL, 72° 0.30′S, 178° 24.900′W, 11 Jan 2006,
867–954 m depth; NMNZ P.042225, 1 adult male, 600 mm
TL, 71° 34.80′S, 178° 26.10′W, 11 Jan 2006, 869–1001 m
depth; NMNZ P.042226, 1 specimen, 540 mm TL, 72° 2.70′
S, 178° 46.500′W, 12 Jan 2006, 1041–1160 m depth; NMNZ
P.042244, 1 female, 470 mm TL, 71° 21.90′S, 116° 32.100′
W, 07 Feb 2006; NMNZ P.042721, 1 adult male, 595 mm TL,
72° 3.15′S, 174° 14.850′E, 23 Jan 2007, 1189–1522 m depth;
Table 4 Bathyraja arctowskii, morphometrics of left scapulocoracoid based on dissected elements. Proportional values are expressed as percentages of
the element’s maximum length
Adult female, ZMH 115243,
330 mm disc width
Adult male, ZMH 115243,
300 mm disc width
mm % max.
length
mm % max.
length
Maximum length 40.9 100.0 34.7 100.0
Maximum height 25.3 61.9 27.0 77.8
Height at rear corner 21.6 52.8 22.5 64.8
Pre-mesocondyle-length 10.5 25.6 13.2 38.0
Post-mesocondyle-length 29.4 71.9 22.5 64.8
Anterior dorsal fenestra height 4.2 10.2 4.7 13.5
Anterior dorsal fenestra length 4.5 11.0 4.0 11.5
Anterior ventral fenestra height 5.9 14.3 4.8 13.8
Anterior ventral fenestra length 4.6 11.3 3.5 10.1
Height ant. dorsal + ant. bridge + ant. ventral fenestra
combined
11.0 26.8 10.1 29.1
Height largest postdorsal fenestra 5.6 (1st) 13.6 5.7 (1st) 15.2
Length largest postdorsal fenestra 7.8 (1st) 19.1 5.8 (1st) 16.7
Height 2nd largest postdorsal fenestra 2.1 5.1 6.2 17.9
Length 2nd largest postdorsal fenestra 2.4 14.4 5.0 14.4
Height smallest postdorsal fenestra 1.0 2.5 ––
Length smallest postdorsal fenestra 0.9 2.2 ––
Height largest postventral fenestra 3.4 (1st) 8.3 3.0 8.6
Length largest postventral fenestra 6.3 (1st) 15.3 2.9 8.4
Height smallest postventral fenestra 1.3 3.2 1.0 2.9
Length smallest postventral fenestra 1.9 4.5 1.0 2.9
Total number postdorsal fenestrae 5–62
Total number postventral fenestrae 4 5
18 Page 8 of 27 Marine Biodiversity (2021) 51:18

NMNZ P.043593, 1 specimen, 73° 15.3000′S, 178° 44.2650′
E, 19 Feb 2008, 760–770 m depth; NMNZ P.043642, 1 im-
mature male, 72° 19.1050′S, 175° 29.5050′E, 21 Feb 2008,
980 m depth; NMNZ P.046622, 1 juvenile female, 271 mm
TL, 71° 4.450′S, 179° 52.200′E, 31 Dec 2009, 1179–1342 m
depth; NMNZ P.046624, 1 juvenile specimen, 165 mm TL,
71° 1.900′S, 179° 38.15′E, 01 Jan 2010, 1066–1334 m depth;
NMNZ P.051853, 1 adult specimen, 606 mm TL, 65° 15.12′
S, 175° 32.52′W, 03 Jan 2011, 1652–1685 m depth; NMNZ
P.051854, 1 adult specimen, 572 mm TL, 72° 7.58′S, 176°
18.60′W, 29 Dec 2010, 825–855 m depth; NMNZ P.051855,
1 adult specimen, 586 mm TL, 72° 7.58′S, 176° 18.60′W, 29
Dec 2010, 825–855 m depth.
Egg capsules (n=43):Syntypes: IRSNB 25 [orig. 3005],
71° 19′S, 87° 37′W, 27–28 May 1898, 435 m depth; IRSNB
26 [orig. 3006], 70° 23′S, 82° 47′W, 7–8 Oct 1898, 400 m
depth; IRSNB 27 [orig. 3007], 70° 15′S, 84° 06′W, 19–20
Dec 1898, 569 m depth; ZMH 9014, 1 empty egg capsule and
1 egg capsule with 1 near-term male embryo, 120 mm TL, 61°
13.9′S, 56° 25.4′W, 21.11.96, 403–415 m depth; ZMH 9015,
7 egg capsules with early embryos, 60° 57.6′S, 55° 11.8′W,
25.11.96, 326–380 m depth; ZMH 9016, 1 egg capsule with
early embryo, 61° 00.6′S, 55° 07′W, 25.11.96, 145–156 m
depth; ZMH 9017, 4 egg capsules with early embryos, 61°
43.3′S, 59° 12.5′W, 27.11.96, 573–590 m depth; ZMH
123265 (ex ISH 203-1987), 5 egg capsules, 61° 13.12′S,
56° 06.42′W, 16.12.87, 230–250 m depth; ZMH 123275
(ex ISH 199-1987), 1 egg capsule, 60° 52′S, 55° 31.48′W,
14.12.87, 264–267 m depth; ZMH 123276 (ex ISH 202-
1987), 19 egg capsules, 61° 20.18′S, 56° 08.24′W,
16.12.87, 295–311 m depth; ZMH 123277 (ex ISH 204-
1987), 1 egg capsule, 61° 09.18′S, 56° 11.06′W, 16.12.87,
387–426 m depth.
Diagnosis
Bathyraja arctowskii is a small (to 61 cm TL) species of the
genus Bathyraja with the following set of characters: disc
evenly inverse heart-shaped (disc margins distinctly undulated
in adult males, not or slightly undulated in others), with broad-
ly rounded outer corners and with body length to mid-cloaca
shorter than or equal to tail length from mid-cloaca. Preorbital
snout length 8.1–16.2% TL, depending on ontogenetic stage,
and distance between first gill slits 14.2–15.9% TL. Orbits
moderately large, horizontal diameter 1.3–1.8 times interor-
bital width. Upper side of disc and tail entirely rough prickly
with dermal denticles, underside smooth. Except for alar
thorns of mature males, no thorns on disc but only a median
row of 19–30 small thorns along tail to first dorsal fin. The
thorns become smaller and more widely spaced posteriorly in
subadults and adults and are generally wider spaced in large
juveniles to adults as compared with small juveniles. Bases of
Table 5 Bathyraja arctowskii, morphometrics of two egg capsules cataloged under ZMH 9014, all values given in millimeters
empty egg capsule egg capsule
with embryo
ECTL_1, egg case total length incl. length of bent horns (along curve)
1
141.5 146.4
ECTL_2, egg case total length incl. horizontal length of bent horns
2
121.8 120.2
ECL, egg case length; measured longitudinally between the anterior and posterior apron borders
3
77.6 76.1
AAL, anterior apron length
4
5.1 5.1
PAL, posterior apron length
4
12.6 12.9
ABW, anterior border width; distance between the bases of the anterior horns
3
20.1 20.0
PBW, posterior border width; distance between the bases of the posterior horns
3
21.0 21.1
MAW, maximum case width; transverse width of the case in its lateral plane at its widest part of the case
3
42.3 40.7
MIW, minimum case width; transverse width of the case in its lateral plane at its narrowest part of the case
3
34.5 34.4
LKW, lateral keel width; distance from the capsule keel junction to the keel edge
3
1.5 0.6
CBL, central body length (excl. aprons)
1
61.5 58.4
CBW, central body width (excl. lateral keels)
1
39.1 39.9
CH, Capsule height (maximum height)
5
18.9 18.9
AHL_1, anterior horn length; distance from the horn base to the tips (along curve)
3
34.0 39.0
PHL_1, posterior horn length; distance from the posterior horn base to the tips (along curve)
3
46.0 49.0
AHL_2, anterior horn length; horizontal length between perpendicular lines
1
24.9 25.0
PHL_2, posterior horn length; horizontal length between perpendicular lines
1
37.5 34.5
1
Newly introduced measurement,
2
measured after Treloar et al. (2006),
3
measured after Ebert and Davis (2007),
4
measured after Concha et al. (2009),
5
measured after Concha et al. (2012)
Marine Biodiversity (2021) 51:18 Page 9 of 27 18

low, more or less equal-sized dorsal fins confluent or with
short interspace. Postdorsal tail section very short, 1.7–5.2%
TL, with low epichordal caudal lobe which is confluent with
second dorsal fin. Dorsal ground color plain dark to medium
grayish-brown, often with mostly indistinct scattered pale and
dusky spots on disc, posterior pelvic lobes and on sides of tail,
occasionally with transverse white pseudoocellus stripe on
inner posterior pectorals. Underside mostly plain white or
pale, often with gray marked cloaca and gray spots on belly
to gill region, occasionally gray spotted posterior pectoral
margins, origin and sides of tail, or tail partly dark. Mouth
cavity and underside of nasal curtain at least partly, usually
completely pigmented medium to dark grayish from very
small juvenile stages onwards. Opened clasper tip shows all
components typical for Bathyraja species, of which most ap-
parent a long and deep pseudosiphon (ps) along outer edge of
Table 6 Tissue samples used for molecular analyses
Species Identifier TePapa catalog no. Locality
Bathyraja arctowskii GN 17896 P.038649/TS2 -71.41, 177.47
Bathyraja arctowskii GN 17897 P.038831/TS3 -61.25, -55.33
Bathyraja arctowskii GN 17898 P.038834/TS3 -61.25, -55.33
Bathyraja arctowskii GN 17899 P.038835/TS3 -61.25, -55.33
Bathyraja cf. eatonii GN 15726 -66.85, 64.93
Bathyraja cf. eatonii GN 17861 P.038826/TS3 Off South Shetland Islands
Bathyraja cf. eatonii GN 17862 P.038827/TS3 Off South Shetland Islands
Bathyraja cf. eatonii GN 17864 P.038829/TS2 Off South Shetland Islands
Bathyraja cf. eatonii GN 17855 P.038825/TS2 Off South Shetland Islands
Bathyraja cf. eatonii GN 17856 P.040069/TS2 -71.50, 171.79
Bathyraja cf. eatonii GN 17857 P.040095/TS2 -71.72, 171.8
Bathyraja cf. eatonii GN 17859 P.040345/TS2 -72.03, 173.25
Bathyraja eatonii GN 15722 -52.25, 76.68
Bathyraja eatonii GN 15724 -52.25, 76.68
Bathyraja eatonii GN 15727 -51.98, 77.43
Bathyraja irrasa GN 15711 -51.95, 76.90
Bathyraja maccaini GN 15715 -66.63, 72.90
Bathyraja maccaini GN 15716 -66.63, 72.90
Bathyraja maccaini GN 15717 -66.72, 73.00
Bathyraja maccaini GN 15719 -66.63, 72.90
Bathyraja maccaini GN 15720 -66.70, 61.42
Bathyraja maccaini GN 17865 P.036191/TS2 -75.72, 168.80
Bathyraja maccaini GN 17866 P.036196/TS2 -75.72, 168.80
Bathyraja maccaini GN 17867 P.038832/TS3 -61.25, -55.33
Bathyraja maccaini GN 17868 P.038833/TS2 -61.25, -55.33
Bathyraja maccaini GN 17869 P.038836/TS3 -61.25, -55.33
Bathyraja maccaini GN 17870 P.040064/TS2 -71.72, 171.80
Bathyraja maccaini GN 17871 P.040065/TS2 -71.70, 172.09
Bathyraja maccaini GN 17872 P.040335/TS2 -72.070, 172.92
Bathyraja maccaini GN 17874 P.040897/TS3 -77.33, -160.42
Bathyraja maccaini GN 17875 P.040898/TS4 -77.33, -160.42
Bathyraja meridionalis GN 17876 P.042494/TS3 -53.23, -42.37
Bathyraja meridionalis GN 17877 P.042495/TS3 -55.44, -36.26
Bathyraja meridionalis GN 17880 P.042505/TS3 -55.16, -36.37
Bathyraja meridionalis GN 17881 P.042507/TS3 -55.17, -36.37
Bathyraja murrayi GN 15714 -52.55, 75.06
Bathyraja sp. GN 17854 P.043485/TS2 -76.77, 167.83
18 Page 10 of 27 Marine Biodiversity (2021) 51:18

dorsal lobe, as well as a massive projection (pj) over
entire length of the inner ventral lobe. Clasper terminal
skeleton with distal processes of dorsal marginal carti-
lage (forming external pseudorhipidion) and ventral
marginal cartilage (forming external projection), three
dorsal terminal cartilages (with dt1 very large and en-
capsulating terminal skeleton), ventral terminal, and one
accessory terminal cartilage. Sexual dimorphism appar-
ent in scapulocoracoid, with post-mesocondyle length
longer in females than in males.
Description The description refers to the primary adult male
ZMH 120216 (ex ISH 489-1981). Values of 10 other primary
specimens examined in detail are presented in parentheses,
more complex differences between specimens are described
separately. Where relevant, ratios are based on horizontal
measurements unless otherwise stated. Detailed morphomet-
ric measurements and meristics are given in Table 1.
External morphology (Figs. 1,2,3,4,5,6,7,8,9,10,11,
12,13,14,15, and 16). Disc evenly inverse heart-shaped,
anterior margins undulated showing concavity at anterior
sides of snout and at level of nape (disc margins not undulated
in small juveniles and adult females, slightly undulated in
large juveniles and subadults), outer corners of disc broadly
rounded. Disc width 1.2 (1.2–1.4) times disc length, markedly
wide. Axis of maximum disc width at 30.0% (24.2–31.9%)
TL, or 54.1% (54.7–61.0%) of disc length, and distinctly pos-
terior to shoulder girdle. Dorsal head length 19.9% (14.2–
21.6%) TL. Snout tip somewhat pronounced, narrowly round-
ed; snout moderately elongated and pointed at 110° angle
(112–120° in subadults and adult female, 125–133° in juve-
niles, 140° in male embryo), with preorbital length 13.6%
(11.4–16.2% in subadults and adult female, 9.6–11.6% in ju-
veniles, 8.1% in male embryo) TL and 3.8 (3.7–5.3insub-
adults and adult female, 2.5–3.6 in juveniles, 2.2 in male em-
bryo) times the narrow interorbital width. Orbit horizontal
Table 7 Possible ontogenetic changes of Bathyraja arctowskii based on values for subadult plus adult specimens, juveniles, and a male embryo
Character Subadults and adults
(n=4,424–535 mm TL)
Juveniles
(n=6,135–333 mm TL)
Male embryo
(n= 1, 120 mm TL)
Snout angle 110–120° 125–133° 140°
Preorbital snout length 11.4–16.2% TL 9.6–11.6%TL 8.1%TL
Preorbital snout length/internarial width 3.7–5.3 times 2.5–3.6 times 2.2 times
Preoral snout length 11.1–15.2% TL 9.0–11.3%TL 8.8%TL
Prenasal snout length 9.1–12.9% TL 7.4–9.4% TL 7.4% TL
Orbit, horizontal diameter 4.1–4.8% TL 4.6–5.8% TL 5.4% TL
Eyeball, horizontal diameter 3.4–3.7% TL 3.9–4.6% TL 4.4% TL
Interspiracular width 7.0–7.9% TL 7.9–8.8% TL 8.7% TL
Tail height at pelvic tips 2.0–2.2% TL 2.3–3.0% TL 4.3% TL
Tail width/height at pelvic tips 1.5–1.8 times 1.1–1.5 times 1.1 times
Tail height at 1st dorsal-fin origin 0.7–0.9% TL 0.9–1.3% TL 1.3% TL
Tail width/height at 1st dorsal-fin origin 1.7–2.6 times 1.1–1.8 times 1.4 times
Lateral tail fold length 44.3–47.7% TL 35.0–47.6% TL 32.8% TL
Ventral head length 25.0–28.0% TL 21.5–25.9% TL –
Dorsal head length 17.6–21.6% TL 16.8–18.7% TL 14.2% TL
Nasal curtain length 3.4–4.1% TL 2.8–3.4% TL 2.4% TL
Space between lobes of nasal curtain 4.0–5.3% TL 2.8–4.0% TL 3.3% TL
Snout tip to mid-cloaca 45.6–49.6% TL 41.9–45.6% TL 41.3% TL
Snout tip to 1st hemal spine 48.0–51.5% TL 43.8–48.2% TL –
Mid-cloaca to 1st dorsal-fin origin 38.4–42.8% TL 44.1–46.4% TL 46.7% TL
Mid-cloaca to 2nd dorsal-fin origin 42.5–47.4% TL 48.2–50.4% TL 52.3% TL
Mid-cloaca to tail tip 49.4–52.7% TL 53.2–59.3% TL 60.2% TL
Mid-cloaca to tail tip/snout tip to mid-cloaca 1.0–1.2 times 1.2–1.4 times 1.5 times
Dorsal color pattern of light dots and streaks Usually faded Distinct to mostly faded in large juveniles Distinct even in
preserved condition
Marine Biodiversity (2021) 51:18 Page 11 of 27 18

diameter 1.3 (1.3–1.8) times interorbital width and 1.5 (1.5–
2.0) times length of spiracle depression; interspiracular space
wide, 2.2 (2.2–2.6) times interorbital space; about 10
pseudobranchial folds in each spiracle. Tail slender, gradually
tapering towards tip; a low triangle in cross-section, width at
level of pelvic tips 1.5 (1.6–1.8 in adult female and subadults,
1.1–1.5 in juveniles, 1.1 in male embryo) times height, width
at first dorsal-fin origin 2.6 (2.5 in adult female, 1.7–2.2 in
subadults, 1.1–1.8 in male embryo and juveniles) times
height; tail length from mid-cloaca 1.0 (1.0–1.2 in adult fe-
male and subadults, 1.2–1.4 in juveniles, 1.5 in male embryo)
times distance snout tip to mid-cloaca. Both dorsal fins
parallelogram-shaped with broadly rounded upper margin
and somewhat frayed tip widely overhanging base end; pos-
terior margin strongly inclined forward and concave; both
dorsal fins about as long as high (first dorsal-fin base length
1.0–2.8 times height and second dorsalfin base length 1.3–2.6
times height in other specimens), base of first dorsal fin 1.6
(0.6–1.2) times that of second dorsal fin. Bases of both dorsal
fins confluent without interspace (confluent or with very small
interspace). Postdorsal tail short, 65.2% (47.4–155.6%) of
second dorsal-fin base length, with a low and indistinct
epichordal caudal fold confluent with second dorsal fin, height
of epichordal lobe ~14% (0–~30%)ofseconddorsal-fin
height; hypochordal caudal fold absent. Lateral tail folds
along full tail length (along full length also in adult female
and subadults but along about posterior two thirds to almost
full length in juveniles and male embryo).
Ventral head length 28.0% (25.0–27.9% in adult female
and subadults, 21.5–25.9% in juveniles, not measurable in
male embryo) TL. Preoral snout length 1.9 (1.5–2.3) times
internarial width and 1.6 (1.2–2.4) times mouth width, the
latter 27.4% (22.9–36.7%) of ventral head length and
115.5% (97.5–129.4%) of internarial space; ventral head
length 4.2 (3.2–4.3) times internarial space; distance between
5th gill slits 63.0% (58.5–81.9%) of distance between 1st gill
Fig. 1 Bathyraja arctowskii, ZMH 120216, primary adult male, 533 mm
TL, in total dorsal view. Scale bar: 5 cm
Fig. 2 Bathyraja arctowskii, ZMH 120216, primary adult male, 533 mm
TL, in total ventral view. Scale bar: 5 cm
Fig. 4 Bathyraja arctowskii, ZMH 123230, primary adult female,
535 mm TL, in total ventral view. Scale bar: 5 cm
Fig. 3 Bathyraja arctowskii, ZMH 123230, primary adult female,
535 mm TL, in total dorsal view. Scale bar: 5 cm
18 Page 12 of 27 Marine Biodiversity (2021) 51:18

slits, the latter 2.2 (2.1–2.4) times internarial space. Anterior
nasal flaps rather small and smooth-edged. Outer edges of
nasal curtain smooth and not notched, apices rounded, their
outer margin smooth; rear margin of curtain weakly fringed by
broad and fleshy fringes; isthmus deeply arc-shaped. Jaws
weakly angled, with 23 upper and 24 lower parallel tooth rows
(22–29 upper and 21–29 lower tooth rows; arrangement sim-
ilar in subadult male but teeth in quincunx pavement pattern in
females, juvenile males and male embryo); individual teeth
with pronounced, triangular cusp becoming smaller towards
jaw angles (similar in subadult male but with rather low cusp
in females, juvenile males and male embryo). Anterior and
posterior pelvic-fin lobes separated by a deep notch, posterior
lobe with angular outer margin and rounded tip 1.6 (1.1–1.5)
times longer than solid anterior lobe tapering to a blunt tip.
Fully developed claspers long and slender, with terminal re-
gion only somewhat widened; distal half of clasper stem plus
terminal region exceeding tips of posterior pelvic lobes; clasp-
er postcloaca length 50.6% of tail length from mid-cloaca.
Squamation (Figs. 1,2,3,4,5,6,12,13, and 14). No
thorns on upper disc except for very elongated field of alar
thorns across outer pectoral corners and parallel to anterior
half of posterior margins; alar thorns hook-like and of non-
retractable, permanently erect type; alar thorns set in three to
five longitudinal and ~20 transverse rows (Fig. 12). Tail with
~26 median thorns from between pelvic and pectoral inser-
tions to somewhat anterior to first dorsal-fin base; thorns be-
come smaller and more widely spaced posteriorly (Figs. 13
and 14). Other specimens with about 19 to 30 median tail
thorns, which become smaller and more widely spaced poste-
riorly in subadults and adults and are generally wider-spaced
in large juveniles to adults as compared with small juveniles.
No interdorsal thorns (none also in other specimens except for
one tiny thorn in smallest juvenile female).
Dorsal surface almost completely and densely set with fine
dermal denticles, including the integument covering the eye-
balls, as well as caudal and dorsal fins, but somewhat more
loosely set on pectoral centers and axils; posterior pelvic-fin
lobes smooth. The spinulation is similar in adult female and
subadult male except for the presence of a few denticles on
centers of posterior pelvic-fin lobes. The subadult female is
almost completely covered with fine dermal denticles as well,
but with largely smooth pectoral centers, as well as smooth
integument covering the eyeballs and posterior pelvic-fin
lobes. Dorsal surface of juveniles completely and densely
covered with fine dermal denticles except for a more loose
Fig. 6 Bathyraja arctowskii,
ZMH 9014, near-term male em-
bryo, 120 mm TL, in total ventral
view. Scale bar: 2 cm
Fig. 5 Bathyraja arctowskii,
ZMH 9014, near-term male em-
bryo, 120 mm TL, in total dorsal
view. Scale bar: 2 cm
Marine Biodiversity (2021) 51:18 Page 13 of 27 18

coverage of rostral sides in two specimens. Ventral surface
completely smooth in adult male and all other specimens.
Coloration: when fresh (Figs. 15 and 16): medium to dark
brown dorsally, disc and pelvic fins with pattern of light dots
and streaks (more pronounced in juveniles). Occasionally,
dorsally lively ornamented specimens are found (Fig. 15).
Underside of disc and tail whitish; pale dark spots may be
present on tail and centrally on disc. Mouth cavity and under-
side of nasal curtain at least partly, usually completely
pigmented medium to dark grayish.
Color in preservative (Figs. 1,2,3,4,5,6): pattern of light
dots and streaks faded, particularly in adult specimens, some
of which appear plain medium to dark brown. Ventral color-
ation rather beige than whitish, with dark spots still visible.
Dark pigmentation of mouth cavity and underside of nasal
curtain still conspicuous.
Clasper external morphology (Fig. 17, based on one badly
disintegrated male from ZMH 115243 [ex ISH 689-1978]).
Clasper stem a solid rod of equal width, with the glans only
little widening and short. The apparent component of the
dorsal lobe is a deep and long pseudosiphon (ps) along the
outer margin extending over three fourths of the glans length.
A cleft (cf) is found in distal half of the glans between the axial
cartilage ridge and the inner wall of dorsal lobe. A narrow
cartilage rod is situated medially in proximal glans, the
pseudorhipidion (pr), which covers proximally the axial carti-
lage (ax). The latter continues visible on deeper level as a ridge
from underneath tip of pr to the extreme tip of the glans. Very
prominent component on entire length of ventral lobe is the
somewhat twisted and long projection (pj), a firm cartilage
covered by integument and connected to outer ventral lobe
margin with integument. A deep and wide sentina hollow
(sn, indicated hatched) underneath the pj and the integument
spanning to outer ventral lobe margin runs out with its prox-
imal wall as a narrow integument ridge diagonally across the
axial cartilage to the proximal end of the cleft. Within the
sentina, externally not visible, is the ax-blade-like tip of the
sentinel (st) found as a sharp cutting tip edge of the at1
cartilage.
Fig. 7 Bathyraja arctowskii, ZMH 120216, primary adult male, 533 mm
TL, head in dorsal view. Scale bar: 5 cm
Fig. 8 Bathyraja arctowskii, ZMH 120216, primary adult male, 533 mm
TL, head in ventral view. Scale bar: 5 cm
Fig. 9 Bathyraja arctowskii, ZMH 120216, primary adult male, 533 mm
TL, close-up of orbital and spiracular region. Scale bar: 2 cm
Fig. 10 Bathyraja arctowskii, ZMH 120216, primary adult male,
533 mm TL, close-up of mouth-nasal region. Scale bar: 2 cm
18 Page 14 of 27 Marine Biodiversity (2021) 51:18

Both outer surfaces of the clasper, as well as inner surfaces
of the open glans are smooth without a trace of dermal
denticles.
Clasper skeleton (Fig. 18, based on one primary and one
additional male, both badly disintegrated, from ZMH
115243). Figure 18a+bshows the distal part of the clasper
stem in dorsal and ventral views, with the axial (ax), dorsal
marginal (dm), and ventral marginal (vm) cartilages and car-
tilages of the glans. Prominent cartilage in dorsal view is the
dorsal terminal 1 (dt1) encapsulating nearly the entire terminal
surface dorsally, showing longitudinal ridges and grooves and
curving onto the ventral side around the axial. Very distally
appears a blunt, short tip of the dm-cartilage, as well as a
narrow, elongated distal process, the dorsal terminal 3 (dt3).
The thin tip of the ax-cartilage the same length as the former
one but curving outward to connect with the tip of the slender
dt3-process. Tip of the vm-process (= pj externally) solid and
curving a little downwards.
Ventral view of Fig. 18b shows the ventral part of the dt1
around the axial as well as the outer dorsal part of dt1
supporting the outer edge of external component
pseudosiphon. The ventral terminal (vt) cartilage is an elon-
gated drop-shaped plate, narrowing proximally, and posi-
tioned medially over the axial and ventral marginal (vm),
but is not movable and does not appear as an external compo-
nent in the glans. Prominent cartilage is the massive distal
process of the vm = external component pj. The blunt distal
end of the dm appears underneath the vm-process, as well as
both slender distal tips of ax and dt3.
Figure 18c+dshows the terminal clasper skeleton in dorsal
and ventral views, with dt1 and vt removed. The dorsal mar-
ginal cartilage (dm) occupies almost the entire dorsal surface,
including the axial, from the stem to the distal tip and is dif-
ficult to interpret with its structures and distal tips. Tip of the
vm-process sticking out at inner distal edge, and edge of the
vm visible in proximal half. The ventral view (d) shows the
vm-cartilage curving and widening distally, with its massive
and long process (= external pj) inserting proximally under-
neath the outer edge of the vm, and the at1-cartilage inserting
under inner distal edge. The slender, outward curving tip of
the axial appears underneath the at1-level.
Figure 18e, with dt1 included, and f, without dt1, show the
spread terminal skeleton. Most distally are visible the tips of
the vm-process and the slender axial end connected to the
slender dt3-process, also medially the dm-process (= external
pr) and at outer left the tip of the at1-cartilage. Figure 18f
shows the same arrangement of terminal cartilages without
the capsule-shaped dt1 in the background.
Remark: this clasper skeleton is not yet fully calcified, or
decalcified by preservation, partly still soft and flexible, but
displays all external glans components and its skeleton carti-
lages. Exception is the slender distal outer edge process of the
dm, which is connected with the extreme tip of the axial. A
majority of Bathyraja species possesses in this position a dor-
sal terminal 2 (dt2) or dt3 cartilage, likewise connected with
ax-tip. Such a separate dt3-cartilage is indicated in Fig. 18c
along the outer dm-margin but may not yet be fully formed
and calcified.
Therefore, the left clasper of another adult male (also from
ZMH 115243),which was badly disintegrated as well but with
claspers more hardened and more calcified skeleton, was dis-
sected and skeletal elements were found identical with those
of the male illustrated here. Contour of the questionable and
better-calcified dt2 was more distinct and could be cut and
lifted at the outer margin, and could thus be proven as a sep-
arate dt2 cartilage. However, the dt2 is plate-like and firmly
attached with its entire lower surface to the dm surface. The
dt2 has no joint connecting it with the dm and is static and not
movable. Questionable remains, whether the long, thin and
Fig. 11 Bathyraja arctowskii, ZMH 120216, primary adult male,
533 mm TL, pelvic region with tail origin and pair of claspers in dorsal
view. Scale bar: 5 cm
Fig. 12 Bathyraja arctowskii, ZMH 120216, primary adult male,
533 mm TL, left field of alar thorns. Scale bar: 2 cm
Marine Biodiversity (2021) 51:18 Page 15 of 27 18

hardly calcified distal extension of the dt2, connecting with a
narrow tissue bridge to the distal end of the axial cartilage, is
distal part of the dt2, or a separate dt3 cartilage. The delicate
terminal cartilages of the very small, only 2 to 2.5 cm long
glans do presently not allow a definitive decision on 2 or 3 dt-
cartilages, but we tend here to 3 dt-cartilages. Bathyraja spe-
cies with both, 2 and 3 dt-cartilages are known.
Cranium (Figs. 19 and 20). Table 2provides cranial mor-
phometrics taken from the four largest primary specimens at
ZMH.
Although the crania did not depict very well on radio-
graphs, as is typical for deep-waterBathyraja spp. due to their
low calcification of cartilage, most cranial morphometrics
could be measured with acceptable accuracy. The short ante-
rior cranial fontanelle is broadly bullet- or spearhead-shaped;
front part bluntly pointed, the fontanelle then gradually
widens rearwards to widest part at about four fifths of fonta-
nelle length but narrows again in posterior-most fifth of the
fontanelle. The posterior cranial fontanelle is not or hardly
visible on radiographs but appears to be an elongated, narrow
triangle with tip pointing rearwards as vaguely visible in the
radiograph of the cranium of the adult female (Fig. 20). As
typical in Bathyraja crania, the rostrum narrows abruptly in
front of the anterior fontanelle, and the uncalcified anterior
two thirds of the very slender, undulated rostral cartilage are
not depicted.
Ovoid nasal capsules large and strongly forwardly inclined
at a 54–75° angle of their straight rear edges to longitudinal
axis of cranium. Orbital region evenly deeply concave; otic
region broadly bulky, with short occipital condyles and small
jugal arches not or hardly exceeding the contour of the occiput
rearward or laterally. Snout supported by forward extension of
pectoral propterygia and radials extended to nearly snout tip
and rostral node. Rostral shaft length 44.5–53.8% of cranium
total and 80.9–116.5% of nasobasal length; maximum ethmoi-
dal width 45.1–56.9% of cranium total length, 95.8–103.7%
of nasobasal length, 2.9–3.4 times minimum dorsal interorbit-
al width, and 1.7–1.9 times maximum width of otic region.
Anterior fontanelle length 18.7–38.9% of rostral shaft and
10.1–17.9% of cranium total length, its length 0.9–1.8 times
its maximum width, and its tip hardly extending into rostral
shaft length.
Pelvic girdle (Figs. 21 and 22). Table 3provides pelvic
morphometrics taken from the four largest primary specimens
at ZMH.
The maximum width of shoulder girdle, which shows a
rather slender coracoid bar, and the maximum width of the
pelvic girdle apparently show sexual dimorphism, with dimor-
phism of shoulder girdle maximum width evidenced by ratio
shoulder girdle maximum width / dorsal interorbital width
(4.0 and 4.5 times in males, 5.4 times in adolescent female)
and dimorphism of pelvic girdle shown by ratio maximum
width of shoulder girdle / maximum width of pelvic girdle
(1.4 and 1.5 in males, 1.8 in adolescent female). However,
this assumption is based on only three specimens and the
differences might also be the result of intraspecific variation.
The ratios could not be taken for the adult female due to the
shoulder girdle being severely damaged.
Pelvic girdle with massive ischiopubic bar, anterior contour
nearly straight in both sexes at all sizes, posterior contour
slightly concave in females and juvenile males but deeply so
in adult males; prepelvic processes moderately long, solid,
conical, and straight to somewhat inclined inwards, their
length 3.2–4.4 times median thickness of ischiopubic bar.
Iliac processes massive and curving inwards, with broad, qua-
drangular tip. Each iliac region with two foramina.
Fig. 14 Bathyraja arctowskii,
ZMH 120216, primary adult
male, 533 mm TL, tail end with
dorsal fins and low epichordal
caudal lobe. Scale bar: 2 cm
Fig. 13 Bathyraja arctowskii,
ZMH 120216, primary adult
male, 533 mm TL, mid-section of
tail in lateral view. Scale bar: 2 cm
18 Page 16 of 27 Marine Biodiversity (2021) 51:18

Scapulocoracoid (Fig. 23). Left side elements were dissect-
ed of an adult male (a) and adult female (b), both ZMH
115243. Morphometrics and meristics of both elements are
given in Table 4.
Scapulocoracoids of many Bathyraja species show in gen-
eral an elongated rectangular appearance in lateral view, with
very asymmetrical anterior position of the mesocondyle.
Unlike the rather constant and often species-specific
scapulocoracoid features in many rajid and arhynchobatid
genera, with a marked sexual dimorphism in a few genera
(e.g., Psammobatis, see McEachran 1983,orNeoraja, see
Stehmann et al. 2008), a very different situation is found in
the genus Bathyraja. In this latter genus, the degree of intra-
specific variation of scapulocoracoid features is so great,
independent of eventual sexual dimorphism but probably
due to ontogenetic influences, that the investigation of just a
single scapulocoracoid is in no way representative or diagnos-
tic for a Bathyraja species.
Figure 23 demonstrates for B. arctowskii both aspects,
namely sexual dimorphism in overall shape, as well as distinct
intraspecific natural variation in number, shape, and arrange-
ment of postdorsal and postventral foramina. Elements of both
sexes show a solid horizontal anterior bridge separating the
anterior fenestra into a smaller anterior dorsal and an anterior
ventral fenestra.
The adult male’s element (Fig. 23a)showsamoderately
short rectangular shape, with almost horizontal concave dorsal
margin to the rounded rear corner, from which the nearly
straight posterior margin slopes to the metacondyle. Two large
postdorsal fenestrae are of similar size as the anterior dorsal
Fig. 17 Bathyraja arctowskii, ZMH 115243, left clasper glans opened.
Scale bar: 1 cm
Fig. 15 Bathyraja arctowskii, adult male from the Atlantic sector (not
retained), in fresh condition. Photograph taken and kindly provided by
K.-H. Kock
Fig. 16 Bathyraja arctowskii,MNHN1987–0232, adult male, 591 mm
TL, from the Indian Ocean sector, in fresh condition. Photograph taken
and kindly provided by Guy Duhamel
Marine Biodiversity (2021) 51:18 Page 17 of 27 18

fenestra. The anterior postdorsal fenestra is subcircular, lon-
ger, and higher than the adf, the posterior pdf is oblique nar-
rowly oval, somewhat higher than the anterior pdf but only
half as wide as the latter. The five much smaller postventral
foramina are a chain from about midlength of the
mesocondyle to near the metacondyle; the second and last of
these are larger than the remaining three small, rather pore-like
postventral foramina.
In contrast is the adult female’s element (Fig. 23b)ofmore
elongated and distinctly rectangular shape, with an almost
horizontal dorsal margin to a sharply marked rear corner,
and the posterior margin is deeply concave and steeply slop-
ing to the metacondyle. Much in contrast to the male’sele-
ment are the five postdorsal foramina, in that the anterior one
is a horizontally elongated fenestra being much longer than
each of the anterior dorsal and ventral fenestrae. However, a
stump at its lower edge indicates a former ligament bridge
separating vertically this fenestra into two smaller ones.
Level with its upper edge is a chain of three pore-like foram-
ina, and below these a somewhat larger diagonally oval fora-
men. The large first postventral fenestra is of similar size as
the anterior ventral fenestra, whereas the following three are
Fig. 18 Bathyraja arctowskii, ZMH 115243, dissected left clasper
skeleton. a,bcomplete terminal skeleton in adorsal and bventral
views; c,dterminal skeleton with dorsal terminal 1 and ventral terminal
cartilages removed in cdorsal and dventral views; e,fterminal skeleton in
opened views with eand without fdorsal terminal 1 cartilage. Scale bars:
1cm
Fig. 19 Bathyraja arctowskii, ZMH 120216, primary adult male,
533 mm TL, radiograph of cranium and snout in dorsal view
Fig. 20 Bathyraja arctowskii, ZMH 123230, primary adult female,
535 mm TL, radiograph of cranium and snout in dorsal view
18 Page 18 of 27 Marine Biodiversity (2021) 51:18

much smaller and a chain along the ridge between meso- and
metacondyle.
Pre-mesocondyle length in the male 38.0% of maximum
length and 58.7% of the post-mesocondyle length; in the fe-
male 25.6% and 35.7% respectively. Maximum length 1.3
times maximum height at scapular process in the male, 1.6
times in the female’selement.Heightatrearcorneris83.3%
of the maximum height in the male, 85.3% in the female. The
combined height of both anterior fenestrae is 37.4% of the
maximum height at scapular process and 28.8% of the ele-
ment’s maximum length in the male, 43.3% and 26.8% in
the female, respectively.
Skeletal meristics (from radiographs of all primary
specimens except for male embryo; Table 1). Trunk vertebrae
(Vtr): 30–37; predorsal tail vertebrae (Vprd): 66–80; terminal
tail vertebrae (Vterm, approximately): 23–40; total vertebrae
(Vtotal, approximately): 120–151; pectoral radials, left: 70–
89, right: 70–90; pelvic radials, left: 4 + 16–5 + 20, right: 4 +
17–5 + 19.
Egg capsule (Figs. 24,25 and 26, based on two egg cap-
sules cataloged under ZMH 9014 and one of the syntypes
cataloged under IRSNB 25 [orig. 3005]). Table 5provides
morphometrics of the two egg capsules at ZMH.
Both surfaces of blackish-brown egg capsule smooth, with
coverage of long, fine anchoring fibers. Extension of aprons
two thirds onto horns. Upper side of egg capsule strongly
convex, lower side moderately convex. Cross-section (anteri-
or and posterior horns) depressed.
Size:Bathyraja arctowskii is one of the smallest species of
the genus, reaching 61 cm TL. The largest recorded adult
females are in the Atlantic a 608 mm TL specimen from off
Elephant Island (ZMH 123243), in the Pacific a 610 mm TL
specimen from the Ross Sea (NMNZ P.037551), and in the
Indian Ocean a 555 mm TL specimen from Prydz Bay
(NMNZ P.041445). The largest recorded adult males are in
the Atlantic a 586 mm TL specimen from off King George
Island (ZMH 123089), in the Pacific a 600 mm TL specimen
from the Ross Sea (NMNZ P.042225), and in the Indian
Ocean a 591 mm TL specimen from Prydz Bay (MNHN
1987-0232). The largest examined juvenile male has
384 mm TL, examined subadult males range from 361 to
450 mm TL, examined late subadult males range from 461
to 495 mm TL. The smallest examined adult male (NMNZ
P.041394) has 490 mm TL. The size at hatching is about 12–
13 cm TL based on primary male embryo ZMH 9014 and the
smallest juvenile female examined in detail (ZMH 121822).
Molecular analyses: The tissue samples used for the
molecular analyses are listed in Table 6.Themaximum
likelihood analysis of the aligned NADH2 sequence data
confirm that Bathyraja arctowskii is a monophyletic line-
age that is distinct from all other Bathyraja species from
the region (Fig. 27). Phylogenetic inference based on the
aligned NADH2 data set suggests that B. arctowskii is
most closely related to a lineage of Bathyraja from the
region that most closely resembles B. eatonii (identified
as B. cf. eatonii in Fig. 27). The true Bathyraja eatonii
appears more closely related to B. irrasa. B. murrayi and
B. meridionalis (see Fig. 27). However, it is important that
not too much be made of the phylogenetic placements pre-
sented herein as the inference is based on a single mito-
chondrial gene (see Naylor et al. 2012). More reliable phy-
logenetic inferences would require an assessment based on
a large suite of mitochondrial and nuclear genes. The “take
home message”from the mitochondrial data presented is
that B. arctowskii, while being morphologically distinct,
also appears to be molecularly distinct—at least, at the
locus we have examined.
Fig. 22 Bathyraja arctowskii, ZMH 123230, primary adult female,
535 mm TL, radiograph of pelvic girdle in dorsal view. The cut pelvic
girdle was assembled digitally
Fig. 21 Bathyraja arctowskii, ZMH 120216, primary adult male,
533 mm TL, radiograph of pelvic girdle in dorsal view
Marine Biodiversity (2021) 51:18 Page 19 of 27 18

Fig. 23 Bathyraja arctowskii, ZMH 115243, dissected scapulocoracoids of aadult male and badult female. Scale bar: 1 cm
Fig. 24 Bathyraja arctowskii,
ZMH 9014, two egg capsules. a,b
egg capsule with near-term em-
bryo removed in adorsal and b
ventral views; c,dempty egg
capsule in cdorsal and dventral
views. Scale bar: 2 cm
18 Page 20 of 27 Marine Biodiversity (2021) 51:18

Distribution:Bathyraja arctowskii appears to be a wide-
ranging, circumantarctic species with its center of distribution
in the Atlantic sector of the Southern Ocean (Fig. 28). It is
known from off the South Shetland, Brabant, and Biscoe
Islands to the South-East Weddell Sea, from the Ross Sea in
the Pacific sector, and two specimens (MNHN 1987-0232 and
NMNZ P.041445) from Prydz Bay in the Indian Ocean sector
of the Southern Ocean. The known depth distribution is
0–1685 m but the species is mainly found between 126 and
810 m depth based on ZMH material (excluding one lot of six
specimens, ZMH 120223, from 0 to 140 m depth). Records
deeper than 810 m are based solely on specimens from the
NMNZ collection, indicating that the species possibly occurs
in greater depths in the Pacific sector, albeit this may only be
the result of differing fishery efforts in the respective depths.
Most of the specimens caught deeper than 810 m were adults
but adult specimens were also recorded from shallower depths
elsewhere and juveniles in turn were also recorded deeper than
810 m and even below 1000 m.
Remarks: The adult male generally corresponds well to the
females, juvenile and subadult males, as well as the male
embryo. The observed sexual dimorphism is typical for
skates: adult male with anterior disc margins more undulated,
alar thorns present, teeth with longer cusps and arranged in
parallel rows (vs. quincunx pavement pattern), and pelvic gir-
dle narrower with deeply (vs. slightly) concave posterior con-
tour of ischiopubic bar.
Possible ontogenetic changes between the subadults plus
adults (n= 4, 424–535 mm TL), juveniles (n= 6, 135–333
mm TL), and the male embryo (n= 1, 120 mm TL) are listed
in Table 7. In addition, the median tail thorns become smaller
and more widely spaced posteriorly in subadults and adults
and are generally wider-spaced in large juveniles to adults as
compared with small juveniles. Furthermore, the male embryo
differs from all other specimens in a narrower disc (width
51.7% TL vs. 61.3–66.0% TL).
Discussion
As shown in the “Introduction”section, Raja arctowskii repre-
sents a unique case in skate taxonomy as it was named based
only on three empty egg capsules. Therefore, it has remained
impossible to assign any specimens to this species, and the spe-
cies has remained a nomen nudum for a long time. The avail-
ability of a gravid female with egg capsules finally enabled to
resolve this issue. Since this female was not found for the present
study, other evidence was needed and found in the egg capsule
with a male near-term embryo. The egg capsule unambiguously
belongs to the same species as the empty syntype capsules and
agrees well with all other examined capsules. The embryo itself
corresponds well to all other examined specimens, juveniles and
adults, thus evidencing their identity. The availability of adult
male specimens further allowed for the generic assignment of the
species to Bathyraja, in which it is one of the smallest species.
Compared with its congeners in the Southern Ocean,
Bathyraja arctowskii is one of two smallest species reaching
only 61 cm TL and maturing at around 36–50 cm TL. It can
further be distinguished from its congeners by the—at least
partial—dark pigmentation of the mouth cavity and underside
of nasal curtain, which are light-colored in other species.
The only species in the region with similar maximum and
egg capsule sizes, B. murrayi (Günther, 1880), reaches a
slightly larger maximum size, i.e., 70 cm TL (Duhamel et al.
2005) and shows a white mouth cavity. Bathyraja arctowskii
further differs from B. murrayi in the absence of thorns on the
dorsal disc (Stehmann and Bürkel 1990): B. murrayi has a pair
of distinct pre- and postorbital thorns, two or three on midline
of nape, one or two on each shoulder, and usually one on mid-
shoulder (vs. no thorns on dorsal disc); smaller additional
Fig. 25 Bathyraja arctowskii, one of three empty syntype egg capsules,
IRSNB 25, in dorsal view (anterior to the right). Photograph kindly
provided by Olivier Pauwels, © IRSNB
Fig. 26 Bathyraja arctowskii, one of three empty syntype egg capsules,
IRSNB 25, in ventral view (anterior to the right). Photograph kindly
provided by Olivier Pauwels, © IRSNB
Marine Biodiversity (2021) 51:18 Page 21 of 27 18

Fig. 28 Map of the Southern Ocean, showing catch locations of
Bathyraja arctowskii: specimens listed under material examined (121
stations, 339 specimens; black spots, multiply overlapping), specimens
from Bigelow & Schroeder (1965: two stations, two specimens; green
spots), egg capsules from ZMH collection listed under material examined
(eight stations, 40 egg capsules; white spots, overlapping), syntype egg
capsules from IRSNB collection (three stations, three egg capsules; blue
spots). Cartographic base from Matsuoka et al. (2018)
Bathyraja
cf. GN 17862
Bathyraja
cf. GN 17864
Bathyraja
cf. GN 178 5
Bathyraja
cf. GN 17861
Bathyraja
sp. GN 17854
Bathyraja
cf. GN 17857
Bathyraja
cf. GN 17859
Bathyraja
cf. GN 15726
Bathyraja
cf. GN 17856
GN 17896
GN 17899
GN 17897
GN 17898
GN 15722
GN 15724
GN 15727
GN 17876
GN 17877
GN 17880
GN 17881
Bathyraja maccaini
GN 17865
Bathyraja maccaini
GN 17866
Bathyraja maccaini
GN 17875
Bathyraja maccaini
GN 17870
Bathyraja maccaini
GN 17871
Bathyraja maccaini
GN 17872
Bathyraja maccaini
GN 17874
Bathyraja maccaini
GN 15716
Bathyraja maccaini
GN 15719
Bathyraja maccaini
GN 15715
Bathyraja maccaini
GN 15717
0.001 substitutions/site
GN 15714
GN 15711
Bathyraja maccaini
GN 17868
Bathyraja maccaini
GN 17867
Bathyraja maccaini
GN 17869
Bathyraja maccaini
GN 15720
Fig. 27 Inferred phylogenetic
relationships among taxa
resulting from a Maximum
Likelihood analysis of aligned
NADH2 sequence data using the
General Time Reversible model,
modified to accommodate among
site rate variation (ASRV) and a
proportion of invariant sites (I)
estimated from the data. The fig-
ure clearly shows Bathyraja
arctowskii to represent a distinct
lineage
18 Page 22 of 27 Marine Biodiversity (2021) 51:18

thorns may be present in supraorbital, supra- and
interspiracular positions (vs. absent). Furthermore,
B. murrayi has a very rough dorsal disc with additional coarse
spinules and thornlets, particularly in large specimens, which
are absent in B. arctowskii. Additionally, B. murrayi is only
known from off the Kerguelen and Heard Islands, where
B. arctowskii apparently does not occur, and large specimens
tend to show a pair of (rarely more) light, dark-edged large
pseudo-ocellar blotches on inner pectorals and individuals
with solid or blotched broad dark ventral disc margins are
common. Also, the egg capsule is shorter but broader than
that of B. arctowskii (compare Figs. 24,25 and 26 with
Fig. 29). Measurements of nine egg capsules of B. murrayi
in the MNHN collection, kindly provided by Guy Duhamel,
Zouhaira Gabsi, and Jonathan Pfliger, indicate egg case
lengths (ECL) of 57.0–67.2 mm and maximum case widths
(MAW) of 40.6–48.6 mm. In B. arctowskii, ECL is 76.1–
77.55 mm and MAW 40.72–42.33 mm. The presence of in-
terspecific differences in the morphology of skate egg cap-
sules has also been shown in previous studies (e.g.,
Ishiyama 1958b; Treloar et al. 2006; Ebert and Davis 2007;
Ishihara et al. 2012; Porcu et al. 2017). Accordingly, egg
capsule morphology can be very useful for distinguishing be-
tween different skate species, allows conclusions to be drawn
on the habitat, and the capsule size also enables rough estima-
tions of the size of adult animals.
Bathyraja irrasa Hureau & Ozouf-Costaz, 1980 also appears
to be an allopatric species, only known from off the Kerguelen
and Heard Islands. It is a much larger species, reaching ~120 cm
TL (Weigmann 2016;Lastetal.2016b) to 140 cm TL (Duhamel
et al. 2005), maturing size 86.5–121 cm TL and size at hatching
17.8–21.4 cm TL, and egg case 113.8 mm (excl. horns) long and
73.6 mm wide following Ishihara et al. (2012)or9–10 cm long
according to Duhamel et al. (2005). Like B. arctowskii,B. irrasa
has a very rough dorsal disc but with disc margins and pelvic fins
narrowly smooth (vs. prickly). Furthermore, B. irrasa has a pair
of distinct preorbital thorns always present (vs. absent), addition-
al smaller supra-and/or postorbital thorns may occur (vs. absent),
and the number of median tail thorns is tendentially lower (9–23
vs. 19–30). Additionally, the ventral disc and pelvic fins are
predominantly dark brown with an irregular-shaped broad whit-
ish band from about mouth rearwards along two thirds of
midbody (vs. predominantly whitish).
Bathyraja maccaini Springer, 1971 is also a much larger
species, attaining ~120 cm TL, males maturing at ~94 cm TL
following Last et al. (2016b), and with egg case 156.6 mm
long and 80.0 mm wide (Ishihara et al. 2012). In contrast to
B. arctowskii,B. maccaini has a dorsal disc largely smooth
centrally in large specimens, with broad bands of spinules
around outer disc margins, along midbody and on tail, and
pectoral centers only loosely prickly even at small size. A pair
of large thorns is always present pre- and postorbitally and on
the shoulders (vs. absent) and the number of median tail thorns
is lower (9–15 vs. 19–30).
Bathyraja meridionalis Stehmann, 1987 is the largest
species in the region, reaching ~150 cm TL, males matur-
ing at 132–142 cm TL, females at ~140 cm TL according
to Last et al. (2016b) or attaining 158 cm TL, males ma-
turing at 115–130 cm TL, females at 113–125 cm TL
following Ebert (2016). In contrast to B. arctowskii,
B. meridionalis has a dorsal disc covered with scattered,
coarse, sharp prickles, more densely set only at anterior
disc margins, in a broad band along midbody, and along
sides of the tail. Pelvic fins largely smooth above (vs.
spinules present at the rear margin of posterior pelvic-fin
lobes) but ventrally a row of spinules scattered along
Fig. 29 Bathyraja murrayi,
MTUF 26165, Kerguelen Islands,
14 Jan 1985, egg capsule (egg
case length 59.8 mm, maximum
case width 43.6 mm) with near-
term embryo. Note thorns on
trunk pronounced already in em-
bryonic specimens. Photograph
taken and kindly provided by
Hajime Ishihara. Estimated scale
bar: 2 cm
Marine Biodiversity (2021) 51:18 Page 23 of 27 18

edges of tail origin (vs. smooth). Median trunk and tail
with a continuous row of 37–39 distinct thorns from nape
to first dorsal fin and a smaller thorn interdorsally; median
thorns on disc may be lost only in fully grown specimens
(vs. no thorns on disc and usually no thorns interdorsally).
Furthermore, the ventral surface, including pelvic fins and
tail, is plain dark grayish-brown (vs. predominantly
whitish).
Bathyraja eatonii (Günther, 1876) is the only congener
of B. arctowskii in the Southern Ocean with no thorns on
the dorsal disc or only 1 or 2 large median thorns on the
nape/shoulder. Bathyraja eatonii is a much larger species,
reaching ~126 cm TL, with size at hatching ~17.8 cm TL
and egg cases 11–12 cm long (Duhamel et al. 2005;Last
et al. 2016b). In contrast to B. arctowskii, large specimens
of B. eatonii are mostly smooth on dorsal disc, with bands
of fine and (with growth) coarser spinules along anterior
margins, parallel to posterior margins and along midbody
and tail; pectoral centers and pelvic fins usually smooth.
Furthermore, B. eatonii has fewer median tail thorns (8–
18 vs. 19–30).
Generic composition:Bathyraja currently contains 52 val-
id species. However, the four valid species presently assigned
to Rhinoraja Ishiyama, 1952 likely belong to the same genus
as the differentiation of both genera is questionable and solely
relies on the presence or absence of a segmented rostral carti-
lage (Weigmann 2016). Unpublished mitochondrial molecu-
lar data collected by GJPN indicates that at least two of the
four species of Rhinoraja,R. longicauda Ishiyama, 1952 and
R. taranetzi Dolganov, 1983, are deeply nested within the
genus Bathyraja,supportingWeigmann’s(2016) hypothesis
of congenerity. A list of the valid Bathyraja and Rhinoraja
species, updated from Weigmann (2016,2017) and consider-
ing Last et al. (2016a,b), can be found in Table 8.
Acknowledgments The authors are very grateful to Bernard Séret
(ICHTYO CONSULT) for morphometrics, meristics, and description notes
of the MNHN specimen and Jonathan Pfliger, Guy Duhamel, and Zouhaira
Gabsi (MNHN) for photographs and radiographs of this specimen, as well as
basic measurements and photographs of several egg capsules of B. murrayi.
Guy Duhamel also kindly granted permission to use his fresh photograph of
the MNHN specimen in the present publication. The authors are also very
grateful to Olivier Pauwels (IRSNB) for kindly granting permission to use
photographs of the syntype egg capsule IRSNB 25 in the present publication.
Lei Yang (FLMNH) generated the molecular data used in the study. The
authors further would like to thank Hajime Ishihara (W&I Associates Co.
Ltd., Japan) for providing an image of an egg capsule and embryo of
B. murrayi andgrantingpermissiontousethisphotographinthepresent
publication; Andrew Stewart, and Carl Struthers (NMNZ) for detailed data,
photographs, and tissue samples of specimens at NMNZ; Will White
(CSIRO) for sending tissue samples of Bathyraja cf. eatonii,B. eatonii,
B. irrasa,B. maccaini,andB. murrayi; and Jürgen Pollerspöck (Shark-
References) for providing references. The second author is also very grateful
to Ralf Thiel (ZMH) for granting access to and loan of specimens in the ZMH
collection for examinations and access to photo- and radiography facilities at
ZMH, as well as for approving dissections of disintegrated specimens, and
Table 8 Valid species of Bathyraja and Rhinoraja
Scientific name Species authorship
Bathyraja abyssicola (Gilbert, 1896)
Bathyraja aguja (Kendall & Radcliffe, 1912)
Bathyraja albomaculata (Norman, 1937)
Bathyraja aleutica (Gilbert, 1896)
Bathyraja andriashevi Dolganov, 1983
Bathyraja arctowskii (Dollo, 1904)
Bathyraja bergi Dolganov, 1983
Bathyraja brachyurops (Fowler, 1910)
Bathyraja cousseauae Díaz de Astarloa & Mabragaña, 2004
Bathyraja diplotaenia (Ishiyama, 1952)
Bathyraja e atonii (Günther, 1876)
Bathyraja fedorovi Dolganov, 1983
Bathyraja griseocauda (Norman, 1937)
Bathyraja hesperafricana Stehmann, 1995
Bathyraja interrupta (Gill & Townsend, 1897)
Bathyraja irrasa Hureau and Ozouf-Costaz, 1980
Bathyraja ishiharai Stehmann, 2005a
Bathyraja isotrachys (Günther, 1877)
Bathyraja l eucomela nos Iglésias & Lévy-Hartmann, 2012
Bathyraja lindbergi Ishiyama & Ishihara, 1977
Bathyraja longicauda (de Buen, 1959)
Bathyraja maccaini Springer, 1971
Bathyraja macloviana (Norman, 1937)
Bathyraja maculata Ishiyama & Ishihara, 1977
Bathyraja magellanica (Philippi, 1902)
Bathyraja mariposa Stevenson et al. 2004
Bathyraja matsubarai (Ishiyama, 1952)
Bathyraja meridionalis Stehmann, 1987
Bathyraja microtrachys (Osburn & Nichols, 1916)
Bathyraja minispinosa Ishiyama & Ishihara, 1977
Bathyraja multispinis (Norman, 1937)
Bathyraja murrayi (Günther, 1880)
Bathyraja pacifica Last et al. 2016c
Bathyraja pallida (Forster, 1967)
Bathyraja panthera Orr, Stevenson, Hoff, Spies &
McEachran, 2011
Bathyraja papilionifera Stehmann, 1985
Bathyraja parmifera (Bean, 1881)
Bathyraja peruana McEachran & Miyake, 1984
Bathyraja richardsoni (Garrick, 1961)
Bathyraja scaphiops (Norman, 1937)
Bathyraja schroederi (Krefft, 1968b)
Bathyraja shuntovi Dolganov, 1985
Bathyraja simoterus (Ishiyama, 1967)
Bathyraja smirnovi (Soldatov & Pavlenko, 1915)
Bathyraja smithii (Müller & Henle, 1838)
Bathyraja spinicauda (Jensen, 1914)
Bathyraja spinosissima (Beebe & Tee-Van, 1941)
Bathyraja trachouros (Ishiyama, 1958a)
Bathyraja trachura (Gilbert, 1892)
Bathyraja tunae Stehmann, 2005b
Bathyraja t zinovskii Dolganov, 1983
Bathyraja violacea (Suvorov, 1935)
Rhinoraja kujiensis (Tanaka, 1916)
Rhinoraja longicauda Ishiyama, 1952
Rhinoraja odai Ishiyama, 1958a
Rhinoraja taranetzi Dolganov, 1983
18 Page 24 of 27 Marine Biodiversity (2021) 51:18

Irina Eidus (ZMH) for her help with the radiography, collection database and
cards, as well as for providing photographs of several specimens. The authors
are grateful to journal editors and reviewers of the manuscript for their helpful
comments.
Funding This work was supported (in part) by the NZ National Institute of
Water and Atmospheric Research Ltd. Core Funded Coasts & Oceans
Programme 2: Biological Resources subcontract for fundamental knowledge
of marine fish biodiversity with the Museum of New Zealand Te Papa
Tongarewa. The collection of sequence data was supported with an award
from the U.S. NSF Foundation to GJPN, DEB 01132229.
Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of
interest.
Ethical approval All applicable international, national, and/or institu-
tional guidelines for animal testing, animal care, and use of animals were
followed by the authors.
Sampling and field studies All necessary permits for sampling and
observational field studies have been obtained by the authors from the
competent authorities and are mentioned in the acknowledgements, if
applicable. The study is compliant with CBD and Nagoya protocols.
Data availability All data generated or analyzed during this study are
included in this published article.
Author contribution MFWS and SW conceived and designed research,
conducted examinations, and wrote the first draft of the manuscript,
GJPN conducted molecular analyses and contributed parts of the manu-
script. All authors read and approved the final manuscript.
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Key to the valid species of Bathyraja in the Southern Ocean:
1. Underside of disc largely or entirely dark, may become paler in large individuals ................................................................... 2
–Underside of disc white or largely so ....................................................................................................................................... 3
2. Underside totally dark with small white marks only at nostrils, jaws, gills, tip of anterior pelvic lobe and tail origin; median
row of about 40 thorns from nape to D1, but ~10 on disc often lost in adults; the largest species in the region, reaching ~150–
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3. Orbital and shoulder thorns always present .............................................................................................................................. 4
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4. Upper disc very rough with scattered coarse prickles and thornlets; thorns at orbits, on nape and shoulders. 21–26 distinct
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4–5 cm wide .............................................................................................................................................................. B. murrayi
–Upper disc partly prickly along margins,on midbody, and on tail; a massive thorn only in front of and behindeach eye and on
each shoulder; 8–15 median thorns only along tail; pectoral centers mostly smooth; reaches ~120 cm TL, egg cases ~16 cm
long and 8 cm wide ................................................................................................................................................. B. maccaini
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pectoral centers and rear margins smooth; 8–18 small median thorns along tail; mouth cavity white; attains ~126 cm TL, egg
cases 11–12 cm long ................................................................................................................................................... B. eatonii
–No thorns on upper disc, which is totally prickly; 19–3 small median thorns along tail; mouth cavity and underside of nasal
curtain partly or totally pigmented dark; reaches ~61 cm TL, egg cases ~6–7 cm long .................................... B. arctowskii
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