A review of the genus Dysalotus (Percomorphacea: Chiasmodontidae), with the description of Dysalotus pouliulii sp. nov

Abstract

A new species of Dysalotus (family Chiasmodontidae) known only from off the Hawaiian archipelago is described here as Dysalotus pouliulii sp. nov. It differs from all other species of Dysalotus in having a greater number of teeth on the premaxilla (151–198 v . 60–138) and dentary (136–199 v. 76–132) and in a shorter upper jaw [51·9–54·9% of head length ( L H ) v. 62·4–74·4% L H ] and lower jaw (64·8–67·4% in L H v. 75·3–88·1% in L H ). A key for the species of Dysalotus and an updated distribution map are provided.
http://zoobank.org/urn:lsid:zoobank.org:pub:E9B5F1DC‐52E0‐4F53‐9109‐2A8E252AE8CE .

Full text

Journal of Fish Biology (2017)
doi:10.1111/jfb.13194, available online at wileyonlinelibrary.com
A review of the genus Dysalotus (Percomorphacea:
Chiasmodontidae), with the description of Dysalotus
pouliulii sp. nov.
M. R. S. M*
Departamento de Oceanograa Biológica, Instituto Oceanográco, Universidade de São
Paulo, Praça do Oceanográco, 191, São Paulo, SP, 05508-120, Brazil
urn:lsid:zoobank.org:pub:E9B5F1DC-52E0-4F53-9109-2A8E252AE8CE
(Received 15 January 2016, Accepted 26 September 2016, Published online 13 January
2017)
A new species of Dysalotus (family Chiasmodontidae) known only from off the Hawaiian archipelago
is described here as Dysalotus pouliulii sp. nov. It differs from all other species of Dysalotus in
having a greater number of teeth on the premaxilla (151– 198 v. 60 – 138) and dentary (136 –199 v.
76– 132) and in a shorter upper jaw [51·9–54·9% of head length (LH)v. 62·4–74·4% LH]andlower
jaw (64·8–67·4% in LHv. 75·3–88·1% in LH). A key for the species of Dysalotus and an updated
distribution map are provided.
© 2016 The Fisheries Society of the British Isles
Key words: bathypelagic; deep sea; Hawaiian Archipelago; taxonomy.
INTRODUCTION
Dysalotus MacGilchrist 1905 is a very distinctive member of the deep-sea sh fam-
ily Chiasmodontidae and can be easily recognized within the family by the presence
of enlarged, conspicuous prickles on the posterior half of the body, a ventral chin
knob at the symphysis of the dentaries and a supramaxilla (Johnson & Cohen, 1974;
Melo, 2008, 2009, 2010). The genus Dysalotus was erected by MacGilchrist (1905) to
accommodate Dysalotus alcocki MacGilchrist 1905. Later, Norman (1929) described
Dysalotus macrodon, but it was subsequently placed in the genus Kali Lloyd 1909
(Smith, 1965; Johnson, 1969; Melo, 2008). Johnson & Cohen (1974), mostly using
material collected by the German R.V. Walter Herwig in the Atlantic Ocean, revised
the genera Kali and Dysalotus, describing Dysalotus oligoscolus Johnson & Cohen
1974 and providing comprehensive osteological descriptions for both genera.
Here, the species of Dysalotus are taxonomically revised and diagnosed based on
putatively unique characteristics. Both D.alcocki and D.oligoscolus are considered
valid and a new species is described as Dysalotus pouliulii sp. nov. Dysalotus alcocki
and D.oligoscolus are widely distributed in the Atlantic, Indian and Pacic Oceans and
may occur in sympatry, but the rst is more common in lower latitudes, from 40∘Nto
21∘30′S and the latter in higher latitudes, up to 49∘N and 40∘S (Melo & Stewart,
2015). Dysalotus pouliulii is extremely rare in scientic collections and is only known
Tel.: +55 11 3091 6628; email: melomar@usp.br
1
© 2016 The Fisheries Society of the British Isles

2M. R. S. MELO
from two specimens, collected in different localities off the Hawaiian Archipelago. A
key for the species of Dysalotus and an updated distribution map are provided.
MATERIALS AND METHODS
Morphometric and meristic data were obtained following the protocols described by
Melo et al. (2007) and Melo (2008). Meristic counts, presented in the text, are followed by
their frequencies in parentheses. Terminology for tooth arrangements follows Melo (2010).
Measurements were recorded to the nearest 0·1 mm using digital callipers. Vertebral counts
were made from cleared and stained or X-rayed specimens. True spines (sensu Johnson &
Patterson, 1993) were counted and are reported in uppercase Roman numerals; unbranched
soft rays are represented in lowercase Roman and branched soft rays in Arabic numerals.
The counts for soft rays of the second dorsal, anal and pectoral ns are given as total counts
because their tips were often broken, making it impossible to differentiate as either branched
or unbranched. Johnson & Cohen’s (1974) distinction between emergent and non-emergent
prickles (i.e. cutaneous and subcutaneous, respectively) was followed to avoid confusion. The
holotype of Dysalotus alcocki (ZSI F 1053/1) was examined through photographs.
Classication of Atlantic Ocean biogeographic regions follows Backus et al. (1977), with
the addition of the Atlantic sub Antarctic Province to the region between the South Atlantic
subtropical and Guinean Provinces and the Southern Ocean. Classication for the Indian and
Pacic Oceans follows Springer (1982).
General abbreviations include: LS, standard length; LH, head length; CS; cleared and stained;
R.V., research vessel; R.R.S., royal research ship; R.I.M.S., royal Indian marine survey ship.
Institutional abbreviations include: AMS, Australian Museum (Sydney, Australia); BMNH,
British Museum of Natural History Museum (London, U.K.); CBM-ZF, Natural History
Museum and Institute (Chiba, Japan); CAS, California Academy of Sciences (San Francisco,
CA, U.S.A.); FMNH, Field Museum of Natural History (Chicago, IL, U.S.A.); ISH, Bundes-
forschungsinstitut für Ländliche Räume, Institut für Seescherei (Hamburg, Germany); SIO,
Scripps Institution of Oceanography (La Jolla, CA, U.S.A.); LACM, Natural History Museum
of Los Angeles County (Los Angeles, CA, U.S.A.); LSU, Louisiana State University (Baton
Rouge, LA, U.S.A.), MCZ, Museum of Comparative Zoology, Harvard University (Cambridge,
MA, U.S.A.); HUMZ, The Hokkaido University Museum (Hakodate, Japan); MNRJ, Museu
Nacional, Universidade Federal do Rio de Janeiro (Rio de Janeiro, Brazil); NSMT-P, National
Museum of Nature and Science (Tsukuba, Japan); UF, University of Florida, Florida Museum
of Natural History (Gainesville, FL, U.S.A.); USNM, National Museum of Natural History,
Smithsonian Institution, (Washington D.C., U.S.A.); UMML, University of Miami (Miami,
FL, U.S.A.); ZMH, Zoologisches Institut und Zoologisches Museum der Humboldt Universität
(Hamburg, Germany); ZMUC P., Zoologisk Museum, Københavns Universitet (Copenhagen,
Denmark); ZSI F, Zoological Survey of India (Kolkata, India).
RESULTS
DYSALOTUS MACGILCHRIST 1905 THORNY SWALLOWERS
Dysalotus MacGilchrist 1905: 267–270 (type by original designation; type species:
Dysalotus alcocki MacGilchrist 1905; gender: male).
Diagnosis
The genus Dysalotus can be readily distinguished from Chiasmodon Johnson 1864,
Kali and Pseudoscopelus Lütken 1892 by four unique characteristics: enlarged and
conspicuous prickles on posterior half of body in adults present (v. enlarged, conspic-
uous prickles absent in species of Kali and Pseudoscopelus; or small, non-pungent
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

REVIEW OF DYSALOTUS 3
spinules present in specimens >45·0mminLSof all species of Chiasmodon and adults
of C.pluriradiatus and C.asper); a chin knob projecting ventrally at symphysis of
dentaries (v. knob absent); a supramaxilla present (v. absent). Dysalotus can be further
diagnosed osteologically by a combination of vertebral counts: total vertebrae 38– 40,
precaudal vertebrae 15–17 (v. total vertebrae 42–48, precaudal vertebrae 19–25 in
species of Chiasmodon; total vertebrae 33–40, precaudal vertebrae 20–26 in species of
Kali; total vertebrae 31–38, precaudal vertebrae 14–19 in species of Pseudoscopelus).
Dysalotus is further distinguished from Chiasmodon and Pseudoscopelus by the fol-
lowing characteristics: cranial bones fragile, with trabeculae easily distinguishable (v.
cranial bones compact, with undistinguishable trabeculae); nasal weakly calcied, cir-
cular but not spoon-shaped, dorsal in snout and covered by pigmented skin (v. nasal
strongly calcied, spoon-shaped, lateral in snout and covered by thin transparent skin);
parietals small, less than half the length of supraoccipital (v. parietals enlarged, or same
length or a little smaller than supraoccipital); pre- and postzygapophyses absent (v.
present); elongate supercial neuromasts larger than 2·0 mm absent (v. elongated super-
cial neuromasts larger than 2·0 mm present on head and body); last pored lateral-line
scale contiguous with penultimate scale (v. last pored scale of lateral line well separated
from the penultimate scale and positioned on lower lobe of the caudal n); caudal-n
rays ii +6+7+ii, or ii +7+7+ii (v. caudal-n rays i +7+8+i).
Dysalotus is further distinguished from Kali by having the dentary and premaxillary
teeth arranged in bands of up to ve or seven rows (v. premaxillary and dentary teeth in
two rows exclusively); teeth needle-like, straight, with anterior attachment to bone type
4sensu Fink (1981) (v. teeth in mesial row strikingly recurved, with ventral attachment
to bone) and branchiostegal rays seven (v. six).
Description
Greatest body depth at origin of rst dorsal n. Lateral line complete, extending
from post-temporal to medial caudal-n rays; one pore per scale. Emergent prickles
well developed, on posterior half of body, in one to four rows dorsal and ventral to
lateral line; subcutaneous prickles present or absent. Prickles formed by reduced scales,
lacking circuli and radii (Pietsch, 1989: 262, gure 5H).
Anterior prole of head elongate, triangular in lateral view, slightly concave dorsally.
Snout pointed. Bones of head fragile, bone trabeculae visible with naked eye. Head
with cavernous appearance, with dorsal concavity at level of braincase medially and
well developed crests in frontals, extending laterally to concavity in posterior part of
cranium and converging at level of posterior naris; foramina of sensorial system of head
wide. Lower jaw projecting anteriorly to upper jaw; medial ventral knob at symphysis
of dentaries present. Orbit circular, eye well developed. Nares lateral and distinctly
separated; anterior naris circular, posterior naris oval.
Pectoral n well developed, not reaching the level of anus; pectoral-n insertion
lateral on body, posterior to angle of opercle; all pectoral-n rays soft. Pelvic-n origin
slightly anterior to vertical through origin of pectoral n, ventral on body; lateral-most
ray a true spine, other medial rays soft. Two discrete dorsal ns. First dorsal-n origin
slightly posterior to vertical through base of pectoral n; all true spines; second dorsal-
n origin slightly posterior to vertical through anal n origin; all rays soft. Anal n elon-
gate, origin immediately posterior to anus; all rays soft. Caudal n forked, all rays soft.
Gill arches four; pseudobranchae present. Proximal half of rst epibranchial con-
nected to internal part of opercle; ceratobranchial and hypobranchial of rst arch free.
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

4M. R. S. MELO
90°
45°
0°
45°
90°
135° 90° 45° 0° 45° 90° 135°
N
F. 1. Known distribution of Dysalotus spp.: ,D. alcocki; , D. oligoscolus; , D. pouliulii. , , , capture
localities for type specimens. Each symbol on map may represent more than one locality.
Epibranchials of second, third and fourth arches connected to each other and to the
infrapharyngobranchials; ceratobranchial of second arch free. Hypobranchial and basi-
branchial of second and third arches connected to each other and to basibranchial of
fourth arch. Ceratobranchial of third and fourth arches connected; ceratobranchial of
fourth arch connected by skin to body wall at anterior half; gill slit present between
fourth ceratobranchial and body.
Colour
Preserved specimens dark brown; specimens sometimes faded to light brown to com-
pletely bleached. MacGilchrist (1905) reported a violet-black colour in life for Dysa-
lotus alcocki and C. Kenaley (pers. comm.) reported a pink esh.
Distribution
The species of Dysalotus are widely distributed in the Atlantic, Pacic and Indian
Oceans (Fig. 1).
Remarks
Johnson & Cohen (1974: 34) described Dysalotus oligoscolus as having a ‘slight
symphyseal knob or none at all’. The knob, however, was present in all specimens of
D.oligoscolus examined for this revision, including the holotype and all specimens
examined used for the original description. Therefore, the chin knob is considered to
be a good diagnostic characteristic and a putative synapomorphy for the genus.
DYSALOTUS ALCOCKI MACGILCHRIST 1909 [FIGS 2(A), (B),
3(A) AND 4(A), AND TABLE 1)
Dysalotus alcocki MacGilchrist 1905: 268– 270 (original description; type locality:
India, 10∘06′N; 92∘29′E, 705 fathoms (1289 m); holotype: ZSI F 1053/1). Norman,
1929: 541–542, gure 9 (key for the species, record in the South Atlantic and Bay
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

REVIEW OF DYSALOTUS 5
F. 2. (a) Dysalotus alcocki, ZSI F 1053/1, c. 200 mm standard length (LS), holotype (photograph courtesy of
S. Ferdous); (b) Dysalotus alcocki, USNM 207603, 207·1mmLS;(c)Dysalotus oligoscolus, ZMH 24975,
117·0mmLS, paratype; (d) Dysalotus pouliulii, FMNH 88135, 160·7mmLS, holotype; (e) Dysalotus pouli-
ulii, HUMZ 130474, 157·1mmLS, paratype.
of Bengal). Norman, 1930: 349 (checklist). Grey, 1966: 193–194 (depth record
from South Atlantic). Johnson & Cohen, 1974: 14–32, gures 1– 7, 9 – 10, tables
1–4 (taxonomic revision, osteological description). Johnson & Keene, 1986: 732,
gure 1b, 228·3 (key for the species, species account based on literature record).
Johnson & Keene, 1990: 901 (checklist of shes from eastern North Atlantic). Fricke,
1999: 462 (checklist of shes from the Mascarene Islands, Indian Ocean; expected
record). Randall & Lim, 2000 (checklist of shes from China). Mooi & Paxton,
2001: 3495–3496 (checklist of shes from western-central Pacic Ocean). Nakabo,
2002: 1073 (key to species). McEachran & Sutton, 2003: 142– 143 (checklist of
shes from western-central Atlantic Ocean). Moore et al., 2003: 227 (checklist of
shes from off New England, U.S.A.). Mundy, 2005 (checklist of shes from Hawaii).
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

6M. R. S. MELO
F. 3. X-ray of posterior half of body to illustrate the distribution of prickles in Dysalotus spp. (a) Dysalo-
tus alcocki, USNM 207603, 207·1 mm standard length (LS); (b – d) Dysalotus oligoscolus, ZMH 24975,
117·0mm LS, paratype, USNM 207607, 206·9mm LS, paratype, USMN 207612, 81·6mm LS, paratype,
respectively; (e) Dysalotus pouliulii, FMNH 88135, 160·7mmLS, holotype.
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

REVIEW OF DYSALOTUS 7
F. 4. Schematic representations of dentition pattern in (a, c) premaxilla; (b, d) dentary of (a, b) Dysalotus
alcocki, based on CBM-ZF 10457, 138·8 mm standard length (LS); (c, d) D. pouliulii, based on HUMZ
130474, 157·1mmLS, paratype.
Shinohara et al., 2005: 437 (checklist of shes from Ryukyu Islands, Japan). Prokoev,
2011: 698–702, Figs 2 and 3 and Table I (records from Taiwan, Hawaiian– Emperor
seamount chain and Eastern Indian Ocean).
Material examined
Atlantic Ocean: CAS 27550 (1, 49·4mmLS), western North Atlantic, north Sargasso
Sea, Bermuda, 32∘12′N; 64∘36′W, 1280 m, 6 February 1930, W. Beebe col.; MCZ
60760 (1, 37·0mm LS), western North Atlantic, south Sargasso Sea, Bahamas, 26∘21′
N; 78∘46′W, 12 October 1983; R.V. Iselin; MCZ 60722 (1, 34·3mm LS), western
North Atlantic Ocean, slope water, 39∘28′N; 64∘36′W, 800–1000 m, 2 October 1984,
R.V. Knorr; MCZ 65494 (1, 29·8mmLS), western North Atlantic Ocean, slope water,
36∘04′N; 71∘29′W, 746 – 1001 m, 19 August 1982, R.V. Oceanus; MCZ 163223
(1, 42·4mm LS), western North Atlantic Ocean, slope water, 39∘54′N; 67∘33′W,
16 May 2003, R.V. Delaware; MNRJ 26733 (1, c. 190·0mm LS; partially destroyed),
western South Atlantic Ocean, South Atlantic Ocean subtropical, off Rio de Janeiro,
Brazil, 21∘28′S; 39∘47′W, 1594 – 1614 m, 7 July 2000, R.V. Thalassa; UF 106427
(1, 105·6mm LS), western North Atlantic Ocean, Caribbean Sea, off Panama, 9∘24′
48′′ N; 78∘12′42′′ W, 51 m, 19 July 1966, R.V. Pillsbury; UF 158785 (1, 69·8mmLS),
western North Atlantic Ocean, South Sargasso Sea, Bahamas, 22∘38′00′′ N; 75∘18′
24′′ W, 2250 m, 24 July 1971, R.V. Pillsbury; UF 181714 (1, 150·0mm LS), western
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

8M. R. S. MELO
T I. Morphometric characteristics of Dysalotus alcocki,D. oligoscolus and D. pouliulii
D.alcocki D.oligoscolus D.pouliulii
Characteristic Range (mean, .., n) Range (mean, .., n) Holotype Paratype (mean, ..)
Standard length (LS, mm) 49·4–211·0 (140·1, 46·9, 18) 49·6–254·6 (164·1, 65·5, 17) 160·7 157·1
Head length (LH, mm) 16·0–56·6(38·9, 11·3, 18) 15·8–67·5(45·0, 16·2, 17) 44·942·3
%ofLH
Snout 9·5–13·7(10·8, 1·1, 18) 8·5–12·9(10·7, 1·0, 16) 10·79·5(10·1, 0·8)
Upper jaw 57·2–69·2(63·4, 3·4, 18) 64·4–74·4(69·5, 2·8, 16) 54·951·9(53·4, 2·2)
Lower jaw 72·3–81·4(77·6, 2·7, 17) 73·4–88·1(81·9, 3·7, 16) 64·867·4(66·1, 1·8)
Orbit width 9·9–14·9(12·2, 1·3, 18) 10·7–16·0(13·2, 1·5, 17) 14·710·9(12·8, 2·7)
Orbit height 8·9–12·2(10·6, 1·1, 15) 8·9–13·7(11·4, 1·7, 17) 12·412·2(12·3, 0·1)
Anterior nostril to eye 12·1–17·1(15·4, 1·1, 18) 8·8–15·3(12·7, 1·6, 16) 13·713·7(13·7, 0)
Posterior nostril to eye 6·7–11·4(9·6, 1·2, 18) 4·0–9·2(7·2, 1·4, 16) 6·98·3(7·6, 1·0)
Distance between nostrils 1·8–3·8(2·7, 0·5, 18) 0·9–4·2(2·9, 0·8, 16) 3·23·4(3·3, 0·1)
Interorbital distance 23·5–27·4(25·4, 1·3, 18) 20·1–26·2(23·8, 1·6, 17) 22·424·3(23·4, 1·3)
Head width 31·5–37·0(34·7, 1·7, 16) 27·7–36·4(32·7, 2·3, 16) 35·933·5(34·7, 1·7)
Cheek depth 5·6–10·5(7·6, 1·3, 18) 3·6–8·0(6·0, 1·1, 17) 6·07·2(6·6, 0·8)
%ofLS
Head length 26·1–32·4(28·3, 1·9, 18) 24·5–32·6(28·1, 2·6, 17) 27·926·9(27·4, 0·7)
Body width 3·9–9·6(5·9, 1·3, 18) 2·5–7·4(5·2, 1·2, 17) 7·16·0(6·6, 0·8)
Insertion of pectoral n 29·1–37·0(31·5, 2·3, 18) 26·5–35·4(30·6, 2·6, 17) 31·629·7(30·7, 1·3)
Insertion of pelvic n 29·1–38·9(31·9, 2·4, 18) 28·4–37·8(31·5, 2·3, 17) 32·530·3(31·3, 1·6)
Pectoral-n length 12·0–17·5(13·6, 1·5, 18) 11·6–17·0(14·4, 1·7, 16) 14·613·5(14·1, 0·6)
Pelvic-n length 5·5–10·2(8·4, 1·3, 18) 6·1–10·9(9·0, 1·7, 17) 8·79·5(9·1, 0·6)
Origin of rst dorsal n 29·4–38·6(34·0, 1·9, 18) 30·5–38·4(34·4, 2·2, 17) 32·033·0(32·5, 0·7)
Base of rst dorsal n 12·4–17·2(15·7, 1·4, 15) 12·8–22·1(17·5, 2·3, 17) 16·119·2(17·7, 2·2)
First dorsal-n depth 5·2–11·6(9·5, 2·0, 10) 7·1–10·9(9·1, 1·3, 6) NA NA
Origin of second dorsal n 48·0–55·5(52·2, 1·9, 18) 49·8–55·7(53·4, 1·7, 17) 51·251·9(52·9, 0·4)
Base of second dorsal n 37·4–43·0(40·8, 1·8, 15) 35·7–41·5(39·0, 1·4, 12) 40·536·1(38·3, 3·1)
Second dorsal-n depth 9·3–17·6(13·7, 2·7, 14) 10·2–20·9(13·4, 3·6, 8) NA NA
Origin of anal n 48·3–54·4(51·1, 1·9, 18) 49·2–55·1(52·3, 1·8, 17) 48·053
·9(50·9, 4·2)
Base of anal n 33·4–44·3(41·2, 2·7, 15) 36·3–41·1(39·2, 1·4, 12) 39·138·1(38·6, 0·7)
Anal-n depth 9·9–20·6(12·9, 3·5, 10) 9·8–14·4(11·9, 1·5, 7) 15·7NA(15·7, NA)
Peduncle depth 2·8–3·8(3·3, 0·3, 18) 2·7–4·0(3·3, 0·4, 17) 3·74·1(3·9, 0·3)
Peduncle length 6·9–10·5(8·1, 0·9, 15) 7·5–9·9(8·8, 0·8, 12) 7·810·3(9·1, 1·8)
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

REVIEW OF DYSALOTUS 9
North Atlantic Ocean, Gulf of Mexico, off Alabama, U.S.A., 28∘45′N; 88∘22′W,
7 May 1997, R.V. Chapman; UF 216120 (former UMML 16120, 1, 43·0mm LS),
eastern South Atlantic Ocean, Guinean Province, off Ghana, 4∘56′N; 00∘13′E,
1650– 2125 m, 27 May 1964, R.V. Pillsbury; UF 216141 (former UMML 16141, 1,
39·1mmLS), eastern South Atlantic, Guinean Province, off Ghana, 3∘50′N; 2∘37′W,
0–750 m, 29 May 1964, R.V. Pillsbury; UF 216529 (former UMML 16529, 1, 62·9mm
LS), eastern South Atlantic Ocean, Guinean Province, off Ghana, 5∘02′N; 00∘12′E,
3047–3129 m, 26 May 1964, R.V. Pillsbury; USNM 207603 (2, 145·2– 207·1mmLS),
eastern South Atlantic Ocean, Guinean Province, 7∘32′N; 20∘54′W, 0 – 1300 m, 14
April 1971, R.V. Walter Herwig; ZMH 109819 (former ISH 2318-1971, 1, 184·1mm
LS), North Atlantic Ocean, 1∘04′N; 18∘22′W, 12 April 1971; R.V. Walter Herwig;
ZMH 112587 (former ISH 459-1974, 1, 87·4mm LS), North Atlantic Ocean, 3∘
32·5′N; 38∘00′W, 23 July 1974, R.V. Walter Herwig; ZMH 117471 (former ISH
1126-1979, 1, 154·3mm LS), North Atlantic Ocean, 25∘8′N; 67∘50′W, 11 April
1979, R.V. Walter Herwig; ZMH 117472 (former ISH 1229-1979, 1, 147·5mm LS),
North Atlantic Ocean, 30∘27′N; 66∘08′W 15 April 1979, R.V. Walter Herwig;ZMH
117474 (former ISH 1499-1979, 1, 144·6mm LS), North Atlantic Ocean, 28∘41′N;
60∘54′W, 20 April 1979, R.V. Walter Herwig; ZMH 117475 (former ISH 1654-1979,
1, 160·3mm LS), North Atlantic Ocean, 27∘38′N; 52∘22′W, 23 April 1979, R.V.
Walter Herwig; ZMH 117477 (former ISH 904-1979, 1, 143·3mmLS), North Atlantic
Ocean, 24∘41′N; 66∘20′W, 10 April 1979, R.V. Walter Herwig; ZMUC P. 658 (1,
176·1mm LS), western North Atlantic Ocean, Lesser Antillean Province, off Santa
Lucia, 13∘47′N; 61∘26′W, 24 November 1921, R.V. Dana; ZMUC P. 6584 (1,
160·7mm LS), central South Atlantic Ocean, Guinean Province, 10∘57′S; 11∘20′W,
7 April 1971, R.V. Walter Herwig; ZMUC P. 6585 (1, 161·6mm LS), collected with
USNM 207603; ZMUC P. 6586 (1, 210·8mm LS), collected with USNM 207603.
Indian Ocean: SIO 61-31-60 (1, 78·4mm LS), Eastern Indian Ocean, Java Trench,
off Bali & Lombals, Indonesia, 12∘05′S; 115∘26′E, 0– 2000 m, R.V. Argo;ZSIF
1053/1 (holotype, 200 mm LS), 10∘06′N; 92∘29′E, 705 fathoms (1289 m), 12 April
1903, R.I.M.S. Investigator Sta. 315. Pacic Ocean: CBM-ZF 10457 (1, 138·8mm
LS), western North Pacic Ocean, Philippines sea, Great Basin Trough, 17∘03′02′′
N; 130∘00′03′′ E, 10 November 1981; FMNH 88134 (1, 118·2mmLS), central North
Pacic Ocean, off Leeward O′ahu, Hawaii, U.S.A., 21∘23′N; 158∘18′W, 1 August
1971, R. E. Young col.; MCZ 60806 (1, 107·3mm LS), western South Pacic Ocean,
Bismark Sea, off New Ireland, Papua New Guinea, 3∘11′S; 149∘51′E, 0 –2075 m,
9 February 1982, R.V. Lady Basten; MCZ 60807 (1, 86·6mm LS), western South
Pacic Ocean, Solomon Sea, off New Ireland, Papua New Guinea, 4∘49′S; 153∘18′
E, 2 February 1982, R.V. Lady Basten; MCZ 60808 (1, 163·0mmLS), western South
Pacic Ocean, Coral Sea, Australia, 11∘46′S; 145∘00′E, 0–1130 m, 30 November
1981, R.V. Lady Basten; MCZ 60809 (1, 44·9mm LS), western South Pacic Ocean,
Solomon Sea, New Britain Trench, Papua New Guinea, 6∘43′S; 152∘14′E, 1180 m,
23 May 1981, R.V. Lady Basten; NSMT-P 67078 (1, 143·9mm LS), western North
Pacic Ocean, East China Sea, Ryukyu Island, Japan, 26∘10′41′′ N; 125∘50′42′′
E, 2147–2164 m, 27 April 2002, R.V. Tansei-maru; SIO 60-130-60 (1, 142·3mm
LS), western central Pacic Ocean, Banaba Island, Kiribati, 0∘07′N; 169∘00′E,
0–2000 m, 1 December 1952, R.V. Horizon; SIO 60-234-60 (1, 186·6mmLS), central
Pacic Plate, 2∘21′S; 137∘16′W, 0 – 2500 m, 2 July 1960, R.V. Spencer F Baird;
SIO 70-346-60 (1, 147·9mm LS), western North Pacic Ocean, South China Sea,
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

10 M. R. S. MELO
Philippines, 14∘34′N; 119∘33′E, 0–1500 m, 19 September 1970, R.V. Melville;SIO
73-170 (1, c.92·0mm LS), central Pacic Plate, off Kiribati, 0∘02′N; 154∘55′W,
1280 m, R.V. Melville; SIO 76-164-60 (1, 137·0mmLS), western South Pacic Ocean,
Solomon Sea, Solomon Islands, 9∘25′S; 159∘06′E, 3 March 1975, R.V. Alpha Helix;
SIO 88-179 (1, 48·4mm LS), western North Pacic Plate, 7∘05′N; 176∘48′W, 2 0
March 1987, R.V. Atlantis II; USNM 207602 (1, 201·9mm LS), central North Pacic
Plate, north-west of Palmyra Atoll, U.S.A., 8∘00′N; 164∘33′W, 0 – 1400 m, 8 August
1963, R.V. Te Veg a ; ZMUC P. 6511 (1, 62·8mm LS), western South Pacic Ocean,
Banda Trench, Indonesia, 5∘36′S; 131∘05′E, 22 September 1951, R.V. Galathea.
Diagnosis
Dysalotus alcocki is distinguished from its congeners by the following combination
of characteristics: from D.oligoscolus by having three to ve rows of emergent prickles
dorsal and ventral to lateral line (v. emergent prickles arranged in two single rows, one
dorsal and one ventral to lateral line) and vomerine teeth absent (v. vomerine teeth
present); and from D.pouliulii, by having premaxillary teeth 75–117 (v. premaxillary
teeth 151–198) and dentary teeth 76– 126 (v. dentary teeth 136 – 199).
Description
Largest specimen examined 210·8mmLS. Morphometric data summarized in Table I.
General body shape as described for genus. Prickles present on posterior half of body
and caudal peduncle, irregularly distributed in three to four rows dorsal and ventral to
lateral line [Fig. 3(a)].
First dorsal-n rays VII (1), VIII (3), IX (4), X (10), XI (2); second dorsal-n rays
ii +23 (1), iv +20 (1), v +20 (1), iv +21 (2), iv +22 (2), iv +23 (2), v +23 (2), vii +21
(1); total rays in second dorsal n 22 (1), 23 (1), 24 (1), 25 (4), 26 (2), 27 (3), 28 (5),
29 (3); anal-n rays x +19 (1), iii +23 (1), v +21 (1), vi +21 (3), iv +23 (2), v +23
(1), vi +22 (1); total anal-n rays 24 (1), 26 (3), 27 (7), 28 (7), 29 (2); pectoral-n
rays 10 (1), 11 (9), 12 (10); pelvic-n rays I +5 (20); caudal-n rays ii+6+6+ii (2),
ii +6+7+ii (18). Branchiostegal rays 7 (19), 8 (1). Precaudal vertebrae 15 (2), 16 (2);
total vertebrae 38 (1), 39 (3), 40 (1). One specimen with 38 total vertebrae listed by
Johnson & Cohen (1974).
Lateral line complete, total pores 39 (1), 40 (1), 41 (2), 42 (5), 43 (6), 44 (4). Pores
in temporal canal 2 (17); supratemporal canal 3 (14); otic canal 1 (9), 2 (5); supraor-
bital canal 4 (1), 5 (11); epiphyseal branch 2 (9); infraorbital canal 10 (9), 11 (10);
preopercular canal 5(1), 6 (19); mandibular canal 6 (18), 7 (1).
Dentition
Teeth present on premaxilla, dentary, palatine, upper pharyngobranchial and fth
ceratobranchial. Dentigerous areas of premaxilla and dentary illustrated in Fig. 4(a).
Premaxillary teeth 75 (1), 80 (1), 81 (1), 84 (1), 90 (1), 95 (1), 99 (1), 100 (1), 101
(1), 102 (1), 104 (1), 106 (1), 107 (1), 109 (1), 117 (1), arranged in two to ve rows.
Dentary teeth 76 (1), 77 (1), 84 (1), 90 (1), 92 (1), 96 (2), 101 (1), 102 (1), 103 (2),
105 (1), 108 (1), 109 (1), 126 (1), arranged in two to ve rows; palatine teeth 5 (1), 6
(1), 8 (4), 9 (3), 10 (2), 11 (2), 12 (2), 13 (1), 14 (1), 16 (1), arranged in single row;
vomerine teeth absent (20). Gill rakers tooth-like, present on gill arches individually
or in groups of two or three rakers. Rakers on rst basibranchial 0 (10), 1 (1), 2 (1), 3
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

REVIEW OF DYSALOTUS 11
(1), 4 (1); rakers on rst ceratobranchial 10 (1), 11 (1), 15 (2), 16 (1), 17 (4), 19 (3),
20 (1), 21 (2), 22 (2), 25 (2), 28 (1); rakers on rst epibranchial 6 (1), 8 (1), 11 (3), 12
(2), 13 (4), 14 (5), 16 (3), 17 (1).
Distribution
Dysalotus alcocki is widely distributed in the Atlantic, Pacic and Indian Oceans,
more frequently in low latitudes (Fig. 1). In the Atlantic Ocean, it is more frequently
found throughout the South Atlantic and the western North Atlantic Ocean, including
the Gulf of Mexico and Caribbean Sea (40∘Nto21
∘30′S; 78∘Wto11
∘W). In the
eastern Pacic Ocean, it is known from southern Japan to northern Australia and the
central Pacic Ocean, from Hawaii to the central Pacic Plate (26∘Nto9
∘30′S; 14∘
40′Eto12
∘W). It is also known from the eastern Indian Ocean, from off India and
Indonesia (10∘Nto10
∘S; 92∘30′Eto114
∘E). Notably, it was never recorded from
the eastern Pacic Ocean, western Indian Ocean and most part of the western North
Atlantic Ocean.
Bathymetric distribution
Meso to bathypelagic, from depths of 746 to 3129 m.
DYSALOTUS OLIGOSCOLUS JOHNSON & COHEN 1974 [FIGS 2(C)
AND 3(B)–(D), AND TABLE 1]
Dysalotus oligoscolus Johnson & Cohen 1974: 32–34, gures 9A and 11 and table 2
(original description; type locality: eastern North Pacic Ocean, abyssal plain off Patten
Escarpment, off Baja California, California, U.S.A., 31∘06′N; 119∘24′W, c. 2600 m;
holotype: SIO 70-21-60). Johnson & Keene, 1990: 901 (checklist of shes from east-
ern North Atlantic Ocean). Fricke, 1999: 462 (checklist of shes from the Mascarene
Islands, Indian Ocean; expected record). McEachran & Sutton, 2003: 142–143 (check-
list of shes from western central Atlantic Ocean). Mundy, 2005 (checklist of shes
from Hawaii; expected record). Ban & Fukui, 2012 (rst record from Japan).
Material examined
Atlantic Ocean: BMNH 2002.3.2.86 (1, 55·9mm LS), western North Atlantic,
Azores–Britain Province, 48∘53′52′′ N; 16∘45′52′′ W, 4835 m, 7 October 2000,
R.R.S. Discovery; BMNH 1930.1.12.1063 (1, 123·4mm LS), central South Atlantic,
sub Antarctic, 38∘20′S; 22∘18′W, 1800 m, 10 June 1927, R.R.S. Discovery; USMN
207607 (1, paratype, 207·0mm LS), South Atlantic subtropical, north of Saint Helena
Island, 15∘45′S; 6∘06′W, 0 –1900 m, 5 April 1971, R.V. Walther Herwig; ZMH 24975
(former ISH 1459/71, 1, paratype, 117·0mm LS), eastern South Atlantic Ocean, Sub-
tropical, 33∘00′S; 7∘50′E, 0–2000 m, R.V. Walter Herwig; ZMH 24977 (former ISH
878/71, 2, paratypes, 147·2–220·3mmLS), South Atlantic subtropical, 39∘55′S; 26∘
02′W, 0 – 2000 m, R.V. Walter Herwig; ZMH 24978 (former ISH 960/71, 1, paratype,
135·7mmLS), South Atlantic Ocean subtropical, 39∘45′S; 17∘40′W, 0 –2000 m, R.V.
Walter Herwig; ZMH 122931 (former ISH 782-1986, 1, 204·2mmLS), North Atlantic,
52∘56′N; 16∘18′W, 9 July 1986; ZMH 114764 (former ISH 629-1976, 1, 170·0mm
LS), South Atlantic Ocean, 39∘08′S; 39∘59·8′W, 8 January 1976; ZMH 114824
(former ISH 511-1976, 1, 155·3mm LS), South Atlantic Ocean, 46∘27′S; 39∘53′W,
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

12 M. R. S. MELO
6 January 1976; ZMH 117487 (former ISH 5103-1979, 1, 111·4mm LS), North
Atlantic Ocean, 32∘59′N; 39∘41′W, 27 April 1979; ZMH 121750 (former ISH
155-1983, 1, 254·6mmLS), North Atlantic Ocean, 46∘05′N; 16∘49′W, 12 June 1983;
ZMH 121269 (former ISH 197-1982, 1, 201·6mmLS), central Atlantic Ocean, 45∘02′
N; 16∘07′W, 6 June 1982; ZMH 121147 (former ISH 896-1982, 1, 236·5mmLS), cen-
tral Atlantic Ocean, 45∘40′N; 27∘48′W, 11 June 1982. Indian Ocean: USMN 207612
(1, paratype, 81·6mm LS), western Indian Ocean, 4∘52′S; 60∘02′E, 0 –2030 m, 23
August 1963, R.V. Anton Bruun. Pacic Ocean: AMS 19608022 (1, 52·6mm LS),
western South Pacic Ocean, off New South Wales, Australia, 34∘05′S; 151∘56′E,
2412–2923 m, 23 March 1971; CBM-ZF 6170 (1, 62·6mmLS), western North Pacic
Ocean, off Boso Peninsula, Japan, 35∘01′23′′ N 141∘00′00′′ E, 7 July 1993; CBM-ZF
6175 (1, 63·5mmLS), western North Pacic Ocean, off Boso Peninsula, Japan, 35∘00′
N; 141∘00′E, 9 July 1993; LACM 9708 (1, paratype, 127·5mm LS), western Pacic
Ocean, Vicinty of Cedros Island, off Mexico, 27∘31′N; 115∘51′W, 25 January 1967,
R.V. Velero IV; USNM 288987 (1, 49·6mm LS), central Pacic Plate, 9∘50′N; 150∘
00′W, 0 – 1500, 8 February 1979, R.V. Gyre; NSMT-P 94638 (1, 63·6mm LS), North
Pacic Plate, 26∘10′40′′ N; 125∘50′42′′ E, 2147 m, 27 April 2002, R.V. Tansei-Maru;
SIO 51-87-60 (1, paratype, 150·4mm LS), eastern Pacic Ocean, off Baja California,
Mexico, 25∘30′N; 115∘16′W, 1902 m, 21 March 1951, R.V. Paolina-T; SIO 56-72-60
(1, paratypes, 99·1mm LS), eastern Pacic Ocean, off Baja California, Mexico, 27∘
07′N; 117∘02′W, 0 – 2926 m, 29–30 November 1951, R.V. Horizon; SIO 59-200-60
(1, paratype, 115·9mm LS), eastern Pacic Ocean, Farallon Basin, Gulf of California,
25∘15′N; 109∘50′W, 1261 m, 14 March 1959, R.V. Horizon; SIO 60-239-60 (1,
paratype, 66·3mm LS), central Pacic Ocean, Pacic Plate, 5∘12′N; 143∘07′W,
0– 2500 m, 6 July 1960, R.V. Spencer F Baird; SIO 60-247-60 (1, paratype, 241·2mm
LS), central North Pacic Plate, off Hawaii, 14∘52′N; 151∘31′W, 0–2100 m, 11 July
1960, R.V. Spencer F Baird; SIO 70-21-60 (holotype, 130·0mm LS), eastern North
Pacic Ocean, abyssal plain off Patten Escarpment, off Baja California, California,
U.S.A., 31∘06′N; 119∘24′W, c. 2600 m, R.V. Melville Station MV 69-VI-8, 8
June, 1969; ZMUC P. 6581 (former ZMUC DANA 3677, 1, paratype, 88·8mm LS),
Indo-Pacic Ocean, Banda Sea, Indonesia, 5∘28′S; 130∘39′E, 23 March 1929, R.V.
Dana; ZMUC P. 6582 (former ZMUC GALATHEA 607, 1, paratype, 60·0mm LS),
western South Pacic Ocean, west off South Island, New Zealand, 44∘18′S; 166∘
46′E, 17 January 1952, R.V. Galathea; ZMUC P. 6583 (former ZMUC GALATHEA
607, 1, paratype, 91·0mm LS), collected with ZMUC P. 6582.
Diagnosis
Dysalotus oligoscolus is distinguished from its congeners by having one to three
vomerine teeth present (v. vomerine teeth absent); and emergent prickles in two single
rows, dorsal and ventral to lateral line (v. emergent prickles irregularly arranged in
three to ve rows, dorsal and ventral to lateral line).
Description
Largest specimen examined 241·2mm LS. Morphometric data summarized in
Table I. General body shape as described for genus. Prickles present on posterior half
of body and caudal peduncle, in one to two dorsal and ventral rows to lateral line
[Fig. 3(b)–(d)].
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

REVIEW OF DYSALOTUS 13
First dorsal-n rays VIII (1), IX (2), X (6), XI (2); second dorsal-n rays 23 (1), 25
(1), 26 (4), 27 (4), 29 (1); anal-n rays 23 (1), 25 (1), 26 (3), 27 (6); pectoral-n rays 11
(6), 12 (5); pelvic-n rays I +5 (11); caudal-n rays ii +6+7+ii (10), ii +6+8+ii
(1). Branchiostegal rays 7 (11). Precaudal vertebrae 16 (3); total vertebrae 39 (3).
Lateral line complete, total pores 41 (2), 42 (2), 43 (5). Pores in temporal canal 1 (1),
2 (4); supratemporal canal 3 (4); otic canal 1 (2), supraorbital canal 5 (1); infraorbital
canal 11 (10); preopercular canal 6 (11); mandibular canal 6 (10), 7 (1); fth pore of
mandibular canal single (3).
Dentition
Teeth present on premaxilla, dentary, palatine, upper pharyngobranchial and fth cer-
atobranchial. Premaxillary teeth 60 (1), 89 (1), 104 (1), 138 (1), 139 (1), arranged in
two to ve rows; dentary teeth 67 (1), 87 (1), 119 (1), 132 (1), 136 (1), arranged in
two to ve rows; palatine teeth 6 (1), 8 (1), 9 (1), 13 (1), 14 (2), 16 (1), 17 (1), 19 (1),
22 (1), arranged in single row; vomerine teeth 1 (1), 2 (4), 3 (2), in small patches. Gill
rakers tooth-like, present on gill arches individually or in groups of two or three rakers.
Rakers on rst basibranchial absent (11); rakers on rst ceratobranchial 8 (1), 11 (1),
15 (1), 16 (1), 18 (1), 23 (1), 24 (1), 25 (1), 26 (2), 27 (1); rakers on rst epibranchial
3 (1), 7 (1), 8 (1), 11 (1), 12 (3), 13 (2), 16 (2).
Distribution
Dysalotus oligoscolus is distributed in the Atlantic, Pacic and Indian Oceans, more
frequently in high latitudes (Fig. 1). In the Atlantic Ocean, it is known from the central
South Atlantic (0∘to 40∘S; 33∘Wto26
∘W), and from the eastern North Atlantic (c.
49∘N; 16∘45′W). It is widespread in the Pacic Ocean, from Japan to New Zealand
in the west; Central Pacic Plate and in the eastern Pacic Ocean is known from off
California and Mexico (31∘Nto44
∘40′S; 130∘40′Eto110
∘W). It is also known
from eastern Indian Ocean (c.5
∘S; 60∘E).
Bathymetric distribution
Bathypelagic, from depths of 1500 to 4835 m.
Remarks
As previously noticed by Johnson & Cohen (1974: 34), most specimens of D.
oligoscolus have exclusively the emergent prickles; however, non-emergent prickles
are present in few specimens (e.g. USNM 207607 and 207612) making identication
confusing if based exclusively on this characteristic. The non-emergent prickles
can be observed in X-rayed or cleared-and-stained specimens and upon dissection
[Fig. 3(b)–(d)].
DYSALOTUS POULIULII, NEW SPECIES
urn:lsid:zoobank.org:act:EC0FA0E6-B738-4C73-9ED8-
9476AE5CB6A9
[FIGS 2(D), (E), 3(E) AND 4(B), AND TABLE I]
Holotype
FMNH 88135 (160·7mm LS), central North Pacic Ocean, off O′ahu, Hawaii,
U.S.A., 21∘23′N; 158∘18′W, 1500 m, 20 February 1971, R. E. Young collector.
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

14 M. R. S. MELO
Paratype
HUMZ 130474 (1, 157·1mm LS) central North Pacic Ocean, off the French Frigate
Shoals, Hawaii, U.S.A., 24∘53·3′N; 165∘38·8′W, 8 February 1994, midwater trawl,
T/V Hokusei-maru.
Diagnosis
Dysalotus pouliulii is distinguished from its congeners by the following character-
istics: premaxillary teeth 151–198 (v. premaxillary teeth 75– 117 in D.alcocki and
60–138 in D.oligoscolus); dentary teeth 136– 199 (v. dentary teeth 76 – 126 in D.
alcocki and 67– 132 in D.oligoscolus); upper jaw 51·9–54·9% in LH(v.57·2–69·2%
in D.alcocki and 64·4–74·4% in D.oligoscolus); and lower jaw 64·8–67·4% in LH(v.
72·3–81·4% in D.alcocki and 73·4–88·1% in D.oligoscolus).
Dysalotus pouliulii is further distinguished from D.oligoscolus by the presence emer-
gent prickles irregularly arranged in three to ve rows, dorsal and ventral to lateral line
(v. emergent prickles arranged in a single row dorsal to lateral line and a single row
ventral to lateral line); and vomerine teeth absent (v. vomerine teeth one to three).
Description
Largest specimen examined 160·7mmLS. Morphometric data summarized in Table I.
General body shape as described for genus. Emergent prickles present on posterior half
of body and caudal peduncle, irregularly distributed in three to four rows dorsal and
ventral to lateral line.
First dorsal-n rays X (2); second dorsal-n rays 26 (2); anal-n rays 26 (2);
pectoral-n rays 11 (1), 13 (1); pelvic-n rays I +5 (2); caudal-n rays ii +6+6+ii
(2). Branchiostegal rays 7 (2). Precaudal vertebrae 14 (1), total vertebrae 39 (1).
Lateral line complete, total pores 41 (2). Sensory system of head mostly destroyed
in holotype and paratype, data for temporal, supratemporal, otic, supraorbital canals
and fth pore of mandibular canal not available. Pores in infraorbital canal 10 (2);
preopercular canal 6 (2); mandibular canal 6 (2).
Dentition
Teeth present on premaxilla, dentary, palatine, upper pharyngobranchial and fth
ceratobranchial. Dentigerous areas of premaxilla and dentary illustrated in Fig. 4(b).
Premaxillary teeth 151 (1), 198 (1), arranged in two to seven rows; dentary teeth 136
(1), 199 (1), arranged in two to seven rows; palatine teeth 19 (1), 20 (1), arranged in
single row; vomerine teeth absent (1). Gill rakers tooth-like, present on gill arches indi-
vidually or in groups of two or three rakers. Rakers on rst basibranchial absent (2);
rakers on rst ceratobranchial 17 (1), 20 (1); rakers on rst epibranchial 13 (2).
Colour in alcohol
Only known specimens severely faded: body light brown to whitish; head and internal
area of mouth and gill arches bleached.
Distribution
Dysalotus pouliulii is only known from the two specimens collected next to the
Hawaiian Ridge, Hawaii, off O′ahu and off the French Frigate Shoals, in the central
North Pacic Ocean (Fig. 1).
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

REVIEW OF DYSALOTUS 15
Bathymetric distribution
Bathypelagic, known only from 1500 m.
Etymology
The specic name, pouliulii, is a patronym that honours Põuliuli. In accordance to
the Hawaiian Creation chant Kumulipo, Põuliuli and his wife Põwehiwehi generate
several species of shes, other marine animals such as crabs, seals, sea slugs, octopus,
porpoise, sharks, rays, walrus, whales and the forest growth on land. The word uliuli
is also applied to the colour of the deep ocean in comparison with the lighter shade of
shallower waters near shore, hence deep-profound-darkness (Beckwith, 1951).
KEY TO THE SPECIES OF DYSALOTUS
1a Vomerine teeth one to three; a single row of emergent prickles above and
below the posterior half of lateral line (non-emergent prickles may be present)
......................................................... Dysalotus oligoscolus
1b Vomerine teeth absent; three to ve rows of emergent prickles above and below the
posterior half of lateral line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2a Premaxillary teeth 75–117; dentary teeth 76– 126; upper jaw 57·2–69·2% in head
length; lower jaw 72·3–81·4% in head length . . . . . . . . . . . . . . . . . Dysalotus alcocki
2b Premaxillary teeth 151–198, dentary teeth 136 –199; upper jaw 51·9–54·9% in head
length; lower jaw 64·8–67·4% in head length. . . . Dysalotus pouliulii, new species
DISCUSSION
The genus Dysalotus includes some of the rarer species of chiasmodontids. Dysa-
lotus oligoscolus is the most distinctive species, with only a single row of emergent
prickles above and below the lateral line and vomerine teeth present; those are unique
characteristics among all chiasmodontids. Dysalotus alcocki and D.pouliulii are sim-
ilar species which can only be separated by the number of teeth and by the shorter
premaxilla and dentary in the former species.
Dysalotus and Kali are the two bathypelagic genera of the family Chiasmodontidae,
which also includes the mesopelagic genera Chiasmodon and Pseudoscopelus (Melo,
2008, 2009, 2010). The three species of Dysalotus are more frequently found at depths
from 1000 to 2500 m. Juveniles of D.alcocki (>40·0mm LS) are usually found from
750 m to about 1000 m (MCZ 60722, 65494, 163223 and 60809; UF 216141); juveniles
of the other species are not known. Only two specimens of D.alcocki were collected
shallower than 200 m (ZSI 1053/1, UF 106427), indicating that the genus very rarely
goes to shallower depths and is not likely undergo diel vertical migration. Very few
records exist for Dysalotus from below 2500 m (e.g. AMS 19608022, UF 216529, SIO
56-72-60 and SIO 59-200-60) and the deepest record is 4835 m (BMNH 2002.3.2·86),
suggesting that Dysalotus very rarely occurs at extreme depths or that those specimens
were accidental caught during deployment or recovery of an open net.
The distribution of species of Dysalotus is similar to those of Kali, with the exception
of the presence of Kali indica Lloyd 1909 in the Southern Ocean and Bering Sea where
no species of Dysalotus has ever been collected (Yabe & Cohen, 1981; Melo, 2008).
Moreover, while the species of Pseudoscopelus and Chiasmodon can be separated into
© 2016 The Fisheries Society of the British Isles, Journal of Fish Biology 2017, doi:10.1111/jfb.13194

16 M. R. S. MELO
groups with disjunct distributions, species of Dysalotus and Kali have wide ranges
and may occur sympatrically. The possible exception is D.pouliulii, which is known
from a single locality. Dysalotus alcocki is more often found at lower latitudes, while
D.oligoscolus occur at higher latitudes. The presence of D.alcocki in the Caribbean
Sea and Gulf of Mexico and D.oligoscolus in the Gulf of California is noteworthy. In
general, chiasmodontids are absent from semi-enclosed seas and bays.
For loans and specimens, thanks to M. McGrouther and J. Paxton (AMS); P. Campbell, C.
McCarthy and O. Crimmen (BMNH); M. Miya (CBM-ZF); D. Catania and T. Iwamoto (CAS);
L. Smith, M. Westneat and M. A. Rogers (FMNH); H. Wilkens (ISH); R. Rosenblatt, P. Hastings,
H. J. Walker Jr. and C. Klepadlo (SIO); R. Feeney, J. Seigel and C. Thacker (LACM); K. Hartel
and A. Williston (MCZ); H. Imamura (HUMZ); P. Buckup, M. Britto and G. Nunan (MNRJ);
K. Matsuura, M. Nakae and G. Shinohara (NSMT); L. Page and R. Robins (UF); J. Clayton,
G. D. Johnson, K. Murphy, S. Raredon and J. Williams (USNM); I. Eidus and R. Thiel (ZMH);
P. Møller and T. Menne (ZMUC). I am deeply indebted to J. Armbruster (Auburn University
Museum) for his support during the development of this study; P. Chakrabarty (LSU), C. Kenaley
(Boston College) and M. Okamoto (Seikai National Fisheries Research Institute) for comments
and suggestions on this manuscript; S. Ferdous (Auburn University Museum) for examining the
holotype of D.alcocki at the ZSI, R. Robins (UF), K. Swagel (FMNH), G. Shinohara (NSMT-P)
and K. Ban and A. Fukui (Tokai University) for data, photographs and X-rays of specimens. This
research was partially developed at the Department of Biological Sciences, Auburn University
and Museu de Zoologia Universidade de São Paulo; and received nancial support from CAPES
(process BEX 2030/03–9), FAPESP (processes 2010/50322-6, 2013/07818-9, 2014/15168-7),
Leonard P. Schultz Fund of the Division of Fishes (USNM) and Ernst Mayr Travel Grants in
Animal Systematics (Harvard University).
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