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Tetronarce cowleyi, sp. nov., a new species of electric ray from southern Africa (Chondrichthyes: Torpediniformes: Torpedinidae)

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A new species of torpedo ray, Tetronarce cowleyi, sp. nov., is described from specimens collected from the southeastern Atlantic Ocean. The new species is placed in the genus Tetronarce based on a uniform dorsal coloration and absence of papillae around the spiracles. The new species is distinguished from its closest congeners, the North Atlantic Tetronarce nobiliana Bonnaparte, 1835, and southwestern Atlantic Tetronarce puelcha Lahille, 1926, by a combination of morphological characteristics including a shorter spiracular length, a proportionally greater head length as measured between snout margin and fifth gill openings, a proportionally greater preoral snout length, a uniform shiny black or dark gray dorsal surface, lacking any prominent markings, and a creamy white ventral color with dark edges in juveniles but fading with growth. Teteronarce cowleyi, sp. nov., is further distinguished from T. nobiliana by its more circular anterior disc shape (vs. relatively straight in T. nobiliana), fewer tooth rows (32/28 vs. 38–53/38–52 in T. nobiliana), greater mouth width (1.5–1.7 times as great as interorbital width vs. 0.5–0.6 times interorbital width in T. nobiliana), smaller distance between second dorsal and caudal fins (3.5–4.9% vs. 6.6–6.8% in T. nobiliana), and a clasper length extending nearly to lower caudal fin origin (claspers in T. nobiliana that extend only two-thirds distance between second dorsal and caudal fins). Teteronarce cowleyi, sp. nov., is known from Walvis Bay, Namibia to Algoa Bay, Eastern Cape, South Africa, at depths of 110 to 457 m.
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Accepted by J. Sparks: 18 Feb. 2015; published: 19 Mar. 2015
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Tetronarce cowleyi, sp. nov., a new species of electric ray from southern Africa
(Chondrichthyes: Torpediniformes: Torpedinidae)
DAVID A. EBERT
1,2,3,6
, DIANE L. HAAS
1,4
& MARCELO R. DE CARVALHO
5
1
Pacific Shark Research Center, Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA. E-
mail: debert@mlml.calstate.edu
2
Research Associate, Department of Ichthyology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA
94118, USA
3
Research Associate, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown, 6140, South Africa
4
California Department of Fish and Wildlife, 830 S St., Sacramento, CA 95811, USA
5
Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Trav. 14, no. 101, São Paulo, SP,
CEP 05508-090, Brazil. E-mail: mrcarvalho@ib.usp.br
6
Corresponding author
Abstract
A new species of torpedo ray, Tetronarce cowleyi, sp. nov., is described from specimens collected from the southeastern
Atlantic Ocean. The new species is placed in the genus Tetronarce based on a uniform dorsal coloration and absence of
papillae around the spiracles. The new species is distinguished from its closest congeners, the North Atlantic Tetronarce
nobiliana Bonnaparte, 1835, and southwestern Atlantic Tetronarce puelcha Lahille, 1926, by a combination of morpho-
logical characteristics including a shorter spiracular length, a proportionally greater head length as measured between
snout margin and fifth gill openings, a proportionally greater preoral snout length, a uniform shiny black or dark gray dor-
sal surface, lacking any prominent markings, and a creamy white ventral color with dark edges in juveniles but fading with
growth. Teteronarce cowleyi, sp. nov., is further distinguished from T. nobiliana by its more circular anterior disc shape
(vs. relatively straight in T. nobiliana), fewer tooth rows (32/28 vs. 38–53/38–52 in T. nobiliana), greater mouth width
(1.5–1.7 times as great as interorbital width vs. 0.5–0.6 times interorbital width in T. nobiliana), smaller distance between
second dorsal and caudal fins (3.5–4.9% vs. 6.6–6.8% in T. nobiliana), and a clasper length extending nearly to lower cau-
dal fin origin (claspers in T. nobiliana that extend only two-thirds distance between second dorsal and caudal fins). Teter-
onarce cowleyi, sp. nov., is known from Walvis Bay, Namibia to Algoa Bay, Eastern Cape, South Africa, at depths of 110
to 457 m.
Key words: Tetronarce, electric ray, new species, Namibia, South Africa, Southeastern Atlantic Ocean
Introduction
The family Torpedinidae Bonaparte, 1838, has long been considered to consist of a single genus, Torpedo
Houttuyn, 1764, and two subgenera, Tetronarce Gill, 1862, and Torpedo Houttuyn, 1764 (Compagno, 2005).
However, these two subgenera have been recently elevated to full generic rank based on their distinct morphology
(treated as distinct genera in Carvalho et al., 2002; Ebert et al., 2013; Ebert, 2014; Carvalho, in press). The two
genera can be distinguished by their dorsal coloration and the presence or absence of spiracular papillae.
Furthermore, Tetronarce species tend to attain a much larger size (up to 180 cm total length; TL) than Torp edo
species, which are usually small to moderate sized (range from 25 to 80 cm TL) electric rays (Carvalho, in press).
The genus Tetronarce has up to 10 valid species, while the genus Torpedo has at least 15 valid species; both genera
have several known undescribed species (Carvalho et al., 2002; Compagno, 2005; Haas & Ebert, 2006; Carvalho,
in press).
Representatives of both genera occur in southern African waters. The genus Torp edo is represented by T.
fuscomaculata Peters, 1855, and T. sinuspersici Olfers, 1831 (Compagno, 1986; Compagno et al., 1989; Carvalho,
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in press) and the genus Tetronarce by a single species, referred to as T. nobiliana (Bonaparte, 1835), a common
North Atlantic and Mediterranean species that is reported to occur in southern African waters (Compagno et al.,
1989). The occurrence of a Tetronarce species was first reported by Thompson (1914) as Torpedo hebetans Lowe,
1841, but was subsequently re-identified without comment as Narcobatus nobiliana by Barnard (1925). Most
authors have since accepted this species as T. nobiliana (see synonymy below). However, the taxonomic status of
North Atlantic and Mediterranean T. nobiliana and southern African T. cf. nobiliana has never been clearly
documented. Compagno (1999) and Carvalho et al. (2002) both considered the southern African T. cf. nobiliana to
possibly represent an undescribed species. Here we describe a new species of Tetronarce from southern Africa;
comparisons with the morphologically similar southwestern Atlantic species Teteronarce puelcha (Lahille, 1926)
are also provided.
FIGURE 1. Measurements taken on Tetronarce cowleyi from dorsal (A), ventral (B), lateral tail (C), dorsal head (D), and
ventral head (E) regions. Abbreviations are listed in Table 1.
Material and methods
Measurements and terminology are modified from Carvalho (1999) and Carvalho et al. (2002). A total of 56
measurements were taken in a straight line to the nearest 0.1 mm, and are presented as proportions of total length
(TL) to facilitate direct comparisons (Fig. 1). Pseudobranchial folds, tooth rows, and spiral-valve turn counts were
also taken. Morphometrics for the holotype and a single paratype (in parenthesis below) were compared with three
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syntypes of T. nobiliana and additional material from the North Atlantic and Mediterranean, as well as T. puelcha
from the southwestern Atlantic. Type specimens are deposited in the South African Institute of Aquatic
Biodiversity (SAIAB). Institutional abbreviations for comparative material are: American Museum of Natural
History, New York (AMNH); Academy of Natural Sciences of Drexel University, Philadelphia (ANSP); California
Academy of Sciences (CAS); Moss Landing Marine Laboratories (MLML); Museum of Comparative Zoology
(MCZ) of Harvard University; Muséum national d'Histoire naturelle, Paris (MNHN); Museu de Zoologia da
Universidade de São Paulo (MZUSP); Núcleo de Pesquisas em Chondrichthyes, Santos (NUPEC); and
Departamento de Zoologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro (UERJ).
Tetronarce cowleyi,
sp. nov.
Cowley’s torpedo ray
(Figures 2–6, Table 1)
Torpedo nobiliana: Fowler, 1936, p. 121, fig. 50; Fowler, 1941, p. 346; Smith, 1949, p. 75, fig. 92; Smith, 1965, 75, fig. 92;
Allué et al., 1984, p. 125; Compagno, 1986, p. 112, fig. 23.2; Lloris, 1986, p. 129, fig. 44; Turon et al., 1986, p. 69;
Compagno et al., 1989, p. 80, ill.; Compagno et al., 1991, p. 89.
Narcobatus nobilianus: Barnard, 1925, p. 89; Norman, 1935, p. 37; Barnard, 1947, p. 30, pl. 4, fig. 10.
Torpedo hebetans: Thompson, 1914, p. 159; Von Bonde & Swart, 1923, p. 15.
Holotype. SAIAB 25190, mature male, 626 mm TL, SE Atlantic Ocean, off the west coast of South Africa, 33
o
39.0’S, 17
o
34.0’E, 262 m, 20 January 1985, F.R.S. Africana survey cruise 028, station A2316, haul 062, by 60 m
German bottom trawl.
Paratype. SAIAB 25347, immature female, 270 mm TL, SE Atlantic Ocean, off the west coast of South
Africa, 35
o
59.0’S, 19
o
58.5’E, 175 m, 6 July 1985, F.R.S. Africana survey cruise 033, station A2768, haul 024, by
60 m German bottom trawl.
Diagnosis. A medium-sized Tetronarce species, with a uniform shiny black to dark gray live dorsal color,
distinguished from its most similar congeners T. nobiliana and T. puelcha by the following combination of
characters: shorter spiracular length (1.5–1.6% TL in T. cowleyi as compared to 2.6–2.8% in T. nobiliana and
2.4–3.1% in T. puelcha), a proportionally greater head length as measured between snout margin and fifth gill
openings (30.5–31.2% TL in T. cowleyi vs. 24.7–25.8% in T. nobiliana and 26.8% in adult male T. puelcha), and a
proportionally greater preoral snout length (8.9–9.3% TL compared to 7.4–7.6% in T. nobiliana and 6.5–8.4% in T.
puelcha). Teteronarce cowleyi, n. sp., is further distinguished from T. nobiliana by its more circular anterior disc
shape (vs. relatively straight), fewer tooth rows (32/28 in 626 mm TL adult male holotype vs. 38/38 in a 655 mm
TL adult male T. nobiliana from the North Sea, and up to 53/52 in 555–740 mm TL adult T. nobiliana males from
the Mediterranean), greater mouth width (1.5–1.7 times as great as interorbital width vs. 0.5–0.6 times interorbital
width in T. nobiliana), smaller distance between second dorsal and caudal fins (3.5–4.9% vs. 6.6–6.8% in T.
nobiliana), and greater clasper length (in mature T. cowleyi claspers extend nearly to lower caudal fin origin, while
in T. nobiliana clasper extends only two-thirds the distance between second dorsal and caudal fins).
Description. Disc broadly rounded, anterior margin nearly straight in outline with a slight median
protuberance. Disc width greater than length; disc width 65.2% TL in holotype (69.3% in paratype) and disc length
55.4% (58.9%) TL. Disc widest at about one-third its length, and thickest at anterior margin. Disc does not overlap
origin of pelvic fins, with prominent free posterior lobes broadly rounded. Disc fleshy, thick anteriorly,
progressively thinning posteriorly. Preorbital snout length about 7.0–7.9 times in disc length, 1.8–2.3 times orbit
diameter, and slightly greater than prenasal snout length. Eyes small, orbital diameter about 2.1–2.7 times spiracle
length. Eyes and spiracles close together, space between them about equal to interspiracular width. Distance
between orbits 1.2–1.5 times distance between spiracles. Spiracles smooth, lacking papillae, moderately large and
hemispherical, opening posteriorly. Pseudobranchial folds line anterior margin inside spiracles; pseudobranchial
fold number differs between left and right, 13–12 (10–9). Electric organs not clearly visible dorsally, but
distinguishable in ventral view, especially in paratype. Electric organs originate very close to anterior disc margin,
anterior to eyes and nostrils, and terminate posteriorly, just past fifth gill slits. Electric organs kidney shaped,
widest anteriorly between mouth and first gill slit. Length of electric organ about 2.0–2.5 times its greatest width.
Dorsal and ventral skin surfaces entirely smooth.
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FIGURE 2. Dorsal (A) and ventral (B) views of holotype of Tetronarce cowleyi, sp. nov. (SAIAB 25190, 626 mm TL, mature
male). Scale bar represents 5 cm.
Nasal curtain subquadrangular, its width about two to three times its length. Nasal curtain extends posteriorly
in a relatively straight line towards mouth. Posterior margin of nasal curtain with two confluent lobes, broadly
rounded and angled medially; margin not fringed. Posterior margin of nasal curtain with a slight median lobe.
Outer margins of nostrils situated at level of mouth corners; posterior contour of nostrils confluent with prominent
median lobes that contact nasal curtain at corners and separate nostrils from mouth. Skin at corners of mouth loose,
deeply furrowed. Mouth broadly arched with relatively large gape; width greater than internarial width; internarial
width about 1.6 times in mouth width. Teeth set in quincunx, flattened labial-lingually, morphologically similar in
both upper and lower jaws, with well-developed single cusps. Gill slits crescent shaped. First gill slits positioned at
about one-third of disc length, fifth gill slit situated slightly more than one-half disc length. First four gill slits
nearly equal in length, fifth gill length about one-half to two-thirds length of first four. Distance between first gill
slits slightly greater than distance between fifth gill slits. Length of first four gill slits nearly two times spiracle
length; fifth gill slit length nearly same as spiracle length.
Pelvic fins originate just anterior to disc insertion (pelvic fin description based on right fin; left fin rear tip
noticeably shorter due to prior injury). Pelvic fins long, length about one-fifth of total length and about two-thirds
of pelvic fin width. Anterior margins of pelvics relatively straight, but broadly rounded at apex; pelvic posterior
margins more convex. Pelvic fins widest at about one-half of their length. Pelvic fins much wider than long; length
about 62% of width. Cloaca situated anterior to one-fifth length from pelvic fin origin. Claspers of mature male
holotype, and in non-type adult males, extend well past insertion of second dorsal fin; claspers of immature non-
type specimens do not extend past free rear tips of pelvic fins; claspers of maturing males may extend past pelvic
fin tips, but generally do not reach second dorsal fin insertion. Claspers dorsoventrally flattened, clasper groove about
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80% length of inner clasper length, where it curves medially. Dorsal and ventral pseudosiphon slits present; ventral
pseudosiphon about one-third greater in length than dorsal pseudosiphon. A fleshy integumental flap covers hypopyle.
Tail moderately short and stout, 22.1% (23.4%) TL as measured from second dorsal fin insertion, but tail
length from cloaca 24.4% (20.4%) TL. Tail tapers from posterior tips of pelvic fins toward caudal fin. Tail width
about two times greater than height at pelvic tips, but more circular in cross-section at caudal fin origin. Lateral tail
folds ridgelike, originating below second dorsal fin origin, becoming more prominent along caudal peduncle
region, and terminating posterior to dorsal and ventral facets of caudal peduncle. Tail-fold origin not as
distinguishable as insertion. Lateral tail folds vary slightly in length between each side of tail in holotype and
paratypes, 12.5–13.3% (11.8–12.3%) TL.
First dorsal fin broad, subtriangular with rounded corners, and originating just posterior to level of widest
pelvic fin width. Anterior margin of first dorsal moderately slanted, with posterior free lobe about equal to two-
thirds the base length. First dorsal fin base length about two-thirds of its height. Less than half of first dorsal fin
base (about 40%) situated over pelvic fin bases, but posterior free lobe of first dorsal does not extend posterior to
level of pelvic fin tips (left pelvic fin free rear tip notably shorter due to prior injury). First dorsal fin posterior
margin ends well anterior to level of second dorsal fin origin in holotype, but posterior to origin in paratype. First
dorsal fin about one-third larger than second dorsal; first dorsal fin height about 1.5–1.6 times greater than second
dorsal height; first dorsal fin base length 1.5–1.9 times greater than second dorsal base length. Dorsal fins
somewhat similar in shape, second dorsal fin with lower and more acute apex. Interdorsal space about equidistant
between second dorsal fin insertion and dorsal caudal origin. Caudal fin emarginated, tall and triangular, overall
height 22.3% (25.5%) TL. Upper margin of caudal fin slightly longer, and more sloping, than lower margin.
Posterior margin of caudal fin slightly concave at about mid-height. Apices of caudal fin broadly rounded, more so
in female paratype. Tooth row counts in upper jaw 32 (26) and lower jaw 28 (26). Spiral valve counts 14 for
holotype and 16 for paratype.
FIGURE 3. Dorsal (A) and ventral (B) views of paratype of Tetronarce cowleyi, sp. nov. (SAIAB 25347, 270 mm TL,
immature female). Scale bar represents 5 cm.
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FIGURE 4. Dorsal head and ventral nasoral region of Tetronarce cowleyi, sp. nov. (holotype SAIAB 25190, 626 mm TL,
mature male).
Coloration. Dorsal surface color in life is a uniform shiny black or dark gray; ventral surface creamy white;
juveniles darker on disc and pelvic fin margins, but fading in adults. After preservation dorsal surface fades to a
brownish gray.
Etymology. The species is named after Paul Cowley, South African Institute for Aquatic Biodiversity, in
recognition of his contributions to the study of fishes in southern Africa.
Distribution. Tetronace cowleyi occurs around southern Africa, from Walvis Bay, Namibia to Algoa Bay,
Eastern Cape, South Africa (Compagno et al. 1991, as T. nobiliana).
Size. Maximum total length for females is 1133 mm and for males is 680 mm.
Biological notes. A benthopelagic species mostly found along the outer continental shelf and upper slope near
the bottom, but also well off it and at bottom depths of 110–457 m (Compagno et al., 1989). Females mature by at
least 1005 mm TL and males at about 582 mm TL. Smallest free-swimming neonate recorded measured 186 mm
TL. Neonates have been collected during pelagic plankton tows on the edge of the outer continental shelf southwest
of Cape Town (Compagno et al., 1991). It is suspected that the limited capture of this electric ray in bottom trawls
is not indicative of its abundance in the area, but rather its ability to move well off the bottom while foraging for
fish and other large prey. Diet consists mainly of large bottom and pelagic bony fishes and small sharks.
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FIGURE 5. Left clasper of Tetronarce cowleyi, sp. nov. (holotype SAIAB 25190, 626 mm TL, mature male). Abbreviations:
CG, clasper groove; DPS, dorsal pseudosiphon; IF, integumental flap; VPS, ventral pseudosiphon.
FIGURE 6. Lateral tail region of Tetronarce cowleyi, sp. nov. (holotype SAIAB 25190, 626 mm TL, mature male).
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TABLE 1. Morphometrics and meristics of the holotype and paratype of Tetronarce cowleyi, sp. nov., expressed as % of
total length (except TL and last two characters), with abbreviations as in Figure 1.
SAIAB 25190 SAIAB 25347
Mature male Immature female
Holotype Paratype
Total Length (TL) (mm) 626 270
Disc Width (DW) 65.2 69.3
Disc Length (DL) 55.4 58.9
Snout, Preorbital (POSL) 7.0 7.9
Snout, Preoral (PRSL) 9.3 8.9
Snout, Prenasal (PNSL) 6.9 7.1
Interorbital Width (IOW) 4.8 4.4
Orbital Diameter (OD) 3.1 4.3
Interspiracular Distance (ISD) 5.9 6.6
Spiracle Length (SPL) 1.5 1.6
Orbital–Spiracle Length (OSL) 5.3 6.7
Endolymphatic Interpore Width (IPW) 0.8 1.1
Snout–Endolymphatic Pore Length (SNPL) 16.8 18.4
Orbit–Endolymphatic Pore Length (OPL) 9.0 10.7
Dorsal 1 Height (D1H) 7.1 8.1
Dorsal 1 Base Length (D1L) 5.7 5.7
Dorsal 2 Height (D2H) 4.8 5.2
Dorsal 2 Base Length (D2L) 3.8 3.0
Interdorsal Space (IDS) 5.0 3.7
Dorsal 2 to Caudal Space (D2CS) 4.9 3.5
Caudal Overall Height (CH) 22.3 25.5
Caudal Height, Upper Lobe (UCLH) 10.1 11.7
Caudal Height, Lower Lobe (LCLH) 11.5 12.7
Caudal Length, Dorsal Margin (UCML) 18.8 21.1
Caudal Length, Ventral Margin (LCML) 16.7 17.3
Tail, Postdorsal Length (PDTL) 22.1 23.4
Tail, Height at Pelvic Tips (TPH) 4.0 3.6
Tail, Width at Pelvic Tips (TPW) 7.9 6.3
Tail, Height at Caudal Origin (TCH) 2.8 2.8
Tail, Width at Caudal Origin (TCW) 2.9 4.4
Lateral Tail Fold Length (LTFL) (left/right) 13.3/12.5 12.3/11.8
Head Length, Ventral (VHL) 31.2 30.5
Head Length, Dorsal (DHL) 17.3 19.0
Mouth Width (MW) 7.4 8.0
Internarial Width (INW) 4.6 5.0
Nasal Curtain Length (NCL) 1.6 1.8
Nasal Curtain Width (NCW) 4.4 4.2
Length, 1st Gill Slit (GSL1) 2.9 2.3
Length, 3rd Gill Slit (GSL3) 2.8 2.4
......continued on the next page
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Comparisons. Species of Tetronarce are very similar morphologically, impeding their quick and
straightforward identification. The genus has some 19 available nominal species, of which only eight may be valid
(Carvalho et al., 2002); a single nominal species has been described from southern Africa, Torpedo smithii
Günther, 1870, a junior synonym of Torpedo fuscomaculata Peters, 1855 (Compagno, 1986; Carvalho et al., 2002).
Morphometric characters must be employed with caution because specimens are soft and flabby and usually
preserved with skewed proportions of disc, tail and pelvic fins, among other features. Even though we present
below proportional morphometric parameters that distinguish T. cowleyi from western North Atlantic T. nobiliana
and southwestern Atlantic T. puelcha, we note that the validity of T. cowleyi is further supported by other
diagnostic features, and that the values reported were taken from well preserved material of all three species. Some
morphometric parameters, however, need to be further tested in greater series of well-preserved specimens.
Tetronarce is presently under review (Carvalho, Gomes & Séret, in prep.), and the lack of well preserved series is
the principal difficulty in uncovering characters consistent enough for global species identification.
Comparison of T. cowleyi to other Atlantic species of Tetronarce (primarily western North Atlantic T.
nobiliana and southwestern Atlantic T. puelcha) reveals a set of morphological and morphometric differences that
aid in distinguishing them (parameters for T. nobiliana below are based on the well preserved specimens MCZ
3604 and MLML uncat.; numerous additional specimens from the MCZ, AMNH and MNHN are not included; data
for T. puelcha is from Carvalho & Gomes, unpub.). Many of the differences below are minor and some are
continuous; these are provided to broaden comparisons and not necessarily to diagnose the new species (see
Diagnosis above). We also compared T. cowleyi to Mediterranean T. nobiliana based on material in the MNHN and
the redescription of Capapé & Desoutter (1980), who report on material from France and Tunisia. Specimens of the
other valid species of Tetronarce [T. californica (Ayers, 1855), T. fairchildi (Hutton, 1872), T. tokionis (Tanaka,
1908), ?T. macneilli (Whitley, 1932), T. tremens (de Buen, 1959, of which T. peruana [Chirichigno, 1963] is a
synonym), and T. formosa (Haas & Ebert, 2006)] have also been examined but are not compared in detail to T.
cowleyi below.
The anterior disc margin of T. cowleyi is curved, with the overall disc shape being more ovate than the
relatively straight-edged anterior margin and subcircular disc shape of western North Atlantic T. nobiliana (and to
TABLE 1. (Continued)
SAIAB 25190 SAIAB 25347
Mature male Immature female
Holotype Paratype
Length, 5th Gill Slit (GSL5) 1.2 1.6
Distance between 1st Gill Slits (GSS1) 17.2 20.7
Distance between 5th Gill Slits (GSS5) 15.9 17.4
Pelvic Fin Length (PFL) 19.0 17.4
Pelvic Fin Width (PFW) 30.8 28.0
Snout to Mid-cloaca (SCL) 59.3 61.5
Snout to Dorsal 1 Origin (SD1) 62.3 64.8
Snout to Dorsal 2 Origin (SD2) 73.2 73.7
Snout to Upper Caudal Origin (SUC) 82.1 81.1
Snout to Maximum Disc Width (SDW) 32.1 30.8
Mid-cloaca to Dorsal 1 Origin (CLD1) 3.5 3.0
Mid-cloaca to Dorsal 2 Origin (CLD2) 14.4 12.2
Mid-cloaca to Tail End (CLCF) 39.9 39.9
Electric Organ Length (EOL) 37.5 34.2
Electric Organ Greatest Width (EOW) 14.7 17.4
Electric Organ Width at 1st Gill Slit (EOWG) 13.1 12.7
Pseudobranchial Folds (left/right) 13/12 10/9
Tooth Rows (upper/lower) 32/28 26/26
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some extent of T. puelcha as well). The disc width of T. cowleyi at 65.8–69.3% of TL is slightly greater than T.
nobiliana at 61.8–63.8% but closer to T. puelcha at 65.1–72.7% (adult specimens). Other proportional differences
include a greater prenasal length at 6.9–7.1% vs. 5.8–6.6% (but overlapping with T. puelcha at 5.7–8.2%), a greater
orbit to endolymphatic pore length of 9.0–10.7% compared to 8.3–8.6% in T. nobiliana, and a much greater head
length to fifth gill openings at 30.5–31.2% compared to 24.7–25.8% in T. nobiliana. Spiracular length is shorter in
T. cowleyi at 1.5–1.6% as compared to T. nobiliana at 2.6–2.8% and to T. puelcha at 2.1–3.1%. The snout to
maximum disc width is slightly greater in T. cowleyi at 30.8–32.1% compared to T. nobiliana at 28.0–29.4%. The
electric organ length is proportionally greater in T. cowleyi at 34.2–37.5% vs. 26.4–31.9% in T. nobiliana.
Additional proportional differences between T. nobiliana and T. cowleyi include a first dorsal fin base that is
shorter in T. cowleyi at only 0.6–0.9 times second dorsal–caudal space, vs. 1.1–1.3 times in T. nobiliana (T. puelcha
at 0.7–0.9). The second dorsal fin base is shorter in T. cowleyi at 1.2–1.3 times second dorsal–caudal space, but
1.8–2.0 times in T. nobiliana and 1.6–2.1 in T. puelcha. Interdorsal space is 1.0–1.1 times second dorsal–caudal
space in T. cowleyi, while it is only 0.7 times in T. nobiliana and 0.5–0.7 in T. puelcha. Caudal peduncle height is
1.2–1.7 times second dorsal–caudal space in T. cowleyi, while in T. nobiliana this distance is greater at 2.1 times.
The midcloaca to first dorsal fin distance for T. cowleyi is shorter at 3.0–3.5% relative to T. nobiliana at 4.4%. The
pelvic fins in male T. cowleyi are similar in width (30.8%) and length (19.0%) to T. nobiliana at 27.0–31.8% and
19.8–21.6%, respectively (width 31.6% and length 14.6% in adult male T. puelcha). The caudal fin of T. cowleyi is
proportionally larger with a slightly greater overall caudal fin height of 22.3–25.5% (25.5% in adult male T.
puelcha) vs. 21.2–22.0% in T. nobiliana. Other caudal fin proportions include an upper caudal fin height of
10.1–11.7% vs. 9.0–9.6%, an upper caudal fin margin of 18.8–21.1% (21.3% in adult male T. puelcha) vs.
16.8–17.4%, and a lower caudal fin margin of 16.7–17.3% (18.7% in adult male T. puelcha) vs. 14.8–16.0%,
respectively. The lateral tail folds are shorter in T. cowleyi at 11.8–13.3% (similar to T. puelcha at 11.2–15%) vs.
16.4–16.7% for western North Atlantic T. nobiliana.
Tooth row counts may be informative for Tetronarce species when specimens of similar size are directly
compared. Tooth row counts for males and females are similar until reaching maturity (Carvalho, unpub.), but
larger adult females usually have more tooth rows and significantly greater size. Both specimens of T. cowleyi have
lower total tooth row counts compared to western North Atlantic, eastern North Atlantic and Mediterranean T.
nobiliana, and southwestern Atlantic T. puelcha: 32/28 in the adult male holotype (626 mm TL) and 26/26 in the
immature female paratype (270 mm TL) of T. cowleyi, vs. 48/46 in an adult male (835 mm TL) and 66/61 in an
adult female (Bigelow & Schroeder, 1953) from the western North Atlantic, 38/38 in an adult male (655 mm TL)
from the North Sea (Bigelow & Schroeder, 1953), up to 53/52 in adult males (from 555–740 mm TL) in
Mediterranean T. nobiliana (reported by Capapé & Desoutter, 1980; see also Tortonese, 1957; Bini, 1967); and 35/
37 in an adult male (670 mm TL), 34/32 in a subadult male (553 mm TL) and 23–25/23–25 in immature females
(257–307 mm TL) of T. puelcha.
Vertebral counts are not as informative as tooth row counts to separate Atlantic species of Tetronarce, as T.
nobiliana, T. cowleyi and T. puelcha are similar in numbers of trunk (monospondylous) and caudal
(diplospondylous) vertebrae (all Tetronarce species are relatively similar in vertebral numbers; Carvalho, unpub.).
The holotype of T. cowleyi has 33 trunk and 73 caudal (post-trunk) vertebrae (106 total vertebrae), while the
smaller female paratype has slightly fewer vertebrae, with 32 trunk and 71 caudal (103 total vertebrae). In
comparison, a female specimen of T. puelcha from southeastern Brazil that is much smaller (at 474 mm TL) than
the holotype of T. cowleyi (626 mm TL) has 101 total vertebrae, and a 553 mm TL subadult male speciumen has
104 total vertebrae (the largest specimen of T. puelcha counted). Lahille (1928) reported an even higher count in a
much larger specimen of T. puelcha (1040 mm TL) from Argentina (58 trunk, 74 caudal and 132 total vertebrae)
but he probably included synarcual foramina as indicative of anterior trunk vertebrae. Capapé & Desoutter (1980)
report for Mediterranean T. nobiliana vertebral counts similar to T. cowleyi (32–36 trunk and 98–103 total
vertebrae), but without specifying their sample size or from which specimens counts were taken (they examined
material from Tunisia and France). More specimens of all three species need to be examined for vertebral counts
and other meristic features.
The claspers of mature T. cowleyi appear to have several morphological and proportional differences from
those of T. nobiliana. Clasper length in mature T. cowleyi individuals extend nearly to lower caudal fin origin while
those of T. nobiliana are shorter, extending only two-thirds the distance between second dorsal and caudal fins
(confirmed in T. nobiliana from the western North Atlantic and Sénegal). The clasper groove in T. cowleyi is
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shorter, at 1.2 times the inner clasper length, than in T. nobiliana at 1.5 times the inner clasper length. The small
integumental flap on clasper distal extremity in T. cowleyi is lobate, while in T. nobiliana it is relatively straight.
Further comparisons are needed with more adult male specimens of T. nobiliana from different regions to
corroborate the relevance of these features.
Dorsal coloration in T. cowleyi is a uniform shiny black or dark gray with no prominent markings (Compagno
et al., 1989), while in T. nobiliana it is a dark chocolate to purplish brown above, either uniform or with a few
obscure darker spots (Bigelow & Schroeder, 1953), and in T. puelcha it is also a uniform purplish to brown,
sometimes with smaller darker blotches and irregular scratch-like marks (neonates with lighter margins on dorsal
and caudal fins). Ventral surface color for T. cowleyi is a uniform creamy white with juveniles having darker disc
and pelvic fin edges, but fading with growth. The ventral surface of T. nobiliana and T. puelcha is generally white,
but with dark edges along the disc and pelvic fins (Bigelow & Schroeder, 1953). Spiral valve counts for T. cowleyi
ranged from 14–16 while it is 12–13 for the North Atlantic T. nobiliana (Bigelow & Schroeder, 1953), and
generally 14 in T. puelcha (Carvalho & Gomes, unpub.).
Tetronarce cowleyi was also compared to syntypes of T. nobiliana (three measured), with the former species
having somewhat longer proportional measurements for snout length to disc width ratio (65.8–69.3% vs.
48.3–64.1%, respectively), preorbital length (7.0–7.9% vs.5.5–7.2%), preoral length (8.9–9.3% vs. 6.2–8.3%),
head length to fifth gill opening (30.5–31.2% vs. 24.2–29.1%), snout to maximum disc width (30.8–32.1% vs.
19.0–25.2%), and snout to upper caudal origin (81.1–82.1% vs. 74.8–80.4%). The third gill opening length fits
6.1–7.8 times into dorsal head length in T. cowleyi, a much shorter ratio than the 10.7–15.1 times observed in the T.
nobiliana syntypes. The snout to endolymphatic pore length is also somewhat longer in T. cowleyi at 16.8–18.4%
vs. 15.1–16.0% for T. nobiliana. The electric organ length is greater in T. cowleyi (43.2–37.5%) than in the T.
nobiliana syntypes (30.6–35.2%). The pelvic fin width is greater in T. cowleyi (28.0–30.8%) than in the T.
nobiliana syntypes (19.0–25.2%). The distance from mid-cloaca to first dorsal fin origin is shorter in T. cowleyi
than for T. nobiliana syntypes at 3.0–3.5% vs. 3.5–4.1%, respectively. The dorsal caudal space is about 1.1 times
into interdorsal space, a ratio slightly greater in T. cowleyi relative to this measurement in T. nobiliana syntypes at
0.6–0.9 times. Overall the caudal fin height of T. cowleyi is higher than in T. nobiliana syntypes (22.3–25.5% vs.
14.8–22.5%). Other caudal fin measurements reveal that the caudal fin is proportionally larger in upper caudal fin
height (10.1–11.7% vs. 7.3–9.3%), and lower caudal fin height (11.5–12.7% vs. 7.1–10.9%). However, all syntypes
of T. nobiliana (there are 15 in all) are poorly preserved, small juvenile specimens that do not have intact
proportions; the parameters given above based on three syntypes show some significant differences from T.
cowleyi, but illustrate the difficulty in carrying out comparisons among species of Tetronarce. Small specimens of
T. cowleyi need to be compared with the syntypes of T. nobiliana, even though discrepancies will also occur.
Comparison of biological parameters between T. cowleyi and North Atlantic T. nobiliana
shows that the latter
matures at a much larger size and obtains a greater maximum length. Maturity estimates for T. nobiliana from the
western North Atlantic show that females mature between 1250–1350 mm and attain a maximum length of at least
1517 mm TL (Sandra Downing, NOAA Fisheries, Northeast Marine Science Center, pers. comm.). Males mature
between 750–850 mm TL and reach a maximum length of at least 1112 mm TL (S. Downing, pers. comm.). By
comparison, T. cowleyi females mature by 1005 mm TL, while males mature at about 582 mm TL. The maximum
reported size for T. cowleyi is 1133 mm TL. These parameters in T. cowleyi are slightly closer to T. puelcha from
Brazil, for which sexual maturity in males is established at a slightly greater size between 623 and 670 mm TL, and
the maximum total length is 1202 mm TL (Carvalho & Gomes, unpub.). Mediterranean Sea T. nobiliana specimens
are reported to attain a maximum length of 1800 mm (Bigelow & Schroeder, 1953), but Capapé & Desoutter
(1980) report slightly smaller sizes for maturity in their examined specimens (smallest adult male 555 mm TL and
smallest adult female 900 mm TL).
The phylogenetic relationships and identification of chondrichthyans have recently been explored using the
molecular marker NADH2, which has been shown to reliably distinguish closely related species in many genera
(Naylor et al., 2012). DNA sequence analysis using NADH2 by Naylor et al. (2012) found that the average
pairwise difference among eight western North Atlantic T. nobiliana was 1.7, while the average pairwise
differences between those specimens and a single southern African T. cf. nobiliana (=T. cowleyi) was 27.6,
suggesting that these two forms are not conspecific. In their analysis, T. cf. nobiliana (=T. cowleyi) clustered more
closely to T. macnelli from Australia than to T. nobiliana from the western North Atlantic. However, electric rays in
general do not amplify very well with PCR (an issue currently under investigation by G. Naylor, College of
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Charleston, pers. comm.); further molecular data and analyses are needed to help elucidate the systematics of
Tetronarce.
Comparative material. Material of T. tokionis and T. formosa is listed in Ebert et al. (2013); other material
examined is provided in Carvalho et al. (2002). Tetronarce nobiliana: AMNH 4777, 885 mm TL adult (?) female,
off Morehead City, North Carolina, U.S.A., R. J. Coles, Mar. 1915; AMNH 44108, 715 mm TL subadult male,
Cape Lookout, North Carolina, U.S.A., R. J. Coles, Mar. 1915; AMNH 58255, 880 mm TL adult male, Cape Cod
Bay, Massachusetts, U.S.A., M. N. Feinberg, 19 Nov. 1986; AMNH 59728, 680 mm TL subadult female (no
further data). ANSP 426, 214 mm TL, immature male, Italy, C.L. Bonaparte, 1835 (syntype); ANSP 461 (2
specimens), 197 mm TL immature female with embryonic notches, 199 immature male, Italy, C.L. Bonaparte,
1835 (syntypes); MCZ 3604, 815 mm TL, male, Gulf of Maine, 12–15 miles off Plymouth, Massachusetts, U.S.A.,
60 m depth, 20 Nov. 1943; MLML uncatalogued, 825 mm TL, mature male, SSW Block Island, Rhode Island,
U.S.A., 40
o
57.5’ N, 71
o
35.9’ W, 75 m, 27 Aug. 2008; MNHN 0000-1309, juvenile, 186 mm TL, Algeria (holotype
of Torpedo nigra Guichenot, 1850); MNHN 1989-1538, 584 mm TL, preadult male, Sénegal, B. Séret; MNHN
1989-1540, 695 mm TL, adult male, Sénegal, 600 m, B. Séret; MNHN 1989-1541, 588 mm TL preadult female,
Sénegal, B. Séret; MNHN 1989-165, 535 mm TL preadult female, Sénegal, 250 m, B. Séret; MNHN 1989-1655,
352 mm TL juvenile female, Sénegal, 280 m, B. Séret; MNHN 1989-1658, 292 mm TL, juvenile female, Sénegal,
200 m, B. Séret. Tetronarce puelcha (all specs. from Brazil): UERJ 357, subadult male, 422 mm TL, Bom Abrigo,
state of São Paulo, 40–50 m, bottom trawl, Aug. 1995; UERJ 358, female, 475 mm TL (data as in UERJ 357);
UERJ 1631, female, 1005 mm TL, Itajaí, state of Santa Catarina, fishing vessel Ariogala, Jul. 1993; UERJ 1632,
female, 1047 mm TL (data as in UERJ 1631); UERJ 1714, female, 224 mm TL (data as in UERJ 357); UERJ 1233,
female, 873 mm TL, Macaé, state of Rio de Janeiro, 130 m, bottom trawl, Nov. 2004; UERJ 2099, subadult male,
623 mm TL, Ilha Grande, state of Rio de Janeiro, 10–30 m, bottom trawl, 2006; MZUSP 86748, subadult male, 240
mm TL, 24°51’06” S, 44°35’46” W, 400 m, R/V Soloncy Moura, Station 532, bottom trawl, 21 Oct. 2001; MZUSP
86769 (5 specs.), 3 subadult males, 291–321 mm TL, 2 juvenile females, 240–373 mm TL, 23°44’17” S,
42°12’06” W, 517 m, R/V Soloncy Moura, Station 606, bottom trawl, 26 Jun. 2002; MZUSP 86772, female, 425
mm TL, 26°54, 48’ S, 46°15,25’ W, 565 m, R/V Soloncy Moura, Station 411, bottom trawl, 19 Set. 2001; MZUSP
86773 (2 specs.), subadult male, 355 mm TL, juvenile female, 255 mm TL, 24°53’07” S, 44°32’55” W, 505 m, R/
V Soloncy Moura, Station 531 B, bottom trawl, 21 Oct. 2001; MZUSP 92444, female, 925 mm TL, 22°58’31” S,
42°03’29” W, state of Rio de Janeiro, 38–40 m, R/V Prof. W. Besnard, Station 7185 (1E), bottom trawl, 18 Feb.
2002; MZUSP 92445, female, 1202 mm TL, Barra de Cananéia, state of São Paulo, 60–112 m, bottom trawl, 11
Feb 2004; NUPEC 1171, female, 270 mm TL, Ilha Redonda, bottom trawl, Jul. 1999; NUPEC 1249, female, 380
mm TL, Ilha Redonda, bottom trawl, Jul. 1999; NUPEC 1376, subadult male, 474 mm TL, Laje de Santos, state of
São Paulo, bottom trawl, Oct. 1999; NUPEC 1445, subadult male, 485 mm TL, Ilha Bela, state of São Paulo,
bottom trawl, Nov. 1999; NUPEC 1467, subadult male, 386 mm TL, Santos, state of São Paulo, bottom trawl, Dec.
1999; NUPEC 1471, female, 382 mm TL, Santos, state of São Paulo, bottom trawl, Dec. 1999; NUPEC 1483,
female, 335 mm TL, Santos, state of São Paulo, bottom trawl, Dec. 1999; NUPEC 1500, female, 325 mm TL,
Santos, state of São Paulo, bottom trawl, Dec. 1999; NUPEC 1559, subadult male, 585 mm TL, between Juréia
(state of São Paulo) and Armação (state of Santa Catarina), bottom trawl, Jan. 2000.
Acknowledgements
The following individuals are sincerely thanked for their assistance and support: Leonard Compagno and Mike
Bougaardt (South African Museum); Eric Anderson, Paul Cowley, and Ofer Gon (South African Institute of
Aquatic Biodiversity); Rob Leslie (Marine and Coastal Management, Cape Town, South Africa); Dave Catania and
Jon Fong (California Academy Sciences); Robert C. Schelly, Barbara Brown, Radford Arrindell, and John Sparks
(AMNH); Mark Sabaj Pérez (Academy of Natural Sciences, Philadelphia); Jon Walsh (Moss Landing Marine
Laboratories); Andy Payne (Cefas); Barry Rose (Irvin and Johnson); Rob Leslie (Department of Agriculture,
Forestry, and Fisheries, Cape Town); Andrew Willston and Karsten Hartel (MCZ); Bernard Séret (MNHN); Eva
Berberich and Dave Jessup (California Department Fish and Wildlife); Sandra Downing and Lisa Natanson
(NOAA Fisheries, Northeast Fisheries Science Center); Ulisses L. Gomes (UERJ); and José L. de Figueiredo and
Michel Gianeti (MZUSP). Support for this project was provided by NOAA/NMFS to the National Shark Research
Zootaxa 3936 (2) © 2015 Magnolia Press
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Consortium and the David and Lucile Packard Foundation to the Pacific Shark Research Center. Additional support
provided by a National Science Foundation grant (DEB 1132229) to Gavin Naylor, College of Charleston. MRC is
supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) through grants 2012/09877-0,
2012/02349-5 and 2012/05391-5, and the Conselho Nacional de Desenvolvimento Científico e Tecnológico
(CNPq) (304615/2011-0).
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... Smale et al. 2002; Ebert and Compagno 2007, 2009; Aschliman et al. 2010; Kemper et al. 2010; Ebert et al. 2011; Ebert and Cailliet 2011; Ebert et al. 2015). Despite this large level of biodiversity and endemism, our knowledge of South African chondrichthyans is relatively scarce (Compagno 1999; Ebert and van Hees 2015). Furthermore, approximately one-third of the southern African species are classified as rare and are known from less than 10 records of each species (RSA 2014). ...
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