Scyliorhinus cervigoni Maurin & Bonnet, 1970

Soares, Karla D. A. & De, Marcelo R., 2019, The catshark genus Scyliorhinus (Chondrichthyes: Carcharhiniformes: Scyliorhinidae): taxonomy, morphology and distribution, Zootaxa 4601 (1), pp. 1-147 : 42-50

Scyliorhinus cervigoni Maurin & Bonnet, 1970

( Figs. 28–33 , Tabs. 3 , 8, 9 )

Common names: West African catshark ( United Kingdom), Roussette Thalassa ( France), Alitán africano ( Spain).

Scylliorhinus [sic] stellaris: Cadenat, 1950: 87 (catalogue, Senegal).

Scyliorhinus sp.: Cervigón, 1960: 33 –41 (catalogue, western coast of Africa).

Scyliorhinus stellaris: Poll, 1951: 21 , figs. 3–4, pl. 13 (catalogue, Southeastern Atlantic); Cadenat & Blache, 1981: 178 –181, fig. 121a (only part referring to the Senegal specimens); Wirtz et al., 2013: 115 (listed, islands of Green Cape); Compagno, 2016: 1263 (only records attributed to S. cervigoni ).

Scyliorhinus cervigoni Maurin & Bonnet, 1970: 129 , fig. 3 (original description, type locality: Senegal); Springer, 1979: 133 –135, fig. 85 (taxonomic review); Compagno, 1984: 361 (FAO catalogue); Compagno, 1999: 480 (listed); Compagno et al., 2005: 248 –249, pl. 41 (compilation); Ebert et al., 2013a: 373, 379, pl. 51 (compilation); Ebert & Mostarda, 2015: 48 (listed); Carpenter & Angelis, 2016: 1266 (catalogue, Eastern Central Atlantic); Weigmann, 2016: 43 (listed).

Neotype. ZMH 102563, male, 623.1 mm TL ( Senegal, 15°56’N, 16°57’W, 140–250 m depth). [designated herein].

Additional material examined. 21 specimens (see Appendix).

Diagnosis. Scyliorhinus cervigoni differs from all congeners by presenting a color pattern with dark spots greater than spiracles (vs. dark spots absent in S. capensis , S. comoroensis , S. hesperius , S. meadi , S. torazame , and S. torrei ; reticulate pattern in S. retifer ; dark spots smaller than spiracles in S. boa , S. cabofriensis and S. canicula ); median dorsal line formed by dark spots two times greater than spiracles (vs. spots smaller than two times spiracles in S. haeckelii ; absent in the other species); crown of dermal denticles two times longer than wide (vs. less than two times in other species); clasper with cover rhipidion not covered by dermal denticles (vs. cover rhipidion covered in other species, except in S. boa , S. hesperius and S. retifer ). The following combination of characters, although less conspicuous, also helps distinguish this species: dark spots restricted to saddles (vs. distributed along the body in S. cabofriensis and S. canicula ); anterior nasal flaps reaching the upper lip (vs. flaps distant from lips in other species, except S. canicula , S. comoroensis , S. duhamelii , S. garmani , and S. stellaris ); nasoral grooves absent and posterior nasal flaps situated on the posterior edge of excurrent apertures (vs. grooves present and flaps situated laterally only in S. canicula and S. duhamelii ); mesonarial ridge not extending beyond the posterior edge of anterior nasal flap (vs. exceeding it in S. stellaris ); mandibular canal of lateral line system with 5–6 pores (vs. 3–4 in S. hesperius ); oral canal of lateral line system with 9–10 pores (vs. 5–6 in S. hesperius ; 10–12 in S. duhamelii ; 9–13 in S. torrei ); commissural teeth presenting one cusplet and principal cusp laterally situated (vs. two or more in other species, except S. torazame and S. torrei ); interdorsal space 0.6–1.0 times the anal fin base (vs. greater than anal base in S. boa , S. cabofriensis , S. haeckelii , S. hesperius , S. meadi , S. retifer , S. torrei , and S. ugoi ); pelvic fins subtriangular (vs. subrectangular in S. garmani and S. stellaris ); pelvic apron extending to 2/3 of pelvic inner margins (vs. extending for almost the entire length in S. canicula , S. capensis , S. duhamelii , S. torazame , and S. torrei ); clasper with smooth terminal dermal cover (vs. rough in S. canicula and S. capensis ); terminal 3 cartilage absent (vs. present in S. boa , S. canicula , S. capensis , S. retifer , and S. torazame ); dorsal terminal 2 cartilage reduced and subtriangular (vs. elongated in S. boa , S. canicula , S. comoroensis , S. duhamelii , S. retifer , S. stellaris , S. torazame , and S. torrei ); counts of monospondylous vertebrae 40–45 (vs. 34–40 in S. canicula ; 44–46 in S. capensis ; 35–37 in S. duhamelii ; 48 in S. garmani ; 36–40 in S. haeckelii ; 46–48 in S. meadi ; 43–47 in S. stellaris ; 32–37 in S. torazame ; 30–35 in S. torrei ; 38–39 in S. ugoi ); adult males between 623–665 mm TL (vs. adult males smaller than 500 mm TL in S. boa , S. cabofriensis , S. canicula , S. comoroensis , S. duhamelii , S. haeckelii , S. hesperius , S. retifer , S. torazame , and S. torrei ).

Description. Morphometric and meristic data are given in Table 8, and neurocranial measurements in Table 9 .

Body robust, tapering considerably posterior to cloaca ( Fig. 28 ). Prepectoral length 0.4–0.6 (0.4) times prepelvic length. Trunk shorter than tail; snout-vent length 0.9–1.0 (1.0) times vent-caudal length. Pectoral-pelvic space 1.4–1.6 (2.1) times the pelvic-anal space. Interdorsal space 1.6–2 (1.6) times the dorsal-caudal space ( Tab. 8). No interdorsal, postdorsal or postanal ridges; lateral crest on caudal peduncle absent.

Head broad and robust; head length 1.7–2.0 (1.8) times its width ( Fig. 28 ). Snout relatively short, preoral length 0.5–0.9 (0.5) times mouth width and 0.6–1.1 times smaller than preorbital length. Prenasal length 0.6 times internarial space; preorbital length 0.9–1.0 (1.2) times interorbital space.

Eye large and slitlike, eye length 1.8–4.3 (3.9) times its height and 0.1–0.2 (0.2) times smaller than head length ( Figs. 28 , 29 ). Eye dorsolateral on head, with lower edge medial to horizontal head rim in dorsal view; subocular ridge strong. Nictitating lower eyelid of rudimentary type, with shallow subocular pouch and secondary lower eyelid free from upper eyelid. Spiracle close behind but well separated from eyes, dorsolaterally on head and somewhat lower than level of eye notch. Spiracle diameter goes 2.8–4.3 (4.8) times in eye length and 6–10.4 (6.7) times in interorbital distance.

First two gill openings about equally wide; first one twice as long as fifth. All gill openings slightly concave and not elevated on dorsolateral surface of head; gill filaments not visible externally.

Nostril with broad incurrent aperture, without nasoral groove or nasal barbel, and small and oval excurrent aperture. Anterior nasal flap large, triangular, and covering posterior nasal flap and excurrent aperture, touching the upper lip ( Figs. 29 A–B). Mesonarial ridge distinct but not exceeding the posterior border of the anterior nasal flap. Posterior nasal flap rectangular, situated on the posterior border of the excurrent aperture and corresponding to 1/3 of the anterior flap. Mesonarial superior and inferior flaps triangular and 1/3 of anterior nasal flap. Internarial distance 0.7–0.8 (0.8) times smaller than interorbital distance.

Mouth arched, moderately large and short, its length goes 1.4–1.9 (1.4) times in mouth width ( Figs. 29 A–B). Lower labial furrow short and narrow, 3.6–4.9 (4.7) times smaller than mouth width. Dorsal labial cartilage 1.3 times the ventral cartilage; anterior tip of dorsal labial cartilage reaching the orbital process of the palatoquadrate. Tongue flat and rounded, light-colored, with oral papillae hardly detectable.

Monognathic heterodonty gradual well developed; anterior teeth abruptly larger than the parasymphysial ones and lateral teeth smaller distally, with smaller and thicker principal cusps ( Fig. 30 ). Sexual heterodonty not observed; only male specimens examined. Tooth counts 21–29 23–29/20–26 21–27. Parasymphysial teeth with a principal cusp flanked by one cusplet on each side; cusplets 1/3 the height of the principal cusp and half the width of it. Protuberances present on the crown base and striae running from the crown base to the apex of the principal cusp. Anterior teeth similar in shape to parasymphysial ones; principal cusp four times higher than cusplets. Protuberances in crown base poorly developed and striae throughout the crown. Lateral teeth with three cusplets; two at the mesial edge and one at the distal edge. Lateral upper teeth with proximal mesial and distal cusplets larger and corresponding to half the height of the principal cusp and median portion of root more concave; lower teeth with cusplets smaller and concavity of root less prominent. Principal cusp slightly oblique in both jaws. Protuberances present in the crown base and striae extending throughout the crown. Commissural teeth with one cusplet and principal cusp stronger, slightly oblique and laterally situated. Protuberances well prominent and striae extending throughout the crown. Ectodermal pits present in lateral and commissural teeth, restricted to the crown base.

Lateral trunk denticles with flat, elongated dagger-shaped crowns, 2–2.2 times longer than wide ( Tab. 3 ); principal cusp two times longer than cusplets and anterior part covered with ectodermal pits. Dermal denticles of all regions with five ridges; median and lateral ones well prominent and running throughout the principal cusp length ( Fig. 31 ).

Pectoral base 0.7 times mouth width ( Fig. 29C ). Pectoral anterior margin 2.1–2.4 (2.4) times its base and 1.5–2.3 (1.5) times the posterior margin. Pectoral fin skeleton aplesodic with radials mostly divided into three segments. Propterygium and mesopterygium trapezoidal; the former smaller than the latter. Propterygium with one proximal segment; mesopterygium with 3–4 proximal segments fused proximally. Metapterygium with 11 proximal segments. Metapterygial axis rectangular and corresponding to 1/5 of metapterygium.

Pelvic fin trapezoidal ( Fig. 29F ); pelvic anterior margin 1.1–1.2 (1.1) times the posterior margin and 1.1–1.2 (1.1) times the pelvic base. Pelvic inner margins of males fused 2/3 of their extension; claspers of juveniles evident without lifting the pelvic apron.

Clasper short and cylindrical, sometimes extending beyond free rear tips of pelvic fins; clasper inner length 0.6–01.6 (1.6) times the pelvic anterior margin, 1.9–2.6 (1.7) times clasper outer length and 4.8–5.9 (5.7) times the clasper base. Most of clasper surface except apopyle, dorsomedial surface of glans, cover rhipidion, rhipidion, and terminal dermal cover, covered by dermal denticles with anteriorly directed crowns ( Fig. 32A ). Clasper hooks absent. Rhipidion well-developed, partly covered medially by a prominent exorhipidion and anteriorly by the cover rhipidion; insertion of rhipidion at anterior portion of terminal dorsal 2 cartilage and extending to the end of glans. Cover rhipidion notched in the anterior portion and expanded medially, reaching a nearly straight and poorly developed exorhipidion; both cover rhipidion and exorhipidion covering the clasper groove. Envelope inconspicuous; pseudosiphon distinct and robust. Terminal dermal cover smooth and extending through 1/3 of the glans, covering the posterior borders of rhipidion and exorhipidion.

Clasper skeleton relatively simple ( Fig. 32B ). Ventral marginal cartilage shorter than dorsal one; ventral terminal beginning anteriorly, but ending together with the dorsal terminal. Terminal 3 cartilage absent. Dorsal terminal 2 cartilage conical, dorsally projected and situated between the dorsal marginal and terminal 2 cartilages. Ventral terminal 2 cartilage featherlike, robust and corresponding to one half-length of ventral terminal cartilage; ventral terminal 2 beginning at the same level as the dorsal terminal 2 cartilage.

First dorsal fin subrectangular or triangular, with nearly straight anterior margin, rounded apex and angular free rear tip ( Fig. 28 ). First dorsal fin origin opposite or slightly posterior to the insertion of pelvic fin and its insertion above the anterior third of pelvic-anal distance. Anterior margin 1.5 times first dorsal fin base; first dorsal fin height 0.7 times its base.

Second dorsal fin smaller than the first and trapezoidal or subrectangular ( Fig. 28 ). Second dorsal fin origin opposite to half-length of anal fin base and its insertion opposite to posterior tip of anal fin. Anterior margin 1.3 times base of second dorsal fin; second dorsal base 1.6–1.7 (1.6) times its height and 0.7–0.9 (0.7) times the dorsalcaudal distance. First dorsal fin 1.3–1.4 (1.4) times larger than the second dorsal fin.

Anal fin triangular, apically narrow and not falcate ( Fig. 28 ); anal fin base 1.6–2.5 (1.5) times the second dorsal fin base. Anal anterior margin nearly straight, apex narrowly rounded, free rear tip acutely pointed, and inner margin straight. Anal fin base 1.1–1.2 (1.1) times the interdorsal distance and 1.9–2.4 times the dorsal-caudal distance. Anal anterior margin 1.7–1.9 (1.7) times the posterior margin; anal fin height 0.4–0.5 (0.4) times its base.

Caudal fin narrow-lobed and asymmetrical ( Fig. 28 ). Dorsal caudal lobe 1.9–2.1(1.9) times larger than preventral lobe; subterminal caudal margin as long as the terminal margin. Caudal crest of enlarged denticles absent on caudal fin margins.

Neurocranium broad, corresponding to 10.9% TL (only on male specimen dissected). Rostrum length corresponding to 1.5 times the distance between lateral rostral cartilages. Nasal capsules as long as wide. Anterior fontanelle and basal plate similar in width. Orbital region 2.1 times smaller than the nasobasal length. Optic capsule length 1.3 times smaller than the nasobasal length and width across the optic capsules 3.7 times its length. Width across postorbital processes 1.1 times the preorbital processes width ( Tab. 9 ).

Coloration in alcohol. Body beige with six or seven inconspicuous saddles, slightly darker than the background color ( Fig. 28 ). Dark spots two times larger than the spiracles, forming a dorsomedial row with one spot for each saddle. Dark spots larger or similar to spiracles on lateral surfaces and becoming smaller on dorsal surfaces, distributed along the body and not bordering saddles. Spots predominantly inside saddles, but also in between them. Spots present on the dorsal surface of paired fins and dorsal fins. Light spots absent. Belly and ventral surface of paired and anal fins without spots, cream in color.

Distribution. This species is distributed along the Southeastern Atlantic, from Arguim, Mauritania (20°31’N) to central coast of Angola (12°36’S). Positive records of occurrence exist from Senegal, Guinea Bissau, Liberia, Ghana, Nigeria, Cameroon and Gabon ( Fig. 33 ).

Biological data. Adult males between 623–665 mm TL; largest male examined 665 mm TL. Adult females not examined; largest female, 588 mm TL, still immature. Largest size reported 76 cm ( Compagno et al. 2005; Ebert et al. 2013a; Carpenter & Angelis 2016). Egg capsules measure 80 mm length and 30 mm width. This species is a benthic dweller in depths of 45–500 m, mostly between 150– 260 m. Conservation Status ‘Data Deficient’ ( Burgess 2006).

Etymology. The specific name ‘cervigoni’ was dedicated to Fernando Cervigón, first researcher to report it as a new species.

Remarks. Scyliorhinus cervigoni was described by Maurin & Bonnet (1970), based on a 380 mm TL female captured at north from Cayar, Senegal, in 270–430 m depth. The authors did not provide information about the institution in which the type specimens were housed and, according to Fricke et al. (2018), they were lost. Due to a history of misidentifications and confusing identity between S. cervigoni and S. stellaris , the designation of a neotype is justified here.

Records of occurrence for Mauritania, Arguim (20°31’N, 75–90 m depth) and Tamxat (17°18’N, 190 m depth), were reported by Maurin & Bonnet (1970) and represent the northernmost records of the geographic range of S. cervigoni . These records are here considered to be reliable although no specimen from this region were examined. Compagno (2016) pointed out that nominal records of S. stellaris from southern Senegal could be based on S. cervigoni , and specimens of S. cervigoni from this area were observed during this study (see Appendix). Specimens examined for the present revision indicate that the geographic distribution of S. stellaris does not extend to the northwestern coast of the African continent and, therefore, this species do not overlap with S. cervigoni .

Figures

FIGURE 28. Neotype of Scyliorhinus cervigoni, ZMH 102563, male, 623.1 mm TL (Senegal). A, dorsal view; B, lateral view. Scale bar = 20 mm.

FIGURE 29. Scyliorhinus cervigoni. A, D, F, ZMH 102588, female, 587.4 mm TL (Senegal, 15°51’N, 16°56’W); B, SAIAB 64847, male, 662 mm TL (Angola, 7°10’S, 11°59’E); C, E, USNM 221597, female, 246 mm TL (Gana, 5°6’N, 00°17’W). A, B, ventral view of head; C, detail of pectoral fins; D, lateral view of head; E, dorsal view of head; F, detail of pelvic fins. Scale bar = 20 mm.

FIGURE 30. Teeth of Scyliorhinus cervigoni; labial view, USNM 221599, male, 283 mm TL. a, anterior teeth; c, commissural; l, lateral; ps, parassymphysial. Scale bar = 100 µm.

FIGURE 31. Dermal denticles of Scyliorhinus cervigoni, USNM 221599, male, 283 mm TL (Guinea Bissau, 10°44’N, 17°06’W). A, region above pectoral fin base; B, region below first dorsal fin origin; C, region below second dorsal fin insertion. Scale bar = 250 µm.

FIGURE 32. Clasper of Scyliorhinus cervigoni; dorsal view, SAIAB 64847, 662 mm TL (Angola, 7°10’S, 11°59’E). A, external morphology; B, skeleton. crh, cover rhipidion; en, envelope; end, endstyle; erh, exorhipidion; hp, hipopyle; rd, dorsal marginal cartilage; rh, rhipidion; rv, ventral marginal cartilage; td, dorsal terminal cartilage; td2, dorsal terminal 2 cartilage; tdc, terminal dermal cover; tv, ventral terminal cartilage; tv2, ventral terminal 2 cartilage. Scale bar = 10 mm.

FIGURE 33. Map showing the geographic distribution of Scyliorhinus cervigoni based on material examined in this study. Black star indicates the neotype locality.

Tables

TABLE 8. Morphometric and meristic data of Scyliorhinus cervigoni. SD, standard deviation; n, number of examined specimens. Total length (TL) in mm, other measurements as percentages of TL.

Characters	Neotype	n	Range	Mean	SD
Total length (TL)	623	21	115.9—664.7	342.7	115.9
Precaudal length	78.6	20	73.6–79.3	76.3	2.1
Eye-spiracle length	0.9	21	0.7–1.9	1.3	0.3
Prenasal length	3.0	21	2.6–4.7	3.5	0.6
Preoral length	4.5	21	4.0–10.6	5.9	1.4
Preorbital length	7.2	21	6.5–9.4	7.7	0.8
Prespiracular length	11.8	21	11.0–14.9	12.1	1.0
Prebranchial length	18.4	21	15.8–19.6	17.8	2.9
Head length	23.8	21	20.1–31.2	23.6	2.4
Prepectoral length	21.7	21	18.9–37.5	22.3	4.0
Prepelvic length	48.5	21	37.8–57.0	43.3	4.1
Snout-vent length	52.3	21	42.2–61.4	47.2	4.3
Vent-caudal length	50.4	21	42.3–67.7	53.8	4.9
Pre-first dorsal length	55.4	19	44.3–55.4	51.2	5.2
Interdorsal distance	9.0	21	7.8–11.4	9.1	0.8
Dorsal-caudal distance	5.7	21	3.8–6.8	5.2	0.9
Pectoral-pelvic distance	19.9	21	13.6–22.5	16.8	2.1
Pelvic-anal distance	9.3	20	8.3–16.1	10.5	1.7
Anal-caudal distance	5.5	21	4.6–8.6	6.4	1.1
Interorbital distance	6.0	21	6.0–10.4	8.3	1.0
Internarial distance	4.6	21	4.6–7.2	5.8	0.5
Mouth length	6.5	21	4.3–8.0	5.9	0.8
Mouth width	8.4	21	8.3–11.3	9.5	0.8
Lower labial furrow length	1.8	21	1.7–3.1	2.3	0.3
Eye length	4.3	21	3.5–4.7	4.1	0.3
Eye height	1.1	21	0.8–2.6	1.7	0.5
Spiracle length	0.9	21	0.8–1.7	1.0	0.2
First gill slit height	3.6	21	2.7–4.3	3.6	0.7
Fifth gill slit height	2.1	21	1.1–2.5	1.9	0.4

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