Scyliorhinus torrei Howell-Rivero, 1936

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 : 118-125

Scyliorhinus torrei Howell-Rivero, 1936

( Figs. 87–92 , Tabs. 3 , 18 , 19)

Common name: dwarf catshark ( United States).

Scylliorhinus torrei Howell-Rivero, 1836: 43 , pl. 9 (original description, type locality: Havana, Cuba).

Scyliorhinus torrei: Bigelow & Schroeder, 1948: 211 , figs. 34, 35 (catalogue, Northwestern Atlantic); Springer & Bullis, 1956: 40 (catalogue, Gulf of Mexico); Bullis & Thompson, 1965: 17 (catalogue, eastern coast of United States); Springer, 1966: 598, figs. 4a, 7c, 14a (taxonomic review); Springer & Sadowsky, 1970: 85 (taxonomic review, Western Central Atlantic); Springer, 1979: 146 –147, fig. 97 (taxonomic review); Cadenat & Blache, 1981: 181 –183, fig. 123b (catalogue, western Africa); Compagno, 1984: 368 –369 (FAO catalogue); Compagno, 1999: 480 (listed); Kiraly et al., 2003: 16 (catalogue, Atlantic coast of United States); Bunkley-Williams & Williams, 2004: 95 –96, fig. 3 (catalogue, Caribbean Sea); Compagno et al., 2005: 254, pl. 42 (compilation); Castro, 2011: 347 –348, figs. 91a–e (catalogue, North America); Kyne et al., 2012: 59 (catalogue, North America and Caribbean Sea); Ebert et al., 2013a: 374, 384, pl. 52 (compilation); Gutierrez et al., 2015: 44 (catalogue, Cuba); Weigmann, 2016: 44 (listed).

Holotype. MCZ 1457 , female, 250 mm TL (Havana, Cuba).

Additional material examined. 38 specimens (see Appendix).

Diagnosis. Scyliorhinus torrei differs from all its congeners by presenting a body light brown to caramel with spots beige to cream colored (vs. light spots absent in S. cervigoni , S. garmani , S. meadi , and S. retifer ; yellow to golden spots in S. capensis ; body beige or cream in S. boa , S. cabofriensis , S. canicula , S. comoroensis , S. duhamelii , S. haeckelii , S. hesperius , S. stellaris , S. torazame , and S. ugoi ); pelvic apron extending through almost the entire length of pelvic inner margins (vs. pelvic apron extending to 2/3 length of pelvic inner margins in S. boa , S. cabofriensis , S. cervigoni , S. comoroensis , S. haeckelii , S. hesperius , S. meadi , S. retifer , S. stellaris , and S. ugoi ); counts of monospondylous vertebrae 30–35 (vs. greater values in other species, except S. torazame ); smallest species of the genus, with adult males at least 269 mm TL and adult females at least 294 mm TL (vs. much greater sizes at sexual maturity in other species). The following combination of characters, although less conspicuous, also helps distinguish this species: saddles darker than the background only in juveniles (vs. prominent in adults of S. canicula , S. capensis , S. comoroensis , S. haeckelii , S. hesperius , S. meadi , S. stellaris , S. torazame , and S. ugoi ); spots predominantly greater than spiracles all over the body (vs. predominantly smaller in S. boa , S. cabofriensis , S. canicula , S. duhamelii , S. stellaris , and S. ugoi ); anterior nasal flaps not reaching the upper lip (vs. flaps reaching the lip, and sometimes covering it, in S. canicula , S. cervigoni , S. comoroensis , S. duhamelii , S. garmani , and S. stellaris ); interdorsal distance greater than the anal base (vs. smaller or equal to anal base in S. canicula , S. capensis , S. cervigoni , S. comoroensis , S. duhamelii , S. garmani , S. stellaris , and S. torazame ); mandibular canal of lateral line system with 5 to 8 pores (vs. 4–6 in other species, except in S. stellaris ); oral canal of lateral line system with 9–13 pores (vs. 5–6 in S. hesperius ; 7–10 in other species, except S. duhamelii ); commissural teeth with one cusplet and principal cusp laterally situated (vs. two in S. retifer and S. stellaris ; three or more in S. boa , S. canicula and S. hesperius ); clasper with terminal dermal cover smooth (vs. rough in S. canicula and S. duhamelii ); cover rhipidion covered by dermal denticles (vs. no denticles in S. boa , S. cervigoni , S. hesperius and, S. retifer ); terminal 3 cartilage absent (vs. present in S. boa , S. canicula , S. capensis , S. retifer , and S. torazame ); dorsal terminal 2 cartilage elongated and corresponding to 1/4 of dorsal terminal cartilage (vs. reduced and subtriangular in S. cabofriensis , S. capensis , S. cervigoni , S. haeckelii , and S. ugoi ; 1/3 of dorsal terminal cartilage in S. boa and S. comoroensis ; same length in S. torazame ); upper tooth rows 33–42 (vs. 45–58 in S. cabofriensis ; 46–76 in S. capensis ; 44–58 in S. cervigoni ; 50 in S. comoroensis ; 46 in S. garmani ; 48–54 in S. haeckelii ; 46–54 in S. meadi ; 47–56 in S. ugoi ); lower tooth rows 28–42 (vs. 44-50 in S. cabofriensis ; 48–85 in S. capensis ; 43 in S. comoroensis ; 44 in S. garmani ; 43–49 in S. meadi ; 43–53 in S. ugoi ).

Description. Morphometric and meristic data are given in Table 19, and neurocranial measurements in Table 18 .

Body slender and cylindrical, tapering considerably posterior to cloaca ( Fig. 87 ). Prepectoral length 0.4–0.5 times the prepelvic length. Trunk shorter than tail; snout-vent length 0.7–0.8 (0.8) times vent-caudal length. Pectoral-pelvic space 1.2–1.4 (1.5) times the pelvic-anal space. Interdorsal space 1.8–2.2 (2.0) times the dorsalcaudal space ( Tab. 19). No interdorsal, postdorsal or postanal ridges; lateral crest on caudal peduncle absent.

Head moderately broad and depressed; head length 0.9–1.7 (2.1) times head width ( Fig. 87 ). Snout relatively short, preoral length 0.5–0.6 times mouth width and 1.0–1.7 (1.4) times smaller than preorbital length. Prenasal length 0.4–0.5 (0.6) times internarial space; preorbital length 0.8–0.9 (0.9) times interorbital space.

Eye large and slitlike, eye length 2.0–2.6 (2.5) times its height and 0.3–0.5 (0.2) times smaller than head length ( Fig. 87 ). 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 3.4–4.8 (4.0) times in eye length and 6.9–10.8 (7.5) times in interorbital width.

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, covering posterior nasal flap and excurrent aperture, and extending just anterior to mouth, close to the upper lip but not touching it ( Figs. 88 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. Mesonarial superior and inferior flaps triangular and corresponding to 1/3 of anterior nasal flap. Internarial space 1.4–1.5 (1.3) times smaller than interorbital space.

Mouth arched, moderately wide and short, its length goes 1.5–1.7 (1.6) times in mouth width ( Figs. 88 A–B). Lower labial furrow short and narrow, 3.5–3.9 (4.3) 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. 89 ). Sexual heterodonty not observed; only adult males examined. Tooth counts 16–21 17–21/ 15–20 1 15 –21 (21–21/ 20–1–20). Parasymphysial teeth with a principal cusp flanked by one cusplet on each side; cusplets 2/3 the width of the principal cusp. Protuberances on medial portion of the crown base and striae restricted to the crown base. Anterior teeth larger than the parasymphysial and principal cusp less stout. Anterior teeth with two to four cusplets; marginal cusplets when present in upper teeth less developed than in lower ones. Proximal cusplets shorter, half or less the height of the principal cusp in upper teeth and more than half the height in lower ones. Protuberances on the crown base; striae extending through almost the entire crown and more prominent in upper teeth. Lateral teeth with three cusplets; two cusplets at the mesial edge and one at the distal edge. Mesial proximal and distal cusplets corresponding to half the height of the principal cusp; marginal cusplet half the height of proximal one. Protuberances inconspicuous; striae restricted to the crown base. Commissural teeth with one cusplet; principal cusp stouter and laterally situated. Cusplet 2/3 the height and half the width of the principal cusp. Protuberances on the crown base and striae throughout the crown. Ectodermal pits present in lateral and commissural teeth, restricted to the crown base.

Lateral trunk denticles with flat, elongated teardrop-shaped crowns, 1.4–2.1 times as long as wide ( Tab. 3 ); anterior part covered with ectodermal pits. Crown with a strong medial ridge extending its entire length onto long principal cusp. Dermal denticles above the pectoral fin with no lateral and marginal ridges. Denticles below dorsal fins longer and with prominent medial and lateral ridges extending throughout the crown; marginal ridges present ( Fig. 90 ).

Pectoral base 0.7 (0.8) times mouth width ( Fig 88C ). Pectoral anterior margin 2–2.3 (2.0) times its base and 1.7–2.0 (1.7) 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 7–8 segments. Metapterygial axis rectangular and corresponding to 1/5 of metapterygium.

Pelvic fin subtriangular in males and trapezoidal in females ( Fig. 88F ); pelvic anterior margin 1–1.2 (0.9) times the posterior margins and 0.8–1 (0.8) times the pelvic base. Pelvic inner margins of males fused by almost all their extension, with sharp edges; claspers of juveniles involved by the pelvic apron and evident only with lifted apron.

Clasper short and cylindrical ( Fig. 88F ), sometimes extending beyond free rear tips of pelvic fins; clasper inner length 0.7–1 time the pelvic anterior margin, 1.6–2.3 times the clasper outer length and 3.7–4.6 times the clasper base. Most of clasper surface except dorsomedial surface of glans, envelope, medial border of cover rhipidion, rhipidion, and terminal dermal cover, covered by dermal denticles with anteriorly directed crowns ( Fig. 91A ). 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 dorsal terminal 2 cartilage and extending to the end of glans. Cover rhipidion with a nearly straight margin, and covered medially by the exorhipidion; both cover rhipidion and exorhipidion covering the clasper groove. Envelope well developed and with posterior border separated from the exorhipidion, covering the anterior border of the cover rhipidion; pseudosiphon poorly developed, visible only internally. Terminal dermal cover smooth extending for 1/3 of the ventral terminal cartilage and covering the posterior borders of exorhipidion and cover rhipidion.

Clasper skeleton relatively simple ( Fig. 91B ). Ventral terminal cartilage beginning anteriorly, but ending together with the dorsal terminal. Terminal 3 cartilage absent. Dorsal terminal 2 cartilage small and rodlike, situated between the dorsal marginal and terminal cartilages; corresponding to 1/4 the length of dorsal terminal. Ventral terminal 2 cartilage rodlike with tapered anterior and posterior tips and corresponding to half of the ventral terminal cartilage; ventral terminal 2 cartilage beginning at half of the dorsal terminal 2.

First dorsal fin triangular, with nearly straight anterior margin, rounded apex and angular free rear tip ( Fig. 87 ). First dorsal fin origin opposite to the half of pelvic inner margin. First dorsal fin insertion opposite to the anterior 2/ 5 of the pelvic-anal distance. Anterior margin 1.2–1.3 (1.4) times first dorsal fin base; first dorsal fin height 0.6–0.7 (0.7) times its base.

Second dorsal fin smaller than the first and triangular, similar in size and shape to anal fin ( Fig. 87 ). Second dorsal fin origin opposite to the posterior 1/3 of anal base; insertion posterior to the posterior tip of anal fin. Anterior margin 1.2 times base of second dorsal fin; second dorsal base 1.9 (2.3) times its height and 0.9–1.3 (1.3) times the dorsal-caudal distance. First dorsal fin 1.4–1.6 (1.4) times larger than the second dorsal fin.

Anal fin triangular, apically narrow and not falcate ( Fig. 87 ); anal fin base 1.6–1.7 (1.6) times the second dorsal fin base. Anal fin anterior margin nearly straight, apex narrowly rounded, free rear tip acutely pointed, and inner margin straight. Anal fin base 0.8–0.9 (1.0) times the interdorsal distance and 1.5–2.1 (2.0) times the dorsalcaudal distance. Anal fin anterior margin 1.3–3 (1.5) times the posterior margin; anal fin height 0.4 times its base.

Caudal fin narrow-lobed and asymmetrical ( Fig. 87 ). Dorsal caudal lobe 1.8–2.2 (1.9) times larger than preventral lobe; subterminal caudal margin 1–1.1 (0.9) times the terminal margin. Caudal crest of enlarged denticles absent on caudal fin margins.

Neurocranium broad and somewhat flattened, corresponding to 9.1–9.8% TL. Rostrum length 1.2–1.7 times the distance between lateral rostral cartilages. Nasal capsule wider than long, oval-shaped and expanded laterally; width 1.1 times its length. Anterior fontanelle broad and subrectangular in males (females not available for dissection); epiphyseal notch very prominent. Basal plate flat with narrow borders, its width 1.9–2 times smaller than nasobasal length. Orbital region 2–2.4 times smaller than nasobasal length. Otic capsule short, its length 3–4.3 times smaller than nasobasal length and width 2.3–2.7 times otic capsule length. Width across postorbital processes 1.2–1.4 times the preorbital processes width ( Tab. 18 ).

Coloration in alcohol. Holotype with body cream colored and spots slightly lighter than the background ( Fig. 87 ). Other specimens present a body light brown to caramel with spots beige to cream. Seven to eight saddles are present, darker than the background color in juveniles and inconspicuous or absent in adults ( Fig. 88 ). Spots rounded, greater than spiracles and randomly distributed on the body. Dorsal, pelvic and anal fins without spots; caudal fin presenting few spots. Belly and ventral surface of paired fins without spots, cream in color.

Distribution. This species is distributed around the southeastern coast of Florida and eastern Florida Strait (28°N), off western Bahamas, from Havana to Sancti Spiritus, northern Cuba, and in the Virgin Islands and Playa Santa, Porto Rico ( Fig. 92 ).

Biological data. Adult male 269 mm TL; largest male examined 290 mm TL. Adult female 294 mm TL. Maximum size reported for females 320 mm TL ( Compagno et al., 2005); this is the smallest species of the genus. It is a benthic dweller in depths of 180–591m ( Bunkley-Williams & Williams, 2004). Conservation status ‘Least Concern’ ( Sherrill-Mix & Burgess, 2009).

Remarks. Howell-Rivero (1936: 43) described this species from a 250 mm TL female, presenting ‘both ground color and darker blotches covered with small white spots, nearly as large as pupil, irregularly distributed’. However, the illustration of the holotype (pl. 9) presents only the spots inside the saddles, which could be confused with the color pattern presented in S. hesperius . According to examined material, juvenile specimens of S. torrei present saddles more conspicuous than adults and in some cases saddles are absent. Also, the ground color of S. torrei is a light brown to caramel while in S. hesperius it is beige.

The color pattern of this species is very similar to the pattern found in Schroederichthys maculatus . These species can be distinguished by numerous characters such as anterior nasal flaps with straight posterior border in S. torrei vs. forked and divided into two portions in S. maculatus , upper labial furrows absent (vs. present in S. maculatus ), first dorsal fin greater than second one (vs. dorsal fins similar in size in S. maculatus ) and caudal region only slightly greater than the body (vs. caudal region 1/3 greater in S. maculatus ). Other characters found in internal structures (e.g. claspers and neurocranium) also help distinguish both species.

Figures

FIGURE 87. Holotype of Scyliorhinus torrei Howell-Rivero, 1936, MCZ 147, female, 250 mm TL (Havana, Cuba). A, ventral view; B, lateral view. Scale bar = 20 mm.

FIGURE 88. Scyliorhinus torrei. A, CAS 65845, female, 255 mm TL (Cuba, 23°34’N, 79°07’W); B–F, USNM 157852, male, 285 mm TL (Cuba, 22°55’N, 79°27’W). A, B, ventral view of head; C, lateral view of head; D, lateral view of head; E, dorsal view of head; F, detail of pelvic fins and claspers. Scale bar = 10 mm.

FIGURE 89. Teeth of Scyliorhinus torrei; labial view, USNM 157852, male, 285 mm TL (Cuba, 22°55’N, 79°27’W). a, anterior tooth; c, commissural; l, lateral; ps, parassymphysial. Scale bar = 100 µm.

FIGURE 90. Dermal denticles of Scyliorhinus torrei. A–C, CAS 65845, female, 255 mm TL (Cuba, 23°34’N, 79°07’W); D–F, USNM 157852, male, 285 mm TL (Cuba, 22°55’N, 79°27’W). A, D, region above pectoral fin base; B, E, region below first dorsal fin origin; C, F, region below second dorsal fin insertion. Scale bar = 250 µm.

FIGURE 91. Clasper of Scyliorhinus torrei; dorsal view, USNM 157852, 285 mm TL (Cuba, 22°55’N, 79°27’W). A, external morphology; B, skeleton. crh, cover rhipidion; end, endstyle; en, envelope; erh, exorhipidion; hp, hipopyle; rd, dorsal marginal cartilage; 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 = 5 mm.

FIGURE 92. Map showing the geographic distribution of Scyliorhinus torrei based on the material examined in this study. Black star indicates the type locality.

Tables

TABLE 19. Morphometric and meristic data of Scyliorhinus torrei. SD, standard deviation; n, number of examined specimens. Total length (TL) in mm, other measurements as percentages of TL.

Characters	Holotype	n	Range	Mean	SD
Total length (TL)	250.0	39	113.7—294.3	241.2	30.5
Precaudal length	76.1	39	73.9–79.8	76.4	1.7
Eye-spiracle length	1.3	39	0.7–1.5	1.4	1.2
Prenasal length	3.4	39	2.3–3.8	2.8	0.4
Preoral length	5.0	39	3.9–11.3	4.7	0.5
Preorbital length	6.9	39	5.2–8.6	6.8	0.6
Prespiracular length	10.8	39	9.3–20.6	10.7	0.7
Prebranchial length	16.0	39	12.5–26.3	15.1	1.0
Head length	20.4	39	8.6–22.9	19.7	1.3
Prepectoral length	17.9	39	15.0–20.7	17.8	1.4
Prepelvic length	40.4	39	31.1–42.7	37.8	2.3
Snout-vent length	43.9	39	34.1–46.4	42.8	2.6
Vent-caudal length	56.9	36	49.1–60.4	55.8	3.4
Pre-first dorsal length	49.6	36	40.3–49.7	46.8	2.3
Interdorsal distance	11.0	39	8.5–13.9	11.0	1.3
Dorsal-caudal distance	5.4	39	3.4–7.5	5.4	0.9
Pectoral-pelvic distance	16.5	39	10.0–19.7	16.0	1.7
Pelvic-anal distance	11.1	39	8.7–14.0	11.5	1.3
Anal-caudal distance	8.1	39	5.5–19.8	8.0	1.1
Interorbital distance	7.5	39	6.5–9.0	7.5	0.6
Internarial distance	5.8	39	4.6–6.1	5.5	0.4
Mouth length	5.9	39	4.1–6.7	5.2	0.7
Mouth width	9.5	39	7.0–10.4	8.3	0.8
Lower labial furrow length	2.2	39	1.8–3.0	2.3	0.3
Eye length	4.0	39	2.9–4.4	3.9	0.3
Eye height	1.6	39	1.1–2.2	1.5	0.2
Spiracle length	1.0	39	0.6–1.3	0.9	0.1
First gill slit height	2.8	39	1.8–3.5	2.9	0.4
Fifth gill slit height	1.4	39	0.9–1.7	1.3	0.2
Pectoral length	14.1	39	10.3–14.3	12.2	0.9
Pectoral anterior margin	14.9	39	10.8–14.9	12.7	1.0
Pectoral base	7.4	39	4.7–7.5	6.0	0.6
Pectoral posterior margin	8.5	39	5.4–8.9	7.3	0.9
Pectoral inner margin	6.7	39	4.9–8.3	6.6	1.1
Pelvic length	11.6	39	9.1–14.6	11.9	1.8
Pelvic anterior margin	6.0	39	5.5–9.0	6.7	0.8
Pelvic posterior margin	6.4	36	4.7–8.7	7.0	1.0

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