Scyliorhinus hesperius Springer, 1966

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 : 70-78

Scyliorhinus hesperius Springer, 1966

( Figs. 49–55 , Tabs. 3 , 12, 13 )

Common names: whitesaddled catshark ( United States), roussette selle catshark ( France).

Scyliorhinus hesperius Springer, 1966: 603 –604, figs. 7d, 9a, 15b (original description, type locality: Panama); Springer, 1979: 137 –139, figs. 87-89 (taxonomic review); Compagno, 1984: 363 –364 (FAO catalogue); Compagno, 1999: 480 (listed); Compagno et al., 2005: 250 –251, pl. 42 (compilation); Castro, 2011: 338 –339, fig. 87a (catalogue, North America); Kyne et al., 2012: 58 (catalogue, Caribbean Sea); Ebert et al., 2013a: 374, 381, pl, 52 (compilation); Hacohen-Domené, Polanco-Vásquez & Graham, 2016: 1 –6 (occurrence record for Guatemala); Weigmann, 2016: 43 (listed).

Scyliorhinus retifer boa: Springer & Sadowsky, 1970: 90 –91 (only part referring to the holotype of S. hesperius [USNM 187732], specimen USNM 187728, and specimens captured in Honduras and Panama); Cadenat & Blache, 1981: 183 –184, fig. 125a (listed).

Holotype. USNM 188732 , female, 425 mm TL ( Caribbean coast of Panama, Gulf of Mosquitos, 9° 03’N 81°22’W, 366–402 m depth).

Additional material examined. 19 specimens (see Appendix).

Diagnosis. Scyliorhinus hesperius differs from all congeners by presenting a color pattern composed by spots beige or cream greater than spiracles (vs. light spots absent in S. cervigoni , S. garmani , S. meadi , and S. retifer ; light yellow to golden in S. capensis ; cream spots predominantly smaller in S. boa , S. cabofriensis , S. canicula , S. stellaris , and S. ugoi ); anterior nasal flaps not reaching the upper lip (vs. reaching the upper lip, and sometimes covering it, in S. canicula , S. cervigoni , S. comoroensis , S. duhamelii , S. garmani , and S. stellaris ); oral canal of lateral line system with 5–6 pores (vs. more than 7 pores in all other species); interdorsal space 1.0–1.5 times the anal base length (vs. smaller than the anal base in S. canicula , S. cervigoni , S. comoroensis , S. duhamelii , S. garmani , S. stellaris , and S. torazame ); pelvic apron extending to 2/3 of length of pelvic inner margins (vs. extending through almost the entire length in S. canicula , S. capensis , S. duhamelii , S. torazame , and S torrei ). The following combination of characters, although less conspicuous, also helps distinguish this species: saddles prominent and darker than the background (vs. saddles inconspicuous in S. cabofriensis , S. cervigoni , S. duhamelii , S. garmani , and S. torrei ); light spots when present between saddles, greater than spiracles and close together (vs. smaller than spiracles and sparse, more separated in S. comoroensis and S. haeckelii ); nasoral grooves absent and anterior nasal flaps situated on the posterior border of excurrent apertures (vs. grooves present and flaps situated laterally in S. canicula and S. duhamelii ); mandibular canal of lateral line system presenting 3 or 4 pores (vs. 5 or more in S. capensis , S. cervigoni , S. stellaris , S. torazame , and S. torrei ); commissural teeth with three cusplets (vs. two or less in other species, except in S. boa , S. canicula and S. capensis ); 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 entire length in S. canicula , S. capensis , S. duhamelii , S. torazame , and S. torrei ); clasper with terminal dermal cover smooth (vs. rough in S. canicula and S. capensis ); clasper envelope medially expanded (vs. poorly developed or absent in other species, except in S. boa and S. retifer ); cover rhipidion well-developed (vs. poorly developed in S. canicula and S. duhamelii ); cover rhipidion without dermal denticles (vs. present in other species, except S. boa , S. cervigoni and S. retifer ); distance between nasal apertures 17.9–21.6% NL (vs. 12.8–15.6% in S. boa ; 27.8–37.6% in S. canicula ; 27.6–29.8% in S. stellaris ); width across suborbital shelves 62.4–74.4% NL (vs. 67.9–71.5% in S. stellaris ); width across postorbital processes 63.3–70.6% (vs. 75.6–75.8% in S. boa ; 72.1–82% in S. capensis ; 75–90.8% in S. torazame ; 72.4–88.4% in S. torrei ); counts of monospondylous vertebrae 39–42 (vs. 44–46 in S. capensis ; 35–37 in S. duhamelii ; 48 in S. garmani ; 46–48 in S. meadi ; 43–47 in S. stellaris ; 32–37 in S. torazame ; 30–35 in S. torrei ); adult males at least 420 mm TL (vs. adult males greater than 450 mm TL in S. capensis , S. cervigoni , S. meadi , and S. stellaris ; adult males 269 mm TL in S. torrei ).

Description. Morphometric and meristic data are given in Table 12, and neurocranial measurements in Table 13 .

Body slender and cylindrical, tapering considerably posterior to cloaca ( Figs. 49 , 50 ). Prepectoral length 0.4 times the prepelvic length. Trunk shorter than tail; snout-vent length 0.8 times vent-caudal length. Pectoral-pelvic space 1.3–1.6 (1.6) times the pelvic-anal space. Interdorsal space 2.3–3.1 (2.4) times the dorsal-caudal space ( Tab. 12). No interdorsal, postdorsal or postanal ridges; lateral crest on caudal peduncle absent.

Head moderately broad and depressed; head length 1.5–1.6 (1.6) times head width ( Figs. 49 , 50 ). Snout relatively short, preoral length 0.5–0.6 (0.6) times mouth width and 1.3–1.6 (1.2) times smaller than preorbital length. Prenasal length 0.6–1.0 (0.5) times internarial space; preorbital length 0.5–1.0 (0.9) times interorbital space. Eye large and slitlike, eye length 2.7–3.4 (3.0) times its height and 0.2 times smaller than head length ( Figs. 49 , 50 ). 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 2.2–7.6 (4.5) times in eye length and 3.3–13.6 (9.1) 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. 51 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 1/4 of anterior nasal flap. Internarial space 1.4–1.6 (1.2) times smaller than interorbital space.

Mouth arched, wider than long, its length goes 1.8–2.0 (1.8) times in mouth width ( Figs. 51 A–B). Lower labial furrow short and narrow, 3.9–4.0 (4.1) 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. 52 ). Sexual heterodonty not observed; only adult females examined. Tooth counts 20–26 19–25/ 20–25 1 19 –25 (24–25/24–22). Parasymphysial teeth with a principal cusp flanked by one cusplet on each side; cusplets 1/3 the height of the principal cusp. Protuberances on medial portion of the crown base and striae from the crown base toward the apex of the principal cusp. Anterior teeth larger than the parasymphysial and principal cusp less stout. Anterior teeth with three to four cusplets; marginal cusplets, when present, poorly developed. Anterior upper teeth with proximal cusplets corresponding to half the height of the principal cusp; cusplets 1/3 the height of the principal cusp in lower teeth. Protuberances on the crown base and striae extending throughout the principal cusp. 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 and mesial marginal poorly developed. Principal cusp semioblique in both jaws. Protuberances on the crown base and striae extending throughout the crown. Commissural teeth with three cusplets; principal cusp stronger, semioblique and laterally situated. Mesial proximal cusplet slightly smaller and 2/3 the width of the principal cusp. Protuberances well prominent on the crown base 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 teardrop-shaped crowns, 1.7–1.9 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 presenting well-developed cusplets, 0.4 times the principal cusp; distinct lateral ridges. Cusplets poorly developed in posterior regions with short or reduced lateral ridges ( Fig. 53 ).

Pectoral base 0.9–1.0 (0.9) times mouth width ( Fig. 51C ). Pectoral anterior margin 1.7–2.0 (2.2) times its base and 1.6–1.8 (1.8) times the posterior margin. Pectoral fin skeleton aplesodic with radials mostly divided into three segments. Propterygium and mesopterygium trapezoids; the former smaller than the latter. Propterygium with one proximal segment; mesopterygium with 3–4 proximal segments fused proximally. Metapterygium with 8–9 segments. Metapterygial axis rectangular and corresponding to 1/5 of metapterygium.

Pelvic fin triangular ( Fig. 51F ); pelvic anterior margin 1.1–1.2 (1.1) times the posterior margins and 0.7–1.2 (0.9) times the pelvic base. Pelvic inner margins of males fused for 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 0.7–1.1 times the pelvic anterior margin, 1.3–3.1 times the clasper outer length and 4.5–9.0 times the clasper base. Most of clasper surface except dorsomedial surface of glans, envelope, cover rhipidion, rhipidion, and terminal dermal cover, covered by dermal denticles with anteriorly directed crowns ( Fig. 54 ). Clasper hooks absent. Rhipidion well-developed, partly covered medially by a prominent exorhipidion and anteriorly by the cover rhipidion. Cover rhipidion expanded medially reaching the exorhipidion and sometimes covered by this anteriorly; both cover rhipidion and exorhipidion covering the clasper groove. Envelope expanded medially and covering the anterior border of the cover rhipidion; pseudosiphon not observed. Terminal dermal cover extending for 1/3 of the ventral terminal cartilage, contacting the exorhipidion, and covering the cover rhipidion. Clasper skeleton not examined.

First dorsal fin triangular, sometimes square-tipped, with nearly straight anterior margin, rounded apex and angular free rear tip ( Figs. 49 , 50 ). First dorsal fin origin posterior to the insertion and above half of pelvic inner margins; males presenting first dorsal fin slightly posterior. First dorsal fin insertion opposite to the anterior 2/5 of pelvic-anal distance. Anterior margin 1.4–1.5 (1.6) times first dorsal fin base; first dorsal fin height 0.7–0.9 (0.8) times its base.

Second dorsal fin smaller than the first and triangular, sometimes subrectangular ( Figs. 49 , 50 ). Second dorsal fin origin slightly opposite to the posterior 1/3 of anal base and insertion posterior to the anal fin. Anterior margin 1.3–1.5 (1.5) times base of second dorsal fin; second dorsal base 1.0–1.5 (0.9) times its height and 1.1–1.6 (1.1) times the dorsal-caudal distance. First dorsal fin 1.1–1.2 (1.0) times larger than the second dorsal fin.

Anal fin triangular, apically narrow, not falcate and similar to second dorsal fin ( Figs. 49 , 50 ); anal fin base 1.6–1.7 (1.9) 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 (0.9) times the interdorsal distance and 2–2.3 (2.1) times the dorsal-caudal distance. Anal anterior margin 1.7–3.4 (1.9) times the posterior margin; anal fin height 0.4–0.5 (0.4) times its base.

Caudal fin narrow-lobed and asymmetrical ( Figs. 49 , 50 ). Dorsal caudal lobe 1.9–2.1 (2.1) times larger than preventral lobe; subterminal caudal margin 0.8–1.1 (1.1) times the terminal margin. Caudal crest of enlarged denticles absent on caudal fin margins.

Neurocranium broad and somewhat flattened, corresponding to 9.9–10.8% TL. Rostrum length similar to the distance between lateral rostral cartilages. Nasal capsule wider than long, oval-shaped and expanded laterally; width 0.9–1.2 times its length. Anterior fontanelle broad and heart-shaped in females (males not available for dissection); epiphyseal notch very prominent. Orbital region 2.2 times smaller than nasobasal length. Otic capsule short, its length 3.9–5.2 times smaller than nasobasal length and width 2.1–2.5 times otic capsule length. Width across postorbital processes 1.1–1.2 times the preorbital processes width ( Tab. 13 ).

Coloration in alcohol. Body beige with seven or eight saddles slightly darker than the background, interspaced by subsaddles on the sides; interdorsal saddle not prominent ( Fig. 50 ). Saddles delineated by light bands. Light spots greater than spiracles inside saddles, subsaddles and sometimes between saddles, not forming strictly parallel or bilaterally symmetric rows. Dark spots rare or absent. Specimen USNM 187688 presents light spots, greater than spiracles and close together, distributed all over dorsolateral surfaces, which are also present in the male specimens captured in Guatemala ( Hacohen-Domené et al. 2016; fig. 50B). Spots present on the proximal region of pectoral and dorsal fins; absent in pelvic and anal fins. Fins darker distally; body lighter on the lateral surface posterior to first dorsal fin and below lateral line. Belly and ventral surface of paired and anal fins without spots, cream in color.

Distribution. This species is endemic to the Western Central Atlantic, where it is known to occur on the continental shelves from Guatemala, Honduras, Nicaragua, Panama, and Colombia ( Fig. 55 ).

Biological data. Adult male measured 420 mm TL ( Hacohen-Domené et al. 2016). Adult female 470 mm TL ( Compagno 2002; Compagno et al. 2005; Kyne et al. 2012); largest female examined 425 mm TL. This species is a benthic dweller in water depths of 200– 634 m. Of no interest to fisheries at present, and adults (especially males) may occupy habitats unfavorable to trawling. Conservation status ‘Data Deficient’ (Leandro 2004).

Remarks. Springer & Sadowsky (1970) considered S. hesperius a junior synonym of S. boa , referring to it as the ‘white-spotted form’. The authors related that the white spots become more prominent with growth in S. boa , using this character to distinguish it from S. haeckelii , in which the spots would disappear. Soares et al. (2016) reported some adult specimens of S. haeckelii with white spots (predominantly found in males) contradicting Springer & Sadowsky (1970). Later, Springer (1979) resurrected S. hesperius with no further explanation and was followed by subsequent authors. Specimen USNM 187728, previously identified as S. retifer boa by Springer & Sadowsky (1970), is reidentified here as S. hesperius .

Recently, five adult males were captured in a depth of 200 m from the Caribbean coast of Guatemala ( Hacohen-Domené et al. 2016). These specimens represent the first (and unique until now) records of mature males of S. hesperius , as well for this species in Guatemalan territorial waters. Morphometric data of these specimens as well the photographs published by Hacohen-Domené et al. (2016) were analyzed here. Photographs sent by José Ortiz (USAC) were used for the examination and description of clasper external morphology.

Figures

FIGURE 49. Holotype of Scyliorhinus hesperius Springer, 1966, USNM 187732, female, 425 mm TL (Caribbean coast of Panama, Gulf of Mosquitos, 9° 03’N 81°22’W). A, dorsal view; B, lateral view. Scale bar = 20 mm.

FIGURE 50. Scyliorhinus hesperius; lateral view. A, CAS 643, female, 265 mm TL (Caribbean Sea, 12°35’N, 82°19’W); B, USNM 187688, female, 316 mm TL (Caribbean Sea, 16°45’N, 81° 27’W). Scale bar = 20 mm.

FIGURE 51. Scyliorhinus hesperius. A, D, E, USNM 187732, female, 425 mm TL (Caribbean coast of Panama, Gulf of Mosquitos, 9° 03’N 81°22’W); B, USAC 256, male, 420 mm TL (Izabal, Guatemala, 15° 49.78’N, 88°12.34’W); C, USAC 254, male, 429 mm TL (Izabal, Guatemala, 15° 49.78’N, 88°12.34’W); F, USNM 187728, female, 338 mm TL (Nicaragua, 14°10’N, 81°55’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 52. Teeth of Scyliorhinus hesperius; labial view, USNM 187688, female, 316 mm TL (Caribbean Sea, 16°45’N, 81° 27’W). a, anterior tooth; c, commissural; l, lateral; ps, parassymphysial. Scale bar = 100 µm.

FIGURE 53. Dermal denticles of Scyliorhinus hesperius, USNM 187688, female, 288 mm TL (Caribbean Sea, 16°45’N, 81° 27’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 54. Clasper of Scyliorhinus hesperius: dorsal view, USAC 254, 429 mm TL (Izabal, Guatemala, 15° 49.78’N, 88°12.34’W). crh, cover rhipidion; erh, exorhipidion; hp, hipopyle; rh, rhipidion; tdc, terminal dermal cover. Scale bar = 20 mm.

FIGURE 55. Map showing the geographic distribution of Scyliorhinus hesperius based on material examined in this study. Black star indicates the type locality.

Tables

TABLE 12. Morphometric and meristic data of Scyliorhinus hesperius. 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)	425	16	178.4–474.0	319.7	53.4
Precaudal length	78.4	16	72.9–78.8	75.7	1.6
Eye-spiracle length	0.6	16	0.8–1.5	1.1	0.3
Prenasal length	2.8	16	2.6–3.9	3.1	0.4
Preoral length	5.1	16	4.9–6.1	5.3	0.4
Preorbital length	6.6	16	6.2–8.2	7.4	0.6
Prespiracular length	10.6	16	10.6–12.9	11.4	0.6
Prebranchial length	15.5	16	13.3–17.2	16.3	0.8
Head length	20.9	16	19.3–22.5	21.1	0.9
Prepectoral length	18.6	16	15.9–20.2	19.1	1.3
Prepelvic length	45.9	16	38.3–45.9	42.1	2.1
Snout-vent length	48.7	16	39.6–47.1	43.9	2.2
Vent-caudal length	58.4	16	51.0–58.5	56.0	3.7
Pre-first dorsal length	53.4	16	44.9–52.8	49.0	2.2
Interdorsal distance	10.1	16	9.4–13.0	10.7	1.0
Dorsal-caudal distance	4.3	15	3.0–5.7	4.8	0.8
Pectoral-pelvic distance	16.2	15	14.1–19.2	12.1	1.3
Pelvic-anal distance	10.2	16	8.5–14.9	11.0	1.1
Anal-caudal distance	5.8	16	6.3–8.5	7.5	1.0
Interorbital distance	7.3	16	6.8–8.1	7.7	0.3
Internarial distance	5.8	16	4.3–5.9	5.9	0.4
Mouth length	4.5	16	3.4–5.5	.2	0.8
Mouth width	8.3	16	6.9–9.7	8.3	1.0
Lower labial furrow length	2.0	16	1.7–2.5	2.1	0.2
Eye length	3.6	16	3.8–5.4	4.0	0.3
Eye height	1.2	16	1.1–2.0	1.7	0.2
Spiracle length	0.8	16	0.5–2.4	0.9	0.2
First gill slit height	2.4	16	2.1–3.4	2.7	0.4
Fifth gill slit height	1.3	16	1.2–1.7	1.5	0.2
Pectoral length	13.7	16	11.7–15.4	13.8	0.9
Pectoral anterior margin	16.3	16	12.3–16.5	15.4	0.9
Pectoral base	7.4	16	6.2–9.5	6.6	0.9
Pectoral posterior margin	8.8	16	7.9–10.4	9.2	1.2
Pectoral inner margin	7.2	16	5.8–7.8	6.6	0.4
Pelvic length	10.8	16	9.2–11.7	10.9	0.5
Pelvic anterior margin	6.5	16	5.9–7.9	7.2	0.5
Pelvic posterior margin	6.1	16	4.9–7.3	6.1	0.5
Pelvic base	7.0	16	5.0–10.5	7.5	0.5
Pelvic inner length	3.9	16	3.1–5.4	3.7	0.4
Clasper outer length	–	6	1.3–4.7	1.9	0.7
Clasper inner length	–	5	4.0–6.3	4.3	0.2

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