Scyliorhinus canicula ( Linnaeus, 1758 )

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 : 20-32

Scyliorhinus canicula ( Linnaeus, 1758)

( Figs. 12–18 , 19A ; Tabs. 3–5 )

Common names: Lesser spotted dogfish, Smaller spotted dogfish, Small-spotted dogfish, Spotted dogfish, Dogfish, Nurse, Sandy dog, Robin huss, Suss, Land dog, Row hound, Cur fish, Kennet, Daggar (English); Morgay, Blin e es ( Scotland); Daw fish (Orkneys); Morghi meiaf ( Wales); Squale roussette, La rousette a petites taches, Petit rousette, Charon, Charotel, Chat marin, Cata roussa, Pintou roussou, Rousse ( France); Katzenai, Kleiner Katzenhai ( Germany); Hondshaai ( the Netherlands); Zee hond ( Belgium); Småplettet rødhaj ( Denmark); Deplaháfur ( Iceland); Cat, Gat, Gatet, Gat vaire, Pinta rotja, Pintarrosa, Pintarroja ( Spain); Pata roxa, Pintarroxa ( Portugal); Dogfish, Sandy dogfish (Azores); Småfläckig rödhaj ( Sweden); Morskoy pes ( Russia).

Squalus canicula Linnaeus, 1758: 234 (original description, type locality: Mediterranean Sea); Houttuin, 1764: 505 (compilation); Linnaeus, 1766: 399 (compilation); Berkenhout, 1769: 36 (catalogue, Great Britain and Ireland); Heppe, 1787: 212 (compilation); Bonnaterre, 1788: 6 (compilation); Bloch, 1796: 798 –802 (compilation); Duperrey, 1830: 83 (catalogue, survey ‘La Coquille’); Lacépède, 1830: 373–384 (compilation).

Squalus catulus Linnaeus, 1758: 235 (original description, type locality: Mediterranean Sea); Houttuin, 1764: 505 –508 (compilation); Linnaeus, 1766: 400 (compilation); Bloch, 1796: 805 –807 (compilation) [synonymy follows Compagno, 1984: 358 –359].

Scyliorhinus caniculus Blainville, 1816: 121 (listed, classification).

Scyllium canicula: Cuvier, 1817: 124 (compilation); Cuvier, 1829: 386 (compilation); Cuvier et al., 1834: 586 (catalogue, classification); Jenyns, 1835: 495 –496 (catalogue, United Kingdom); Partington, 1837: 651 (compilation); Parnell, 1838: 407 –409 (catalogue, North Sea); Schinz, 1840: 460 –461 (catalogue, Europe); Müller & Henle, 1838 –41: 6–7, pl. 7 (catalogue, systematics of Elasmobranchii); Hamilton, 1854: 300 (compilation); Duméril, 1865: 315 –316 (compilation); Bocage & Capello, 1866: 11 (catalogue, Portugal); Günther, 1870: 402 (catalogue, British Museum); Canestrini, 1872: 50 (catalogue, Italy); Collett, 1875: 210 (compilation); Doderlein, 1880: 24–26 (catalogue, Mediterranean Sea); Balfour, 1881: 656 –671 (anatomy and ontogeny of paired fins); Bolau, 1881: 321–325 (reproductive biology); Doderlein, 1881: 24 (catalogue, Mediterranean Sea); Moreau, 1881: 278 –280, figs. 34, 35 (catalogue, France); Faber, 1883: 181 (catalogue, Adriatic Gulf); Day, 1884: 309–312, fig. 1, pl. 159 (catalogue, Great Britain and Ireland); Jungersen, 1899: 32 –34, figs. 16, 17 (clasper description); Gordon, 1902: 135 (catalogue, Great Britain); Coward, 1910: 160 (catalogue, Cheschire and Liverpool Bay); Leigh-Sharpe, 1920: 252 –259, figs. 2–7 (description and clasper ontogeny).

Squalus elegans Blainville, 1825: 73 , fig. 1, pl. 18 (listed, classification) [synonymy follows Compagno 1984: 358].

Scyllium caniculus: Risso, 1826: 116 (catalogue, Meridional Europe).

Scyllium catulus: Fleming, 1828: 165 (catalogue, United Kingdom); Smith, 1833: 81 –82 (catalogue, Massachussetts); Couch, 1868: 14 –17 (catalogue, British Islands).

? Scyllium acutidens Vaillant, 1888:60 (original description, type locality: Eastern Atlantic).

Scylliorhinus canicula: Hoffman & Jordan, 1892 : 233; (catalogue, Greece); Collett, 1905: 9 (compilation); Danois, 1913: 14 –15, figs. 3, 6, 7 (compilation); Lozano Rey, 1928: 306, pl. 2, figs. 1, 86, 87 (catalogue, Iberian Peninsula); Maurin & Bonnet, 1970: 129 (catalogue, Northwestern Africa).

Scyliorhinus canicula var. albomaculata Piestchmann, 1906: 98 (original description, type locality: west coast of Morocco, Mediterranean Sea).

Catulus caniculus: Garman, 1913: 72 –73 (brief account).

Catulus duhamelii Garman, 1913: 73 –74 (original description, type locality: Adriatic Sea; incorrect identification of the female specimen, MCZ 60–S).

Scyllium (Alphascyllium) canicula Leigh-Sharpe, 1924: 322 (classification based on clasper morphology).

Haploblepharus caniculus: White, 1937: 121 (systematics, listed).

Scyliorhinus caniculus: Bigelow & Schroeder, 1948: 203 (catalogue, compared with Northwestern Atlantic species).

Scyliorhinus canicula: Regan, 1908: 458 (classification, listed); Ford, 1921: 486 –492 (reproductive biology and diet); Brough, 1937: 217 –273 (sexual dimorphism); Leloup & Olivereau, 1951: 182 –209 (morphometrics); Tortonese, 1956: 127, figs. 62–65 (catalogue, Italy); Wheeler, 1969: 45, figs. 13, 14 (catalogue, British Islands); Springer, 1973: 19 (catalogue, Northwestern Atlantic and Mediterranean Sea); Capapé, 1977: 83 –101 (reproductive biology); Springer, 1979: 129 –132, fig. 83 (taxonomic review); Cadenat & Blache, 1981: 177 –178 (except part referring to specimens collected at Senegal); Lyle, 1983: 725 –733 (diet); Compagno, 1984: 358 –359 (FAO catalogue); Feng & Knight, 1994: 285 –302 (egg capsules); Ellis & Shackley, 1995: 361 –372 (reproductive biology); Rodríguez-Cabello et al., 1997: 363 –370 (age and growth); Rodríguez-Cabello et al., 1998: 187 –191 (reproductive biology); Compagno, 1999: 480 (listed); Fricke, 1999: 15 –16 (listed); Henderson & Casey, 2001: 397 –405 (reproductive biology); Sims et al., 2001: 1165 –1175 (reproductive biology); Litvinov, 2003: 81–86 (reproductive biology); Capapé et al., 2004: 21 –22 (catalogue, Tunisia); Erdogan et al., 2004: 165 –170 (sexual dimorphism); Compagno et al., 2005: 247 –248, pl. 41 (compilation); Serena, 2005: 38, pl. IV, 30 (FAO catalogue, Mediterranean Sea); Ellis et al., 2005: 199 (sexual dimorphism); Ivory et al., 2004: 89 –106 (age, growth and reproduction); Filiz & Taskavak, 2006: 37 –47 (sexual dimorphism); Rodríguez-Cabello et al., 2007: 1568 –1586 (sexual dimorphism); Capapé et al., 2008: 282 –289 (reproductive biology); Kimber et al., 2009: 1 –6 (populational study); Crooks et al., 2013: 1 –7 (sexual dimorphism); Ebert et al., 2013a: 372, 378, pl. 51 (compilation); Ebert & Stehmann, 2013: 207 –209, figs. 238, 239 (egg capsules); Lynghammar et al., 2013: 60 (phylogeographic study); Bilecenoglu et al., 2014: 904 (catalogue, Turkey); Kousteni et al., 2014: 1 –11 (phylogeographic study); Dyldin, 2015: 50 (catalogue, Russia); Gordon et al., 2016: 272, fig. 8b (egg capsules); Weigmann, 2016: 43 (listed).

Neotype. NHMUK 1866.9 .12.4, male, 417.1 mm TL ( Nice , France). [designated herein].

Additional material examined. 312 specimens (see Appendix).

Diagnosis. Scyliorhinus canicula differs from all congeners by presenting shallow nasoral grooves and laterally situated posterior nasal flaps (vs. grooves absent and posterior flaps situated on the posterior border of the excurrent apertures in congeners, except in S. duhamelii ); distance between the anterior nasal flaps 6–7.5 times smaller than the anterior nasal flap width (vs. 3.5–5 times smaller in S. duhamelii ; two times in the other species); lower labial furrow 2.1–2.2 times smaller than mouth width (vs. more than three times in other species, except S. duhamelii ); color pattern with dark spots well defined and predominantly smaller than spiracles (vs. dark spots absent in S. capensis , S. comoroensis , S. hesperius , S. meadi , S. torazame , and S. torrei ; reticulated pattern in S. retifer ; dark spots predominantly larger than spiracles in S. cervigoni , S. garmani , S. haeckelii , and S. stellaris ; diffuse spots in S. duhamelii ); clasper with rough terminal dermal cover (condition also found only in S. capensis ). The following combination of characters, although less conspicuous, also helps distinguish this species: anterior nasal flaps covering the upper lip (vs. not covering the upper lip in congeners, except S. cervigoni , S. comoroensis , S. duhamelii , S. garmani , and S. stellaris ); spots spread on entire dorsolateral surface (vs. spots restricted to the saddles in S. boa , S. cervigoni and S. haeckelii ); oral canal of lateral line system with 8–10 pores (vs. 5–6 in S. hesperius ; 10–12 in S. duhamelii ; 9–13 in S. torrei ); commissural teeth presenting three or four cusplets (vs. two or less in the other species, except in S. boa , S. capensis and S. hesperius ); interdorsal space 0.6–1.0 times the anal base (vs. larger than the anal base in S. boa , S. cabofriensis , S. haeckelii , S. hesperius , S. meadi , S. retifer , S. torrei , and S. ugoi ); pelvic fins triangular (vs. subrectangular in S. garmani , S. stellaris and S. torazame ); males with pelvic apron extending through almost the entire length of the pelvic inner margins (vs. extending to only 2/ 3 in the other species, except in S. capensis , S. duhamelii , S. torazame , and S. torrei ); terminal 3 cartilage present (vs. absent in S. cabofriensis , S. cervigoni , S. comoroensis , S. duhamelii , S. haeckelii , S. stellaris , S. torrei , and S. ugoi ); 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 ; corresponding to 1/ 3 in S. boa and S. comoroensis ; same length of dorsal terminal cartilage in S. torazame ); neurocranium with basal plate width 58.2–65.1% NL (vs. 68.2–69.3% in S. boa ; 65.8–75.3% in S. capensis ; 71.9–82.6% in S. torazame ; 67.4–69.5% in S. torrei ); distance between nasal apertures 27.8–37.6% NL (vs. 12.8–15.6% in S. boa ; 20.1–26.9% in S. capensis ; 17.9–21.6% in S. hesperius ; 13.9–25.6% in S. retifer ; 15.0–18.3% in S. torrei ); optic capsules width less than two times their length (vs. 2.7–2.8 times in S. boa , S. capensis , S. hesperius , S. meadi , and S. stellaris ); upper teeth 40–61 (vs. 33–42 in S. torrei ); lower teeth 36–50 (vs. 48–85 in S. capensis ); counts of monospondylous vertebrae 34–40 (vs. 44–46 in S. capensis ; 40–45 in S. cervigoni ; 48 in S. garmani ; 46–48 in S. meadi ; 43–47 in S. stellaris ); adult males between 370–520 mm TL and adult females between 370–560 mm TL (vs. 269 mm and 294 mm in S. torrei , respectively; greater than 600 mm TL in S. capensis , S. cervigoni and S. stellaris ).

Description. Morphometric and meristic data are given in Table 4 , and neurocranial measurements in Table 5 .

Body slender and cylindrical, tapering considerably posterior to cloaca ( Figs. 12 , 13 ). Prepectoral length 0.4–0.5 (0.4) times the prepelvic length. Trunk shorter than tail; snout-vent length 0.8–0.9 (0.8) times vent-caudal length. Pectoral-pelvic space 1.4–1.7 (1.6) times the pelvic-anal space. Interdorsal space 1.8–3 (2.4) times the dorsal-caudal space ( Tab. 4 ). No interdorsal, postdorsal or postanal ridges; lateral crest on caudal peduncle absent.

Head moderately broad and depressed; head length 1.7–2.6 (1.9) times head width ( Figs. 12 , 13 ). Snout relatively short, preoral length 0.8–0.9 times mouth width and 0.6–0.8 (0.8) times smaller than preorbital length. Prenasal length 0.6–0.8 (0.8) times internarial space; preorbital length 07–0 8 times interorbital space.

Eye large and slitlike, eye length 1.7–2 (1.9) times its height and 0.2 times smaller than head length ( Figs. 12 , 13 , 14 D–E). 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 eye, dorsolaterally on head and somewhat lower than level of eye notch. Spiracle diameter goes 3.8–6.2 (5.3) times in eye length and 5.6–6.7 (6.1) 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 nasal barbel, and small and oval excurrent aperture; shallow nasoral groove present. Anterior nasal flap large and triangular, covering the posterior nasal flap, excurrent aperture and upper lip; distance between anterior nasal flaps 6–7.5 (7.2) times in nasal flap width ( Figs. 14 A–B). Mesonarial ridge poorly developed and not exceeding the posterior border of the anterior nasal flap. Posterior nasal flap elongated and rodlike, tapering toward the posterior edge and situated on the lateral edge of the excurrent aperture and corresponding to 1/3 of the nasal flap. Mesonarial superior and inferior flaps triangular and corresponding to 1/ 3 of anterior nasal flap. Internarial distance 1.3–1.5 (1.5) times smaller than interorbital distance.

Mouth arched and moderately short, its length goes 1.3–1.4 (1.4) times in mouth width ( Figs. 14 A–B). Lower labial furrow long and narrow, 2.1–2.2 (2.1) times mouth width. Dorsal labial cartilage 1.3 times the ventral labial 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 greater than the parasymphysial ones and lateral teeth smaller distally, with smaller and thicker principal cusps ( Fig. 15 ). Sexual heterodonty well pronounced with females presenting more cusplets in parasymphysial, anterior and lateral teeth (4) and principal cusp shorter in relation to males. Tooth counts 20–31 0–1 20–30/ 18–28 1 19 –28 (22–25/19–22). Parasymphysial teeth with a principal cusp flanked by one or two cusplets on each side; proximal cusplets 2/3 the height of principal cusp and marginal cusplets poorly developed. Protuberances on the crown base or striae absent. Anterior teeth with the same number of cusplets and greater and distally narrow principal cusp in relation to parasymphysial teeth. Females with anterior upper teeth presenting proximal cusplets half the height of the principal cusp and marginal cusplets corresponding to 2/3 of proximal cusplets; marginal cusplets half the height of proximal cusplets on lower teeth. Males with upper and lower anterior teeth with a strong principal cusp and cusplets poorly developed or absent. Striae absent from anterior lower teeth and extending almost through the entire length of crown on upper teeth. Lateral teeth with similar shape and slightly smaller than the anterior teeth. Protuberances on the crown base and striae running from the base toward the apex of the crown in both jaws. Lateral upper teeth with slightly oblique principal cusp; straight principal cusp on lower teeth. Commissural upper teeth with three cusplets; principal cusp stronger, slightly oblique and in a more lateral position in the crown. Mesial proximal cusplet with similar length and width corresponding to 2/3 of the principal cusp. Mesial marginal and distal cusplets slightly smaller than the mesial proximal one. Commissural lower teeth with four cusplets; principal cusp semioblique, similar length and as strong as the proximal cusplets. Marginal cusplets slightly smaller than the proximal ones. Protuberances present and striae running from the base toward the apex of crown on labial surface. Ectodermal pits present on lateral and commissural teeth, restricted to the crown base.

Lateral trunk denticles with flat, elongated teardrop-shaped crowns, 1.3–2.4 times longer than wide ( Tab. 3 ); anterior part covered with ectodermal pits. Dermal denticles above the pectoral fin with four cusplets, median ridge less prominent than in denticles at other regions and cusplets not extending to the angle between principal cusp and cusplets. Dermal denticles below the dorsal fins longer and presenting median and lateral ridges prominent, extending to the distal tip of cusplets; crown base slightly projected with 1–2 ridges reduced and medial to lateral ridges. Marginal ridges present in denticles of all regions ( Fig. 16 ).

Pectoral base 1.1–1.7 (1.4) times mouth width ( Fig. 14C ). Pectoral anterior margin 2.1–3.2 (2.4) times its base and 1.5–2.3 (2.1) 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 8–10 proximal segments. Metapterygial axis rectangular and corresponding to 1/4 of metapterygium.

Pelvic fin triangular ( Figs. 14 F–G); pelvic anterior margin 0.9 times the posterior margin and 1.0–1.1 (1.0) times the pelvic base; posterior and inner margins longer in adult males. Pelvic inner margins of males fused by almost all their extension, with sharp edges; claspers of juveniles covered by the pelvic apron and evident only with lifted apron.

Clasper short and cylindrical, sometimes extending beyond free rear tips of pelvic fins ( Fig. 14G ); clasper inner length 1.1–1.3 (1.3) times the pelvic anterior margin, 1.5–2.7 (2.3) times the outer length and 3.1–5.0 (4.6) times the clasper base. Most of clasper surface except dorsomedial surface of glans, mesial edge of cover rhipidion, rhipidion, and terminal dermal cover, covered by dermal denticles with anteriorly directed crowns ( Fig. 17A ). Clasper hooks absent. Rhipidion poorly developed and extending to the hindquarter of clasper; insertion of rhipidion at the anterior portion of dorsal terminal 2 cartilage. Cover rhipidion poorly developed and with straight edge, reaching medially and slightly anterior to exorhipidion. Envelope absent; pseudosiphon inconspicuous. Terminal dermal cover rough and slightly projected posteriorly, restricted to the clasper tip and reaching the distal portion of exorhipidion and cover rhipidion.

Clasper skeleton relatively simple ( Fig. 17B ). Ventral marginal cartilage shorter than the dorsal one; ventral terminal beginning anteriorly, but ending together with the dorsal terminal. Terminal 3 cartilage present, rodlike and situated between the terminal cartilages, and slightly smaller than the dorsal terminal 2 cartilage. Dorsal terminal 2 cartilage elongated and rod-like, laterally positioned on the dorsal terminal cartilage and at the same level of terminal 3 cartilage; it corresponds to 1/3 of the length of dorsal terminal cartilage. Ventral terminal 2 cartilage with same shape, although stronger than the terminal 3 and dorsal terminal 2 cartilages and corresponding to one half length of ventral terminal cartilage; beginning posteriorly to dorsal terminal 2.

First dorsal fin triangular, with nearly straight anterior margin, rounded apex and angular free rear tip ( Figs. 12 , 13 ). First dorsal fin origin above the anterior third or half of inner margin of pelvic fin; insertion above or slightly posterior to the anterior third of pelvic-anal distance. Anterior margin 1.3–1.6 (1.4) times first dorsal fin base; first dorsal fin height 0.7–0.8 (0.8) times its base.

Second dorsal fin smaller than the first and triangular ( Figs. 12 , 13 ). Second dorsal fin origin slightly above the hindquarter of anal base or opposite to the anal fin insertion. Anterior margin 1.2–1.6 (1.5) times base of second dorsal fin; second dorsal base 1.7 times its height and 0.9 times the dorsal-caudal distance. First dorsal fin 1.4 times larger than the second dorsal fin.

Anal fin low, apically narrow and not falcate ( Figs. 12 , 13 ); anal fin base 2.0–2.1 (2.1) 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 0.9–1.3 (1.2) times the interdorsal distance and 2.3 times the dorsal-caudal distance. Anal anterior margin 1.1–1.2 (1.1) times the posterior margin; anal fin height 0.3–0.5 (0.5) times its base.

Caudal fin narrow-lobed and asymmetrical ( Figs. 12 , 13 ). Dorsal caudal lobe 1.2–1.3 (1.3) times the preventral lobe; subterminal caudal margin 1.1–1.2 (1.1) times the terminal margin. Caudal crest of enlarged denticles absent on caudal fin margins.

Neurocranium broad and somewhat flattened, corresponding to 7.6–9.2% TL. Rostrum length 1.3–1.5 times the distance between lateral rostral cartilages. Nasal capsule as long as wide, oval-shaped and expanded laterally. Distance between nasal apertures proportionately smaller in males (27.8–28.2% NL) than in females (29.0–37.6% NL). Anterior fontanelle proportionately larger in females (20.7–22.6% NL) than in males (18.0% NL); epiphyseal notch very prominent. Orbital region corresponding to 2–2.3 times in the nasobasal length. Otic capsule width 1.6—1.9 times greater than its length. Width across postorbital processes 1.1–1.3 times the preorbital processes width ( Tab. 5 ).

Coloration in alcohol. Body beige to cream with seven or eight saddles, darker than the background ( Figs. 12 , 13 ). Dark spots of varied sizes throughout the entire dorsolateral surface; tiny spots on the head region anterior to spiracles, becoming greater posteriorly Spots greater on lateral surfaces, posterior to pelvic fins and below the lateral line; present on all fins, except anal. Some individuals present lunate spots, without aggregations of spots on the back or sides. Light spots, when present, greater than spiracles. Dorsal longitudinal stripe usually present, darker than the background color, extending from the spiracle level to the caudal peduncle. Presence of subsaddles between saddles anterior to the first dorsal fin. Distal edge of fins pinkish, mainly the paired fins. Males sometimes more pigmented than females. No regional differences in color pattern. Belly and ventral surface of paired fins without spots, uniformly cream.

Distribution. This species is widely distributed, extending from the North Sea (southwestern coast of Sweden to Copenhagen, Denmark), Northeastern Atlantic Ocean (continental shelves of Ireland, United Kingdom, France and Portugal), Mediterranean Sea (continental shelves of Spain, France, Italy, Tunisia, Argelia and Morocco) and northwestern Africa, close to the Strait of Gibraltar and to the north of Mauritania (20°30’N). Records exist from the Norwegian Sea ( Gratzianov 1907; Serena 2005; Ebert & Stehmann 2013; Lynghammar et al. 2013); specimens not examined here. Single record from the coast of Murman, Russia, in the Barents Sea ( Gratzianov 1907); according to Dyldin (2015), specimens have not been captured in this region since then, and therefore, this locality is not included in the geographic range of S. canicula ( Fig. 18 ).

Biological data. Adult males at 520–560 mm TL in the North Atlantic and between 370–400 mm TL in the Mediterranean Sea. Adult females between 540–600 mm TL in the North Atlantic and between 370–470 mm TL in the Mediterranean Sea; mean length for the egg deposition, 570 mm TL in the first region, and 410 mm TL in the Mediterranean Sea ( Ford 1921; Capapé 1977; Capapé et al. 1991; Ellis & Shackley 1997; Rodríguez-Cabello et al. 1998; Ivory et al. 2004). Largest examined female 719 mm TL; male 650 mm TL. Maximum size recorded, 1000 mm TL ( Compagno 1984) may be a result of misidentification with S. stellaris ( Ebert & Stehmann 2013) ; specimens exceeding 800 mm TL rarely observed ( Rodríguez-Cabello et al. 1998). Males with narrower heads and mouths and shorter intermandibular space than females ( Erdogan et al. 2004; Filiz & Taskavak 2006).

Females can store sperm for long periods, making long periods of oviposition possible ( Sumpter et al. 1978). Oviposition occurs throughout the year in the Languedocian coast, except in September, with peaks in April and August ( Capapé et al. 2008). In British waters, it happens mostly in the spring with a gap between August and October, peaks in June and July ( Ford 1921; Ellis & Shackley 1997). Oviposition occurs throughout the year in the Mediterranean Sea ( Kousteni et al. 2014). Egg capsules amber colored, with golden filaments ( Fig. 19A ). Anterior border nearly straight and posterior one slightly concave; posterior tendrils not crossed. Longitudinal striae present on the walls. Egg capsules vary in size according to location and size of female. Egg capsules are generally anchored on macroalgae or sessile invertebrates and found in large quantities, forming ‘nests’ (Ebert & Stehman 2013; Gordon et al. 2016).

This species inhabits preferably sandy and muddy substrates ( Compagno 1984) and is captured in depths between 10–400 m ( Ebert & Stehmann 2013). It is considered a generalist species and a demersal opportunistic macropredator, consuming a wide range of invertebrates and fishes ( Ford 1921; Lyle 1983); food preference reflects general abundance and availability of prey in the environment ( Lyle 1983). Among the organisms identified in stomach contents, there are decapods ( Carcinus, Liocarcinus and Palaemon ), hermit crabs ( Eupagurus bernhardus ), shrimp ( Upogebia stellata and Macropipus pusillus ), polychaetas ( Aphrodita spp.), mollusks ( Buccinum undatum, Glycymeris glycymeris) and holothurians ( Thyone spp.). Small crustaceans and polychaetas frequently found in juvenile specimens; teleosts and cephalopods become more important during stages of intense growth ( Lyle 1983).

Sims et al. (2001) described a sexual and space/temporal segregation pattern and different behavioral strategies of males and females of S. canicula . Females spend more time in shallow waters, under rocks or inside caves, and carrying out raids to deeper waters at night, while males do not take refuge in caves during the day and occupy warmer and distinct areas from females. Foraging behavior of males and females alters when individuals get in touch with the opposite sex ( Kimber et al. 2009). Besides that, some studies reported the philopatric behavior of this species, with individuals marked and recaptured in relatively close localities (<24 km) ( Rodriguez-Cabello et al. 1998).

Although S. canicula is listed as ‘Least Concern’ ( Ellis et al. 2009), it has been considered overexploited in studies of fish stocks ( Cardinale & Osio 2013). Furthermore, there are records of depletion of populations for some areas ( Gibson et al. 2006). This species has moderate commercial importance, and is primarily captured by trawls in several demersal fisheries and retained for human consumption, oil extraction and fish baits ( Springer 1979; Compagno 1984).

Remarks. According to Linnaeus (1758), Squalus canicula (= Scyliorhinus canicula ) differs from Squalus catulus by the configuration of pelvic fins, fused in the former and separated in the latter. Several subsequent authors followed this proposal until Jenyns (1853), who pointed out that those differences were, in fact, a secondary sexual dimorphism for S. canicula . Males of all species of Scyliorhinus present the pelvic inner margins fused and this fusion is referred here as the ‘pelvic apron’, being more extensive in S. canicula , S. capensis , S. duhamelii , S. torazame , and S. torrei .

The designation of a neotype for S. canicula , proposed by Fricke (1999), was invalidated because he contradicted articles 75.2 and 75.3 of the International Code for Zoological Nomenclature ( Motomura 2001). Fricke (1999) justified the need of a neotype for the species aiming to stabilize its status and distinguish it unequivocally from S. stellaris . However, the author did not review the taxonomy of S. canicula neither did he provide a diagnosis or any reasoning of his designation. Here, we provide a diagnosis and redescription of this species and designate a 417 mm TL adult male collected in the Mediterranean Sea as the neotype. We believe that this designation will contribute to reduce the misidentifications among S. canicula and other species with overlapping ranges ( S. cervigoni , S. duhamelii and S. stellaris ) and also help to distinguish this species from the newly revalidated species, S. duhamelii .

Scyllium acutidens Vaillant, 1888 is considered a questionable synonym of Scyliorhinus canicula by Van der Laan et al. (2014). The examination of the type specimens (MNHN 1884–0384, 1884–0385) was not possible as none of them were found. Vaillant (1888) reported the poor state of conservation of the two specimens, and did not describe the morphology of their nasal flaps and mouth, nor their color pattern. Therefore, this species is considered here a nomen dubium for S. canicula .

Scyliorhinus canicula presents a wide distribution range and its intraspecific variation and identity of populations has been discussed in many studies ( Leloup & Olivereau 1951; Rodríguez-Cabello et al. 1997; Ellis & Shackley 1997; Litvnov 2003; Rodríguez-Cabello et al. 2004; Barbieri et al. 2014; Kousteni et al. 2014). Barbieri et al. (2014) and Kousteni et al. (2014), analyzing molecular data and performing different sampling schemes, concluded that populations of S. canicula from the Adriatic and Ionian seas are genetically different from populations from other regions of the Mediterranean Sea. These results may be related to the presence of specimens of both S. canicula and S. duhamelii in their samples, considering the overall morphological similarity of both species and the geographic distribution of S. duhamelii .

Litivnov (2003) reported the presence of sexual heterodonty in individuals of S. canicula from off northwestern Africa, in which males presented poorly developed cusplets and females had narrower teeth with more cusplets. Litvinov (2003) suggested the existence of a new species distinct from S. canicula in northwestern Africa, based on the lack of information on sexual heterodonty in other populations of S. canicula ( Springer 1979; Herman et al. 1990; Compagno et al. 2005; Ebert et al. 2013a) and the absence of records between 34°N and the Strait of Gibraltar. However, sexual heterodonty was also observed in populations of S. canicula in the Mediterranean Sea and Northeastern Atlantic.

Specimens collected in northwestern Africa present a color pattern composed of dark spots two times greater than the spiracles, occurring posteriorly from the eye region ( Fig. 10D ). The neurocranium and claspers of these specimens were not examined due to the unavailability material. This population is temporarily identified here as S. canicula until more data are available. Expeditions to collect specimens of Scyliorhinus along northwestern Africa and in the Indian Ocean are really necessary due to the scarcity of data in these regions.

Figures

FIGURE 10. Clasper skeleton of Scyliorhinus species distributed along the southwestern Atlantic; dorsal view of skeleton. A, Scyliorhinus cabofriensis, UERJ 1702, 468 mm TL; B, S. haeckelii, UERJ 2233.6, 449 mm TL; C, S. ugoi, UERJ 1725, 530 mm TL. end, endstyle; rd, dorsal marginal cartilage; rh, rhipidion; rv, ventral marginal cartilage; td, dorsal terminal cartilage; td2, dorsal terminal 2 cartilage; tv, ventral terminal cartilage; tv2, ventral terminal 2 cartilage. Modified from Soares et al. (2015, 2016). Scale bar = 5 mm.

FIGURE 12. Neotype of Scyliorhinus canicula (Linnaeus, 1758), NHMUK 1866.9.10.4, male, 417.1 mm TL (Nice, France). A, dorsal view; B, lateral view. Scale bar = 20 mm.

FIGURE 13. Scyliorhinus canicula; dorsal view. A, NRM 50450, female, 468.6 mm TL (Skagerrak, Sweden); B, MNHN 1999–1732, female, 418.5 mm TL (Roscoff Station, France, 48°53’1.2”N, 3°58’58.8”W); C, ZMH 100467, female, 411.9 mm TL (North Sea, 52°56’N, 2°50’E); D, USNM 221602, female, 258 mm TL (Western Morocco, 35°09’N, 6°32.20’W). Scale bar = 20 mm.

FIGURE 14. Scyliorhinus canicula. A, C, NRM 50183, male, 582.4 mm TL (Southern Bohüslan, Sweden); B, D, E, F, MNHN 1999–1732, female, 418.5 mm TL (Roscoff Station, France, 48°53’1.2”N, 3°58’58.8”W); G, NHMUK 1983.8.3.1–4, male, 585.7 mm TL (Dale Roads, Pembrokeshire, United Kingdom). 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 and claspers. Scale bar = 20 mm.

FIGURE 15. Teeth of Scyliorhinus canicula; labial view. NHMUK 1970.12.2.1–4, female, 413.6 mm TL (Malaga Bay, Spain). a, anterior tooth; c, commissural; l, lateral; ps, parassymphysial. Scale bar = 100 µm.

FIGURE 16. Dermal denticles of Scyliorhinus canicula. A–C, NHMUK 1970.12.2.1–4, female, 413.6 mm TL (Malaga Bay, Spain); D–F, NHMUK 1983.8.3.1–4, male, 585.7 mm TL (Dale Roads, Pembrokeshire, United Kingdom). 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 17. Clasper of Scyliorhinus canicula; dorsal view, NHMUK 1983.8.3.1–4, 585.7 mm TL (Dale Roads, Pembrokeshire, United Kingdom). A, external morphology; B, skeleton. crh, cover rhipidion; end, endstyle; erh, exorhipidion; hp, hipopyle; rd, dorsal marginal cartilage; rv, ventral marginal cartilage; td, dorsal terminal cartilage; t3, terminal 3 cartilage; td2, dorsal terminal 2 cartilage; tdc, terminal dermal cover; tv, ventral terminal cartilage; tv2, ventral terminal 2 cartilage. Scale bar = 10 mm.

FIGURE 18. Map showing the geographic distribution of Scyliorhinus canicula based on material examined in this study. Black star indicates the neotype locality.

FIGURE 19. Egg capsules of Scyliorhinus species. A, S. canicula, AMNH 4121 (Naples, Italy); B, S. capensis, SAIAB 6286 (Algoa Bay, South Africa); C, S. retifer, AMNH 15611 (United States). Scale bar = 10 mm.

Tables

TABLE 4. Morphometric and meristic data of Scyliorhinus canicula. 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)	417.1	298	89.1–718.0	385.9	132.3
Precaudal length	76.0	298	70.6–76.4	75.7	2.0
Eye-spiracle length	0.7	298	0.5–1.6	1.0	0.2
Prenasal length	2.3	298	1.7–4.5	2.7	0.6
Preoral length	3.8	297	2.9–7.5	4.2	0.8
Preorbital length	5.3	298	4.6–9.2	5.9	0.8
Prespiracular length	9.2	298	7.4–13.9	9.7	0.9
Prebranchial length	12.8	298	9.7–18.2	13.4	1.1
Head length	17.5	298	15.0–22.8	18.5	1.3
Prepectoral length	16.1	298	13.8–21.4	17.0	2.2
Prepelvic length	37.2	298	31.7–48.5	38.6	2.4
Snout-vent length	39.8	298	42.6–51.4	42.2	3.1
Vent-caudal length	61.1	298	46.4–61.0	60.0	3.1
Pre-first dorsal length	46.5	298	42.0–58.0	47.7	4.2
Interdorsal distance	12.3	298	9.5–15.0	12.1	1.9
Dorsal-caudal distance	4.4	298	3.2–8.3	5.3	1.2
Pectoral-pelvic distance	16.3	295	12.0–21.7	16.4	2.2
Pelvic-anal distance	11.8	296	7.1–15.0	10.5	1.4
Anal-caudal distance	8.6	296	5.6–10.6	7.7	1.3
Interorbital distance	5.6	298	3.4–10.1	6.4	0.9
Internarial distance	4.5	297	2.2–7.7	4.6	0.5
Mouth length	5.1	296	2.2–7.4	4.8	0.6
Mouth width	7.4	293	3.2–9.7	7.6	0.8
Lower labial furrow length	3.4	295	1.5–4.3	3.2	0.4
Eye length	3.5	297	2.9–5.1	3.8	0.4
Eye height	1.2	297	1.7–2.6	1.3	0.3
Spiracle length	0.6	295	0.6–1.5	0.9	0.6
First gill slit height	2.9	296	1.2–4.2	3.1	0.7
Fifth gill slit height	1.4	296	0.8–2.2	1.6	1.0
Pectoral length	12.7	298	9.7–16.4	13.5	1.4
Pectoral anterior margin	13.9	298	11.2–18.0	14.4	1.5
Pectoral base	5.3	298	3.5–8.7	6.5	0.7
Pectoral posterior margin	8.5	298	4.9–12.1	8.5	1.4
Pectoral inner margin	6.1	298	4.4–10.8	7.0	0.8
Pelvic length	13.5	298	9.7–16.9	12.8	1.6
Pelvic anterior margin	7.8	298	4.1–10.3	8.0	0.9
Pelvic posterior margin	9.7	297	4.7–10.8	7.7	1.5
Pelvic base	8.5	296	3.6–9.8	8.5	1.1

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