Scyliorhinus cabofriensis Soares, Gomes & Carvalho, 2016, sp. nov.

• Main Authors: Soares, Karla D. A., Gomes, Ulisses L., De Carvalho, Marcelo R.
• Format: Text
• Language: unknown
• Published: Zenodo 2016
• Subjects: Biodiversity; Taxonomy; Animalia; Chordata; Elasmobranchii; Carcharhiniformes; Scyliorhinidae; Scyliorhinus; Scyliorhinus cabofriensis; Indian; Boa; Sudeste; Canicula; Muñoz; Teardrop; North Atlantic
• Online Access: https://dx.doi.org/10.5281/zenodo.6089781; https://zenodo.org/record/6089781

Scyliorhinus cabofriensis sp. nov. (Figs. 1 –8, 21, 24; Tabs. 1–5) Scyliorhinus sp.: Nunan & Senna, 2007, p. 167, figs. 1 c, d (brief account, figured). Scyliorhinus sp. 2: Soares, 2014, pp. 85–90, figs. 25, 73 (morphological account, figured). Holotype . MNRJ 40730, female, 395 mm TL (off Cabo Frio, Rio de Janeiro, southeastern Brazil). Paratypes . MCP 47874, immature female, 313 mm TL, (Rio de Janeiro, southeastern Brazil); MCP 47875, female, 325 mm TL (Rio de Janeiro, southeastern Brazil); MCP 47876, immature female, 276 mm TL (Rio de Janeiro, southeastern Brazil); MNRJ 40731, immature female, 285 mm TL (Rio de Janeiro, southeastern Brazil); MNRJ 40732, adult male, 420 mm TL (Rio de Janeiro, southeastern Brazil); MNRJ 40733, immature female, 281 mm TL (Rio de Janeiro, southeastern Brazil); MZUSP 37284, adult male, 393 mm TL (Rio de Janeiro, southeastern Brazil); UERJ 2042, female, 401 mm TL (Rio de Janeiro, southeastern Brazil); UERJ 2231.2, mature male, 454 mm TL (Rio de Janeiro, southeastern Brazil); UERJ 2231.4, female, 393 mm TL (Rio de Janeiro, southeastern Brazil). Additional material examined . 12 specimens (see Appendix). Diagnosis . A southwestern Atlantic Scyliorhinus species distinguished by its color pattern composed of randomly and asymmetrically distributed black and white spots of varied sizes (but predominantly small) ( vs . spots predominantly within saddles and with approximate bilateral symmetry in S. haeckelii and in S. ugoi ); saddles not well defined and without sharp median projections ( vs . well-defined saddles in S. haeckelii and saddles with sharp median projections in S. ugoi ); claspers with a well-developed groove on the terminal portion of the ventral terminal cartilage ( vs . lacking groove or an undeveloped groove in S. haeckelii and S. ugoi ); envelope absent and exorhipidion poorly developed ( vs . envelope present and exorhipidion developed in S. haeckelii ); and neurocranium with a proportionately broader basal plate ( vs . narrow basal plate in S. haeckelii and in S. ugoi ). The following combination of characters, although less conspicuous, also distinguishes these species: snout rounded and small, mean of preoral length 5 % TL ( vs. mean 4.5 % TL in S. haeckelii ); head moderately broad and depressed, its length 19.7–20.8 % TL ( vs . 17.5–19.2 % TL in S. haeckelii ); first dorsal fin triangular, never subrectangular ( vs . sometimes subrectangular in S. haeckelii ); interdorsal space two times dorsal-caudal space ( vs. 1.2–2 times in S. haeckelii and 2.1–2.5 in S. ugoi ); ventral terminal 2 cartilage slender and positioned on ventral terminal cartilage, its length 1.5 times length of ventral terminal cartilage ( vs . 1.8 times in S. haeckelii ); components of clasper proportionately larger than in S. haeckelii somewhat small sized adult males, at about 393 mm TL, and adult females, at least 420 mm TL ( vs . 445 mm and 500 mm TL, respectively, in S. ugoi ). Description . Morphometric data are given in Table 1, and neurocranial measurements in Table 5. Modes of meristic counts are given, along with their range, in parentheses, when values differ. Body slender and cylindrical, tapering considerably to caudal fin (Figs. 1, 2). Prepectoral length 18.3–19.1 % TL and prepelvic length 40.6–42.8 % TL (42.5–42.8 % TL in adult females vs. 40.6–42.4 % TL in adult males). Snout-vent length proportionally longer in adult females (45–45.9 % TL vs. 42.7–44.7 % TL in males), whereas the caudal region is proportionally longer in adult males (53.3–54.1 % TL vs. 51.2–52.7 % TL in females). Snout-vent length 0.7–0.8 times vent-caudal length. Pectoral-pelvic and anal-caudal spaces proportionately longer in adult females (16.9–19.6 % TL and 11–12.1 % TL, respectively), whereas the pelvic-anal space is greater in adult males (13.4–14.2 % TL). Pectoral-pelvic space 1.2–1.5 times the pelvic-anal space. Interdorsal space 2 times the dorsalcaudal space (Tab. 1). Head moderately broad and depressed, greatest width 0.58 times head length (Figs. 1, 2). Snout relatively short, preoral length 4.6–5.7 % TL and 0.5–0.7 times mouth width. Head length 19.7–20.8 % TL and 1.5 times head width. Preoral length 1.2–1.4 times in preorbital length (Tab. 3). Sexual dimorphism in snout and mouth shape present (Figs. 2, 3). Eyes large and slitlike, eye length 2.8 times its height and 0.2 times in head length (Figs. 1, 2). Eyes dorsolateral on head, with lower edges medial to horizontal head rim in dorsal view; subocular ridges strong. Nictitating lower eyelids of rudimentary type ( sensu Compagno, 1970), with shallow subocular pouches and secondary lower eyelids free from upper eyelids. Prespiracular length approximately 11 % TL (Tab. 1). Nostrils (Fig. 3) with broad incurrent apertures, without nasoral grooves or nasal barbels, small oval excurrent apertures and small posterior nasal flaps. Anterior nasal flaps large, covering posterior nasal flaps and excurrent apertures, extending just anterior to mouth. Internarial space 2.8 times in interorbital space. Mouth arched, moderately large and short, its length 3.6–7.2 % TL and 1.9 times in mouth width (Fig. 3). Lower labial furrows short and narrow, 4.3 times in mouth width; upper labial furrows absent. Dorsal labial cartilages 1.5 times the ventral labial cartilages; anterior tip of dorsal cartilages reaching orbital processes of palatoquadrate. 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. Measurements Scyliorhinus cabofriensis sp. nov. Scyliorhinus haeckelii Holotype Mean Range Holotype Mean Range MNRJ 40730 (n = 23) MNRJ 494 (n = 125) . .....continued on the next page Measurements Scyliorhinus cabofriensis sp. nov. Scyliorhinus haeckelii Holotype Mean Range Holotype Mean Range MNRJ 40730 (n = 23) MNRJ 494 (n = 125) Teeth morphologically similar in both jaws; tooth count 53 / 46 (45–58 / 44–50) rows, in 3 / 3 (2–3 / 2–3) functional series (Tab. 2). Sexual heterodonty weak; adult males presenting longer teeth and undeveloped lateral cusps on central portion of lower jaw. Upper teeth with slightly higher crowns than lower teeth, and with longer, stronger transverse ridges. Medial teeth and poorly differentiated symphysial teeth with higher crowns but smaller than anteroposteriors, with erect or semi-erect cusps and one weak cusplet on either side of main cusp. Anteroposteriors in both jaws larger than medials and symphysials, with semi-oblique cusps, usually with one high cusplet on either side, with strong basal ledges and grooves, longitudinal ridges confined to the basal ledges, and low, flat roots. Gradient monognathic heterodonty well-developed in anteroposterior teeth; anteroposteriors smaller distally, with thicker and more oblique cusps and lower cusplets. (n = 8) (n = 18) Propterygial radials 1 1 1 1 Mesopterygial radials 3–4 4 3–4 4 Metapterygial radials 8 8 7–9 9 Pelvic radials 13–15 14 13–16 15 Anal fin radials 19–21 19 17–22 20 1 st dorsal radials 12–13 12 11–14 12 2 nd dorsal radials 10–11 10 9–12 10 Monospondylous vertebrae 37–39 39 36–40 38 Total vertebrae 120–124 122 117–127 124 Upper tooth rows 45–58 53 48–54 52 Lower tooth rows 44–50 46 42–53 49 Lateral trunk denticles with flat, elongated teardrop-shaped crowns, 1.6–1.9 times as long as wide, anterior part covered with ectodermal pits ( sensu Muñoz-Chápuli, 1985) (Fig. 4). Crown with a strong medial ridge extending its entire length onto long medial cusp. Lateral cusps poorly developed, 0.3 times medial cusp; lateral ridges anterior to them very short or absent. Males with dermal denticles longer than females. Density of dermal denticles on posterior regions lower than on anterior regions (Tab. 3). Measurements Pectoral 1 st dorsal fin 2 nd dorsal fin Pectoral fins large and rounded-triangular, not falcate, with narrowly rounded apices and broad bases (Figs. 1, 2). Origin of pectorals under interspace between third and fourth gill openings. Pectoral base 0.8 times mouth width. Pectoral anterior margin 2 times its base and 1.5 times the posterior margin. Pectoral fin skeleton aplesodic with radials mostly divided into three segments; longest distal segment (DRA) 1.8 times length of its proximal segment (PRA). Total pectoral fin radial counts 13 (13–15) (Tab. 2). Pelvic fins triangular (Figs. 1, 2); pelvic anterior margins 0.9–1.1 times posterior margin. Males with anterior and posterior margins of pelvic fins proportionately larger than females. Total pelvic fin radial counts 14 (13–15) (Tab. 2). Claspers short, slender and cylindrical (Fig. 5 a); sometimes extending beyond free rear tips of pelvic fins; clasper inner length 1.1–1.4 times pelvic anterior margin. Most of clasper except apopyle (AP), dorsomedial region of glans, hypopyle (HP), rhipidion (RH) and terminal dermal cover (TDC) covered by dermal denticles with anteriorly directed crowns. Exorhipidion (ERH) poorly developed its length 15.3 % of clasper inner length (CLI). Clasper hooks and envelope absent. Rhipidion well-developed, partly covered medially by a poorly differentiated exorhipidion and anteriorly by cover rhipidion (CRH); insertion of rhipidion at posterior portion of accessory dorsal marginal cartilage (RD 2) (Fig. 5 b). Cover rhipidion about 12.2 % CLI (Tab. 4). Apopyle and hypopyle connected by a long clasper groove, with its dorsal margins over clasper groove. Pseudosiphon poorly developed and only v i s i b l e internally; pseudopera absent. A terminal dermal cover located in the hindmost portion of clasper, covering 1 / 4 of the ventral terminal cartilage (TV) and contacting the exorhipidion. Measurements S. cabofriensis sp. nov. S. haeckelii Clasper skeleton relatively simple (Fig. 6 a). Ventral marginal cartilage 31 % CLI, and dorsal marginal 36.3 % CLI (Tab. 4). A small and subtriangular accessory dorsal marginal cartilage present between terminal portion of dorsal marginal cartilage and anterior portion of dorsal terminal cartilage (TD). Terminal portion of clasper spoonshaped; dorsal terminal cartilage slightly shorter than ventral terminal. Prominent groove (GR) present in terminal portion of ventral terminal cartilage (Fig. 6 b). Accessory terminal cartilage and dorsal terminal 2 cartilage absent, but a slender ventral terminal 2 cartilage (TV 2) present on ventral terminal cartilage. End-style (G) elongated and extending between terminal cartilages. First dorsal fin triangular, never square-tipped, with nearly straight anterior margin, rounded apex and angular free rear tip (Figs. 1, 2). First dorsal origin above insertions of pelvic fins. Anterior margin 1.5–1.7 times first dorsal base; first dorsal height 0.7–0.8 times its base. First dorsal inner margin slightly longer in adult females than in males. Total radial counts 12 (12–13) (Tab. 2). Second dorsal fin low and triangular, never subrectangular (Figs. 1, 2). Second dorsal fin origin slightly behind anal midbase. Anterior margin 1.1–1.5 times base of second dorsal fin; second dorsal base 1.5 times its height and equal to dorsal-caudal space. Total second dorsal radial count 10 (10–11) (Tab. 2). First dorsal fin 1.2–1.3 times larger than second dorsal fin (Tab. 1). Anal fin low, apically narrow, not falcate and somewhat larger than second dorsal fin (Figs. 1, 2); anal fin base 1.6 times second dorsal fin base. Anal anterior margin nearly straight, apex narrowly rounded, free rear tip acutely pointed, and inner margin straight. Anal fin base 0.7–0.8 times interdorsal space and 1.6 times dorsalcaudal space. Anal anterior margin 1.4–1.8 times posterior anal margin; anal fin height 0.4 times anal base. Total anal radial counts 19 (19–21) (Tab. 2). Caudal fin (Figs. 1, 2) narrow-lobed and asymmetrical, with well-developed terminal lobe. Caudal fin 22 % TL. Dorsal caudal lobe 2.2 times larger than ventral lobe; subterminal caudal margin 0.9–1 times terminal margin. Dorsal caudal margin slightly convex, without lateral undulations. Denticles on caudal fin margins lacking crests. Total vertebral counts 122 (120–124), monospondylous precaudal centra (MP) 39 (37–39). Transition between MP and diplospondylous (DP) centra posterior to pelvic bases and over clasper shafts. Last MP centrum before MP–DP transition smaller than other MP centra and larger than the first DP, not forming a 'stutter zone' of alternating long and short centra. Intestinal valve of conicospiral type, with 7 (6–8) turns. Neurocranium broad and somewhat flattened, corresponding to approximately 10 % TL (Fig. 7, Tab. 5). Rostral cartilages short and slender; rostrum length 25.8–30.7 % of nasobasal length (NL). Distance between lateral rostral cartilages (LR) proportionately larger in females (15.4–16.6 % of NL) than in males (9.3–13 % NL). Nasal capsules (NC) large, oval-shaped and expanded laterally, their width equal to their length. Width across capsules proportionately larger in females (76.2–77 % NL) than in males (69.7–71.7 % NL). Females with wider nasal openings (25.6–26.2 % of NL) than males (18.6–23.9 % of NL). Distance between rostral base and anterior edge of anterior fontanelle (AF) 40 % of NL. Anterior fontanelle broad and subrectangular in males and heart-shaped in females, 1.3 times larger in females than in males. Basal plate (BP) flat, without keels, its width 37.2–45.6 % of NL. Orbits oval to subrectangular, their length 2.2–2.5 times in nasobasal length. Orbits proportionately larger in females (46.8–47.6 % NL) than in males (39.1–39.5 % NL). Postorbital processes (PTP) angular, situated on anterior ends of otic capsules; width across postorbital processes 1.5 times preorbital processes (PEP). Otic capsules short, their length 5 times in nasobasal length and width 2.5–2.7 times otic capsule length. Measurements Scyliorhinus cabofriensis sp. nov. Coloration . Color pattern with black and white spots of varied sizes but predominantly spiracle-sized, randomly distributed and without approximate bilateral symmetry. Saddles not well defined and without sharp median projections. Lunate spots larger and more frequent in males than in females; males more pigmented and presenting more minute white spots (Figs. 1, 2). Distribution and biological data . Known to occur only off the northeastern coast of the state of Rio de Janeiro, Brazil (Fig. 8), at 536 m in depth (Nunan & Senna, 2007). The species overlaps in distribution with Scyliorhinus haeckelii , but may occupy greater depths. Males range in size from 308–468 mm (n = 8) and females from 276–450 mm (n = 16). Size of first maturity not precisely defined, but males have well-developed claspers at 393 mm TL. Egg-capsules and other evidence that would help establish size of maturity in females without dissection have not been found. Stomach contents include squid beaks and skeletal elements of bony fishes. Etymology . The specific name refers to its type and only known locality, off Cabo Frio in northeastern Rio de Janeiro state. Comparisons with other species of Scyliorhinus . Scyliorhinus cabofriensis differs from almost all other Scyliorhinus species by its color pattern, with black and white spots of varied sizes scattered randomly over the back, but predominantly small and spiracle-sized, without a characteristic pattern of well-defined saddle-like blotches. It is more similar in color pattern to S. canicula (Linnaeus, 1758) from the eastern North Atlantic, British Isles and Mediterranean Sea, but differs from it by the lack of nasoral grooves and nasal flaps connecting to each other at the level of the upper jaw symphysis. Besides the color pattern, Scyliorhinus cabofriensis differs from S. haeckelii by the presence of a groove in the terminal region of the ventral terminal clasper cartilage, lacking the envelope in the clasper and in having a poorly developed exorhipidion, as well as having a neurocranium with a broader posterior aspect. It also has a greater preoral length, its first dorsal fin is always triangular, and components of the clasper are proportionately larger ( vs . a smaller preoral length, first dorsal fin sometimes subrectangular, and clasper components proportionately smaller in S. haeckelii ). Other proportional dimensions that further help differentiate both species are given in Table 1. Scyliorhinus cabofriensis has a head width 1.5 times smaller, and length at sexual maturity (possibly about 355 mm TL) smaller than S. ugoi (at about 450 mm TL). The anterior and posterior well defined, sharp median projections present in the dorsal saddles of S. ugoi are absent in S. cabofriensis (see Diagnosis for additional characters separating S. cabofriensis from S. ugoi ). Scyliorhinus cabofriensis differs from S. boa by its color pattern in which the dark spots are widespread on the back and not just around the saddles. It is also different from S. retifer in coloration, lacking its conspicuous reticulate color pattern. Scyliorhinus cabofriensis is easily distinguished from S. hesperius Springer, 1966 by having numerous conspicuous and spiracle-sized white spots scattered on the body, as well as by having black spots. It differs from S. torazame (Tanaka, 1908), S. comoroensis Compagno, 1988 b, S. capensis (Müller & Henle, 1838), S. meadi Springer, 1966, and S. torrei by its color pattern and geographical distribution. While sharing similar inconspicuous saddles with S . stellaris (Linnaeus, 1758) and S . garmani (Fowler, 1934), most of the black spots in S. cabofriensis are spiracle-sized ( vs. greater and predominantly brown spots in both S. stellaris and S. garmani ). : Published as part of Soares, Karla D. A., Gomes, Ulisses L. & De Carvalho, Marcelo R., 2016, Taxonomic review of catsharks of the Scyliorhinus haeckelii group, with the description of a new species (Chondrichthyes: Carcharhiniformes: Scyliorhinidae), pp. 501-534 in Zootaxa 4066 (5) on pages 503-513, DOI: 10.11646/zootaxa.4066.5.1, http://zenodo.org/record/260947 : {"references": ["Nunan, G. W. & Senna, M. L. V. (2007) Tubaroes (Selachii) coletados pelo navio oceanografico Thalassa sobre a plataforma externa e talude continental do Brasil entre 11 \u00b0 e 22 \u00b0 S. In: Costa, P. A. S., Olavo, G. & Martins, A. S. (Eds.), Biodiversidade da fauna marinha profunda na costa central brasileira. Museu Nacional, Rio de Janeiro, pp. 163 - 183.", "Soares, K. D. A. (2014) Estudo taxonomico das especies de Scyliorhinus do grupo haeckelii / besnardi (Carcharhiniformes, Scyliorhinidae) das regioes Sudeste e Sul do Brasil (Oceano Atlantico Sul Ocidental). Unpubl. 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