Cephaloscyllium ventriosum ( Garman 1880 )

Schaaf-Da, Jayna A. & Ebert, David A., 2008, Cephaloscyllium ventriosum (Garman 1880) (Chondrichthyes: Carcharhiniformes: Scyliorhinidae), with comments on the status of C. uter (Jordan & Gilbert 1896), Zootaxa 1872, pp. 59-68 : 62-64

Cephaloscyllium ventriosum ( Garman 1880)

( Figure 2 , Table 1)

Scyllium ventriosum Garman 1880: 167 .

Catulus uter Jordan & Gilbert in Jordan & Evermann 1896: 25, pl. 3, fig. 12; Starks 1917: 147, fig. 53.

Scyliorhinus ventriosus Regan 1908: 458 .

Cephaloscyllium ventriosum: Garman 1913: 80 , pl. 9, figs. 6–9; White 1937: 117; Kato et al. 1967: 24, fig. 36; Nelson & Johnson 1970: 732; Grover 1972b: 191; Miller & Lea 1972: 36 –37; Grover 1974: 359, figs. 1–3; Hubbs et al. 1979: 4; Springer 1979: 42, figs. 23–25; Castro 1983: 102; Eschmeyer et al. 1983: 32 –33, pl. 1; Compagno 1984: 303; Compagno 1988: 113, fig 13.9A; Ferguson & Cailliet 1990: 20 –22, 24, 32, 56; Michael 1993: 53; Love 1996: 55; Ebert 2003: 131; Compagno et al. 2005: 219, pl. 36; Love et al. 2005: 6.

Cephaloscyllium uter: Walford 1935: 28 , fig. 26; Jordan et al. 1930: 12; Beebe & Tee-Van 1941: 99; Roedel & Ripley 1950: 50, fig. 34; Roedel 1953: 17; Cox 1963: 283, fig. 11.

Type-species and locality. Holotype, MCZ 496, mature female, 748 mm TL, off Valparaiso, Chile (33°5'S, 71°40'W).

Diagnosis. Body comparatively stocky, head short and depressed, greatest height at eyes. Snout moderately flattened, extremely short, broadly rounded in dorsoventral view. Anterior nasal flaps broadly lobate or subtriangular, overlapping mouth posteriorly. Labial furrows absent. Teeth very small, similar in both jaws. Stomach inflatable, containing air or water. Supraorbital crests present on the chondocranium. Claspers short and stout. Color pattern includes light spots on body and fins, underside of head and abdomen spotted; fins without conspicuous light margins. A large species of swellshark.

Description. Proportional dimensions in percentage of total length are shown in Table 1. A robust species, large-sized. Head length 0.31 times precaudal length. Snout moderately flattened, short, broadly rounded, preorbital length 0.20 in head length and 0.65 times interorbital width. Pre-pectoral length 19.7% TL. Eye slit small, elongate-oval in shape, cat-like, with dorsal ridge on orbit, horizontal eye length 0.12 in head length. Spiracle small, near the eye, diameter 0.27 times horizontal eye length. Five gill openings present, small, posterior two over pectoral fin, vertical length of first gill opening 0.08 times head length. Mouth wide, its width 0.49 times head length; greatly arched, labial furrows absent. Anterior nasal flaps broadly lobate or subtriangular, overlapping mouth posteriorly; internarial distance 0.19 times mouth width. First dorsal-fin origin just posterior to pelvic-fin origin, Pre-first dorsal-fin length 55.3% TL; pre-second dorsal-fin length 0.86 times precaudal length. First and second dorsal fins small, first dorsal-fin height 0.60 in length; second dorsal-fin height 0.43 in length. Second dorsal fin smaller than first; second dorsal-fin height 0.53 in first dorsal fin; second dorsal fin smaller than anal fin and opposed to it; second dorsal-fin origin and anal-fin origin about opposite, or anal-fin origin slightly anterior; second dorsal-fin insertion and anal-fin insertion in line. Pectoral fins relatively large and broad; anterior margin 0.21 times head length; base 0.59 in anterior margin. Pelvic fin small; its length 0.14 times precaudal length; base 0.73 times in length, claspers short and stocky, clasper groove unfused between hypopyle and apopyle. Anal fin smaller than first dorsal fin; its height 0.05 times precaudal length and its length 0.11 times in precaudal length; second dorsal-fin height 0.73 times anal-fin height; anal-fin height 0.72 times first dorsal-fin height. Caudal fin broad, asymmetrical, with subterminal notch, dorsal-lobe length 0.26 times precaudal length; ventral-lobe length 0.44 times dorsal-lobe length.

Body firm and thick-skinned, with well calcified dermal denticles. Dermal denticles on sides of body and over most surfaces erect and needle-shaped; with a stout blade, triangular in shape with a single posterior point, blades nearly parallel to skin surface in ventral surfaces, more erect in dorsal surfaces, ventral denticles smooth without ridges, dorsal denticles with one to several ridges. Newly hatched young possess two rows of enlarged, paddle-shaped denticles with sharp blades along each side of the mid-dorsal line, from first gill slit to first dorsal-fin origin, most likely to aid in emerging from the egg case, shed soon after hatching ( Ebert 2003).

Teeth three to five cusped, in 3–4 series, similar in upper and lower jaws, sexual heterodonty absent. Tooth count: 54/54. Total vertebral number 109, monospondylous 42, precaudal 69, and pre-caudal diplospondylous 27.

Size and sexual maturity. Males mature at about 82–85 cm TL, with a maximum recorded size being over 110 cm TL; hatchlings emerge at 13–15 cm TL ( Compagno et al. 2005).

Coloration. Color pattern of yellow-brown background, with variegated nearly round dark brown blotches, 10 brown dorsal saddles, numerous light spots on body and fins, underside of head and abdomen spotted; fins without conspicuous light margins. Color is somewhat lighter in fresh specimens. Hatchlings have a similar pattern, but are lighter in color ( Ebert 2003). In the holotype, dorsal saddles are obscure and mottling is intense.

Biology. These sharks are usually found among rocks and kelp in shallow areas (20–40 m), but they have been taken from depths of 500 m as well as over sandy areas ( Grover 1972b; Love 1996). Nocturnal and generally solitary, they feed at night by ambushing prey in the lie-and-wait fashion ( Nelson & Johnson 1970). Cephaloscyllium ventriosum is oviparous, producing two egg cases per clutch. Cox (1963) described the egg case as large, unridged (i.e. not laminated), rectangular with thick tendrils; from 90–125 mm in length and 28– 55 mm in width. Anterior end with short, thick horns tapered to points extending as coiled tendrils, anterior horns bend acutely towards each other, often touching. Posterior end blunt, horns short, terminating into thick coiled filaments; thin margin between posterior horns deeply crescent-shaped. Anterior end slightly constricted, tapers gradually toward posterior end, neck of egg case constricted. Tendrils either long (80–200 cm) or short (2 cm). Freshly laid case transparent, light greenish-tan; holds a single egg seen through the case. Exposure to seawater somewhat darkens the case but it remains translucent ( Cox 1963). Eggs hatch in 7.5–10 months depending on water temperature ( Ebert 2003) and are apparently preyed upon by carnivorous snails ( Grover 1972a). Populations living near the mainland produce eggs with long tendrils, while those living around Santa Catalina Island have short tendrils ( Grover 1972b; Castro 1983; Love 1996).

This species is of no interest to fisheries; it is occasionally caught by divers and sportfishers, and often found in lobster and crab traps, but probably not utilized ( Compagno 1984; Ebert 2003). According to some reports, swellshark meat is mildly toxic ( Roedel & Ripley 1950; Love 1996).

Comparison with C. uter . Important morphometric characters used to separate other species of Cephaloscyllium fail to separate C. ventriosum from C. uter (Table 1). The first dorsal-fin base of C. ventriosum ranges from 7.4–10.3 %TL in the 16 specimens examined. The Chilean holotype has a first dorsal-fin base of 7.6% TL, which falls within this range. The first dorsal-fin height of C. ventriosum ranges from 4.9–7.5% TL in the California specimens, and 6.1% TL in the Chilean holotype, again falling within the range. The length of the caudal peduncle, measured by the dorsal–caudal space and the anal–caudal space, also fails to separate the northern and southern species (Table 1). Characters such as mouth width and internarial width do not uphold C. uter as valid either. The shape of the anterior nasal flap is very similar for both eastern North and eastern South Pacific specimens ( Fig. 3 ). Furthermore, the color pattern of heavy mottling and 10 dorsal saddles is comparable for all of the eastern Pacific specimens studied. There is a somewhat darker coloration in the Chilean holotype, but this could be due to different preservation methods. Both California and Chilean forms are of the large-size variety; the maximum size is about double that of a dwarf Cephaloscyllium species, e.g. C. fasciatum Chan 1966 . Ebert (2003) reports C. ventriosum to have a total vertebral count of 109–112; the holotype has 109. Also, Ebert (2003) reports C. ventriosum to have tooth counts of 55–69/46–85; the holotype has 54/54. Springer (1979) reports the spiral valve count as 10–11, but the holotype specimen could not be dissected, and so this could not be confirmed. No other key characters were identified that would distinguish C. ventriosum from C. uter .

Concerning many measurements, there was more variation among the different California specimens than between any California specimen and the Chilean holotype. For example, two specimens collected off Santa Barbara show great variation in the size and shape of the pectoral fin ( Fig. 4 ), more so than if either is compared to the Chilean holotype. Given the lack of characters to distinguish California and Chilean Cephaloscyllium , we conclude that only a single valid species, C. ventriosum , occurs in the eastern Pacific. Cephaloscyllium uter is therefore designated a junior synonym of C. ventriosum .

Distribution. Eastern Pacific: Central California (Monterey Bay) to Gulf of California and southern Mexico; central Chile ( Compagno et al. 2005), but more abundant south of Point Conception ( Love 1996). Cephaloscyllium ventriosum appears to be the only member of this genus to exhibit an antitropical geographic pattern as there are no records of this species occurring between Central America and northern Chile. The western North Pacific C. fasciatum has been reported to display an antitropical geographic pattern ( Compagno et al. 2005); however, supposed Australian records of this species have proven to be distinctly different ( White & Ebert, 2008).

Etymology. From the Latin ventriosus , meaning swell, refers to the common name and the ability to inflate the stomach.

Common name. Swellshark.

Figures

FIGURE 2. — Cephaloscyllium ventriosum holotype (MCZ 496), lateral view. Photo courtesy of the Museum of Comparative Zoology, Harvard University (© President and Fellows of Harvard College).

FIGURE 3. — Ventral view of the head, including morphology of the anterior nasal flaps of Cephaloscyllium ventriosum (MCZ 1230) collected from Santa Barbara, California (left), and C. ventriosum holotype (MCZ 496) collected from central Chile (right). Photo by J. A. S. - Da Silva.

FIGURE 4. – Pectoral fins of Cephaloscyllium ventriosum (MCZ 877) (left), and C. ventriosum (MCZ 1230) (right), both collected from Santa Barbara, California. Photo by J. A. S. - Da Silva.