A new species ofScymnodalatias from the southern oceans, and comments on other squaliform sharks

Scymnodon plunketi (Waite, 1910): a junior synonym of Scymnodon macracanthus (Regan, 1906) (Somniosidae: Elasmobranchii)

“…That statement, however, was made based on a small sample. The inclusion of additional specimens proved that the difference pointed out by Taniuchi and Garrick (1986) was a result of intraspecific variation (Table 1). Across Somniosidae, the length of the dorsal fins can be highly variable, resulting from the variable extent of the dermal fleshy ridge that supports the anterior margin of the dorsal fins (Vaz, 2015).…”

“…In all species of Scymnodon, the anterior basal cartilage of the first dorsal fin is trapezoidal and large, approximately one-half the length of the dorsal-fin skeleton (Figure 4). In S. macracanthus and S. ichiharai the posterior basal is triangular and short, and its length is approximately one- The differentiation between S. macracanthus and S. plunketi has historically been restricted to a few morphological characteristics: the relative size of the pectoral fin, length of the snout, dimensions of the first dorsal fin and prominence of the dorsal-fin spines (Bigelow & Schroeder, 1957;Compagno, 1984;Garman, 1913;Taniuchi & Garrick, 1986). Garman (1913) proposed that in S. macracanthus the pectoral fin would extend posteriorly to the level of the origin of the first dorsal fin, whereas in S. plunketi the pectoral fins would not extend to the level of the first dorsal-fin origin.…”

Vertical distribution, diet, and reproduction of the velvet dogfish (Zameus squamulosus) in waters off Hawaii

“…The reproductive classification that we used for mature females had 7 stages: 1) developing ova, nongravid, with developing ovarian ova and expanded uteri (>10 mm); 2) large ova nongravid, with ova and expanded uteri (>10 mm); 3) ovulating, with eggs in body cavity; 4) uterine ova, ova in the uteri after ovulation; 5) developing embryos, obvious embryos with yolk sacs in the uteri; 6) near-term embryos, uterine embryos that have absorbed their external yolk sac; and 7) postpartum stage: no uterine embryos and large flaccid uteri (>20 mm). Although no near-term embryos were observed in utero in velvet dogfish collected off Hawaii, size at birth was estimated from lengths of near-term embryos (Graham 1 ; Romanov 2 ) and size of the smallest free-swimming individuals (Graham 1 ; Cadenat and Blache, 1981;Yano and Tanaka, 1984;Taniuchi and Garrick, 1986).…”

“…Size at birth for velvet dogfish is estimated at 245-270 mm TL on the basis of observations of embryos with yolk sac attached at sizes of 200-220 mm TL (A. Graham 1 ), free-swimming sharks 250-270 mm TL with faint umbilical scars (Graham 1 ; Romanov 2 ), and a 277-mm-TL free-swimming shark with an umbilical scar completely healed (Graham 1 ). The minimum sizes reported for free-swimming individuals were 246-262 mm TL (Cadenat and Blache, 1981;Yano and Tanaka, 1984;Taniuchi and Garrick, 1986;Graham 1 ). This information substantially narrows the range for estimates of size at birth from the large size (690 mm TL) previously reported by Burgess and Chin (2006) and the small size (200 mm TL) reported in Ebert (2015).…”

“…The velvet dogfish (Zameus squamulosus) is a dark, nondescript shark species with a wide distribution along the margins of the Atlantic, Pacific, and Indian ocean basins and at a number of insular regions, including the Canary Islands, Hawaii, Japan, New Zealand, Okinawa, and Palau (Compagno, 1984;Taniuchi and Garrick, 1986;Yano and Kugai, 1993;Wetherbee and Crow, 1996;Pajuelo et al, 2010). Although this species was placed in the genus Scymnodon before the revision by Taniuchi and Garrick (1986), the genus Zameus is genetically distinct from Scymnodon, and Zameus squamulosus is recognized as the valid name for the velvet dogfish (White et al, 2014). This species occurs as bycatch in a variety of fisheries, including those using trawls and pelagic or bottom longlines (Krefft, 1980;Yano and Tanaka, 1984;Nakaya and Shirai, 1992;Pajuelo et al, 2010;Zhu et al, 2012;Romanov et al, 2013) at depths of 27-2000 m (Compagno, 1984;Last and Stevens, 1994).…”