Redescription of Squalus acutipinnis Regan, 1908, a Valid Species of Spiny Dogfish from Southern Africa (Chondrichthyes: Squaliformes: Squalidae)
The Bluntnose spiny dogfish Squalus acutipinnis Regan, 1908 is redescribed based on the re-examination of its type specimens and non-type material from Southern Africa. The taxonomic confusion concerning its validity is mainly related to its heterogeneous type series. Its taxonomic status is clarified as a valid species endemic to the Southwestern Indian Ocean when compared to congeners from the region and other valid species with which it has been placed in synonymy. Squalus acutipinnis can be distinguished from all species of the “megalops-cubensis group” by fewer total, precaudal, and monospondylous vertebrae (except from Squalus megalops, Squalus brevirostris, and Squalus crassispinus). Squalus acutipinnis is clearly distinct from Squalus megalops from Southern Australia and the Japanese S. brevirostris through characters of pectoral fin and external measurements. The South African species differs from S. crassispinus by having more slender first and second dorsal-fin spines. Squalus acutipinnis is also easily distinguished from the regional congeners S. acanthias, S. blainvillei, and S. mitsukurii by having lanceolate dermal denticles (vs. non-lanceolate unicuspid denticles in S. acanthias, and non-lanceolate tricuspid denticles in S. blainvillei and S. mitsukurii).
Lectotype of Squalus acutipinnis, BMNH 1905.6.8.8, adult female, 578 mm TL from Kwazulu-Natal, South Africa: (A) lateral view; (B) ventral view; (C) first dorsal fin; (D) second dorsal fin.
Detail of the upper and lower teeth. (A) Squalus acutipinnis, BMNH 1905.6.8.8 (lectotype), female, 578 mm TL from Kwazulu-Natal, South Africa; (B) BMNH 1900.11.6.14 (paralectotype), female, 565 mm TL from Table Bay, South Africa; (C) Squalus megalops, AMS I 16255-001 (holotype), female, 550 mm TL from Port Jackson, Australia; (D) Squalus brevirostris, KAUM-I 377, male, 377 mm TL from Kagoshima, Japan.
External morphology of clasper of Squalus acutipinnis (SAIAB 10443, adult male, 410 mm TL from Cape Town, South Africa) in dorsal view. Abbreviations: accessory terminal cartilage (T3); apopyle (AP); clasper groove (CG); hypopyle (HP); pelvic fin (P2); rhipidion (RH).
Dermal denticles of Squalus acutipinnis. (A) BMNH 1905.6.8.8, female, 578 mm TL (photograph of lectotype). Scanning electron microscopy (SEM): (B) SAIAB 34576, female, 550 mm TL from Kwazulu-Natal, South Africa; (C) SAM 28638, female, 365 mm TL from False Bay, South Africa; (D) SAM 32894, male, 310 mm TL from Mossel Bay, South Africa. Scale bars: 100 μm. See Last et al. (2007) for comparisons with congeners.
Radiograph showing internal components of clasper. Squalus acutipinnis, SAIAB 10443, male, 410 mm TL. Abbreviations: accessory terminal cartilage (T3); axial cartilage (AX); beta cartilage (β); dorsal marginal cartilage (RD); dorsal terminal cartilage (TD); intermediate segment (b1); ventral marginal cartilage (RV); ventral terminal cartilage (TV).
Map of Southern Africa, showing the distribution of Squalus acutipinnis. Lectotype (yellow star), paralectotypes (yellow triangle), non-type specimens (yellow dots).
Paralectotype of Squalus acutipinnis, BMNH 1900.11.6.14, adult female, 565 mm TL from Table Bay, South Africa: (A) lateral view; (B) ventral view; (C) first dorsal fin; (D) second dorsal fin.
Lateral view of (A) Squalus acutipinnis, SAIAB 19863, female, 570 mm TL from Port Alfred, South Africa; (B) Squalus megalops, AMS I 45658-001, female, 625 mm TL from New South Wales, Australia; and (C) Squalus brevirostris, KAUM-I 185, female, 500 mm TL from Kagoshima, Japan.
Shape of pectoral fin (A, D, G), first dorsal fin (B, E, H), and second dorsal fin (C, F, I): (A, B, C) Squalus acutipinnis, SAIAB 34576, female, 578 mm TL from Kwazulu-Natal, South Africa; (D, E, F) Squalus brevirostris, HUMZ 189762, male, 403 mm TL from East China Sea; (G, H, I) Squalus megalops, AMS I 45658-001, female, 625 mm TL from New South Wales, Australia.
Contributor Notes
Associate Editor: W. L. Smith.