Squalus acutirostris Chu, Meng & Li, 1984

White, William T. & Last, Peter R., 2013, Notes on shark and ray types at the South China Sea Fisheries Research Institute (SCSFRI) in Guangzhou, China, Zootaxa 3752 (1), pp. 228-248 : 229-230

Squalus acutirostris Chu, Meng & Li, 1984

(= Squalus mitsukurii Jordan & Snyder in Jordan & Fowler, 1903)

( Figure 1 )

Squalus acutirostris Chu, Meng & Li, 1984: 283 , fig. 1 (South China Sea)— Muñoz-Chápuli & Ramos, 1989: 6 (misidentification).

Material examined. SCSFRI D 01562 (holotype), adult male 648 mm TL, South China Sea, 18°51'– 18°47' N, 112°41'– 112°33' E, depth 394 m, 21 Apr 1982 .

Remarks. Described by Chu et al. (1984) based on four specimens collected from the South China Sea. This species has been considered valid by some authors (e.g. Muñoz-Chápuli & Ramos, 1989), but Compagno et al. (2005a) did not treat this as a valid species of Squalus . Muñoz-Chápuli & Ramos (1989) based their recognition of S. acutirostris as a valid species on a specimen from New South Wales, Australia, which matched the description of this species. However, examination of the morphological and meristic data presented by these authors for the Australian specimen indicates that it’s a then undescribed species of Squalus , which has since been described as Squalus grahami White, Last & Stevens, 2007 . The main characters confirming this identification are: low monospondylous centra (40) and longer snout (preoral length 10.5–11.3% TL vs. 9.3% TL in holotype of S. acutirostris ). Squalus grahami is a common species in the upper continental slope waters off New South Wales and is endemic to eastern Australia.

The S. acutirostris holotype ( Figure 1 ) is very similar morphologically to S. mitsukurii Jordan & Snyder in Jordan & Fowler, 1903, a common squalid species in the western North Pacific, particularly off Taiwan and Japan. Comparison of morphometric data taken from the holotype of S. acutirostris and the holotype and five other specimens of S. mitsukurii revealed very few differences ( Table 1). The only characters which differed between these two nominal taxa (in bold in Table 1) were precaudal length (PCL), interdorsal space (IDS), second dorsal-fin length (D2L), second dorsal-fin anterior margin (D2A), second dorsal-fin base length (D2B), and dorsal caudal margin (DCM). However, the differences in IDS, D2L, D2A and D2B are likely the result of difficulty in determining the origin of the second dorsal fin, which affects all of these measurements. Furthermore, the lateral images of S. acutirostris and S. mitsukurii ( Figs 1 and 2 ) do not suggest any difference in interdorsal space ratios. The differences in DCM and PCL are likely the result of the slightly damaged caudal fin tip in the S. acutirostris holotype. Although the total length could be determine relatively accurately due to the ceratotrichia of the caudal fin, the DCM was not as easy to accurately measure.

There appears to be no useful characters to distinguish S. acutirostris from S. mitsukurii . Squalus acutirostris should be considered a junior synonym of Squalus mitsukurii Jordan & Snyder in Jordan & Fowler (1903).

Figures

FIGURE 1. Holotype of Squalus acutirostris SCSFRI D 01562 (adult male 648 mm TL): A. lateral view; B. ventral head view; C. first dorsal fin; D. second dorsal fin.

FIGURE 2. Lateral view of Squalus mitsukurii (CSIRO H 7403–02, female 632 mm TL) from Taiwan.