Pilumnus curvipenis Komai and Motoh, 2012

Pilumnus curvipenis Komai and Motoh, 2012 View in CoL

( Fig. 4A View Fig )

Pilumnus dofleini Balss, 1933 View in CoL : Ng, 2000, p. 301, figs. 1–2. — Takeda & Komatsu, 2005, p. 284.

Pilumnus curvipenis Komai & Motoh, 2012, p. 17 View in CoL View Cited Treatment , figs. 12–13, 18A–B. — Takeda & Komatsu, 2020, p. 111.

Material examined. Takase submarine bank ( Fig. 1 View Fig ; 34°28.64′N, 139°12.26′E, 105 m depth), northwest off Nii-jima I., Izu Is., 1 8 (NSMT-Cr 11034; cb 4.7×cl 3.7 mm), 11-IX-1989, dredged by TV Umitaka Maru of Tokyo University of Fisheries (now, Tokyo University of Marine Science and Technology) and donated by T. Okutani; Takase submarine bank (34°26.11′N, 139°09.75′E, 112 m depth), 1 ovig.8 (NSMT-Cr 11052; cb 5.8×cl 3.8 mm), 11-IX-1989, dredged by TV Umitaka Maru GoogleMaps .

Comparative material examined. Shin-Kurose submarine bank ( Fig. 1 View Fig ; 33°32′N, 140°10′E), southeast off Mikura-jima I., Izu Is., 160–230 m depth, 3 ƏƏ, 1 ovig.8 (NSMT-Cr 6665), 26-XI-1974, T. Okutani leg. GoogleMaps ; Hyotanse submarine bank ( Fig. 1 View Fig ; 34°21′N, 139°02.36′E, 105 m depth), northwest off Kozu-shima I., Izu Is., 1 ovig.8 (NSMT-Cr 6666), 26-VI-1973, T. Okutani leg. GoogleMaps

Off Kasari Bay, Amami-Oshima I., Ryukyu Is., 120–122 m depth, 1 Ə (NSMT-Cr 16204; cb, left branchial region heavily deformed×cl 2.6 mm), dredged by tugboat Daiyu Maru No. 38; Off Nakahise-saki, Amami-Oshima I., 117–123 m depth, 1 ovig.8 (NSMT-Cr 16201; cb 5.0×cl 3.3 mm), by Daiyu Maru No. 38.

Remarks. The specimens from Shin-Kurose and Hyotanse (NSMT-Cr 6665, 6666) were recorded by Ng (2000) as Pilumnus dofleini Balss, 1933 , but later described as a new species, P. curvipenis , by Komai and Motoh (2012). One male (NSMT-Cr 6665; cb 11.4×cl 14.2 mm) was selected as the holotype, and two males (cb 8.0×cl 9.5 mm; cb 8.8×cl 10.2 mm) and one ovigerous female (cb 13.4×cl 16.4 mm) in the same lot were designated as the paratypes with new registered number, NSMT-Cr 22177, together with one ovigerous female (NSMT-Cr 6666; cb 12.3×cl 14.8 mm).

As for the specimens from Amami-Oshima Island, it is noted that Takeda and Komatsu (2005) recorded a male (MSMT-Cr 16204; cl 2.6 mm) as Pilumnus dofleini , and an ovigerous female (NSMT-Cr 16201; cb 5.0×cl 3.3 mm) as Nanopilumnus sp.

During this study, the type specimens (NSMTCr 6665, 6666, 22177) and additional two females (one ovigerous) (NSMT-Cr 11034, 11052) from submarine banks off the Izu Islands, and one male (NSMT-Cr 16204) and one ovigerous female (NSMT-Cr 16201) from off Amami-Oshima Island, Ryukyu Islands, were re-examined. The armature of the carapace anterolateral margins illustrated by Ng (2000, fig. 1a) and Komai and Motoh (2012, fig. 18A) seem to be somewhat different from each other. In the present specimens ( Fig. 4A View Fig ), the anterolateral teeth are not spinulate, but distinctly toothed, being close to those of the carapace right side in Komai and Motoh`s figure (fig. 18A). The most obvious character of P. curvipenis is the G1 shape as figured by Ng (2000, fig. 2b–e, as P. dofleini ) and Komai and Motoh (2012, figs. 13F–I). The distal part of the G1 is short and strongly bent, somewhat similar to that of P. bohol Komai and Motoh, 2012 in which, however, the distal part is shorter and only weakly curved, not vent at all.

The specimens from off Amami-Oshima Island previously reported as P. dofleini (NSMTCr 16204) and Nanopilumnus sp. (NSMT-Cr 16201) by Takeda and Komatsu (2005) agree well with the type specimens of P. curvipenis from the Izu Islands off the Pacific coast of central Japan, and also with notes on three females from the west of Amami-Oshima Island, 120 m depth, and a male from off Naha, Okinawa-jima Island, Ryukyu Islands, 60–70 m depth, made by Takeda and Komatsu (2020).

Distribution. Known from some submarine banks off the Izu Islands, south of Tokyo, and from off Amami-Oshima Island and Okinawa-jima Island in the Ryukyu Islands; 60–230m depth.