Pilumnus trispinosus ( Sakai, 1965 )

deVries, Maaike, McGillis Hall, Linda, Dainty, Katie, Fan, Mark, Tscheng, Dorothy, Hamilton, Michael & Trbovich, Patricia, 2024, Ten Species of Crabs of the Families Acidopsidae, Aphanodactylidae and Pilumnidae (Crustacea: Decapoda: Brachyura) from the Ogasawara Islands, Japan, Bulletin of the National Museum of Nature and Science. Series A, Zoology 50 (4), pp. 155-169 : 164-165

Pilumnus trispinosus ( Sakai, 1965) [Jn: Toranoogani-damashi]

( Fig. 3E–F )

Parapilumnus pearsei (Rathbun) : Sakai 1939, p. 544, fig. 58.

Parapilumnus trispinosus Sakai, 1965, p. 160 (in English), p. 69 (in Japanese), pl. 79 fig. 5; 1976, p. 502 (English vol.), p. 309 (Japanese vol.), fig. 268. — Takeda & Miyake, 1969, p. 139, fig. 15. — Dai et al., 1986, p. 350, fig. 183 (2), pl. 50 fig. 7. — Dai & Yang, 1991, p. 376, fig. 182 (2), pl. 59 fig. 7. — Muraoka, 1998, p. 45. — Hsueh et al., 2009, p. 1025. — Števčić, 2011, p. 135 (Type designation of Daipilumnus gen. nov.).

Material examined. ɹ Chichi-jima Is. —Futami Bay, Chichi-jima I., on buoy, 1 ˁ (cb 6.2×cl 4.7mm), 1 ovig. ˂ (cb 6.6×cl 5.2 mm), NSMTCr 6866, 17-V-1975, coll. by Y. Kurata. — Miyano-hama, Chichi-jima I., 1 ovig. ˂ (cb 4.2×cl 3.0 mm), 26-VI-1976, NSMT-Cr 6552, coll. by M. Takeda; Same place, 1 ˁ (cb 6.1×cl 4.8mm), 26-VII—8-VIII-1976, NSMT-Cr 7038, coll. by M. Takeda. ʕ Tsuri-hama, Chichi-jima I., 1 ovig. ˂ (NSMT-Cr 32403; cb 6.3×cl 4.5 mm), 1 ˁ (NSMT-Cr 32404; cb 3.7×cl 3.0 mm), 11-VII-2009, coll. by H. Komatsu.

Comparative specimens examined. ɹ Sunosaki, Tanega-shima I., south of Kyushu, 1 ˁ, 4 ovig. ˂˂, 1 ˂, NSMT-Cr 5190, 14-VI-1975, coll. by M. Takeda.

Remarks. ɹ Števčić (2011) established a new genus Daipilumnus to accommodate Parapilumnus trispinosus Sakai, 1965 , without mention about the related genera and the definitive generic characters. The definition may be extracted only from the summarized explanations by Sakai (1939, as P. pearsei ; 1965), without definite reason to establish the genus distinct from Pilumnus , and therefore, Daipilumnus is generally considered to be a junior subjective synonym of Pilumnus .

The present specimens from the Ogasawara Islands ( Fig. 3E–F ) agree with the colored figure by Sakai (1965, pl. 79 fig. 5) rather than the line drawing by Sakai (1939, fig. 58) in the carapace anterolateral armature. In the line drawing, the three anterolateral teeth are figured as small teeth curving forward along the anterolateral margin, but in the colored figure, the anterolateral teeth are rather tuberculated, directed obliquely forward and protruding distinctly beyond the anterolateral margin. These teeth may be variable individually like in the case of Pilumnopeus pearsei , to which the smooth and scantly hairy dorsal surface of the carapace is close. In this species, both chelipeds are quite different in size like in Benthopanope indica , but the larger chela is covered with thick minute granules and dense short and scant longish hairs ( Fig. 3E–F ) in contrast with the smooth and shining chela of P. pearsei ( Fig. 3C–D ).

Sakai (1965) did not designate the type specimens, nor recorded the type depository. There is no specimen of P. trispinosus in the Showa Memorial Institute, National Museum of Nature and Science , Tokyo .

Distribution. Sagami Bay to Kyushu in the Japanese mainland, and Amami-Oshima Island to the Yaeyama Group in the Ryukyu Islands; Shihmen, Taipei County, Taiwan; Guangxi coast, southern China; Koror Island, Palau Islands; Suva, Fiji.

Figures

Fig. 3. A–B: Actumnus simplex Rathbun, ˁ (NSMT-Cr 32392; cb 6.7×cl 5.4mm) found in stomach contents of sidespot goatfish, Parupeneus pleurostigma (Bennett) from off Futami Bay, Chichi-jima I. C–D: Pilumnopeus pearsei (Rathbun), ovig.˂ (NSMT-Cr 32396; cb 5.2×cl 3.7mm) from Futami Bay, Chichi-jima I. (preserved in 75% ethanol). E–F: Pilumnus trispinosus (Sakai), ovig.˂ (NSMT-Cr 6866; cb 6.6×cl 5.2 mm) from Futami Bay, Chichi-jima I. (E) (preserved in 75% ethanol.); Ovig.˂ (NSMT-Cr 32403; cb 6.3×cl 4.5mm) from Tsuiri-hama, Chichi-jima I. (F).