Pilumnopeus pearsei ( Rathbun, 1932 )

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 : 162-163

Pilumnopeus pearsei ( Rathbun, 1932)

[Jn: Toranoogani]

( Fig. 3C–D )

Heteropanope pearsei Rathbun, 1932, p. 35 . — Sakai, 1936, p. 176, pl. 49 fig. 4.

Pilumnopeus indica (De Man, 1887) : Balss, 1933, p. 33. — Sakai, 1939, p. 542, pl. 62 fig. 4; 1965, pp. 159 (in English), 69 (in Japanese), pl. 79 fig. 4; 1976, pp. 500 (English vol.), 308 (Japanese vol.), pl. 178 fig. 2. — Dai et al., 1986, p. 348, fig., 182 (1), pl. 50 fig. 4. — Dai & Yang, 1991, p. 374, fig. 182 (1), pl. 50 fig. 4. — Muraoka, 1998, p. 45.

Hetereopanope (Pilumnopeus) indica (De Man, 1887) : Kim, 1973, p. 400, fig. 158, pl. 84 fig. 120.

Pilumnopeus indicus (De Man, 1887) : Miyake, 1983, p. 138, pl. 46 fig. 5.

Benthopanope indica (De Man, 1887) : Ho et al., 2000, p. 116. ʕ Ng et al., 2001, p. 30. ʕ Ko & Lee, 2012, p. 24, pl. 5. ʕ Ng et al., 2017, p. 62.

Benthopanope pearsei ( Rathbun, 1932) : Takeda et al., 2011, p. 67.

Pilumnopeus pearsei ( Rathbun, 1932) : Patel et al., 2024, pp. 386–393 (in discussion), figs. 6–7.

Material examined. ɹ Chichi-jima Is. —Ototo-jima I., 1 ˁ (NSMT-Cr 32395; cb 4.1×cl 3.3 mm), 10-VII-1969, coll. by M. Imajima. — Futami Bay, Chichi-jima I., on buoy, 1 ovig. ˂ (cb 5.2×cl 3.7 mm), NSMT-Cr 32396, 1 ovig. ˂ (cb 3.6×cl 3.3 mm), 1 ˂ (cb 4.0×cl 3.0 mm), NSMT-Cr 32397, 8-VII-2009, coll. by H. Komatsu; Futami Bay, Chichi-jima I., on rope at fish- ing port, 1 ˂ (cb 4.0×cl 3.5 mm), NSMT-Cr 32398, 17-XI-2009, coll. by H. Komatsu; Omura Beach (27°05′35′′N, 142°11′38′′E), Chichi-jima I., 3 m, 1 ˁ (cb 2.7×cl 2.5 mm), NSMT-Cr 32399, 30-VI-2014, coll. by H. Komatsu.

Comparative specimens examined. Nishinosaki , Hatsuse, Kanagawa Pref., Sagami Bay, 1 ˁ, NSMT-Cr R2840 , 21-VII-1963, coll. by His Majesty the Showa Emperor of Japan; Shibazaki, Hayama, Kanagawa Pref., 4 ˁˁ, 6 ˂˂, NSMT-Cr 5718, 15-V-1978, coll. by M. Takeda .

Shiono-misaki , Kii Penin., Wakayama Pref., 4 ˁˁ, 4 ovig. ˂˂, 1 ˂, NSMT-Cr 5869, 20-VII-1978, coll. by M. Takeda .

Shimama, Tanega-shima I., south of Kyushu, 4 ˁˁ, 1 ovig. ˂, NSMT-Cr 5208, 9-VI-1975, coll. by M. Takeda; Sunosaki, Tanega-shima I., 1 ˁ, 4 ovig. ˂˂, 1 ˂, NSMT-Cr 5190, 14-VI-1975, coll. by M. Takeda.

Remarks. ɹ In Japan, this species is rather commonly found among some kinds of seaweed at the rocky shore and long known as Pilumnopeus indicus (De Man, 1887) since the suggestion by Balss (1933). When Davie (1989) established the genus Benthopanope with the type species, B. estuarius sp. nov. from sub-tidal middy bottoms along the southeast to northwest coasts of Australia, P. indicus was considered to be congeneric with B. estuarius and some additional species. Then, Ho et al. (2000), Ng et al. (2001) and Ng et al. (2017) listed B. indica from Taiwan, but commented that B. indica and Heteropanope pearsei are specifically distinct from each other, and that B. indica from Taiwan should be changed to B. pearsei in due time. Ng et al. (2008) listed both species as valid, but Takeda et al. (2011) recorded this species from the southern Japan Sea as B. pearsei . Sakai (1965) recorded the specimens from Sagami Bay as Pilumnopeus indica after comparison with the type specimens of Heteropanope pearsei which were considered to be quite identical with Pilumnopeus indicus .

Most of the specimens examined during this study are small with the carapace breadth less than 1 cm and the rather rounded contour of the carapace, agreeing well with the colored illustration of Sakai (1939, pl. 62 fig. 4). The shape of the carapace anterolateral margin ( Fig. 3C–D ) is, however, somewhat variable individually and developmentally; the margin continuous with the external orbital angle before the first tooth is not at all developed or posteriorly developed and weakly angulated; in most of the specimens, the first tooth is depressed and more or less lobate, with its outer margin being weakly convex outwards along the general anterolateral curvature, and its obtuse tip is directed forward, but in some and larger specimens, the first tooth is developed to be tubercular and directed obliquely outwards; the second tooth is exposed to the same variation as the first tooth, especially as for the outer margin. In all the specimens, one cheliped is always heavy in both sexes, and the larger cheliped is perfectly smooth and shining.

In the original figure of Heteropanope indica , the carapace anterolateral teeth were figured to be more or less tubercular and weakly curved obliquely forwards, but the transverse ridges on the protogastric and epibranchial ridges may be seemingly strong, but the species identification is followed Patel et al. (2024) who examined the lectotype and additional specimens of Pilumnopeus indicus and the lectotype and paralectotype of P. pearsei , and showed the distinct differences in the carapace shape and anterolateral armatrure of both species.

Distribution. ɹ Japan, Korea, Taiwan and coasts of China.

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).