Trizocheles sakaii (Forest, 1987)

Komai, Tomoyuki & Chan, Tin-Yam, 2016, “ Symmetrical ” hermit crabs of the family Pylochelidae (Crustacea: Decapoda: Anomura) collected by the “ BIOPAPUA ” and “ PAPUA NIUGINI ” expeditions in the Papua New Guinea, with descriptions of two new species, Zootaxa 4088 (3), pp. 301-328 : 320-322

Trizocheles sakaii (Forest, 1987)

( Fig. 5 B)

Trizocheles sakaii Forest, 1987a: 189 , figs. 46a–h, 48d, e, 61b, 63d, 64, pls. 5A, B, F, G, 8A, B [type locality: Tosa Bay, Japan]; 1987b: 315, fig. 2.—McLaughlin et al. 2007: 36, unnumbered figs.—Lemaitre et al. 2009: 5.—McLaughlin & Lemaitre 2009: 214.—Komai 2013: 92.

Material examined. BIOPAPUA, stn CP 3691, SE of Manus Island, 02°11’S, 147°18’E, 499–517 m, 29 September 2010, 1 female (sl 6.1 mm), MNHN-IU-2011-3586; stn CP 3692, SE of Manus Island, 02°10’S, 147°19’E, 408–448 m, 29 September 2010, 1 male (sl 6.0 mm), 2 females (sl 2.2, 2.9 mm), MNHN-IU-2011-2784; stn CP 3707, 04°59’S, 145°50’E, 460–466 m, 2 October 2010, 1 male (sl 10.2 mm), MNHN-IU-2011-1947; same data, 1 female (sl 5.6 mm), MNHN-IU-2011-1658; stn DW 3745, off Bougainville Island, 05°33’S, 154°00’E, 369–377 m, 12 October 2010, 2 males (sl 4.1, 4.1 mm), 3 ovigerous females (sl 4.5–5.0 mm), MNHN-IU-2011- 3490; stn DW 3748, off Bougainville Island, 05°37’S, 154°01’E, 398–399 m, 12 October 2010, 3 males (sl 4.9–5.6 mm), 1 female (sl 4.0 mm), 2 ovigerous females (sl 4.8, 5.0 mm), MNHN-IU-2011-5062.

PAPUA NIUGINI, stn CP 3970, W of Karkar Island, Bismarck Sea, 04°39’S, 145°52’E, 573 m, 4 December 2012, 2 females (sl 4.3, 4.3 mm), MNHN-IU-2013-13210; same data, 1 male (sl 5.8 mm), MNHN-IU-2013-14436; stn CP 3978, N of Bagabag Island, Bismarck Sea, 04°49’S, 146°12’E, 456–582 m, 5 December 2012, 7 males (sl 4.6–10.0 mm), 3 females (sl 3.4–7.3 mm), MNHN-IU-2013-14434; stn CP 3979, N of Bagabag Island, 04°44’S, 148°11’E, 540–580 m, 5 December 2012, 2 males (sl 5.1, 9.2 mm), 1 ovigerous female (sl 7.3 mm), MNHN-IU- 2013-14430; same data, 1 female (sl 4.6 mm), MNHN-IU-2013-14438; stn CP 3994, Vitjaz Strait, 06°00’S, 147°35’E, 645–652 m, 9 December 2012, 1 male (sl 5.3 mm), 1 ovigerous female (sl 5.5 mm), MNHN-IU-2013- 14435; stn CP 4006, SE of Tuam Island, Solomon Sea, 06°03’N, 148°08’E, 440–475 m, 11 December 2012, 1 female (sl 5.1 mm), MNHN-IU-2013-14432; stn CP 4009, SE of Tuam Island, 06°04’S, 148°12’E, 550–575 m, 11 December 2012, 1 ovigerous female (sl 4.8 mm), MNHN-IU-2014-12695.

Comparative material. Off Shionomisaki, Kii Peninsula, Japan, 250 m, 15 January 1990, dredge, coll. S. Nagai, 1 male (sl 4.7 mm), CBM-ZC 1084; same locality, 200 m, 19 December 1992, dredge, coll. S. Nagai, 1 ovigerous female (sl 5.1 mm), CBM-ZC 1182; same locality, 250 m, 22 March 1992, dredge, coll. S. Nagai, 1 female (sl 3.9 mm), CBM-ZC 1184; same locality, 300 m, October 1996, dredge, coll. S. Nagai, 1 male (sl 3.7 mm), 1 female (sl 4.0 mm), CBM-ZC 3561.

TAIWAN 2000, stn DW 56, 24°29.8’N, 122°12.6’E, 438–539 m, 4 August 2000, 2 males (cl 4.3, 6.6 mm), 1 female (cl 4.2 mm), NTOU. TAIWAN 2004, stn CP 269, 24°30.55’N, 122º05.78’E, 2 September 2004, 397–399 m, 2 ovigerous females (sl 4.9, 5.7 mm), NTOU.

Size. Largest male sl 10.2 mm, largest female sl 7.3 mm, ovigerous females sl 4.8–7.3 mm.

Colour in life. Shield, ocular peduncles, antennular peduncles, chelipeds and ambulatory legs generally orange, posterior carapace and pleon paler; ocular acicles and antennal peduncles whitish; meri of chelipeds and ambulatory legs each with white transverse band distally ( Fig. 5 B).

Distribution. Previously known from Japan and Taiwan, at depths of 200–539 m. The present material greatly extends the geographical range of this species to the south; in waters around Papua New Guinea, this species occurs at depths of 369–652 m.

Habitat. Scaphopod (tusk) shells.

Remarks. The present specimens are identified with Trizocheles sakaii because of the following characteristics: palms of chelipeds armed with two to four rows of spines; carpi of chelipeds with stridulating rods or tubercles; propodi of second pereopods moderately stout (3.6 times as long as wide or less), armed only with dorsodistal spine, otherwise unarmed. Comparison with the material from Japan and Taiwan failed to detect significant morphological differences from the Papua New Guinea specimens, although there is a wide geographical gap between Papua New Guinea and the Japanese Archipelago. With regard to the living coloration, minor differences are seen: the male specimen from stn DW 3745 (MNHN-IU-2011-3490) has white distal bands on the meri of the chelipeds and ambulatory legs ( Fig. 5 B), whereas such white bands are not seen on the meri of the chelipeds in the specimen from Taiwan (McLaughlin et al. 2007: 36, unnumbered fig.).

Forest (1987a) attributed all records of Pylocheles spinosus from Japanese waters (Ortmann 1892; Balss 1913; Yokoya 1933; Miyake 1978, 1982) to Trizocheles sakaii , and this was followed by McLaughlin & Lemaitre (2009). Komai (2013) clarified this by noting that Ortmann’s (1892) specimen actually represented T. albatrossi instead of T. sakaii , and that two species, T. albatrossi and Pomatocheles jeffreisi , were mixed up in the material identified as Pylocheles spinosus by Miyake (1978).

Figures

FIGURE 5. A, Trizocheles manningi Forest, 1987, entire animal in dorsal view, BIOPAPUA, stn DW 3732, ovigerous female (sl 4.6 mm), MNHN-IU- 2011 - 1039; B, Trizocheles sakaii Forest, 1987, stn DW 3745, males (sl 4.1 mm), MNHN-IU- 2011 - 3490.