Pagurixus tweediei ( Forest, 1956 )

Komai, Tomoyuki, Rahayu, Dwi Listyo & Fujita, Yoshihisa, 2021, Hermit crabs of the family Paguridae (Crustacea: Decapoda: Anomura) from Christmas and Cocos (Keeling) Islands, Indian Ocean Territory of Australia, with descriptions of three new species and reappraisal of the genus Kumepagurus Komai & Osawa, 2012, Raffles Bulletin of Zoology 69, pp. 378-402 : 398

Pagurixus tweediei ( Forest, 1956)

( Fig. 12A )

Eupagurus (Pagurixus) tweediei Forest, 1956: 50 , pl. 4 [type locality: Cocos (Keeling) Islands].

Pagurus (Pagurixus) tweediei – Dechancé, 1964: 38; Ball & Haig, 1972: 103; Lewinsohn, 1982: 58.

Pagurixus tweediei – Komai & Osawa, 2006: 25 , figs. 8–11, 44B, 47; Osawa et al., 2013: 357 , fig. 2D.

Material examined. CHRISTMAS ISLAND. QM W29572, 1 male (sl 3.4 mm), CI-D03-2010, Coconut Point , 10°24.741′S, 105°41.868′E, 27 January 2010 ; ZRC 2021.0640 , 1 male (sl 3.6 mm; photo), CI-D05-2011, West White Cave , off West White Beach, 1–12.3 m, 10°27.733′S, 105°35.054′E, 25 March 2011 ; ZRC 2021.0641 , 1 male (sl 2.0 mm), Thunderdome Cave , Christmas Island, 10°27.906′S, 105°36.465′E, 3–16.6 m, 30 March 2011 .

COCOS (KEELING) ISLANDS. ZRC 2021.0642 , 1 ovigerous female (sl 3.5 mm; photo), CK18, the Rip , SW of Direction Island, 12°05.675′E, 96°53.175′E, 5.7 m, 22 March 2011 .

Distribution. Previously known with certainty from Cocos (Keeling) Islands (type locality); Japan (Ogasawara Islands and Ryukyu Islands), Mariana Islands ( Guam), and French Polynesia (Society Islands) in the western Pacific Ocean; intertidal to 91.3 m ( Komai & Osawa, 2006; Osawa et al., 2013). Newly recorded from Christmas Island, at depths of 1–16.6 m.

Remarks. Pagurixus tweediei was originally described on the basis of material from Cocos (Keeling) Islands ( Forest, 1956). Komai & Osawa (2006) reexamined the two syntypes, and clarified that P. cf. tweediei of McLaughlin & Haig (1984) might actually represent P. carinimaus instead.

The present specimens, including the topotypic specimen from Cocos (Keeling) Islands, differ from specimens from the Ryukyu Islands ( Japan) and Society Islands ( French Polynesia), referred to as P. tweediei by Komai & Osawa (2006) and Osawa et al. (2013), in the lack of proximal and distal white rings on the propodi of the ambulatory legs ( Fig. 12A versus Komai & Osawa, 2006: fig. 44B; Osawa et al., 2013: fig. 2D), although they are morphologically similar to one another. In this colour pattern of the ambulatory legs, the present specimens are rather similar to P. formosus Komai, 2010 (cf. Osawa et al., 2013: fig. 2B, C), but seem to differ from the latter taxon in the possession of distinct spines on the dorsolateral and dorsomesial margins of the left cheliped carpus (in P. formosus , there are only rows of small tubercles or granules there; Komai, 2010; Osawa et al., 2013). Molecular genetic analyses would be advisable to fully clarify the status of the western Pacific populations referred to as P. tweediei and of P. formosus .

Morgan (1992) recorded P. tweediei from Christmas and Cocos (Keeling) Islands, but his identification seems to have been based on McLaughlin & Haig’s (1984) account. Komai & Osawa (2006) argued that Morgan’s specimens did not represent the true P. tweediei , although the identity was not established.

Figures

Fig. 12. Habitus in dorsal view, showing living colouration. A, Pagurixus tweediei (Forest, 1956), ZRC 2021.0640, male (sl 3.6 mm); B, Pylopaguropsis bellula Osawa & Okuno, 2007, ZRC 2021.0643, female (sl 3.0 mm); C, Pylopaguropsis keijii McLaughlin & Haig, 1989, ZRC 2021.0645. Photographs by LKCNHM.