Pagurixus formosus Komai, 2010

Osawa, Masayuki, Kawai, Takashi & Sakamaki, Takashi, 2013, New records of Pagurixus Melin, 1939 (Crustacea: Decapoda: Paguridae) from the Ryukyu Islands, southwestern Japan, with description of a new species, Zootaxa 3669 (3), pp. 350-366 : 356

Pagurixus formosus Komai, 2010

( Figs 2B, C , 3F )

[New Japanese name: Chairo-himehonyardokari]

Pagurixus formosus Komai, 2010: 1306 , figs 17–19 [type locality: Shiangianwan, Kenting, Pingtung County, southern Taiwan, 3–8 m].— McLaughlin et al. 2010: 31 (list).— Komai & Rahayu 2013: 134 .

Material examined. Kume-jima: “KUMEJIMA 2009” stn Dive 28 (Oyako-iwa), 26°17.5´N, 126°47.9´E, 0–20 m, 17 Nov. 2009, 1 male (sl 2.7 mm), RUMF-ZC 2334 . Okinawa-jima: Benoki, Kunigami, intertidal, 30 Apr. 2010, coll. M. Osawa, 1 male (sl 2.9 mm), RUMF-ZC 2335 .

Coloration in life. Carapace whitish; shield with several brown patches: 2 pairs on lateral parts, 1 pair on anterior submedian part, and 1 on posterior median part; posterior carapace with numerous, small red spots and 1 pair of longitudinal brown lines on submedian part. Ocular peduncles translucent, with brown tinge proximally and brown marking at base of cornea; ocular acicles brown proximally. Antennular peduncles with subdistal brown band on penultimate segment; ultimate segment entirely dark brown; dorsal flagella pale blue proximally, turning pale red distally. Antennal peduncle generally translucent; second and third segments each with large brown marking; fourth segment with subdistal brown ring; fifth segment marginally brown; flagellum generally translucent, dark brown on margins. Right and left chelipeds brown; meri each with 2 white bands on median and subdistal parts, median band on right merus either interrupted or uninterrupted on dorsal surface. Ambulatory legs brown; meri each with 2 irregular, white bands on median and subdistal parts, median band of each third pereopod interrupted on midline. See Fig. 2B, C .

Distribution. Previously known only from Kenting, Pingtung County in the southern Taiwan, and Panglao Island, the Philippines; 2–8 m ( Komai & Rahayu 2013). Now also recorded from Japan, Okinawa-jima and Kumejima in the central Ryukyus; intertidal to 20 m.

Habitat. Rocky reefs, under rocks and dead coral rubble.

Remarks. Komai (2010) described the coloration of P. formosus based on preserved material. The coloration of fresh specimens agrees well with Komai’s (2010) description, particularly in the band pattern of the chelipeds and ambulatory legs. The morphological characters of the present Ryukyu specimens also agree well with the original description, although the dorsomesial margin of the carpus of the left cheliped has a row of small spines rather than tubercles. The male from Kume-jima (RUMF-ZC 2334) has a relatively larger left cheliped ( Fig. 2C ) and more elongate and slender dactyli of the ambulatory legs compared to the holotype ( Komai 2010: fig. 17C–F). The dactylus of the third pereopod is slightly longer than the propodus and about seven times length of its width ( Fig. 3F ).

As discussed by Komai (2010), P. formosus appears closest to P. tweediei in both morphology and coloration. The former species is also closely similar to P. nomurai in the color pattern of the entire body, although the color of the chelipeds and ambulatory legs may differ between the two species. The pereopods are generally brown in P. formosus , instead of bluish gray or bluish brown in P. nomurai . Pagurixus formosus is readily distinguished from P. nomurai in morphology, particularly in the corneas not strongly dilated and the carpus of the left cheliped and dactyli of the ambulatory legs being much stouter.

Figures

FIGURE 2. Entire animal, dorsal view. A, Pagurixus carinimanus Komai & Osawa, 2006, female (sl 1.7 mm), stn K 1-1, Kuchino-shima, RUMF-ZC 2328 (left cheliped and left second and third pereopods missing); B, Pagurixus formosus Komai, 2010, male (sl 2.9 mm), Benoki, Kunigami, Okinawa-jima, RUMF-ZC 2335; C, Pagurixus formosus Komai, 2010, male (sl 2.7 mm), “KUMEJIMA 2009” stn Dive 28, Kume-jima, RUMF-ZC 2334; D, Pagurixus tweediei (Forest, 1956), male (sl 2.5 mm), Zatsun, Kunigami, Okinawa-jima Island, RUMF-ZC 2342. (third pereopods missing); E, Pagurixus pseliophorus Komai & Osawa, 2006, male (sl 2.6 mm), Zatsun, Kunigami, Okinawa-jima, RUMF-ZC 2339 (right third pereopod missing); F, Pagurixus pseliophorus Komai & Osawa, 2006, ovig. female (sl 2.7 mm), Benoki, Kunigami, Okinawa-jima, RUMF-ZC 2336.

FIGURE 3. Pagurixus acanthocarpus Komai & Okuno, 2009, male (sl 1.8 mm), stn Sumiyoshi 2, Tanega-shima, RUMF-ZC 2324 (A). Pagurixus fasciatus Komai & Myorin, 2005, male (sl 1.7 mm), stn Sumiyoshi 2, Tanega-shima, RUMF-ZC 2331 (B, C); female (sl 1.4 mm), same data, RUMF-ZC 2331 (D, E). Pagurixus formosus Komai, 2010, male (sl 2.7 mm), “KUMEJIMA 2009” stn Dive 28, Kume-jima, RUMF-ZC 2334 (F). A, coxa of right fifth pereopod, ventral view; B, D, right second pereopod, mesial view (setae omitted); C, E, left second pereopod, mesial view (setae omitted); F, left third pereopod, dactylus and propodus, lateral view (setae omitted). Scales: 0.5 mm.