Laomenes amboinensis De Man 1888

Laomenes amboinensis (De Man, 1888)

(Figs. 1–6)

Anchistus amboinensis De Man 1888: 546, pl. 22a: fig.2 [type locality: Ambon, Indonesia]. Periclimenes amboinensis. — Bruce 1983: 874, 898, 899, figs. 1–3, 7E; 1992: 66, figs. 17, 18. Laomenes amboinensis. — Okuno & Fujita 2007: 117, fig. 1.

Material. Vietnam, Nhatrang Bay: 1 ovigerous female (pcl. 3.2 mm), 1 male (pcl. 2.8 mm) (ZMMU), Mun Island, 15 m, on crinoid Oxycomanthus sp., 20.vi.2006, coll. I. Marin; 1 ovigerous female (pcl. 4.4 mm) (ZMMU), Nok Island, 15 m, on crinoid Oxycomanthus bennetti, 7.vii.2006, coll. Marin; 1 ovigerous female (pcl. 4.2 mm), 1 male (pcl. 3.0 mm) (ZMMU), Nok Island, 15–20 m, on Oxycomanthus bennetti, 7.vii.2006, coll. Marin; 1 ovigerous female (pcl. 4.0 mm), 1 male (pcl. 2.5 mm) (ZMMU), Nok Island, 15 m, on Oxycomanthus bennetti, 12.vii.2006, coll. Marin; 1 ovigerous female (pcl. 5.5 mm), 1 male (pcl. 4.0 mm), 1 juv. (ZMMU), Nok Island, 15 m, on Oxycomanthus bennetti, 12.vii.2006, coll. Marin.

Diagnosis. Carapace swollen, smooth, with antennal and hepatic teeth (Fig. 1 A); hepatic tooth triangular, larger than antennal (Fig. 2 A). Rostrum long, slender and straight, with well developed dorsal carina bearing 6 or 7 conspicuous teeth, ventral carina convex, bearing 1 or 2 teeth distally; lateral lamina feebly developed, forming proximally well developed surpaocular teeth (Fig. 2 A, B). Orbit well developed, inferior orbital angle produced, distally rounded. Abdominal somites smooth; pleura of abdominal somites I–V rounded ventrally (Fig. 1 A). Telson about 3 times as long as wide in proximal part (Fig. 4 I), gradually narrowing, with 2 pairs of medium submarginal dorsal spines situated at 0.5 and 0.7 of telson length (Fig. 4 J). Eyes large and well developed, central cornea with well marked stout and blunt central papilla (Fig. 2 C). Antennule well developed (Fig. 2 D); basal segment about twice longer than wide, with acute distolateral tooth at it distolateral angle, without medial projection between the tooth and lateral margin of the intermediate segment (Fig. 2 E); submarginal ventral tooth distinct, situated near the medial border of basal segment. Epistomial horns large and sharp (Fig. 2 G). Mandible robust (Fig. 3 A, B), without palp; incisor process well developed, broad, with 1large and 8 or 9 small terminal teeth (Fig. 3 D); molar process well developed, robust, with stout sharp teeth distally (Fig. 3 C). Maxillule normal (Fig. 3 E), with well developed bilobed palp; upper lacinia slightly curved, flaring distally, with strong setae distally; lower lacinia slender, tapering distally, bearing strong sharp simple setae. Pereiopod I (Fig. 4 A) normal and slender; coxal segment with distinct curved lobe distoventrally; carpus slender, considerably flaring distally; palm subcylindrical, about twice longer than wide; dactylus and fixed finger robust and straight, cutting edges entire, tips simple, non-spatulated. Pereiopod II equal in size and shape in females (Fig. 4 B) and slightly dissimilar in males (Fig. 5 B, D); segments robust; ischium about twice longer than wide; merus with straight margins, about 4 times longer than maximal width; carpus as long as maximal width, flared distally, distoventral margin with well marked notch (Fig. 4 C, D); palm cylindrical, about 3 times as long as maximal width; fingers slender and straight, about 7 times as long as wide, cutting edge entire with 6–8 small triangular teeth along its length, with acute, curved tips (Fig. 4 E). Pereiopod III slender, with segments unarmed; propodus bearing 3 or 4 distoventral spines and several rows of long slender setae along distoventral margin (Fig. 4 F); dactylus (Fig. Fig. 4 H) robust, as long as maximal width, with well developed long, acute and curved unguis, well developed accessory tooth and a tuft of long simple setae at the middle of dactylus. Pereiopods III–V similar. Appendix interna in males is slightly longer than the appendix masculina, with numerous subterminal cincinnuli. Appendix masculina bears 3 long terminal setae and 3 well developed spines along lateral margin.

Coloration. Females are generally brighter than males (Fig. 6 A–F, I). General coloration of the body of females varies from grey to yellow always, related to the coloration of the crinoid host (Fig. 6 A–H). Distal part of carapace, rostrum, eyestalks, antennule and antenna as well as pereiopods I–V, telson and uropods are always lighter than general body varying from white to light yellow (Fig. 6 A–C). Carapace with 2 longitudinal bands laterally; 4 bands cross the carapace dorsally, not reaching the middle of carapace laterally (Fig. 6 A); bands are lighter than body, usually white or light yellow (Fig. 6 C). Abdomen with transverse bands continuing to pleura and edging them (Fig. 6 C). Males are generally transparent with distal part of carapace, rostrum, eyestalks, antennule, antenna, pereiopods I–V, telson and uropods white or yellow (Fig. 6 I).

Remarks. The current specimens are clearly similar to the specimens of this species described previously (Holthuis 1952; Bruce 1983; Okuno & Fujita 2006). The species can be easily identified by moderately slen- der rostrum, slender fingers of pereiopod II, the presence of several rows of setae along distoventral margin of propodus of pereiopod III and distinguishing color pattern. The diagnostic features in coloration are the presence of 4 transverse light bands on carapace dorsally and edging pleura of abdomen.

Hosts. All specimens from Nhatrang Bay, Vietnam were collected from the comasterid crinoid Oxycomanthus bennetti (Müller, 1841) (Crinoidea: Comasteridae) (Fig. 34 C). Previous records from Capillaster multiradiatus (Linnaeus, 1758), Comantheria briareus (Bell, 1882), Comantheria cf. rotula A. H. Clark, 1912, Comaster nobilis (Carpenter, 1884), Comanthus parvicirrus Müller, 1841, Comanthus samoanus A. H. Clark, 1909 and Himerometra magnispinna A. H. Clark, 1908 (see Bruce 1981, 1982, 1983, 1992; Zmarzly 1984; Okuno & Fujita 2007) possibly refer to undescribed species of the “ L. amboinensis ” species group. For example, Comantheria (Comanthus) briareus is recorded as the host for new species described below as Laomenes pardus sp. nov. (see below).

Distribution. The species is known from Vietnam, Indonesia, Philippines, Japan, Western Australia (Bruce 1968, 1983; Fujita & Baba 1999; Marin & Savinkin 2007). Photos published on the world-wide-web (Marin, pers. observ.) show a wider distribution of the species in the Indo-West and Central Pacific from the Red Sea and east coast of Africa east to the Solomon Islands, New Caledonia, Vanuatu, French Polynesia and north to Japan.