Leptalpheus denticulatus Anker & Marin, 2009

Figure 10

Leptalpheus denticulatus Anker & Marin 2009: 92, figs. 1–6, 7a, b, 8.

Material examined. French Polynesia, Society Islands. 1 ovigerous female (CL 8.90 mm), FLMNH UF Arthropoda 16463, Moorea, lagoon near Nihimaru River estuary, near-shore sand flat with some rocks, algae, holothurians ( Holothuria atra) from burrow, suction pump, depth: 0.5–1 m, coll. A. Anker, 17.XI.2008 [fcn BMOO-5519]; 1 female (CL 4.60 mm), FLMNH UF Arthropoda 16528, Moorea, lagoon, between Papetoai and Hotel Intercontinental, near-shore sand flat with intense burrowing activity, silt and sand, mounds, holothurians ( Holothuria atra), from burrow, suction pump, depth: 0.3–0.6 m, coll. A. Anker, 23.XI.2008 [fcn BMOO-5636]; ovigerous female (CL 5.40 mm), FLMNH UF Arthropoda 16532, same collection data as for previous specimen, fcn 5641; 1 male (CL 4.90 mm), 1 female (CL 7.00 mm), 1 juvenile (CL not determined), FLMNH UF Arthropoda 16526, same collection data as for previous specimens [BMOO fcn 5634, 5635, 5633].

Description. See Anker & Marin (2009).

Colour pattern. Uniform pinkish, speckled with reddish chromatophores (Fig. 10), more intense on antennular peduncles and tail fan (Fig. 10 C, D), and in large individuals forming diffuse bands on abdomen (Fig. 10 A, B; see also Anker & Marin 2009, fig. 8); walking legs mostly colourless, major chela hyalinewhitish, with a few red chromatophores on palm (Fig. 10 F).

Type locality. Nhatrang Bay, Vietnam.

Ecology. All Moorea specimens were collected on shallow near-shore sand flats, at depths ranging from 0.3 to 1 m, from burrows of unknown, presumably callianassid, hosts.

Distribution. Nhatrang, Vietnam; Panglao, the Philippines; Viti Levu, Fiji (Anker & Marin 2009); the present report extends its range eastwards to Moorea, French Polynesia .

Remarks. Moorea is presently the only locality where L. denticulatus is known to occur sympatrically with L. pacificus . These two species are very closely related (Anker & Marin 2009), but as mentioned above, L. denticulatus may be distinguished from L. pacificus by the presence of a small tooth on the mesial emargination of the uropodal diaeresis (cf. Fig. 9 D, 10E) and the presence of numerous red chromatophores that are evenly scattered over the body and together provide a uniform pinkish-reddish colour, more intense on the antennular peduncles (Figs. 9 A–C, 10A–C). Interestingly, all specimens of L. denticulatus were collected from burrows near a small estuary or in very shallow silt-covered parts of the inshore lagoon, whereas L. pacificus was collected from burrows in fine white sand at some distance from the main coast, for instance near the Motu Tiahura – Moorea channel, where water is cleaner and more dynamic, indicating a possible ecological niche separation between these two species.