Leptalpheus denticulatus Anker & Marin, 2009

Anker, Arthur, 2010, New findings of rare or little-known alpheid shrimp genera (Crustacea, Decapoda) in Moorea, French Polynesia, Zootaxa 2403, pp. 23-41 : 38

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.

Figures

FIGURE 9. Leptalpheus pacificus Banner & Banner, 1974, male (CL 7.50 mm) from Moorea, FLMNH UF Arthropoda 16489; A, dorsal view; B, lateral view; C, frontal region, dorsal view; D, uropodal exopod, dorsal view; E, major cheliped in situ, lateral view; E, same, detail of fingers.

FIGURE 10. Leptalpheus denticulatus Anker & Marin, 2009, three specimens from Moorea: A-D, ovigerous female (CL 8.90 mm), FLMNH UF Arthropoda 16463; E, ovigerous female (CL 5.40 mm), FLMNH UF Arthropoda 16532; F, female (CL 4.60 mm), FLMNH UF Arthropoda 16528; A, dorsal view; B, lateral view; C, frontal region, dorsal view; D, major chela, detail of fingers; E, tail fan, dorsal view; F, major cheliped in situ, lateral view.