Athanas cf. dentirostris Anker, Jeng & Chan, 2001

Anker, Arthur, 2023, Alpheid shrimps of the genera Athanas Leach, 1814, Athanopsis Coutière, 1897 and Pseudathanas Bruce, 1983 of the coasts of the Arabian Peninsula (Malacostraca: Decapoda: Caridea), Zootaxa 5383 (2), pp. 179-215 : 187-189

Athanas cf. dentirostris Anker, Jeng & Chan, 2001

( Fig. 4 )

Athanas dentirostris Anker et al. 2001: 1049 , figs. 1–3.

Material examined. 1 male (cl 4.4 mm), FLMNH UF 71432 , Oman, Masirah Island , channel side, Dafiyat, 20°35’15.1”N / 58°49’36.9”E, intertidal and shallow subtidal sandflat with patches of coral rubble, rocks and seagrass, depth at low tide less than 0.5 m, suction pump, in burrow, leg. A. Anker, 08.11.2022 [fcn BOMAN-13044] ; 1 male (cl 3.5 mm), 1 ovig. female (cl 4.0 mm), FLMNH UF 71419 , same collection data as for previous specimen [fcn BOMAN-13052]; 1 ovig. female (cl 3.6 mm), FLMNH UF 71434 , same collection data as for previous specimens [fcn BOMAN-13051] ; 3 females (incl. 2 ovig., cl not measured, all missing major chelipeds), FLMNH UF 71438 , same collection data as for previous specimens [fcn BOMAN-13053] ; 1 male (cl 3.6 mm, missing both chelipeds), FLMNH UF 71433 , same collection locality as for previous specimens, leg. A. Anker, 13.11.2022 [fcn BOMAN-13817]; 1 ovig. female (cl 4.7 mm), FLMNH UF 71415 , same collection data as for previous specimen [fcn BOMAN-13826]; 1 ovig. female (cl 4.6 mm), FLMNH UF 71416 , same collection data as for previous specimen [fcn BOMAN-13825] ; 4 females (incl. 3 ovig., all but one without chelipeds), FLMNH UF 71436 , same collection data as for previous specimen [fcn BOMAN-13827] ; 1 male (cl 5.0 mm), FLMNH UF 71430 , same collection data as for previous specimen [fcn BOMAN-13824] ; 1 male (cl 5.0 mm), FLMNH UF 71431 , same collection data as for previous specimens [fcn BOMAN-13837] ; 1 male (cl 4.7 mm), 2 ovig. females (cl 3.9 mm, 4.0 mm, former missing both chelipeds), FLMNH UF 71413 , same collection data as for previous specimens [fcn BOMAN-13814] ; 1 male (cl 5.3 mm), FLMNH UF 71421 , same collection data as for previous specimens [fcn BOMAN-13823] ; 1 male (cl 5.1 mm), FLMNH UF 71439 , same collection locality as for previous specimens, leg. A. Anker, 15.11.2022 [fcn BOMAN-14056] ; 1 male (cl 4.8 mm), FLMNH UF 71435 , same collection data as for previous specimen [fcn BOMAN-14062] ; 1 male (cl 2.9 mm), FLMNH UF 71420 , same collection data as for previous specimen [fcn BOMAN-14053] .

Description. For description and illustrations of A. dentirostris see Anker et al. (2001); some taxonomic remarks on the Omani material tentatively identified herein as A. cf. dentirostris are provided below, including description and illustration of the shrimps’ conspicuous colour pattern ( Fig. 4 ).

Colour in life. Background translucent whitish; carapace and pleon irregularly speckled with numerous, large, dark red dots, each composed of several red chromatophores; some white chromatophores interspersed among red ones, forming large star-shaped patches; dorsal surface of carapace and pleon with larger transverse bands formed by white chromatophores, most conspicuous on third and fourth pleonites; telson with proximal half translucent with red dots and distal half conspicuously white; antennular and antennal peduncles mostly covered with red dots, flagella with scarce red dots proximally, colourless distally; third maxillipeds and second pereiopods whitish with red dots; chelipeds hyaline white with patches of red dots, denser on merus and chelae, carpus additionally with some white patches, fingers ivory white; remaining pereiopods mostly colourless; uropods with endopod and proximal and central portion of exopod translucent with red dots, distal portion with conspicuous white patch ( Fig. 4 ).

Distribution. Vietnam: Cua Luc (type locality of A. dentirostris ) ( Anker et al. 2001); possibly Oman: Masirah Island ( A. cf. dentirostris ) (present study).

Ecology. All specimens of A. cf. dentirostris were collected from burrows in the sandy-muddy intertidal or the adjacent shallow subtidal (less than 1 m), with large patches of seagrass. The syntopic infauna, which is still being studied, included large snapping shrimps ( Alpheus spp. ) and upogebiid mud-shrimps. At least two specimens of A. cf. dentirostris were collected from burrows together with the snapping shrimp Alpheus cf. lobidens De Haan, 1849 , in the muddier part of the intertidal. The holotype of A. dentirostris was collected, according to the specimen label, together with Austinogebia aff. takaoensis (Sakai & Türkay, 1995) “in fine mud and grit” (Anker et al. 2021).

Remarks. Athanas dentirostris is presently known with certainty only from the holotype from northern Vietnam ( Anker et al. 2001). The abundant Omani material may well be conspecific with A. dentirostris or represent a closely related species. The dorsal teeth of the rostrum appear to be more pronounced in the Omani material of A. cf. dentirostris compared to those of the holotype of A. dentirostris . In fact, in some Omani specimens, the distal-most teeth are very conspicuous and more closely positioned to each other, compared to the smaller and more widely spaced teeth of the holotype. Furthermore, the armature of the finger cutting edges of the major chela of the Omani male specimens appears to be stronger than in the Vietnamese male holotype, with one some teeth also present on the dactylus. The cutting edge of the major chela dactylus was illustrated as unarmed in Anker et al. (2021: fig. 3c); however, it must be noted that the cutting edges and adjacent areas of both fingers are largely concealed by a dense setal cover. In all other important details, the Omani specimens seem to correspond well to the holotype of A. dentirostris . Since no intraspecific variation can be presently assessed for the Vietnamese population of A. dentirostris and considering the significantly smaller size of the holotype male (cl 3.8 mm) compared to the largest males from Masirah Island (cl 5.0– 5.2 mm), which may explain differences in the cheliped armature, the author prefers to report the Omani material as A. cf. dentirostris . The collection of more material of A. dentirostris in Vietnam and across South-East Asia is needed to solve the identity of A. cf. dentirostris , which may also involve comparisons of DNA sequences and colour patterns.

Figures

FIGURE 4. Athanas cf. dentirostris Anker, Jeng & Chan, 2001, male (cl 4.4 mm) from Masirah Island, Oman (FLMNH UF 71432); a, shrimp in life, lateral (right side); b, same, lateral (left side); c, same, dorsal. Photographs by the author.