Eupontonia nudirostris Marin, 2014

Anker, Arthur & Grave, Sammy De, 2019, Further records of burrow-associated palaemonid shrimps (Decapoda: Palaemonidae), Zootaxa 4612 (1), pp. 145-150 : 145-146

Eupontonia nudirostris Marin, 2014

( Figs. 1 –2)

Material examined. 1 male (pocl 2.2 mm), OUMNH. ZC. 2018-06-01, Solomon Islands, New Georgia, near Munda, Hopei Island , shallow sandflat near seagrass bed, 0.5–1.0 m, in burrow of unidentified echiuran ( Thalassematidae ), suction (yabby) pump, leg. A. Anker, 14.IX.2016 (fcn SOL-107) .

Morphological remarks. Although the present male specimen is morphologically very similar to the female holotype (and only other specimen known to date), some minor differences are notable: (1) the rostrum ( Fig. 1A ) is less deep and less curved downwards, fractionally shorter, reaching to the middle of the second article of the antennular peduncle; (2) the antennal tooth ( Fig. 1A ) is more pronounced and seemingly less separated from the inferior orbital angle than in the illustration of Marin (2014: fig. 2A); (3) the second pereiopod is somewhat unequal in size, with minor ( Fig. 1B ) and major chelae discernible; and (4) the dentition of the fingers of the second pereiopod chela ( Fig. 1B, C ) is more strongly developed, with an additional tooth being present on the dactylus. The previously unknown appendix masculina ( Fig. 1 ) is slightly shorter than the appendix interna, laterally furnished with a sparse series of simple stiff setae.

Colour pattern. The colour pattern of the present specimen (Fig. 2A) is less pronounced in comparison to that of the holotype in Marin (2014: fig. 5). Nevertheless, scattered orange chromatophores are present on the body and legs, whilst orange bands are visible on the second pereiopods, being particularly dense on the fingers of the chelae.

Host. The present specimen was collected from the burrow of an unidentified echiuran ( Thalassematidae ) (Fig 2B), whilst the holotype was collected from the burrow of Listriolobus sp. (also Thalassematidae ), together with an “unidentified Alpheus ” ( Marin 2014), subsequently described as Alpheus echiurophilus Anker, Komai & Marin, 2015 (Anker et al. 2015).

Distribution. Eupontonia nudirostris was previously only known from the holotype, collected in the mangrovefringed intertidal in Nha Trang Bay, Vietnam. The present record from the Solomon Islands considerably enlarges its recorded distribution in the tropical western Pacific, whilst the occurrence in a more seagrass sandflat biotope suggests that the species is not restricted to mangrove environments.

Figures

FIGURE 1. Eupontonia nudirostris Marin, 2014. Male (pocl 2.2) from Hopei Island, Munda, Solomon Islands, OUMNH.ZC.2018- 06-01, A) Carapace, frontal margin; B) Minor (left) second pereiopod, lateral view; C) Major (right) second pereiopod, dorsal view; D) Second pleopod. Scale bar indicates 1 mm (A, D) or 0.5 mm (B, C).