Wolffogebia Sakai, 1982

Ngoc-Ho, Nguyen, Ngoc-Dung, Duong & Phi-Hung, Tran, 2001, The genus Wolffogebia Sakai, 1982 (Crustacea, Decapoda, Thalassinidea, Upogebiidae) with a new species from Vietnam, Zoosystema 23 (1), pp. 101-108 : 102-103

Genus Wolffogebia Sakai, 1982

Wolffogebia Sakai, 1982: 75 ; 1993: 109. — Ngoc-Ho 1994b: 210.

TYPE SPECIES. — Wolffogebia phuketensis Sakai, 1982 , by designation.

DIAGNOSIS (adapted from Sakai 1993 and Ngoc-Ho 1994b). — Rostrum rounded or convex distally, ventral border unarmed. Anterior region of carapace with dense setae and a slight, non-setose median carina; no longitudinal median groove on rostrum. Anterolateral border of carapace unarmed or with minute spine. Antennular and antennal peduncles unarmed. Mandible with no anteromesial tooth. Maxilliped 1 with large epipod, maxilliped 3 without epipod, maxillipeds 2 and 3 with exopods lacking articulated flagellum. Arthrobranchs with single row of large lamellae on each side of rachis. Pereiopod 1 subcheliform. Telson slightly broader than long, posterior border nearly straight or slightly concave medially.

SPECIES INCLUDED. — Wolffogebia phuketensis Sakai, 1982 ; W. inermis Sakai, 1982 ; W. nhatrangensis n. sp.

REMARKS

The holotype of Wolfogebia obtifrons (ZMH K-30878), an ovigerous female from Port Hedland Australia, was compared to specimens of Upogebia giralia from Queensland, Australia (MNHN Th 1249). As Sakai (1982: 105) previously stated, both lots belong to the same species and share the unusual feature of a pleurobranch on the thoracic segment of pereiopod 5. A minor difference occurs in the shape of the rostrum (see Sakai 1982: fig. 17b; Ngoc-Ho 1994a: fig. 10a) which is more rounded distally in the Queensland material.

Similarities and differences between Upogebia giralia and Wolffogebia species have been discussed in detail (Ngoc-Ho 1994a: 73). Upogebia giralia is similar to Wolffogebia species and especially to the type species, W. phuketensis , in certain aspects, i.e. the absence of a median rostral groove and possession of the unusual combination of characters: unarmed antero-lateral border of carapace with subcheliform pereiopod 1. Nevertheless, it differs in several important features, especially by having maxillipeds 2 and 3 exopods of usual morphology (terminating in an articulated flagellum) and an extra pleurobranch on pereiopod 5. The latter is at present reported in only six upogebiid species and considered of great evolutionary importance.

In this work, Wolffogebia obtifrons Sakai is regarded as a junior synonym of Upogebia giralia Poore & Griffin and set aside from the genus Wolffogebia . It has also been questioned whether Gebicula exigua Alcock, 1901 , a deep-sea species, could be placed within Wolffogebia (Ngoc-Ho 1994b: 210). The holotype, a female captured at 485 m depth, is deposited in the Indian Museum and unavailable for examination at present. Nevertheless, the original figure ( Alcock 1901: fig. 4), in lateral view, shows the anterolateral border of the carapace bearing at least two spines and depicts several spines on the lower border of the antenna as well as on pereiopods 1, 2 and 3, which is in contradiction to all other Wolffogebia species. It seems unlikely that Gebicula exigua belongs to Wolffogebia , but this cannot be known for certain until its holotype is examined.

Most specimens of Upogebia kyusyuensis Yokoya, 1933 are missing and the rest difficult to access (Sakai pers. comm.). Still, considering the original description and figures, Sakai (1993) was probably right to exclude it from Wolffogebia . It differs especially by having a median longitudinal groove on the anterior half of the carapace and the rostrum and by the telson having a deeply concave posterior border.

Specimens of W. phuketensis from Singapore (MNHN Th 1293) and numerous specimens of W. inermis collected from Vietnam in late 1993 and in 1995 were examined. As reported by Ngoc-Ho (1994b), specimens of W. inermis agree well with the description and figures of the holotype ( Sakai 1982: 81) and also with the Australian female examined by Sakai (1993: 109), except for the morphology of maxillipeds ( Sakai 1993: fig. 13A-C). Stained appendages confirm the presence of a large epipod on maxilliped 1 and no articulated flagellum on the exopod of maxillipeds 2 and 3. The small median spine on the posterior border of the telson (see Sakai 1993: fig. 12C) is present in only a few specimens examined.

The new taxon, Wolffogebia nhatrangensis n. sp. can be distinguished from known species of Wolffogebia by having a minute spine on the anterolateral border of the carapace, which is present in all specimens examined. The diagnosis of the genus is amended to accommodate this feature.