Pagurapseudopsis gracilipes Shiino, 1963

Bamber, Roger N, Chatterjee, Tapas & Marshall, David J, 2012, Inshore apseudomorph tanaidaceans (Crustacea: Peracarida) from Brunei: new records and new species, Zootaxa 3520, pp. 71-88 : 85-87

Pagurapseudopsis gracilipes Shiino, 1963

Pagurapseudopsis gracilipes Shiino, 1963: 492 –500, figs 21–23.

Material examined: 13 (dissected); 3ƤƤ (1 brooding, one with oostegites), 2 subadults ( BMNH.2012.1085–1090), Brunei Darussalam, 0 4°40.5ʹN 114°26.5ʹE, sand, 2–8 m depth, March 2009. 1 brooding Ƥ ( BMNH.2012.1091), Sungai Besar, Sungai Brunei Estuary and Bay, Brunei Darussalam, 4º56'N, 115º1'E, mud flat and algae covering the pneumatophores of Avicennia marina , coll T Chatterjee and David J Marshall, 10 March 2011.

Description of female cheliped ( Fig. 8 ): All articles densely clothed in fine simple setae. Basis as long as wide, almost circular, with short attachment peduncle; exopod of three articles, proximal article fused to basis, distal article with two plumose setae. Merus subrectangular, with conspicuous blunt mid-ventral apophysis, one dorsodistal slender spine. Carpus 2.3 times as long as wide, ventral margin with numerous tubercle-like apophyses, dorsal margin crenulate proximally, and with blunt apophysis distally. Propodus robust, 1.3 times as long as wide, with subdistal spine denticulate in its distal half (comb-row?); fixed finger half as long as palm of chela, cutting edge with mid/proximal invagination, one stouter seta distal to this, and row of about ten curved spinules. Dactylus cutting-edge with submarginal setules, tooth-like apophysis in proximal half, and row of about eight curved spinules distal to this.

Remarks. This genus is of well-calcified, brittle animals, with a propensity for detachment of the chelipeds. The brooding females and the female with oostegites all had an attached cheliped, of a form distinctly different from that shown by Shiino (1963) for the type, while a detached cheliped in the sample was of the form figured for the type. The other described species of this genus do show sexual dimorphism in the chelipeds.

Barnard (1935) records one male and one “immature” female for his P. gymnophobia (as Apseudes gymnophobia ), but the latter with oostegites; his figured cheliped of the male does not have the rounded propodus of that of the female of P. gracilipes , but is more consistent with the cheliped attributed herein to the male P. gracilipes ; he makes no mention of the female cheliped. Bäcescu (1978) alluded to some sexual dimorphism in the chelipeds of his P. iranica , but the female chelipeds were damaged. Bäcescu (1981) described P. ceylonica (as P. gymnophobia ceylonica ) as having a massive cheliped in the female (his figure 1H showing a stout propodus), and a “robust” cheliped “1/3 thicker than those of the Ƥ”, but unfigured, in the male. Angsupanich (2001) described as new P. thailandica , the female cheliped having a broader (although not rounded) propodus and a distally-wider carpus (the male having a conspicuous proximoventral apophysis unique to this species).

While it might be considered that this species shows heterochely, the attached female chelipeds in the present material were both right and left, and it appears that what Shiino (1963) figured, as well as the detached cheliped in the present material, was from a male. Shiino (ibid.) referred to all of his specimens as females, but without oostegites or brood pouches, so the presence of a male is not unlikely. The female cheliped is therefore figured herein for the first time, being somewhat more compact than that of the male, and with a carpus widening distally, and a much rounder propodus. The exopodite, as that of the first pereopod, is three-articled, not two-articled as suggested by Shiino (ibid.), but the proximal article is fused to the basis.

The present species is imediately distinguished from its congeners in having a large, blunt, dorsodistal apophysis on the basis of pereopod 1. The types (and only previous records) were from Nha-Trang Bay on the coast of South Vietnam during the Naga Expedition ( Shiino 1963). The Brunei specimens are of a similar size to the type (6.7 mm), adults ranging from 6.75 to 7.0 mm body length.

Pagurapseudopsis gracilipes is a further example of a commonality of tanaidacean fauna between the waters of Brunei and of Vietnam, as found for Hainanius nigrifrons , Apseudes gallardoi and A. nagae (see Introduction, above).

Figures

FIGURE 8. Pagurapseudopsis gracilipes, female cheliped. Scale line = 0.5 mm.