Periclimenes tonga ( Bruce, 1990 )

Ďuriš, Zdeněk, 2010, Periclimenes laevimanus sp. nov. from Vietnam, with a review of the Periclimenes granulimanus species group (Crustacea: Decapoda: Palaemonidae: Pontoniinae) *, Zootaxa 2372 (1), pp. 106-125 : 121

publication ID	https://doi.org/ 10.11646/zootaxa.2372.1.12
persistent identifier	https://treatment.plazi.org/id/03FC7D16-FFB0-FF8F-61AB-B7AA7CC42E37
treatment provided by	Felipe
scientific name	Periclimenes tonga ( Bruce, 1990 )
status

Treatment

Periclimenes tonga ( Bruce, 1990) View in CoL

Periclimenes tonga Bruce, 1990: 23 View in CoL , Figs. 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 . — Chace & Bruce 1993: 60.

Type material. Ov. female holotype, CL 3.7 mm, CAS: IZ 060144 (not examined) .

Remarks. The species has been regarded ( Bruce 2008) as belonging to the Periclimenes aesopius (= holthuisi) group but most characters, e.g. general shape of the body and appendages, proportions and length of the chelipeds, and shape of the major second pereiopod fingers, demonstrate its closer affinity to the Periclimenes granulimanus species group (see Discussion). The species, however, differs from the other species by the ventral shape of the rostrum, which is obtusely angulate at the posterior fourth of its length, similarly to the Atlantic species: Periclimenes paivai Chace, 1969 (also a scyphozoan-associated shrimp and representative of the Atlantic Periclimenes iridescens -species group, see Martínez-Mayén & Román- Contreras 2006) and Urocaris longicaudata Stimpson, 1860 . Both these species can be easily distinguished from P. tonga by the absence of the antennal spine ( Holthuis 1951; Chace 1969).

Based on the original description of P. tonga , the following distinctions are the most important (cf. Bruce 1990): (1) The epigastric spine is lacking. Such character cannot be a stable character of generic value as it may be lacking in distinct species, e.g. P. longicarpus Bruce & Svoboda, 1983 from the P. aesopius species group, other members of which bear the spine ( Bruce 1978, 2008; Okuno 2002), or within a single species, e.g. in some specimens of P. laevimanus sp. nov. ( Table 1) or P. nomadophila (see Berggren 1994). (2) The first pereiopod coxa bears a distinct, produced, distoventral setose process that is indistinct in other species of the P. granulimanus group, but is well-developed in P. incertus Borradaile, 1915 (see Kemp 1922: 148, Fig. 17a, as P. impar ), and is lacking in P. tonga . (3) The first pereiopod chela is widely gaping between the fingers. (4) The prehensile mechanism of the distal propod of walking legs is not apparent and the walking dactyli are less curved than in other species of the P. granulimanus group; the distoventral propodal spines are, however, long and slender, at least in the fifth pereiopods ( Bruce 1990: Fig. 5E View FIGURE 5 ), and closely set on the distal fifth of the segment. (5) The telson is emarginated at half length, and possesses only one, rather posteriorly situated, dorsal pair of spines. All other species of the P. granulimanus group, and almost all species of Periclimenes , have the lateral margins of the telson regularly converging posteriorly and generally harbour 2 pairs of dorsal telson spines.