Periclimenes sp.

Li, Xinzheng & Bruce, Alexander J., 2006, Further Indo-West Pacific palaemonoid shrimps (Crustacea: Decapoda: Palaemonoidea), principally from the New Caledonian region, Journal of Natural History 40 (11 - 12), pp. 611-738 : 723-725

Periclimenes sp.

( Figure 31 )

Material examined

La Réunion: MD 32 , stn DS173, 20 ° 51.59S, 55 ° 36.89E, 270 m, 8 September 1982, 1♀ (MNHN-Na 14927) .

Description

The single specimen, cl 2.7 mm, unfortunately lacks both second pereiopods and the posterior part of the telson; right first pereiopod, third and fifth pereiopods detached. It is a small pontoniine shrimp with subcylindrical body form.

Carapace smooth, glabrous. The rostrum is long and slender, horizontal mostly and feebly upcurved distally, well exceeding the antennular peduncle and subequal to the postorbital carapace length, with a dentition of 1+6/5, epigastric spine and dorsal rostral teeth are large, long, slender and acute, as are ventral teeth, except for minute distal tooth, epigastric spine with basal suture, situated at anterior 0.4 of carapace length, first dorsal tooth on carapace, second dorsal tooth at level of posterior orbital margin. Supraorbital spine absent; antennal spine long, slender, marginal, close to inferior orbital angle, distinctly exceeding inferior orbital angle; hepatic spine large, as long as antennal spine, more robust, at same level as antennal spine, below the level between epigastric spine and first dorsal rostral tooth.

Third abdominal segment with feebly dorsal prominence; sixth segment about 2.1 times length of fifth, subcylindrical, about 1.7 times longer than central depth, posterolateral angle acute, posteroventral angle rounded.

Eye well developed, with globular cornea, corneal diameter 0.18 of posterior orbital carapace length, feebly pigmented, without accessory pigment spot; stalk subcylindrical, slightly wider than cornea in dorsal view.

Antennular peduncle overreaching third ventral rostral tooth; upper flagellum biramous, with proximal four segments fused, shorter free ramus with four segments, with nine groups of aesthetascs. Antennal basicerite robust, with strong acute lateral tooth; scaphocerite exceeding antennular peduncle, reaching basal fourth ventral rostral tooth; lateral margin straight, distolateral tooth almost reaching distal end of lamella.

Epistome with well-developed rounded bosses.

Fourth thoracic sternite without slender median process, with broad shallow transverse plates, separated by deep median fissure, fifth sternite similar, transverse plates subequal to those of fourth; posterior sternites unarmed.

Mandible without palp; incisor process distally with three (right) or four (left) stout acute teeth, central teeth smaller than outer teeth. Third maxilliped reaching to basal carpocerite, coxa with arthrobranch distinct.

First pereiopods moderately slender, reaching distal end of scaphocerite, exceeding carpocerite by chela and half carpus. Ambulatory pereiopods robust, third pereiopod exceeds carpocerite by dactyl and distal two-thirds propod; dactyl compressed, long, slender, simple, unguis distinct; propods with long distoventral spine and three small ventral spinules. Uropod slender; protopodite with distolateral lobe broadly rounded; exopod with lateral border feebly convex, with small distal tooth, and larger mobile spine medially, diaeresis distinct.

Remarks

Although the peculiar rostrum, armature on carapace, epistome with well-developed rounded bosses, and the feebly dorsal prominence on third abdominal segment show that the present taxon is distinguishable from almost all of the members in the genus, it is difficult to present it as a new species as it lacks both second pereiopods and the posterior part of the telson. These deficiencies make its exact systematic position unclear. More material is necessary to decide its precise systematic position. The armature of rostrum and carapace, particularly the long and acute rostral teeth and the hepatic spine which is at same level as antennal spine, looks somewhat like that of P. latipollex Kemp, 1922 . The present form can be easily distinguished from that species by the simple dactyls of ambulatory pereiopods and deeper rostrum (not rod-like, although shallow).

Figures

Figure 31. Periclimenes sp. 1, female (MNHN-Na 14927). (a) Body, lateral view; (b) rostrum; (c) first pereiopod; (d) same, propod and dactyl.