Periclimenes chacei, Li & Bruce & Manning*, 2004

Li, Xinzheng, Bruce, Alexander J. & Manning *, Raymond B., 2004, Some Palaemonid Shrimps (Crustacea: Decapoda) From Northern South China Sea, With Descripitions Of Two New Species, Raffles Bulletin of Zoology 52 (2), pp. 513-553 : 542-544

Periclimenes chacei , new species

( Figs. 27 , 28 )

Material examined. – Holotype - 1 ovig female, CN 92 C-182D3, Xincun , Hainan Is., 1-3m, with living corals, coll. X. Li and V. Neumann, 27 Mar.1992.

Diagnosis. – Small sized pontoniine shrimp. Rostrum short, deep, dorsal margin convex, with 0 + 6/0 teeth. Carapace without supraorbital spine. Scaphocerite broad, distal margin of lamella distinctly produced, much over-reaching distolateral tooth. Fourth thoracic sternite without median process. Second pereiopods without distoventral tooth on merus; carpus 0.6 times as long as palm, unarmed distally; chela with fingers 0.33 as long as palm. Ambulatory pereiopods with dactyl simple; propodus with spines on flexor margin; fifth pereiopods not reaching as far as end of scaphocerite.

Description. – Small sized shrimp. Integument smooth.

Rostrum deep and compressed laterally, over-reaching second segment of antennular peduncle, broadened laterally in proximal part; dorsal margin distinctly convex, with 6 teeth and few setae between teeth, the teeth vary gradually smaller towards the apex, posteriormost tooth at level of orbital margin; tip rounded; ventral margin very slightly convex, with few setae on the proximal part, without tooth. Carapace without supraorbital spine, lower orbital angle slightly produced anteriorly; antennal spine marginal, placed some distance below orbit; hepatic spine larger than antennal spine, placed distinctly lower to latter.

Thoracic sternites without process, fourth and fifth with distinct transverse ridges, the ridge on sixth thoracic sternite indistinct.

Abdomen smooth; pleura of anterior five somites broadly rounded, sixth somite 1.9 times longer than fifth, with both of posterolateral and posteroventral angles rounded.

Telson elongate, subequal to sixth abdominal somite in length, 3.5 times as long as proximal width, lateral margins somewhat straight; dorsal surface with 2 pairs of spines on posterior half, posterior pair slightly nearer to anterior than to posterior margin of telson; posterior margin bearing 3 pairs of spines, lateral pair extremely short, like dorsal spines, intermediate pair long and robust, submedian pair slender, about 0.6 as long as intermediate pair.

Eyes well developed, cornea globular, shorter than stalk, ocellus distinct.

Antennule with first segment broad, outer margin slightly convex, anterolateral spine over-reaching adjacent convex anterior margin of segment, without a small tooth at half length ventromedially; stylocerite not reaching middle of segment; second segment shorter and broader than third, length of second and third segments about half as long as first; both rami of upper antennular flagellum fused proximally for 8 segments, free part of shorter ramus consisting of 5 segments and shorter than half of fused portion. Antenna with basicerite laterally armed with a triangular tooth; scaphocerite distinctly over-reaching antennular peduncle; outer margin straight, distolateral tooth not reaching end of lamella; lamella broad, 3 times as long as wide, with anterior margin strongly produced.

Mandible slender, incisor process with 5 small acute teeth. Second maxilliped without podobranch. Third maxilliped with last segment 0.8 as long as penultimate segment, exopod just reaching to, but not beyond the end of antepenultimate segment; ischiomerus and basis distinct.

First pereiopod slender, fingers shorter than palm, cutting edges entire; carpus about 1.25 times as long as chela; merus slightly shorter than carpus; ischium more than half of merus. Second pereiopods slender and equal; fingers short, about 0.33 as long as palm, movable finger with 2 strong tooth in the proximal half on cutting edge, fixed finger bearing 1 tooth opposed to distal tooth of movable finger; carpus 0.6 as long as palm, with distal margin unarmed; merus shorter than palm but longer than carpus, without distal tooth on flexor margin; ischium subequal to merus in length. Third pereiopods slender; dactyl 0.33 as long as propodus, simple, with apical 0.4 curved and narrow; propodus with few spines on flexor margin. Fifth pereiopods not reaching end of scaphocerite.

Uropods over-reaching tips of posterior marginal telson spines, exopod bearing lateral movable spine, lateral fixed tooth indistinct.

Eggs relatively large, diameter 0.29-043 mm.

Measurements (in mm). – Holotype: CL, 2.3; carapace and rostrum, 4.0; second pereiopod: dactyl, 0.57: chela, 2.49: carpus, 1.30: merus, 1.68; ischium, 1.55.

Coloration. – No data.

Etymology. – The specific name is given in honor of the late Dr. Fenner A. Chace, Jr. (1908-2004), famous carcinologist of the National Museum of Natural History, Smithsonian Institution, Washington.

Remarks. – This very small Periclimenes species is closely allied to Periclimenes ruber Bruce, 1982b , which was collected from Queensland in association with crinoid host, and also with long and slender second pereiopods. The new species can be distinguished from P. ruber by its deeper rostrum, hepatic spine on carapace distinctly posteroventral to the antennal spine, equal second pereiopods (the major second pereiopod of P. ruber looks very large), and cutting edges second pereiopods fingers with 2 teeth on dactyl and 1 on fixed finger.

Figures

Fig. 27. Periclimenes chacei, new species. a, carapace and anterior appendages, lateral view; b, anterior region and rostrum; c, eye; d, antennule; e, antenna; f, mandible; g, 3rd maxilliped; h, eggs.

Fig. 28. Periclimenes chacei, new species. a, 1st pereiopod; b, same, fingers; c, 2nd pereiopod; d, same, fingers; e, 3rd pereiopod; f, same, dactyl; g, telson and uropod, dorsal view.