Periclimenaeus arthrodactylus Holthuis, This 1952
Creators: name: Bruce, A. J.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Palaemonidae
Periclimenaeus
Periclimenaeus arthrodactylus

description: Periclimenaeus arthrodactylus Holthuis, 1952
(Fig. 1)
Periclimenaeus arthrodactylus Holthuis, 1952: 122–125, figs. 51–53. — Bruce, 2006: 14–15, fig. 7G–I.
Material examined. 1 ♂, CL 1.4 mm, Heron Island reef, north-eastern side, stn HI09-76A, 23°29.990’S, 151°55.601’E, 12 m, 22 November 2009, from dead Acropora and rubble, coll. N. Bruce & K. Schnabel (QM W31895).
Diagnosis. A small Periclimenaeus species with rostral dentition 5/0; with small supraorbital tubercle; ambulatory dactyls biunguiculate, greater than half propod length, unguis ventrally finely denticulate, corpus with 1–4 proximal ventral teeth; propods and third pereiopod merus ventrally spinulate.
Description. Male. Rostrum (Fig. 1B) slender, slightly up-turned distally, dorsally dentate, with 4 well developed acute teeth, 1 small distal denticle, each with single short seta distally, about 0.6 of CL, reaching to middle of intermediate antennular peduncular segment, slightly exceeding anteroverted eyes.
Carapace (Fig. 1A) with small subacute supraorbital tubercle, antennal spine small, acute, marginal; cornea oblique, about 0.32 of CL.
Major second pereiopod missing.
Minor second pereiopod (Fig. 1C) with chela (Fig. 1D) about 1.5 times CL. Palm 1.8 times longer than central depth, oval in section, compressed, about half as thick as central depth, ventral margin with minute acute tubercles, each with a slender seta distally. Fingers (Fig. 1E) 0.57 of palm length; dactyl 3.5 times longer than maximal depth, dorsal margin convex, setose, cutting edge mainly straight with deep marginal lamella, tip acute, feebly hooked; fixed finger 1.7 times longer than proximal depth, cutting edge deeply grooved, medial margin with small acute anteroverted tooth proximally. Carpus about half palm length, distally expanded, unarmed. Merus about 0.6 of palm length, 2.2 times longer than central width, with 4 small acute ventral marginal tubercles. Ischium 0.5 of palm length, 2.5 times longer than distal width, tapering proximally, with smaller ventral tubercles.
Ambulatory pereiopods slender. Third pereiopod (Fig. 1F) with dactyl (Fig. 1I) elongate, slender, biunguiculate, 0.5 of propod length, unguis (Fig. 1J) about 4.5 times longer than basal width, curved, with 13 small acute ventral denticles along its length, 0.25 of corpus length, corpus 4.8 times longer than basal width, curved, tapering distally, with 4 small acute anteroverted teeth on proximal half of ventral margin. Propod (Fig. 1G) about 0.58 of CL, 7.0 times longer than proximal depth, tapering slightly, with pair of short distoventral spines, 6 equally spaced ventral spines, with pair of proximal ventral spines. Carpus 0.75 of propod length, unarmed; merus (Fig. 1H) 1.2 times propod length, 4.6 times longer than central width, with 6 small acute anteroverted ventral tubercles. Ischium 0.75 of propod length, with 3 very small acute tubercles.
Fourth pereiopod similar to third, dactyl slightly longer, unguis with 7 ventral denticles, corpus with 2 proximal ventral teeth (Fig. 1K). Propod with single small distoventral spinule, 2 short, more robust spines on proximal fifth. Merus with 5 minute tubercles, ischium with 2 only.
Fifth pereiopod similar, with dactyl (Fig. 1L) 0.62 of propod length, 1.3 times third pereiopod dactyl length, unguis (Fig. 1M) 0.14 of corpus length with 7 ventral denticles. Propod with small preterminal ventral spine only. Merus and ischium unarmed.
First pleopod endopod (Fig. 1N) 3.0 times longer than proximal width, tapering distally, medial margin straight, with 2 short spiniform setae, lateral margin feebly convex, converging to rounded distal border with 3 short plumose setae, without accessory lobe.
Second pleopod endopod (Fig. 1O) 0.8 of exopod length, with appendices at about 0.5 of medial margin length, corpus of appendix masculina obsolete, with single long slender simple spiniform seta extending beyond end of ramus; appendix interna normal, with sparse distal cincinnuli.
Distribution. Known only from the Pulau Sailus Ketjil, Java Sea, Indonesia, and from Heron Island, Australia.
Remarks. The single specimen is in good condition although lacking the major second pereiopod and with most of the ambulatory pereiopods detached. It agrees well with the original description and the additional data on the holotype provided by Bruce (2006). All ambulatory dactyls are preserved, mainly detached. The ambulatory dactyls are remarkable and diagnostic of the species.
Periclimenaeus arthrodactylus was collected by the Siboga Expedition in 1899 and described by Prof. L. B. Holthuis in 1952, since when there have been no further reports of this species. The discovery of a second specimen on Heron Island, after over a century, indicates a considerable extension of its known range. It was collected from amongst coral rubble and is most probably from a sponge host damaged in the collection process. The holotype was collected from between 0 m and 18 m, similar in depth to the present specimen at 12 m.
description: Published as part of Bruce, A. J., 2010, Pontoniine Shrimps (Crustacea: Decapoda: Palaemonidae) from the CReefs 2009 Heron Island Expedition, with a review of the Heron Island pontoniine fauna, pp. 50-68 in Zootaxa 2541 (1) on pages 51-53, DOI: 10.11646/zootaxa.2541.1.3, http://zenodo.org/record/10094241