Palaemonella dijonesae Bruce 2010, sp. nov.

Palaemonella dijonesae sp. nov.

(Fig. 1)

Palaemonella spinulata. — Bruce, 2008a: 107–108, figs 2–3.

Material examined. Holotype, ov. female WAM C29308, Rocky Head, Enderby Island, Dampier Archipelago, stn DA2/99/73, 20°40’14”S, 116°27’96”E, 12.5 m, 24 July 1999; paratype male, WAM C28094, Nelson Rocks, Dampier Archipelago, stn DA3/99/68, 20°27.998’S, 116°39.707E, 6.3 m, 7 July 1999.

Diagnosis. Rostrum as long (female) or longer (male) than CL, dentition 1+7/2, carapace without postorbital ridge, supraorbital spines present, well developed, antennal spine only slightly exceeding inferior orbital angle, mandibular palp 2-segmented, distal segment twice length of proximal segment, second pereiopods without distoventral ischial spine, ambulatory dactyli not elongate.

Description. The major features of a male of P. dijonesae have been described and illustrated by Bruce (2008a, Figs 2–3 as P. spinulata). These can be augmented by further description of the female holotype specimen.

Rostrum (Fig. 1B) subequal to CL, straight, horizontal, dorsal carina well developed, with 6 acute teeth and minute preterminal tooth (Fig. 1C), first tooth well in advance of posterior orbital margin, teeth with 3–4 plumose interdental setae, ventral carina well developed distally with 2 well developed acute teeth distal to fourth dorsal tooth, ventral margin with submarginal plumose setae distally, longer median setae proximally. Carapace (Fig. 1A) with epigastric tooth at 0.72 of CL, supraorbital spine well developed, without supraorbital or postorbital ridges, inferior orbital angle feebly produced, antennal spine well developed, marginal, extending slightly beyond inferior orbital angle, hepatic spine well developed, at slightly lower level than antennal spine, below supraorbital spine.

Third maxilliped with 7 distolateral meral spinules, terminal segment with strong distal spine.

First pereiopod chela (Fig. 1D) with fingers slightly longer than palm length, slender, dactylus about 6.5 times longer than proximal depth, with small hooked tip, cutting edges straight, laminar, entire; corpus of oval section, about 2.3 times longer than central depth, with 5 transverse rows of short curved serrulate setae proximo-ventrally, with longitudinal row of 3 longer straight simple setae more dorsally (Fig. 1E).

Right second pereiopod only, chela (Fig. 1F) about 1.6 times CL, 3.5 times longer than central depth, fingers (Fig. 1G) about 0.73 of palm length, slender with strongly hooked tips, dactylus 6.2 times longer than proximal depth, proximal third of cutting edge with 2 small acute teeth, distal cutting edge laminar, entire, fixed finger similar, with 2 slightly larger teeth proximally, with further rudimentary rounded tooth more proximally; carpus 0.43 of chela length, distally swollen, with preterminal constriction, distally cupped with medial and lateral bluntly angular projections (Figs. 1H–I); merus 0.52 of palm length, with strong terminal distoventral tooth; ischium 0.39 of palm length, unarmed.

Third ambulatory pereiopod with propodus (Fig. 1J) about 0.7 of CL, about 14 times longer than wide, with distoventral spines missing, 5 small ventral spines, with 2 spiniform setae disto-dorsally, dactylus (Fig. 1K) 6.5 times longer than basal width, 0.27 of propodus length, dorsal margin with 2 simple setae at about half length, ventral margin feebly biconcave, unguis distinctly demarcated; fourth pereiopod similar to third, distoventral propodus with 2 short spines, about 0.2 of dactylus length,.

Measurements. Holotype female, postorbital carapace length, 2.3 mm; carapace and rostrum, 4.5 mm; total body length, 14.0 mm; major second pereiopod chela, 3.7 mm; length of ovum, 0.5 mm. Paratype male, postorbital carapace length, 2.3 mm; carapace and rostrum, 4.5 mm; total body length, 14.0 mm; major second pereiopod chela, 6.3 mm; minor second pereiopod chela, 6.0 mm.

Etymology. Named in honour of Dr Diana S. Jones, Acting Chief Executive Officer, Western Australian Museum, Perth, and principal organizer of the Dampier Archipelago surveys.

Colouration. No data.

Systematic position. Palaemonella dijonesae sp. nov. most closely resembles Palaemonella spinulata Yokoya, 1936, with which it was earlier confused. The most conspicuous difference between P. dijonesae sp. nov. and P.spinulata is the presence of a well developed supraorbital spine and the absence of supra- and postorbital ridges in the former and the small supraorbital spines and well developed post-orbital carina in the latter, which also has small supraorbital ridges. In P. dijonesae sp. nov. the first pereiopod fingers are subequal to the palm length, in P. spinulata distinctly longer. In P. dijonesae sp. nov. the male rostrum is distinctly longer than the carapace length, in P. spinulata, about subequal.

Remarks. Palaemonella spinulata has been reported in Australian waters from the Cobourg Peninsula, Northern Territory (Bruce & Coombes 1995); Darwin Harbour, Fannie Bay, (Bruce & Coombes 1997); Moreton Bay, Dunwich, Queensland (Bruce 1983); Heron Island (Bruce 1981); North East Herald Cay (Davie & Short 2001). These specimens are likely to belong to P. dijonesae and need to be re-examined to establish their identities. The same can also apply to the specimens of P. spinulata reported from New Caledonia and the Loyalty Islands (Touho; Lifou, Santal Bay, and numerous adjacent localities, Li & Bruce 2006). The specimens reported from Chinese waters in Li (2001) from Dadonghai, Sanya and Xiaodonghai, Hainan Island, are most likely to be correctly identified. However, the specimens from the northern Mariana Islands (Agrihan Island, Hayashi et al. 1994) and the Austral Islands (Rapa and Rarapai Islands, Li 2008) should probably also be re-examined. Also the specimen from Souris Chaude, La Réunion (Bruce 1978) should be reassessed, if it can be located, as it may belong to P. maziwi Bruce, 2002a.