Ancylomenes batei, Bruce, 2011

Bruce, A. J., 2011, A new species of Ancylomenes Okuno & Bruce, 2009 (Crustacea: Decapoda: Pontoniinae) from the Kimberley region, Western Australia, Zootaxa 3018, pp. 66-68 : 66-67

Ancylomenes batei sp. nov.

( Fig. 1)

Material examined. Ovig. female, holotype ( WAM C46160), male allotype ( WAM C46161), 1 ♂, 2 ov. ♀ paratypes ( WAM 46576), Western Australia, Long Reef , 13°54.108`S 125°47.465`E, stn. 49/K10-Adhoc, 22 October 2010, coll. A. Hosie, L. Betterridge, scuba, 5 m; 1 male, 1 ovig. female, paratypes ( QM W29053), same collection data; 1 ovig. female, paratype ( OUMNH. ZC. 2011.02.0066), same collection data; 1 ovig. female, paratype ( RMNH D 24753), same collection data. Diagnosis. Rostrum arched, dental formula 8–9/1; carapace with 1 postorbital tooth; third abdominal somite sharply produced posteriorly, not carinate; distolateral margin of proximal segment of antennular peduncle rounded; ophthalmic somite with straight, slender, tapering interocular process; fingers of second pereiopod about 0.75 of palm length, with conspicuous diastema proximally flanked by well-developed anterior and posterior teeth, cutting edges distally entire; carpus of second pereiopod shorter than palm; dactyli of ambulatory pereiopods biunguiculate; propods of ambulatory pereiopods with several long ventral spines, 2–2–1–1–1 .

Measurements (in mm). Holotype female, CL, 3.4; carapace and rostrum, 6.5; total body length, 19.5; major second pereiopod chela, 7.1, minor second pereiopod chela, 2.0; length of ova, ~0.5. Allotype male, CL, 2.8; carapace and rostrum, 4.8; total body length, 17.5; major second pereiopod chela, 3.6, minor second pereiopod chela, 2.4.

Systematic position. Most closely resembling Ancylomenes holthuisi ( Bruce 1969) (see Bruce 1969, 1982), from which A. batei sp. nov. may be readily distinguished by the morphological details of the fingers of the second pereiopod chelae. Okuno (2004) re-examined the holotype female of this species (NHM 1982 45b) and noted that “the cutting edges in P. holthuisi show distinct proximal concavities, thus, the closed fingers appear to gape proximally”. So far, A. holthuisi is the only species of this genus reported to have these proximal concavities. Okuno’s figures show that the concavities are provided with a single small acute tooth anteriorly, obsolescent on the dactylus, without any tooth posteriorly ( Okuno 2004, fig. 6CD). In A. batei sp. nov., a similar proximal concavity is present and the dentition is more strongly developed. The anterior teeth are larger and blunt, that on the fixed finger slightly recurved. On each finger, the posterior margin of the concavity is marked by a well-developed, small, blunt tooth. In A. holthuisi , the minute dactylar teeth oppose each other almost exactly, but in A. batei sp. nov., the fixed finger tooth is more distally positioned than the dactylar tooth ( Bruce 1982, fig. 7; Okuno 2004, fig. 6CD). The ambulatory dactyls in A. batei sp. nov. and A. holthuisi are similar but the propodal spines are longer in A. batei sp. nov., where they distinctly exceed the width of the distal propod, contrasting with A. holthuisi , in which they are only about 0.8 of the distal propod width.

Host. No data.

Colouration. No data.

Etymology. Named in honour of Charles Spence Bate (1819–1889, a British dentist who, in addition to describing the Caridea of the Challenger Expedition (1872–76), also described, as Anchistia aesopia , the first species of the genus Ancylomenes from Gulf Saint Vincent, South Australia ( Bate 1863).

Remarks. The addition of A. batei sp. nov. increases to 18 the number of Ancylomenes species known from the Indo-West Pacific region. Of these 12 are now known from Australian waters: A. adularans (Bruce, 2003) , A. aesopius ( Bate, 1863) , A. holthuisi ( Bruce, 1969) , A. grandidens (Bruce, 2005) , A. kuboi Bruce 2010 , A. magnificus (Bruce, 1979) , A. okunoi Bruce, 2010 , A. speciosus ( Okuno, 2004) , A. tenuirostris (Bruce, 1991) , A. tosaensis (Kubo, 1951) , A. venustus (Bruce, 1990) , and A. batei sp. nov.