Latatheres tomentipes ( Takeda & Konishi, 1994 ) Ahyong, 2018

Ahyong, Shane T., 2018, Revision of Ostracotheres H. Milne Edwards, 1853 (Crustacea: Brachyura: Pinnotheridae), Raffles Bulletin of Zoology 66, pp. 538-571 : 565-566

Latatheres tomentipes ( Takeda & Konishi, 1994) new combination

( Figs. 13 , 14 )

Ostracotheres sp. — Takeda & Konishi, 1989: 1222; 1992: 1305. — Konishi, 1996: 15.

Ostracotheres tomentipes Takeda & Konishi, 1994: 20–23 , fig. 1, 2. — Ng et al., 2008: 250.

Type material. Holotype: NSMT Cr11350, ovigerous female (cl 3.8 mm, cw 4.7 mm), Sesoko-jima Islet, Okinawa, Ryukyu Islands , Japan, coll. S. Kubota, 17 September 1986.

Description. Female: Carapace subrectangular ( Fig. 14A, B ), wider than long, anterior and lateral surfaces finely and sparsely setose, otherwise glabrous, smooth; strongly vaulted longitudinally, rounded in lateral view; front transverse, straight, weakly produced, frontal width about 1/3 carapace width; anterolateral margins undefined, rounded; dorsal surface smooth, regions not indicated.

Epistome ( Fig. 14C ) with broadly triangular interantennular septum; median buccal margin with obtuse median point. Antennular sinus larger than orbit; antennules folded slightly obliquely. Antenna short, free antennal articles extending to about mid-height of eye; antennal articles 1 and 2 fused to epistome. Eye filling orbit, cornea pigmented.

Maxilliped 3 ( Fig. 14D ) ischiomerus length about 2.5 × width; surface and margins sparsely, setose; inner margin weakly concave, distomesial margin rounded, produced slightly beyond palp articulation; outer margin strongly convex. Carpus almost as long as propodus. Propodus spatulate, gently tapering, apex bluntly rounded. Exopod margins sinuous, widest proximally.

Cheliped (pereopod 1) densely covered in short setae ( Fig. 14A, E ). Dactylus relatively straight, pollex curved, apices crossing distally, without gape. Dactylus shorter than dorsal margin of propodus palm, occlusal margin with triangular tooth proximally. Pollex occlusal margin weakly crenulate, with small, triangular tooth near midlength; inner ventral margin with row of setae.. Propodus palm dorsal margin length 1.2 × height; ventral margin distinctly evenly convex. Carpus and merus unarmed; merus stout, longer than propodal palm but shorter than total propodus length.

Walking legs (pereopods 2–5) similar, slender ( Fig. 14A, F–I ); relative lengths: pereopod 2> pereopod 3> pereopod 4> pereopod 5; densely covered in short setae; pereopod 5 articulating slightly dorsad to pereopod 4. Meri unarmed, length 4.2–4.4 × height (pereopods 2–4), 3.2 × height (pereopod 5). Propodi with row of short disto-flexor spinules, length 3.2–4.1 × height (pereopods 2–4), 2.4 × height (pereopod 5). Dactyli simple, surface finely setose, flexor margins of pereopods 2–3 fully setose, of pereopods 4–5 sparsely selose; pereopod 2–3 dactyli equal, weakly curved, longer than pereopod 4–5 dactyli; pereopod 2 and pereopod 4 dactylus 0.6 × propodus length; pereopod 3 and pereopod 5 dactylus 0.8 propodus length.

Egg diameter 0.2–0.3 mm (in preservative).

Hosts. Unidentified bivalve mollusc ( Takeda & Konishi, 1994).

Remarks. Latatheres tomentipes ( Takeda & Konishi, 1994) new combination is known only from the type material collected from unidentified bivalve molluscs. It is readily distinguished from L. affinis by the proportionally shorter, stouter walking legs (pereopod 2 merus length <4.5 × height versus length>5 × height), the position of pereopod 5 (articulating with body above level of pereopod 4, versus on same plane) and the morphology of the walking leg dactyli. In L. tomentipes , the pereopod 2–4 dactyli are weakly curved and the pereopod 5 dactylus falcate, whereas in L. affinis , the pereopod 2 dactylus is strongly falcate and the pereopod 3–5 dactyli, weakly curved. Both species of Latatheres are otherwise very similar, particularly in the maxilliped 3, in which the ischiomerus is comparatively slender, with an evenly rounded distomesial angle that is produced distally beyond the level of the palp articulation. Latatheres tomentipes is probably also more setose than L. affinis , although confirmation must await collection of new material of the latter species.

Distribution. Presently known only from Sesoko-jima Islet, Okinawa, Japan; bathymetric range not known.

Figures

Fig. 13. Distribution of species of Latatheres new genus. (●) L. affinis (H. Milne Edwards, 1853) new combination; (■) L. tomentipes (Takeda & Konishi, 1994) new combination.

Fig. 14. Latatheres tomentipes (Takeda & Konishi, 1994) new combination, ovigerous female holotype, cl 3.8 mm, cw 4.7 mm, Okinawa, NSMT Cr11350. A, dorsal habitus; B, carapace, right lateral view; C, cephalothorax, anterior view; D, right maxilliped 3; E, right chela, anterior view (tomentum omitted); F–I, right pereopods 2–5. Scale: A, B, F–I = 1.0 mm; C, E = 0.5 mm; D = 0.25 mm.