Atydina atyoides (Nobili, 1900) comb. nov.

(Figs. 1–2)

Caridina atyoides Nobili, 1900: 478 . [type locality: Sioban, Pulau Sipura, Kepulauan Mentawei, off west coast of Sumatra, Indonesia].

Caridina atyoides . — Bouvier, 1925: 256, fig.587. — Roux, 1928: 205. — Chace, 1997: 7.

Material examined. 1 male, cl 10.7 mm, 1 ov. female, cl 9.3 mm, ZMA Crust DE 202877, River Teobak, Western Ceram, Moluccas, Indonesia, coll. De Beaufort, Feb. 1910.

Description. Rostrum (Fig. 1 A) short, sloping down rather abruptly, reaching near to end of basal segment of antennular peduncle, rostral formula 0/0-2, ventral teeth small, indistinct. Inferior orbital angle acute, fused with antennal spine; pterygostomial margin rectangular.

Sixth abdominal somite 1.3 times as long as high, 0.37 times as long as carapace, 1.3 times as long as fifth somite, as long as telson. Telson (Fig. 1 B) 2.0 times as long as wide, distal margin rounded, terminating in a projection, with 5 pairs of dorsal spinules and 1 pair of dorsolateral spinules; distal end with 3 or 4 pairs of spines, lateral pair shorter than intermediate pairs. Preanal carina (Fig.1 J) high, sub-triangular, without spine.

Eyes well developed, anterior end reaching to 0.7 length of basal segment of antennular peduncle. Antennular peduncle 0.4 times as long as carapace; basal segment of antennular peduncle as long as combined length of second and third segments, anterolateral angle reaching to 0.2 length of the second segment, second segment distinctly longer than third segment. Stylocerite reaching to 0.9 length of basal segment of antennular peduncle. Scaphocerite 2.6 times as long as wide.

Incisor process of mandible (Fig. 1 C) ending in a row of small teeth, molar process truncated. Lower lacinia of maxillula (Fig. 1 D) broadly subrectangular, upper lacinia elongate, with a number of distinct teeth on inner margin, palp slender. Upper endites of maxilla (Fig. 1 E) subdivided, palp short, scaphognathite tapering posteriorly with numerous long, curved setae at posterior end. Palp of first maxilliped (Fig. 1 F) ending in a finger-like projection. Second maxilliped (Fig. 1 G) typical for Atyidae, arthrobranch well developed. Third maxilliped reaching to end of antennular peduncle, with ultimate segment as long as penultimate segment.

Epipods well developed on first 4 pereiopods. First pereiopod (Fig. 1 H) reaching slightly beyond anterior end of basal segment of antennular peduncle; merus 3.4 times as long as broad, distinctly longer than carpus; carpus excavated anteriorly, shorter than chela, 1.6 times as long as high; chela 2.1 times as long as broad; fingers as long as palm. Second pereiopod (Fig. 1 I) reaching to end of scaphocerite; merus as long as carpus, 4.0 times as long as broad; carpus 1.2 times as long as chela, 4.4 times as long as high; chela 2.5 times as long as broad; fingers 1.7 times as long as palm. Third pereiopod (Figs. 2 A–B) reaching beyond end of scaphocerite by 1/3 of its propodus, with a prominent meral spur in large male, propodus 4.0 times as long as broad, 2.6 times as long as dactylus; dactylus 2.0 times as long as wide (spines included), terminating in a big claw, with 6 accessory spines on flexor margin. Fourth pereiopod (Figs. 2 E–F) similar to third one in form, but smaller in size, with no spur. Fifth pereiopod (Figs. 2 G–I) reaching to end of basal segment of antennular peduncle, propodus 8.5 times as long as broad, 3.4 times as long as dactylus; dactylus slender, 3.2 times as long as wide (spinules included), terminating in one claw, with 106 spinules on flexor margin.