Tubuca dussumieri

Tubuca dussumieri (H. Milne Edwards, 1852)

(Figure 12a–j)

Material examined. 9 ♂, 13 ♀, Kaledupa, Indonesia, 5º 29’ 50’’S, 123º 45’ 20’’E, mud flat in front of mangroves, under houses, L. Michie, 26.08.2014. 11 ♂, 7 ♂, Kaledupa, Indonesia, 5º 29’ 50’’S, 123º 45’ 21’’E, mud flat in front of mangroves, coll. L. Michie, 28.08.2014.

Diagnosis. Carapace: broader than long, smooth; front narrow and practically straight; anterolateral angles acute, not produced; anterolateral margins short; dorsolateral margins distinct and converging. Major cheliped: elongated dactyl and pollex; pollex with medial tooth; gape between dactyl and pollex is triangular in shape due to distinct angle of dactyl; breadth of dactyl consistent along its entire length and only tapers at tip.

Colouration (Figure 12a–d). Adult male. Carapace: black, sometimes with two or three central white markings, anterior ventral surface of carapace and third maxillipeds normally black. Major cheliped: dactyl generally white extending dorsally onto manus, pollex with a white tip and remainder orange which extends ventrally onto manus, usually becoming darker, carpus is a mixture of white, orange and brown, remainder of cheliped usually orange. Minor cheliped & ambulatory legs: generally black, sometimes with last pair blue/white.

Adult female. Carapace: similar to male. Ambulatory legs: similar to males, except sometimes all legs are blue/white.

Juvenile male. Carapace: most often black with two or three central white markings. Major cheliped: dactyl and pollex normally white, remainder is orange.

Juvenile female. Similar to adult females. Ambulatory legs: blue/white.

Gonopod morphology (Figure 12e–h). G1 curved in dorso-lateral direction; large anterior flange, with dark spine at tip of anterior edge; distal protuberance short; pore of sperm channel in midline.

Gastric mill (Figure 12i, j). Urocardiac ossicles simple, with 5 transverse ridges of median teeth, 1–4 decreasing in size distally, fifth one larger and attached to plate dorsally; stem region has 1 pair of cusps. Lateral tooth plate with 18 comb-shaped teeth.

Biology. Tubuca dussumieri is a medium-size species (largest male CL = 14.6 mm, CB = 29.4 mm, largest female CL = 15.9 mm, CB = 24.9 mm); one of the least abundant species on shore, present in mid and high intertidal zones, predominantly associated with shade under buildings or mangrove trees.

Distribution. China, Taiwan, Thailand, Indonesia, Northern Australia, Papua New Guinea.

Remarks. Tubuca dussumieri is the largest species at Ambeua which, along with the large anterior flange of the G1, distinguishes it from the other Tubuca species. The specimens examined agree with the original description. This is however, the first description of the gastric mill for T. dussumieri and the simple morphology which distinguishes it from other Ambeua genera and is similar to the other Tubuca species.