Tubuca demani (Ortmann, 1897)

Michie, Laura A., Barnes, R. S. K., Clark, Paul F., Bennett, Wayne A. & Cragg, Simon M., 2021, Distinguishing ten sympatric species of fiddler crab (Decapoda: Ocypodidae) using a suite of phenotypic characteristics, Zootaxa 5026 (4), pp. 480-506 : 498

Tubuca demani (Ortmann, 1897)

( Figure 11a–j )

Material examined. 8 ♀, 10 ♂, Kaledupa , Indonesia, 5º 29’ 50’’S, 123º 45’ 20’’E, mud flat in front of mangroves, under houses to the west, coll. L. Michie, 26.08.2014 . 12 ♀, 10 ♂, Kaledupa , Indonesia, 5º 29’ 50’’S, 123º 45’ 21’’E mud flat in front of mangroves, coll. L. Michie, 28.08.2014 .

Diagnosis. Carapace: Carapace broader than long, smooth; front narrow anterolateral angles strongly acute, produced; anterolateral margins short to absent, developing gradually into dorsolateral margins which are distinct and converge strongly. Major cheliped: manus an equal length to dactyl and pollex; dactyl often slightly longer than pollex; pollex almost straight, dactyl slightly wider than fixed finger proximally; dactyl and pollex possess a medial tooth.

Colouration ( Figure 11a–d ): Adult male. Carapace: variable, can be entirely grey, sometimes grey with black horizontal band posteriorly, or black ‘W’ shape, eyestalks red to dark brown, anterior ventral surface of carapace and third maxillipeds grey or dark brown. Major cheliped: dactyl and pollex with white tips and proximally orange which extends to manus, proximal end of manus red/brown, carpus usually same colour as adjacent manus, remainder of cheliped orange/russet. Minor cheliped & ambulatory legs: dark brown, grey or black.

Adult female. Carapace: varies, mainly grey with black transverse band ventrally, sometimes being orange and occasionally dark brown. Ambulatory legs: similar to males.

Juvenile male. Carapace: usually grey with black ‘W’ shape, sometimes grey with black transverse band posteriorly. Major cheliped: dactyl and pollex generally white/light brown remainder of cheliped orange, becoming darker with maturation.

Juvenile female. Carapace: grey or dark orange. Chelae: dark brown. Ambulatory legs: orange, brown or grey.

Gonopod morphology ( Figure 11e–h ). G1 curved in dorsolateral direction; distal end short with rounded tip; distal protuberance short, barely reaching base of flanges; flanges moderately short; pore of sperm channel large.

Gastric mill ( Figure 11i, j ). Urocardiac ossicles simple, with 4 transverse ridges of median teeth, all similar shape and size, first one slightly larger, all marginally arched; stem region has 1 pair of cusps, lateral tooth plate with 18 comb-shaped teeth.

Biology. Tubuca demani is a medium-size species (largest male CL = 16.9 mm, CB = 28.9 mm, largest female CL = 13.1 mm, CB = 20.8 mm); one of least abundant species on shore, present in mid and high intertidal zones, predominantly associated with shade under buildings or mangrove trees.

Distribution: Indonesia, Southern Philippines.

Remarks. Tubuca demani can be distinguished from other Tubuca species by the curved tip of the G1 and the colouration. The specimens examined conform with the original description. Presented here is the first description of the gastric mill for T. demani and the simple morphology which distinguishes it from other Ambeua genera and is similar to the other Tubuca species described here.

Figures

FIGURE 11. Tubuca demani (Ortmann, 1897): a–d Sulawesi Tenggara, Indonesia. Adult male colouration; a, large chela; b, carapace dorsal view. Adult female colouration; c, frontal view; d, carapace dorsal view. Photos credit L. Michie. Line drawing of left G1; e, lateral view; f, mesial view; CLSM images of apical part of G1; g, lateral view; h, mesial view; SEM images of male gastric mill; i, median tooth plate, ventral view; j, left lateral tooth plate, mesial view.