Danarma garfunkel (Davie & Ng, 2013)

(Figs. 13D, 14B)

Sesarma (Holometopus) obtusifrons – Balss, 1934: 229.

Sesarma obtusifrons – Gibson-Hill, 1947: 44; Tweedie, 1947: 33; George, 1978: 13 (unnumbered pages); Hicks et al., 1984: 22, 65, with colour photograph.

Chiromantes obtusifrons – Davie, 2002: 221; Ng & Davie, 2012: 18; Orchard, 2012: 198, 199.

Chiromantes garfunkel Davie & Ng, 2013: 7, figs. 2, 4E, 5F, 6F, 7F, 8D, 9F, 10B, 12; Aw & Low, 2020: 8.

Material examined. Holotype male (17.0 × 13.0 mm) (QM, ex ZRC 2009.0822), Greta Beach, Christmas Island, coll. H.H. Tan, 8 December 2007. Paratypes – 4 males (13.5 × 10.2 mm, 15.2 × 11.6 mm, 18.2 × 14.7 mm, 17.9 × 14.0 mm), 4 females (13.0 × 9.6 mm, 14.3 × 10.8 mm, 14.7 × 11.2 mm, 17.5 × 13.6 mm) (ZRC 2012.0778), station CI-06, Grotto, Waterfall Road, 10°25.386′S 105°42.127′E, weathered cave, tidal sump, coll. 23 January 2010; 1 female (12.1 × 9.1 mm) (ZRC 2012.0780), station CI-04, Merrial Beach, 10°28.455′S 105°33.551′E, sandy beach, beach forest, limestone base rock, coll. 20 March 2011; 1 male (13.5 × 10.2 mm) (ZRC 2012.0781), Ethel Beach, 10°27.805′S 105°42.443′E, sandy beach, beach forest, limestone base rock, station CI-09, coll. 21 March 2011; 1 female (13.3 × 12.0 mm) (ZRC 2012.0776), Greta Beach, 10°30.127′S 105°40.475′E, station CI-33, coll. 27 March 2011; 1 female (11.1 × 8.3 mm) (ZRC 2012.0782), Flying Fish Cove, 10°25.815′S 105°40.180′E, rocky, gravel beach, station CI-01, coll. 22 January 2010; 1 ovigerous female (11.4 × 8.6 mm) (ZRC 2012.0783), Flying Fish Cove, 10°25.815′S 105°40.180′E, rocky, gravel beach, station CI-01, coll. 22 January 2010; 1 female (10.8 × 8.2 mm) (ZRC 2012.0785), Lily Beach, 10°28.011′S 105°42.688′E, sandy beach, beach forest, limestone base rock station CI-02, coll. 22 January 2010; 1 male (13.9 × 10.6 mm) (ZRC 2012.0777), Greta Beach, 10°30.127′S 105°40.475′E, limestone cliff, sandy beach, limestone bedrock, station CI-12, coll. 24 January 2010; 1 male (14.0 × 10.8 mm) (ZRC 2012.0784), Flying Fish Cove, 10°25.815′S 105°40.180′E, rocky, gravel beach, 22 January 2010; 2 males (10.8 × 9.8 mm, 14.5 × 13.2 mm) (ZRC 2012.0779), Waterfall Bay, Christmas Island Resort, 10°27.54′S 105°42.30′E, freshwater stream, sandy beach, limestone base rock, station CI-07, coll. 23 January 2010; 1 female (11.6 × 8.6 mm) (ZRC 2012.0786), Lily Beach, 10°28.011′S 105°42.688′E, sandy beach, beach forest, limestone base rock, station CI-02, coll. 22 January 2010; 1 male (13.7 × 10.4 mm) (ZRC 1965.7.29.153), no specific location, coll. 1932; 2 paratype males (larger 11.5 × 8.8 mm), 7 paratype females (largest 20.4 × 16.2 mm) (ZRC 1965.7.29.154–163), shore terrace along east and north coasts, and Isabel Beach, Christmas Island, coll. M.W.F. Tweedie, 2 March 1932. All locations on Christmas Island .

Diagnosis. Carapace transversely subovate, ca. 1.3 times broader than long; dorsal carapace, lateral branchial regions prominently swollen; external orbital tooth at widest point only projecting slightly more than external orbital tooth; front ca. 0.6 times carapace width, margin broadly convex in dorsal view, appearing smooth but microscopically granular, with pair of weak lateral swellings behind margin; supraorbital margin entire, straight, obliquely sloping posteriorly; outer surface of cheliped carpus moderately granular; ambulatory legs relatively short; third ambulatory merus ca. 2.3 times longer than wide; fourth ambulatory merus relatively narrower than third ambulatory merus, ca. 2.6 times longer; third ambulatory propodus ca. 2.8 times longer than wide; fourth ambulatory propodus ca. 2.7 times longer; male pleon (moderately broad; somite 6 with lateral margins diverging, slightly concave over distal half, more subparallel over proximal half; somite 3 width 3.0 times basal width of telson; G1 relatively slender, weakly tapering to prominent subdistal shoulder; distal chitinous process long, with slender narrow apex, dorsal margin slightly sinuous. (After Davie & Ng, 2013: 9).

Colour. “Carapace and legs of adults rich, dark purple to maroon; without prominent speckling or splotching. Legs uniform in colour, without transverse banding. Chelipeds relatively uniform in colour, not clearly darker dorsally; off-white to white porcelain in adults, markedly contrasting with purple carapace. Ocular peduncles same as carapace in colour; corneas bright yellow. Female specimens from more exposed supralittoral areas behind beaches can be paler in coloration, with the carapace and legs beige with streaks of purple and brown. Their eyes, however, are still bright yellow.” (Davie & Ng, 2013: 12, 13, fig. 2).

Remarks. The taxonomy of this species has been treated at length by Davie & Ng (2013).

Biology. This species is typically found in the supralittoral, usually among limestone or similar formations. Crabs have been observed to climb many metres up on karst cliffs. They are primarily nocturnal, apparently feeding on the algae growing on the rocks. Gibson-Hill (1947: 44) states that the preferred spawning period is between January to April, with broods estimated at 5,500 eggs. See also Davie & Ng (2013: 14).

Distribution. Known only from Christmas Island (Davie & Ng, 2013).