Danarma obtusifrons
Creators: name: Schubart, Christoph D.
name: Ng, Peter K. L.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Sesarmidae
Danarma
Danarma obtusifrons

description: Danarma obtusifrons (Dana, 1851)
(Figs. 13A, 14A, 18A, 19A–C, F–I, 43E)
Sesarma obtusifrons Dana, 1851: 250; Dana, 1852: 355, pl. 22, fig. 9; H. Milne Edwards, 1853: 183; De Man, 1887: 644; Lenz, 1901: 472; Titcomb et al., 1979: 367; Godwin & Bolick, 2006: 39, 49.
Sesarma (Holometopus) obtusifrons – Rathbun, 1906: 840; 1907: 35; Tesch, 1917: 179 (part); Edmondson, 1946: 306, fig. 183e; Edmondson, 1959: 185, figs. 13c, 17c; Serène, 1968: 107 (part).
Chiromantes obtusifrons – Ng & Liu, 1999: 230.
“ Chiromantes ” obtusifrons – Ng et al., 2008a: 220, 224 (part); Castro, 2011: 120; Davie & Ng, 2013: 2, figs. 1, 4A, 5A, B, 6A, B, 7A, B, 8A, 9A, B, 10A, 11.
Incertae sedis [see remarks later] (see Davie & Ng, 2013: 7)
Sesarma (Sesarma) obtusifrons – De Man, 1895: 161; De Man, 1898: pl. 29, fig. 31.
Material examined. 2 males (16.8 × 12.9 mm, 19.7 × 14.7 mm) (ZRC 2002.0220, ex. BPBM-266), Malaikahana, Oahu, Hawaii, C.M. Cooke et al., 8 July 1916; 1 male (17.7 × 13.2 mm), 1 female (15.7 × 11.6 mm) (UF-FLMNH 14837), 21.2833°N 157.667°E, Coco Head, Oahu, Hawaii, coll. G. Paulay et al., October 2006.
Diagnosis. Carapace transversely rectangular, ca. 1.3 times broader than long; dorsal carapace, lateral branchial regions weakly convex, not prominently swollen; external orbital tooth with outer margin broadly convex so greatest carapace width clearly posterior to external orbital tooth; front ca. 0.65 times carapace width, margin broadly convex in frontal view with medial part relatively straight in dorsal view, beaded with row of small but distinct granules, with pair of low lateral swellings behind margin; supraorbital margin entire, semicircular; dorsal surface of cheliped carpus covered in small but conspicuous granules; ambulatory legs relatively short; third ambulatory merus ca. 2.2 times longer than wide; fifth ambulatory merus ca. 2.3 times longer; fourth ambulatory propodus ca. 2.2 times longer; male pleon moderately broad; somite 6 with distolateral margins strongly divergent, relatively straight over distal two-thirds; somite 3 width 2.9 times basal width of telson; G1 relatively slender, weakly tapering to obtusely angled subdistal shoulder; distally slender, strongly bent to 45° angle; distal chitinous process long, with slender narrow apex, dorsal margin slightly concave. (After Davie & Ng, 2013: 2).
Colour. “Background colour of carapace, legs fawn to bluish gray, covered in fine darker speckling with scattering of slightly larger irregular spots. Legs with darker, broad transverse bands that are more noticeable on the carpi and meri. Chelipeds dorsally similar in colour to carapace and legs but becoming greyish white in frontal and ventral view. Ocular peduncles and corneas pale, similar to carapace in colour.” (Davie & Ng, 2013: 5; fig. 1).
Remarks. This characteristic species has been reported from a wide area from the eastern Indian Ocean to Hawaii (type locality). Davie & Ng (2013) revised the taxonomy of the species and recognised four new species. All these species share the diagnostic generic features of the genus. Although the type(s) of Sesarma obtusifrons Dana, 1851, are almost certainly lost, Davie & Ng (2013) argued that there was no need to designate a neotype as the species is distinctive and easily distinguished for all known congeners.
Biology. “ Edmondson (1959) noted that C. obtusifrons was found intertidally and “even above the high water mark”, and Paulay & Starmer (2011: 11) reported finding it living in a supratidal boulder field on O‘ahu.” (Davie & Ng, 2013: 7).
Distribution. Known only from Hawaii (Davie & Ng, 2013).
description: Published as part of Schubart, Christoph D. & Ng, Peter K. L., 2020, Revision of the intertidal and semiterrestrial crab genera Chiromantes Gistel, 1848, and Pseudosesarma Serène & Soh, 1970 (Crustacea: Brachyura: Sesarmidae), using morphology and molecular phylogenetics, with the establishment of nine new genera and two new species, pp. 891-994 in Raffles Bulletin of Zoology 68 on page 922, DOI: 10.26107/RBZ-2020-0097, http://zenodo.org/record/5351295