Petalomera Stimpson, 1858

McLay, Colin L. & Ng, Peter K. L., 2007, Revision Of The Indo-West Pacific Sponge Crabs Of The Genus Petalomera Stimpson, 1858 (Decapoda: Brachyura: Dromiidae), Raffles Bulletin of Zoology 55 (1), pp. 107-120 : 108-109

Petalomera Stimpson, 1858

Petalomera Stimpson, 1858: 226 ; 1907: 179; Alcock, 1900: 147; 1901: 55; Borradaile, 1903a: 300 (in part); Ihle, 1913: 48; Sakai, 1936: 28 (in part); Sakai, 1965: 9; Sakai, 1976: 20 (in part); Barnard, 1950: 312; McLay, 1991: 474; McLay, 1993: 164; Dai & Yang, 1991: 25 (in part).

Cryptodromia – Ortmann, 1894: 34 (in part); Ihle, 1913: 32 (in part).

Diagnosis. – Carapace width about equal to or less than length, surface slightly to strongly convex, granulated, may be areolate. Lateral rostral teeth prominent, anterolateral teeth small, obscured by granules or absent. Antennal articles granulated. Coxae of third maxillipeds closely approximated, separated from tip of sternum by deep trough. Female sutures 7/8 end apart between or behind base of first walking legs. Cheliped with epipod. Chelipeds and first 2 pairs of walking legs usually with petaloid meri, carpi and propodi may be crested. Legs not knobbed, inner margins of dactyli of first 2 pairs of legs armed with up to 7 small spines. Last 2 pairs of legs reduced, third pair shortest, dactyli opposed by single propodal spines with sometimes another spine on outer propodal margin. Abdomen of 6 free segments. Uropod plates well developed, visible externally, used in abdominal locking mechanism by fitting in front of large tuberculate knob on bases of first legs. Telson wider than long, tip bluntly rounded. Vestigial pleopods absent on male abdomen abdominal segments 3–5. (Modified from McLay, 1993)

Type Species. – Petalomera granulata Stimpson, 1858 , by original designation and monotypy.

Other Species. – Petalomera indica Alcock, 1900 , Petalomera longipes Ihle, 1913 , and Petalomera pulchra Miers, 1884 .

Remarks. – Twenty species have been assigned to the genus Petalomera over the years (Table 1). Of these, 15 species were originally described in this genus while the other five species were transferred in from two other genera: P. depressa , P. japonica , P. lamellata , P. wilsoni (from Cryptodromia ), and P. lateralis (from Dromia ). After the revision by McLay (1993), only two species, P. granulata Stimpson, 1858 , and P. pulchra Miers, 1884 , remained in the genus; both of which have petaloid meri on their first three pereopods. Petalomera longipes Ihle, 1913 , was placed in synonymy with P. pulchra . However, we here show that P. longipes is in fact a valid species. Thus, we now recognise four species of Petalomera . The other 16 species (number in parenthesis) previously placed in Petalomera are now included in 10 other genera (number of species in parenthesis): Cryptodromia (1 species), “ Dromia ”, (1), Epigodromia (2), Frodromia (2), Fultodromia (1), Hemisphaerodromia (1), Paradromia (2), Stimdromia (5), and Tunedromia (1). Petalomera wilsoni (Fulton & Grant, 1902) was tentatively assigned to Dromia Weber, 1795 , by McLay (1993), but this should be regarded as temporary, pending a review of the genus (D. Guinot, pers. comm.) (see also McLay et al., 2001).

Many dromiid crabs typically carry pieces of sponge or ascidians as camouflage, using their last two pairs of pereopods, but only one instance of carrying behaviour has been reported in the genus, in Petalomera longipes by McLay (1993: 167) (as P. pulchra ).

Species of the genus Petalomera are confined to the vicinity of India, Australia, New Caledonia, Indonesia, Philippines, Taiwan, China and Japan.