Petalomera indica Alcock, 1900

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 : 112-113

Petalomera indica Alcock, 1900

( Fig. 4 )

Petalomera granulata var. indica Alcock, 1900: 148 .

Petalomera indica – Alcock, 1901: 55, Pl. 3, Figs. 14, 14a; Ihle, 1913: 48, 91 (key & list).

Not Petalomera granulata var. indica Urita, 1926: 1 [= Petalomera granulata Stimpson, 1858 ].

Material examined. – None.

Type specimens. – Alcock indicated that the “types” of P. indica in the Indian Museum came from Port Blair , Andamans, were collected by Wood-Mason and were recorded under the reference number 713. He did not indicate how many “types” there were or their sex and dimensions. When these syntypes are located a lectotype specimen should be selected .

Description. – Carapace sparsely setose, legs densely setose. Carapace slightly longer than wide, convex in both directions, with numerous unevenly distributed vesiculous granules. All regions distinct, but not equally well defined. Cervical, branchial and branchio-cardiac grooves well marked.

Rostrum dorsally grooved in mid-line, cut into 3 serrulate teeth, lateral rostral teeth large, triangular, median tooth small and on a lower level. Upper border of orbit serrulate, with a tooth sub-medially. Outer orbital angle pronounced but not dentiform. A straight line connects tip of lateral rostral tooth and postorbital corner, running along anterior carapace margin. Suborbital margin with a granular denticle.

Anterolateral carapace border cut into 3 blunt granular teeth, the first being subhepatic. Number of teeth variable (see below).

Chelipeds more massive than walking legs, these and first pair of walking legs with petaloid meri. Merus of second walking legs not petaloid, although upper border sharp. Inner border of carpus and upper border of propodus prominent, granular, like upper and outer surfaces of these joints; 2 sharp tubercles present on distal end of outer surface of carpus. First 3 pairs of walking legs with few small granules on some joints.

Last 2 pairs of legs slender, ending in small claw-like dactylus opposable to strong propodal spines. Ratio of length along dorsal margin (not including spine) to width of propodus for third and fourth legs, 1.9 and 1.3, respectively. Last pair of legs slightly longer than penultimate pair.

Abdomen in both sexes with central convex ridge, second to fifth tergites with a few scattered granules. (After Alcock, 1900.)

Remarks. – Alcock’s (1901: Fig 14; present Fig. 4 ) drawing shows a different number of teeth on the left and right sides for P. indica . On the left side, there appear to be two distinct teeth followed by one granular lobe, while on the right side, there are no distinct teeth matching those on the left. Behind the cervical groove, his figure shows two granular lobes on the right, but none on the left. Clearly, the arrangement and size of teeth on the anterolateral margins is variable.

Alcock (1900) stated that P. indica differed from P. pulchra in having a supraorbital tooth and differed from P. granulata in not having petaloid meri on the second pair of walking legs. However, it is clear from his fig. 14a (present Fig. 4A ) that the merus is at least flattened if not petaloid.

Size. – Maximum size (sex unknown) given by Alcock (1901) was about 15.0 x 15.0 mm. Smaller specimens have a more elongate carapace than larger specimens.

Depth. – Specimens were collected off Sri Lanka between 51–62 m.

Distribution. – Andamans and Sri Lanka ( Ceylon).

Figures

Fig. 4. Petalomera indica Alcock, 1900:A, overall view; B, posterior view of left first walking leg. (After Alcock, 1900: Fig 14, 14a).