Cryptodromia pileifera Alcock, 1901

Mclay, Colin L. & Ng, Peter K. L., 2005, On a collection of Dromiidae and Dynomenidae from the Philippines, with description of a new species of Hirsutodynomene McLay, 1999 (Crustacea: Decapoda: Brachyura), Zootaxa 1029 (1), pp. 1-30 : 9-10

Cryptodromia pileifera Alcock, 1901 ( Fig. 3 )

Dromia (Cryptodromia) tuberculata var. pileifera Alcock, 1900: 141 .

Cryptodromia tuberculata var. pileifera — Ihle 1913: 36, 20 (list).— Buitendijk 1939: 225.— Buitendijk 1950: 60.— Daniel & Premkumar 1968: 240.

Cryptodromia pileifera .— Alcock 1901: 49, pl. 2: fig. 7.— Tan & Ng, 1988: 88.— Tan et al. 1986:

111.—McLay 2001: 828 (key).

Cryptodromia tuberculata .— McLay 1993: 198.— Lim et al. 1994: 126 [not Cryptodromia tuberculata Stimpson, 1858 ].

Material. 1 male, 6.6 x 5.8 mm, station D8, Santiago, Panglao , Bohol, Philippines, 9°0.034'N 123°0.049'E, substrate sandy bottom, seagrass, rubble and coral slabs, coll. PANGLAO Expedition 2004, 9 Jun 2004, ZRC ; 1 ovigerous female, 6.3 x 5.6 mm, station M8, Doljo , north coast, Panglao, Bohol, Philippines, 9°0.035'N 123°0.044'E, rocky flat with seagrass, rocks and mangroves, coll. PANGLAO Expedition 2004, 2 Jun 2004, NMCR .

Remarks. A useful character that can be used to identify this species when live or freshly preserved is the presence of a pink band running medially across the outer surface of the cheliped fingers. Even in preserved material some vestige of the bands usually remains visible. This band is absent on C. tuberculata .

The ovigerous female was carrying 11 newly hatched curled up and apparently freshly hatched zoeae (diameter ca. 1.05 mm). Tan et al. (1986) reported that C. pileifera had a very abbreviated larval development, with the first zoea being lecithotrophic and metamorphosing into the megalopa in a short time. This study was conducted in the laboratory (based on a Singapore female) and on the basis of the present Philippine female, this species may actually hold the newly hatched first zoeae for a longer period than had previously been assumed. In any case, the first zoeae reported by Tan et al. (1986) were slow moving and hardly swam.

Daniel & Premkumar (1968) reported a study of the use of sponges for camouflage by C. pileifera collected in the intertidal of Great Nicobar Island. Crabs separated from their sponge caps in small bowls recovered themselves with the same caps within two hours. In another experiment in which the crabs were deprived of their caps and supplied with live sponges, they “broke off” pieces and carried them with the last pair of legs. When the crabs were provided with simple ascidians, empty bivalve shells and encrusting sponges they only donned pieces of sponge. The authors argue that the crabs take advantage of the “disagreeable taste and odour as well as the bristly spiculation” of the sponges that are seldom eaten by other animals and, in return, the sponges benefited by being “carried from place to place and also obtain small particles of food scattered about by the crabs”. They found that the largest males and females measured 10.5 x 8.5 mm, which is similar to those we have examined from Singapore and nearby areas. All the specimens we have examined or observed in life from Singapore, Malaysia and Indonesia, however, use colonial tunicates instead as a cover, not sponges. The crabs live among rocky substrates with the tunicates neatly cut out to fit exactly the carapace shape and size (see Tan & Ng 1988, Lim et al. 1994). They are never found with any other object on their back.

Distribution. Cryptodromia pileifera is a widespread species in Southeast Asia and India (see Tan et al. 1986), and while its presence in Philippines constitutes a new country record, it is not surprising as it is often common in near­shore and intertidal habitats.

Figures

FIGURE 3. Cryptodromia pileifera Alcock, 1901. Male, 6.6 x 5.8 mm, Panglao, Philippines, ZRC. A, overall dorsal view; B, frontal view; C, outer view of right chela.