Calcinus orchidae Poupin, 1997
Illustrations. - Holotype shield length 4.5 mm, Marquesas. Shield length 6.0 mm, Marquesas (Eiao). Left chela, outer face. Ocular peduncles, color pattern. Left third pereopod, color pattern.
References. - Calcinus orchidae Poupin, 1997: 707 (type locality, Marquesas).
Calcinus orchidae - Asakura, 2002: 61 (types specimens, Marquesas).
Shield and cephalic appendages. - Ocular scale with a single terminal spine (sometimes with 1 additional spine, unilaterally).
Chelipeds (P1). - Upper margin of right chela tuberculated or spinous. Outer face of left palm regularly convex. Fingers of left chela with pearl-like tubercles on outer face.
Ambulatory legs (P2-P3). - Dactyl of P3 subequal to propodus or slightly shorter (0.71.0). Distal pilosity of P3 dense, forming a brush of setae.
Armament of telson. - Left lobe of telson with several spines disposed on posterior margin only (24). Right lobe with several spines (23).
Coloration. - Shield white or cream (sometimes turning to black on distal 1/3). Ocular peduncle multicolored with narrow ring close to cornea. Detailed coloration of ocular peduncle: black on proximal 3/4 (including a small blue area); blue on distal 1/4. Distal antennular peduncle yellow-orange (turning to black-orange; flagella orange). Distal antennal peduncle yellow-orange (flagellum orange). Chela uniformly colored, often grading to paler distally (black with tip of fingers white;carpus of cheliped black). Ambulatory legs (P2 & P3) with ring(s) (white, black and blue, with shades of orange on articulations).
Habitat. - Intertidal rocky shores.
Geographic distribution. - Marquesas only, French Polynesia. Indo-West Pacific.
Remarks. - This is a sibling species of C. elegans. Calcinus orchidae occurs allopatrically in the Marquesas Islands where it seems to replace the ubiquitous C. elegans, never found in these Islands despite numerous investigations. The two species are mainly separated by color pattern and by subtle morphological differences on fingers of chelae.