Petrolisthes polymitus Glassell 1937

Petrolisthes polymitus Glassell, 1937

(Figs. 69, 70)

Petrolisthes polymitus Glassell 1937: 81, pl. 1, fig. 1.; Haig 1960: 41, pl. 22, fig. 1; Haig 1962: 176; Haig 1968: 57, 61; Gore & Abele 1976: 24; Gore 1982: 18; Werding & Haig 1982: 68; Hickman & Zimmerman 2000: 65, unnumbered colour photograph; García-Madrigal & Andréu-Sánchez 2009: 37, fig. 4F.

Material examined. Panama [Pacific]: 1 female, cl 4.5, cw 4.7 (FLMNH UF 57718), Coiba Is., Isla Afuerita, northeastern bay, 7°42’16.7”N, 81°38’04.4”W, depth 0.5–1 m, shallow subtidal flat with rocks, corals and coral rubble, under rocks and in crevices of coral rubble, leg. A. Anker, 23.02.2018 (fcn PAN-249); 2 ov. females, cl 3.8, cw 3.9 and cl 4.0, cw 4.1 (MZUSP 33956), Las Perlas Is., Isla Bartolomé, depth 0–1 m, in crevices of rocks, dead and living corals, under large rocks on coarse sand, leg. A. Anker, J. Luque, A.R. Palmer & T. Kaji 19.04.2015; 1 ov. female, cl 4.3, cw 4.2 (MZUSP 33453), Punta Mala, rocky intertidal, leg. A. Anker & J.F. Lazarus-Agudelo, 23.03.2015; 1 male, cl 4.0, cw 3.9, 2 ov. females, cl 4.2, cw 4.1 and cl 3.9, cw 3.7 (MZUSP 33454), same collection data as for previous specimen.

Previous records from Panama. Haig (1960, 1962); Gore & Abele (1976).

Distribution. East Pacific: Mexico, Costa Rica, Panama (Coiba Is., Secas Is., Punta Mala, Taboga Is., Las Perlas Is.), Colombia and Ecuador (including Galápagos) (Haig 1960; Gore & Abele 1972; present study).

Ecology. Intertidal and subtidal, presently known depth range: 0–15 m; under rocks, in rock crevices, in dead and living corals (Pocillopora) (Haig 1960; García-Madrigal & Andréu-Sánchez 2009; present study).

Remarks. Petrolisthes polymitus can be readily recognised in the field by its contrasting dark-and-white colour pattern, the dark part varying from dark-brown or almost black to greenish-brown (Figs. 69, 70; see also Hickman & Zimmerman 2000). The younger individuals are less contrasting than adults (or at least with fewer white areas), however, they may be more colourful, with tinges of purple, green and reddish (Fig. 69A, B). The Mexican specimen illustrated by García-Madrigal & Andréu-Sánchez (2009) was photographed shortly after preservation and therefore is reddish-and-white, but still preserving some of its original pattern.