Petrolisthes quadratus Benedict, 1901

Ferreira, Luciane Augusto De Azevedo & Anker, Arthur, 2021, An annotated and illustrated checklist of the porcelain crabs of Panama (Decapoda: Anomura), Zootaxa 5045 (1), pp. 1-154 : 112-114

Petrolisthes quadratus Benedict, 1901

( Figs. 71 , 90F )

Petrolisthes quadratus Benedict, 1901: 134 , pl. 3, fig. 4; Haig 1956: 18; Haig 1962: 179; Chace & Hobbs 1969: 121, figs. 32, 43a; Werding 1977: 204, fig. 23; Rodríguez et al. 2005: 565; Hiller et al. 2006: 553; Poupin & Lemaitre 2014: 21, fig. 4D, E; Diez & Lira 2017: 447 ; Poupin 2018: 151.

Material examined. None from Panama. Extra-limital material. French Antilles: 1 male, cl cw indet. ( FLMNH UF 31974 ), Saint Martin, Sta. STM-024, Pinel Island, 18°06’26.7”N, 63°01’02.2”W, intertidal, leg. M. Bemis, 13.04.2012 (fcn BSTM-0492) .

Previous records from Panama. Haig (1956).

Distribution. West Atlantic: USA (Florida), Mexico, Belize, Cuba, Puerto Rico, Bahamas, N, E and S Less- er Antilles, Panama (Bahía de Caledonia), Colombia and Venezuela (e.g. Werding 1977; Rodríguez et al., 2005; Poupin & Lemaitre 2014; Diez & Lira, 2017; Poupin 2018).

Ecology. Largely intertidal, known depth range 0–1 m; on coral substrate, in tide pools, among rocks and coral rubble, especially common at splash zone on sand near piles of rocks ( Chace & Hobbs 1969; Werding 1977; Poupin & Lemaitre 2014; Poupin 2018).

Remarks. Petrolisthes quadratus belongs to an exclusively American group of species of Petrolisthes with an unarmed carapace, relatively smooth, subrectangular P1 carpi and short, stubby ambulatory legs (P2–P4), which also includes the transisthmian P. tonsorius Haig, 1960 and P. tridentatus Stimpson, 1895 , the recently described western Atlantic P. virgilius Hiller & Werding, 2019 (see below and Fig. 88D ), and a number of eastern Pacific taxa (see also Hiller et al. 2006; Hiller & Werding 2019). The morphological distinctiveness and validity of P. quadratus and P. tonsorius , presumably the most closely related species based on morphological grounds, were discussed by Werding (1977). The two species can be most easily separated from each other by the shape of the P1 carpus and P3 merus, and the proportions of the P2–P4 meri ( Werding 1977).

Chace & Hobbs (1969) provided a detailed description of the colour pattern of P. quadratus from Dominica, whereas Werding (1977) and Poupin & Lemaitre (2014) found P. quadratus to be somewhat variable in colour. Most Werding’s (1977) specimens from Santa Marta, Colombia, were sandy yellowish, with the P1 darker and often with an olive tinge; however, in some individuals, the carapace was speckled with brown spots. Similarly, Poupin & Lemaitre (2014) stated that in the specimens from Guadeloupe, the carapace and P1 may be either brown speckled with white or uniform creamy white sandy pale; the P2–P4 are transversely banded with white and pale brown (see their fig. 4D). The herein illustrated specimens from Saint Martin and Bonaire ( Figs. 71 , 90F ) conform well to the previously described colour patterns (see Poupin & Lemaitre 2014: fig. 4D for the other colour variant). Haig (1956) did not report on the colour pattern of her single female specimen from Bahía de Caledonia, presently the only known record from Panama. However, she noticed that it “differs from the rest of the material examined in having a brush of pubescence on the outer surface of the left hand”, thus leaving some doubts about this record.

Figures

FIGURE 71. Petrolisthes quadratus Benedict, 1901:A, B, extra-limital specimen, male (cl cw indet.) from Saint Martin (FLM- NH UF 31974), dorsal (A) and ventral (B) views [photographs by AA].

FIGURE 88. Some Caribbean Porcellanidae reported from Colombia, in all likelihood also occurring in Panama: A, Madarateuchus vanderhorsti (Schmitt, 1924), male from Santa Marta, Colombia (CRBM-UV), dorsal view [photograph courtesy of Juan Felipe Lazarus-Agudelo]; B, Parapetrolisthes tortugensis (Glassell, 1945), ovigerous female from Utila, Honduras (not deposited), dorsal view; C, Petrolisthes amoenus (Guérin-Méneville, 1855), male from Saint Martin (FLMNH UF 32408), dorsal view, right P1 missing [photographs in B and C by AA]; D, Petrolisthes virgilius Hiller & Werding, 2019, male from Golfo de Urabá, Colombia (CRBM-UV), dorsal view [photograph courtesy of Juan Felipe Lazarus-Agudelo].

FIGURE 90. Some western Atlantic Porcellanidae (all species reported from Panama or Golfo de Urabá at the Panamanian- Colombian border) photographed in situ: A, Neopisosoma angustifrons (Benedict, 1901), Golfo de Urabá, Colombia; B, Neopisosoma neglectum Werding, 1986, Golfo de Urabá, Colombia; C, Pachycheles tuerkayi Werding & Hiller, 2017, Santa Marta, Colombia; D, Petrolisthes jugosus Streets, 1872, Tayrona, Colombia; E, Petrolisthes tonsorius Haig, 1960, blue colour morph, Bonaire; F, Petrolisthes quadratus Benedict, 1901, Bonaire [photographs courtesy of Juan-Felipe Lazarus-Agudelo (A–D) and Marco Faasse (E, F)].