Petrolisthes nobilii Haig, 1960

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 : 103

Petrolisthes nobilii Haig, 1960

( Figs. 63–65 )

Petrolisthes nobilii Haig 1960: 55 , pl. 1, pl. 18, fig. 3; Hag 1968: 62; Gore & Abele 1974: 567; Gore & Abele 1976: 23; Gore 1982: 17; Werding & Haig 1982: 67; Lazarus-Agudelo & Cantera-Kintz 2007: 230; García-Madrigal & Andréu-Sánchez 2009: 36, fig. 4D.

Petrolisthes politus .— Nobili 1897: 4; Rathbun 1910: 600 [not Petrolisthes politus (Gray, 1839) ].

Material examined. Panama [Pacific]: 1 ov. female, cl 6.3, cw 6.4 ( FLMNH UF 57715 ), Azuero Peninsula, Puerto Cañas estuary, 7°25’53.8”N, 80°16’01.6”W, under wood log on mangrove mudflat during low tide, leg. A. Anker, 15.02.2019 (fcn PAN-017) ; 1 male, cl 10.6, cw 10.2 ( MZUSP 33888 ), Las Perlas Is., Isla Contadora, east end of Playa Galeón , intertidal, under rocks and in rock crevices, leg. A. Anker, J. Luque, A.R. Palmer & T. Kaji, 16.04.2015 ; 1 male, cl cw indet., ULLZ/USNM, Bahía Chame , leg. J. Scioli , 08.2018 [examined by J. Scioli]. Extra-limital material. Mexico [Pacific]: 1 male, cl cw indet., CNCR, Nayarit, La Cruz de Huanacaxtle , 20°44’43.2”N, 105°22’58.5”W, rocky intertidal, low tide, under rocks, leg. L.D. Santana-Moreno, 24.05.2020 ; 2 males, cl cw indet., CNCR, Nayarit, La Cruz de Huanacaxtle , 20°44’43.2”N, 105°22’58.5”W, rocky intertidal, low tide, under rocks, leg. L.D. Santana-Moreno, 24.06.2020 [all examined by L.D. Santana Moreno].

Previous records from Panama. Nobili (1897, as P. politus ); Haig (1960, 1968); Gore & Abele (1974); Gore & Abele (1976).

Distribution. East Pacific: Mexico, Nicaragua, Costa Rica, Panama (Azuero Peninsula, Jicarita I., Bahía Honda in Veraguas, Bahía Chame, vicinity of Ciudad de Panamá, Panama Canal area, Taboga Is., Las Perlas Is.), Colombia and Ecuador ( Haig 1960, 1968; Gore & Abele 1974, 1976; García-Madrigal & Andréu-Sánchez 2009; present study).

Ecology. Intertidal and shallow subtidal, known depth range 0–15 m; on rocky shores and mudflats with rocks, typically under rocks, wood logs and other debris, among algae ( García-Madrigal & Andréu-Sánchez 2009; present study).

Remarks. Petrolisthes nobilii is phylogenetically close to the western Atlantic P. politus ( Gray, 1831) (see below), these two taxa sharing the carapace being broadest in its posterior portion and lacking epibranchial tooth. However, P. politus differs from P. nobilii by several characters, such as the absence of a narrow line of pubescence on the proximal half of the P1 palm and the gape of the P1 fingers usually without pubescence or with pubescence on only one of the chelipeds ( Haig 1960). Among the eastern Pacific taxa, P. nobilii seems to be most closely related to P. armatus , occupying much the same ecological niche as the latter species; in fact, the two species may often be found syntopically.

The colour pattern of P. nobilii seems to be consistent throughout its range, despite some variation, especially in younger individuals ( Figs. 63–65 ). The most diagnostic features of the colouration of P. nobilii are the dark greenish or green-brown carapace speckled with small yellowish dots and larger dark brown dots, and the similarly speckled meri of the ambulatory legs (P2–P4); their propodi, however, banded with brown and white. The chelipeds (P1) can be speckled in younger individuals or more uniform dark purplish-green in adults. Some young crabs may have a Π-shaped white patch on the carapace ( Fig. 64A ). The specimen from the Gulf of California illustrated by García- Madrigal & Andréu-Sánchez (2009) photographed post-mortem is clearly discoloured; however, the characteristic dark spots of the carapace remain clearly visible. In respect to colour pattern, the Mexican specimens ( Fig. 65 ) are very similar to the Panamanian specimens ( Fig. 63 , 65 ), suggesting that they belong to the same, widespread species.

Figures

FIGURE 63. Petrolisthes nobilii Haig, 1960: A, B, male (cl 10.6 mm, cw 10.2 mm) from Las Perlas Islands, Panama (MZUSP 33888), dorsal (A) and ventral (B) views [photographs by AA].

FIGURE 64. Petrolisthes nobilii Haig, 1960: A, ovigerous female (cl 6.3 mm cw 6.4 mm) from Azuero Peninunsula, Panama (FLMNH UF 57715), dorsal view [photograph by AA]; B, female (cl cw indet.) from Chame Bay, Panama (ULLZ/USNM), dorsal view [photograph courtesy of Justin Scioli].

FIGURE 65. Petrolisthes nobilii Haig, 1960: A–C, male from Nayarit, Mexico (CNCR), dorsal (A), ventral (B) and frontal (C) views [photographs courtesy of Luis Daniel Santana Moreno].