Petrolisthes lazarus Ferreira & Santana-Moreno & Anker 2020, sp. nov.
Creators: name: Ferreira, Luciane Augusto De Azevedo
name: Santana-Moreno, L. Daniel
name: Anker, Arthur
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Porcellanidae
Petrolisthes
Petrolisthes lazarus

description: Petrolisthes lazarus sp. nov.
(Figs. 1–3)
Type material. Holotype: female, cl 10.8 mm, cw 12.5 mm (MZUSP 33807), Panama, Pacific coast, Las Perlas Islands, small rocky islet off north-eastern coast of Isla Saboga, 8°38’39.5”N– 79°03’43.5”W, rock-sand bottom, 0–1.5 m at low tide, strong current, under rocks and in dead corals, leg. A. Anker, J. Luque, A. R. Palmer & T. Kaji, 22.04.2015. Paratype: ovigerous female, cl 8.5 mm, cw 9.9 mm (MZUSP 33686), Panama, Pacific coast, Río Mar, 8°27’19.2”N– 79°58’09.4”W, rocky intertidal, low tide, under rocks and in rock crevices, leg. A. Anker, J.F. Lazarus-Agudelo & T. Kaji, 20.03.2015.
Description. Carapace subcircular, distinctly wider than long; dorsal surface rugose and sparsely granular. Frontal and orbital regions depressed, rugose. Front about 1/3 width of maximal carapace width; margins granulate, trilobate in dorsal and frontal views, devoid of setae; median lobe broadly subtriangular, distally rounded, slightly overreaching lateral lobes, lateral lobes rounded, somewhat protruding anteriorly. Outer orbital angle well defined, rounded, with granular margin. Orbit with slightly granulate margin. Lateral carapace margin poorly defined by longitudinal row of granules extending posteriorly from epibranchial angle to mesobranchial margin. Protogastric region swollen; epibranchial and hepatic regions swollen, delimited by shallow grooves; epibranchial regions with conspicuous granules, without spines. Epibranchial angle and cervical groove well defined. Posterolateral carapace surface rugose; posterior region depressed; posterior margin concave, devoid of setae. Branchiostegite with longitudinal, subaparallel wrinkles, fringed with long plumose setae; anterodorsal region with slightly projecting, granular crest.
Thoracic sternite 3 with median lobe broad, subtriangular, unarmed, not overreaching lateral lobes; lateral lobes narrow, subtriangular. Thoracic sternites 4–7 broad, sutures between sternites incomplete, distinct only laterally. Thoracic sternite 8 with anterior margin convex, posterior margin concave.
Ocular peduncle subcylindrical dorsally, ventral surface flattened. Cornea small, not dilated.
Antennular basal article unarmed; anterior lateral part slightly concave. Articles 2 and 3 unarmed, subcylindrical, equal in length to each other; article 3 widening distally.
Antennal articles unarmed, slightly granulate. Article 1 acutely pointed anteriorly, with granular margins. Article 2 about half-length of article 3. Article 4 about 1/3 of total length of article 3. Flagellum long, composed of short units with inconspicuous setae.
Mxp 3 with ventral surface rugose. Ischium with lateral lobe narrow, distinct, separated by deep V-shaped incision. Merus as long as ischium; flexor lobe broad, with rounded tip. Exopod lanceolate, fringed with long plumose setae on lateral margin, reaching about half length of merus; flagellum well developed.
P1 equal in size from right to left, subsymmetrical in shape, robust, flattened, granulate dorsally; slightly rugose ventrally. Merus about 1/4 length of carpus; dorsomesial lobe well developed, rounded, up-turned, granular; ventral distomesial spine well developed. Carpus as long as palm, with 4 or 5 blunt, marginally granulate teeth on proximal half of anterodorsal margin; posterodorsal margin somewhat uneven, unarmed. Both palm and carpus with dense field of moderately long plumose setae on lateral (outer) surface. Fixed finger about 1/3 total length of entire chela, equal in length to dactylus. Fingertips curved; cutting edges of fingers granulate, with short setae.
Walking legs decreasing in size posteriorly from P2 to P4, slightly rugose laterally and mesially, densely fringed with long plumose setae dorsaly and ventrally; margins of P2–P4 meri and carpi unarmed; P2–P3 carpi about halflength of P2–P3 meri; P4 carpus about 2/3 length of P4 merus; P2–P4 carpi nearly equal in length to P2–P4 propodi; P2–P4 propodi with 6 or 7 movable corneous spines ventrally, 4 or 5 medially aligned, 2 on distal margin near articulation with dactylus; P2–P4 dactyli about half-length of P2–P4 propodi, ventral margin with row of 3 spines.
Pleon subrectangular, with dorsal surface smooth; lateral margins with dense row of long plumose setae. Configuration of male pleopods unknown. Female pleopods well developed on somites 4 and 5. Uropods broad, reaching distal margin of telson; lateral margins with densely inserted, long plumose setae. Telson smooth on external surface, wider than long, subdivided into 7 plates; lateral margins densely fringed with long plumose setae.
Colour pattern. Carapace mostly brown or pale brown, symmetrically marbled with brown-greenish and pale orange areas, with whitish or pale orange striation; frontal and hepatic areas darker red-brown; cardiac region pale orange with two 2 whitish patches; median posterior region with more or less marked white patches; branchiostegite pale yellow or whitish. Antennule pale brownish, with brown or grey area subdistally. Antenna pale orange-brown; flagellum red-brown. Mxp 3 brown-greenish to greyish dorsally (on interior surface), yellowish ventrally (on exterior surface). P1 dorsal surface pale brown with pinkish or orange tinge dorsally, with some brown spots on merus, carpus and palm, distolateral area of palm and fingers darker brown (more in holotype), except for whitish tips; ventral surface pale orange or pale pink. P2–5 whitish with pale yellow or brownish tinge or pale brown, partly concealed brown by setae. Pleon pale pink on external surface (Figs. 2, 3).
Etymology. The new species is named after our colleague and friend, Dr. Juan Felipe Lazarus-Agudelo (Universidad del Valle, Cali, Colombia) for his invaluable help in the field and for generously sharing his excellent knowledge of the ecology and taxonomy of porcelain crabs, one of his favourite study groups. Used as a noun in apposition.
Distribution. Currently known only from two localities on the Pacific coast of Panama, viz. Las Perlas Islands (Isla Saboga) and Río Mar.
Ecology. Both type specimens of P. lazarus sp. nov. were collected under large rocks on sand-rock bottoms, in the lower rocky intertidal area (Río Mar, Fig. 4) or in the shallow sandy-rocky subtidal area, less than 1.5 m at low tide (Las Perlas Islands).
Remarks. Petrolisthes lazarus sp. nov. is morphologically closest to P. crenulatus (Figs. 5, 6), and to a lesser degree also to P. lewisi (Fig. 8A, B) and P. ortmanni (Fig. 8C). As correctly pointed out by García-Madrigal & Andréu-Sanchez (2009), P. crenulatus can be most easily separated from P. ortmanni by the presence of dense seta- tion on the P1 carpus, in addition to the very clear differences in the proportions of this article, as mentioned and illustrated by Haig (1960). In other words, in P. crenulatus, the carpus is relatively slender and has a dense field of setae along its lateral (outer) surface (Fig. 4, 5), whereas in P. ortmanni, the carpus is noticeably more robust and without dense setation laterally (Fig. 8C). The same is true for P. lewisi, in which the P1 carpus is similarly robust and lacking setation, thereby clearly differing from the P1 carpi of P. lazarus sp. nov. and P. crenulatus. These and several other morphological characters that might be useful in the separation of these four eastern Pacific species are listed in Table 1.
Petrolisthes lazarus sp. nov. is distinguishable from P. crenulatus by the relatively wider carapace, with the frontal width being about 1/3 of the maximal carapace width (vs. approximately 1/ 2 in P. crenulatus); the more strongly protruding frontal lateral lobes; and both the palm and the carpus of P1 fringed with dense plumose setae laterally (vs. only P1 carpus fringed with plumose setae laterally in P. crenulatus). This last character, i.e. the presence of dense field of plumose setae on the lateral (outer) surface of the palm (as well as of the carpus) is the most obvious one, separating P. lazarus sp. nov. at once from P. crenulatus, P. ortmanni and P. lewisi (cf. Figs. 2, 3, 5, 6, 8). In addition, P. lazarus sp. nov. can be separated from P. crenulatus by the much less contrasting colour pattern. Most importantly, P. crenulatus has a very conspicuous, large, bright white area on the post-cardiac region of carapace, contrasting with the brown-orange colour of the remaining carapace (Figs. 5, 6). Such a white area is herein described new species.
at most indicated in P. lazarus sp. nov. (Figs. 2, 3), being not nearly as conspicuous and large as in the Mexican species. In addition, the distolateral area of the palm and fingers of P1 of P. crenulatus are dark red-purple (except for whitish fingertips), contrasting with a paler, orange-brown or greenish palm (Figs. 5, 6). In P. lazarus sp. nov., these areas are also darker (Fig. 2, 3), but not nearly as contrasting as in P. crenulatus (Figs. 5, 6), although more specimens are needed to document the variability of the colour pattern in the new species. It must be noted that the detailed description of the colour pattern of P. crenulatus made by A. Petersen and published by Haig (1960: 111) was possibly based on a relatively young or an unusually pale specimen. Nevertheless, Haig (1960) mentioned the P1 fingers being “light russet with reddish purple tint”. All our specimens from a single locality in Nayarit (Fig. 7) identified as P. crenulatus have a very similar colour pattern (Figs. 5, 6) and are darker than the material described by Haig (1960). Also noteworthy is that the low-resolution colour photographs of P. crenulatus, P. ortmanni and P. lewisi published by García-Madrigal & Abréu-Sanchez (2009) show dead and largely discoloured specimens. Therefore, the colour photographs of these three species provided herein (Figs. 5, 6, 8), as well as of P. lazarus sp. nov. (Figs. 2, 3), should be used as a quick visual reference for future field studies and easy discrimination of living or freshly dead specimens.
description: Published as part of Ferreira, Luciane Augusto De Azevedo, Santana-Moreno, L. Daniel & Anker, Arthur, 2020, A new species of the porcelain crab genus Petrolisthes from the Pacific coast of Panama, with taxonomic notes on closely related species (Decapoda: Anomura Porcellanidae), pp. 576-588 in Zootaxa 4858 (4) on pages 577-587, DOI: 10.11646/zootaxa.4858.4.6, http://zenodo.org/record/4412724