Pachycheles laevidactylus Ortmann, 1892

Miranda, Ivana, Schubart, Christoph D. & Mantelatto, Fernando L., 2014, Morphological and molecular data support the distinctiveness of Pachycheles laevidactylus Ortmann, 1892 and Pachycheles chubutensis Boschi, 1963 (Anomura, Porcellanidae), Zootaxa 3852 (1), pp. 118-132 : 121-124

Pachycheles laevidactylus Ortmann, 1892

( Figs. 1 A–C)

Pachycheles laevidactylus Ortmann, 1892: 266 , pl. 12, fig. 1.— Melo, 1999: 227, 236, fig. 158.— Coelho, 1963: 64.— Coelho & Ramos, 1972: 173.—Coelho et al., 2007: 8.—Werding et al. 2003: 80, 81, 82.— Rodríguez et al., 2004: 291, 301, 302–305, 307; 2005: 545, 546, 554, 555, 572, 574.— Osawa & McLaughlin, 2010: 112, 116.— Macedo et al. 2012: 185, 188, 189–193.

Pachycheles grossimanus .— Ortmann, 1897: 292.— Haig, 1955: 43 –44; 1960: 167, pl. 35, fig. 1 (part) (see Harvey & De Santo 1966). [Not P. grossimanus (Guérin & Méneville, 1835) ].

Pachycheles haigae Rodrigues da Costa, 1960: 21, figs. 1–4.— Boschi, 1963: 31, figs. 1, 3; 1979: 137; 1981: 735.— Boschi et al., 1967: 6; 1992: 56.— MacMillan, 1972: 57, 67, 68.— Gore, 1977: 299.— Bremec & Cazzaniga, 1984: fig. 2.— Da Silva et al., 1989: 134 –135, figs. 2, 11.— Veloso & Melo, 1993: 173, 177, 183, 184.— Harvey & De Santo, 1996: 710 –713, fig. 2.— Ko, 1999: 130.— Kornienko, 2005: 57.— Bracken-Grissom et al., 2013: 7.

Type locality. Unknown (probably Brazil). The syntypes of Pachycheles laevidactylus (1 male with 9.0 mm carapace length, 1 female with 8.4 mm carapace length) are in the Musée Zoologique de l’Université Louis Pasteur et de la Ville de Strasbourg ( France) ( MZS 380) ( Ortmann 1892). Not examined.

Material examined. 3 females, 2 males ( MNRJ 4096), Ilha de São Francisco, Ubatuba, SP, Brazil, coll. Hans, D., unknown.1949, det. Unknown; 1 female, 6 males ( CCDB 653), Ilha do Prumirim, Ubatuba, SP, Brazil, coll. Mantelatto, F.L. & A. Fransozo, Jul.2002; 1 female, 2 males ( CCDB 2379), Praia Grande, Ubatuba, SP, Brazil, coll. Mantelatto, F.L. & A.S. Costa, Jun.2008; 1 female, 3 males ( CCDB 3048), coll. Mantelatto, F.L., 25.Sep.2002; 1 female, 1 male ( CCDB 676), Itaguá, Ubatuba, SP, Brazil, coll. Mantelatto, F.L., Dec.1995; 1 female, 1 male ( CCDB 2390), Itaguá, Ubatuba, SP, Brazil, coll. Mantelatto, F.L. & D.F. Peiró, 03.Jul.2008; 1 female, 1 male ( CCDB 1933), Praia Cabeçudas, Itajaí, SC, Brazil, coll. Mantelatto et al., Mar.2007; 1 female, 1 male ( CCDB 1936), Praia Brava, Itajaí, SC, Brazil, coll. Mantelatto et al., Mar.2007; 1 female ( CCDB 1935), Praia do Sambaqui, Florianópolis, SC, Brazil, coll. Mantelatto et al., Apr.2007; 1 female ( CCDB 1934), Praia da Conceição, Bombinhas, SC, Brazil, coll. Mantelatto et al., Mar.2007; 2 males (CCFurg 387), Itapema, Porto Belo, SC, Brazil, col.: Felipe, J., Feb.1967; 2 females, 2 males (CCFurg 1052), Rio Grande do Sul, RS, Brazil, coll. Souza, J.A. & A. Martins, 14.Nov.1988; 4 females, 2 males ( CCDB 1845), Mar del Plata, Argentina, coll. Scelzo, M.A., Jun.2006; 7 females, 10 males ( CCDB 3047), Playa Torrion del Monje, Mar del Plata, Argentina, coll. Chiaradia, N., Jul.2008.

Diagnosis. Front triangular in dorsal view; dorsal surface with tuft of setae. Lateral margins of carapace consisting of one large anterior piece, one large posterior piece and usually several small posterior fragments. Basal segment of antennule armed with 2–5 strong spines on medial anterior margin, and 7 or 8 on the anterolateral dorsal surface. Carpus and manus of chelipeds with posterior submarginal furrow, scattered long setae, and small granules. Carpus with anterior crest divided into broad proximal tooth and acute subdistal tooth; dorsal surface with 3 lateral longitudinal ridges, each topped with row of enlarged, elongated, granular tubercles near base of pollex. Walking legs with setose margins. Telson consisting of 5 plates. Second pleopods present in males.

Redescription. Carapace. Carapace about as broad as long in males, convex in lateral view; posterolateral margins convex; dorsolateral ridges pronounced; dorsal surface with posterolateral regions plicate, nearly naked except for tuft of short plumose setae on frontal and post-orbital regions and some long and sparse plumose setae; posterior margin curving inward medially. Front triangular in dorsal view, trilobate in frontal view; median lobe projecting farther than lateral lobes. Outer orbital angle produced into an acute tooth, inner orbital angle slightly pronounced, sometimes continuing as curved crest, constituting accentuated angle with lateral carapace borders. Orbits deep and broad, well defined; eyes large. Lateral margins of carapace consisting of 1 large anterior piece and usually, 1–4 small posterior fragments, varying in size and configuration.

Antennule. Basal segment of antennule armed with 2–5 spines on medial anterior margin (visible from dorsal view), with 7 or 8 spines on anterolateral dorsal surface, dorsal surface with two transverse granular lines.

Antenna. Basal segment of antenna with projection on the anterior margin, configuring together with the border of orbits a well defined cavity for the eyes. Second segment with tubercle on anterior margin; third segment granular, sometimes more pronounced near distal and proximal margins; flagellum with minute setae.

Third maxillipeds. With moderately deep trilobate sternite; median lobe of sternite equaling or slightly exceeding lateral lobes in length; ischium with medioproximal angle only slightly obtuse, almost right angled, merus with pronounced medial lobe, subquadrate in shape and usually dentate anteriorly.

Pereiopod 1 (Chelipeds). Chelipeds unequal in size. Merus wrinkled transversely, with short plumose bristles emerging from it; granular tooth on anterior margin projecting about as far as carpus teeth; ventral margin of merus distinct, ventrodistal angle usually with two small granules; long and plumose setae sometimes present, especially on the external margin. Carpus and manus with weak submarginal furrow on posterior margins; with very short, often vestigial, plumose setae arising in groups from distal side of larger granules. Carpus with crest on anterior margin, divided by notch into broad proximal tooth and somewhat acute subdistal tooth; dorsal surface covered with small granules, more pronounced near posterior margin; surface with three longitudinal ridges, each topped with a row of enlarged granules; one ridge is medial, the other two closely together between medial ridge and lateral margin; dorsal surface with few long, plumose and sparse setae, sometimes distributed along the longitudinal ridges. Manus covered with small granules, especially on outer borders; large, elongated, granular tubercle present near base of pollex; fingers with small, flattened granules on minor chela, nearly smooth on major. Major manus nearly lacking pubescence dorsally; ventral surface of manus with tuft of setae at base of fingers; pollex pubescent, with single medial tubercle on cutting edge; dactyl pubescent on distal half, cutting edge with basal tubercle; fingers gaping, crossing at tips. Minor chelipeds with at most trace of setation on dorsal surface, outer margin with long bristles; fingers meeting entire length of cutting edge, crossing at tips.

Pereiopods 2–4. Pereiopods 2–4 follow the same morphological pattern, with scattered setae on anterior margins of merus, carpus and propodus, setae present also on lateral margins of carpus and propodus. Third pereiopods usually presents more setae which decrease towards the first pereiopod. Propodus with 3 or 4 moveable spines ventrally, 2 distal, 1 subdistal and 1 or 2 medial proximal; dactyl with three corneous spines along ventral margin. Fourth pereiopod smooth, carpus with lines of long and simple setae on dorsal, ventral and lateral surfaces brush-like.

Abdomen. Smooth, with scattered setae.

Telson . Telson with 5 plates in males and females.

Pleopods. Second pair of pleopods present in males.

Measurements. Males with carapace width 2.8–10.9 mm, females 3.3–7.8 mm.

Color. In general, dark-brown with pale yellowish spots on the carapace surface. Tips of fingers ranging from pale yellow to white.

Ecology. Pachycheles laevidactylus is frequently found abundantly on rocky substrates on the infralittoral region, associated to algal discs, mussel communities as Brachyodontes rodriguezi (d´Orbigny, 1846), buoies encrusted by mussels ( Boschi 1963; Boschi et al. 1979; Melo 1999; Scelzo et al. 2008) and inhabiting Phragmatopoma caudata (Kröyer, 1856) sand reefs also in high densities, coexisting with other species of porcelain crabs (see Micheletti-Flores & Negreiros-Fransozo 1999 for more information). According to Micheletti- Flores & Negreiros-Fransozo (1999), P. laevidactylus can be considered the dominant porcelain crab inhabiting sabellariid worm reefs. The species can also be found associated to Schizoporella errata (Walters, 1878) at Ubatuba, SP, Brazil, coexisting with P. monilifer (Dana, 1852) , but in lower densities ( Mantelatto & Souza-Carey 1998; personal observation). Pinheiro & Fransozo (1995) have studied reproductive aspects of this species on the coast of the state of São Paulo, Brazil.

Remarks. The dimension in size and configuration of the lateral walls of the carapace are extremely variable, including right and left side of the same animal. In our observations, the basal segment of the antennule presents two to five spines on the medial anterior margin. Harvey & De Santo (1996) had observed this configuration in the type male that, according to them, has two spines on the right basal antennular segment, three on the left. We extend here the number of spines found on the anterolateral dorsal surface of the first antennule segment from two to four to seven to eight spines. Previous reviews cited for the pereiopods one small tubercle and two distal granules on the margin of carpus which were not observed in the present work. We also found three to four spines ventrally on the propodus, differing from the pattern previously described with four spines.

Distribution. Brazil (from Pernambuco to Rio Grande do Sul) ( Da Silva et al. 1989; Melo 1999), Uruguay to San Antonio Oeste, Argentina ( Harvey & De Santo 1996; Melo 1999; Scelzo et al. 2008); intertidal to 12 m.

Figures

FIGURE 1. Pachycheles laevidactylus Ortmann, 1892. A) General dorsal view (female, CCDB 1933); B) Minor cheliped (dorsal view); C) Telson with 5 plates (ventral view). Scale bar in A) = 1 cm.