Speocarcinus dentatus Brandão, Coelho-Filho & Tavares, 2012, n. sp.
Creators: name: Brandão, Marianna
name: Coelho-Filho, Petronio Alves
name: Tavares, Marcos
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Xanthidae
Speocarcinus
Speocarcinus dentatus

description: Speocarcinus dentatus n. sp.
(Figs. 1 C–E; 3C; 4B, E; 5C; 6C; 7C–D; 8C)
Speocarcinus carolinensis — Bertini et al. 2004: 2200; Vezanni 2007: 100 [not Speocarcinus carolinensis Stimpson, 1859]
Type material. Holotype, male cl 11.5 mm, cw 22.5 mm (MZUSP 12615), Brazil, Ubatuba, Itagiá [Itaguá?], 22.ix.1995. Alagoas, Lagoa Mundaú, iii.1985: 1 male paratype (DOUFPE 6102). Coruripe, F/V Akaroa, st. 76, 10 °02’45’’S– 35°58’00’’W, 4.ix.1965, biogenic bottom, 21 m: 1 female paratype (DOUFPE 6098). Bahia: R/V Calypso, st. 59, 12 °56.5’S– 38°31.5’W, 24.xi. 1961, 20 m: 1 male paratype (MZUSP 23652). Espírito Santo, R/V Prof. W. Besnard, st. RD–66, 18 °39'0''S– 39°41'3''W, 1973, mud, 16 m: 1 male paratype (MZUSP 9124). Rio de Janeiro, Casimiro de Abreu, 22°38'22.1''S – 41°54'10.3''W, 1.iii.2008: 20 males, 37 females paratypes (MZUSP 23653), Baía de Sepetiba, st. 6 VV1, 22 °57.59’S– 43°57.34’W, M. Tavares coll., 6.x.1998, 11.5 m: 1 male, 1 female paratypes (MZUSP 23651), Ilha Grande, R/V Emília, st. 280, 14.vii.1966, 38.2 m: 2 males, 2 females paratypes (MZUSP 11007). São Paulo, Ubatuba, Praia da Enseada, 17.ix.1989: 1 female paratype (MZUSP 9973), São Sebastião, 25.x.1961: 1 male paratype (MZUSP 9939). Santa Catarina, Projeto Sueste I, st. 6090, 26 °14'S– 48°19'W, 1986, sand, 30 m: 1 macho paratype (MZUSP 9073), Porto Belo, shrimp trawler, 7.xi. 2009, 20 m: 4 males paratypes (MZUSP 23649), 6 males paratypes (MZUSP 23650), 12.iii. 2010, 30 m: 1 female paratype (MZUSP 23646), 6 males, 8 females paratypes (MZUSP 23647), 30 males, 29 females paratypes (MZUSP 23648), 24°04.318’S – 48°28.091’W, 19.viii. 2010, 30 m: 1 male paratype (MZUSP 23393). Rio Grande do Sul, Torres, R/V Almirante Saldanha, st. 2234, 30 °37’S– 49°59.6’ W, 18.x.1969, mud and sand, 71 m: 3 males paratypes (DOUFPE 6113); R/V Prof. W. Besnard, st. 1868, 35 °33'S– 53°48'W, 12.viii. 1972, 58 m: 1 male paratype (MZUSP 9030). Locality unknown, 1 female paratype (MZUSP 12628).
Type locality. Ubatuba, Itagiá [Itaguá?], São Paulo, Brazil.
Etymology. From the Latin dentatus for toothed in reference to the carapace anterolateral teeth.
Description of the holotype. Carapace wider than long, maximal width at fifth anterolateral tooth, minutely granular near margins, punctate dorsally, punctations deeper posteriorly; mesogastric, cardiac, and intestinal regions laterally limited by well-defined grooves, cardiac and intestinal groove markedly deeper. Pterygostomian region with distinct transversal row of coarse granules above inhalant channel. Branchiostegal region with distinct, transversal row of granules, densely granular above and below transversal row. Fronto-orbital width distinctly more than half of maximal width of carapace; frontal margin divided by distinct V-shaped median notch; frontal margin dense, coarsely granular; just behind frontal margin secondary transversal row of coarse granules; transverse groove with row of setae extending across between frontal margin and secondary row of granules; frontal area behind secondary row of granules punctate. Supraorbital margin interrupted by 2 small notches, lined with distinct granules, granulation coarsest in lateral half, continued to outer orbital tooth (first anterolateral); suborbital margin lined with small granules, mesially with broadly triangular lobe directed toward front. Anterolateral margin strongly convex, projecting in 4 distinctly granular teeth, decreasing successively in size posteriorly; first (outer orbital) and second teeth completely fused together into single, broad lobe; wide gap between anterolateral teeth 3, 4 and 4, 5 (last anterolateral tooth); anterolateral teeth 1–3 lobate, fourth and fifth strong, spiniform. Posterolateral margins well defined, rather straight behind last anterolateral tooth. Limit between epistome and endostome well defined, forming pronounced, sinuous lip, interrupted by 3 shallow notches, one at each side of mesial notch. Ocular peduncle distinctly flattened dorsally, anterior border granular, freely movable, thick, constricted subdistally, fully retractable into orbital cavity; cornea small, brownish ommatidia well recognizable. Antennules prominent; basal article thickest laterally, with row of transverse granules; second article smooth, elongate, subcylindrical, articulated to basal article at mesial end of antennular fossa; third article nearly equal in length to second, swollen distally, tapered to proximal articulation with second article, terminally with long marginal setae at either side of dorsal flagellum on dorsal side. Antennal article 2+3 immovable, filling orbital gap; articles 4 and 5 freely movable, subcylindrical. Thoracic sternum regularly punctate, pits well apparent; sterno-abdominal cavity scattered granular anteriorly, lateral margins with scattered granules. Abdominal locking system functional, thoracic sternal button placed next to thoracic sternal suture 5/6. Third maxillipeds widely separated from each other; ischium with distinct longitudinal furrow, scarce granules near mesial margin; merus distinctly shorter than ischium, evenly granular. Chelipeds weakly heterochelous. Merus of major P1 trigonal, dorsal margin with ridge of granules of moderate size ending in strong, sharp, subdistal spine, ventrolateral margin granular, granules stronger anteriorly. Carpus with short, blunt spine on inner margin, mesial margin granular, dorsal surface scarcely granular, margins granular. Propodus stout; dorsal and ventral surfaces with rows of few granules and setae. Fingers gaping proximally; cutting edges bluntly dentate proximally, teeth becoming coalescent anteriorly; fingers pinkish throughout length. Ambulatory legs (P2–P5) long, slender, relative lengths P4>P3>P2>P5. Meri of P2–P5 with row of scattered, minute granules dorsally. Carpi and propodi of P2–P4 with rows of dorsal setae, scattered pitted. Dactyls of P2–P5 depressed each with corneous tip and 5 longitudinal rows of long setae, 2 dorsal, 1 ventral, 2 lateral. Abdomen of 4 segments and telson; abdominal segment 2 partially intercalated between edges of abdominal segments 3–5; segments 3–5 fused together; abdominal suture 3/4 distinct, suture 4/5 faint; segment 1 much broader than segment 2 (female abdomen of 6 segments and telson). Distal end of G1 bent as inward curve.
Remarks. The patterns in carapace dentition vary substantially between young and adult individuals of S. carolinensis and, as a result, a number of similar species have been confused with it. Small individuals of S. carolinensis closely resemble S. lobatus, S. monotuberculatus and S. amazonicus in their patterns of carapace dentition (Guinot, 1969; Felder & Rabalais, 1986; Brandão et al., 2010), whereas large individuals of S. carolinensis superficially resemble those of Speocarcinus dentatus n. sp. Because S. carolinensis can exhibit broad variation in carapace dentition and because the largely untested assumption of a widely distributed western Atlantic crab fauna (Coelho and Ramos 1972; Melo 1996; 1998; Boschi 2000), southwestern Atlantic individuals actually belonging to either S. amazonicus (Brandão et al. 2010) or to Speocarcinus dentatus n. sp. have been repeatedly identified as S. carolinensis. The assumption of a widely distributed western Atlantic crab fauna has been challenged on several occasions, particularly when direct comparison between southwestern Atlantic specimens with specimens collected further north, has revealed that southern individuals previously identified as northern species proved to be new to science (Brandão et al. 2010; Manning and Holthuis 1989; Manning et al. 1989; Tavares 1991; 1993; 2011; Tavares and Melo 2005; 2010).
Speocarcinus dentatus n. sp. can be easily separated from S. carolinensis by having (i) a branchiostegal region with a distinct, transversal row of granules (Fig. 3C), whereas in S. carolinensis the branchiostegal region has patches of dispersed granules (Fig. 3B); (ii) the ocular peduncle is distinctly granular (Fig. 4B), whereas in S. carolinensis the ocular peduncle is smooth (Fig. 4A); (iii) the dorsal and ventral surfaces of the P1 propodus have rows of a few granules and setae, whereas in S. carolinensis the P1 propodus has scattered granules only; (iv) the male abdominal segment 2 is partially intercalated between edges of abdominal segments 3–5 (Fig. 6C), whereas in S. carolinensis the male abdominal segment 2 is free, not intercalated between the edges of abdominal segments 3–5 (Fig. 6B).
Speocarcinus dentatus n. sp. can be distinguished from S. lobatus by: (i) the branchiostegal region is densely granular above and below the transversal row of granules (Fig. 3C), whereas in S. lobatus the region is smooth above and immediately below that row (Fig. 3D); (ii) the dorsal and the ventral surfaces of the P1 propodus have rows of a few granules and setae, whereas in S. lobatus the P1 propodus is nearly smooth; (iii) a wide gap between anterolateral teeth 3 and 4 and 4 and 5; the anterolateral teeth 1–3 are lobate, and teeth 4 and 5 are strong and spiniform (Fig. 1 C), whereas S. lobatus has a narrow gap between the anterolateral teeth 3 and 4 and 4 and 5 (last anterolateral tooth); the anterolateral teeth 1–4 are lobate, and the fifth short and truncate (Fig. 2 C).
Speocarcinus dentatus n. sp. differs from S. granulimanus and S. spinicarpus by a P1 carpus with a short and blunt tooth on its inner margin (fig. 1C), whereas in S. granulimanus and S. spinicarpus the tooth on the inner margin of P1 carpus is remarkably strong (Figs. 2B, F).
The new species lacks a dorsal median tubercle on abdominal segment 2 (Fig. 6C), whereas the male and female abdominal segment 2 of S. monotuberculatus is provided with one dorsal median tubercle. The distal end of the G1 of the new species is bent as an inward curve (Fig. 7C) and the vulva is transversely oriented in relation to the median line of the thoracic sternum (Fig. 8C), whereas in S. amazonicus and S. meloi the distal end of G1 is similarly bent as an inward curve but its is also bent towards the interior of the sterno-abdominal cavity (Fig. 7A) and the vulva is obliquely oriented in relation to the median line of the thoracic sternum (Fig. 8A).
In S. dentatus n. sp. the punctations and granulations of the chelipeds are more apparent in young than in adults.
Relying on the literature alone (Rathbun, 1918: 39, pl. 159, fig. 6; Williams, 1965: 203, fig. 186) Fausto-Filho and Sampaio Neto (1976) identified one male from Amapá (03o31’N – 48o19’W) as S. carolinensis. Although we have not been able to examine the specimen, we believe that it should be tentatively referred to S. dentatus n. sp. because the new species is so far the only one in the area having a carapace dentition that matches that of an adult S. carolinensis as figured by Rathbun (1918) and Williams (1965).
Distribution. Brazil (Alagoas, Bahia, Espírito Santo, Rio de Janeiro, São Paulo, Santa Catarina, Rio Grande do Sul), 11– 71 m.
description: Published as part of Brandão, Marianna, Coelho-Filho, Petronio Alves & Tavares, Marcos, 2012, A review of the genus Speocarcinus Stimpson, 1859 (Crustacea: Brachyura: Xanthidae), with a key to its species and the description of one new species, pp. 1-19 in Zootaxa 3327 on pages 12-14, DOI: 10.5281/zenodo.210554