A NEW SPECIES OF TRICHOPELTARION A . MILNE-EDWARDS , 1880 , FROM THE SOUTHWESTERN ATLANTIC ( CRUSTACEA : BRACHYURA : ATELECYCLIDAE )

A new species of Trichopeltarion A. Milne-Edwards, 1880, is described from off coast of Brazil, namely Trichopeltarion pezzutoi n. sp. The new species is compared to its Atlantic congeners, Trichopeltarion nobile A. Milne-Edwards, 1880, and Trichopeltarion intesi (Crosnier, 1981). The record of T. nobile from Brazil should actually be attributed to T. pezzutoi n. sp. The differences between the genera Trichopeltarion and Peltarion Jacquinot, 1847 are discussed.


INTRODUCTION
To face fisheries depletion in coastal areas, a number of Brazilian fisherman have been turning their attention to unexploited deep-sea fishing grounds (see also Perez et al., 2003).Fishing activities recently conducted in Southeastern Brazilian deep-waters have yielded a wealth of decapod crustaceans as side catch.Thanks to the efforts of Paulo Pezzuto, crustacean material caught during several fishing cruises has been stored and sent to the Zoological Museum in São Paulo for study.Among the material received is a new crab species of the genus Trichopeltarion A. Milne-Edwards, 1880.The new species is described herein and compared with its Atlantic congeners.Additionally, comments are provided on the differentiation between the genera Trichopeltarion and Peltarion Jacquinot, 1847.

Trachycarcinus intesi
Type locality: Cabo de Santa Marta, Santa Catarina, off coast of Brazil, between 400 and 500 meters depth.
Description: Carapace subcircular, slightly wider than long, arched transversally, strongly arched longitudi-nally.Front cut into three prominent, forward directed, triangular sharp teeth; central tooth shorter than laterals.Lateral frontal teeth armed with small acute spines (barbs), central tooth with one minute spine on each side.Orbits large, directed laterally.Inner orbital spine separated from tridentate front by deep V-shape notch, 2-3 barbs distally; orbital spine separated from inner orbital by very deep notch, much narrower than preceding one, 3-5 barbs crest its summit, its length extends anteriorly to base of tridentate front; outer orbital spine shorter, triangular in outline, slightly directed outward, separated from orbital spine by a wide notch, barbs on each side.Anterolateral margin rounded, marked with two large triangular spines.First spine longer, separated from outer orbital spine by a subtle depression, barbs becoming smaller toward its tip.Second spine protruding from margin less prominently, armed with barbs, separated from first spine by a weak depression.First and second anterolateral spines and outer orbital spine equidistant from one another.Lateral spine much longer than preceding ones, ending in a acute tip directed laterally, each of its slopes armed with barbs.Posterolateral margin weakly convex, extending obliquely into posterior margin, ornamented with two blunt short spines each one armed with barbs.First and second posterolateral spines more closer to one another than to lateral spine.Posterior margin concave axially, ornamented with several rounded tubercles.Dorsal surface of carapace paved with numerous rounded tubercles, tending to become larger posteriorly, except in depressions bounding elevated regions.Frontal region sparsely tuberculated behind frontal teeth.Gastric region swollen, well delimitated laterally by two well excavated wide smooth grooves.Mesogastric region with axial row of small tubercles.Metagastric and urogastric regions separated by short, shallow, oblique, smooth groove; urogastric regions with larger tubercles.Cardiac region heavily tuberculated, two aggregates of smaller tubercles posteriorly.Branchiocardiac grooves smooth, deeply excavated, sinuous.Intestinal region heavily tuberculated, bounded by two large tubercles crested with conspicuous granules.Hepatic and branchial regions heavily tuberculated.Pterygostomial region granulated, most dense anteriorly.Buccal frame nearly rectangular, somewhat wider anteriorly.Insertions of third maxillipeds placed well apart.
Thoracic sternum ovoid, finely granulated, longer than wide; maximum width attained at somite five.Somite three with two lateral expansions.Pair of tubercles from the press-button system situated in the middle of sternite 5.
Right cheliped extremely well developed, massive.Dactylus minutely granulated, longer and more sharply curved than fixed finger, ending in a short acute tooth; cutting edge armed with blunt teeth.Fixed finger minutely granulated, slightly curved, ending in a short acute tooth; teeth from cutting edge very low, except for two small conical teeth anterior to distal tooth.Propodus minutely granulated, except for a few larger granules on its upper margin.Upper margin of carpus tuberculated proximally, ending in a strong acute spine; carpus outer surface finely granulated, ornamented with clusters of small tubercles.Merus finely granulated except for its upper surface tuberculated proximally.Outer surface of propodus, carpus, and merus of smaller cheliped heavily tuberculated, ornamented with long hairs; upper sur-face of propodus armed with acute spines.Dactyli of all pereiopods longer than propodus, surface thickly velvety; remaining segments with sparse hairs.P5 with long hairs on its upper and lower margins, except for carpus with long hairs dorsally only; coxa heavily tuberculated.Abdomen of both male and female of six free segments and telson.Male abdomen sparsely covered with fine hairs; segments 1-3 with a few tubercles, remaining segments smooth.Sixth male abdominal segment longer than preceding ones, squarish, its anterolateral angles only slightly protruded, weakly swollen; complementary parts of press-button system present and functional.G2 very long, styliform, sinuously curved, crossed near tip.Etymology: This species is named for Paulo Ricardo Pezzuto (Universidade do Vale do Itajaí, Santa Catarina) in recognition of his continuous efforts to secure crustacean specimens caught during commercial deep-water fishing operations.

Distribution:
The species is known from the Brazilian coast (Bahia, São Paulo, and Santa Catarina), between 333 and 500 meters depth.

Remarks:
The genus Trichopeltarion A. Milne-Edwards, 1880, encompasses two valid species in the Atlantic ocean to date, Trichopeltarion nobile A. Milne-Edwards, 1880 (from the Caribbean Sea and Gulf of Mexico, between 274 and 752 meters depth, see Pequegnat, 1970;Poupin, 1994), and Trichopeltarion intesi (Crosnier, 1981), from West Africa (Ivory Coast, 600 meters depth, see Crosnier, 1981).A third Atlantic species is now added to the genus, Trichopeltarion pezzutoi n. sp.Two striking differences between mature males and females of both T. pezzutoi n. sp. and T. nobile are that: (i) in T. pezzutoi n. sp. the carapace is entirely and regularly covered with short sparse fine hairs (while in T. nobile the carapace is covered by a thick coat of velvet, see also A. Milne-Edwards, 1880:20-21;Rathbun, 1930;Salva & Feldmann, 2001:34); (ii) the carapace is regularly covered with rounded tubercles (whereas in T. nobile the carapace is ornamented with small tubercles or granules near the margins while its central parts are smooth).Additional differences between T. pezzutoi n. sp. and T. nobile are as follows: (i) carapace lateral spine neatly shorter in T. pezzutoi n. sp.; (ii) posterior region of the carapace heavily tuberculated (smooth in T. nobile, see also Salva & Feldmann, 2001:30, tab.3); (iii) gastric region clearly delimited by well marked furrows (hardly recognizable in T. nobile); (iv) G2 crossed near tip (G2 crossed well before tip in T. nobile).
The mature female recorded from off coast of Bahia and identified with T. nobile by Tavares & Young (2004) should actually be attributed to T. pezzutoi n. sp.
T. pezzutoi n. sp. and T. intesi are very different from each other.In T. intesi the carapace is heavily ornamented and the front is cut into three cylindrical teeth of equal length, whereas in T. pezzutoi n. sp. the front is expressed as three sharp triangular teeth, the central one shorter than the laterals (see also Crosnier, 1981: fig.1).As suggested by the pronounced heterochely in the small male holotype, T. intesi reach maturity at a much smaller size (at least cl 17 mm, cw 15.5 mm) and seems to be a much smaller species.In T. intesi the antennal article 2+3 is separated from the inner suborbital tooth by a wide gap and is freely mov-able (see also Crosnier, 1981: fig. 2a), whereas in T. pezzutoi n. sp. and T. nobile, the antennal article 2+3 and the inner suborbital tooth are placed close to one another and the antennal article 2+3 is hardly movable.Future researches may prove that T. intesi actually belong to an undescribed genus.
Rathbun (1898) described an additional species from the Gulf of Mexico, Trachycarcinus spinulifer Rathbun, 1898.The description of T. spinulifer was based on one male and a broken carapace, both caught off the delta of the Mississippi River between 592 and 635 meters depth.As interpreted by Rathbun (1898:278-279;1930:166-167) one remarkable trait of T. spinulifer is the nearly equal chelipeds, while in T. nobile "Les pattes antérieures [chelipeds] sont très inégales, celle de droite énorme et presque complètement glabre..." (A. Milne Edwards, 1880:20).Based on many additional specimens of different sizes from the Gulf of Mexico, Pequegnat (1970:184) suggested that the possession of a major cheliped is size related.He concluded that the male holotype of Trachycarcinus spinulifer (carapace 26 mm long, frontal teeth excluded) is an immature of Trichopeltarion nobile (holotype 66 mm long caught at Santa Lucia at 276 meters depth) and placed T. spinulifer in the synonymy of T. nobile accordingly.As suggested from Pequegnat's data and also by Salva & Feldmann (2001:32), tubercles density and carapace ornamentation are also affected by carapace size, as smaller specimens tend to be more heavily ornamented.Based on the examination of the holotype of T. spinulifer we subscribe to the view that T. spinulifer Rathbun, 1898, should merge into the synonymy of T. nobile A. Milne-Edwards, 1880.

Remarks on the genera Trichopeltarion and Peltarion
Ambiguities in assignment of species to Trachycarcinus and Trichopeltarion mainly, but also to Peltarion Jacquinot, 1847, has long been problematic (Rathbun, 1930:165;Richardson & Dell, 1964;Dell, 1969;Takeda, 1973;Crosnier, 1981;Guinot, 1986;1989;Salva & Feldmann, 2001).Traditionally too much emphasis has been placed on carapace outline and shape to differentiate genera.It is therefore not unexpected that generic characters overlap as new species are discovered.Based on several recent and fossil species Salva & Feldmann (2001) concluded that Trachycarcinus Faxon, 1893, should merge into the synonymy of Trichopeltarion.Although they did not elaborate on the differences between Trichopeltarion and Peltarion they pointed out that Peltarion dextrum (Rathbun, 1898) "appears to be similar to Trichopeltarion, especially with regard to the orbital and anterolateral spines".Rathbun (1898:277) had also noticed that Peltarium dextrum resembles Trichopeltarium in certain points.As revealed by Peltarion spinulosum (White, 1843) (= Peltarion magellanicus Jacquinot, 1847, type species of Peltarion), Peltarion differs from Trichopeltarion in having: (i) the male abdominal segments 3 to 5 fused to each other (in Trichopeltarion all abdominal segments are usually free though Salva & Feldmann (2001:43) reported that segments five and six are fused in T. greggi Dell, 1969, from the Miocene of New Zealand; in Peltarion dextrum abdominal segments 1-6 are free); (ii) the two complementary parts of the abdominal holding system well defined but are not functional as the sockets do not reach the thoracic sternal buttons (see also Guinot, 1979;Guinot & Bouchard, 1998) (the two parts of the pressbutton system are present and functional in Trichopeltarion although a gap between the complementary parts may occur in large individuals on the major cheliped side, Guinot & Bouchard, 1998:646; in Peltarion dextrum the two parts of the press-button system are present and functional); (iii) the pair of tubercles of the press-button system are very close to the sternal suture 5/6 (in Trichopeltarion the tubercles are in the middle of sternite 5); (iv) a narrower telson, so the tips of G2 remain exposed laterally when the abdomen is fully folded beneath the cephalothorax (the G2 remain completely hidden in both Trichopeltarion and Peltarion dextrum); (v) the anterolateral angles of abdominal somite 6 strongly protruded forward so the telson show as a narrow triangle intercalated in between (in both Trichopeltarion and Peltarion dextrum the telson is not intercalated within abdominal somite 6 as the postero-lateral angles of the sixth somite are only weakly protruded).A thorough study of P. dextrum is badly needed in order to appropriately evaluate its systematic position.