Balssiathelphusa phasma, Ng & Guinot, 2014

Ng, Peter K. L. & Guinot, DaniÈle, 2014, A new cavernicolous species of crab of the genus Balssiathelphusa Bott, 1969 (Crustacea, Brachyura, Gecarcinucidae) from eastern Borneo, Zoosystema 36 (3), pp. 623-629 : 624-628

publication ID	https://doi.org/ 10.5252/z2014n3a4
persistent identifier	https://treatment.plazi.org/id/5235B22E-4E7A-9D33-FF0A-FB345CE6FC59
treatment provided by	Felipe
scientific name	Balssiathelphusa phasma
status	sp. nov.

Treatment

Balssiathelphusa phasma View in CoL n. sp.

( Figs 1-3 View FIG View FIG View FIG )

TYPE MATERIAL. — Holotype. Indonesia, Expédition Spéléologique à Bornéo,main gallery of Gua Kambing , Mount Batu , Mangkalihat Peninsula , east Kalimantan, 1°09.444’N, 117°28.479’E, 454 m asl, J. Lips coll., 21.VII.2002, 1 ♂, 23.1 × 18.9 mm, (MNHN-IU-2013-13148). GoogleMaps

Paratypes. Same data as holotype, 1 ♂ damaged, carapace cracked, all appendages detached, 18.1 × 15.1 mm, 1 ♂ dismembered, badly damaged, carapace detached, sternum broken, all appendages detached, damaged, 23.5 × 18.8 mm, ( ZRC 2014.0092).

ETYMOLOGY. — The species name “phasma” is derived from the Latin for “spirit”, alluding to the ghost-like

appearance (pale coloration and elongated pereopods) of the species. The name is used as a noun in apposition.

TYPE LOCALITY. — Eastern Kalimantan, Borneo, Indonesia.

DISTRIBUTION. — Known only from the type locality.

COLOUR. — An overall pale yellow when freshly preserved.

DIAGNOSIS. — Carapace subovate, broader than long ( Fig. 1A, B View FIG ); epigastric cristae low, rugose, without sharp cristae; postorbital cristae barely discernible ( Fig. 1A, B View FIG ). Frontal margin distinctly sinuous ( Fig. 1A, B View FIG ); frontal median triangle distinct ( Fig. 1C, D View FIG ); external orbital tooth acutely triangular, separated from anterolateral margin by V-shaped cleft ( Fig. 1A, B View FIG ); epibranchial tooth distinct; anterolateral margin distinctly convex ( Fig. 1A, B View FIG ); chelipeds elongate ( Fig. 1A View FIG ); ambulatory legs very long, margins of meri subcristate, gently serrated, without subdistal spine or tooth ( Figs 1A View FIG ; 2D View FIG ); abdomen distinctly T-shaped, somite 6 longer than broad with distinctly concave lateral margins; telson longer than broad, shorter than somite 6 ( Fig. 2 View FIG A-C); G1 slender, subterminal segment gradually tapering with distal half relatively stout; terminal segment short, c. 0.18 times length of subterminal segment, conical, gently curving upwards ( Fig. 3 View FIG A-C); G2 c. 0.8 times length of G1, distal segment short, c. 0.1 times length of basal segment ( Fig. 3D View FIG ).

DESCRIPTION

Carapace subovate, broader than long; dorsal surface gently convex; areas adjacent to antero- and posterolateral margins covered with distinct oblique striae, rest of surface relatively smooth, glabrous ( Fig. 1A, B View FIG ). Regions discernible, cervical grooves distinct, relatively deep, joining distinct H-shaped median depression ( Fig. 1A, B View FIG ). Epigastric cristae low, rugose, without sharp cristae, separated by deep Y-shaped groove; postorbital cristae barely discernible ( Fig. 1A, B View FIG ). Frontal margin distinctly sinuous, separated by shallow; gradually confluent with supraorbital margin ( Fig. 1A, B View FIG ); frontal median triangle distinct, lateral margins distinctly cristate, dorsal margin sharp but not distinct, formed by bend and series of sharp striae ( Fig. 1C, D View FIG ). Supra- and infraorbital margins entire, finely granular to smooth ( Fig. 1A, B View FIG ). External orbital tooth prominent, acutely triangular; inner margin confluent with supraorbital margin; outer margin gently sinuous; separated from anterolateral margin by distinct V-shaped cleft ( Fig. 1A, B View FIG ). Epibranchial tooth distinct; anterolateral margin distinctly convex, lined with small rounded granules, striae ( Fig. 1A, B View FIG ). Posterolateral margin gently sinuous, distinctly converging towards gently concave posterior carapace margin ( Fig. 1A, B View FIG ). Sub-branchial, suborbital, subhepatic, pterygostomial regions granulated, rugose ( Fig. 1C View FIG ). Antennules folding transversely ( Fig. 1C View FIG ). Anterior margin of epistome straight; posterior margin with broadly triangular median lobe with rounded tip, lateral margins sinuous, margins around efferent channels deeply concave ( Fig. 1C, D View FIG ). Third maxillipeds relatively smooth, almost glabrous except for inner margins; merus with median depression, anteroexternal margin rounded but not auriculiform; ischium quadrate, longer than broad, with distinct slightly oblique submedian sulcus; exopod slender, reaching to midpoint of merus, with long multiarticulate flagellum ( Fig. 1E View FIG ). Mandibular palp with bilobed terminal segment.

Thoracic sternum relatively smooth; relatively narrow transversely ( Fig. 2A View FIG ). Somites 1-4 completely fused, without trace of median sutures; surface of sternite 3 medially depressed; sternoabdominal cavity relatively deep, reaching to imaginary line joining anterior margin of coxae of chelipeds ( Fig. 2A View FIG ). Male abdominal locking mechanism with rounded tubercle on median part of sternite 5.

Chelipeds elongate; chelae asymmetrical, right slightly larger; outer surfaces rugose ( Figs 1A View FIG ; 2E, F View FIG ). Basis-ischium squarish, anterior margin with low granules. Margins of merus lined with sharp granules, with distinct subdistal sharp tooth on anterior margin ( Fig. 1A View FIG ). Outer surface of carpus with small sharp granules; inner distal angle with long sharp spine, outer margin lined with small sharp granules ( Fig. 1A View FIG ). Chela relatively slender; outer surface covered with small sharp granules (especially on margins) or rugose; fingers longer than palm, curved distally to corneous tip, cutting edges with small teeth, denticles ( Figs 1A View FIG ; 2E, F View FIG ).

Ambulatory legs very long, second pair longest; outer surface rugose ( Figs 1A View FIG ; 2D View FIG ). Dorsal, ventral margins of meri subcristate, gently serrated with low, uneven granules of differing sharpness; subdistal angle distinct but not armed with spine or tooth ( Figs 1A View FIG ; 2D View FIG ). Carpus elongate, lateral margins covered with very small sharp granules, with low submedian crista on outer surface ( Fig. 2D View FIG ). Propodus subrectangular, elongate, with small sharp granules on margins ( Fig. 2D View FIG ). Dactylus very long, slightly downcurved, with numerous strong, anteriorly directed spines on dorsal, ventral margins; tip corneous.

Abdomen distinctly T-shaped ( Fig. 2 View FIG A-C). Somite 1 very narrow longitudinally, reaching to base of coxa of fourth ambulatory leg; somite 2 broadly rectangular, reaching to base of coxa of fourth ambulatory leg; somite 3 broadly subrectangular with distinctly convex lateral margins, entirely covering thoracic sternite 8 when closed ( Fig. 2C View FIG ); somites 4 trapezoidal with gently convex to straight lateral margins ( Fig. 2B, C View FIG ); somite 5 subquadrate with concave lateral margins ( Fig. 2B View FIG ); somite 6 longer than broad, lateral margins distinctly concave ( Fig. 2A, B View FIG ). Telson triangular, longer than broad, lateral margins gently concave; shorter than somite 6 ( Fig. 2A View FIG ).

G1 slender, gently sinuous; subterminal segment gradually tapering with distal half relatively stout; terminal segment short, c. 0.18 times length of subterminal segment, conical, tapering to sharp tip, gently curving upwards in situ, surfaces covered with numerous long setae which do not obscure margins ( Fig. 3 View FIG A-C). G2 c. 0.8 times length of G1; basal segment long; distal segment short, c. 0.1 times length of basal segment ( Fig. 3D View FIG ).