Sundathelphusa spelaeophila, Stasolla & Abbarchi & Innocenti, 2015

Stasolla, G., Abbarchi, A. & Innocenti, G., 2015, Sundathelphusa spelaeophila, a new species of cavernicolous crab from Samar, Philippines (Decapoda: Brachyura: Gecarcinucidae), Raffles Bulletin of Zoology 63, pp. 448-453 : 449-451

Sundathelphusa spelaeophila n. sp.

( Figs. 1A–C , 2A–E )

Material examined. Holotype: male (15.9 × 14.1 mm) ( MZUF 3920 ); Philippines, Samar province, San Jorge municipality, Barangay Matalud, Can Gortio Cave , coll. C. Ferron, 19 March 1991 . Paratypes: 1 male (11.7 × 10.6 mm) ( MZUF 4273 ) Samar province, San Jorge municipality, Barangay Matalud, Can Gortio Cave , coll. C. Ferron, 19 March 1991 ; 1 male (15.4 × 12.9 mm) ( NMCR 40102 ) Samar province, San Jorge municipality, Barangay Matalud, Can Gortio Cave , coll. P. Marcel, 20 March 1991 . Other material: 1 male (16.8 × 14.7 mm) ( MZUF 3927 ), Samar province, San Jorge municipality, Barangay Matalud, “ SNAZ 1 ” Cave (1 km from the local National School of Agriculture and Zootechnics), coll. C. Ferron, 26 May 1993 .

Comparative material. The specimens were compared with the descriptions of Sundathelphusa waray Husana, Naruse & Kase, 2009 and S. lobo Husana, Naruse & Kase, 2009 , as well as with the direct observation of the specimens of S. philippina (von Martens, 1868) deposited in the Museum für Naturkunde, Berlin ( ZMB), a Sundathelphusa species collected in Samar Island. These last specimens are presently catalogued as S. grapsoides , possibly following Balss (1937) (O. Coleman pers. comm.). Sundathelphusa philippina were collected in Samar in the following localities: Calbiga river and Loquilocum (= Ulut) river ( Bott, 1970). As the ZMB specimens were presently identified as S. grapsoides (H. Milne Edwards, 1853) , the original descriptions of this latter species were also carefully compared, following A. Milne Edwards (1869) and Rathbun (1904).

Description. Carapace ( Fig. 1A ) subquadrate, broader than long (width-to-length ratio ca. 1.1) quite flat; dorsal surface with distinct rugosity in frontal, hepatic regions; branchial region rugose, striated; regions poorly defined, cervical, gastric grooves shallow; epigastric cristae low but distinct, continuous with postorbital cristae; postorbital cristae low but distinct, gently curving toward anterior, converging toward and connecting epibranchial teeth; frontal margin slightly convex; anterolateral margins slightly convex, granular; external orbital angle not very broad; single epibranchial tooth acutely triangular, developed, anteriorly directed, separated from exorbital tooth by V-shaped notch; posterolateral margins slightly concave before converging towards posterior carapace margin; supraorbital margin smooth, parallel with frontal margin; infraorbital margins granular, complete, congruent with anterolateral margin; suborbital region rugose, extending to sub-branchial region. Antennules slender. Eyes well-developed, cornea pigmented.

Epistome narrow ( Fig. 1C ), posterior margin with one lateral cleft, median part sub-triangular, margin smooth. Third maxilliped ( Figs. 1B , 2A ) with slender, sinuous exopod, narrower than ischium, flagellum well developed; merus broad, antero-external margin rounded.

Male thoracic sternum ( Fig. 1B ) broad and generally smooth, with scattered granularities, lateral margins setose; sternites 1–4 fused, with traces of sutures between 3–4 sternites; sterno-abdominal cavity deep; press button on sternite 5, near to the suture between sternites 4 and 5.

Male chelae ( Fig. 1A ) distinctly unequal, relatively long, surface punctuated, with scattered rugosities, fingers shorter than palm; distal region of fingers with pointed, chitinous tooth; margin of merus irregularly granular. Carpus rounded, rugose, inner distal angle with well-developed tooth and with 1 or 2 smaller teeth in inner margin.

Ambulatory legs ( Fig. 1A ) sub-triangular in cross section; second, third ambulatory legs longest; anterior dorsal margin of merus (M) smooth; propodi (P) with spines, all dactyli (D) bearing spines; 3M long (length to width ratio 3.3), 3P long (length to width ratio 2.3), 3D long (length to width ratio 6.4); 4M short (length to width ratio 2.9), 4P long (length to width ratio 2), 4D relatively short (length to width ratio 3.8).

Male abdomen ( Fig. 2B ) T-shaped; lateral margins covered with short setae; Telson slightly shorter than somite 6, narrow, with lateral margins converging to rounded distal margin.

G1 ( Fig. 2D, E ) relatively stout, basal part swollen, terminally curved, subterminal segment straight with outer margin distinctly concave; proximal part evenly cylindrical, terminal part occupying about 0.2 times total length, nearly straight, conical, with fairly fluted tip. G2 ( Fig. 2C ) relatively long, slightly longer than G1, distal segment long, sinuous, about 0.5 times length of basal segment.

No females were collected, thus it is not possible to give any detail of female morphology.

Etymology. From the composition of spelaeo (Latin: spēlaeum, i) cavern and phila (Latin: -philus, -phila) lover, as it has been collected in a cave.

Remarks. At present, only three species of Sundathelphusa are known for Samar: S. philippina , S. lobo and S. waray .

However S. spelaeophila clearly differs from S. philippina in: (a) the subquadrate shape of the carapace (versus subexagonal, inflated and broader in S. philippina ); (b) poorly defined regions in the carapace (versus well defined regions in S. philippina ); and (c) G1 subterminal segment almost straight with outer margin distinctly concave (versus curved with outer margin convex in S. philippina ).

The other two species, described from caves, S. waray and S. lobo , are both regarded as obligate cave inhabitants by Husana et al. (2009). Sundathelphusa spelaeophila sp. nov. can be separated from these two species by the absence of evident troglobitic traits (e.g., reduced cornea pigment; absence of body pigment; length of legs and spines, see Husana et al., 2009) clearly present in S. waray and S. lobo .

Sundathelphusa spelaeophila sp. nov. can apparently resemble S. grapsoides (H Milne Edwards, 1853) . Even if this species is reported from Luzon (Pampanga and Bulacan; Mendoza & Naruse, 2010), an island quite distant from Samar ( Ng & Sket, 1996; Ng, 2010), it also shows remarkable morphological differences. Sundathelphusa spelaeophila differs from S. grapsoides descriptions reported in A. Milne Edwards (1869) and Rathbun (1904) by: (a) the subquadrate shape of the carapace (versus rounded shape of the carapace in S. grapsoides ); (b) the anterior side of the merus of the ambulatory legs smooth (versus numerous teeth in the anterior side of the merus of the ambulatory legs in S. grapsoides ); and (c) poorly defined regions of the carapace (versus well defined regions of the carapace in S. grapsoides ).

Figures

Fig. 1. Sundathelphusa spelaeophila n. sp., holotype, male (15.9 × 14.1 mm) (MZUF 3920). A, dorsal view (Scale bar = 10 mm); B, ventral view; C, anterior view.

Fig. 2. Sundathelphusa spelaeophila n. sp., holotype, male (15.9 × 14.1 mm) (MZUF 3920): A, right third maxilliped; B, abdomen; C, right G2, respectively ventral and dorsal view; D, right G1, respectively ventral and dorsal view; E, tip of right G1, respectively ventral and dorsal view. Scale bars = 1.0 mm.