Orcovita tabiacoud, Stasolla & Innocenti, 2014

Stasolla, Gianluca & Innocenti, Gianna, 2014, A new species of cavernicolous crab from Coron Island, Palawan, the Philippines (Decapoda: Brachyura: Varunidae), Raffles Bulletin Of Zoology 62, pp. 591-599 : 596-597

Orcovita tabiacoud , new species

( Figs. 5–7 )

Material examined. Holotype – male (26.2 × 18.9 mm) ( MZUF 4269 ), Coron Island , Pukaway Cave, coll. R. Berti & S. Meggiorini, 15 March 1991.

Description. Carapace ( Figs. 5A , 7A ) subhexagonal, distinctly broader than long (width/length ratio ca. 1.3), dorsal surface finely punctate, regions poorly defined; cervical grooves poorly distinct; gastric grooves deep; epigastric, postorbital cristae absent; anterolateral margin lined with small, feeble granules; external orbital angle very broad, with one broad, epibranchial tooth ( Fig. 7C ), separated from external orbital angle by a small cleft; posterolateral margins concave before converging towards the posterior carapace margin; supraorbital margin granular, gently sinuous, parallel to sub-parallel with frontal margin; frontal margin sinuous, slightly concave; infraorbital margins granular, incomplete, not congruent with anterolateral margin; distinct row of rounded granules present just below infraorbital margin on suborbital region, extending to sub-branchial region. Antennules slender. Eyes developed, cornea pigmented.

of merus smooth, inner surface of superior margin granular. Carpus rounded, smooth, inner distal angle with very low, obtuse tooth. Chelipeds relatively long, robust, surface of articles smooth without any trace of longitudinal sulcus; tips of fingers corneous, spoon-like, lacking setae.

Ambulatory legs ( Fig. 7I ) sub-circular in cross section, all articles but merus stout; second ambulatory leg longest; proximal surface finely granular. Anterior dorsal margin of merus with rounded subdistal tooth, sparse setae; outer surface of carpus with short setae, anterior and posterior margins of propodus with long and short setae, respectively; dactylus rectangular in cross section, with five rows of short and dense setae, tapering to slender, acute tip; posterior margin of the dactylus of the first four ambulatory legs with dense short setae interspersed with several long ones; 3M long, slender (length to width ratio 4.3), 3P long (length to width ratio 4.2), 3D long (length to width ratio 6.69); 4M short (length to width ratio 4), 4P long (length to width ratio 3), 4D long, slender (length to width ratio 5.4) (see Table 1).

Male abdomen ( Fig. 7B ) triangular; lateral margins covered with short dense setae with several long, pigmented setae interspersed; telson with lateral margins feebly convergent distally, distal margin rounded.

G1 ( Fig. 7G ) strong, gently curving outwards, reaching to or slightly beyond anterior margin of sternite 5; terminal lobe densely setose, sub-terminal lobe absent. G2 ( Fig. 7H ) short, small.

Epistome ( Fig. 6 ) narrow, posterior margin with 2 lateral clefts, median part sub-triangular, margin smooth. Third maxilliped ( Fig. 7F ) with broad, stout exopod, broader than ischium, flagellum well developed; merus broad, anteroexternal angle auriculiform.

Male thoracic sternum ( Fig. 5B ) with lateral margins of first two thoracic sternites smooth; suture between sternites 2, 3 slightly concave with sparse setae; lateral margins of sternites 3, 4 sinuous, with deep, broad notch; median longitudinal groove (median line) along sternites 5, 6, 7, 8 narrow.

Male chelae ( Fig. 7D, E ) swollen, subequal, fingers shorter than palm; proximal region of cutting edges of fingers with very small pulvinus. Inner, outer surfaces near inferior margin

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Colour. Live colour not known. Preserved specimen uniformly dark cream.

Etymology. From the name of the Tagbanua god of the underworld, Tabiacoud, as an allusion to the type locality of this crab.

Remarks. Three species of Orcovita have been previously reported from the Philippines, O. fictilia Ng, Guinot & Iliffe, 1996 from Panglao (Bohol), and O. angulata and O. holthuisi from Coron Island (Palawan).

Orcovita tabiacoud , new species, is perhaps most similar to O. gracilipes Ng, Guinot & Iliffe, 1996 in the shape and proportions of its carapace (see Ng et al., 1996), but still O. tabiacoud has a more marked subexagonal shape.

Orcovita tabiacoud is markedly different from O. fictilia due to (a) the smooth inner margin of the male cheliped carpus (vs. granular in O. fictilia as reported by Ng et al., 1996); (b) the male cheliped is without setae on the pulvinus (vs. cheliped with short, soft setae on the pulvinus in O. fictilia ); (c) the relatively stout ambulatory legs (vs. more slender ambulatory legs in O. fictilia , for proportions, see Table 1).

Orcovita tabiacoud is also clearly different from O. angulata , in (a) having a slightly broader carapace, with a width-tolength ratio of ca. 1.4 (vs. broader carapace, with a ratio of 1.3 in O. angulata ); (b) presence of a rounded junction of the antero- and posterolateral margins of the carapace (vs. presence of a distinct angular antero-posterolateral junction in O. angulata ); (c) the absence of low, distinct epigastric cristae (vs. weak and low epigastric cristae in O. angulata ); (d) the inner margin of the male cheliped carpus is smooth (vs. serrated in O. angulata ); (e) the male cheliped lacks setae (vs. cheliped with short, dense setae on cheliped tips in O. angulata ); (f) the relatively stout ambulatory legs (vs. more longer and slender ambulatory legs in O. angulata ).

The differences with O. holthuisi are (a) a broader carapace with a width to length ratio of ca. 1.4 (vs. narrow carapace with a ratio of 1.2 in O. holthuisi ); (b) anterolateral margin with two broad teeth including the exorbital angle (vs. three acute and strong teeth including the exorbital angle in O. holthuisi ); (c) absence of epigastric cristae (vs. low and distinct epigastric cristae in O. holthuisi ); (d) male cheliped without setae (vs. cheliped with long dense setae on the pulvinus in O. holthuisi ); (e) relatively longer ambulatory legs (vs. relatively shorter and stouter ambulatory legs in O. holthuisi ).

Davie & Ng (2012), who provided a key of the Orcovita species, recognised two separate species-groups of Orcovita that may represent distinct lineages, due to a probable ancient phylogenetic split. Orcovita tabiacoud seems to be assigned to Group II for the single epibranchial tooth, relatively long and slender legs, and lack of a prominent patch of setae on the chelae. Thus, in Pukaway cave, for the first time, there is the occurrence of one species belonging to Group I ( O. holthuisi ) and two ( O. angulata and O. tabiacoud ) ascribed to Group II.

Figures

Fig. 5. Orcovita tabiacoud n. sp., holotype, male (26.2 × 18.9 mm)

Fig. 6. Orcovita tabiacoud n. sp., holotype, male (26.2 × 18.9 mm)

Fig. 7. Orcovita tabiacoud n. sp., holotype, male (26.2 × 18.9 mm) (MZUF 4269); A, carapace; B, abdomen; C, epibranchial region; D, dorsal view of left cheliped; E, dorsal view of carpus of cheliped; F, third maxilliped; G, different views of G1; H, different views of G2;