Garthiella sikatuna, Mendoza & Manuel-Santos, 2012

Mendoza, Jose Christopher E. & Manuel-Santos, Marivene R., 2012, Revision of Garthiella Titgen, 1986 (Crustacea: Decapoda: Brachyura: Xanthidae), with description of a new subfamily and a new species from the central Philippines, Zootaxa 3446, pp. 32-48 : 40-46

Garthiella sikatuna sp. nov.

Figs. 4, 5, 6C, D, 7 E-H, 8B

Material examined. Holotype, ♂, 10.5 × 6.4 mm ( NMCR 39036 ), stn B41, 17– 19 m, floor of large cave, 9°30.9´N 123°40.8´E, Balicasag Is., Bohol, coll. PANGLAO 2004, 4 July 2004.

Paratypes: 1 ♂, 9.9 × 6.1 mm ( ZRC 2012.0163 ), same as holotype ; 1 ♂, 9.8 × 6.1 mm ( NMCR 39037 ), stn B10, 3– 14 m, reef wall with small caves, 9°36.5´N 123°45.6´E, Momo Beach, Panglao Is., Bohol, coll. PANGLAO 2004, 10 June 2004 ; 1 ♀ (with bopyrid), 11.3 × 6.8 mm ( ZRC 2010.0142 ) stn B37, 19– 20 m, floor of cave, with corals & sponges, 9°30.9´N 123°40.8´E, Balicasag Is., Bohol, coll. PANGLAO 2004, 2 July 2004 ; 1 ♂, 7.8 × 4.9 mm (MNHN-IU-2012-1), stn B13, 3– 5 m, coral rubble, 9°37.1´N 123°52.6´E, Baclayon Takot, Panglao Is., Bohol, coll. PANGLAO 2004, 15 June 2004 ; 1 ♂, 9.8 × 6.1 mm ( ZRC 2012.0164 ), stn B16, 20 m, coral rubble on sand & gravel, 9°37.6´N 123°47.3´E, Bingag, Panglao ls., Bohol coll. PANGLAO 2004, 17 June 2004 ; 1 ♀, 9.5 × 6.0 mm (MNHN-IU-2012-2), stn B36, 24 m, reef wall, 9°35.9´N 123°44.5´E, north of Doljo , Panglao Is., Bohol, coll. PANGLAO 2004, 1 July 2004 ; 1 ♀, 7.6 × 4.8 mm ( ZRC 2012.0165 ), stn R30, 15– 37 m, reef slope with black coral & gorgonians, 9°37.1´N 123°46.1´E, Napaling, Panglao Is., Bohol, coll. PANGLAO 2004, 8 June 2004 .

Diagnosis. Carapace transversely subovate, width 1.6-1.7 times length; dorsal surface depressed, marked by prominent transverse rows of small granules anteriorly; regions moderately defined. Front nearly level with orbits, bilobed. Anterolateral margin convex with 4 teeth, mostly curviform, more prominent. Chelipeds long, slender, coarsely granular; fingers long, tips pointed, incurved, crossing. Ambulatory legs long, slender; anterior margins of meri, carpi, and anterior, posterior margins of propodi spinulose. Distal tip of G1 bilobed, mesial lobe extended, lateral lobe bent, crossing mesial lobe; with more subterminal setae.

Description. Carapace transversely subhexagonal to subovate, width about 1.6–1.7 times length; dorsal surface depressed, sparsely setose, with transverse rows of truncatiform granules on anterior, lateral regions, central, posterior regions finely granular; regions well defined, separated by wide, smooth, glabrous grooves; 1F, 2F indistinct, 1M fused with inner branch of 2M, 2M partially divided longitudinally, 3M entire, well defined, 4M indistinct, 1L, 3L, 4L indistinct, 2L, 5L, 6L entire, well defined; 1P, 2P flattened, indistinct, 1R-3R indistinct. Front bilobed, deflexed, granular; frontal width about 0.3 times carapace width; lobes separated by deep, U-shaped, median sinus; each lobe with slightly convex anterior margin, with lateral angles slightly produced. Anterolateral margin slightly convex, slightly shorter than posterolateral margin, with 4 denticulate teeth posterior to exorbital angle; first tooth small, blunt, second to fourth teeth larger, curved at tips, denticulate on external margins. Posterolateral margin granular, nearly straight. Posterior margin finely granular, slightly concave at central area. Orbits rounded; superior, inferior margins cristate, spinulose; supraorbital region clearly demarcated by wide, smooth groove; eyes large, corneas well developed. Pterygostomial region similar to dorsal surface of carapace.

Antennular fossae large. Basal antennal article subrectangular, with small granules, inner angle touching ventral prolongation of front; outer angle prolonged partially into wide orbital hiatus, not closing hiatus to antennal flagellum. Pterygostome with small, narrow, accessory plate abutting against lateral margin of antennal basal segment. Anterior portion of epistome bordering antennules with round granules; posterior margin of epistome entire, with median projection. Endostomial ridges developed only on posterior region. Third maxillipeds granular, densely bristled medially, with scattered setae over external surface; merus subquadrate, anterior margin slightly concave, anterolateral angle produced; ischium subrectangular, with median longitudinal sulcus.

Thoracic sternum of male profusely covered with round granules. Sternites 1, 2 fused, separated from sternite 3 by clear suture; sternite 3 partially fused to sternite 4, sutures limited to extreme lateral regions only, replaced centrally by distinct, smooth, transverse groove; sternite 4 large, with short median line; sternites 5–8 well separated by sutures; sternite 8 partially visible externally between abdominal somite 2, coxa of P5;

sternoabdominal cavity moderately deep; press-button relatively large, positioned anteriorly, close to suture 4/5; median line continuing uninterrupted on sternite 4, absent on sternites 5, 6, present on sternites 7, 8.

Chelipeds subequal, densely covered with conical and round granules, sparsely setose. Merus relatively longer than that of preceding species, distal end noticeably exceeding carapace; carpus with small, curved tooth, several prominent conical granules on inner angle; palm slightly inflated, superior half covered with large conical granules, inferior half with smaller, round granules, internal surface similar. Fingers deeply grooved; conical granules extending almost to distal tips; teeth well developed; tips curved, pointed, crossing each other; entire length pigmented except at tips, pigment on fixed finger extending into palm.

Ambulatory legs moderately long, P3, P4 longest, slightly longer than maximum carapace width; surfaces granular, moderately setose, anterior margins of meri, carpi, propodi spinose; meri length about 0.3–0.4 times total leg length, anterior margins with prominent, regularly spaced spines, terminating distally with large spine, posterior margin with smaller spines, granules; carpi with two rows of spines on, near anterior margin; propodi longer than carpi, spinose on anterior, disto-posterior margins; dactyli straight, slender, slightly longer than propodi, with small granules, margins lined with spiniform setae mixed with longer plumose setae, distal tip terminating in long, curved, chitinous claw, subdistal calcareous teeth absent on flexor surface; dactylo-propodal locking mechanism absent.

Male abdomen relatively large, lateral margins concave; somites 1, 2, proximal region of somite 3 all granular, rest smooth; somites 3–5 immovably fused with traces of sutures visible; somite 6 subquadrate, wider than long, disto-lateral angles slightly produced; telson subtriangular, basal width greater than median length, tip level with sterno-coxal condyles of chelipeds.

G1 moderately long, slender, curved; distal third with rows of small spines along length; distal portion with several (at least 15) stiff, simple, subterminal setae; terminal end bilobate, mesial lobe narrow, extended, straight, lateral lobe wider, bent, crossing mesial lobe. G2 about one-third length of G1. Penis short, emerging from gonopore on coxa of P5 anterior to coxo-sternal condyle.

Morphology of female identical to that of male, except in sexual characters. Abdomen wide, oval, lateral margins convex, all somites freely articulated; somite 4 widest; telson large, subtriangular. Segmentation of thoracic sternum, condition of median line as in male. Vulvae on thoracic sternite 6, close to median axis and to suture 5/6; sternal vulvar cover originating from medial margin of vulvae, rounded, almost completely closing vulvae.

Etymology. This species is named after Sikatuna, a 16 th century Datu (Lord) of the island of Bohol; used as a noun in apposition.

Remarks. Garthiella sikatuna sp. nov. is easily distinguished from G. aberrans by the following morphological features: 1) the granulation of the carapace and chelipeds is generally less coarse, with the granules being smaller and rounder ( Figs. 4A, 6C, D) (larger and sharper granules in G. aberrans ; Figs. 1A, 2A, 6A, B); 2) the carapace appears depressed and flatter in anterior view ( Fig. 4B) (higher in G. aberrans ; Fig. 1B, 2B); 3) the teeth on the anterolateral margin of the carapace are more projecting and curved ( Fig. 4A) (less projecting and curved in G. aberrans ; Figs. 1A, 2A); 4) the lobes of the front have much reduced lateral teeth ( Fig. 5A) (more pronounced in G. aberrans ; Fig. 3A); 5) the anterior border of the merus of the mxp3 is less concave ( Fig. 5B) (pronouncedly concave in G. aberrans ; Fig. 3B); 6) the posterior margin of the epistome is entire ( Fig. 4B) (crenulate in G. aberrans ; Fig. 1B); 7) the chelipeds are relatively longer and more slender, with the distal end of the merus well exceeding the carapace in dorsal view ( Figs. 4A, 6C, D) (shorter and stouter in G. aberrans , with the distal end of merus barely exceeding the carapace from dorsal view; Figs. 2A, 6A, B); 8) the ambulatory legs are relatively longer, P5 total length/carapace length ratio = 1.66 ( Fig. 4A) (relatively shorter in G. aberrans , P5 total length/carapace length ratio = 1.46; Fig. 2A); 9) the distal portion of the G1 has more subterminal setae, at least 15 ( Fig. 7G, H) (less setae, about 5, in G. aberrans ; Fig. 7C, D); and 10) the lateral lobe at the tip of the G1 is bent and crossing the mesial lobe ( Fig. 7H) (lateral lobe folded back and directed toward the sternum and base of the G 1 in G. aberrans ; Fig. 7D).

The live colouration of G. sikatuna sp. nov. ( Fig. 8B) consists of an orange carapace with irregular brown and white splotches; eyestalks that are white with brown stripes, and the corneas dark green; the chelipeds similarly orange, with brown and white splotches as in the carapace, particularly the meri, carpi and palm; the fingers dark brown throughout their length; and the ambulatory legs banded brown and white.

Ecology and geographical distribution. The type specimens of Garthiella sikatuna sp. nov. were all collected from a small area in the Bohol Sea, encompassing the islands of Balicasag and Panglao , by the PANGLAO 2004 expedition, by the brushing of rocks and coral rubble by scuba divers as described in Bouchet et al. (2002). The specimens were collected from the floor of underwater caves, from reef walls or slopes, as well as from coral rubble, sand and/or gravel substrate, at depths of 3–37 m.