Chiromantes garfunkel, Davie, Peter J. F. & Ng, Peter K. L., 2013

Davie, Peter J. F. & Ng, Peter K. L., 2013, A review of Chiromantes obtusifrons (Dana, 1851) (Decapoda: Brachyura: Sesarmidae), with descriptions of four new sibling-species from Christmas Island (Indian Ocean), Guam and Taiwan, Zootaxa 3609 (1), pp. 1-25 : 7-14

publication ID	https://doi.org/ 10.11646/zootaxa.3609.1.1
publication LSID	lsid:zoobank.org:pub:0C5E3F32-FB0B-4AF6-AD4F-9D96A1BA670B
DOI	https://doi.org/10.5281/zenodo.5618386
persistent identifier	https://treatment.plazi.org/id/CF079C1B-FF99-FFCA-FF5E-2E9292E3F996
treatment provided by	Plazi
scientific name	Chiromantes garfunkel
status	sp. nov.

Treatment

Chiromantes garfunkel View in CoL sp. nov.

( Figs 2 View FIGURE 2 , 4 View FIGURE 4 E, 5F, 6F, 7F, 8D, 9F, 10B, 12)

Sesarma (Holometopus) obtusifrons – Balss 1934: 229.

Sesarma obtusifrons —Gibson-Hill 1947: 44.—Tweedie 1947: 33.—George 1978: 13 (unnumbered pages).—Hicks et al. 1984: 22, 65 including colour picture.

Chiromantes obtusifrons —Davie 2002: 221.

Material Examined. HOLOTYPE: QM-W29172, male (17.0×13.0 mm), Greta Beach, Christmas Island, H.H. Tan, 0 8.12.2007. PARATYPES: ZRC 2012.0776, female (13.3×12.0 mm), station CI-33, Greta Beach, 10°30.127'S, 105°40.475'E, 27.03.2011.—ZRC 2012.0777, male (13.9× 10.6 mm), station CI-12, Greta Beach, 10°30.127'S, 105°40.475'E, limestone cliff, sandy beach, limestone bedrock, 24.01.2010.—ZRC 2012.0778, 4 males (13.5×10.2, 15.2×11.6, 18.2×14.7, 17.9×14.0 mm), 4 females (13.0×9.6, 14.3×10.8, 14.7×11.2, 17.5× 13.6 mm), station CI-06, The Grotto, Waterfall Road, 10°25.386'S, 105°42.127'E, weathered cave, tidal sump, 23.01.2010.—ZRC 2012.0779, 2 males (10.8×9.8, 14.5× 13.2 mm), station CI-07, Waterfall Bay, Christmas Island Resort, 10°27.54'S, 105°42.30'E, freshwater stream, sandy beach, limestone base rock, 23.01.2010.—ZRC 2012.0780, female (12.1× 9.1 mm), station CI-04, Merrial Beach, 10°28.455'S, 105°33.551'E, sandy beach, beach forest, limestone base rock, 20.03.2011.—ZRC 2012.0781, male (13.5× 10.2 mm), station CI-09, Ethel Beach, 10°27.805'S, 105°42.443'E, sandy beach, beach forest, limestone base rock, 21.03.2011.—ZRC 2012.0782, female (11.1× 8.3 mm), station CI-01, Flying Fish Cove, 10°25.815'S, 105°40.180'E, rocky, gravel beach, 22.01.2010.—ZRC 2012.0783, 1 ovig. female (11.4× 8.6 mm), station CI-01, Flying Fish Cove, 10°25.815'S, 105°40.180'E, rocky, gravel beach, 22.01.2010.—ZRC 2012.0784, male (14.0× 10.8 mm), Flying Fish Cove, 10°25.815'S, 105°40.180'E, rocky, gravel beach, 22.01.2010.—ZRC 2012.0785, female (10.8× 8.2 mm), station CI- 0 2, Lily Beach, 10°28.011'S, 105°42.688'E, sandy beach, beach forest, limestone base rock, 22.01.2010.—ZRC 2012.0786, female (11.6× 8.6 mm), station CI-02, Lily Beach, 10°28.011'S, 105°42.688'E, sandy beach, beach forest, limestone base rock, 22.01.2010.—QM-W29173, male (18.2× 13.8 mm), 3 females (12.8×9.8, 16.5×12.7, 16.6× 12.7 mm), 31.03.2011, The Blowholes, 10°30.861'S, 105°37.358' E, under limestone rocks adjacent vegetation at back of limestone terrace, P. Davie.—ZRC 1965.7.29.153, male (13.7× 10.4 mm), 1932, no specific location.—ZRC 1965.7.29.154-163, 2 males (larger 11.5× 8.8 mm), 7 females (largest 20.4× 16.2 mm), M.W.F. Tweedie, shore terrace along east and north coasts, and Isabel Beach, 0 2.03.1932. All localities Christmas I.

Diagnosis. Carapace transversely subovate, c. 1.3 times broader than long; dorsal carapace, lateral branchial regions prominently swollen; exorbital tooth at widest point only projecting slightly more than exorbital tooth; front c. 0.6 times carapace width, margin broadly convex in dorsal view, appearing smooth but microscopically granular, with pair of weak lateral swellings behind margin; supraorbital margin entire, straight, obliquely sloping posteriorly; outer surface of cheliped carpus moderately granular; walking legs relatively short; P4 merus c. 2.3 times longer than wide; P5 merus relatively narrower than P4 merus, c. 2.6 times longer; P4 propodus c. 2.8 times longer than wide; P5 propodus c. 2.7 times longer; male abdomen ( Fig. 12 View FIGURE 12 A) moderately broad; somite 6 with lateral margins diverging, slightly concave over distal half, more subparallel over proximal half; somite 3 width 3.0 times basal width of telson; G1 ( Fig. 12 View FIGURE 12 B–E) relatively slender, weakly tapering to prominent subdistal shoulder; terminal process long, with slender narrow apex, dorsal margin slightly sinuous.

Description. Carapace transversely subovate, c. 1.3 (range 1.26–1.35) times broader than long; surface bare, lacking setal tufts; covered with fine, but distinct low granules becoming arranged into short striae posteriorly; mesogastric regions well defined; lateral carapace surface generally without obvious discrete oblique striae, except for strong, concave epibranchial sulcus beginning just behind exorbital tooth. Dorsal carapace, lateral branchial regions relatively weakly convex, not prominently swollen ( Fig. 10 View FIGURE 10 A, B). Exorbital tooth triangular, pointed, outer margin long, slightly convex, at widest point only projecting slightly more than exorbital tooth; margin constricted behind, but no trace of second anterolateral tooth. Postfrontal lobes strongly demarcated, separated by broad grooves, median lobes similar in width to lateral lobes. Front c. 0.6 times carapace width (0.63 in holotype), markedly deflexed, margin broadly convex in dorsal view; laterally triangular, bluntly pointed; frontal margin emarginated, minutely granular ( Fig. 8 View FIGURE 8 D); surface somewhat concave behind frontal margin, but with pair of weak lateral swellings. Supraorbital margin entire, straight, obliquely sloping posteriorly at about 45° angle; secondary rim sloping obliquely inwards, downwards to form smooth, broadly triangular, deflexed plate behind ocular peduncle. Eye not extending beyond exorbital tooth. Frontal plate protruding as shelf; medial septum broad, largely covering anterior half of anterior half of epistome; antennae, antennules much reduced in size, lodged under overhanging front; basal antennular segment not much swollen; antennal, antennular basal segments adjacent, not separated by septum. Antennal flagellum conspicuously short, entering orbit.

Third maxilliped ischium, merus subequal in length; ischium with shallow longitudinal, curved, median sulcus. Merus, ischium inner margins with long setae, ischium proximal outer margin, base of exopod with dense setae; merus outer margin with short scattered setae only. Exopod slender, hidden behind ishium, merus except near base, tip reaching half length of outer margin of merus, flagellum long, slender.

Chelipeds subequal, robust. Merus trihedral; posterior border broadly convex, emarginated, minutely granular, without indication of subdistal spine or lobe; inner anterior border minutely granular, broadly triangular; outer surface broadly convex, with fine transverse striae but appearing almost smooth. Carpus subquadrilateral, inner angle moderately produced, apically granular; outer margin, dorsal surface moderately granular. Palm dorsal surface slightly striated along superior margin, with scattering of moderate sized granules, otherwise smooth, punctate. Palm outer surface broadly rounded, smooth; no indication of subventral longitudinal ridge. Inner face of palm in males smooth except for curved projecting crest of large tubercles behind gape ( Fig. 6 View FIGURE 6 F), but prominence variable. Cutting margin of fixed finger with 3 or 4 blunt teeth ( Fig. 5 View FIGURE 5 F), proximal 3 similar in size, distalmost larger, rounded, conical, placed medially; dactylus with 2 proximal teeth, distalmost large, third much smaller blunt tooth slightly distal of medial tooth of ventral finger; teeth on both fingers can vary in prominence. Dorsal surface of dactylus smooth. Fingers with chitinous tips; adult males with narrow but distinct gape when fingers closed.

Walking legs relatively short, broad, flattened; second, third pairs sub-equal, longer than other walking legs. Without setae except for scattering of short dark bristles on dactyli, ventral face of propodi. Dorsal margins of meri with blunt subdistal shoulder, otherwise unarmed; outer surfaces of meri with minutely granular transverse striae. P4 merus c. 2.3 times longer than wide; P5 merus relatively narrower than P4 merus, c. 2.6 times longer. Carpi with 2 accessory carinae on outer surface but not strongly marked. P4 propodus c.2.8 times longer than wide; P5 propodus c. 2.7 times. Dactyli 0.8 times length of propodi, slightly recurved, terminating in acute chitinous tip.

Thoracic sternites ( Fig. 9 View FIGURE 9 F) smooth, mostly bare of setae except for few scattered bristles; abdominal cavity reaching to thick transverse setal fringe at junction of sternites 3, 4. Male abdomen ( Fig. 12 View FIGURE 12 A) moderately broad; telson broadly rounded apically, 1.1 times longer than wide, slightly longer than somite 6; somite 6 c. 1.8 times wider than long, lateral margins divergent, slightly concave over distal half, but more subparallel over proximal half; somites 3–5 trapezoidal, lateral margins of somites 4, 5 relatively straight, lateral margins of somite 3 convex; somite 3 width 3.0 times basal width of telson; somites 1, 2 transversely, longitudinally narrow.

G1 ( Fig. 12 View FIGURE 12 B–E) relatively slender, straight, weakly tapering to prominent subdistal shoulder; distally slender, strongly bent to 45° angle; terminal process long, with slender narrow apex, dorsal margin slightly sinuous. G2 short, as for the genus.

Females. Chelipeds slightly smaller, less robust, lacking raised granular row on inner face of chela. Vulval morphology without clear species-specific characters.

Colour in life. Colour photographs taken from fresh specimens are shown in Fig. 2 View FIGURE 2 . Carapace and legs of adults rich, dark purple to maroon; without prominent speckling or splotching. Legs uniform in colour, without transverse banding. Chelipeds relatively uniform in colour, not clearly darker dorsally; off-white to white porcelain in adults, markedly contrasting with purple carapace. Ocular peduncles same as carapace in colour; corneas bright yellow ( Fig. 2 View FIGURE 2 A–D). Female specimens from more exposed supralittoral areas behind beaches can be paler in coloration, with the carapace and legs beige with streaks of purple and brown ( Fig. 2 View FIGURE 2 E, F). Their eyes, however, are still bright yellow.

Remarks. This species was first recorded from Christmas Island by Balss (1934) as Sesarma obtusifrons . It was subsequently listed by Gibson-Hill (1947a, b) and Tweedie (1947) who reported on comparisons with specimens from the Hawaiian Islands made by F.A. Chace (in litt. to M. Tweedie). Chace noted (Tweedie, 1947: 34) that the Christmas I. specimens had more slender legs but felt that it was within the possible range of variation. It was pictured by Hicks et al. (1984: 65), who gave a short account and gave it the name “Yellow-eyed Crab” ( Sesarma obtusifrons ) because “Bright yellow eyes peering from a pock-mark in the seacliff are all you normally see of this shy little crab”. They further commented: “Yellow-eyed crabs live high on the seacliff, beyond tidal or salt spray influences, and have been recorded all around the coast.”

Tweedie (1947) considered the record of Sesarma obtusifrons by De Man (1895, 1898) from Atjeh, Sumatera, Indonesia as being conspecific with his Christmas I. samples. We disagree and consider that the identity of these specimens must remain unresolved at this time. From De Man’s figure (1898: pl. 29, fig. 31) the abdomen appears significantly narrower than in C. garfunkel and the legs are relatively shorter, both characters that are useful in separating other species in the group. Furthermore, the live colouration was well described by De Man and this does not agree with the colour of the Christmas I. species. De Man (1895: 161–165) described the colour as “The surface of the carapace has an olive-green base color [purple in C. garfunkel ] and transmits some symmetrically arranged dark brown patches of irregular shape. The lower frontal border, the orbital margins, and the lateral margins are yellowish, as are the depressions of the hepatic regions immediately behind the external orbital angle. The claws are yellowish, turning reddish-yellow dorsally, the legs are brownish in color with purple transverse bands.The numerous features that distinguish this species from its closest congeners are given in Table 1 View TABLE 1 .

Etymology. Named for Art Garfunkel , who sang “Bright Eyes” for the soundtrack of the 1978 animated film Watership Down. Like the rabbit to which the song alludes, the new crab species also lives in holes, and is remarkable for its brightly shining eyes. The name is used as a noun in apposition.

Distribution. Only known from Christmas Island, eastern Indian Ocean.

Ecology. Gibson-Hill (1947b: 44) noted that: “Yet another species, Sesarma obtusifrons , is fairly plentiful in the pock-marks and crevices at the top of the sea cliff. It is particularly common in Flying Fish Cove and behind Greta and West White Beaches. It also occurs up on the shore terrace proper, at the base of the inland cliff, and during the rainy season can occasionally be found in the open. Females with spawn (a crab with a carapace width of 18 mm carrying about 5500 eggs) are most frequent from January to April. The spawn is taken to the sea and deposited, at low tide, on the edges of the rock pools on the uncovered portions of the fringing reef.” George (1978) largely repeated the earlier notes made by Gibson-Hill (1947a, b). Hicks et al. (1984: 65) stated: “Yellow-eyed crabs live high on the seacliff, beyond tidal or salt spray influences, and have been recorded all around the coast.” Our personal observations agree entirely with these earlier authors.