Geosesarma tagbanua, Manuel-Santos & Ng & Freitag, 2016

Manuel-Santos, Marivene, Ng, Peter K. L. & Freitag, Hendrik, 2016, Two new species of Geosesarma De Man, 1892 (Crustacea: Brachyura: Sesarmidae) from Palawan, the Philippines, Raffles Bulletin of Zoology 64, pp. 335-342 : 340-341

publication ID	https://doi.org/ 10.5281/zenodo.5355486
publication LSID	lsid:zoobank.org:pub:C2FD963A-4DB8-43C9-B940-DA1F7FD333F1
persistent identifier	https://treatment.plazi.org/id/5C112C7B-902D-FFDA-9BBF-F831EA1C9CD8
treatment provided by	Valdenar
scientific name	Geosesarma tagbanua
status	sp. nov.

Treatment

Geosesarma tagbanua View in CoL , new species

( Figs. 2A–D View Fig , 3A–C, 4G–L View Fig )

Material examined. Holotype: male (21.8 × 21.8 mm) (NMCR-40107), Quezon, Lipuun Point, Tabon Caves , c. 4

km NNW Quezon town, c. 9°16’N 117°59’E, coll. J. Orcullo, March 2003. Paratypes: 3 males (largest 20.0 × 20.1 mm) ( ZRC, SMTD-S172 ), same data as holotype ; 1 male (21.2 × 21.7 mm) (NMCR-25052), Narra, Tuas, Estrella Creek , ca 370 m asl, 9°19’N, 118°20’E, coll. M. R. Manuel-Santos, 24 May 1990. All locations in Palawan Island, Philippines GoogleMaps .

Diagnosis. Carapace squarish; dorsal surfaces flat, rough, frontal margin strongly deflexed at 90° from horizontal view; postfrontal crest divided into 4 dentiform granulated lobes. Outer surface of chela densely covered with low rounded granules; dorsal margin with incomplete granular ridge. Ambulatory legs relatively longer, fourth merus 0.9 times as long as carapace width. Male abdominal somite 6 slightly shorter than telson; male telson relatively narrower, 1.2 times wider than long. G1 long, slender; shaft rather abruptly tapering subapically, forming angle, distal chitinous part bent laterad at 45°, moderately slender, long, broad, relatively straight except for curved apex.

Description of holotype male. Carapace ( Fig. 2A View Fig ) squarish, about as long as wide; lateral margins almost subparallel or slightly diverging towards posterior carapace margin; dorsal surfaces approximately flat, not convex, rough, with low granules; gastric and branchial regions swollen; hepatic region depressed; grooves deep, regions well defined. Postfrontal crest overall straight, with 4 dentiform postfrontal lobes, reaching or extending slightly beyond frontal margin in dorsal view; anterior margins granulate; median cleft connected with mediogastric groove; protogastric protuberances behind relatively inconspicuous lateral postfrontal lobes; front prominently deflexed from dorsal carapace at right angles; ventral front margin sinuous; sublateral areas distinctly lobiform. Orbital margin angularly bent abruptly, not sinuous. External orbital tooth broadly triangular, directed antero-laterad, entirely slightly upward directed; tip sharp, pointed; first anterolateral tooth smaller, broadly triangular, tip acute, pointing antero-laterad; second anterolateral tooth very low or inconspicuous; lateral margins finely granular, slightly cristate. Posterolateral regions with fine oblique striae.

Third maxillipeds ( Fig. 2B View Fig ) as in previous species.

Thoracic sternites ( Fig. 2B View Fig ) as in previous species. Abdomen ( Fig. 2B View Fig ) with telson ca. 1.15–1.25 wider than long, lateral margins gently convex on distal part, almost straight proximally, tip rounded; somite 6 slightly shorter than telson, distal part of lateral margin convex, proximal part almost straight; somites 3–5 increasingly trapezoidal; somites 1 and 2 transversely narrow.

Male chelipeds ( Fig. 2A, C, D View Fig ) as in previous species.

Ambulatory legs ( Fig. 2A View Fig ) slender, very long; fourth ambulatory merus about 0.9 times as long as carapace width, lateral margins of meri subparallel at least from basal 0.3 to 0.8. Otherwise similar to previous species.

G1 ( Fig. 4G–I View Fig ) long, slender, straight, reaching distal end of abdominal somite 6; subdistal inner margin with long setae that do not overreach tip; basal part rounded, prominent ( Fig. 4H View Fig ); shaft rather abruptly tapering subapically near distal chitinous part, apically rather abruptly angled lateral at 45° in ventral view ( Fig. 4G View Fig ); distal part moderately slender, moderately long, slightly bent dorsad in lateral view ( Fig. 4H View Fig ), overall rather straight, but apex distinctly curved. G2 ( Fig. 4J View Fig ) moderately short; base subtriangular; distal part slender, outer margin gently curved.

Colour in life. Not known.

Etymology. Named after the Tagbanua, an indigenous tribe in Palawan, who like the Bataks, get their sustenance from the forests. The name is used as a noun in apposition.

Distribution. Only known from two sites in the Municipalities of Narra and Quezon of the Province of Palawan, the Philippines.

Ecological notes. Specimens were collected in a limestone cave and at a montane forest. One specimen (NMCR-25052) was collected across a creek at ca. 370 m elevation at Mt. Victoria. The site was surrounded by huge boulders of algae-covered rocks where dipterocarps, bamboos and thorny rattans dominated. The specimen was found there by the first author among the fallen barks of “almaciga” ( Agathis loranthifolia ) near the creek banks.

Remarks. The paratype male specimen of G. tagbanua , new species, from Narra (NMCR-25052) ( Figs. 3A–C, 4K, L View Fig ) differs slightly from the remaining type material in its carapace shape, which appears to be somewhat rounder and is 1.02 times longer than broad. The carapaces of the remaining specimens are distinctly more squarish and almost exactly as wide as long. Furthermore, its dorsal surface is slightly more concave, the external orbital teeth are more acute and pronounced ( Fig. 3A right side; cf. Fig. 2C View Fig ), and the dactylar finger of the chela is slightly stouter and lacks the dorsal row of granules ( Fig. 3C; cf. Fig. 2D View Fig ). The G1 of this specimen is also not as strongly chitinised as the other specimens. These observations suggest this specimen had recently moulted. However, all the other key diagnostic characters, notably that of the G1 and G2 ( Fig. 4L, K View Fig ; cf. Fig. 4G, J View Fig ) is consistent with the other specimens and we regard them all as conspecific for now.