Borneosa aspera ( Ng & Stuebing, 1989 )

Ng, Peter K L & Grinang, Jongkar, 2022, Establishment of A New Bornean Genus of Gecarcinucidae (Crustacea: Brachyura), with Descriptions of Five New Species., Zoological studies 61 (13), pp. 1-35 : 7-8

publication ID	https://doi.org/ 10.6620/ZS.2022.61-13
DOI	https://doi.org/10.5281/zenodo.8055962
persistent identifier	https://treatment.plazi.org/id/CF2E433D-3C34-FFA4-FC25-FDA330A8FE9A
treatment provided by	Valdenar
scientific name	Borneosa aspera ( Ng & Stuebing, 1989 )
status

Treatment

Borneosa aspera ( Ng & Stuebing, 1989) View in CoL

( Figs. 1B, D View Fig , 4 View Fig , 5 View Fig , 19B View Fig , 20M–P View Fig , 23B View Fig )

Sundathelphusa aspera Ng & Stuebing, 1989: 14 View in CoL , figs. 1, 2; Ng and Yeo 2007: 12; Ng et al. 2008: 72; Cumberlidge et al. 2009: unpaginated appendix; Ng 2015: 497, figs. 4–6, 7I–K.

Material examined: Holotype male (42.6 × 32.8 mm) ( ZRC 1989.2143 View Materials ), clear, swift forest stream, Sungei Rabergan, tributary of Sungei Muaya, near Mendalong , 4°57'N 115°43'E, 750 m asl, Sipitang District , Sabah, Malaysia. GoogleMaps Others : 1 male (32.3 × 25.4 mm), 1 female (44.1 × 33.1 mm) ( ZRC 2014.845 View Materials ), Temburong, Amo , Batu Apoi Forest Reserve , Ulu Temburong National Park , Brunei, coll. Jangorun anak Eri , 7 August 2014; GoogleMaps 1 female (44.5 × 33.7 mm) ( ZRC 2013.746 View Materials ), Bukit Pagon, Temburong District, Brunei, 900 m asl, coll. S. Salam, 6 July 2012; GoogleMaps 2 females (29.3 × 23.0 mm, 19.7 × 15.6 mm) ( ZRC 2012.1225 View Materials ), in primary forest stream, in area near Sarawak border, Brunei, coll. H. Mohammod, October 2012. GoogleMaps

Diagnosis: Adult carapace transversely ovate, width to length ratio 1.27–1.30 ( Figs. 4A, B View Fig , 5F View Fig ); striae on lateral parts of carapace strong ( Figs. 4B View Fig , 5F View Fig ); branchial regions gently convex in frontal view ( Fig. 4C, F View Fig ); dorsal margin of frontal median triangle contiguous with lateral margins ( Fig. 4C–E View Fig ); exorbital tooth with outer margin almost entire ( Figs. 4B View Fig , 5F View Fig ); epibranchial tooth low, separated from rest of margin by shallow low cleft ( Figs. 4B View Fig , 5F View Fig ); median lobe of posterior margin of epistome obtusely triangular ( Fig. 4C–E View Fig ); ischium of third maxilliped subquadrate ( Fig. 5A View Fig ); fingers of adult male cheliped closing along entire cutting margins ( Fig. 5D, E View Fig ); P3 dactylus longer than P4 dactylus ( Fig. 5H, I View Fig ); male pleonal somite 6 rectangular, longer than broad ( Fig. 5C View Fig ); male sternopleonal cavity not prominently anterior, distance between tip of cavity and suture of thoracic sternites 2 and 3 subequal to length of thoracic sternite 2 ( Fig. 5B View Fig ); adult Gl subterminal segment very slender; terminal segment cylindrical, distal half almost straight, tip wide, truncate, 0.35–0.37 times length of subterminal segment, distal opening very wide, ovate ( Fig. 20M–O View Fig ); vulvae transversely subovate ( Fig. 23B View Fig ).

Colour: In life, the carapace and pereopods of the species are dark to dull brown, with the ventral and frontal surfaces light brown to yellow and pale yellow; the pleon being reddish-brown ( Fig. 24A–G View Fig ).

Remarks: Described on the basis of one large male by Ng and Stuebing (1989) from northern Sabah, the species was subsequently recorded and redescribed at length on the basis of a larger series of specimens from Brunei ( Ng 2015). Borneosa aspera is the most distinctive member of the genus as it reaches the largest sizes (a female, 44.5 × 33.7 mm, ZRC 2013.746) and males also have proportionately, the longest G1 terminal segment ( Fig. 20M–O View Fig ).

Biology: All the specimens were collected from primary highland rainforest streams.