Geothelphusa leeae, Shy, 2005

Shy, Jhy-Yun, 2005, A New Species Of Freshwater Crab Of The Genus Geothelphusa Stimpson, 1858 (Crustacea, Decapoda, Brachyura, Potamidae) From Taiwan, Raffles Bulletin of Zoology 53 (1), pp. 99-102 : 100-101

Geothelphusa leeae new species

( Figs. 2 , 3 )

Material examined. – Holotype - 1 male, 22.7 by 18.2 mm ( NTOU F10986), Nantow county : Sun-Moon Lake ,, coll. K. Lee & C. L. Lee, Oct. 6. 1999.

Paratypes – Nantow county: Sun-Moon Lake - 1 female (19.4 by 15.8 mm) Nantow county : Sun-Moon Lake , coll. K. Lee & C. L. Lee, Oct. 6. 1999. ( NTOU F10987), coll. K. Lee & C. L. Lee, Oct. 6. 1999 . 1 male (17.2 by 14.1mm) Nantou county: Sun-Moon Lake , coll. K. Lee & C. L. Lee, Oct. 6. 1999. ( ZRC), coll. K. Lee & C. L. Lee, Oct. 6. 1999 .

Others –Nantow county : Sun-Moon Lake - 3 males (27.8 by 21.8 mm, 23.3 by 20.7 mm and 22.7 by 18.6 mm), 3 females (24.3 by 20.0 mm, 23.5 by 19.1 mm and 23.0 by 18.7 mm) Nantow county: Sun-Moon Lake, coll. J. Y. Shy & K. Lee, Mar. 11. 2005. ( NTOU F11020)

Diagnosis. – Carapace smooth, moderately convex longitudinally and transversely. Carapace length and width

1.6 times and 2.0 times of carapace depth, respectively. Frontal region faintly divided into 2 lobes; supraorbital cristae smooth, without granules; infraorbital cristae smooth to almost smooth, sometimes lined with very low granules. External orbital angle sharp. Anterolateral crista distinct, lined with small granules; epibranchial tooth small, just discernible. Postorbital crista rough, with striae. Frontal, orbital, branchial and anterolateral regions covered with weak striae; gastric, cardiac and intestinal regions smooth. Cervical groove faint; H-shaped median gastro-cardiac depression distinct. Posterior margin of epistome with sharp median projection. Distance between tip of closed male abdomen and anterior margin of thoracic sternite 4 about 1.5 times length of thoracic sternites 1-3. External margin of palm smooth; fingers of right chela forming ovate gape when closed. Ambulatory legs of normal length; total length of second leg about 2.0 times carapace length; length of merus about 3.9 times maximum width. Telson of male abdomen bell-shaped. G1 with subterminal segment moderately curving outwards, outer proximal margin with tooth, inner proximal margin moderately dilated; terminal segment straight, distal one-third slender, with spinules and setae; total length of G1 7.0 times of terminal segment; length of synovial membrane about 3.0 times maximum width. G2 with outer proximal margin of basal segment dilated, faintly divided into 2 lobes; distal segment short, about 0.16 times total length.

Colouration. – Carapace and ambulatory legs greenish to orange, sometimes ambulatory legs covered with scattered darker coloured stripes.

Habitat. – Probably in burrows along the banks of the lake under the water.

Size. – Largest male 27.1 by 21.8 mm (NTOU F11020); largest female 24.3 by 20.0 mm (NTOU F11020).

Distribution. – Nantow County, central Taiwan.

Etymology. – The species is named after Miss Kari Lee of the National Taiwan Ocean University, Department of Fishery Science, Crustacean Laboratory, all for her help to find this species.

Remarks. – Although Sun-Moon Lake is a natural freshwater lake at an altitude of about 750m above sea level, this lake experiences a daily tide. During the day, the water is allowed to flow out of conduits into a lower altitude pond to generate hydroelectric power; and the water level gradually decreases. About at midnight, the company utilizes the excess electric power to pump water up from this pond back into Sun-Moon Lake; and the water level rises back up. Under these special conditions, we have been able to find G. leeae only at midnight (i.e. at lowest tide). At this time, we can also find many burrows along the bank which we believe have been dug by the crabs.

Of the known Geothelphusa species in Taiwan, G. olea ( Fig. 4 ) is most similar to the present new species but there are some distinct morphological differences between them, notably in the carapace and gonopods (Table 1). The most obvious difference is the body size of G. leeae , which is smaller than G. olea . Although we have only 9 specimens of G. leeae , the female specimen is already fully mature. Specimens of G. olea , the size of this female as G. leeae is still immature. Another possible difference is their habitat. Although both species live in burrows, their specific habitats are rather different. Geothelphusa olea lives in burrows along the banks of streams above the water, but G. leeae seems to prefer to be underwater. So far, this species is the only lake habitat species of freshwater crab in Taiwan.

Geothelphusa candidiensis ( Fig. 5 ) is also similar to present new species, but we can distinguished by several characters. The major differences are: the epibranchial tooth is small but very clear in G. candidiensis , but is faint in G. leeae ; the G1 outer proximal margin is without a tooth in G. candidiensis but there is a distinct tooth in G. leeae ; and the G1 subterminal segment is almost straight in G. candidiensis but directed outwards in G. leeae .

Figures

Fig. 2. The morphology of Geothelphusa leeae. (A: frontal view. B: dorsal view.)

Fig. 3. Gonapods of Gelthelphusa leeae. A: ventral view of right G.1 terminal segment. B: ventral view of right G1. C: dorsal view of right G1. D: ventral view of right G2. (scale = 1.0 mm)

Fig. 4. Dorsal carapace view and gonopods of Geothelphusa olea. A: ventral view of right G.1 terminal segment. B: ventral view of right G1. C: dorsal view of right G1. D: ventral view of right G2. (dorsal view from Shy & Yu, 1999; gonopods from Shy, 1994; scale = 1.0 mm)

Fig. 5. Gonopods of Geothelphusa candidiensis. A: ventral view of right G.1 terminal segment. B: ventral view of right G1. C: dorsal view of right G1. D: ventral view of right G2. (gonopods from Shy, 1994; scale = 1.0 mm)