Potamocarcinus roatensis, Rodríguez & López, 2003

Rodríguez, G. & López, B., 2003, Insular species of Neotropical freshwater crabs (Crustacea: Brachyura), Journal of Natural History 37 (21), pp. 2599-2614 : 2602-2604

Genus Potamocarcinus H. Milne Edwards, 1853 Potamocarcinus roatensis sp. nov. ( figure 1 A–H)

Material examined

Port Royal , Roatan Island, Honduras, 10 March 1979, coll. D. E. Keith, found dead in streambed, one male HOLOTYPE, cl 59.6 mm, cb 98.4 mm ( TU 6267 ); one immature male PARATYPE, cl 16.2 mm, cb 25.1 mm, 17 March 1979, coll. D. E. Keith ( TU6268 ) .

Diagnosis

First male gonopods expanded laterally at middle; apical part bearing two rounded lobes of equal extension, caudal one partially overlapping mesial one, mesial one folded over mesial side and continued toward mesial process; mesial process digitiform, directed mesially; apical cephalic surface with well-developed bifid tooth and shorter lower process, both pointing mesially; field of spines slit-like.

Male holotype description. Carapace 1.65 times as wide as long, with deep and wide cervical groove, curving posteriorly and reaching lateral margin. Anterolateral margin with small postorbital notch, another wider notch at level of cervical groove, seven papillae on margin between these two notches, rest of anterolateral margin covered by 29 small and unequal teeth. Postfrontal lobes well defined, delimited anteriorly by two small scars, median groove obsolete except for slight incision on upper margin of front. Surface of carapace in front of postfrontal lobe flat and inclined anteriorly. Upper margin of front straight in dorsal view, with ill-defined papillae; lower margin visible in dorsal view, with row of papillae, almost straight in frontal view, space between upper and lower margin high. Surface of carapace covered by very small papillae, not visible to naked eye.

First pereiopods heterochelous, right cheliped larger than left. Merus with three crests, external crest with round and scattered papillae, internal upper crest with row of tubercles decreasing in size proximally, internal lower crest with row of small teeth. Carpus with row of teeth on internal crest and prominent acute spine at middle. Inner and outer side of palms of both chelipeds smooth, lower margin with row of scattered small papillae. Palm of larger chela swollen, fingers gaping when closed, tips crossing; palm of smaller chela not swollen, fingers not gaping when closed. Third maxillipeds absent in holotype, in paratype (juvenile) third maxilliped with exognath 0.73 times length of ischium, merus of endognath curved with slight depression on distal part of external margin, orifice of efferent branchial channel open.

First male gonopods robust, expanded laterally at middle in caudal view ( figure 1A). Apical part bearing two rounded lobes of equal extension ( figure 1C: a, b), caudal one partially overlapping mesial one; mesial lobe folded over mesial side and continued toward mesial process ( figure 1D: fml). Mesial process digitiform, directed mesially. Cephalic surface with well-developed bifid tooth and lower shorter process, both pointing mesially. Field of spines slit-like, with mesocephalic border advanced ( figure 1D: mb).

Remarks

The gonopod of this species resembles that of Potamocarcinus magnus ( Rathbun, 1896) , but its mesial lobe is rounded, not subtriangular as in P. magnus , and has a lower apical tooth which is lacking in P. magnus .