14 October 2002 PROCEEDINGS OF THE BIOLOGICAL SOCI DF WASHINGTON 115(3):600-6O4. 2002. A new species of freshwater crab of the genus Potamocarcinus H. Milne Edwards, 1853 (Crustacea: Decapoda: Brachyura: Pseudothelphusidae) from Panama Martha R. Campos and Rafael Lemaitre (MRC) Universidad Nacional de Colombia, Instituto de Ciencias Naturales, AA 103698, Bogota, Colombia, S.A.; (RL) Department of Systematic Biology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560-0163, U.S.A. Abstract.—A new species of freshwater crab from Panama of the genus Potamocarcinus H. Milne Edwards, P. lobulatus, is described and illustrated, bringing to 11 the total number of known species in the genus. The new species is distinguished from other congeners by the morphology of the male first gonopod, especially the presence on the cephalic surface of a prominent and wide distal lobe, and a deep, transverse depression narrowing the spermatic channel. The genus Potamocarcinus H. Milne Ed­ moved P. chacei from Potamocarcinus and wards, 1853 of the Tribe Potamocarcinini even the Potamocarcinini. Ortmann, 1897, currently includes a group While studying specimens of freshwater of ten species distributed from Mexico to crabs in the collections of the National Mu­ northwestern Colombia (Rodriguez 1982, seum of Natural History, Smithsonian In­ 1986, 1992; Prahl & Ramos 1987; Rodri­ stitution, Washington D.C. (USNM), a new guez & Hobbs 1989a, 1989b). Those spe­ species of Potamocarcinus from Panama cies are: P. leptomelus Rodriguez & Hobbs, was discovered, bringing to 11 the total 1989b, from Veracruz, Mexico; P. hart- number of species in this genus. Like other manni Pretzmann, 1975 from Tabasco, species in the genus, this new species herein Mexico; P. chajulensis Alvarez & Villalo- described and illustrated, is characterized bos, 1998 from Chiapas, Mexico; P. mag- primarily by the shape of the male first gon­ nus (Rathbun, 1896), from Chiapas, Mexi­ opod. Terminology for the male first gon­ co, Guatemala, El Salvador, and Costa opod is used according to Smalley (1964) Rica; P. zilchi (Bott, 1956) from El Salva­ and Rodriguez (1982). The abbreviations cb dor; P. aspoeckorum (Pretzmann, 1968), and cl indicate carapace breadth and cara­ from southern Mexico and Honduras; P. ni~ pace length, respectively. Color nomencla­ caraguensis Rathbun, 1893, from Depart­ ture follows Smithe (1975). ment of Granada, Nicaragua; P. armatus H. Milne Edwards, 1853 from Nicaragua, and Family Pseudothelphusidae Rathbun, 1893 Guatemala; P. richmondi (Rathbun, 1893) Tribe Potamocarcinini Ortmann, 1897 from Nicaragua, Costa Rica and Panama; Genus Potamocarcinus and P. colombiensis Prahl & Ramos, 1987 H. Milne Edwards, 1853 from Choco Department, Colombia. Rod­ Potamocarcinus lobulatus, new species riguez (1982) provided a diagnosis of Po­ Figs. 1, 2 tamocarcinus, and temporarily included P. chacei Pretzmann, 1967 in the genus. Sub­ Holotype.—1 male, cl 25.00 mm, cb sequently, Rodriguez & Hobbs (1989a) re­ 37.20 mm, Gamboa, Panama, Atlantic VOLUME 115, NUMBER 3 601 drainage, 6 Jun 1969, leg. L. G. Abele, cles on internal crest, and prominent acute USNM 1004157. spine distally. Chelae (Fig. IC) of both che- Type locality.—Gamboa, Panama, Atlan­ lipeds with palms smooth, somewhat swol­ tic drainage. len; fingers not gaping when closed, tips Diagnosis.—First male gonopod with crossing, surfaces with rows of minute tu­ mesial lobe folded over field of spines. Me­ bercles. sial process triangular, recurved caudoce­ Walking legs (pereopods 2-5) slender phalically, with tip directed downward. Dis­ (Fig. lA). Dactyls each with papillae and 5 tal cephalic surface with deep transverse longitudinal rows of large spines diminish­ depression narrowing spermatic channel, ing in size proximally. Number of spines and prominent, wide, distal lobe. Median and papillae on each dactyl arranged as fol­ cephalic, subapical process with tip re­ lows: 1 anterolateral row and 1 anteroven­ curved caudally. Proximo-lateral process tral row each with 6 spines; 1 external row button-like. Apex elongated mesolaterally. with 5 spines and 1 pair of proximal papil­ Spermatic channel narrow, slit-like. lae; 1 posterolateral row with 5 spines and Description of holotype.—Carapace (Fig. 1 posteroventral row with 4 spines. lA) with cervical groove nearly straight, First male gonopod (Fig. 2) straight, shallow, ending short distance before reach­ slightly expanded laterally at midpoint in ing lateral margin. Anterolateral margin caudal view; with rows of conspicuous se­ with shallow depression behind external or­ tae on distal portion of mesial margin and bital angle; with 4 small, low tubercles be­ scattered short setae on lateral margin. Cau­ tween orbital angle cervical groove, and dal lobe (Fig. 2 E,3) rudimentary. Mesial about 15 teeth beyond cervical groove di­ lobe (Fig. 2 E,2) folded over field of spines. minishing in size posteriorly. Postfrontal Mesial process (Fig. 2 F,l) triangular, re­ lobes small, rounded, delimited anteriorly curved caudocephalically, with tip directed by shallow, transverse depression; median downward. Distal cephalic surface with groove narrow, deep, with incision on up­ deep transverse depression (Fig. 2 F,4) nar­ per margin of front. Surface of carapace in rowing spermatic channel; distal cephalic front of postfrontal lobes flat. Upper border lobe (Fig. 2 F,5) prominent, wide; median of front almost straight, marked with row cephalic, subapical process (Fig. 2 F,6) with of tubercles in frontal view, slightly bilobed distal portion recurved caudally, and me­ in dorsal view; lower margin sinuous in dian incision; proximo-lateral process (Fig. frontal view; surface of front between upper 2 F,7) button-like. Apex elongated mesola­ and lower borders high and slightly exca­ terally. Spermatic channel (Fig. 2E) narrow, vated. Upper and lower orbital margins slit-like. each with row of small tubercles. Surface Color.—Preserved in alcohol, the holo­ of carapace covered with small papillae; type is light brown (near 12IB, Brussels limits between regions weakly demarcated. Brown) with pale brown (Verona Brown, Third maxilliped (Fig. IB) with merus of 223B) specks on the dorsal side of the car­ endognath regularly curved, with shallow apace. The walking legs and chelipeds are depression on distal part of external margin; cinnamon brown (near True cinnamon, 139) exognath approximately 0.54 times length dorsally and ventrally. The ventral surface of ischium. of the carapace is buffy-brown (Sayal First pereopods heterochelous, left che- Brown, 223C). liped larger than the right. Merus with 3 Etymology.—The specific name is de­ longitudinal crests as follows: upper one rived from the Greek lobos, a rounded pro­ with rows of tubercles, internal lower one jection or protuberance. The name refers to with row of teeth, and external lower one the presence of a distal cephalic lobe on the with row of tubercles. Carpus with 5 tuber­ cephalic surface of the male first gonopod. 602 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 1. Potainocarcinus lobulatus, new species, male holotype, USNM 1004157: A, carapace and left pe- reopods, dorsal view; B, left third maxilliped, external view; C, left cheliped, external view. VOLUME 115, NUMBER 3 603 mm Fig. 2. Potamocarcinus lobulatus, new species, male holotype, USNM 1004157: A, left first gonopod, caudal view; B, same, lateral view; C, same, cephalic view; D, same, mesial view; E, same, apex, distal view; F, same, cephalo-lateral view. 1, mesial process; 2, mesial lobe; 3, caudal lobe; 4, transverse depression; 5, distal cephalic lobe; 6, median cephalic, subapical process; 7, proximo-lateral process. 604 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON a distinguishing characteristic of this new Geographie und Biologie der Thiere 10:258- species. 372. Prahl, H. von, & G. Ramos. 1987. Potamocarcinus Remarks.—This new species is most colombiensis sp. nov.: un nuevo cangrejo de similar to Potamocarcinus richmondi. The agua dulce (Decapoda: Brachyura: Pseudothel- two can be distinguished by features of the phusidae) de la Serrania Costera del Baudo, Co­ male first gonopod. The male first gonopod lombia.—Revista de Biologia Tropical 35(1): of P. richmondi has been described and il­ 131-133. Pretzmann, G. 1967. Uber einige siidamerikanische lustrated by Rodriguez (1982:114, fig. 73). Siisswasserkrabben (Pseudothelphusidae) (Vor- The mesial process is not as conspicuously laufige Mitteilung).—Entomologisches Nachri- recurved in the new species P. lobulatus as chtenblatt, Wien 14(2):23-26. in P. richmondi. In P. lobulatus the ce­ . 1968. Neue Siidamerikanische Siisswasser­ krabben der Gattung Pseudothelphusa.—Ento• phalic surface has a prominent, wide, distal mologisches Nachrichtenblatt, Wien 15(1):1- cephalic lobe (Fig. 2 F,5); a median process 15. (Fig. 2 F,6) with a small incision at mid­ . 1975. Die bedornten Arten der Gattung Po­ point and a distal end recurved caudally; tamocarcinus Milne Edwards, 1853.—Annalen and a button-like proximo-lateral process des Naturhistorischen Museum Wien 79:615- 621. (Fig. 2 F,7). In contrast, the cephalic surface Rathbun, M. J. 1893. Descriptions of new species of in P. richmondi has two sharp teeth sepa­ American freshwater crabs.—Proceedings of rated by a wide gap, and a small angled the United States National Museum 16(959): proximal process. The distal cephalic sur­ 649-661, pi. 73-77. face in P. lobulatus has a deep transverse . 1896. Descriptions of two new species of fresh-water crabs from Costa Rica.—Proceed­ depression (Fig. 2 F,4) that narrows the ings of the United States National Museum 18: spermatic channel, whereas no depression 377-379, pis. 29, 30. is present in P. richmondi. Rodriguez, G. 1982. Les crabes d'eau douce d'Amerique. Famille des Pseudothelphusi­ dae.—Faune Tropicale 22:1-223. Acknowledgments . 1986. Centers of radiation of freshwater crabs in the Neotropics. Pp. 51-67 in R. H. Gore & This study was made possible, in part, by K. L. Heck, eds., Crustacean biogeography. a visitor grant awarded to one of us (MRC) Crustacean Issues 4. A. A. Balkema, Rotterdam, 292 pp. from the Office of Fellowships & Grants, . 1992.