PROC. BIOL. SOC. WASH. 98(3), 1985, pp. 615-621 FRESHWATER SHRIMPS FROM VENEZUELA III: MACROBRACHIUM QUELCHI (DE MAN) AND EURYRHYNCHUS PEMONI, N. SP.; (CRUSTACEA: DECAPODA: PALAEMONIDAE) FROM LA GRAN SABANA Guido Pereira Abstract. —Macrobrachium quelchi (De Man), not collected since the original description, is redescribed and the color pattern is given. Euryrhynchus pemoni, new species, the fourth species in the genus, is described. The material comes from La Gran Sabana, a large highland plateau in the southeast Venezuela (6°15'N, 60 o l'W), in the headwaters of rivers that discharge into the Orinoco River basin. Freshwater palaemonid shrimps represent a large group of crustaceans that inhabit brackish and freshwater habitats throughout the tropics. American species living in brackish water and rivers discharging directly into the sea are, at present, well known (Holthuis 1952; Chace and Hobbs 1969). However, in South America, especially in the Amazon region, there are many tributary streams with almost no connection with the estuarine zone of the main river. Shrimp species from these rivers are not well known, and recent surveys have yielded several new species (Tiefenbacher 1978; Rodriguez 1982; Kensley and Walker 1982; Pereira, in press). Several species of freshwater shrimps from southern Venezuelan rivers are not dependent on saline water for their development (Rodriguez 1981; Pereira 1 982). La Gran Sabana, located in this zone, represents an altiplane (1200 m above sea level) consisting of a vast system of creeks and streams (of both black and clear waters) which drain into the Caroni River. This black-water river is one of the main tributaries of the Orinoco River basin. This paper describes two interesting palaemonid shrimps from La Gran Sabana. Macrobrachium quelchi was known only from the original description in 1900 from the the Upper Mazaruni River (Esequibo River basin) Guyana. The other shrimp represents a new species of Euryrhynchus, a fairly homogeneous group of shrimps with an Amazonian distribution (Tieffenbacher 1978). Abbreviations tl and cl are used for total length and carapace length respectively, measured from tip of rostrum to tip of telson, and posterior orbital margin to posterior edge of cephalothorax. MBUCV, Museum of Biology, Central University of Venezuela. USNM, National Museum of Natural History, Smithsonian Institution. Macrobrachium quelchi (De Man) Figs. 1, 2, 3, 4 Palaemon (Macrobrachium) quelchi De Man, 1900:57, pi. 6, figs. 1-8. Material examined. —MBUCV (XI-2111) 3 <3, 2 9; stream tributary of River Kama. La Gran Sabana, Bolivar State, Venezuela (6°15'N; 60°1'W), 29 Mar 1983,
Fresh water Shrimps From Venezuela .3. Macrobrachium quelchi (De Man) And Euryrhynchus pemoni, N-Sp - (Crustacea, Decapoda, Palaemonidae) From La Gran Sabana
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