Oxyurella ciliata Bergamin, 1939 (Figs. 58–64)

Material examined: several females from each of the following localities: Silvituc, Km 51 and Charco 3 (Mexico).

Body 0.38–0.42 mm, oval, posterior margin convex, with postero­ventral angle curved, not armed with spines, with a row of spinules which runs from margin to inner side of valves (Fig. 58). Head with a slight depression in the posterior part. Head shield with main pores not connected, two connected small pores between them (Fig. 60). Rostrum projected with a round tip, covering antennules and partially aesthetascs. Labrum wide not pointed, with a noticeable row of setules along anterior margin (Fig. 61). Second antenna with spine formula: 1–0–1/0–0–1 and setal formula: 0–0–3/1–1–3, in some specimens segments armed with small setules (Fig. 62). Postabdomen with anal spines increasing in size distally, only the distalmost ones smaller (near base of claws). Larger anal spines each with a small bifurcation one third from tip (Fig. 63). Postabdominal claws with one basal spine and a small spinule near the insertion with postabdomen. Lateral setae arranged in groups (Fig. 64).

Oxyurella ciliata (Bergamin, 1939) has been observed in Venezuela by Rey and Vázquez (1986) and Zoppi de Roa and Vasquez (1991). In Central America, a single specimen was found in Lake Peten, Guatemala (Van de Velde et al., 1978). In Mexico, Dimas­Flores (2002) also found a single specimen in the Coatzacoalcos River. All reports are based in one to three specimens so this is a rare cladoceran. Males are not known.