Ephemeroporus tridentatus ( Bergamin, 1939 )

Elías-Gutiérrez, Manuel, Kotov, Alexey A. & Garfias-Espejo, Tania, 2006, Cladocera (Crustacea: Ctenopoda, Anomopoda) from southern Mexico, Belize and northern Guatemala, with some biogeographical notes, Zootaxa 1119, pp. 1-27 : 15-17

Ephemeroporus tridentatus ( Bergamin, 1939) ( Figs. 32–35 )

Material examined: Three females from Silvituc ( Mexico).

Body 0.26–0.29 mm, globular, with round posterior margin. No spines at the posteroventral angle but the last two setae from internal margin of valves spiniform and sclerotized ( Fig. 47 ). Antennule shorter than rostrum, with nine aesthetascs and one lateral seta. Second antennae short with setae formula: 0–1–3/0–0–3, and spine formula: 0–0–1/ 0–0–1. Labrum with anterior margin denticulated with at least three well­defined denticles, sometimes four or even five ( Fig. 48 ). When more than three denticles are present on the labrum, the proximalmost ones are smaller than distal ones, and not as wellmarked as the latter. Postabdomen with a preanal angle well­defined, rounded, and covered by small spinules. Number of postanal spines 10–12, with two or three more proximally, noticeably larger than others ( Fig. 49 ). Postabdominal claw with two basal spines, proximal one shorter, and a series of fine spinules along concave margin.

This cladoceran was described as Chydorus tridentatus by Bergamin (1939), and subsequently re­allocated to the genus Ephemeroporus by Frey (1982). Later Paggi (1983) redescribed it based on material from the Paraná River basin. He described the males and found some differences in the spinulation of the postabdomen and two additional spines on the claw, which may be useful in taxonomy. The only difference between Paggi's (1983) description and our material is that the two last setules on the posterior margin of the valves were not setulated in our specimens. All other features were similar. Our record expands the distribution range of this species from South America to South Mexico, thus becoming also the northernmost record of this species.

Figures

FIGURES 32 – 46. Picripleuroxus quasidenticulatus, from Leona Vicario II, Tabasco State, Mexico. Nomenclature of setation pattern follows Chiambeng & Dumont (2004). 32) Lateral view; 33 – 34) Variability of posterior margin of valves; 35 a – b) Variability of labrum shape; 36) A 2, lateral; 37) Postabdomen; 38) Limb I, endites I – III; 39) Limb I, ODL and inner distal lobe IDL; 40) Limb II; 41) Limb III, exopodite and epipodite (GT omitted for simplicity); 42) Limb III, endopodite; 43) Limb IV, exopodite; 44) Limb IV, endopodite; 45) Limb V, endopodite; 46) Limb V, exopodite.

FIGURES 47 – 49. Ephemeroporus tridentatus, from Silvituc lagoon, Campeche, Mexico. 47) Lateral view; 48) Variability of labrum shape; 49) Postabdomen.