Eurycercus (Eurycercus) cf. lamellatus (O. F. Müller, 1776)

Bekker, Eugeniya I., Kotov, Alexey A. & Elmoor-Loureiro, Lourdes M. A., 2010, The genus Eurycercus Baird, 1843 (Cladocera: Eurycercidae) in the Neotropics, Journal of Natural History 44 (41 - 42), pp. 2481-2508 : 2483-2484

Eurycercus (Eurycercus) cf. lamellatus (O. F. Müller, 1776)

( Figure 1 )

Material studied

One juvenile female from lower reaches of Rio Nhamundá, Central Amazonia, Pará, Brazil, AAK 2003-030 .

Short description of single juvenile female

In lateral view body subrectangular ( Figure 1A ). Dorsal margin interrupted by a relatively shallow depression behind major head pore. In anterior view, body moderately compressed laterally, median dorsal keel well developed, although not sharp ( Figure 1B ). Head with relatively long rostrum. Compound eye relatively small, ocellus was not found, but the pigment could have been dissolved by irregularities in the preservation technique. A single major “head pore” as a ringed, suboval field of special cuticle; a minute, elongated ovoid lateral pore located at either side of major pore, closer to it ( Figure 1C ). Labrum with a medium-sized median keel, terminating in a broadly rounded apex. Postabdomen with subparallel dorsal and ventral margins. Distal anal embayment shallow. Armature of the preanal margin as a series of 101 preanal teeth in the examined specimen; teeth in middle of preanal margin with sharp tips. Spines at base of preclaw portion short, predominantly single ( Figure 1D ). Postabdominal claw robust, first (distalmost) basal spine long, second (basalmost) spine short. Antenna I relatively short, protruding greatly beyond tip of rostrum and reaching labral apex. Antennular sensory seta arising approximately in antenna I middle. Limbs not studied. Intestine has a single loop. Length 0.82 mm.

Distribution

This is a common Palaearctic taxon; our finding of a single specimen in a single locality is the first adequate record of E. lamellatus (or its closest congener) in Brazil. See Discussion.

Figures

Figure 1. Eurycercus cf. lamellatus, juvenile female from lower reaches of Rio Nhamundá, Central Amazonia, Pará, Brazil. (A) Lateral view; (B) anterior view; (C) dorsal head pores; (D) postabdominal claw. Scale bars: 0.1 mm.