Paracyclops chiltoni

Paracyclops chiltoni (G.M. Thomson, 1883) Fig. 35 Diagnosis. Adult female, 1,340 µm in length excluding caudal setae. Inner terminal spine of the last P4-endopod segment 3 times longer than the outer terminal spine (Fig. 35A). Caudal rami 3 times longer than wide (Fig. 35B). P5-outer seta 1.3 times longer than the inner spine (Fig. 35C). Remarks. This species has a wide geographic distribution in the Americas, and may belong to a complex of species. It is frequently found in rivers, littoral zones and among aquatic macrophytes. It can also occur in reservoirs, but seldom in the pelagic zone of storage reservoirs. The genus can be easily recognized by the single row of transverse spinules proximal to the lateral seta of the caudal ramus, different from Eucyclops which generally has spinules along the outer margin, or from Ectocyclops which has several small rows transversely and horizontally. Karaytug (1999) published a world revision and key for Paracyclops.