Thermocyclops inversus Kiefer, 1936

Thermocyclops inversus Kiefer, 1936 View in CoL

Fig. 38 View Figure 38

Diagnosis. Adult female, 530 µm in length excluding caudal setae. Lateral arms of genital receptacle are straight ( Fig. 38A View Figure 38 ). Seminal receptacle exceeds ¾ the length of the genital double-somite ( Fig. 38A View Figure 38 ). Caudal rami 3 times longer than wide; the two median setae of the caudal ramus are thicker than in the other Thermocyclops species ( Fig. 38A View Figure 38 ). P4-endopod last segment terminal spine as long as the segment, and slightly shorter or in the same length than the outer terminal spine ( Fig. 38B View Figure 38 ).

The specimen was found in the upper ParanaÍba River, Emborcação Reservoir. The body length of T. inversus from different locations shows wide seasonal and spatial variability. This species has been reported in Brazil, Paraguay, and Central America ( Reid 1989, Perbiche-Neves et al. 2014) and is considered indicative of mesotrophic conditions by some authors (Silva 2011, Perbiche-Neves et al. 2016, 2021).