Eucyclops prionophorus Kiefer, 1931

Perbiche-Neves, Gilmar, Corgosinho, Paulo H. C., Previattelli, Daniel, Suárez-Morales, Eduardo, Nogueira, Marcos G. & da Rocha, and Carlos E. F., 2025, Catalogue for identification of the most common lacustrine and riverine cyclopoid copepod (Crustacea) species in plankton of La Plata Basin, South America, Zoologia (e 24023) 42, pp. 1-47 : 13-14

Eucyclops prionophorus Kiefer, 1931

Figs 12 , 13

Diagnosis. Adult female, 870 µm in length excluding caudal setae. Simple duct projections in the genital double-somite, not divided by an internal integumental scar as in Eucyclops (Denticyclops) leptacanthus ( Fig. 12A ). Hyaline membrane on the last antennule segment with a finely serrulate pattern ( Fig. 13A ). Caudal ramus 4.6 times longer than wide, outer ornamentation (spinules) without gradual change in size ( Figs 12B , 13B, C ). Inner terminal spine of the last segment of of P4 endopod 1.3 times longer than the segment ( Fig. 12C, D ).

Remarks. Species with a wide geographic distribution in the Americas. It is often found in coastal regions, among aquatic macrophytes and in rivers, and it is seldom found in the plankton of reservoirs. Animals with a dark (black or brownish) color, usually with debris attached to the appendages and body surface due to their benthic habit. This species can be distinguished from congeners by the spinules along the entire outer margin of the caudal rami, and by its proportional width and length.

C

D

Figures

Figure 12. Eucyclops prionophorus, female: (A) genital double-somite, ventral view; (B) caudal rami; (C) P4 right, anterior view; (D) P4 left, anterior view. Scale bars: A, C, D = 50 µm; B = 100 µm.

Figure 13. Eucyclops prionophorus, female: (A) last segment of antennule; (B) caudal rami; (C) caudal rami. Scale bars: A, B = 300 µm; C = 100 µm.