Notodiaptomus santafesinus (Ringuelet & Martinez de Ferrato, 1967)

Perbiche-Neves, Gilmar, Boxshall, Geoffrey Allan, Previattelli, Daniel, Nogueira, Marcos Gomes & da Rocha, Carlos Eduardo Falavigna, 2015, Identification guide to some Diaptomid species (Crustacea, Copepoda, Calanoida, Diaptomidae) of " de la Plata " River Basin (South America), ZooKeys 497, pp. 1-111 : 54-56

Taxon classification Animalia Calanoida Diaptomidae

Notodiaptomus santafesinus (Ringuelet & Martinez de Ferrato, 1967) Figs 69, 70, 71, 72, 73

Diaptomus santafesinus Ringuelet & Martínez de Ferrato, 1967

Diagnosis.

Adult male, body length 967 µm. Dorsal and lateral surfaces of Ped3, Ped4 and Ped5 ornamented with scattered setules (Fig. 70A). Segment 1 of A1R with setule row (Fig. 70H); segment 13 with modified seta reaching beyond middle of segment 14; segments 15 and 16 each with small spinous processes (Figs 69I, 70D); distal margin of segment 20 of A1R terminating in small bifid process (Fig. 69J, K). Tips of rami of P4 ornamented with minute spinule combs (Fig. 70C, G). Left and right CxP5 each with conical process bearing sensilla at apex (Figs 69A, G, 70B, E). BspP5L with smooth inner surface, lacking spinulation or processes (Figs 69A, 70E). Right BspP5 with smooth inner surface, lacking spinulation or processes (Fig. 69A), outer seta short, less than half length of external margin Exp1P5; lateral spine on right Exp2P5 inserted close to insertion of terminal claw, strong and slightly outward curved, approximately four times longer than wide (Figs 69 B–H, 70F); terminal claw with main curvature in proximal 1/3.

Adult female, body length 1271 µm. Incomplete suture present between Ped4 and Ped5; lacking rows of spinules on posterior margin of pedigers (Fig. 71A). Dorsal process present on midline of Ped4 (Fig. 71A, C); lateral wings slightly asymmetrical; both projections with pair of sensillae, one large and one small. GS slightly asymmetrical, about 1.8 to 1.9 times longer than wide; anterior part slightly dilated, with sensilla at apex of each swelling; left sensilla positioned slightly anterior to right; left sensilla directed slightly posteriorly, right sensilla directed slightly anteriorly. P5 symmetrical (Figs 71D, 72A) with small conical process at outer distal corner of CxP5, bearing sensilla approximately 1.5 times longer than wide; BspP5 with external seta of medium length, not exceeding length of internal margin of Exp3P5. EnpP5 unsegmented, reaching middle of inner margin of Exp1P5. Exp 3 -segmented; lateral spine of Exp2P5 shorter than external margin of Exp3; external seta of Exp3 about half length of internal seta; internal seta almost reaching middle of terminal claw (Fig. 72B).

Remarks.

The specimens examined were collected in the lower stretch of the Paraguay River ( RPAG–B). This species is found in Argentina in the middle and lower stretches of the Paraná River and it can be considered to be a common species in the zooplankton community of this region (Fig. 73). However, Ringuelet and Martínez de Ferrato (1967) found that this species was uncommon during the period of their study, occurring in lotic or adjacent systems only between February and April. It was not found in reservoirs. This species can be readily distinguished from its congeners because of the position of the robust lateral spine on the right Exp2P5, close to the insertion of the terminal claw.