Notodiaptomus incompositus (Brian, 1926)

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 : 48-49

Taxon classification Animalia Calanoida Diaptomidae

Notodiaptomus incompositus (Brian, 1926) Figs 61, 62, 63, 64, 65

Diaptomus incompositus Brian, 1926

Diaptomus paranaensis Pesta, 1927

Diagnosis.

Adult male, body length 1029 µm. Rows of spinules present dorsally along posterior margins of Ped3 and Ped4 (Fig. 62A), and dorsal surfaces of Ur3 and Ur4 extensively ornamented with patches of small spinules (Fig. 62E, F). Caudal setae modified; each seta with strong plumose setules bilaterally and rounded apex (Fig. 61B, C). Modified seta of segment 13 of A1R strong, with bifid apex and not extending beyond distal margin of segment 14; spiniform process on segment 15 larger than on segment 16 (Figs 61A, 62D). Enp1 of A2 ornamented with pore and spinule row (Fig. 61E). Right BspP5 with internal and outer margins smooth (Fig. 62G). Right Exp1P5 longer than wide; right Exp2P5 cylindrical, internal margin with sclerotized process near middle (Figs 61D, 62B); lateral spine of Exp2P5 inserted subterminally, slightly curved, short, less than 1/3 length of terminal claw (Fig. 62C).

Adult female, body length 1310 µm. Complete suture present between Ped4 and Ped5; transverse row of short spinules present along posterior margin of Ped4 (Fig. 63A); row of long setules, present dorsally on Ped5 (Fig. 64B); lateral wings asymmetrical (Fig. 64A, B), left wing narrower than right, each with two unequal sensillae, large sensilla at apex of wing. Sensilla about 1.5 times longer than wide. GS asymmetrical, approximately 1.5 times longer than wide: slightly dilated anteriorly, with swelling on right side larger than left; sensilla present at apex of each swelling, slightly on dorso-lateral surface on right side (Fig. 63A). P5 symmetrical (Figs 63B, 64C) with small conical process at outer distal corner of CxP5 bearing long blunt sensilla, approximately 2.6 times longer than wide. BspP5 with long external seta, equal in length to external margin of Exp1P5. EnpP5 approximately 3/4 of length of internal margin of Exp1P5. Exp 3-segmented; lateral spine of Exp2P5 as long as external margin of Exp3P5; internal seta of Exp3 about 2.3 times longer than external seta; internal seta reaching almost to middle of terminal claw (Fig. 64C).

Remarks.

This species was collected in the Machadinho Reservoir (MAC-U) on the Uruguay River and it can be easily identified by the unusual form of the caudal setae. It is distributed across the southern part of de la Plata river basin, including southern Brazil, south of the Iguaçu River (Fig. 65), and it also occurs widely in Argentina and Uruguay. In the present study, Notodiaptomus incompositus was among the dominant species and it tended to occur abundantly in reservoirs and river stretches irrespective of their trophic status (eutrophic, mesotrophic, and oligotrophic), as observed for Notodiaptomus henseni . In general, Notodiaptomus henseni was the dominant species in the northern part of de la Plata river basin, while Notodiaptomus incompositus was dominant in the southern sector.