Notodiaptomus spiniger (Brian, 1925)

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 : 57-60

Taxon classification Animalia Calanoida Diaptomidae

Notodiaptomus spiniger (Brian, 1925) Figs 74, 75, 76, 77, 78

Diaptomus spiniger Brian, 1925

Argyrodiaptomus spiniger (Brian, 1925)

Diaptomus toldti Pesta, 1927

Notodiaptomus orellanai Dussart, 1979

Diagnosis.

Adult male, body length 1466 µm. Patches of spinules present dorsally and laterally along suture between Ped3 and Ped4 (Figs 74B, C, 75A), and on the surface of Ur3 and Ur4 (Fig. 75E). Modified seta well developed on segment 13 (Fig. 74D, Q) and spinous process well developed on segment 15 of A1R (Figs 74Q, 75H); segment 20 of A1R typically produced into distal falciform process, longer than wide (Figs 74J, 75D, F), but process sometimes absent (see Dussart and Frutos 1985). End1 of A2 ornamented with spinule row, lacking pore (Fig. 74I). Rounded mammiform process present on internal margin of right BspP5 (Figs 74A, P, 75B, G). Left CxP5 1.5 times longer than wide; BspP5L about 1.2 longer than wide (Fig. 74 K–M). Lateral spine of right Exp2P5 straight, almost as long as segment, inserted close to origin of terminal claw; terminal claw long, approximately 3 times as long as lateral spine (Figs 74 F–H, N, O, R, 75C).

Adult female, body length 1688 µm. Complete suture present between Ped4 and Ped5; with several irregular rows of spinules present dorsally along posterior margin of Ped4 (Figs 76A, 77 A–C); lateral wings slightly asymmetrical, left wing larger than right; both wings bearing pair of sensillae, one large and one small; large sensilla on left side located on hemispherical projection, right sensilla located on apex of wing (Fig. 77C). GS asymmetrical, about 1.5 times longer than wide; anterior part slightly dilated, with swelling on left side larger than on right, sensilla present on apex of each, both about twice as long as wide; sensilla on right side directed perpendicular to long axis of body (Fig. 76A). Right margin of GS longer than left. Cx of P1 with spinules on antero-lateral surface (Fig. 77G). P5 symmetrical (Fig. 76B) with small conical process at distal corner of CxP5, bearing triangular sensilla approximately 1.8 times longer than wide. BspP5 with outer seta of medium length, reaching middle of external margin of Exp1P5 (Fig. 77D). EnpP5 one-segmented, slightly longer than internal margin of Exp1P5. Exp 3-segmented; lateral spine of Exp2P5 long, reaching middle of external seta of Exp3P5 (Fig. 77E); internal seta of Exp3P5 about 3.5 times longer than external seta of Exp3P5; internal seta of Exp3P5 extending beyond middle of terminal claw.

Remarks.

The illustrated specimens were caught in the upper reaches of the Uruguay River, in the Machadinho Reservoir. The northernmost boundary of its distribution may lie in the northern sector of Paraná State (Brazil), its northernmost record is from the floodplain of the upper Paraná River (Fig. 78).

This species has been the subject of much taxonomic confusion. Ringuelet and Martínez de Ferrato (1967) argued that misinterpretation of the intraspecific variability of the spinous processes on segment 15 and of the falciform process on segment 20 of the male A1R is responsible for the establishment of " Diaptomus " toldti Pesta, 1927, a junior subjective synonym of Notodiaptomus spiniger . They added that individuals with well-developed spinous processes typically had a larger body size. Brehm (1933) included this species in the genus Argyrodiaptomus , but Kiefer (1936) doubted its inclusion in the genus because of its possession of a mammiform process on the internal margin of the right BspP5 and thus suggested an affinity with Notodiaptomus . Some subsequent authors (e.g. Ringuelet and Martínez de Ferrato 1967) have placed this species in " Diaptomus " as Diaptomus spiniger , while Dussart and Defaye (2002) treated it as incertae sedis within Argyrodiaptomus .

There are two other synonyms: " Diaptomus " birabeni Brehm, 1957 and Notodiaptomus orellanai Dussart, 1979 as proposed by Paggi in his MS Thesis in 1994. In each case the new species was established on the basis of morphological characters ( Brehm 1957, Dussart 1979), but both synonymies are now widely accepted.

Further study of this species is necessary, including study of museum collections, in order to verify these synonymies and assess the evidence supporting the placement of this species in the genus Notodiaptomus , in part because of the presence of a mammiform process on the internal margin of the right BspP5, a character which conflicts with the current diagnosis of the genus.