Identification guide to some Diaptomid species (Crustacea, Copepoda, Calanoida, Diaptomidae) of " de la Plata " River Basin (South America) Author Perbiche-Neves, Gilmar Author Boxshall, Geoffrey Allan Author Previattelli, Daniel Author Nogueira, Marcos Gomes Author da Rocha, Carlos Eduardo Falavigna text ZooKeys 2015 497 1 111 http://dx.doi.org/10.3897/zookeys.497.8091 journal article http://dx.doi.org/10.3897/zookeys.497.8091 1313-2970-497-1 F1F6581039D546EA8FC7F3A8B438556C 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). Figure 61. Notodiaptomus incompositus male. A Segments 13-16 of A1R B Caudal seta showing reticulate form C Dorsal view of CR D P5 E First segment of Enp of antenna. Figure 62. Notodiaptomus incompositus male, SEM photographs. A Dorsal view of Ped3, Ped4, Ped5 and GS (100 µm ), showing detail of dorsal rows of spinules B, C P5 (100 µm ) D Segments 10-15 of A1R (100 µm ) E Dorsal view of Ur4 (50 µm ) F Dorsal view of Ur3 (20 µm ) G P5L, and Cx and Bsp of P5R (100 µm ). 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). Figure 63. Notodiaptomus incompositus female. A Posterior part of prosome and GS, showing details of dorsal spinule row B P5. Figure 64. Notodiaptomus incompositus female, SEM photographs. A Dorsal view (100 µm ) B Posterior pedigers and GS (50 µm ) C P5 (100 µm ). 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 Iguacu 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. Figure 65. Geographical distribution of Notodiaptomus incompositus in de la Plata river basin.