Onconeura cascatinha, Wiedenbrug, Sofia, Mendes, Humberto F., Pepinelli, Mateus & Trivinho-Strixino, Susana, 2009

Wiedenbrug, Sofia, Mendes, Humberto F., Pepinelli, Mateus & Trivinho-Strixino, Susana, 2009, Review of the genus Onconeura Andersen et Saether (Diptera: Chironomidae), with the description of four new species from Brazil, Zootaxa 2265, pp. 1-26 : 3-5

Onconeura cascatinha , new species

( Figs 1 A–E)

Type material. Holotype, pharate male, BRAZIL, Rio de Janeiro State, Nova Friburgo, Caledônia, Rio Cascatinha (above dam), 2nd order stream, 1470 m a.s.l., drift, 24.viii.1995, Fittkau. Paratypes, 3 pupal exuviae same data as holotype.

Diagnostic characters. The adult males are separable from all other species by the antenna with 9 flagellomeres, the small inferior volsella and median margin of gonocoxite ventrally with two protuberances bearing setae in addition to superior volsella, oral projections of transverse sternapodeme weak ( Fig. 1 B). The pupae are separable by the fringe with few non-taeniate setae shorter than the length of anal lobe, shagreen on TII–TIV contiguous to caudal spine rows, spines of caudal row on TIV longer than wide and L2 -seta at least as long as half of segment length.

Etymology. The species is named after the type locality. The specific name is to be regarded as a noun in apposition.

Male imago (n=1). Total length 1.29 mm.

Head. AR = 0.37. Antenna with 9 flagellomeres, ultimate flagellomere 78 µm long, at least 1 sensillum chaeticum at third antennal segment. At most 3 sensilla coeloconica at apex of antenna. Temporal setae: 1 inner vertical and at least 1 outer verticals. Clypeus 33 µm long, with 9 setae. Palpomeres length (in µm): 13, 18, 28, 45, 70.

Thorax chaetotaxy (n=3). Antepronotum setae not possible to observe. Dc 7, Pa 3. Scts 6. Legs (mid leg not measurable). Spur of fore tibia 25 µm long; spur of hind tibia 23 µm long. Width of apex of fore tibia 23 µm; of hind tibia 28 µm. Legs measurements as in Table 2.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 180 225 168 55 35 20 35 0.75 3.95 2.41 1.80 p3 195 250 150 90 38 18 35 0.60 3.29 2.97 1.55 Abdomen. Number of setae on tergites I 6, TII 4 – 5, TIII– VIII 4; sternites I 0, SII– VIII 1.

Hypopygium ( Figs 1 A, B). Tergite IX with 8 small setae; laterosternite IX with 1 seta. Superior volsella triangular and wide. Median margin of gonocoxite with two protuberances. Inferior volsella small.

Phallapodeme 28 µm long; transverse sternapodeme 23 µm long. Gonocoxite 88 µm long. Gonostylus 38 µm long; megaseta 8 µm long. HR 2.32, HV 3.36.

Pupa (n=1). Total length 1.5 mm.

Cephalothorax. FS lost. MAps 20 µm and 25 µm. LAps 25 µm. Pc1 8 µm long, Pc2 33 µm long, Pc3 25 µm long. One sensillum near precorneal setae. Dc1 30 µm long; Dc2 20 µm long; Dc3 13 µm long; Dc4 58 µm long. Distance between Dc1 and Dc2 23 µm; Dc2 and Dc3 105 µm; Dc3 and Dc4 8 µm. Wing sheath with at least four rows of pearls.

Abdomen ( Figs 1 C, D). Tergite I and sternite I without shagreen. Tergite II with fine shagreen, points on median region sparse, posteriorly with row of spinules. Tergites III–VIII with coarse shagreen evenly distributed, posterior row of spines followed anteriorly by smaller spinules. Spines of posterior row on TIV longer than wide ( Fig. 1 E). Sternites II–VIII with fine shagreen as Fig 1 D, shagreen extending to parasternites. Conjunctive TII/III with 2 hooklets; TIII/IV with 6 hooklets; TIV/V with 6 hooklets; TV/VI with 6 hooklets; TVI/VII with 6 hooklets.

O-setae present ventral and dorsal in all segments (not drawn). Segment I with 4 D-setae, 1 L-setae, without V-setae. Segment II with 4D, 4V and 3L-setae. Segments III–VII with 5 D, 4V and 4 L-setae. Segment VIII with 2 D, 1 V and 3 L-setae. Segment IV with D1-seta 25 µm long, D5-seta 45 µm long, L1-seta 13 µm long, L2-seta 50 µm long and thick, L3-seta 15 µm long. L4-seta 5 µm long. Segment VIII with D4-seta 30 µm long, D5-seta 38 µm long, L1-seta 13 µm long, L2-seta 58 µm long, L3-seta 13 µm long.

Anal lobe 110 µm long. Anal lobe fringe with lateral 2 stout and shorter setae and 4 short non taeniate setae, one median spur. One anal macrosetae; median setae 108 µm long.

Remarks. Pupal exuviae and the holotype pharate male were collected from a 2nd order stream, 1470 m a.s.l., in central Rio de Janeiro State.

Figures

FIGURE 1. Onconeura cascatinha n. sp. A – B — male, hypopygium, A — detail of tergite IX, dorsal, B — tergite IX removed, sclerites hatched; left: ventral, right: dorsal view with gonostylus removed. C – E — pupal abdomen, C — dorsal view, D — ventral view, E — detail of posterior row of spines on tergite IV.