Onconeura oncovolsella, 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 : 9-13

Onconeura oncovolsella , new species

( Figs 4 A–G, 5 A–F)

Thienemanniella semifimbriata -Gruppe spec. 4: Wiedenbrug 2000: 96.

Type material. Holotype male with pupal and larval exuviae, BRAZIL, São Paulo State, Ubatuba, Sertão da Quina, Sítio Santa Cruz, Cachoeira do Engenho, 23°31.068´S, 45°14.845´W, 23 m a.s.l., 8.x.2007, S. Wiedenbrug. Paratypes: Allotype female with pupal exuviae, Ubatuba, Sertão da Quina, Cachoeira da Renata near parking lot, 23°31.087´S, 45°14.621´W, 39 m a.s.l., 14.i.2008, S. Wiedenbrug; one female with pupal exuviae, same data as holotype; one male and one female both with pupal and larval exuviae, same data as holotype except for 14.x.2008; one male with pupal and larval exuviae, Ubatuba, Sertão da Quina, Cachoeira da Renata upstream, 23˚30.789´S, 45˚14.442´W, 61 m a.s.l., 15.x.2008, S.Wiedenbrug.

Additional material. Pupal exuviae, Brasil, Rio Grande do Sul State, São Francisco de Paula, Arroio dos Carros, 23.xi.1994, S. Wiedenbrug.

Diagnostic characters. The adult males are separable from other species by the antenna with 8 – 9 flagellomeres, the large superior volsella with a concave posterior margin, median margin of gonocoxite straight, without protuberances. Adult females are separable by the small wings, the shape of the apodeme lobe. The pupae are characterized by having 3 L-setae on segments III–VII; anal lobe fringe about as long as length of anal lobe, SII with shagreen as in figure 5B. The larvae are separable by AR 1.74 and mentum with median tooth as long as adjacent teeth.

Etymology. From Latin uncus meaning hook, referring to the hook shaped superior volsella of the male.

Male imago (n=1 – 2). Total length 1.03 – [1.13] mm. Wing length [0.55] mm. Total length/wing length 1.87 – [2.05] Wing length/ length of profemur [2.75]. Color (specimen preserved in alcohol): thorax yellowish with brownish vittae, scutellum, postnotum and preepisternum. Abdominal segments I–IV, gonocoxite and gonostylus yellowish, rest brownish. Legs yellowish but following structures brownish coxa and trochanter, ring distal on femur and proximal on tibia, and distal on ta1.

Head. AR= [0.38] – 0.40. With 8 – [9] flagellomeres, ultimate flagellomere [200] – 212 µm long, at least one sensillum chaeticum at second, third and last flagellomere. Temporal setae: 0–1 inner vertical and 2 outer verticals. Clypeus [33] – 40 µm long, with 8 – 9 setae. Tentorium [98] µm long; 8 – [10] µm wide. Palpomeres length (in µm): [15] – 17, 15 – [18], 28 – [30], 40 – [43], 67 – [70]. Third palpomere with one sensillum clavatum.

Thorax chaetotaxy. Aps 2 – 3, Dc 9 – 10, Pa 3, Scts 2 – 4.

Wing ( Fig. 4 A). VR 1.70 – [1.96]. Clavus [23] – 28 µm wide; ending [180] – 187 µm from arculus; with 1 seta. Clavus/wing length [0.33]. Anal lobe reduced.

Legs. Spur of fore tibia [30] µm long; spurs of middle tibia [13] and [18] µm long; spurs of hind tibia [13] and [25] µm long. Width of apex of fore tibia [18] µm; of middle tibia [20] µm; of hind tibia [25] µm. Legs measurements as in Table 5.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 200 195 145 –148 48 30 20 25 0.74 –0.76 4.39 2.67– 2.72 2.00 p2 240 233 –235 130 –133 68 30 15 25 0.56 –0.57 4.37 3.53– 3.64 1.33 p3 200– 203 218–225 145 85 25 15 28 0.67 3.70 3.09 1.67 Abdomen. Number of setae on tergites II–VI 4, TVII 4 – 5, TVIII 0; sternites II–IV 1, SV– VI 1–2, SVII 1, SVIII 3.

Hypopygium ( Figs 4 B, C) Tergite IX with 9 – 14 small setae with a notch on posterior margin. Sternite IX with 1 seta. Superior volsella [10] µm long, triangular, wider posteriorly, posterior margin concave. Inferior volsella large and triangular, with straight median margin. Phallapodeme [35] – 38 µm long; transverse sternapodeme 30 – [38] µm long. Gonocoxite [88] – 95 µm long. Gonostylus [33] µm long; megaseta [8] µm long. HR [2.67] – 2.87, HV 3.12 – [3.42].

Female imago (n=1–2). Total length 1.03 mm. Wing length 0.57 mm. Wing length/length of profemur 3.00.

Head. AR 0.37 – 0.38. Apical flagellomere 33 µm long; two sensilla chaetica in flagellomeres 2 – 5. Temporal setae: 1 inner vertical, 2 outer verticals. Clypeus 33 – 38 µm long, with 10 – 11 setae. Tentorium 55 – 58 µm long, 5 µm wide. Palpomeres length (in µm): 18 – 20, 17 – 18, 27 – 30, 35 – 37, 53 – 65. One sensillum clavatum on palp 3.

Thorax chaetotaxy. Aps 3, Dc 9, Pa 2, Scts 3.

Wing. VR 1.8. Clavus 38 µm wide; ending 295 µm from arculus; with 7 setae. Clavus/Wing length 0.52.

Legs. Spur of fore tibia 23 µm long; spur of middle tibia 18 µm long; spurs of hind tibia 15 and 25 µm long. Width of apex of fore tibia 18 µm; of middle tibia 18 µm; of hind tibia 23 µm. Legs measurements as in Table 6.

TABLE 6. Legs measurements (in µm) and ratios of Onconeura oncovolsella new species, female.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 162–190 165–195 122–138 48 28 20 28 0.71–0.74 4.22 2.72–2.79 1.50 p2 225–230 229–230 123–126 63 30 18 28 0.55–0.56 4.22 3.62–3.65 1.54 p3 175–200 200–210 125–138 88 25 15 28 0.63–0.66 3.51 2.97–3.00 1.53 Abdomen. Number of setae on tergite I not observed, TII– VI 4, TVII 4 – 5, TVIII 0; sternites I–IV not observed, SV– VII 1, SVIII 0.

Genitalia ( Figs 4 D, E). Gonocoxite with 2 setae. Tergite IX with 8 – 10 setae. Cercus 42 – 50 µm long. Seminal capsules 38 – 40 µm long, 38 – 40 µm wide. Notum 30 – 37 µm long. Apodeme lobe rounded distally large, not sclerotised. Labia basally fused caudally slightly divided and rounded.

Pupa (n=1 – 2). Total length 1.4 mm.

Cephalothorax. FS lost. Po 18 µm and 8 µm; Longest MAps 43 µm and 25 µm. LAps 8 µm and 10 µm. Pc1 5 – 8 µm long, Pc 2 18 – 45 µm long, Pc3 10 µm long. One sensilla near precorneal setae. Dc 1 20 – 22 µm long; Dc 2 10 – 15 µm long; Dc 3 8 – 10 µm long; Dc4 63 – 65µm long. Distance between Dc1 and Dc 2 20 – 27 µm; Dc2 and Dc3 77 – 132 µm; Dc3 and Dc4 2 – 7 µm. Wing sheath with two to five rows of pearls.

Abdomen ( Fig. 5 A, B, C). Tergite I and sternite I without shagreen. Tergite II with few shagreen points grading to a row coarse shagreen points posteriorly. Tergites III–IX with fine shagreen grading to a row of coarse shagreen points and a row of spinules posteriorly. Sternite II with posterior needle-like spinules ( Fig. 5 B). Sternites III–VIII with very fine shagreen. Sternites V–VIII posterior with one to two rows of small spinules. Sternite VIII on female with fine shagreen only and low broad posterior projection. Conjunctive TII/ III with 0 – 1 hooklets; TIII/IV with 4 – 6 hooklets; TIV/V with 5 – 6 hooklets; TV/VI with 4 – 6 hooklets; TVI/ VII with 3 – 5 hooklets.

O-setae present ventral and dorsal in all segments (not drawn). Segment I with 4 D-setae, 1 L-setae very long, without V-setae. Segments II–VII with 5 D, 4V and 3 L-setae. Segment VIII with 2 D, 1 V and 3 Lsetae. Segment IV with D1-seta 25 – 35 µm long, D5-seta 43 – 50 µm long, L1-seta 8 – 17 µm long, L2-seta 53 – 83 µm long and thick, L3-seta 8 – 15 µm long. Segment VIII with D4-seta 27 – 58 µm long, D5-seta 80 – 105 µm long and thick, L1-seta 10 – 17 µm long, L2-seta 62 – 75 µm long, L3-seta 18 – 20 µm long.

Anal lobe 103 – 115 µm long ( Fig. 5 C). Anal lobe fringe with lateral 3 – 6 stout and shorter setae and median 3 – 5 taeniate setae; taeniate setae 137 – 145 µm long, one median spur. Anal macrosetae 43 µm long; median setae 145 – 155 µm long.

Larva (n=1 – 2). Head. Capsule length 187 – 200 µm, width 125 µm. Ventral head length 135 – 138 µm. Ventral head length/width 1.10. SI bifid. Premandible with an outer lateral brush. Median tooth of mentum as long as adjacent teeth ( Fig. 5 D). Distance between seta submentalis 40 – 50 µm. Mandible ( Fig. 5 E) length 50 – 55 µm. Antennae ( Fig. 5 F). AR 1.74 – 1.76. Length of segment I 30 – 40 µm; basal segment width 10 µm; antennal blade 15 µm long; ring organ at 8 µm from the base of first antennal segment.

Abdomen. Longest abdominal seta, 108 µm. Procercus 18 µm high and 18 µm wide. Subbasal seta on posterior parapod simple, 53 µm long.

Remarks. Most of the larvae were found on the surface of stones of fast flowing waters but a few were also collected from litter. This species was collected in low order streams from São Paulo and Rio Grande do Sul, but a wider range could be expected.

Figures

FIGURE 4. Onconeura oncovolsella n. sp. A – C — male, A — wing, B — hypopygium, tergite IX removed, sclerites hatched, right: ventral view, with gonostylus removed, C — hypopygium, detail of tergite IX, gonocoxite and gonostylus, dorsal, D – G — female genitalia, D — dorsal view, E — ventral view, left with gonapophysis removed, F — apodeme lobe, G — labia, H — vaginal opening.

FIGURE 5. Onconeura oncovolsella n. sp. A – C — pupa, A — abdomen, dorsal view, B — sternite II, C — sternite VIII and anal lobe. D – F — larva, D — mentum, E — mandible, F — antenna.