Onconeura similispina, 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 : 14-18

Onconeura similispina , new species

( Figs 6 A–G, 7 A–I)

Thienemanniella semifimbriata -Gruppe spec. 3: Wiedenbrug 2000: 95.

Type material. Holotype male, with pupal and larval exuviae, BRAZIL, São Paulo, Ubatuba, Sertão da Quina, Cachoeira da Renata upstream, 23˚30.789´S, 45˚14.442´W, 61 m a.s.l., 04.i.2008, S. Wiedenbrug. Allotype female, with pupal and larval exuviae, same data as holotype. Paratypes all with pupal and larval exuviae: one male and one female same data as holotype; one male, same data as holotype, except for near Sítio Santa Cruz, 23°31.231´S, 45°14.625´W, 33 m a.s.l., 2.v.2007, S. Wiedenbrug; one male and one female, as previous, except for Cachoeira do Engenho, 23˚31.068´S, 45˚14.845´W, 23 m a.s.l., 14.x.2008, S. Wiedenbrug; one female same data as previous, except for 8.x.2007. One male and one female, São Paulo State, Parque Estadual do Jaraguá, São Paulo, stream near playground, 14.iv.2007, S. Wiedenbrug; one male, same data as before except for 11.ii.2008 (UFSCAR MPSW 01); one female same data as previous except for spring on the way to the peak of Jaraguá, 9.ix.2007.

Additional material. 1 pharate male, Rio Grande do Sul State, Taquara, Arroio do Mineiro, 19.xi.1994, G. B. Buckup and S. Wiedenbrug. 1 pharate male, same data as previous but 15.xi.1994. 3 pupal exuviae, same data as previous. 10 pupal exuviae, Rio Grande do Sul State, São Francisco de Paula, Arroio dos Carros, 15 and 26.xi.1994. S. Wiedenbrug.

Diagnostic characters. The adult males are separable from other species by the antenna with 12 flagellomeres, tergites with at most 6 setae, LR1=0.92 – 1.00, by the laterosternite IX with one seta and wing without anal lobe. Adult females are separable by total length, LR1, the shape of the gonapohysis VIII and apodeme lobe. The pupae are separable by having 4 L-setae on segments III–VII, L2- seta of segment VIII not reaching lateral corner of anal lobe; anal lobe fringe longer than twice as long as anal lobe length, points of shagreen on sternite II as long as points of shagreen on sternite III. The larvae can be recognized by the median tooth usually shorter than adjacent teeth; AR 2.33; ventral head length 177 – 193 µm. O. similispina tends to be larger than O. japi , but no other diagnostic character was found to identify both species.

Etymology. From Latin similes meaning similar and spina meaning spine, referring to the pupal diagnostic character, the similarity between the shagreen points (or small spines) on sternites II and III.

Male imago (n=2 – 4, except where otherwise stated). Total length [1.26] – 1.37 mm. Wing length 0.72 – 0.75 mm. Total length/wing length [1.94]. Color (specimen preserved in alcohol): thorax light brown with dark brown vittae, scutellum, postnotum and preepisternum. Abdominal segments and hypopygium brownish, except for yellowish spots of setae from tergites and on cleared males yellowish rectangle at tergites VI and VII extending from row of setae to posterior margin. Legs with light brown ground colour, coxa and ring distal on femur and proximal on tibia brown.

Head. AR= [0.33] – 0.47. With 12 flagellomeres, ultimate flagellomere [100] 115 – 134 µm long, 2 sensilla chaetica at second antennal segment. At most 3 sensilla coeloconica at apex of antenna. Temporal setae: 1 inner vertical and 2 outer verticals. Clypeus [42] – 50 µm long, with 10 – 11 setae. Tentorium [105] – 115 µm long; [17] – 22 µm wide. Palpomeres length (in µm): [17] 12 – 25, [20] – 32, [42] 37 – 47, [67] 62 – 70, [100] – 110. Third palpomere with two sensilla clavata.

Thorax chaetotaxy. Aps 1–6, Dc 11 – 13, Pa 3, Scts 4 – 5.

Wing ( Fig. 6 A). VR [1.79] 1.66 – 1.82. Clavus [30] – 45 µm wide; ending [245] 237 – 265 µm from arculus; with 1 seta at apex. Clavus/wing length [0.34] 0.32 – 0.36.

Legs. Spur of fore tibia 35 – 37 µm long; spurs of middle tibia 20 and 12; spurs of hind tibia 27 – 37 and 15 – 17 µm long. Width of apex of fore tibia 20 – 25 µm; of middle tibia 20 – 25 µm; of hind tibia 27 – 30 µm. Legs measurements as in Table 7.

Abdomen. Number of setae on tergites I 6, TII 4 – 5, TIII– VIII 5; sternites I–II 0, SIII, V–VII 1 – 2, SIV 1 – 3, SVIII 2 – 3.

Hypopygium ( Figs 6 B, C). Tergite with 9 – 14 small setae; laterosternite IX with 1 seta. Superior volsella low. Inferior volsella relatively short, posterior margin not deeply concave. Phallapodeme 32 – [37] µm long; transverse sternapodeme [32] 27 – 35 µm long. Gonocoxite [95] – 102 µm long. Gonostylus [37] – 40 µm long; megaseta [7] µm long. HR 2.42 – [2.56], HV [3.41] 3.36 – 3.43.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 265–290 245–260 235–245 65–70 40–45 27–32 27–35 0.92–1.00 4.25–4.84 2.20–2.30 2.0–2.7 p2 345–390 300–315 207–225 95–97 47–50 27 37 0.68–0.72 4.16–4.40 3.12–3.25 1.47–2.08 p3 275–290 305–320 200–225 110–115 45–47 27 37–40 0.69–0.70 3.61 2.78–2.79 1.35–1.37 Female imago (n=2 – 4). Total length 1.3 – 1.9 mm.

Wing length 0.66 – 0.77 mm. Wing length/length of profemur 2.71 – 2.89.

Head. AR 0.37 – 0.48. Apical flagellomere 40 – 52 µm long; two sensilla chaetica in flagellomeres 2 – 5. Temporal setae: 1 inner vertical, 3 – 4 outer verticals. Clypeus 50 – 60 µm long, with 8 – 14 setae. Tentorium 82 – 87 µm long, 12 – 15 µm wide. Palpomeres length (in µm): 20 – 22, 25 – 27, 42 – 45, 57 – 67, 95 – 110. Sensilla clavata 1 – 2 on palp 3.

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

Wing. VR 1.48 – 1.71. Clavus 42 – 50 µm wide; ending 335 – 375 µm from arculus; with 6 – 8 setae. Clavus/ Wing length 0.49 – 0.53.

Legs. Spur of fore tibia 27 µm long; spur of middle tibia 22 – 25 µm long; spurs of hind tibia 27 – 35 and 17 µm long. Width of apex of fore tibia 22 µm; of middle tibia 22 – 25 µm; of hind tibia 25 – 27 µm. Legs measurements as in Table 8.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR* p1 220–250 217–260 217–200 50–62 37–45 27–30 35 0.83–85 4.34–4.60 2.36–2.44 1.42 p2 290–335 270–310 172–212 85–92 42–47 27–30 35–37 0.66–0.68 3.80–4.02 3.04–3.20 1.18 p3 237–275 260–290 172–200 107–110 40–45 22–25 30–37 0.65–0.74 3.48–3.55 2.71–2.92 1.25

* n=1

Abdomen. Number of setae on tergites I, III, IV, V 4 – 5, TII 3 – 5, TVI– VII 5, VIII 2 – 3. Sternites I–II 0, SIII 0 – 2, SIV– VI 1 – 2, SVII 0 – 3, SVIII 0.

Genitalia ( Figs 6 D, E). Gonocoxite with 2 – 3 setae. Tergite IX with 4 – 7 setae. Cercus 50 – 57 µm long. Seminal capsules 37 – 45 µm long. Notum 42 – 50 µm long. Labia basally fused, caudally rounded ( Fig. 6 G), with a small median notch. Gonapophysis VIII inner margin slightly directed to posterior. Apodeme lobe with a sclerotized point directed to posterior ( Fig. 6 F)

Pupa (n=1 – 4). Total length 1.9–2.1 mm

Cephalothorax. FS 153 µm long. Longest Po 25 µm. Longest MAps 78 µm and 25 µm. LAps 23 µm. 3 Precorneal setae Pc2 44 – 93 µm long. One sensillum near precorneal setae. Dc 1 23 – 45 µm long; Dc 2 15 – 42 µm long; Dc3 5 – 8 µm long; Dc4 110 – 140 µm long. Distance between Dc1 and Dc 2 15 – 23 µm; Dc2 and Dc3 93 – 123 µm; Dc3 and Dc 4 5 – 15 µm. Wing sheath with at least four rows of pearls.

Abdomen ( Figs 7 A, B, C). Tergite I and sternite I without shagreen. Tergite II–IV with few and fine shagreen points anteriorly. Shagreen points getting coarse and distributing more posteriorly on tergites from posterior segments. Tergites II–VIII with posterior row of spines followed anteriorly by smaller spinules. Sternites II–IV with fine shagreen, shagreen extending to parasternites. Sternites V–VIII posterior with fine shagreen, points getting stronger posteriorly. Sternite VIII on female with fine shagreen only and low broad posterior projection. Conjunctive TII/III with 0 – 3 hooklets; TIII/IV with 5 hooklets; TIV/V with 5 hooklets; TV/VI with 4 – 5 hooklets; TVI/VII with 2 – 4 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. Segment II with 4 D, 3V and 3 L-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 40 – 70 µm long, D5-seta 58 – 88 µm long, L1-seta 15 – 30 µm long, L2-seta 87 – 105 µm long and thick, L3-seta 25 – 45 µm long. L4-seta 8 – 10 µm long. Segment VIII with D4-seta 40 – 63 µm long, D5-seta 35 – 48 µm long, L1-seta 13 – 18 µm long, L2-seta 63 – 90 µm long, L3-seta 18 – 20 µm long

Anal lobe 160 – 188 µm long ( Fig. 7 C). Anal lobe fringe with lateral 3 – 4 stout and shorter setae and 18 – 24 taeniate setae; taeniate setae 345 – 425 µm long, one median spur. Anal macrosetae 40 µm long; median setae 175 µm long.

Larva (n=1–3). Head. Capsule length 255 – 300 µm, width 168 – 198 µm. Ventral head length 177 – 193 µm (n=6). Ventral head length/width 1.09 – 1.13. Labrum with scalloped antero-median margin, SI bifid, SII large, rising from small tubercle, SIII thin between SI and SII ( Fig. 7 D). With two pairs of chaetulae laterals: one median pair, and one pectinate marginal pair. Two pairs of pectinate chaetulae basales ( Fig. 7 E). Premandible with an outer lamella with a brush. Mentum as in figure 7F. Mandible length 73 – 83 µm ( Fig.7 G). Distance between seta submentalis 50 – 55 µm. Antennae ( Fig. 7 H). AR 2.17 – 2.50. Length of segment I 63 – 75 µm; basal segment width 10 – 15 µm; antennal blade 15 – 18 µm long; ring organ at 15 – 30 µm from the base of first antennal segment.

Abdomen. Longest abdominal seta, 133 – 175 µm. Procercus 23 µm high and 18 – 20 µm wide. Subbasal seta of posterior parapod 73 – 95 µm long, apically split or not.

Remarks. Most of the larvae were collected from litter but they were also collected from the surface of stones. The species has been found in low order streams in the mountainous regions along the coast of São Paulo and Rio Grande do Sul State.

Figures

FIGURE 6. Onconeura similispina n. sp. A – C — male, A — wing, B — hypopygium, detail of tergite IX, dorsal, C — hypopygium, tergite IX removed, sclerites hatched; left: ventral view with gonostylus removed, right: dorsal view. D – G — female genitalia, D — dorsal view, E — ventral view, left with gonapophysis removed, F — apodeme lobe, G — labia, H — vaginal opening.

FIGURE 7. Onconeura similispina n. sp. A – C — pupa, A — abdomen, dorsal view, B — sternite II, C — sternite VIII and anal lobe. D – I — larva, D — labrum, dorsal view, E — epipharyngeal region, ventral view, F — mentum, G — mandible, H — antenna, I — head capsule, dorsal view.