Onconeura undecimata, Andersen, Trond & Saether, Ole A., 2005

Andersen, Trond & Saether, Ole A., 2005, Onconeura, a new Neotropical orthoclad genus (Chironomidae, Orthocladiinae), Zootaxa 957, pp. 1-16 : 7-13

Onconeura undecimata new species

( Figs. 1 A–H, 2A–I, 3A–E)

Type material. Holotype male, CHILE: Region VI, Rio Mataquito west of Curico, 34°59.393'S, 71° 25.913W, 150 m a.s.l., 18.xi.1998, net, T. Andersen ( ZMBN Type no. 290). Paratypes: Allotype female, Region Metropolitana, Cajon del Maipo, Puente el Yeso, 33°47.127'S, 70°13.625'W, 1.842 m a.s.l., 16.ii.1999, net, T. Andersen; 3 males as for holotype; 7 mature male pupae, 5 mature female pupae, 89 pupal exuviae as for holotype, except driftnet; 14 males as for allotype; 8 males as for allotype, except 26.i.1996; 41 pupal exuviae, Region Metropolitana, Cajon del Maipo, Rio Vulcan at Los Valdes, 33°49.682'S, 70° 03.260W, 1.924 m a.s.l., 10.xi.1998, driftnet, T. Andersen; 17 pupal exuviae, Region VI, Rio Claro south of Molina, 35°09.171'S, 71°17.054'W, 212 m a.s.l., 18.xi.1998, driftnet, T. Andersen.

Diagnostic characters.The imagines are separable from those of O. semifimbriata by having 11 flagellomeres in the male, larger size, and darker coloration without distinctly ringed legs. The pupa is distinguished by having a reduced frontal seta, larger hooklets on tergal conjunctives, and anal lobe with 16–21 taeniae in the fringe, of which the anterior ones are short and spine­like and the preapical ones very long.

Etymology. From the Latin undecim, eleven, and the suffix ­ atus, equipped with, referring to the eleven flagellomeres.

Male imago (n = 10)

Total length 1.68–2.09, 2.88 mm. Wing length 0.90–1.18, 1.08 mm. Total length/wing length 1.69–1.87, 1.75. Wing length/length of profemur 2.71–2.98, 2.87. Thorax yellowish brown with blackish brown vittae, scutellum, postnotum, preepisternum, parts of anterior and median anepisternum II and part of epimeron II. Legs with pale trochanter and in most specimens slightly paler basiventral parts of femora and median parts of hind tibia and hind metatarsus.

Head ( Fig. 1 A). AR 0.60–0.71, 0.66. With 11 flagellomeres, ultimate flagellomere 195–263, 231 m long ( Fig. 1 C). Temporal setae 3–5, 4; including 1 inner vertical, 1–2, 2 outer verticals and 1–2, 1 postorbital. Clypeus with 10–16, 12 setae. Tentorium, stipes, and cibarial pump as in Fig. 1 B. Tentorium 116–158, 141 m long; 19–34, 26 m wide. Stipes 90–120, 110 m long; 26–38, 29 m wide. Palpomere lengths (in m): 26–41, 35; 34–45, 40; 60–75, 69; 83–109, 96; 109–141, 124. Third palpomere with 1 sensilla clavata.

Thorax ( Fig. 1 D). Antepronotum with 4–7, 6 setae. Dorsocentrals 12–19, 15; prealars 3, supraalar 1. Scutellum with 6–8, 7 setae.

Wing ( Fig. 1 F). VR 1.68–1.83, 1.75. Clavus 26–45, 35 µm wide; ending 128–169, 153 µm from arculus; with 0–1, 1 seta at apex.

Legs ( Fig. 1 E). Spur of front tibia 34–41, 38 m long; spurs of middle tibia 23–28, 25 and 13–19, 18 m long; of hind tibia 38–49, 45 and 17–23, 21 m long. Width at apex of front tibia 28–34, 31; of middle tibia 26–34, 31 m; of hind tibia 34–39, 37 m. Length (in m) and proportions of legs as in Table 1 .

Hypopygium ( Fig. 1 G–H). Tergite IX with 12–21, 17 minute setae; laterosternite IX with 2–3, 3 setae. Phallapodeme 49–56, 53 m long; transverse sternapodeme 30–53, 40 m long. Gonocoxite 109–143, 124 m long; superior volsella 8–15, 11 m wide, barely joined basally. Gonostylus 49–60, 56 m long; megaseta 9–11, 10 m long. HR 2.18–2.38, 2.24; HV 3.06–3.73, 3.38.

Female imago (n = 1, except when otherwise stated)

Total length 1.73 mm. Wing length 0.98 mm. Total length/wing length 1.77. Wing length/length of profemur 3.04. Coloration patterns as in male, but slightly more pale.

Head ( Fig. 2 A). AR 0.38–0.53, 0.46 (5). Flagellomere lengths (in m, n = 5): 38–45, 44; 26–36, 34; 30–36, 34; 34–36, 35; 38–64, 57. Temporal setae 4–5 (2), including 1–2 (2) inner verticals, 2–3 (2) outer verticals, and 1 (2) postorbital. Clypeus with 11–15, 13 (4) setae. Tentorium, stipes, and cibarial pump as in Fig. 2 B. Tentorium 101 m long, 15 m wide. Stipes 105 m long, 26 m wide. Palpomere lengths (in m): 34, 34, 60, 90, 128.

Thorax ( Fig. 2 C). Antepronotum with 5 setae. Dorsocentrals 11–15, 13 (4); prealars 3 (2), supraalar 1 (2). Scutellum with 4–6 (2) setae.

Wing ( Fig. 2 D). VR 1.74. Clavus 30 µm wide, ending 203 µm from arculus; with 10 setae.

Legs. Spur of front tibia 30 m long, spurs of middle tibia 23 long and lost, of hind tibia 41 and 15 m long. Width at apex of front tibia 30 m, of both middle and hind tibia 34 m. Length (in m) and proportions of legs as in Table 2 .

Abdomen. Number of setae on tergite I 8, on each of tergites II–VI 5–7, on VII 4, on VIII 5. Sternite I bare, sternites II–VII with or without 1–2 (3) stronger median seta and with 2 weak posterolateral setae, sternite VIII with 4–8, 7 (5) setae.

Genitalia (n = 6, Fig. 2 E–I). Gonocoxite with 4–6, 5 setae. Tergite IX with 11–15, 13 setae. Cercus 71–105, 82 m long. Seminal capsules 49–56, 54 m long; 38–45, 42 m wide. Notum 43–68, 56 m long.

Pupa (n = 9–10, except when otherwise stated) Total length 2.32–2.66, 2.47 mm.

Cephalothorax. Frontal setae ( Fig. 3 A) taeniate 19–30, 25 µm long; on 11–13, 12 µm high, 9–11, 10 µm wide tubercle. Longest precorneal seta 94–113, 98 µm long; other precorneals and lateral antepronotals less than 40 µm long. Median antepronotals 75–113, 94 µm (4) long; and 38–75, 55 µm (5) long. Anterior dorsocentral (Dc1) 56–75, 65 µm long; Dc2 34–60, 45 µm; Dc 3 11–38, 27 µm (8); Dc4 75­124, 104 (7) µm long and taeniate. Distances (in µm): Dc1­Dc 2 6­15, 10; Dc2­Dc3 124­176, 149, Dc3­Dc 4 4–30, 10. Wing sheath ( Fig. 3 B) with 5–7, 6 rows of pearls.

Abdomen ( Fig. 3 C–D). Shagreen and chaetotaxy as in generic diagnosis. Anal lobe ( Fig. 3 E) 91–221, 209 µm long; with 16–21, 18 taeniae; anterior 3–7, 4 taeniae spine­like, preapical taeniae very long, up to 188–345, 290 µm in length; anal lobe in addition with 1– 3, 2 apical spines. Anal macroseta 56–124, 75 µm long. Median seta 131–206, 171 µm long. Apex of genital sac of male 19–30, 22 µm (5) short of apex of anal lobe; female 49– 64, 55 µm short.

Ecology and distribution. The species has been collected from rivers in central Chile, from 150 meters up to nearly 2000 meters altitude in the western slopes of the Andes. The species can be very abundant in water channels along the larger rivers when they cross the central valley in Chile, and it has also been taken in smaller, faster flowing rivers with gravel and stony substrate in the foothills of the Andes.

Figures

FIGURE 1. Onconeura undecimata new species, male imago. A. head; B. tentorium, stipes, and cibarial pump; C. apex of antennae; D. thorax; E. trochanter of front leg; F. wing; G. tergite IX and dorsal aspect of left gonocoxite and gonostylus; H. hypopygium with anal point and tergite IX removed, left dorsal aspect, right ventral aspect.

FIGURE 2. Onconeura undecimata new species, female imago. A. head; B. tentorium, stipes, and cibarial pump; C. thorax; D. wing; E. genitalia, ventral view; F. genitalia, dorsal view; G. gonapophysis VIII; H. apodeme lobe; I. labium.

FIGURE 3. Onconeura undecimata new species, pupa. A. frontal apotome; B. wing sheath; C. tergites; D. sternites; E. detail of anal lobe.

Tables

TABLE 1. Lengths (in m, as range followed by the mean) and proportions of legs of Onconeura undecimata new species, male (n = 10).

	fe	ti	ta1	ta2	ta3	ta4	ta5	LR	BV	SV	BR
p1	331–406, 375	335–435, 399	255–312, 291	80–104, 95	47–66, 56	24–33, 29	33–38, 36	0.72–0.76, 0.73	4.72–5.11, 4.99	2.60–2.71, 2.66	1.6–2.2, 2.0
p2	406–501, 456	383–482, 442	250–302, 282	104–132, 109	57–76, 62	24–38, 28	33–43, 39	0.62–0.65, 0.64	4.49–4.98, 4.76	3.11–3.25, 3.18	1.8–2.2, 2.0
p3	331–416, 384	406–501, 458	269–326, 304	142–165, 152	57–76, 68	24–38, 27	38–47, 39	0.63–0.70, 0.67	3.80–4.55, 4.03	2.67–2.91, 2.77	2.0–3.5, 2.6

TABLE 2. Lengths (in m) and proportions of legs of Onconeura undecimata new species, female (n = 1).

fe	ti	ta1	ta2	ta3	ta4	ta5	LR	BV	SV	BR
p1 331	354	255	104	57	24	38	0.72	4.19	2.65	1.5
p2 416	392	255	80	47	24	38	0.64	5.65	3.19	1.8
p3 369	416	284	132	52	24	38	0.68	4.35	2.77	2.4