Corynoneura septadentata, Wiedenbrug, Sofia & Trivinho-Strixino, Susana, 2011

Wiedenbrug, Sofia & Trivinho-Strixino, Susana, 2011, New species of the genus Corynoneura Winnertz (Diptera, Chironomidae) from Brazil, Zootaxa 2822, pp. 1-40 : 21-26

Corynoneura septadentata sp. n.

( Figs 13–15 )

Corynoneura -Gruppe spec. 2: Wiedenbrug 2000: 99

Type material. Holotype male with pupal and larval exuviae, BRAZIL, SP, São Paulo, Parque Estadual do Jaraguá, stream near playground, 14.iv.2007, S. Wiedenbrug. Paratypes: allotype female with pupal and larval exuviae, same data as holotype; two males with pupal and larval exuviae, same data as holotype; one male with pupal and larval exuviae same data as holotype but 09.ix.2007.

Additional material. One pharate male with pupal exuviae, RJ, Nova Friburgo, Rio Boa Vista, 28.viii.1995, E. J. Fittkau et al.; one pupal exuviae, MG, Bocaína de Minas, 9 Km from Vila de Maringá, Rio Santa Clara, Cachoeira do Santuário, 25.i.2008, S. Wiedenbrug; 6 pupal exuviae, SP, Jundiaí, Serra do Japí, 23°14´30´´S, 46° 57´16´´W, 18.xii.2007, S. Wiedenbrug.

Diagnostic characters. The adult males are separable from other species by the antenna with 11 flagellomeres, AR 0.2, eyes bare, attachment of the phallapodeme caudal on the sternapodeme, phallapodeme posterior margin sclerotized and strongly curved to anterior, the presence of a small aedeagal lobe and the short gonostylus. Adult females are distinguished from other species except C. sertaodaquina and C. sp. sexadentata by the labia funnel shaped, one large seminal capsule sclerotized, the second less sclerotized difficult to see, gonapophysis posteromedian margin straight. The pupae are separable from other species except C. sp. sexadentata by having tergites IV and V with spines of shagreen increasing in size posteriorly, sternite II without shagreen, 4 LS-setae on segments III–VIII, anal lobe rectangular, more than a half of the anal lobe lateral margin with short and thin setae and posterior margin with fringe. The larvae can be recognized by the mentum with 7 median teeth, antenna slightly smaller as post–mentum, head not elongated (post–mentum length/head length less than 1), frontal apotome about 170 µm long, modified abdominal seta split apically.

Etymology. From Latin, Septa meaning seven and dentatus meaning provided with teeth, referring to the seven median larval teeth on the mentum.

Description. Male (n = 1–3)

Total length [0.73]– 0.80 mm. Wing length [0.53]– 0.57 mm. Total length/wing length [1.39]–1.41 Wing length/ length of profemur [3.23] 3.10–3.54.

Color. Thorax brownish; legs whitish; tergites I–II white, III–IV with brownish posteromedian area, V–IX brownish; sternites V–VII brownish.

Head ( Fig 13 A). AR = [0.22]–0.24. Antenna with [11] flagellomeres, ultimate flagellomere [55]–65 µm long; one sensilla chaetica at first, second and last flagellomeres; flagellomeres, except the first and last with more than one row of setae each ( Fig.13 B). Temporal setae absent. Clypeus [28]–38 µm long, with 6–7 setae. Tentorium [93]–110 µm long; [10] µm wide. Palpomere lengths (in µm): [10], [10], [15], 15–[18], [35]–43. Third palpomere with one sensilla clavata. Eyes bare.

Thorax ( Fig.13 C). Antepronotum with 1 seta. Dorsocentrals 3, prealars 2. Scutellars 2. Antepronotal lobes dorsally tapering.

Wing ( Fig. 13 D). VR 3.30–[3.41]. Clavus [25]–30 µm wide, ending [125]–130 µm from arculus. Clavus/wing length 0.23–[0.24]. Anal lobe absent.

Legs. Spur of front tibia [17]–20 µm long; spur of middle tibia [13]–15 µm long; spurs of hind tibia [35] µm long, 2nd spur s-shaped. Fore and mid tibial scales [5] µm long; hind tibial scale [33]–43 µm long. Width of apex of front tibia [15] µm; of middle tibia [13]–15 µm; of hind tibia 28–[33] µm. Leg measurements (in µm) and ratios as in Table 9.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 165–183 195–215 92–100 57–62 27–33 12 –15 22 0.47–0.48 3.69–3.89 3.89–3.97 2.66–3.33 p2 245–275 200–225 140–148 57–70 30–35 15–18 25 0.64–0.70 4.37–4.58 3.17–3.44 2.50–4.33 P3 190–200 175–207 110–113 57– 65 25–27 12–15 20–25 0.56–0.59 3.84–4.27 3.40–3.56 2.75–3.00 Abdomen. One seta on TVIII.

Hypopygium ( Figs 13 E–F) Tergite IX with 4 small setae. Laterosternite IX with 1 seta. Aedeagal lobe small, triangular. Superior volsella low, with short setae directed to median. Inferior volsella prominent with longer microtrichia directed medially. Phallapodeme, posterior margin sclerotized strongly curved to anterior 17 – 22 µm long; transverse sternapodeme [7]–12 µm long. Gonocoxite [45] µm long. Gonostylus oval, not tapering apically, 10–[17] µm long; megaseta [2]–5 µm long. HR [2.57]–4.50; HV [4.17]–5.33.

Female (n = 1)

Total length 0.86 mm. Wing length 0.47 mm. Total length/wing length 1.84. Wing length/length of profemur 3.45.

Color. Thorax and abdomen light brown, legs whitish.

Head. AR 0.49. Antenna with 5 flagellomeres, apical flagellomere 47 µm long; one sensilla chaetica on flagellomeres 2–4 and two on flagellomeres 5. Temporal setae absent. Clypeus 32 µm long, with 8 setae. Tentorium 65 µm long, 2 µm wide. Palpomere lengths (in µm): 5, 10, 12, 15, 35. Sensilla clavata not possible to see. Eyes bare.

Thorax. Dorsocentrals and prealars not possible to see. Scutellum with 2 setae. Antepronotal lobes dorsally tapering.

Wing ( Fig. 14 A). VR 2.04. Clavus 25 µm wide, ending 207 µm from arculus. Clavus/wing length 0.44.

Legs. Spur of front tibia 7 µm long; spur of middle tibia 7 µm long; spurs of hind tibia 30–40 µm long, second spur small s-shaped. Hind tibial scale 33 µm long. Width of apex of front tibia 15 µm, of middle tibia 15 µm, of hind tibia 30 µm. Leg measurements (in µm) and ratios as in Table 10.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 138 172 82 47 22 12 22 0.48 3.74 3.76 2.67 p2 215 195 117 50 25 12 22 0.60 4.79 3.49 2.50 p3 175 162 87 50 20 12 25 0.53 3.95 3.86 2.75 Abdomen. One seta on TVIII.

Genitalia ( Figs 14 B–C). Gonocoxite IX with 1 seta. Tergite IX with 4 setae, two stronger, dorsal and two smaller, ventral. Seminal capsule 37 µm and spermathecal duct long with a loop, second seminal capsule less sclerotized apparently absent with spermathecal duct shorter and straight, both ducts join together shortly before seminal eminence, which has sclerotized outer borders. Notum 30 µm long. Membrane median curved to posterior, less sclerotized on the link of both sides. Apodeme lobe anterior margin in the same shape as membrane, apically pointed, posterior margin difficult to define. Coxosternapodeme apparently without lateral lamellae, strongly curved with one end at the roof of copulatory bursa, last semicircle-shaped. Labia separated, membranous, bare, triangle-shaped, ventrally longer than copulatory bursa posterior margin, apically funnel shaped, median apical margin with small curves building the accessory gonopore(?), labia dorsally with straight median margin, building the funnel posterior to the posterior margin of the copulatory burse. Gonocoxapodeme straight, gonapophyses without lobes. Post-genital plate with a straight posterior margin and few microtrichia. Cercus 30 µm long.

Pupa (n = 1–2)

Total length 1.1–1.2 mm.

Cephalothorax. Frontal apotome not granulated ( Fig. 15 A). Frontal setae 30–62 µm long. Postorbitals 40–100 µm and 25–27 µm; Longest median antepronotals 55 µm and 30 µm. Lateral antepronotals 50 µm. Precorneal setae Pc1 20 µm long. Dorsocentrals Dc1 32–42 µm long; Dc 2 27–30 µm long; Dc 3 20–27 µm long; Dc 4 27–35 µm long. Distance between Dc1 and Dc2 75 µm; Dc2 and Dc3 37–47 µm; Dc3 and Dc 4 27–32 µm. Dc1 displaced ventrally. Wing sheath with two to three rows of pearls ( Figs 15 B–C).

Abdomen ( Figs 15 D–G). Tergite I and sternite I–III without shagreen. Tergite II with few shagreen points. Tergites III–VIII with fine shagreen grading to a row of slightly stronger points posteriorly ( Fig. 15 E–G). Tergite IX with shagreen. Sternites VI–VIII with very fine shagreen. Sternite VIII on female bare. Conjunctive TII/III with 8 hooklets; TIII/IV with 12–14 hooklets and about 6 spinules; TIV/V with 12–15 hooklets; TV/VI with 2–4 hooklets; TVI/VII without hooklets, with a row of small spinules; SIV/V with 8 hooklets; SV/VI with 6–8 hooklets; SVI/VII with 11 hooklets; SVII/VIII with 7–11 hooklets.

Segment I with 3 D-setae, 1 L-setae, without V-setae; segment II 3 D, 3 L and 3V-setae; segment III 3 D, 3 V and 4 short and taeniate L-setae; segments IV-VII with 4 D, 3V and 4 taeniate L-setae; segment VIII with 2 D, 1 V and 4 taeniate L-setae.

Anal lobe ( Fig. 15 F) rectangular 92–100 µm long (Fig.). Anal lobe fringe with 10–11 lateral fine and shorter setae and posterior 16–17 taeniate setae 250–330 µm long with about 3 thinner and shorter median setae; 3 macrosetae taeniate, 82 µm long; inner setae taeniate.

Larva (n = 2).

Head ( Fig 15 H). Head capsule integument smooth. Frontal apotome 170–175 µm long, head width 125–145 µm. Postmentum 120–125 µm. Postmentum/head width 0.83–1.00. SI simple ( Fig. 15 I). Premandible with an outer lateral lamellae with a brush. Mentum with seven median teeth and four adjacent teeth ( Fig. 15 K). Distance between setae submenti 40–43 µm. Mandible length 40–43 µm with outer sclerotized protuberance. Antennae ( Fig. 15 J). AR 1.2–1.3. Length of segment I 62 µm, II 22–25 µm, III 22 µm, IV 2 µm; basal segment width 10 µm; antennal blade 17 µm long; ring organ at 12 µm from the base of first antennal segment. Third antennal segment with wall from one side not sclerotized. Antennal segments two and three brown.

Abdomen. At least 3 anterior segments with a pair of ventral modified setae, pectinate ( Fig. 15 L). Anal setae length 87 µm. Subbasal seta on posterior parapod simple, 52–55µm long, with a serrate side ( Fig. 15 M).

Remarks. Larvae from Corynoneura septadentata were collected from litter near the water surface of a small shallow stream. The species has been found in low order streams in the mountainous regions from Minas Gerais, Rio de Janeiro, São Paulo and Rio Grande do Sul States.

See also the remarks of Corynoneura sertaodaquina .

Figures

FIGURE 13. Corynoneura septadentata sp. n., male. A—head, dorsal view, left, sclerites hatched. B—terminal flagellomeres. C—thorax. D—wing. E and F—hypopygium. E—tergite IX; left: dorsal view, right: ventral view. F—tergite IX removed, sclerites hatched; right: dorsal view, left: ventral view.

FIGURE 14. Corynoneura septadentata sp. n., female. A—wing. B—dorsal view of genitalia with labia, right: dorsal view of labia, left: ventral view of labia. C—ventral view of genitalia; left: gonapophysis removed.

FIGURE 15. Corynoneura septadentata sp. n., immatures. A – G—pupa. A—frontal apotome. B—thorax, lateral view. Cdetail of wing sheath margin. D—abdomen, tergites I – VII. E—Tergite IV. F—tergite VIII and anal lobe. G—detail of posterior shagreen of tergite IV. H – M—larva. H—dorsal view of the head and antenna. I—Dorsal view of labrum. J—antenna. K—mentum. L—abdominal setae. M—sub-basal seta of posterior parapod.