Stenochironomus triannulatus Borkent, 1984

Reis, Emiliano De Angelis, Filho, Arlindo Serpa & Ferreira-Keppler, Ruth L., 2013, Two new species and records of Stenochironomus Kieffer from Brazilian Amazon region, with description of immature stages (Diptera: Chironomidae), Zootaxa 3710 (5), pp. 449-466 : 461-464

Stenochironomus triannulatus Borkent, 1984

Figs 9–10

Stenochironomus triannulatus Borkent, 1984: 113 ; Spies & Reiss 1996: 73.

Material examined. BRAZIL, Amazonas State, Manaus, Bairro Tarumã, Sítio do Raul, 03º 01’22,0”S, 60º 04’47,0’’W, 14.VII.11, collected in submerged leaves, 2 males with pupal and larval exuviae, leg. E.D. De- Angelis-Reis (INPA, slide-mounted in Euparal); BRAZIL, Roraima State, Alto Alegre, road access to Estação Ecológica de Maracá, mark #2, 03 º 14’33,2’’N, 61º 15’18,3’’W, 13–20. IX.11, 1 male with pupal and larval exuviae, leg. E.D. De-Angelis-Reis; BRAZIL, Roraima State, Cantá, Ramal da RR 44, Vila Serra Grande 1, mark #1, 02 º 32’08’’N, 60º 47’53,2’’W, 13–20.IX. 11,1 male with pupal and larval exuviae, leg. E.D. De-Angelis-Reis; BRAZIL, Amazonas State, Presidente Figueiredo, BR 174, Km 107, Hotel Fazenda Marupiara, 02º 03’38,6”S, 60º 06’60’’W, 19.X.10, 2 males with pupal and larval exuviae, leg. E.D. De-Angelis Reis.

Diagnostic characters. The adult male can be separated from all other Stenochironomus species by the following combination of characters: preepisternum with a dark brown stripe; tergites II–IV: pigmentation along the lateral and posterior margin; femur of fore leg with three dark stripes. The pupa is distinct for having an elongated frontal apotome, rounded frontal warts and developed wing tubercle.

Pupa (n = 6, exuviae, except when counted differently)

Total length 4.81–6.54; 5.41 mm.

Colour: light brown cephalothorax and abdomen.

Cephalothorax. Frontal apotome: elongated with rounded frontal warts ( Fig. 9 A), present wing tubercle. Precorneal setae 2; 92–115 (5); 112 Μm long. Dorsocentrals (Dc) 31–140; 69 µm long. Distance between Dc1 and Dc2 1–3; 1.5 µm; Dc2 and Dc3 227–298; 230 µm; Dc3 and Dc4 1–2; 1.5 µm; median suture granulose ( Fig. 9 C). Tubercle above the base of wing sheath.

Abdomen ( Fig. 9 B). TI: median, field of shagreen; TII–IV: median, large field of shagreen; TV: field of shagreen restricted to median regions; TVI: field of shagreen restricted to two patches on anterior and posterior regions; TVII–VIII: bare; anal segment with an anterior pair of rounded shagreen patches. TII has a posterior row of hooklets in the median region and which is divided medially in two groups of 95–124; 114 µm and 91–124; 107 µm, by a distance of 34–48; 36 µm. Abdominal setation: SI: with no L setae; SII–IV: 3 L setae; SV–VII: 4 LS setae; SVIII: 5 LS setae. Spur on SVIII: 5 brownish teeth, and two major outermost teeth ( Fig. 9 D). Genital sac 231–289 (3) Μm long, overreaching posterior margin of anal lobe by 44–77 (2) Μm; apex of anal lobe rounded, with a fringe of 33–40; 37 (4) filaments.

Fourth-instar larva (n = 6 exuviae, except when counted differently).

Cephalic capsule 0.39–0.58; 0.27 mm long.

Head. Antenna ( Fig. 10 A); lengths of antennal segments (in Μm): 53–78; 64, 22–32; 24, 9–13; 11, 10–13; 11, 5–7; 6 (5). Antennal blade 13–22; 16 (5) Μm long. Labrum. Labral lamella with two groups of comb-like arranged spicules, spicules of pecten epipharyngis composed of linear forms ( Fig. 10 E). SI simple and robust with 11–19; 15 Μm long; SII branched with 14–22; 17 Μm long; SIII branched with 13–22; 17 Μm long. Premandible 44–68; 57 Μm long. Mandible ( Fig. 10 B) 126–150; 137 (5) Μm long, with 4 inner teeth. Mentum ( Fig. 10 C) 98–134; 115 Μm wide and convex, with 10 blackish teeth; micropore is located posteriorly to submenti setae; paralabial plate with strong concavity near to mentum and no striae. Base of dorsolateral strip originated from the near base of dorsomedian strip. Labiohypopharynx ( Fig. 10 D) with ligular rounded lobes, large narrow cleft between lobes, nearly parallelsided to U-shaped structure.

Remarks. Stenochironomus triannulatus was, so far, only known to Brazil in the Amazonas State. In this paper we recorded this species for the first time in the Roraima State. S. triannulatus and S. bacrionis Borkent, 1984 are similar in having a wing tubercle and the same shape of the anal spur of pupa.

Stenochironomus bacrionis Borkent, 1984

Stenochironomus bacrionis Borkent, 1984: 105 ; Spies & Reiss 1996: 73.

Material examined. BRAZIL, Amazonas State, Manaus, Presidente Figueiredo, BR 174, Km 107, Hotel fazenda Marupiara, 02º 03’38,6”S, 60º 06’60’’W, 19.X.10, collected in a submerged leaves, 1 male with pupal and larval exuviae, leg. E.D. De-Angelis-Reis (INPA, slide-mounted in Euparal); BRAZIL, Amazonas State, Presidente Figueiredo, AM 240, Igarapé do Seu José, 02° 01'13,2"S, 59° 49'29,1"W, 8.IX.11, 1 male with pupal exuviae, leg. E.D. De-Angelis-Reis.

Remarks. Stenochironomus bacrionis were obtained from submerged mined leaves in small rivers with poor water flow. This species was only known to Ecuador and Brazil in the Pará State. Now we record it for the first time in the Amazonas State.

Stenochironomus jubatus Borkent, 1984

Stenochironomus jubatus Borkent, 1984: 116 ; Spies & Reiss 1996: 73.

Material examined. BRAZIL, Roraima State, Cantá, Ramal da RR 44, Igarapé Floresta 5, 02 ° 31'08"N, 60° 46'06"W, 2–6.VIII.10, collected in submerged wooden trunk, 1 male, leg. E.D. De-Angelis-Reis (INPA, slidemounted in Euparal).

Remarks. The larvae of S. jubatus Borkent, 1984 , were found just beneath the bark of woody debris in small streams with sandy bottom and with poor water flow. This species was just known only from Brazil in the Amazonas State. Herein we record this species for the first time in the Roraima State.

Figures

FIGURE 9. Stenochironomus triannulatus Borkent, 1984, pupa. A—frontal apotome, B—abdomen: tergites I – IX, Ccephalothorax, D—spur on T VIII. E—basal ring of thoracic horn.

FIGURE 10. Stenochironomus triannulatus Borkent, 1984, larva. A—antenna, B—mandible, C—mentum and paralabial plate, D—labiohypopharynx, D—labrum.