Stenochironomus figueiredoensis, Dantas, Galileu P. S., Hamada, Neusa & Mendes, Humberto F., 2016

Dantas, Galileu P. S., Hamada, Neusa & Mendes, Humberto F., 2016, Contribution to the knowledge of Stenochironomus Kieffer (Diptera, Chironomidae) from Brazil: seven new species and description of females and immatures of some previously known species, Zootaxa 4117 (1), pp. 1-47 : 12-16

Stenochironomus figueiredoensis new species

( Figs. 9–11 )

Type material. Holotype male, BRAZIL: Amazonas state, Presidente Figueiredo, AM 240, KM 61, 01º59'32.7"S, 59º31'20.1"W, 22.ii.2009, in decayed leaves, G.P.S. Dantas ( INPA). Paratypes: 1 male with pupal exuviae, same locality as holotype collected 17.ii.2009; 1 male, same as holotype collected 20.ii.2009 ( MZUSP); 1 male, same as holotype collected KM 24, 02º01'13,2"S, 59º49'29,1"W, 25.ii.2009; 1 male with pupal exuviae, same as holotype collected KM 24, 02º01'13.2"S, 59º49'29.1"W, 02.iii.2009.

Diagnostic characters. Male: thorax with elliptic patch on posterior margin of lateral vitta; anal point straight and narrow along its entire length; genitalia light-brown with transversal light band near posterior margin; gonostylus short and slightly curved; phalapodeme curved anteriorly; tergite IX with strong pre-apical constriction, caudal apex truncated. Pupa: frontal apotome not elongated; S V with 3–4 LS setae; T VII and T VIII with shagreen; anal lobe with a fringe of about 50 filaments.

Etymology. the name of species refers to the type locality, the municipality of Presidente Figueiredo.

Male (n = 5, except when otherwise stated). Total length 2.81–3.51, 3.19 mm. Wing length 1.72–1.91, 1.78 mm. Total length/ wing length 1.62–2.04, 1.85. Wing length/ length of profemur 1.29–1.32, 1.31.

General coloration greenish. Eyes metallic green when alive or in alcohol. Thorax: scutum light brown; scutellum and postnotum brown; lateral vitta with elliptical brown patch on posterior margin; anterior margin of preepisternum light brown. Legs: front femur yellowish with two dark brown areas, one on half and one on apex; tibia yellowish on mid region, brown on extremities; ta1 yellowish with light-brown apex; ta2–5 light brown. Mid and hind legs yellowish with brownish apex of the femur and base of the tibia. Abdomen: posterior ⅓ of T II–III brown; posterior margin of T IV–V light brown. Hypopygium: light brown with a clear transversal band near posterior margin of T IX.

Head ( Fig. 9 A). AR 1.39–1.47, 1.43. Thirteenth flagellomerum 610–665, 602 µm long. Temporal setae 11–12, 11(in groups). Clypeus with 23–30, 25 setae. Tentorium, stipes and cibarial pump as in Figure 9 A. Tentorium 151– 155, 153 µm long; 30–36, 32 µm wide at sieve pore; 15–18, 16 µm wide at posterior tentorial pit. Stipes 140 (1) µm long; 7 (1) µm wide. Palpomere lengths (1–5 in µm): 47–60, 56; 56–62, 59; 181–186, 185; 120–128, 125; 243– 246, 243.

Thorax ( Fig. 9 B). Acrostichals 6–9, 7, distributed until anterior margin of scutum; dorsocentrals 8–10, 9 in a single row; prealars 3–4, 3 in a single row. Scutellum with 13–15, 14 setae in a single row. Anterior edge of scutum angled in lateral aspect.

Wing ( Fig. 9 C). VR 1.11–1.15, 1.13. Brachiolum with 2 setae, with about 24 sensillae campaniformia. R with 27–32, 29 setae; R1 with 25–29, 28 setae; R4+5 with 40–51, 45 setae; M with 3–8, 5 setae; RM with 1–2, 2 setae; remaining veins bare . Squama with 3 setae.

Legs. Scale of front tibia 38–48, 42 µm long; spurs of middle tibia 32–39, 35 µm and 36–41, 39 µm long; spurs of hind tibia 35–41, 36 µm and 37–44, 39 µm long. Apex of fore tibia 56–62, 60 µm wide, of mid tibia 55–62, 59 µm wide, of hind tibia 59–70, 64 µm wide. Lengths (in µm) and proportions of legs as in Table 4.

fe ti ta1 ta2 ta3 ta4

p1 1305–1483, 1358 983–1138, 1033 1484–1617, 1524 718–804, 743 571–656, 598 557–607, 572 p2 1018–1145, 1062 905–1002, 928 599–641, 616 287–318, 298 232–261, 239 165–174, 169 p3 1215–1354, 1250 1123–1242, 1164 832–893, 846 451–482, 464 372–428, 394 223–240, 227

ta5 LR BV SV BR

p1 218–242, 233 1.42–1.55, 1.48 1.80–1.84, 1.83 1.54–1.62, 1.57 3.8–4.3, 4.0 p2 80–94, 86 0.64–0.68, 0.66 3.26–3.35, 3.30 3.13–3.35, 2.23 2.4–2.8, 2.6 p3 96–104, 99 0.71–0.74, 0.73 2.68–2.80, 2.75 2.78–2.91, 2.85 3.0–4.4, 3.9 Hypopygium ( Figs. 10 A, 10B, 10C). Anal point narrow, straight ( Fig. 10 A) 64–68, 65 µm long; 10–12, 11 µm wide at base; 7 µm wide at midpoint; 9 µm wide at apex. Tergite IX with 34–36, 35 setae, caudal apex truncated in dorsal aspect, with accentuated pre-apical constrictions. Laterosternite IX with 4 setae. Phallapodeme anteriorly curved, 100–114, 107 µm long; transverse sternapodeme 31–41, 38 µm long. Gonocoxite 147–167, 156 µm long; inferior volsella 139–170, 158 µm long, with 4–6, 5 setae, restricted to anterior region, apical setae stout; superior volsella 30–31, 30 µm long, 21–23, 22 µm wide at base, with long 4 setae. Gonostylus slightly curved, 120–125, 122 µm long. HR 1.24–1.34, 1.29. HV 2.48–2.93, 2.75.

Pupa (n = 2 except when otherwise stated). Total length 4.40–4.92 mm.

Coloration: cephalothorax light brownish and abdomen transparent.

Cephalothorax ( Figs. 11 A, 11B). Frontal apotome not elongated ( Fig. 11 A). Precorneal setae 127–167 µm long. Dorsocentrals (Dc) 24 µm long. Distance between Dc1 and Dc2 4–6 µm; between Dc2 and Dc3 161–197 µm; between Dc3 and Dc4 4–6 µm. Median suture granulose. A ventral tubercle close to wing sheath base; a laterodorsal tubercle anterior to Dc1 ( Fig. 11 B).

Abdomen ( Figs. 11 C, 11D). T I bare ; T II–III with large field of shagreen; T IV with large field of shagreen, being thicker near the anterior and posterior margins, posterior half of paratergites with shagreen; T V with large field of shagreen, being thicker near to posterior margin; T VI with fine shagreen on anterior region and shagreen thicker on posterior region; on central region shagreen is restricted to median area; T VII with anterior pair of shagreen patches and a small field of shagreen near the posterior margin; T VIII and anal segment with anterior pair of shagreen patches. TII with posterior row of hooklets not extending to lateral margin of tergite, divided medially into two groups by 32 (1) µm. Abdominal setation: S I without L setae; S II–IV with 3 L setae; S V with 3–4 LS setae; S VI–VII with 4 LS setae; S VIII with 5 LS setae. Pedes spurii B absent on S II. Spur on S VIII with 3 brownish teeth, median tooth larger than another ( Fig. 11 E), 57–58 µm long. Genital sac 267–289 µm long, overreaching the posterior margin of the anal lobe by 14 (1) µm; anal lobe rounded at apex, 266–287 µm long, with fringe of about 50 filaments.

Female and larva unknown.

Systematic remarks. The male imago of S. figueiredoensis sp. nov. would key to couplet 20 ( S. impendens / S. aculeatus ) in Borkent (1984) and coloration of abdomen easily distinguish it from these species.

Notes on biology of the species. The specimens were reared from leaves collected retained in submerged branches and roots, both in areas with strong water flow in large rivers, as in small streams with about 20 cm wide.

Figures

FIGURE 9. Stenochironomus figueiredoensis sp. nov., adult male. A, head. B, thorax, in lateral view. C, wing.

FIGURE 10. Stenochironomus figueiredoensis sp. nov., adult male. A, hypopygium dorsal view. B, hypopygium with tergite IX removed, left dorsal view, right ventral view. C, anal point, in lateral aspect.

FIGURE 11. Stenochironomus figueiredoensis sp. nov., pupae. A, frontal apotome. B, thorax, in lateral view. C, tergites I – IV. D, tergites V – IX. E, spur on S VIII.