Madachironomus lakazana, Andersen, 2016

Andersen, Trond, 2016, MADACHIRONOMUS, A NEW GENUS OF TRIBE PSEUDOCHIRONOMINI (DIPTERA: CHIRONOMIDAE, CHIRONOMINAE) FROM MADAGASCAR Abstract, CHIRONOMUS Journal of Chironomidae Research 29 (29), pp. 15-26 : 18-23

Madachironomus lakazana sp. n.

http://zoobank.org/ C8B38DA0-E7ED-45FF-8322-BB82A3279AA5

Type material. Holotype male, Madagascar, Antananarivo province, Analamanga region, Anjozorobe district, Anjafy high plains, Betsiboka drainage, Lakazana River at Ankondondona , approx. 47°46’E 18°05’S, evening of 20.xi.1996, light trap, leg. LRSAE / ORSTOM ( ZSM) . Paratypes: 1 male, 2 females, same data as holotype ( ZMBN, ZSM) .

Etymology. Named after Lakazana River , Antananarivo province, Madagascar, where the species was collected. The name is to be regarded as a noun in apposition.

Diagnostic characters. See diagnostic characters for the genus. The female can be separated from the female of M. rongaronga sp. n. as it is larger, with a wing length of 4.16–4.18 mm compared to 3.11–3.58 mm in M. rongaronga , has a slightly lower antennal ratio (AR = 0.58–0.66 compared to AR = 0.70–0.81) and has distinctly more setae on segment X to each side of vagina (189–231 setae compared to 53–78 setae).

Description

Adult male (n = 2–3). Total length 9.16–9.45 mm. Wing length 4.12–4.16 mm. Total length / wing length 2.23–2.27. Wing length / length of profemur 2.32–2.35.

Coloration. Head, antennae and palpi brown. Thorax mostly brown with lateral mesonotal dark brown spot. Legs medium brown, foreleg with tibia and ta 2-5 brown, fore tibia with dark brown apex, fore ta 1 lighter brown with dark brown apex; mid- and hind legs with lighter brown tarsi. Wing membrane ( Fig. 8 ) translucent with brownish stain and some light shaded areas e.g. proximally and distally in cell c, along most of sc, proximal in r 4+5 and along Cu and proximal parts of M 3+4 and Cu 1; wing veins brownish, crossvein RM and radial fork darker brown. Abdominal segment 1 pale brown, abdominal segments 2–5 light brown with narrow anterior transverse brown band; segments 6–8 and hypopygium brown.

Antenna. AR 2.37–2.49. Terminal flagellomere 1503–1560 µm long.

Head ( Fig. 1 ). Temporal setae 22–25, briefly bi- to tri-serial near transition of eye to its dorsomedial extension, consisting of inseparably intergrading verticals and postorbitals. Clypeus with 62–68 setae. Tentorium, stipes and cibarial pump as in Figure 2 . Tentorium 277–312 µm long, 82–90 µm wide. Stipes 242–267 µm long, 21–25 µm wide. Palpomere lengths (in µm): 76–92, 112–128, 396– 412, 380–384, 640–651. Third palpomere with 2–3 sensilla clavata apically, longest 19–25 µm long.

Thorax ( Fig. 3 ). Antepronotum with 4–6 dorsal and 15–17 ventrolateral setae. Acrostichals apparently about 40; dorsocentrals 42–45, weak; prealars 3–11; supraalars 0–1. Scutellum with 48–52 setae in 2–3 irregular rows.

Wing ( Fig. 8 ). VR 0.98–0.99. C extension 72–109 µm long. Brachiolum with 2–3 setae; C extension with 4–6 non-marginal setae; R 4+5 with 0–1 seta apically; other veins bare. Wing membrane bare. Squama with 28–36 setae, partly bi- to tri-serial.

Legs ( Figs 4–5 ). Spur of fore tibia 80–89 µm long; spurs of mid tibia 100–115 µm and 103–121 µm long; spurs of hind tibia 105–121 µm and 113–127 µm long. Width at apex of fore tibia 111–113 µm; of mid tibia 127–131 µm; of hind tibia 135–139 µm. Mid ta 1 with about 15 sensilla chaetica in 3 rows in proximal 1/3, hind ta 1 with about 25 sensilla chaetica in 3 rows in proximal 1/3. Lengths and proportions of legs as in Table 1 .

Hypopygium ( Figs 6–7 ). Tergite IX with 13–17 setae along posterior margin to each side of base of anal point; laterosternite IX with 15–23 setae. Anal point tapering to tongue-shaped apex, 115–123 µm long, 66–75 µm wide at base, 29–35 µm wide subapically. Phallapodeme 316–324 µm long, including 88–96 µm long, 8–12 µm wide, curved oral projection. Transverse sternapodeme 120–128 µm long. Gonocoxite 380–404 µm long. Median volsella with main stem split medially in two digitiform projections; longest, caudal branch 72–80 µm long, 16–20 µm wide medially; shortest, oral branch 66–84 µm long; densely covered with subulate setae up to 66–85 µm in length. Superior volsella 92–108 µm long, including 34–38 µm long, hooked apical portion; with 1–2 strong, 28–30 µm long setae dorsolaterally, hooked apical portion with 3–6 medial to ventral setae. Inferior volsella broadly digitiform, 208–212 µm long, 80–100 µm wide at base, 48–56 µm wide medially, with 63–82 normal to strong setae. Gonostylus 328–344 µm long. HR 1.11–1.20. HV 2.74–2.80.

Adult female (n = 2). Total length 9.83–9.93 mm. Wing length 4.16–4.18 mm. Total length / wing length 2.36–2.39. Wing length / length of profemur 2.39–2.43.

Coloration. Generally distinctly darker than male. Head, antennae and palpi brown. Thorax mostly brown, lateral mesonotal dark spot less contrasting than in male, indistinct in some specimens. Legs medium brown; foreleg with tibia and ta 2–5 darker brown, fore tibia with dark brown apex, fore ta 1 lighter brown with dark brown apex; mid- and hind legs with lighter brown femoral apices and tarsi. Wing membrane translucent with brownish stain and some more darkly shaded areas, e.g. proximally and distally in cell c, along most of sc, proximally in r 1 and r 4+5, along Cu and proximal parts of M 3+4 and Cu 1; veins brown, crossvein RM and radial fork darker brown. Abdominal tergites and posterior sternites brown, anterior sternites light brown, anterior transverse segment bands indicated in some specimens; hypopygium medium brown.

Antenna ( Fig. 12 ). With 6 flagellomeres; AR = 0.58–0.66. Length and width of pedicel and flagellomeres 1–6 (in µm) as: 80–92 / 128–132, 100–104 / 56–60, 84–88 / 40–44, 92–104 / 40–44, 96–104 / 38–42, 88–92 / 36–40, 272–300 / 28–32. Flagellomeres 1–5 with ring of sensilla chaetica subapically, flagellomere 6 with sensilla chaetica in apical 2/3. Flagellomere 6 with 1–2 strong setae subapically, longest 118–148, 133 µm long.

Head ( Fig. 10 ). Temporal setae 22–24, briefly bito tri-serial near transition of eye to its dorsomedial extension, consisting of inseparably intergrading verticals and postorbitals. Clypeus with 105–112 setae. Tentorium, stipes and cibarial pump as in Figure 11 . Tentorium 304–316 µm long, 76–80 µm wide. Stipes 272–312 µm long, 24–28 µm wide. Palp segment lengths (in µm): 87–98, 108–114, 376–380, 380–388, 556–588. Third palpomere with 2–3 sensilla clavata apically, longest 21–25 µm long.

Thorax ( Fig. 13 ). Antepronotum with 6–9 dorsal and 14–15 ventrolateral setae. Acrostichals apparently about 40; dorsocentrals 36–41 weak, in 1–3 irregular rows; prealars 7–8. Scutellum with 44–48 setae in 2–3 rows.

Wing. VR 1.01–1.07. C extension about 60 µm long. Brachiolum with 2 setae, C extension with 2–5 non-marginal setae, R 1 with 8–12 setae in apical 1/3, R 4+5 with 2–5 seta apically, other veins bare. Wing membrane bare. Squama with 31–35 setae, partly bi- to triserial.

Table 2. Lengths (in µm) and proportions of legs of Madachironomus lakazana gen. n., sp. n., female (n = 2).

Legs. Spur of fore tibia 76–80 µm long, spurs of mid tibia 100–104 µm and 112–116 µm long, of hind tibia 100–108 µm and 116–120 µm long. Width at apex of fore tibia 116–124 µm, of mid tibia 128–136 µm, of hind tibia 136–144 µm. Mid ta 1 with about 50 sensilla chaetica in 2–3 rows in proximal 1/3, hind ta 1 with about 35 sensilla chaetica in 2–3 rows in proximal 1/3. Lengths and proportions of legs as in Table 2.

Genitalia ( Figs 14–19 ). Segment X with 189–231 setae to each side of vagina. Seminal capsule ovoid, 176–184 μm long, not including 18–20 μm long neck, 120–132 μm wide. Notum 204–228 μm long. Dorsomesal lobe 218–224 μm long from base of vagina to apex. Gonocoxite IX with 28–30 setae. Tergite IX with 31–37 setae. Cercus 284– 292 μm long.

Larva and pupa. Unknown.

Figures

Figures 8-9. Madachironomus gen. n., wings. 8) M. lakazana sp. n., male; 9) M. rongaronga sp. n., female (photo Torbjørn Ekrem).

Figures 1-5. Madachironomus lakazana gen. n., sp. n., male. 1) head; 2) tentorium, stipes and cibarial pump; 3) thorax; 4) comb of foreleg; 5) combs of hind leg.

Figures 6-7. Madachironomus lakazana gen. n., sp. n., male. 6) hypopygium, dorsal view; 7) hypopygium with anal point and tergite IX removed, dorsal aspect to the left and ventral aspect to the right.

Figures 10-13. Madachironomus lakazana gen. n., sp. n., female. 10) head; 11) tentorium, stipes and cibarial pump; 12) antenna; 13) thorax.

Figures 14-19. Madachironomus lakazana gen. n., sp. n., female. 14) genitalia, ventral view; 15) tergite IX; 16) dor- somesal lobe; 17) ventrolateral lobe; 18) apodeme lobe; 19) labium.

Tables

Table 2. Lengths (in µm) and proportions of legs of Madachironomus lakazana gen. n., sp. n., female (n = 2). fe ti ta1 ta2 ta3 ta4 p1 1710–1751 2348–2410 1710–1812 700–721 618–639 494–515 p2 2245–2266 2554–2698 948–1009 515–556 453–474 288–330 p3 2369–2390 2760–2946 1195–1257 597–700 556–618 350–371 ta 5 LR BV SV BR p1 226–247 0.728–0.752 2.800–2.843 2.295–2.373 1.733–1.750 p2 144–165 0.371–0.374 3.905–4.118 4.898–5.087 1.750–1.888 p3 144–165 0.427–0.433 3.556–3.837 4.293–4.246 1.600–1.700

p 1 p 2 p 3	fe 1710–1751 2245–2266 2369–2390	ti 2348–2410 2554–2698 2760–2946	ta1 1710–1812 948–1009 1195–1257	ta2 700–721 515–556 597–700	ta3 618–639 453–474 556–618	ta4 494–515 288–330 350–371
p 1 p 2 p 3	ta 5 226–247 144–165 144–165	LR BV 0.728–0.752 2.800–2.843 0.371–0.374 3.905–4.118 0.427–0.433 3.556–3.837			SV 2.295–2.373 4.898–5.087 4.293–4.246	BR 1.733–1.750 1.750–1.888 1.600–1.700