Telmatogeton goughi, Saether, Ole A. & Andersen, Trond, 2011

Saether, Ole A. & Andersen, Trond, 2011, Chironomidae from Gough, Nightingale and Tristan da Cunha islands, Zootaxa 2915, pp. 1-19 : 4-8

Telmatogeton goughi sp. n.

( Figs 2–10 )

Telmatogeton sanctipauli Freeman (1962: 79) : Holdgate (1965: 396); Barber-James (2007: 29); not Schiner, 1868: 25 sensu Wirth (1947: 182).

Telmatogeton sp. near sanctipauli Jones et al. (2003: 249) ; Gaston et al. (2003: 1096).

Type material. Holotype male, GOUGH ISLAND: Site TD1 at Tumbledown, 40o20'999"S, 0 9o 53'256"W, boulder beach, 5 m a.s.l., 2000, Malaise trap, C. Hänel & A.G. Jones ( ZMBN). Paratypes: 1 male, 3 females as holotype; 1 male, 5 females, Soph. E, on the east side of Sophora Glen, 40o18'954"S, 0 9o 54'149"W, supralittoral, 5 m a.s.l., 16.ii.2001, sweeping, L. Mabulu & P. Skepe ( BMNH, TCD, ZMBN).

Etymology. Named after Gough Island.

Diagnostic characters. The species differs from other known species by having tarsal claws bifid and asymmetrical, pectinate arm and simple arm subequal in length on one claw, about half as long on other claw; flagellomeres with setae; mid- and hind-trochanters each with knob-like projection which is about twice as long as broad.

Description. Male (n = 7, except when otherwise stated). Total length 4.81–6.24, 5.51 mm. Wing length 3.59– 4.27, 3.95 mm. Total length / wing length 1.29–1.53, 1.39. Wing length / length of profemur 2.07–2.30, 2.13.

Coloration. General dark brown with vittae and markings blackish. Legs and abdomen brown with apophyses and hypopygium darker. Wings slightly brown.

Head. Pedicel 109–146, 126 µm long; 98–120, 107 µm wide; with 30–50, 41 setae. Six flagellomeres. AR 0.45–0.63, 0.53. Lengths (in µm) of flagellomeres: 90–131, 115; 41–49, 44; 41–49, 44; 28–49, 40; 38–49, 44; 139– 169, 148. Flagellomeres 1 and 2 each with 1–3, 2 setae; third flagellomere with 0–3, 2 setae; fourth with 0–2, 1 seta; fifth with 1–2, 1 seta; sixth flagellomere with 2–4, 3 setae; no distinct sensilla. Temporal setae 28–35, 30 including 6–9, 7 very strong postorbitals; 6–8, 7 outer verticals; 15–18, 17 inner verticals; and 6–10, 8 very strong orbitals. Cibarial pump as in Figure 2 . Clypeus with 27–98, 65 strong setae. Palpomere lengths (in µm): 34–56, 43; 49–94, 71; 101–150, 124. First palpomere very weak and indistinct.

Thorax. Antepronotum with 6–9, 8 (6) very weak setae. Dorsocentrals 4–9, 6, weak; prealars 7–12, 10; supraalar setae absent; prescutellar setae absent. Scutellum with 22–33, 26 setae of variable strength.

Wing ( Fig. 3 ). VR 0.95–1.00, 0.98. Costal extension indistinct, 45–86, 59 µm long. Brachiolum with 4–9, 7 setae; R with 17–34, 25; R1 with 6–9, 7; R4+5 with 19–26, 23 setae; other veins bare. Squama with 8–20, 14 weak setae.

Legs. Mid trochanter with 143–217, 179 µm long; 75–105, 87 µm wide projection. Hind trochanter with 142– 188, 168 µm long; 45–64, 52 µm wide projection. Spur of fore tibia apparently absent in two specimens, 56–71, 65 µm long in other five; spur of mid tibia 68–71, 69 µm long; spurs of hind tibia 71–98, 80 µm and 64–94, 78 (6) µm long. Width at apex of fore tibia 98–128, 105 µm; of mid tibia 79–113, 97 µm; of hind tibia 90–113, 105 µm. Pseudospurs present on ta1 and ta2 of all legs and occasionally on ta3 of hind leg, 45–83 µm long. Tarsal claws bifid and asymmetrical, pectinate arm and simple arm subequal in length on one claw, about half as long on other claw. Lengths of claws not accurately measurable, but distance from base to apex about 100 µm long on all legs, with distance from base to apex of shorter pectinate arm about 80 µm. Lengths and proportions of legs as in Table 1.

Hypopygium ( Figs 4–6 ). Tergite IX weak, unsclerotized, with 2–7, 4 very weak setae; laterosternites each with 8–22, 13 setae. Aedeagus complex with several apodemes, mesal sclerites nearly straight and without hooked tips, 191–248, 209 µm long. Gonocoxite 349–413, 383 µm long; mesally strongly widened, width 180–221, 203 µm; width basally of enlargement 128–146, 141 µm. Gonostylus 154–188, 173 µm long; 75–94, 85 µm wide. HR 2.04– 2.23, 2.13; HV 2.63–3.32, 3.05.

Female (n = 8, except when otherwise stated). Total length 4.48–5.79, 4.95 mm. Wing length 3.31–4.19, 3.61 mm. Total length / wing length 1.33–1.47, 1.37. Wing length / length of profemur 2.66–2.87, 2.77.

Coloration. General dark brown with vittae and markings blackish. Legs and abdomen brown with apophyses and genitalia darker. Wings slightly brown.

Head. Pedicel 98–116, 110 µm long; 98–116, 107 µm wide; with 29–55, 38 setae. Six flagellomeres. AR 0.41– 0.61, 0.51. Lengths (in µm) of flagellomeres: 98–116, 105; 34–45, 41; 34–53, 43; 34–45, 39; 30–41, 34; 98–146, 129. First flagellomere with 1–3, 2 setae; second and third each with 1–2, 1; fourth and fifth each with 0–1, 1; sixth flagellomere with 3–5, 3 setae. Several flagellomeres often partly fused. Temporal setae 31–44, 37 including 6–10, 7 very strong postorbitals; 6–8, 7 outer verticals; 12–20, 16 inner verticals; and 6–9, 7 very strong orbitals. Clypeus with 45–83, 66 setae. Palpomere lengths (in µm): 34–53, 42; 45–68, 55; 90–124, 109. First palpomere very weak and indistinct.

fe ti ta1 ta2

p1 1666–2064, 1853 1689–2111, 1840 1009–1290, 1096 352–446, 392

p2 2229–2745, 2473 1877–2323, 2102 633–845, 744 258–228, 295

p3 2158–2839, 2474 1900–2299, 2101 1056–1290, 1160 504–680, 551

ta3 ta4 ta5 LR

p1 141–188, 158 117–164, 142 117–164, 142 0.57–0.62, 0.60

p2 164–223, 191 129–176, 149 117–141, 136 0.33–0.38, 0.35

p3 211–258, 231 141–188, 161 117–164, 139 0.53–0.57, 0.55

BV SV BR

p1 4.94–5.70, 5.22 3.27–3.53, 3.38 0.9–1.4, 1.1

p2 6.71–7.45, 6.90 5.71–6.70, 6.17 0.8–1.1, 0.9

p3 4.98–5.83, 5.36 3.90–4.23, 4.04 1.0–1.2, 1.1 Thorax. Antepronotum with 5–10, 7 weak setae. Dorsocentrals 5–10, 8, weak; prealars 6–16, 11; supraalar setae absent. Scutellum with 20–35, 26 setae of variable strength.

Wing ( Fig. 7 ). VR 0.94–1.07, 1.00. Costal extension indistinct, 30–68, 50 µm long. Brachiolum with 5–10, 7 setae; R with 13–33, 18; R1 with 4–9, 6; R4+5 with 11–23, 16 setae; other veins bare. Squama with 6–16, 9 weak setae.

Legs. Mid trochanter with 124–225, 165 µm long; 41–94, 60 µm wide projection. Hind trochanter with 94– 244, 153 µm long; 26–53, 36 µm wide projection. Spur of fore tibia 45–64, 55 µm long; spur of mid tibia absent in one specimen, 41–75, 52 µm long in the other; hind tibia with 2 spurs in 3 specimens, other 5 with single spur, 49– 90, 69 µm and 56–83 (3) µm long. Width at apex of fore tibia 75–101, 85 µm; of mid tibia 71–101, 86 µm; of hind tibia 71–113, 87 µm. Pseudospurs as in male. Tarsal claws all simple, slightly more than 100 µm long on all legs. Lengths and proportions of legs as in Table 2.

fe ti ta1 ta2

p1 1150–1571, 1308 1079–1571, 1258 610–917, 757 235–352, 276

p2 1642–2158, 1859 1173–1575, 1352 493–704, 593 188–238, 220

p3 1829–2323, 2060 1337–1760, 1547 687–1032, 846 352–516, 422

ta3 ta4 ta5 LR

p1 141–188, 166 117–141, 122 94–117, 103 0.57–0.65, 0.61

p2 117–188, 136 94–129, 104 82–117, 98 0.42–0.46, 0.44

p3 141–211, 160 94–129, 114 82–117, 100 0.53–0.59, 0.57

BV SV BR

p1 4.69–5.32, 5.00 3.06–3.65, 3.57 0.9–1.5, 1.1

p2 6.27–7.31, 6.87 5.20–5.71, 5.43 0.9–1.5, 1.2

p3 5.17–6.00, 5.62 4.02–4.50, 4.16 0.9–1.5, 1.3 Genitalia ( Figs 8–10 ). Tergite VIII with 15–24, 19 median setae of which many are not much more than strong microtrichia and each side with 5–7, 6 posterolateral setae. Sternite VIII darker anteriorly with 80–128, 102 setae of variable strength. Gonapophysis broad, without setae at base, with apical notch and 2 apical projections; main part 98–139, 123 µm long; projections each 34–45, 40 µm long. Gonocoxite without setae, but with numerous stronger microtrichia in addition to normal microtrichia. Gonostylus well developed, 304–398, 343 µm long; with median apodeme and strong parallel postero-laterally directed microtrichia giving gonostylus a striped appearance. Cercus 304–375, 334 µm long. Notum 251–338, 284 µm long.

Pupa and larva. Unknown.

Remarks. Wirth (1947, 1949) revised the genus. Since that time the genera Paraclunio Kieffer, 1911 and Psamathiomyia Deby, 1889 have been synonymized with the genus and Oliveira (1950, 1954, 2000) has described three new species. Telmatogeton goughi is close to T. sanctipauli Shiner, 1868 and T. minor (Kieffer, 1914) ( Hesse 1934: 34) resembling both in having bifid asymmetrical claws with pectinate arms well developed, most flagellomeres with one or more setae, mid-trochanters with pubescent or hairy knob-like projection, circum-ocular (postorbital and orbital) setae very strong and gonocoxite strongly widened apicomedially. It differs from T. sanctipauli in having a smaller size (wing length 3–4 mm as opposed to 5–6 mm); fewer scutellars (22–33 as opposed to about 50); having pectinate arm and simple arm subequal in length on one claw, about half as long on the other claw; mid-trochanter with knob-like projection about twice as long as broad (as long as broad in T. sanctipauli ) and mesal sclerites nearly straight (not sinuous as in T. sanctipauli ) and without hooked tips (hooked in T. sanctipauli ). From T. minor it differs in having a darker coloration and higher chaetotaxy with 22–33 scutellars as opposed to about 12. Telmatogeton eshu Oliveira, 2000 apparently also is similar in many details, but differs significantly in the male aedeagus, by having about 30 setae on squama and female genitalia apparently with a much shorter gonostylus.

Distribution. The species is known from Gough Island, Tristan da Cunha and Inaccessible Island.

Figures

FIGURES 2 – 6. Telmatogeton goughi sp. n., male. 2 — cibarial pump; 3 — wing; 4 — hypopygium, dorsal view; 5 — hypopygium, ventral view; 6 — aedeagus and internal apodemes.

FIGURES 7 – 10. Telmatogeton goughi sp. n., female. 7 — wing; 8 — genitalia, dorsal view; 9 — genitalia, ventral view; 10 — notum, spermathecal ducts, labia, gonapophyses and gonostyli.