Tanytarsus cayambe, Giłka, Wojciech & Zakrzewska, Marta, 2013

Giłka, Wojciech & Zakrzewska, Marta, 2013, A contribution to the systematics of Neotropical Tanytarsus van der Wulp: first descriptions from Ecuador (Diptera: Chironomidae: Tanytarsini), Zootaxa 3619 (4), pp. 453-459 : 454

Tanytarsus cayambe sp. nov.

Type material. Holotype, adult male: ECUADOR, Pichincha province, San Miguel de Los Bancos (canton), Mindo, c. 1400 m a.s.l., 25–31 August 1999, netting, leg. Dawid Graczyk. Paratype, adult male: same data as holotype.

Derivation of the name. The specific name is referred to the Cayambe , the second biggest volcano in the Pichincha province where the specimens were collected. The name should be treated as a noun in apposition.

Diagnosis. AR low, 0.35–0.40. Sc with numerous macrotrichia. Anal tergite with several median setae. Anal tergite bands of V-type, short, broadly separated. Anal point long, with distinct club-shaped prolongation and single strong spine placed between crests. Superior volsella circular, with slightly concave apex. Digitus subtriangular, extending beyond superior volsella, apically pointed. Median volsella with several slender pectinate and two long setiform lamellae.

Description. Adult male (n = 1 or 2)

Wing length 1.53–1.64 mm.

Colouration. Eyes black; antennal pedicel, head capsule, ground colour of thorax, scutellum, haltere, proximal parts of legs and abdomen greenish yellow; wing membrane with greenish undertone; remaining body parts slightly darker, pale brown.

Head. Antenna with 13 flagellomeres; AR 0.35–0.40. Frontal tubercles conical, 8 μm long. Length of palpomeres II–V (μm): 36–44, 96–109, 101–117, 193 (n = 1). Clypeus with 11–16 setae.

Thorax chaetotaxy. Ac 11–13, Dc 8–9 on each side, Pa 1 on each side, Scts 4–5.

Wing. Fig. 1 A. Entire membrane below radial veins covered with dense macrotrichia; Sc with numerous macrotrichia.

Legs. Fore tibia with straight slender spur. Tibial combs of mid and hind leg separated; spurs of mid and hind leg similar in shape, both slightly curved, one spur twice as long as the second. Basitarsus of mid leg bearing 4 hook-shaped sensilla chaetica (n = 1). Length of leg segments and leg ratios in Table 1 .

Hypopygium ( Fig. 1 B–D). Gonostylus 105–115 μm long, slightly swollen in proximal part, tapering to slender tip. Anal tergite with 5–10 median setae. Anal tergite bands of V-type, short, broadly separated. Anal point long, slightly constricted in mid length with distinct club-shaped prolongation, tip broadly rounded with 3 lateral setae on each side and single strong spine placed between short crests; entire area surrounding base of anal point covered with microtrichia ( Fig. 1 B, C). Superior volsella circular, with slightly concave apex, 6 dorsal and 3 anteromedian setae, microtrichia absent. Digitus subtriangular, distorted at mid length, extending slightly beyond superior volsella, apically pointed. Inferior volsella with distinctly broadened head-like apex, and wide darkly coloured dorsomedian ridge ( Fig. 1 B). Stem of median volsella 12 μm long, club-shaped, slightly curved, bearing 4 slender pectinate and 2 long setiform lamellae ( Fig. 1 D).

Discussion. A group membership of Tanytarsus cayambe is not certain. The new species shows several characters typical for the recurvatus group (Holarctic and Oriental regions), i.e. the short anal tergite bands of Vtype, the anal point elongate with the distinct lanceolate or club-shaped prolongation and the superior volsella roundish with concave apex. However, the new species has the strong hypopygial median setae and the anal point is armed with the single spine, whereas the median setae and spines/spinulae are absent in the recurvatus group. The single spine or short seta instead typical spinulae are known from several Neotropical Tanytarsus : T. monospinosus Ekrem et Reiss, T. jacaretingensis Sanseverino et Fittkau and T. rinihuensis Reiss (Reiss 1972, Ekrem & Reiss 1999, Sanseverino & Fittkau 2006). The latter species and T. cayambe are also distinct in having subcostal wing vein covered with macrotrichia. This character is discussed by Sanseverino (2006) and mentioned as not common among Neotropical Tanytarsus . Interestingly, two other Brazilian species, i.e. Tanytarsus impar Trivinho-Strixino et Strixino and Tanytarsus magnus Trivinho-Strixino et Strixino , which show setae on Sc, have the anal point spinulae also not developed (Trivinho-Strixino & Strixino 2004). All the above species seem to be closely related, however, their group membership needs further studies in the course of exploring the Neotropical Tanytarsus .

Figures

FIGURE 1. Tanytarsus cayambe sp. nov., adult male. A—wing, B—hypopygium, C—anal point (variability), D—median volsella (magnified x 2 relative to hypopygium).

Tables

TABLE 1. Lengths (μm) of leg segments and leg ratios of male Tanytarsus cayambe sp. nov.

fe	ti	ta1	ta2	ta3	ta4	ta5	LR
P1 720	365–385	1030–1095	460–495	395	300–310	135–145	2.82–2.83
P2 760–805	565–620	385	200	140	95	70	0.68
P3 790–855	685–760	520	300	270	170	95	0.76