Tanytarsus frameatus, Dantas & Hamada & Giłka, 2023

Dantas, Galileu P. S., Hamada, Neusa & Giłka, Wojciech, 2023, Tanytarsus van der Wulp (Chironomidae, Diptera): new species from the western Amazon region in Peru and Brazil, new records from the Neotropics, and remarks on the taxonomy of the genus, Zootaxa 5271 (1), pp. 115-139 : 129-132

Tanytarsus frameatus sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:2A344199-7C3E-4C71-B406-77B785B022FE

( Fig. 7A–H )

Type material. Holotype ♁, PERU, Cusco, Quincemil, Araza river tributary, 13º20′10′′S, 70º50′57′′W, 874 m a.s.l., 23–31.viii.2012, Malaise trap, leg. J.A. Rafael, R. R. Cavichioli, D.M. Takiya ( MUSM) . Paratype: 1 ♁ ( INPA), same data as holotype .

Derivatio nominis. From Latin framea (spear, or hasta), in reference to the shape of the hypopygial anal point ( Fig. 7C ), the key character of the proposed Tanytarsus hastatus species group.

Diagnosis. Frontal tubercles relatively small, up to 10 μm long. Tergite IX covered with microtrichia on the entire surface, 2–6 median setae placed irregularly at base of anal point, lateral teeth vestigial, tergite bands Vshaped, widely separated. Anal point with 12–14 spinulae between well-developed crests. Superior volsella heart-shaped, with evenly concave median margin; digitus long, finger-like. Stem of median volsella simple, bearing several setiform and pectinate lamellae with wavy apices.

Description. Adult male (n = 2)

Body size and proportions. Total length 2.53–2.90 mm. Wing length 1.47–1.57 mm. Total length/wing length 1.72–1.85. Wing length/length of profemur 1.92–1.93.

Colouration. Head capsule and palps yellow to light brown, eyes black, antenna brown. Scutal vittae and postnotum light brown, ground colour of thorax, scutellum, and haltere yellow to pale brown. Legs and abdomen yellow to light brown. Wing veins yellowish to light brown, membrane with yellow undertone.

Head. Eyes bare, with well-developed dorsomedian extensions. Antenna with 13 flagellomeres; ultimate flagellomere 155–178 μm long; AR 0.28–0.31. Frontal tubercles 8-10 μm long. Tentorium 125–130 μm long. Temporal setae 7–9 on each side. Clypeus with 14–16 setae. Lengths of palpomeres 1–3 (in μm): 32, 38, 112; third palpomere with 4 sensilla clavata subapically, 18 μm long.

Thorax. Ac about 20–22, restricted to anterior region of scutum; Dc 8–10 on each side, uniserial; Pa 2 on each side; Scts 4–6. Scutum projected anteriorly, overreaching antepronotum.

Wing. Obovate, with anal lobe strongly reduced. Almost all veins (except subcosta) and entire membrane posterior to radial veins area (except 1/5 basal of m and ½ of cubital cell) covered with macrotrichia. Brachiolum with 1 seta. VRCu 1.27–1.31.

Legs. Foreleg tibia with lanceolate spur 20–25 μm long. Tibial combs of mid and hind legs separated; spurs of mid leg unequal: one apically curved, 32–33 μm long, second straight, 18–19 μm long; spurs of hind leg unequal: one apically curved, 36–38 μm long, second straight, 28–32 μm long. Basitarsus of mid leg with two sensilla chaetica. Lengths and proportions of legs as in Table 6.

Hypopygium. Tergite IX covered with dense short microtrichia on entire surface, 2–6 median setae placed irregularly at base of anal point, 5–7 setae on each side of anal point (+6 setae ventrally); lateral teeth vestigial; tergite bands V-shaped, widely separated, curved, fading at middle of tergite ( Fig. 7A ). Anal point lanceolate, with a pair of well-developed crests, microtrichia between crests absent, 12–14 spinulae placed irregularly ( Fig. 7A, C ). Superior volsella 32–33 μm long, heart-shaped, with evenly concave median margin, posteriomedian corner slightly projected, with ventral lip; 4 setae dorsally, 2 setae on median margin and 1 seta on anteroventral tubercle, microtrichia on dorsal surface absent; digitus 23–24 μm long, extending far beyond posteromedian margin of superior volsella ( Fig. 7A, B, D, E ). Stem of median volsella simple, 18–19 μm long, with setiform and pectinate lamellae (apices wavy) ( Fig. 7B, F–H ). Inferior volsella 70–80 μm long, with slightly swollen and posteromedially directed distal part ( Fig. 7A, B ). Phallapodeme 90–96 μm long; transverse sternapodeme 52–53 μm long, with small oral projections. Gonocoxite 98–110 μm long. Gonostylus 92–105 μm long, slightly swollen at mid length, tapering to round tip. HR 1.05–1.07, HV 2.75–2.78.

Female and immature stages. Unknown.

Taxonomy. Recent studies and a redescription of Tanytarsus hastatus have supported its exclusion from the riopreto group ( Dantas et al. 2022), as formerly proposed. However, indications of known species sufficiently close to be considered as relatives at the group level have so far remained problematic. Tanytarsus frameatus , described above, fits into this gap in knowledge and together with T. hastatus forms a species couple that is proposed as a separate group here. Both species share several features defined as key for the group (see the group diagnosis), and some characters clearly show they are distinct species. These are: relatively small frontal tubercles in T. frameatus (vs. large in T. hastatus ), vestigial lateral teeth of the anal tergite (vs. large), just over a dozen of spinulae (vs. 2 or 3 dozens of spinulae), heart-shaped superior volsella with an evenly concave median margin (vs. round, deeply concave), stem of median volsella simple (vs. swollen apically) (cf. Fig. 7 and Sublette & Sasa 1994, Sanseverino 2006, Dantas et al. 2022).

Geographical distribution and bionomics. Tanytarsus frameatus is known only from the type locality in the highlands of the Amazonian Forest in Peru ( Fig. 1A, B ). The adult male specimens examined were obtained along with those of four other species described in the present paper. For further information on the ecology and bionomics refer to the notes on Tanytarsus aries (above).

Figures

FIGURE 1. Sites of sampling the type material in Peru (A, B) and Brazil (C, D).

FIGURE 7. Tanytarsus frameatus sp. nov., male. A, B: hypopygium in dorsal (A) and ventral aspect (B); C: anal point; D, E: superior volsella and digitus photographed (D) and drawn (E); F–H: median volsellae photographed (F, G) and drawn (H); C–H magnified × 1,5–2 relative to A and B; superior volsella in the drawings (red) with anteroventral tubercle (yellow), and digitus (green).