Tanytarsus serra, 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 : 127-129

Tanytarsus serra sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:764D4850-3F6A-4265-BF09-9B55CD4595A8

( Fig. 6A–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, J.A. Rafael, R. R. Cavichioli, D.M. Takiya ( MUSM) . Paratypes: 4 ♁♁ (2 MUSM, 2 INPA), same data as holotype .

Derivatio nominis. From Latin, in reference to the serrated or saw-like hypopygial anal point ( Fig. 6C–E ). Noun in apposition.

Diagnosis. Tergite IX covered with microtrichia on the entire surface, median setae and lateral teeth absent, tergite bands weak, fading at anteromedian part of tergite. Anal point slightly broadened subapically, apex round with slender process, without crests, bars or spinulae, lateral margins distinctly serrated. Superior volsella roundish, distal part slightly projected with a ventral lip; digitus finger-like, tapering to slender tip, not extending beyond margin of superior volsella. Median volsella with 3–4 setiform and 1–2 subulate lamellae.

Description. Adult male (n = 5)

Body size and proportions. Total length 1.95–2.51 mm. Wing length 1.06–1.55 mm. Total length/wing length 1.68–1.83. Wing length/length of profemur 1.91–2.06.

Colouration. Head capsule and palps yellow to faint brown, eyes black, antenna brown. Scutal vittae and postnotum brown, ventral portion of preepisternum light brown, ground colour of thorax, scutellum, and haltere yellow to faint brown. Legs yellowish to light brown. Wing veins yellowish to light brown, membrane with light brownish undertone. Abdomen yellow to light brown.

Head. Eyes bare, dorsomedian extensions developed.Antenna with 13 flagellomeres; ultimate flagellomere 170 μm long; AR 0.39. Frontal tubercles 6–7 μm long. Tentorium 98–105 μm long. Temporal setae 8–10 on each side. Clypeus with 10–13 setae. Lengths of palpomeres 1–5 (in μm): 25–28, 25–30, 88–95, 96–98, 165; third palpomere with 2 sensilla clavata subapically, 13–14 μm long.

Thorax. Ac 22–24, restricted to anterior region of scutum; Dc 7–8 on each side, uniserial; Pa 1 on each side; Scts 4. Scutum projected and rounded anteriorly, overreaching antepronotum.

Wing. Obovate, with anal lobe reduced. Almost all veins (except subcosta) and entire membrane posterior to radial veins area (except 2/3 basal of cubital cell) covered with macrotrichia. Brachiolum with 1 seta. VRCu 1.26–1.30.

Legs. Foreleg tibia with lanceolate spur 16–17 μm long. Tibial combs of mid and hind legs separated; spurs of mid leg unequal: one apically curved, 18–20 μm long, second straight, 12–14 μm long; spurs of hind leg unequal: one apically curved, 21–22 μm long, second straight, 17–19 μm long. Basitarsus of mid leg with two sensilla chaetica. Lengths and proportions of legs as in Table 5.

Hypopygium. Tergite IX covered with dense short microtrichia on the entire surface, median setae absent, 5–6 setae on each side of anal point; lateral teeth not observed; tergite bands weak, running transversally relative to main body axis, fading at anteromedian part of tergite ( Fig. 6A, C ). Anal point parallel-sided in basal part, slightly broadened subapically, tapering to round apex bearing slender process, without crests, bars or spinulae, dorsal surface concave, lateral margins distinctly serrated ( Fig. 6A, C–E ). Superior volsella 26–30 μm long, roundish, distal part slightly projected, with a ventral lip; 4–5 setae dorsally, 2 setae on median margin and 1 seta on anteroventral tubercle, microtrichia on dorsal surface absent; digitus finger-like, tapering to slender tip, 13–16 μm long, not extending beyond margin of superior volsella ( Fig. 6A, B, F, G ). Stem of median volsella simple, 15–16 μm long, with 3–4 setiform and 1–2 subulate lamellae ( Fig. 6B, F, H ). Inferior volsella 50–52 μm long, with slightly swollen and posteromedially directed distal part ( Fig. 6A, B ). Phallapodeme sinuous, 80 μm long; transverse sternapodeme 40 μm long, with distinct oral projections. Gonocoxite 75–88 μm long. Gonostylus 68–72 μm long, more or less parallel-sided, apically tapering to narrow apex. HR 1.10–1.24, HV 2.80–3.60.

Female and immature stages. Unknown.

Taxonomy. The distinctly serrated margins of the hypopygial anal point in the new species is another character within the extraordinary range of structural diversity of Tanytarsus . The general shape of the anal point of Tanytarsus serra (slightly broadened subapically and tapering to round apex bearing slender process) is similar to those of T. kraussi ( Säwedal, 1981) and T. poppigi ( Säwedal, 1981) originally described as Caladomyia . However, in T. serra it lacks any other structures typical of the compared species—crests, spinulae or bars [cf. Fig. 6 and Säwedal (1981) figs 15 & 18]. Such the peculiarly structured anal point in combination with other characters (see diagnosis) allows easy identification of the adult male.

Geographical distribution and bionomics. Tanytarsus serra 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 6. Tanytarsus serra sp. nov., male. A, B: hypopygium in dorsal (A) and ventral aspect (B); C–E: anal point photographed (C) and drawn in dorsal (D) and ventral aspect (E); F: median and superior volsellae in ventral aspect; G: superior volsella and digitus; H: median volsella; C–H magnified × 1.5–3 relative to A and B; superior volsella in the drawings (red) with anteroventral tubercle (yellow), and digitus (green).