Tanytarsus insolens Dantas & Giłka 2017, sp. nov.
Creators: name: Dantas, Galileu P. S.
name: Giłka, Wojciech
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Chironomidae
Tanytarsus
Tanytarsus insolens

description: Tanytarsus insolens sp. nov.
(Figs 3 A–F; 4C)
Type material. Holotype, adult male: BRAZIL, Amazonas state, Puraquequara near Manaus (02°43'02"S / 59°54'04"W), 0 7 July 2015, Malaise trap, G.P.S. Dantas (INPA). Paratypes: 4 males (1 INPA, 3 DIZP), same data as for holotype except for date: 19 June 2015.
Derivatio nominis. From Latin insolens (unusual, extraordinary).
Diagnosis. Tergite IX with sparse long hair-like macrotrichia. Anal point triangular, bearing several spinulae, with the most distal one enlarged, bar-like. Anterior (ventral) projection of superior volsella finger-shaped, posterior (dorsal) projection narrowly triangular, pointed. Digitus large, lanceolate or knife-shaped, broadly fused with posterior projection of superior volsella. Median volsella with 4–5 subulate lamellae.
Description. Adult male (n = 5).
Body size and proportions. Total length 2.31–2.49 mm. Wing length 1.25–1.31 mm. Total length/wing length 1.80–1.98. Wing length/length of profemur 1.58–1.68.
Colouration. Eyes black. Antenna, palp, scutal vittae and postnotum brown. Head capsule, ground colour of thorax, scutellum, sternum and haltere yellow to light brown. Fore leg: coxa and trochanter yellow, femur and tibia brown. Mid and hind legs: coxae, trochanters and proximal half of femora yellow, distal half of femora, tibiae and tarsi brown. Wing veins brown, membrane with brownish undertone. Abdomen yellow, gradually becoming brown posteriorly; segments with darker margins dorsally (transversal bands), distinctly standing out from lighter background.
Head. Eyes bare, with well developed dorsomedian extensions. Antenna with 13 flagellomeres; ultimate flagellomere 405–440 µm long; AR 0.85–0.88. Frontal tubercles absent or in shape of minute swellings (ca. 2 µm). Tentorium 118–125 µm long. Temporal setae 7–10 on each side. Clypeus with 11–14 setae. Lengths of palpomeres 1–5 (in µm): 30–40, 36–48, 115–127, 107–119, 195–226; third palpomere with 2 sensilla clavata subapically, 10– 12 µm long.
Thorax. Ac 11–20, restricted to anterior region of scutum; Dc 5–7 on each side, uniserial; Pa 1 on each side; Scts 5–6. Scutum projected and rounded anteriorly, overreaching antepronotum.
Wing. Obovate, with anal lobe strongly reduced, as shown in Fig. 4 C. Almost all veins and entire membrane below radial veins covered with macrotrichia. Brachiolum with 1 seta. VR Cu 1.27–1.35.
Legs. Fore leg tibia with short lanceolate spur 8–15 µm long. Tibial combs of mid and hind legs separated, only one comb bearing slightly bent apically spur, 32–42 µm (mid leg) to 37–52 µm long (hind leg). Basitarsus of mid leg with 1–2 sensilla chaetica. Lengths and proportions of legs as in Table 3.
Hypopygium (Fig. 3 A–F). Tergite IX covered with dense short microtrichia on entire surface, sparse hair-like 10–15 µm long macrotrichia in anterior part (Fig. 3 A, C) and 20–25 stout setae around base of anal point. Lateral teeth absent. Anal tergite bands Y-shaped, fading at base of anal point. Anal point triangular, with short round crests flanking 4–7 spinulae, with the most distal one enlarged, bar-like (Fig. 3 A, D). Superior volsella bilobed: anterior (ventral) projection finger-shaped, with 3–4 apical/subapical setae, posterior (dorsal) projection narrowly triangular, pointed, bearing 4 short setae dorsally (2 proximal + 2 distal); digitus large, extending far beyond superior volsella, somewhat lanceolate or knife-shaped, broadly fused with posterior projection of superior volsella as shown in Fig. 3 A, B, E. Stem of median volsella simple, 12–15 µm long, with 4–5 subulate lamellae (Fig. 3 B, F). Inferior volsella 70–85 µm long, evenly curved and posteromedially directed, with distinct longitudinal ridge dorsally. Phallapodeme 65–75 µm long; transverse sternapodeme 53–64 µm long, with well developed oral projections. Gonocoxite 102–109 µm long. Gonostylus 98–107 µm long, narrow, evenly curved and tapering toward blunt apex. HR 1.02–1.08, HV 2.17–2.52.
Discussion. The adult male of Tanytarsus insolens displays several distinct characters treated as diagnostic for a new group here proposed for this new species and T. kiche. The two species are unique in having the hypopygial superior volsella divided into two lobes or projections: anterior (ventral) and posterior (dorsal), and the stout digitus, extending far beyond the superior volsella. For homology of these structures in Tanytarsus insolens and T. kiche, see Fig. 3 E and G. The round anal point crests flanking the spinulae, with the most distal one separated from the others or enlarged and bar-shaped are also characters common for the two species, so treated as supporting the group concept (cf. Fig. 3 A, D and Vinogradova et al. 2009: fig. 2). Another extraordinary character found in males of Tanytarsus insolens are the long hair-like macrotrichia on the anal tergite (Fig. 3 A, C). This peculiar character, however, does not appear in males of Tanytarsus kiche (Spies, pers. comm.), thus should be treated as an autapomorphy as long as it is known from T. insolens exclusively. The two representatives of the kiche group are distributed across Central America, from Mexico in the north through Panama (T. kiche) to the Brazilian Amazonia in the south (T. insolens).
description: Published as part of Dantas, Galileu P. S. & Giłka, Wojciech, 2017, New Tanytarsus van der Wulp from the Brazilian Amazonia indicate clues to intrageneric relations (Diptera: Chironomidae), pp. 281-291 in Zootaxa 4294 (2) on pages 287-290, DOI: 10.11646/zootaxa.4294.2.10, http://zenodo.org/record/831730