Tanytarsus meta, Dantas & Amat & Hamada & Giłka, 2022

Dantas, Galileu P. S., Amat, Eduardo, Hamada, Neusa & Giłka, Wojciech, 2022, Towards the systematics and diversity of Neotropical Tanytarsus van der Wulp (Diptera: Chironomidae): news from Colombia, Zootaxa 5129 (4), pp. 505-529 : 518-520

Tanytarsus meta sp. nov.

LSID: urn:lsid:zoobank.org:act:770BE4EB-7B0F-4D80-9E7D-6BD6D04AF2AA

( Fig. 6A–F )

Type material. Holotype, adult male: COLOMBIA, Meta Department, Puerto Lopez , 04º08’11’’N 72º52’53’’W, 206 m a.s.l., 01–03 January 2021, Malaise trap, G.P.S. Dantas, S.M. R. Hernández, E.C.G. Amat (CETdeA).

Derivatio nominis. The specific epithet derived from the Meta Department in central Colombia, where the specimen was collected. Noun in apposition.

Diagnosis. Frontal tubercles well-developed, nearly 4 times as long as wide. Tergite IX covered with dense microtrichia on entire surface, with 7 median setae. Anal tergite bands V-shaped separated. Anal point broad at base, distinctly narrowed at mid length, with parallel-sided apical elongation, bearing slender crests and long trifid spinulae directed anteriorly. Superior volsella heart-shaped with median margin strongly concave and posteromedian corner well-developed. Digitus finger-like, pointed, not extending beyond median margin of superior volsella. Stem of median volsella bulbous, bearing several setiform and 3 foliate lamellae.

Description. Adult male (n = 1).

Body size and proportions. Total length 2.63 mm. Wing length 1.16 mm. Total length/wing length ratio 2.27. Wing length/length of profemur ratio 1.63.

Colouration. Eyes black. Antenna, scutal vittae and postnotum light brown. Head capsule, ground colour of thorax, scutellum, sternum and haltere yellow to light brown. Legs yellowish to light brown. Wing veins yellow, membrane pale. Abdomen yellow.

Head. Eyes bare, with well-developed dorsomedian extensions. Antenna with 13 flagellomeres; ultimate flagellomere 416 μm long; AR 0.90. Frontal tubercles well-developed, 18 μm long, 5 μm wide, 3.6 times as long as wide. Tentorium 115 μm long. Temporal setae 10 on each side. Clypeus with 17 setae. Lengths of palpomeres 1–5 (in μm): 30, 33, 90, 95, 150; third palpomere with 2 subapical sensilla clavata 16 μm long.

Thorax. Ac 14, restricted to anterior region of scutum; Dc 7 on each side, uniserial; Pa 3 on each side; Scts 4. Scutum projected and rounded anteriorly, overreaching antepronotum.

Wing. Typical of the genus. Almost all veins (except subcosta) and entire membrane posterior to radial veins area (except base of m and an cells) covered with macrotrichia. Brachiolum with 1 seta. VRCu 1.21. WW 0.29.

Legs. Foreleg tibia with straight lanceolate spur 16 μm long. Tibial combs of mid and hind legs separated; spurs of mid leg unequal: one bent, 32 μm long, second straight, 20 μm long; spurs of hind leg similar, both long and slightly sinuous: one 55 μm long, second 48 μm long. Basitarsus of mid leg without sensilla chaetica. Lengths and proportions of legs as in Table 5 .

Hypopygium. Tergite IX covered with dense short microtrichia on entire surface, 7 median setae (placed between anal tergite bands and anal point crests) and 7 lateral setae on each side of anal point; lateral teeth present, minute; anal tergite bands V-type, widely separated, ending well anterior to anal point base ( Fig. 6A, C ). Anal point 45 μm long, broad at base, with distinctly narrowed parallel-sided apical elongation, rounded apically, bearing slender crests flanking 7 long trifid spinulae placed irregularly and anteriorly directed ( Fig. 6A, C ). Superior volsella heart-shaped with median margin strongly concave and posteromedian corner well-developed, 10 setae on dorsal surface, 1 seta on median margin and 1 ventral seta close to median margin, field of microtrichia on dorsal surface absent; digitus 12 μm long, finger-like, pointed, not extending beyond median margin of superior volsella ( Fig. 6A, B, D ). Stem of median volsella bulbous, 22 μm long, with several setiform and 3 foliate lamellae ( Fig. 6B, E, F ). Inferior volsella 67 μm long, covered with microtrichia, straight and posteriorly directed, with apex slightly swollen. Phallapodeme S-shaped, ~85 μm long; transverse sternapodeme ~50 μm long, without oral projections. Gonocoxite ~90 μm long. Gonostylus 100 μm long, narrow, nearly straight, tapering towards blunt apex. HR 0.88. HV 2.63.

Distribution and ecological notes. The adult male specimen examined was collected together with those of Tanytarsus colombiensis , T.germani and T.lulu . For details on ecology and bionomics see notes under T colombiensis .

Discussion. The Tanytarsus riopreto species group was proposed by Fittkau and Reiss (1973) for four species: T. branquini , T. cuieirensis , T. cururui and T. riopreto . Later on, several further species ( T. clivosus , T. hamatus , T. hastatus , T. limneticus and T. pandus ) were proposed to be included ( Sublette & Sasa 1994), although when their diagnostic characters were comprehensively reanalyzed, their membership in the riopreto group was considered questionable (Sanseverino 2006). The group definition by Sublette and Sasa (1994) was refuted also on the basis of molecular analyses by Lin et al. (2018); consequently a more strict group definition and species composition were postulated. Following the concepts of Fittkau and Reiss (1973), Sanseverino (2006) and Lin et al. (2018), we accept the riopreto group with the original species composition, extended with T. meta described here. The adult male of T. meta fits well the group diagnosis, except for the structure of lamellae of the median volsella—with apices split into minute pectinations in the riopreto group vs. foliate lamellae, with simple apices in T. meta . However, if this subtle difference is not considered (the structure is often overlooked due to its size), the new species falls in the couplet 33 of the key to adult males of Neotropical Tanytarsus by Sanseverino (2006), leading to the riopreto group. The set of character best separating the male of T. meta and other species of the group are slight difference in the shape of the anal point, volsellae and a relatively short digitus in the new species [cf. the diagnosis given above and those of Fittkau & Reiss (1973) and Sanseverino (2006)].

Figures

FIGURE 6. Tanytarsus meta sp. nov., male. A, B: hypopygium in dorsal (A) and ventral aspect (B); C: anal tergite and anal point; D: superior volsella and digitus; E, F: median volsella photographed (E) and drawn (F); (C–F magnified ca. 2–3 times relative to A and B).