Polypedilum (Tripodura) ybytyra, Shimabukuro & Trivinho-Strixino & Lamas, 2019

Shimabukuro, Erika Mayumi, Trivinho-Strixino, Susana & Lamas, Carlos José Einicker, 2019, New Polypedilum Kieffer (Diptera: Chironomidae) from mountains of the Atlantic Forest, Brazil, Zootaxa 4612 (4), pp. 518-532 : 527-528

Polypedilum (Tripodura) ybytyra sp. n.

( Figs. 5 A–E)

Type material. Holotype: male, Brazil, São Paulo State, Campos do Jordão, Campo do Meio Stream , 2 nd order, 22°41’35”S, 45°29’23”W, 1500 m a.s.l., 10.ix.2001, M. T. Suriano. ( MZUSP) . Paratype: male, same as holotype, except for the date 11.ii.2002, M. T . Suriano. ( LEIA).

Etymology. From the indigenous Tupi-Guarani language, Ybytyra, which means mountain, in reference to the type locality. The name is to be treated as a noun in apposition.

Diagnostic characters. The male of this new species can be separated from other members of the subgenus Tripodura by the combination of the following characters: superior volsella broad from the base to the apex and distally rounded, completely hairy and with a lateral seta emerging from a stalk; inferior volsella with 10–12 dorsal setae randomly distributed, an apical seta and a ventral seta; anal point broad but tapered in the base, without lateral lobes; broad gonostylus, tapering distally; wings with markings.

Descriptions. Male (n=2). Total length 5.52 (1) mm. Wing length 2.32–2.54 mm. Total length/wing length 2.01. Wing length/length of profemur 2.58 (1).

Coloration: Head dark brown; thorax with darker scutum and postnotum, pale spots at the insertion of setae; wings with weak markings ( Fig. 5A ) legs yellow, profemur light brown, mid femur and hind femur brown at the junction with tibiae; each abdominal segment with dark bands, pale spots at the insertion of setae.

Head. Antenna with 13 flagellomeres. AR 1.32. Ultimate flagellomere 812 µm. Frontal tubercle absent. Temporal setae 12–14. Dorsomedial extension 169–178 µm. Clypeus 129–159 µm long, 108–128 µm wide, bearing 24–28 setae. Lengths of palpomeres 1–5 (in µm): 21–27, 44–50, 138–175, 172–188, 244–306, respectively. Eyes bare.

Thorax. 23 (1) acrostichals, 19 (1) dorsocentrals uniserial, 7 prealars, scutellum with 21–26 setae bisserial. Presence of a small scutal tubercle with 12.5–31 μm ( Fig. 6F ).

Wing ( Fig. 5A ). Width 0.72–0.74 mm. VR 1.11–1.19. R with 25–29 setae, R 1 with 24–48, R 4+5 with more than 48 setae. Brachiolum with a seta. Squama with 9–14 setae. Anal lobe well developed.

Legs. Scale of fore tibia 60–72 μm long, triangular with a small spur 5–6 μm ( Figs. 5B , 6E ). Spur of middle tibia 64–68 μm long including 30–33 μm long comb. Spur of hind tibia 60–68 μm long including 27–29 μm long comb. Lengths and proportions of legs as in Table 5.

Hypopygium ( Figs. 5C, D ). Tergite IX with 9–12 median setae. Anal point 77–80 μm long, broad and crested, with 8 setae in each side of the anal point and without lateral lobes. Gonocoxite 74–125 μm long. Phallapodeme 83–103 μm long; transverse sternapodeme 68–78 μm long. Superior volsella 55–66 μm long with a lateral seta emerging from a stalk ( Fig. 5E ). Inferior volsella 115–126 μm long with 10-13 dorsal setae, an apical and a ventral ones. Gonostylus 182–216 μm long. HR 0.41–0.58. HV 2.56.

Taxonomic discussion. This new species is placed in the subgenus Tripodura due to the combination of wing membrane without macrotrichia and the broad and pad-like superior volsella. Although the new species does not present lateral lobes in the anal point and present a small scutal tubercle (uncommon for the subgenus), we considered the presence of a broad superior volsella more important to define Tripodura species. According to Vårdal et al. (2002) only about 50 percent of the species with pad-like superior volsella present lateral lobes (or shoulders).

This new species is similar to P. (T.) xavante Bidawid et Fittkau, 1995 due to the presence of dark marking on wings, the shape of the superior volsella, which is broad from the base to the apex and apically rounded, and the broad anal point, tapered in the base and without lateral lobes. However, the new species differs from P. (T.) xavante by the absence of frontal tubercle, the absence of inner setae on superior volsella ( P. (T.) xavante has three inner setae on superior volsella) and dark marks on legs ( P. (T.) xavante has uniformly dark legs).

Figures

FIGURE 5. A–E. Polypedilum (Tripodura) ybytyra sp. n. male adult. A, wing. B, scale of fore tibia. C. hypopigyum, dorsal view. D, hypopigyum with tergite IX removed, dorsal view. E, superior volsella.

FIGURE 6. A–E. Scale of fore tibia. A, Polypedilum (Polypedilum) caete. B, Polypedilum (Polypedilum) aymbere. C, Polypedilum (Tripodura) yvatekaty. D, Polypedilum (Tripodura) goiocoio. E, Polypedilum (Tripodura) ybytyra. F. Thorax of P. (T.) ybytyra with the detail of the scutal tubercle.