Polypedilum (Tripodura) goiocoio, 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 : 525-527

Polypedilum (Tripodura) goiocoio sp. n.

( Figs. 4 A–E)

Type material. Holotype: male, Brazil, São Paulo State, Campos do Jordão, Casquilho Stream , 4 th order, 22°39’49”S, 45°27’04”W, 1535 m a.s.l., 13.ix.2001, M. T. Suriano. ( MZUSP) . Paratype: male, same date as holotype. ( LEIA) .

Etymology. From the indigenous Tupi-Guarani language, Goio-Coió, which means the one who comes from the river. 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 completely bare distally and apically pointed, also presenting 2 inner setae and a lateral seta; inferior volsella distally swollen, with an apical and 13–15 dorsal setae; anal point short and wide, with lateral lobes; wings with dark marking; scale of fore tibia dark brown with a well-developed and apically pointed spur.

Descriptions. Male (n=2). Total length 3.52–3.66 mm. Wing length 2.2–2.37 mm. Total length/wing length 1.49–1.66. Wing length/length of profemur 2.7–2.85.

Coloration: Head dark brown; thorax with darker scutellum and preepisternum; wings with dark markings ( Fig. 4A ); legs yellow, all femora with light brown band from the base to the middle, all tibiae dark brown in the junction with ta1, the same for ta1–ta2 and ta2–ta3 junctions; scale of fore tibia dark brown ( Fig. 6D ); each abdominal segment with a dark brown band proximally, which become wider toward the hypopygium.

Head. Antenna with 13 flagellomeres. AR 0.64–0.94. Ultimate flagellomere 415–531 µm. Frontal tubercle absent. Temporal setae 14 (1). Dorsomedial extension 115–123 µm. Clypeus 118–119 µm long, 97–100 µm wide, bearing 21–26 setae. Lengths of palpomeres 1–5 (in µm): 31–38, 47–62, 112–125, 125–134, 112–166, respectively. Eyes bare.

Thorax. 24 (1) acrostichals, 22–24 dorsocentrals uniserial, 4 prealars, scutellum with 12–20 setae in a single row.

Wing ( Fig. 4A ). Width 0.60–0.62 mm. VR 1.21–1.22. R with 20–24 setae, R 1 with 17–18, R 4+5 with 28–36 setae. Brachiolum with a seta. Squama with 9–10 setae. Anal lobe well developed.

Legs. Scale of fore tibia 55–61 μm long, triangular with a large spur 17–20 μm ( Figs. 4B , 6D ). Spur of middle tibia 59–61 μm long including 24–26 μm long comb. Spur of hind tibia 70–71 μm long including 31–32 μm long comb. Lengths and proportions of legs as in Table 4.

Hypopygium ( Figs. 4C, D ). Tergite IX with 8–10 median setae. Anal point 40–46 μm short, broad and crested, with lateral lobes and 10 lateral setae in each side of the anal point. Gonocoxite 74–85 μm long. Phallapodeme 29–35 μm long; transverse sternapodeme 54–69 μm long. Superior volsella 54–56 μm long pointed and apically bare, with 2 inner setae and a lateral seta ( Fig. 4E ). Inferior volsella 106–118 μm long with 13–15 dorsal setae and an apical seta. Gonostylus 157–164 μm long. HR 0.47–0.52. HV 2.23–2.24.

Taxonomic discussion. This new species is placed in the subgenus Tripodura due to the combination of wing membrane without macrotrichia, and with dark markings, the broad and pad-like superior volsella, and the presence lateral lobes to each side of the anal point. The pad-like shape of the superior volsella is frequently considered the most important diagnostic character to define Tripodura species. The superior volsella of P. (T.) goiocoio sp. n. is apically pointed. However it differs completely from the typical projection found in the superior volsella of Polypedilum s. str. or in the acifer group. Different from most of the Tripodura species, this new species does not present the superior volsella completely covered with microtrichia.

This new species notably differs from all its congeners. According to the key provided by Bidawid-Kafka (1996), the new species resembles P. (T.) cocama Bidawid-Kafka, 1996 due to some characters, such as the shape and setation of inferior volsella (distally swollen, with more than four dorsal setae) and the sharp end of the superior volsella. However, both species noticeably differ by the shape of the anal point. In the new species, the anal point is much smaller than in P. (T.) cocama . Additionally, the superior volsella of P. (T.) cocama is completely hairy, while in the new species the superior volsella is distally bare.

Figures

FIGURE 4. A–E. Polypedilum (Tripodura) goiocoio 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.