Tanytarsus chicomendesi, 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 : 120-122

Tanytarsus chicomendesi sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:B37F4D29-033E-4133-B27E-6BB607964385

( Fig. 3A–F )

Type material. Holotype ♁, BRAZIL, Acre, Mâncio Lima, PARNA Serra do Divisor, Morro da Poranga stream, 7°25′47″S, 73°39′43″W, 260 m a.s.l., 19–27.vii.2022, Malaise trap, G. R. Desidério, A.M.O. Pes, J.O. Silva, R. B. Pinedo, H.L.M.S. Ferreira ( INPA) . Paratypes: 2 ♁♁ ( INPA), same data as holotype .

Derivatio nominis. The specific epithet is a tribute to Francisco Alves Mendes Filho, better known as “Chico Mendes”, a Brazilian rubber tapper, trade union leader and environmentalist. He fought to preserve the Amazon rainforest and advocated for the human rights of Brazilian peasants and Indigenous peoples. Chico Mendes was born and lived in Acre, the same Brazilian state where the new species was found, and he was cowardly assassinated on 22 December 1988. Noun in apposition.

Diagnosis. Minute species, body length <1.7 mm, wing length <0.9 mm. Frontal tubercles absent. Tergite IX covered with microtrichia on the entire surface, median setae present, lateral teeth absent, tergite bands V-type, widely separated, curved. Anal point elongate, slender, with 3–4 spinulae and one minute spiniform seta between anterior part of crests. Superior volsella roundish or ellipse-shaped, with anteromedian tubercle extending beyond its margin; digitus finger-like, reaching or extending slightly beyond posteromedian margin of superior volsella. Stem of median volsella slightly swollen apically, with setiform and foliate lamellae. Inferior volsella with dorsoapical swelling.

Description. Adult male (n = 3)

Body size and proportions. Total length 1.45–1.62 mm. Wing length 0.82–0.85 mm. Total length/wing length 1.74–1.91. Wing length/length of profemur 2.22–2.24.

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

Head. Eyes bare, without dorsomedian extensions. Antenna with 13 flagellomeres; ultimate flagellomere 170– 178 μm long; AR 0.45–0.50. Frontal tubercles absent. Tentorium 70–75 μm long. Temporal setae 5–7 on each side. Clypeus with 8–11 setae. Lengths of palpomeres 1–5 (in μm): 15–18, 20–22, 62–65, 70–75, 120; third palpomere with 2 sensilla clavata subapically, 8–9 μm long.

Thorax. Ac about 20, restricted to anterior region of scutum; Dc 5 on each side, uniserial; Pa 1 on each side; Scts 2. Scutum projected and rounded anteriorly, overreaching antepronotum.

Wing. Obovate, with anal lobe strongly reduced. Almost all veins (except subcosta) and entire membrane posterior to radial veins area (except 1/2 basal of m, cubital and base of anal cell) covered with macrotrichia. Brachiolum with 1 seta. VRCu 1.32–1.36.

Legs. Foreleg tibia with short lanceolate spur 10–12 μm long. Tibial combs of mid and hind legs separated; spurs of mid leg unequal: one apically curved, 15–16 μm long, second straight, 8–10 μm long; spurs of hind leg unequal: one apically curved, 16–18 μm long, second straight, 10–12 μm long. Basitarsus of mid leg without sensilla chaetica. Lengths and proportions of legs as in Table 2.

Hypopygium. Tergite IX covered with dense short microtrichia on entire surface, with 4 median setae, and 5–6 setae on each side of anal point; lateral teeth absent; tergite bands V-type, widely separated, curved, running parallel at middle of tergite ( Fig. 3A, C ). Anal point elongate, slender, crests well-developed, microtrichia between crests usually present; 3–4 spinulae in regular row or placed irregularly, and one minute spiniform seta between anterior part of crests ( Fig. 3A, C ). Superior volsella 22–24 μm long, roundish or ellipse-shaped, posteriomedian part slightly projected, anteromedian tubercle distinctly extending beyond margin of superior volsella; 4 setae dorsally, 2 setae on median margin and 1 seta on anteroventral tubercle, microtrichia on dorsal surface absent; digitus finger-like, 14–16 μm long, reaching or extending slightly beyond posteromedian margin of superior volsella ( Fig. 3A–D ). Stem of median volsella slightly swollen apically, 10 μm long, with setiform and foliate lamellae ( Fig. 3E, F ). Inferior volsella 40–45 μm long, slightly sinuous, posteromedially directed, with distinct dorsoapical swelling ( Fig. 3A, B ). Phallapodeme 45–52 μm long; transverse sternapodeme 32–35 μm long, with well-developed oral projections. Gonocoxite 60–65 μm long. Gonostylus 45–50 μm long, slightly swollen at mid length, tapering to slender tip. HR 1.30–1.33, HV 3.24–3.27.

Female and immature stages. Unknown.

Taxonomy. The adult male of Tanytarsus chicomendesi is the smallest within those of studied here, and one of the smallest within Neotropical Tanytarsus . The body and the wing lengths (1.45–1.62 mm | 0.82–0.85 mm) are comparable with those of T. longitubuli Trivinho-Strixino, Wiedenbrug et da Silva, 2015 (1.65–1.73 | 0.90–1.05) and several species formerly ascribed to Caladomyia , with probably the smallest T. erikae ( Reiff, 2000) having the wing 0.74–0.78 mm long (cf. Säwedal 1981, Reiff 2000, Trivinho-Strixino 2012, Trivinho-Strixino et al. 2015). The lack of frontal tubercles, the anal point shape and its armature consisting of spinulae and the minute spiniform seta, the ellipse-shaped superior volsella, with the well-developed anteromedian tubercle, and the long finger-like digitus form a set of characters best separating T. chicomendesi from other Tanytarsus .

Geographical distribution and bionomics. Tanytarsus chicomendesi is known only from the type locality in the western Brazilian Amazon ( Fig. 1C, D ). The type locality is in the Serra do Divisor National Park (SDNP), which encompasses a mountain range located on the border between Brazil and Peru, in the Amazon region. This is a region of great ecological importance, as some of the main rivers of the Amazon basin, such as Juruá and Tarauacá, originate there. Although the SDNP is considered one of the most preserved and biodiverse areas in the world, hosting several endemic species ( Whitney et al. 2004, Silveira et al. 2008, Dolibaina et al. 2015, Bernarde et al. 2016), this region has been suffering serious threats due to disastrous environmental and economic policies ( Koga et al. 2022, Ruaro & Laurance 2022). This situation highlights the urgent need to study the biodiversity of the region, as this knowledge is crucial for developing effective conservation strategies.

Figures

FIGURE 1. Sites of sampling the type material in Peru (A, B) and Brazil (C, D).

FIGURE 3. Tanytarsus chicomendesi sp. nov., male. A, B: hypopygium in dorsal (A) and ventral aspect (B); C: anal point and superior volsellae in dorsal aspect; D: superior volsella and digitus; E, F: median volsellae photographed (E) and drawn (F); C–F magnified × 1,5–3 relative to A and B; superior volsella in the drawings (red) with anteroventral tubercle (yellow), and digitus (green).