Polypedilum (Asheum) curticaudatum Rempel, 1939

Pinho, Luiz Carlos & Silva, Fabio Laurindo Da, 2020, Description of two new species of Polypedilum (Asheum) and immature stages of Polypedilum (A.) curticaudatum (Diptera: Chironomidae), Zootaxa 4759 (2), pp. 179-190 : 184-188

Polypedilum (Asheum) curticaudatum Rempel, 1939

( Figures 3 and 4 )

Material analyzed. BRAZIL: 1 male, Bahia, Andaraí , 09.xi.2003, light, F Bravo ( UFSC) ; 1 male, Bahia, Feira de Santana, Campus UEFS, 20.v.2002, light, F Bravo ( UFSC) ; 1 male with pupal exuvia, São Paulo, Fazzari Reservoir , S21°58’17.9’’ W47°53’14.9’’, 23.iii.2014, S Trivinho-Strixino, ( MZSP) ; 1 male with larval and pupal exuviae, Santa Catarina, Florianópolis, Lagoa do Peri , S27°44’49.5’’ W48°32’02.3’’, 09.xii.2010, LC Pinho ( UFSC) ; 1 male, Santa Catarina, Joaçaba, Campus II Unoesc, 27.x–4.xii.2012, malaise, LC Pinho & GA Müller ( UFSC) ; 8 males, Mato Grosso do Sul, Corumbá, BEP—Mata Ciliar ( Rio Miranda ) S19°34’30.06” W57°00’52.4”, SISBIOTA— CNPq/FAPESP, Malaise 03, 03–18.x.2011, Lamas, Nihei & eq. col. ( MZSP) .

Diagnostic characters. Polypedilum (Asheum) curticaudatum can be separated from other Polypedilum species by combination of: Adult male: tergite VII not strongly tapered anteriorly, balloon shaped gonocoxite, short gonostylus and shape of superior volsella (see remarks). Pupa: Pedes spuri A and B absent, large dark spines on conjunctive IV/ V and wide L setae on abdominal segment IV. Larva: Teeth of mentum of even height, very broad ventromental plates, strongly curved latero-posteriorly (identical to P. (A.) beckae ).

Redescription. Adult male (n = 5, unless otherwise stated). Total length 3.41–3.90, 3.66 mm. Wing length 1.61–1.90, 1.78 mm. Total length / wing length 1.92–2.13, 2.04. Wing length / length of profemur 2.01–2.19, 2.11.

Coloration. Head light brown, palp brown. Thorax light brown with brown pigmentation at posterior area of scutum, postpronotum, postnotum, epimeron II and halter. Legs uniformly light brown. Abdominal tergite I brown, tergites II–VIII light brown with wide (about 0.6 of tergite length) transverse bands. Wings unmarked.

Head. Eyes bare, frontal tubercles absent. AR 2.18–2.30, 2.25; ultimate flagellomere 788–887, 827 μm long. Temporal setae 13–15, 14. Clypeus with 23–32, 28 setae. Tentorium 129–137, 134 μm long, 32–52,45 μm wide. Palpomere lengths (in μm): 35–47, 40, 40–55, 47, 122–142, 129, 122–129, 124, 173–237, 207. Third palpal segment with 4–6 sensilla clavata, longest 12–17, 15 μm.

Wing. VR 1.17–1.20, 1.19. Brachiolum with 1 seta. R with 23–27, 25 setae; R 1 with 16–20, 18, R 4+5 with 26–34, 31 setae, remaining veins bare. Squama with 10–18, 14 setae. Anal lobe weak.

Thorax. Scutum with low tubercle. Dorsocentrals 13–20, 19; acrostichals 18–26, 21; prealars 5–7, 6. Scutellum with 20–27, 23 setae, biserial.

Legs. Scale of foretibia 29–44, 34 μm long, rounded and without spur. Spur of midtibia 59–74, 69 μm long, including 39–69, 59 μm long comb. Spur of hind tibia 69–93, 78 μm long, including 74–83, 78 μm long comb. Width at apex of foretibia 49–59, 54 μm, of midtibia 54–59, 56 μm, of hind tibia 59–65, 62 μm. Lengths (in μm) and proportions of legs as in Table 4.

Hypopygium ( Figure 3 ). Tergite IX with 10–19, 12 median setae. Anal tergite band well developed. Laterosternite with 5–6, 5 setae. Anal point 37–42, 40 μm long, slender. Phallapodeme 105–134, 115 μm long, transverse sternapodeme 17–32, 25 μm long. Gonocoxite 194–214, 207 μm long. Superior volsella pediform with apical outer margin concave, 72–90, 80 μm long, basal 2/3 covered with microtrichia and with 4–5, 4 inner setae. Inferior vol- sella slender 87–110, 102 μm long, with 1 strong apical seta projecting caudad, and 17–26 orally directed setae. Gonostylus 92–115, 100 μm long. HR 1.70–2.30, 2.09; HV 3.39–3.70, 3.62.

Pupa. (exuviae, n = 2). Total length 3.91–3.98 mm.

Coloration. Exuviae pale with margins of wing sheath, leg sheath and thorax anteriorly brown.

Cephalothorax. Frontal apotome ( Fig. 4E ) slightly rounded, 137–157 μm long; 191–196 μm wide. Frontal setae 34–49 μm long. Distance between Dc1 and Dc2 5–7 μm; between Dc2 and Dc3 232–239 μm; between Dc3 and Dc4 5–7 μm ( Fig. 4F ). Thoracic horn with multiple branches.

Abdomen ( Fig. 4G ). Tergites I with or without weak shagreen; tergites II–VI with anterior band of stronger shagreen and long median field of finer shagreen; tergites VII with fine anterior band of shagreen only. Tergite VIII with two lateral anterior patches of spinules. Conjunctive IV/V with large continuous band of dark strong spines. Sternites bare. Tergite II with 42–45 hooklets. Pedes spurii A and Pedes spurii B absent. Anal comb with strong apical tooth and 5–6 smaller accessory teeth. Genital sac overreaching anal lobe by 125 μm.

Abdominal setation. Segment I without L setae; segments II–VI with 3 non–taeniate apically rounded, L setae; segment VII with 3 non–taeniate apically rounded and 1 posterior LS seta; VIII with 4 taeniate L setae. Fringe of anal lobe with 68–80 taeniae in single row.

Larva. (n = 1). Total length not measurable. Head capsule 398 μm long. Postmentum 172 μm long.

Coloration. Head capsule light brown, teeth of mentum and mandible black.

Head. Head capsule slightly rounded. Antenna as in Figure 4C . Length of antennal segments (in μm): 47, 20, 10, 10, 5. Blade 37 μm long. AR 1.17. Lauterborn organs 2 μm long. Pecten epipharyngis ( Fig. 4B ) consisting of 3 platelets, median with 3 teeth; lateral each with 4 teeth. Mandible ( Fig. 4D ) 129 μm long with apical tooth and 3 inner teeth. Seta subdentalis 5 μm long; seta interna with about 25 branches. Mola with weak spines. Mentum ( Fig. 4A ) 110 μm wide, with 8 pairs of mental teeth. Ventromental plate 127 μm wide, with anteriorly produced median ends and without posterior projection, distance between plates 17 μm.

Abdomen. Missing.

Remarks. Adult males of Polypedilum (Asheum) curticaudatum and P. (A.) beckae differ from P. (A.) sofiae sp. n. by the stout gonocoxite and gonostylus and superior volsella with variably concave outer apical margin. However, P. (A.) curticaudatum and P. (A.) beckae are morphologically very similar and P. (A.) beckae can be identified by the boot shaped superior volsella with at most slightly concave outer apical margin (“boot sole”). Also, P. (A.) curticaudatum has wide L setae on pupal abdominal segments I–IV, as in Polypedilum (A.) sp. Amazon ( Pinder & Reiss, 1986) (all strongly narrowed basally in P. beckae ), and sometimes has shagreen on abdominal tergite I (in P. beckae it is absent). Larvae of P. (A.) curticaudatum and P. (A.) beckae are identical.

Distribution. The species is known from Brazilian Atlantic Forest, Pantanal and Caatinga biomes. The previous record was only from its type locality in the state of Paraíba ( Rempel, 1939) and now it is recorded from the states of Bahia, São Paulo, Santa Catarina and Mato Grosso do Sul ( Fig. 5 ).

Figures

FIGURE 3. Polypedilum (Asheum) curticaudatum Rempel, adult male (A–H) and Polypedilum (Asheum) beckae (Sublette, 1964), adult male (I–K). A, tergite IX and dorsal aspect of left gonocoxite and gonostylus. B, hypopygium with tergite IX removed, left dorsal aspect, right ventral aspect. C–H. Variation of superior volsella in P. curticaudatum [C and D, both from same specimen, Corumbá population; E, Fazzari population; F, Joaçaba population; G, Andaraí population; H, modified from Rempel (1939)]. I–K. Variation of superior volsella in P. beckae [I, modified from Cranston et al. (1989); J, Santo Domingo population; K, modified from Sublette (1964)]

FIGURE 4. Polypedilum (Asheum) curticaudatum Rempel, larva (A–D) and pupa (E–G). A, mentum and ventromental plates. B, labrum and frontoclypeal apotome. C, antenna. D, mandible. E, frontal apotome. F, cephalothorax. G, L seta on segment IV. H, abdominal tergites.

FIGURE 5. Distribution of Polypedilum (Asheum) in neotropical region.