Polypedilum (Pentapedilum) acristylum, Yamamoto, Nao, Hirowatari, Toshiya & Yamamoto, Masaru, 2012

Yamamoto, Nao, Hirowatari, Toshiya & Yamamoto, Masaru, 2012, The subgenus Pentapedilum Kieffer (Diptera: Chironomidae) in the Yaeyama Islands, the Ryukyus, Japan, Zootaxa 3191, pp. 33-40 : 34-35

Polypedilum (Pentapedilum) acristylum sp. nov.

( Figs. 1–6 )

Type material. Holotype male. JAPAN: Funaura, Iriomote Island, Okinawa, 22.III.2000, sweep net, M. Yamamoto (No. OPU–NY59); Paratypes. JAPAN: Ootomi, Iriomote Island, Okinawa, 5.VII.1982, 1 male, light trap, K. Ohara (No. OPU–NY53); as holotype, 1 male (No. OPU–NY12)

Diagnostic characters. In the male, the strongly haired wing membrane, uniformly colored abdomen and lack of microtrichia on the base of the superior volsella, make the species closely similar to P. (Pe.) nodosum Johannsen, 1932 . However, it is distinguished from the latter by the projection of the superior volsella with 1–2 basally placed lateral setae and a wide gonostylus with the acute apex.

Etymology. From the Latin acristylum , referring to the acute apex of the gonostylus.

Description. Male (n = 3, unless otherwise stated)

Total length 2.3 (1) mm. Wing length 1.55–1.7 (2) mm. Total length / wing length 1.35 (1). Wing length / length of profemur 3.33 (1).

Coloration. Head yellowish brown, thorax dark brown, abdomen pale brown, femur, tibia and tarsi yellowish brown.

Head. AR 0.53–0.59 (2). Ultimate flagellomere 490–600 (2) μm long. Rest broken.

Thorax ( Fig. 1 ). Acrostichals 9–10 (2), dorsocentrals 13 (2), prealars 3 (2), scutellars 9 (2).

Wing ( Fig. 2 ). Anal lobe reduced. VR 1.11–1.17 (2). Brachiolum with 1 (1) seta, R with 17–27, R1 with 19–29, R4+5 with 39–48, M with 7–12, RM with 0, M1+2 with 44–63, M3+4 with 24–28, Cu with 20–40, Cu1 with 14–23, An with 31–39 setae. Cell m basal of RM, r4+5, m1+2, m3+4 and cu plus an each with more than 50 macrotrichia. Squama with 9 (1) setae.

Legs ( Fig. 3 ). Scale on fore tibia 30–48 μm long, without long apical spur. Spurs on mid tibia 38–58 μm long, on hind tibia 35–55 μm long. Width at apex of foretibia 47–55 μm, of mid tibia 44–53 μm, of hind tibia 48–55 μm. Length and proportions of legs as in Table.

Hypopygium ( Figs. 4–6 ). Tergite IX with 5–6 (2) median setae, laterosternite IX with 1–2 (2) setae. Anal point 40–45 (2) μm long, 3–4 (2) μm wide at base, nearly parallel-sided, gradually tapering to pointed apex. Transverse sternapodeme 40–43 (2) μm long, phallapodome 80–95 (2) μm long. Gonocoxite 105–131 μm long. Total length of superior volsella 43–70 μm, base bare with 2 inner setae, projection apically slender, elongated and slightly curved. Inferior volsella 80–165 μm long, slightly curved and clavate with prominent apical seta. Gonostylus 85–123 μm long. HR 1.28–1.29 (2), HV 2.24 (1).

Remarks. The species was collected in open ground near the edge of evergreen forest around Kanpira-falls in Iriomote Island in the Yaeyama Islands, the Ryukyus, Japan (subtropical region).

TABLE Length (in μm) and proportions of legs of Polypedilum (Pentapedilum) acristylum sp. n., male (n=3).

fe ti ta1 ta2 ta3 ta4 ta5 LR

p1 450–850 440–520 1050 (1) 760 (1) 460 (1) 350 (1) 160 (1) 2.02 (1) p2 640–850 570–765 365 (1) 215 (1) 135 (1) 90 (1) 60 (1) 0.64 (1) p3 740–900 680–780 530–770 (2) 270–340 (2) 230–310 (2) 150–210 (2) 70–110 (2) 0.78–0.99

Figures

FIGURES 1 – 6. Adult male of Polypedilum (Pentapedilum) acristylum sp. nov. 1: thorax, lateral view; 2: wing; 3: scale of fore tibia; 4: genitalia, dorsal view; 5: genitalia, lateral view; 6: superior volsella.