Polypedilum (Pentapedilum) shirokanense Sasa

Oyewo, Emmanuel Adeoye & Saether, Ole A., 2008, Revision of Polypedilum (Pentapedilum) Kieffer and Ainuyusurika Sasa et Shirasaki (Diptera: Chironomidae), Zootaxa 1953, pp. 1-145 : 97-99

Polypedilum (Pentapedilum) shirokanense Sasa

( Fig. 32)

Polypedilum (Pentapedilum) shirokanensis Sasa, 1979: 10 .

The type supposedly in the Sasa collection is missing. The species was described in detail by Sasa (1979).

Diagnostic characters. Among species with less than 100 setae in each of cells m 1+2 and r 4+5, foretibial scale without spur, and base of superior volsella with microtrichia and 4–6 inner setae, the species is distinguished by having the setae of the projection of the superior volsella placed medially and the base completely covered by microtrichia. The species is quite similar to P. (Pe.) kamosecundum , which, however, has a less microtrichiose base of the superior volsella, a more basally placed lateral seta of the projection, inner margin of projection rugulose, and a small V-shaped ridge at the base of the anal point. The pupa has median shagreen on tergite II and some shagreen on tergite VII, conjunctive III/IV with spinules, and apparently reduced pedes spurii B. The larva has a mandible with dorsal tooth, median teeth of mentum slightly longer than or subequal to second lateral teeth, third antennal segment slightly longer than fourth, and antennal blade shorter than flagellum and reaching base of fifth segment.

Male (from Sasa 1979)

Total length 2.6–2.8 mm. Wing length 1.68–1.95 mm. Thorax yellow with brown vittae; abdominal segments almost uniformly dark brown; femur, tibia and tarsi brown.

Head. AR 1.43–1.57. Temporal setae 8. Clypeus with 16 setae. Palpomere 2–5 lengths (in µm): 53, 113, 116, 188.

Thorax ( Sasa 1979, fig.16B). Acrostichals 10, dorsocentrals 14, prealars 5. Scutellum with 8 setae.

Wing ( Sasa 1979, fig.17F). Anal lobe weak. Cell m basal of RM apparently bare. Squama with 6–8 setae.

Legs ( Sasa 1979, fig.16D–E). Scale on foretibia without spur. LR 1 1.7–1.8.

Hypopygium ( Fig. 32A; Sasa 1979, fig.17A–E). Tergite IX with 8–9 median setae. Anal point 58 µm long, 10 µm wide, parallel-sided. Base of superior volsella ( Fig. 32 B) covered with microtrichia, with 5 inner setae, projection with 1 seta. Inferior volsella about 120 µm long; parallel-sided with prominent apical seta.

Female (from Sasa 1979)

Total length 1.6–2.3 mm. Wing length 1.68–2.11 mm. Coloration as in male.

Head ( Sasa, 1979, fig.16A). Antenna as in Sasa (1979, fig.16C). Lengths of antennal segments (in µm): 67, 137, 92, 96, 161. Temporal setae 8. Palpomere 2–5 lengths (in µm): 53, 123, 133, 227.

Thorax. Scutellum with 10 setae.

Wing ( Sasa 1979, fig.17F). Anal lobe weak. Squama with 3 setae.

Legs. Scale on foretibia without spur. LR 1 1.8–1.9.

Genitalia. Cercus as in Sasa (1979, fig.16G). Seminal capsules as in Sasa (1979, fig.16F).

Pupa (from Sasa 1979)

Total length 3.5–3.9 mm. Frontal seta, cephalothorax, margins of segments and caudolateral spur brown.

Cephalothorax ( Sasa 1979, fig. 18 A). Thoracic horn with 7 branches ( Sasa 1979, fig. 17G).

Abdomen ( Fig. 32C; Sasa 1979, fig. 18B–C). Tergite I bare, tergites II–VI each with strong, prominent anterior row of spines; tergite II and III with few weak and sparse or occasionally extensive medial shagreen; tergites II and III each with median band of spinules, tergite IV with two median patches, tergite V with single median patch and two posterior patches of spinules, tergite VI with two median patches and two posterior patches of spinules, tergite VII with paired anterolateral spots of spinules, tergite VIII bare. Tergites VII and VIII both without additional shagreen. Conjunctives III/IV and IV/V with multiserial band of anterior pointed spinules. Tergite II apparently with mostly single row of more than 40 caudal hooks. Pedes spurii A present on segment IV. Pedes spurii B weakly developed on segment II. Caudolateral spur 105–176, 134 µm long, with 1 strong apical tooth, 2–4 lateral teeth and several accessory points. Segments I–IV without L taeniae, V and VI with 3 taeniae; VII and VIII with 4 taeniae. Anal lobe fringe with about 40 taeniae.

Larva (from Sasa 1979)

Total length 5.11–5.47, 5.23 mm.

Head. AR about 1.1. Antenna as in Fig. 32D ( Sasa 1979, fig. 19C), lengths of segments (in µm): 60, 19, 15, 14, 6. Blade 51 µm long, shorter than flagellum. Premandible, mandible ( Fig. 32E), mentum ( Fig. 32F), and epipharyngeal area as illustrated by Sasa (1979, fig. 19).

Abdomen. Procercus with 8 anal setae. Anal tubules 120–165 µm long.

Remarks. The species could possibly be a senior synonym of P. (Pe.) kamosecundum .

Distribution. Known only from Japan.