Acomopterella yoshiwae Kallweit

Kallweit, Uwe, 2013, Review of the Palaearctic Acomopterella Zaitzev (Diptera, Sciaroidea, Mycetophilidae), ZooKeys 269, pp. 11-32 : 15-17

Acomopterella yoshiwae Kallweit sp.n. Figs 3, 6, 9, 26-30, 31-32

Diagnosis.

The species is characterized by a peculiar extended fore basistarsus, which is 1.5 times as long as the fore tibia. A strong basalization of radial veins has led to the nearly horizontal crossvein ta and foreshortened R1. C extending beyond apex of R5 for 1/3 distance to M1. Subcosta ending a short distance before base of ta in R. Crossvein ta not reaching the length of M-stem. A single setum chaeticum of the mid tibial organ has 2 filamentous branches (Fig. 32). Empodium well developed. The gonostylus of Acomopterella yoshiwae consists of two completely separated lobes (Figs 26-27). Gonocoxites ventrally separated, having only a narrow basal sclerotized connection. Cerci small, with few apical setae (Fig. 28).

Description.

Male. Head. Head capsule, labella and antennae brown, palpi yellow. With three ocelli in a broad triangle. Median ocellus half the diameter of the lateral ones. Median ocellus surrounded by the medioocellar suture, with a narrow pseudosclerite above the ocellus. Lateral ocelli nearly contiguous to eye margin. Compound eyes covered with interommatidial setulae, with only some few blank interommatidial spaces near the dorsal eye margin. Ommatidia densely arranged. Palpi as in Acomopterella martinovskyi . Scape and pedicel with few stronger setae, flagellomeres without setae. Flagellomeres cylindrical, with trichia not reaching the length of a flagellomere diame ter (Fig. 6). The antennal flagellomeres are sparsely scattered with sensilla chaetica (Fig. 6), with a decreasing number of sensilla towards the tip of the flagellum. The antennal surface between the described vestiture is smooth. Antenna reaching 4th abdominal segment. Face and clypeus far-reaching fused, with few setae. The premental apodeme is small, posterior part weakly sclerotized and hardly traceable.

Thorax.Fig. 9. Uniformly brown. Scutum rather flattened; with pale, long erect acrostichal, dorsocentral and lateral setae. Antepronotum with 2 large and a further few tiny setae, proepisternum with 1 medium sized seta and few tiny setae. Meso- and metapleuron, laterotergite and mediotergite bare. Scutellum with 2 strong and several smaller setae.

Wing.Fig. 3. Length 4.3 mm. Wing index 2.7. Wings clear, membrane with microtrichia only. Subcosta ending a short distance before base of ta in R. Radial veins, M1, M2, M4 and CuA setose on the dorsal surface, other veins including basal part of CuA bare. Stem of median fork long, about 0.16 times wing length. Length of radial cell 3 times its own width. Vein R5 a little downcurved apically, costa exceeding its tip for 1/3 distance to M1. M4 meets CuA nearly exactly below base of ta. Haltere yellow.

Legs. Entirely pale brown. Hind coxae on its posterior ridge with a row of setae. Tibial and tarsal trichiae irregularly arranged. Hind tibiae with 5-7 tiny posteroventral setae in apical half, 6 posterior and 6 anterior setae. Mid tibia with 4 anterior, 4 antero dorsal, 2 posterior and 3 posteroventral setae. Fore tibia with 1 ventral seta. All tibial setae are shorter than tibial width. Mid tibia slightly swollen at its base, with an elongated patch of specialized seta chaetica (Figs 31-32, Table 1). The single setum chaeticum has 2 filamentous branches, subequal in length and width. Hind tibia without apical comb. Tibial spurs 1:2:2, subequal in length. Empodium of normal size, similar to that of Acomopterella martinovskyi . Fore basitarsus 1.5 times longer than tibia.

Abdomen. All abdominal segments including terminalia brown, with pale hairs. Segments 2-6 long, segment 7 little shorter. Tergite 8 vestigial and completely retracted, sternite 8 reduced in width, partly retracted. Terminalia.Figs 26-30. Tergite 9 medium sized, square, together with cerci covering half of the gonocoxites. Gonocoxites ventrally separated, having only a narrow basal sclerotized connection, which possibly represents the remainder of sternite 9. Parameres short, apically rounded. The gonostylus consists of two, completely separated lobes. The dorsal lobus is stout, strongly sclerotized and directed posterad. The ventral lobus is slender, less sclerotized, multicuspidate and directed ventrad. Cerci small, with few apical setae. Hypoproct weakly sclerotized, with two strong apical setae.

Female unknown.

Distribution and phenology.

Acomopterella yoshiwae sp. n. was collected from an old-growth deciduous / coniferous forest at Mt. Kanmuri on the island of Honshu.

Etymology.

The name refers to the origin of this species from Yoshiwa Village, Hiroshima Pref., Honshu, Japan.

Holotype.

male (on slide), Japan, Honshu, Hiroshima Pref., Yoshiwa Village, Mt. Kanmuri; mature mixed deciduous / coniferous forest; 1000 m; 28 Sep.-22 Oct. 1999; Malaise trap; collector M. Jaschhof (SNSD).

Key to species of Acomopterella , imagines only