Acomopterella martinovskyi

Male. Head. Fig. 4. Head capsule, labella and antennae brown, palpi yellow. With three ocelli in a broad triangle. Median ocellus slightly smaller than the lateral ones. The median ocellus is surrounded by the medioocellar suture, with narrow pseudosclerite above ocellus. Lateral ocelli less than two times its own diameter distant from eye margin. Compound eyes covered with interommatidial setulae, with only some few blank interommatidial spaces near the dorsal eye margin. Ommatidia densely arranged. Basal palpomere distinct, ventrally extended, covering palpomere 2 for some distance. Second palpomere quite small, with 1–2 minute setae. Third palpomere with numerous sensilla claviformis that are evenly dispersed over the basal 3/4 of the inner surface of palpomere 3 (Fig. 8), a few setae situated mainly apically. Palpomeres 4 and 5 loosely scattered with similar setae, as present in the preceding segment. Scape and pedicel with few stronger setae, flagellomeres 1–3 with few small setae dorsally. Flagellomeres cylindrical, with trichia not reaching the length of a flagellomere diameter (Fig. 5). The antennal flagellomeres are sparsely scattered with sensilla chaetica (Figs 5, 7), 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 with 4–6, clypeus with several more setae. The premental apodeme is small, its posterior part weakly sclerotized and hardly traceable. Thorax. Fig. 10. Uniformly brown. Scutum shining, dome shaped, with long erect acrostichal, dorsocentral and lateral setae. Antepronotum with 2 large and a further few tiny setae, proepisternum with 1-2 large setae and a few tiny setae. Meso- and metapleuron, laterotergite and mediotergite bare. Scutellum with 2 strong and several smaller setae. Wing. Fig. 2. Length 3.8-4.7 mm. Wing index 2.6. Wings clear, membrane with microtrichia only. Subcosta ending at level of base of ta in R, or shorter. Radial veins, M1, M2, M4 and CuA setose on the dorsal surface, R1 ventrally setose at tip. Other veins bare. Stem of median fork long, about 0.16 times wing length. The position of vein R4 is slightly variable, depending its distance from Rs. Vein R5 a little downcurved apically, costa exceeding its tip for one third of its distance to M1. M4 long, visible far before level of ta-base, basally detached. 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 4 ventral, 3 posterior, 2 posterodorsal, 1 dorsal, 6-7 anterodorsal and 10 anterior setae, the posterodorsals as long as tibial width, the other are shorter than tibial width. Mid tibia with 3 ventral, 3 anterior, 3 dorsal and 5-7 posterior setae, all of them shorter than tibial width. Fore tibia with 3 dorsal and 4 posterior setae. Mid tibia slightly swollen at its base, with an elongated patch of specialized seta chaetica (Figs 33-34). The single setum chaeticum has 7-9 filamentous branches, subequal in length and width. Hind tibia without apical comb. Tibial spurs 1:2:2, mid and hind spurs longer than tibial width. Empodium of normal size (Fig. 12). Fore basitarsus 1.1 times longer than tibia. Abdomen. All abdominal segments including terminalia brown, with pale hairs. Segments 2–5 long, 6 and 7 a little shorter. Tergite 8 vestigial (Fig. 17) and completely retracted, sternite 8 reduced in width, partly retracted. Terminalia. Figs 14–20. Tergite 9 medium sized, twice as broad as long, together with cerci covering 3/4 of the gonocoxites. Gonocoxites ventrally widely separated, having only a narrow basal sclerotized connection. Parameres long, hardly reaching gonocoxal apex. Gonostylus medium sized, about half as long as gonocoxite, very slightly (Europe) to double bent (Far East) and simply tapered. European specimens have the gonostylus slightly shorter, maybe reaching 1/3 of gonocoxite length. Cerci with strikingly dense, long hairs, which are directed proximad. Hypoproct weakly sclerotized, horseshoe-shaped, with two strong apical setae (Fig. 16). Female. Head. Antenna reaching 3rd abdominal segment. Legs. Front tarsi unmodified, except for the prolonged basitarsus. No mid tibial organ present. Terminalia. Gonocoxite 8 widely rounded, with a couple of distad directed apical setae (Fig. 13). Tergites 9 & 10 sparsely setose. Cerci setose, basicercus twice as long as disticercus. Cerci directed ventrad. Egg. A single egg is 410 µm long and 135 µm in diameter. The dorsal and lateral parts of the eggshell are characterized by indistinct longitudinal rows of rosette-like, hexagonally arranged superficial layers, reaching the posterior pole (Fig. 21). The dorsal and lateral surface is described best as being irregularly rough and sharp-edged (Fig. 25). The micropyle is distinct, its surrounding area with 10-20 isolated plugs (Fig. 22). The lateral transition zone has the hexagonal structures gradually suppressed. The ventral surface is more flattened and rugose (Fig. 21), with a central plate of differing structure. The ventral plate has a rounded outline and is distinguished by dense-set, simple to three-pieced upright columns (Figs 23, 24). The egg of Acomopterella martinovskyi is distinct from that of other fungus gnat species by its rough dorsal and lateral surface. It resembles other species in the general structure of the micropylar area, the flattened bottom and the presence of a ventral plate. The structure of a ventral plate on Mycetophilidae eggshells was described by Mazzini et al. (1992, p. 34) for the first time, in 3 Mycomya species.

Acomopterella martinovskyi is known from several localities in the Czech Republic, from the Tyrolean Alps (Austria), the Bavarian Alps (Germany), from Sweden (Kjaerandsen 2012), from Sakhalin (Russia) and Hokkaido (Japan).