Trichocera (Metatrichocera) unica Kolcsár, 2018

Kolcsár, Levente-Péter, Petrašiūnas, Andrius, Török, Edina & Keresztes, Lujza, 2018, A new species of Trichocera Meigen with further records of Metatrichocera Dahl from Bulgaria, Romania, and Serbia (Diptera, Trichoceridae), Turkish Journal of Zoology 42 (2), pp. 172-178 : 173-175

3.1. Description of Trichocera (Metatrichocera) unica Kolcsár , sp. nov.

Since the specimens described herein ( Figures 1–3) are stored in alcohol, their actual coloration might differ from the specimen stored dry or observed alive.

Diagnosis: Medium-sized species, with relatively simple gonostylus, which is cylindrical in general, with a rounded projection on the interior margin in the middle, the apical end of gonostylus yellowish and finger-like. Gonocoxite cylindrical in dorsal view and the bridge distinctly fused and bent apically, leaving a large rhombus-shaped membranous area over sternite IX in ventral view.

Material: Holotype: male, Bulgaria, Kalòfer (КалÒфер), Stara Planina Mts., tributary of the Tùndzha River (Тунджа река), 900 m, 42.669285°N, 24.987644°E, 28 October 2016, leg. Kolcsár L.- P. and Török E.

Paratypes: 3 males and 2 females from same location and date , 3 males from Bulgaria, Turiya / Turia (Турия), Sredna Gora Mts., Turiiska River (Турийска река), 620 m, 42.51086°N, 25.20612°E, 30 October 2016, leg. Keresztes L .

Description: Male: Body 5–5.1 mm, wing 6–6.1 mm. Head dark brown. Antennae lighter brown than the head, 16-segmented, 2.5–2.8 mm long. Scape and pedicel a little darker than the remaining flagellomeres. First flagellomere (f1) elongated, 1.2–1.5 times as long as the second one (f2) ( Figure 1C). Flagellomeres 2–4 are equal in length, f5–f6 are a little narrower and longer than f4. Starting from f7 and up to f14 the flagellomeres are very narrow and are approximately equal in length ( Figure 1D).

Thorax light brown to brown. Legs are unicolored, light brown. Fore fourth tarsomere 1.1× longer than the fifth tarsomere. Fore fifth tarsomere 3.5–4× as long as the tarsal claw ( Figure 1B). Half of the fifth tarsomere is densely covered with setae on the ventral side ( Figure 1B). Wing venation light brown to brown. A 2, cross-veins r-m and m-cu and the basal 1/3 of the M are bare, all other veins with setae on both sides. Stigma is very faint, a small spot is visible on r-m ( Figure 1A).

Abdomen brown to dark brown. Male genitalia dark brown. Sternite IX and tergite IX fused ( Figures 2E, 2F ). Gonocoxite cylindrical in dorsal view ( Figures 2A, 2B ). The bridge distinctly bent apically and fused in middle, leaving a large rhombus-shaped membranous area over sternite IX in ventral view ( Figures 2C, 2D ). Gonostylus is uniquely shaped within the Trichoceridae . Gonostylus is cylindrical in general, with a small rounded projection on the interior margin in the middle ( Figures 2A–2D ), with a finger-like narrowing at the end. The finger-like end of the gonostylus is yellowish, with the end covered with setae ( Figure 2G ). In lateral view the gonostylus is mildly curved ventrally ( Figures 2E, 2F ). Aedeagal complex ( Figures 1F, 1G).

Female. Body 5.1–5.2 mm, wing 5.9–6.1 mm. Female antennae are similar to male antennae, just a little shorter (2.2–2.5 mm). Body coloration is similar to the male body coloration. Wing as in the case of male. Female genitalia light brown ( Figure 3 ). Tergites 9 and 10 fused in middle ( Figure 3B ). Cercus (ovipositor) is 0.5 mm long, as long as the genital segment (tergites 8–10 and sternite 8) ( Figures 3A, 3B ). The inner side of the cercus is covered in spikelike setae that are directed apically and probably help the egg-laying ( Figure 3H ). The tip of cercus is rounded and bears two larger sensilla and a row of smaller ones along the edge ( Figure 3I ). Genital plate is slightly broadened in the middle part ( Figure 3E ). Supragenital plate is narrow in the basal part, forming a concave surfaces and bears two bristles ( Figure 3E ). Genital fork is 1.8× longer than the genital plate ( Figure 3E ). The three spermathecal capsules are rounded ( Figure 3F ). Hypogynial valves are rounded both in lateral and ventral view, with small lobes in dorsal parts ( Figures 3A, 3C, 3D ).

Distribution and ecology: The new species is probably widely distributed in the Stara Planina Mountains and in the surrounding areas. The species was collected by us around small brooks in hornbeam ( Carpinus betulus )- dominated forest. The specimens were collected in temperatures between 1 and 5 °C.

Notes: The species is unique and has relatively simple genitalia within Metatrichocera , probably representing a new species group. We include the species in Metatrichocera based on the relatively narrow anal cell, the gonostylus being not simply shaped and the gonocoxal bridge distinctly bent apically and fused in the middle. However, the new species does not match all the features of Metatrichocera highlighted by Krzemińska (2002), as the gonocoxite is cylindrical, longer than wider in dorsal view, the membranous part between the bridge and IX sternite is large and the lateral apodemes of aedeagal complex are relatively dumpy, not three times longer than wide. Until a more thorough revision of subgenus Metatrichocera is made, we include the species in this subgenus.

Etymology: The name of the species refers to its uniquely shaped gonostylus (unica = unique).

Figures

Figure 2. Trichocera (Metatrichocera) unica Kolcsár, sp. nov. male genitalia. Dorsal view: A- photograph; B- schematic illustration, ventral view; C- photograph; D- schematic illustration. Lateral view: E- photograph; F- schematic illustration; G- close view of apical part of gonostylus. Scale bars: A–F- 0.5 mm.

Figure 3. Trichocera (Metatrichocera) unica Kolcsár, sp. nov. female genitalia: A- lateral view; B- dorsal view; C- ventral view; D- close lateral view of female genitalia; E- inner genitalia in ventral view; F- spermathecal capsule; H- pattern in the inner side of cercus; Ipattern in the end of cercus. Scale bars: A- 0.5 mm, B and C- 0.25 mm, E and F- 0.2 mm.