Bradysia polonica (Lengersdorf, 1929)

Babytskiy, A. I., Bezsmertna, O. O., Moroz, M. S., Pavliuk, S. D. & Honcharenko, B. V., 2020, New Records Of Bradysia Species (Diptera, Sciaridae) From Ukraine, Zoodiversity 54 (4), pp. 329-340 : 337-339

Bradysia polonica (Lengersdorf, 1929) ( figs 38–46 )

= Bradysia edwardsi Freeman, 1983

Scale bars: 0.10 mm.

M a t e r i a l e x a m i n e d. Ukraine, Ternopil Region, outskirts of Mykulyntsi, the right bank of Seret River, 49.403088 N, 25.608273 E, ca. 280 m a. s. l., coastal overgrowth of adventive synanthrops ( Acer tataricum L., Humulus lupulus L., Urtica dioica L.), collected with aspirator, 28.06.2014, 2 {, leg. A. Babytskiy (No. 27-8); Ukraine, Ternopil Region, outskirts of Stinka, the left bank of Dniester River, Dniester Canyon National Nature Park: 48.91482 N, 025.23508 E, ca. 200 m a. s. l., coastal beech-hornbeam forest, sweeping, 09.08.2016, 1 {, leg. A. Babytskiy (No. 75, UkrBIN-795797).

D i s t r i b u t i o n: Austria, Bulgaria, Czech Republic, Finland, Germany, Hungary, Ireland, Italy (mainland), Poland, Romania, Sweden, Switzerland, The Netherlands, United Kingdom ( Menzel et al., 2006; Menzel & Heller, 2013), Kazakhstan ( Sataeva, 2006), Ukraine (first record).

Diagnosis. Male imagoes reach 2 mm in length. Eye bridge narrow, consists of 2 facet rows ( fig. 43 ). Flagellum, halter and hypopygium brown, legs, necks of the flagellomeres and stalks of the halter yellow-brown. Maxillary palp rather short, consists of 3 palpomeres, all segments subequal or p 3 slightly elongated; no dark sensory area on p 1 ( fig. 46 ). The length/width of the 4 th flagellomere 2.5–3 ( fig. 44 ). Thorax black-brown; setae blackish and not contrasting with dark body ( fig. 38 ). Femur 3 5 / 6 of tibia 3. Wing length 1.8–2.0 mm; all veins wide, anterior ones well recognizable, posterior – somewhat vaguely limited; R 1 short, falling into C well before the base of M-fork; R 5 falling into C well before the end of M 2, the distance between the ends of R 5 and M 1 large and approximately equal to distances M 2 –Cu 1 and Cu 1 –Cu 2; the length of stM approximately equal to the length of M-fork; M 1 and M 2 run almost parallel, M 2 weak S-shaped curved, M 1 slightly bent; stCuA slightly longer than x, in distal part both run almost parallel, in proximal part converge; c/w = 0.6 ( fig. 45 ). The knob of the halter longer than the stalk, with long and short setae. Hypopygium with tapered basal lobe ( fig. 39 ); basal lobe highly sclerotized, with strong setae as a crest at apex, some fine setae laterally ( fig. 42 ). Gonostylus with notch in distal part, very short apical tooth and 2 equal subapical spines ( fig. 41 ) ( Lengersdorf, 1928 –1930; Gerbachevskaja, 1969; Freeman, 1983).

Bradysia polonica belongs to the B. polonica group, which contains only 6 Holarctic species, differing from the other Bradysia species by the presence of the basal lobe on ventral base of genitalia, gonostylus without apical tooth, tegmen widely rounded with circular area of fine teeth, and sensory area on basal palpomere simple or with weak margin ( Menzel & Mohrig, 2000). Bradysia polonica is characterized by the wide, somewhat indistinctly limited posterior wing veins. Tuomikoski (1960) suggested that such a wing structure can be connected with reduction of flight capacity. He indicated similar wing venation of other small Bradysia species. The most similar to B. polonica are B. rectinervis Frey, 1948 and B. crassinervis Frey, 1948 , both of which belong to the B. angustipennis group. Bradysia rectinervis differs from B. polonica by the wider (3-row) eye bridge, and B. crassinervis by the remarkably thick anterior veins, of which R 5 is almost straight (weakly but clearly curved in B. polonica ) ( Tuomikoski, 1960). Also the male of B. polonica is easily recognizable by the structure of the gonostylus and can also be separated from both species by the structure of sensory area on basal palpomere that distinguish species of B. polonica group (undifferentiated sensory area) from species of B. angustipennis (distinctly margined) ( Menzel & Mohrig, 2000). Moreover, the description of B. crassinervis was based on a female and this species is a nomen dubium that cannot be recognized with modern keys based mostly on male genitalia characters. In gonostylus structure, B. polonica resembles B. strigata (Staeger, 1840) , but differs by much bulkier gonostylus, with a thicker, stronger, shorter tooth and two subsidiary spines ( Freeman, 1983).

Note. Studied male imagoes reach ca. 2.0 mm in length, wing is 1.6–1.8 mm in length and 0.7 mm in width; y naked or bears 1 mesial macrotrichia. Tibial organs of t 1 in present specimens consist of 5 bristles in a comb-like row ( fig. 40 ). Biometric indexes of studied specimens: width/length of wing = 0.39–0.40; stM/M-fork = 0.89–1.04; R 1 /R = 0.45–0.51; x/y = 0.94–1.45; stCuA/x = 0.86–1.07; c/w = 0.63–0.67. Length of spur/width of tibia: leg 1 = 1.06–1.34, leg 2 = 1.06–1.37; leg 3 = 1.23–1.48. Length of metatarsus/length of tibia: leg 1 = 0.51–0.59, leg 2 = 0.49–0.55, leg 3 = 0.48–0.55. Length of tibia 3/length of thorax 1.09–1.18.

We consider it our pleasant obligation to express sincere gratitude to our colleagues and friends, who supported our work, among them, Valery Korneyev (I. I. Schmalhausen Institute of Zoology, NAS of Ukraine, Kyiv, Ukraine) for his ongoing help, scientific guidance and valuable advice, and Frank Menzel (Senckenberg Deutsches Entomologisches Institut, Müncheberg, Germany) for his kind help in identification of the specimens. Special thanks are due to Igor S. Kvach, the director of the Kivertsi National Park “Tsumanska Pushcha” (Kivertsi), for his permission and assistance in carrying out expeditions in the park. We also thank two anonymous reviewers for their valuable comments.

Figures

Figs 38–46. Bradysia polonica, male: 38 — thorax, lateral view; 39 — hypopygium, ventral view; 40 — anterior apex of fore tibia (t 1) with tibial organ, lateral view; 41 — gonostyli, ventral view; 42 — base of hypopygium with basal lobe, ventral view; 43 — eye bridge, frontal view; 44 — fourth flagellomere, lateral view; 45 — wing, dorsal view; 46 — maxillary palp, lateral view.