Single Taxon Treatment New European records of Ditomyia macroptera Winnertz ( Diptera : Ditomyiidae ) with notes on its distribution

New records of Ditomyia macroptera Winnertz from Bulgaria and France are presented representing the second rearing event after its initial description. Illustrations of the general facies and male terminalia are given. The study of old collection material reveals exclusion of the species from the Belgian list and allows us to discuss the origin of two specimens in the collection of C.R. Osten-Sacken in St. Petersburg, Russia. ‡ §


Introduction
Ditomyiidae is a worldwide distributed family of Diptera, represented by nearly a hundred described species in 9 extant genera (cf.www.sciaroidea.info).Four species in two genera are known to occur in Europe.Both genera -Ditomyia Winnertz, 1846 and Symmerus Walker, 1848 -are represented by two species (Chandler 2004).Ditomyia fasciata (Meigen, 1818) is a widely distributed species in Europe, although not very common in samples and is also recorded from the Eastern Palaearctic (Zaitzev 1994, Chandler 2004).On the contrary, Ditomyia macroptera (Winnertz, 1852) is a Palaearctic species, exceptionally rare in Europe, so far known only by a relatively small number of specimens.Having been described by Winnertz (Winnertz 1852: 55) from a single female specimen collected in Aachen (Germany), the species is subsequently recorded from Poland (Mikołaczyk 1991), Germany (Zaitzev 1978), Czech and Slovak Republics (Ševčík 2004, Ševčík et al. 2005, Ševčík et al. 2013), Italian mainland (Dahl et al. 1995, Kurina 2008) and Belgium (Gosseries 1991).One male specimen has been also recorded by Okada (Okada 1936) from the Eastern Palaearctic: Sakhalin Island (but see discussion below).According to the original description D. macroptera was reared from Phellinus igniarius (Winnertz 1852: 55) and there have not been additional data on the biology of this species up to the present.The European congener -D.fasciata -is known from different bracket fungi but most frequently from Trametes versicolor (Jakovlev 1994), Bjerkandera adusta and Polyporus species (Ševčík 2010).
During recent years, new material has come into the authors' possession that initiated the current communication.Here we present the new country records from Bulgaria and France, along with comments on earlier ones resulting in changes in the distribution range of the species.

Materials and methods
The Bulgarian material (Fig. 1) is reared from fruiting bodies of Phellinus alni, which were collected in an old orchard in village of Ilindentsi, South Western part of the country.The French material was collected in the southwest of the Jura Mountain Range in France, on the French-Swiss border with Malaise traps in 2011, but only received for examination by PC in 2015.Samples from 12 Malaise traps at this site, operated from 2009 to 2011, produced 112 species of fungus gnats, but only two specimens of D. macroptera were present.The two traps involved were situated about 100 m apart in a historically drained bog area at 850 m altitude, at a site where Phellinus igniarius has been recorded; both specimens lack legs and the male lacks antennae.

Conservation
Due to its rarity, D. macroptera is considered as critically endangered (CR) in the Czech Republic (Ševčík 2005).

Biology
According to Landrock (Landrock 1940) the species is rare in the mountain forests of Central Europe.This species has only been reared from two very similar species of bracket fungi: Phellinus igniarius (Winnertz 1852) and Ph.alni (original data).

Discussion
The type of D. macroptera is probably destroyed, like most of the material collected by J. Winnertz, when it was stored in Poppelsdorf Castle near Bonn (Germany) during World War II (Evenhuis 1997).Some of Winnertz' Diptera types have, however, survived in the Senckenberg Museum of Natural History, Frankfurt a. M., Germany (cf.Plassmann 1970) and in the Natural History Museum Vienna, Austria (cf.http://www.nhm-wien.ac.at/en/ museum) but D. macroptera is not listed.Zaitzev (Zaitzev 1994: 35) characterised the species according to one male and one female specimen from the collection of C.R. Osten-Sacken in ZIN (Zoological Institute, Russian Academy of Sciences, St. Petersburg), with a note that the collecting locality for them was unknown but with a collecting date as early as 11.v.1835 (i.e. 17 years before the description of the species).At present, the collection of Osten-Sacken housed in ZIN includes one male specimen (Fig. 3) with a label "L.Vindib."but without collecting date included (A.Przhiboro pers.comm.).We are not aware of the location of the female specimen that is (was) apparently supplied also with the date label mentioned by Zaitzev (Zaitzev 1994: 35).The specimens of D. macroptera in the collection of Osten-Sacken were probably acquired from the remains of the P.   Gent, 11.vii.1929, M. Goetghebuer leg.) in the collection of RBINS [Royal Belgian Institute of Natural Sciences, Brussels] that proved to be, after thorough recent studies, Symmerus annulatus (Meigen, 1830).Consequently, the distribution range of D. macroptera should be restricted to exclude Belgium.
We were not able to study the single specimen from the Eastern Palaearctic (Okada 1936) and the record remains questionable.At the time when Okada studied the specimen, there were neither detailed description nor figures of male or female terminalia of D. macroptera available.Subsequently, five additional Ditomyia species were described from the Eastern Palaearctic.Three of them, viz.D. claripennis Saigusa, 1973, D. spinifera Zaitzev, 1978and D. insularis Zaitzev, 1994, have been discussed as resembling D. macroptera (Saigusa 1973, Zaitzev 1978, Zaitzev 1994).The record of D. macroptera from Sakhalin Island was questioned also by Zaitzev (Zaitzev 1994).
Our records are from European mountain areas that corroborate earlier characterisation on habitat requirements of the species (e.g.Landrock 1940).The Bulgarian record, in addition to being the southernmost so far, also represents the second record of its larval host after one and half centuries.
The material is deposited in following institutional and private collections: IZBE -Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences [former Institute of Zoology and Botany], Tartu, Estonia; CPCM -Collection of Peter Chandler, Melksham, U.K.
C. Zeller collection after 1876, when C.R. Osten-Sacken returned to Europe (cf.Osten-Sacken 1903: 9-10).However, the label is different from most of those under specimens collected by Zeller (A.Pont pers.comm.).Otherwise, Horn et al. (Horn et al. 1990: Plate 5, fig.27) provided a handwritten label by Zeller with "Mus.Vindob." on it, representing the Vienna Museum.At the present stage of knowledge, we are not able to clarify the mystery of two specimens in the Osten-Sacken collection, but with a high probability, they have been collected in Central Europe.