Aquatic dance flies (Diptera, Empididae, Clinocerinae and Hemerodromiinae) of Greece: species richness, distribution and description of five new species

Abstract All records of aquatic dance flies (37 species in subfamily Clinocerinae and 10 species in subfamily Hemerodromiinae) from the territory of Greece are summarized, including previously unpublished data and data on five newly described species (Chelifera horvati Ivković & Sinclair, sp. n., Wiedemannia iphigeniae Ivković & Sinclair, sp. n., W. ljerkae Ivković & Sinclair, sp. n., W. nebulosa Ivković & Sinclair, sp. n. and W. pseudoberthelemyi Ivković & Sinclair, sp. n.). The new species are described and illustrated, the male terminalia of Clinocera megalatlantica (Vaillant) are illustrated and the distributions of all species within Greece are listed. The aquatic Empididae fauna of Greece consists of 47 species, with the following described species reported for the first time: Chelifera angusta Collin, Hemerodromia melangyna Collin, Clinocera megalatlantica, Kowarzia plectrum (Mik), Phaeobalia dimidiata (Loew), W. (Chamaedipsia) beckeri (Mik), W. (Philolutra) angelieri Vaillant and W. (P.) chvali Joost. A key to species of aquatic Empididae of Greece is provided for the first time. Information related to the European Ecoregions in which species were found is given. Compared to the other studied countries in the Balkans, the Greek species assemblage is most similar to that of the Former Yugoslav Republic of Macedonia.


Introduction
The aquatic dance flies of the family Empididae (Diptera) comprise the subfamilies Clinocerinae and Hemerodromiinae. Larvae mostly live in aquatic habitats and both larvae and adults are predators, primarily feeding on Simuliidae (Vaillant 1952, 1953, Werner and Pont 2003 and Chironomidae (Vaillant 1967, Harkrider 2000, Ivković et al. 2007. Adult Hemerodromiinae are distinguished by raptorial forelegs and live and hunt in riparian vegetation. On the other hand, adult Clinocerinae are primarily found on the surface of emergent wet stones or in moss mats (Wagner 1997, Ivković et al. 2007).
The aquatic dance fly fauna of Greece has been sporadically investigated during the last few decades. The first records were noted by Vaillant and Wagner (1990), Wagner ( , 1990Wagner ( , 1995, Wagner and Horvat (1993), and recently by Ivković et al. (2012).
Distribution and diversity studies are of immense importance in studying factors that influence and determine diversity hotspots Plant 2015, Schmidt-Kloiber et al. 2017). The present paper is based on detailed analysis of all publications on Greek aquatic dance flies known to the authors. The authors have also contributed additional records of Greek aquatic dance flies resulting from the examination of specimens collected by colleagues who surveyed 258 sites sampled in the late 1980s and early 1990s. In addition, one new species of Chelifera Macquart and four new species of Wiedemannia Zetterstedt are herein described.

Material and methods
Specimen records. This paper is based on a review of the literature, and primarily on unpublished data and specimens from Bogdan Horvat's study of the aquatic dance fly fauna of Greece. Wherever possible, each literature record and specimen record was georeferenced as precisely as possible using ArcGIS software. The names of taxa reflect current nomenclature and classifications (Sinclair 1995, Yang et al. 2007). The literature used for identifications included Engel (1939Engel ( , 1940, Vaillant and Wagner (1990), Wagner ( , 1990Wagner ( , 1995, Wagner and Horvat (1993) and Ivković et al. (2012). Locality records are listed for each species. A list of locality names including latitude, longitude, altitude and number codes (site ID) for the localities is presented in Table 1 and a map showing the locations of all the georeferenced sites is also provided (Fig. 1). Specimens were collected using sweep nets and by aspirator. They were preserved in 80% ethanol (EtOH). For the purpose of determination, male terminalia were dissected, boiled in 10% KOH and afterwards neutralized with acetic acid, rinsed in water and identified to species level; or they were macerated in hot 85% lactic acid and stored in 80% ethanol along with the remaining body parts in the same tube. In the genitalia illustrations, only the sockets of the setae are shown on the epandrium; the setae are not drawn. All specimens listed in the material examined sections were collected by Bogdan Horvat, Ignac Sivec, Hans Malicky and Table 1. List of sampling sites in Greece. European Ecoregions are taken from Illies (1978): Hellenic Western Balkan (6) and Eastern Balkan (7). 1 Thrace, E of Mega Derio N41°13'10" E26°03'03" 200 7 2
Data analysis. A list of species was compiled from all specimen data ( Table 2). Comparison of species richness and assemblage composition with published records from studied countries in the Balkans (Slovenia, Croatia, Bosnia & Herzegovina, Montenegro and Former Yugoslav Republic of Macedonia) was conducted by compiling species lists for those countries taken from Wagner ( , 1995, Horvat (1993Horvat ( , 1995aHorvat ( , 1995bHorvat ( , 1997 and Ivković et al. (2013aIvković et al. ( , 2013bIvković et al. ( , 2014. A species by country matrix was constructed and the Sørensen Index of Similarity of each pairwise comparison (Table 3) was calculated using the Primer v6 software (Clarke and Gorley 2006).   Table 1 for codes).
Description. Male. Body length approx. 3.5 mm (holotype dissected prior to measurement), wing length 3.7 mm (colouration bleached by prolonged storage in alcohol). Head in lateral view higher than long; gena narrow, nearly one-third height of eye. Frons short, broader than face. Face wide, with distinct carina on lower margin, bare, lacking setae. One pair of ocellar and one pair of vertical setae; about 5 distinct upper postoculars, subequal in size; lower postocular setae finer and merging Table 2. List of Greek aquatic dance flies and summary of their distribution. European Ecoregions are taken from Illies (1978): Hellenic Western Balkan (6) and Eastern Balkan (7).
Legs brownish; fore femur with two stronger anterior setae on apical fourth; uniformly covered with rows of small dark setulae. All coxae with longer setae anteriorly; fore coxae with several erect setae. Fore and mid femora ventrally with some longer setulae on proximal half, some longer than width of segment.
Abdomen covered in small setae. Terminalia (Figs 6, 7): hypandrium subequal in length with epandrium; narrow, with 8 pairs of short setae. Epandrium subrectangular, covered with long setae especially ventrally and laterally; surstylus thumb-like on inner face apically. Clasping cercus unilobed, pointed apically; finger-like, with small basal projection on inner face with setae; fine on outer face near anterior margin and apex; inner face with stouter setae, especially near posterior margin. Phallus more or less linear, slender; distiphallus similar to phallus shaft, narrow, without swellings.
Female. Unknown. Etymology. The species is named after the Greek mythology character Iphigenia, the priestess of the Greek Goddess Artemis.

Wiedemannia ljerkae
Diagnosis. This species of Wiedemannia is distinguished by the cercus with two long finger-like processes and a rounded pterostigma on the wings.
Description. Male. Body length 3.5-4.5 mm, wing length 4.0-4.3 mm (colouration bleached by prolonged storage in alcohol). Head (Fig. 2) in lateral view higher than long; gena broad, more than half height of eye. Frons short, broader than face. Face wide, with distinct carina on lower margin, bare, lacking setae. Ocellar setae short and fine; one pair of vertical setae; about 7-8 distinct upper postocular setae; lower postocular setae finer and merging with longer setae on middle and lower occiput; numerous dark setulae on vertex and between ocellar area and eye margin. Antenna brown; postpedicel and stylus minutely pubescent; pedicel slightly shorter than half length of scape, with complete circlet of subapical setae; postpedicel apically pointed, stylus nearly twice length of postpedicel; scape with setulae dorsally.
Legs mostly brown; fore femur with one stronger preapical anterior seta; uniformly covered with rows of small dark setulae. All coxae with longer setae anteriorly. Fore and mid femora ventrally with some longer setulae on proximal half.
Abdomen concolourous with thorax, covered in short setae. Terminalia (Figs 4, 8): hypandrium shorter than epandrium, bearing 4 pairs of setae. Epandrium subquadrate, covered with long dark setae especially ventrally and laterally; surstylus slender, digitiform. Clasping cercus with two long, slender, finger-like processes and small basal lobe with crown of spine-like setae on inner face apically; finger-like lobes with long setae distally; posterior finger-like lobe with inner cluster of stout setae at mid-length. Phallus more or less linear, very slender; distiphallus with distinct swelling at mid-length.
Etymology. The species is named after the first author's mother, Katica Ljerka Ivković, for all those things that mothers do for all of us.
Remarks. Wiedemannia ljerkae sp. n. is known only from several localities in Greece. On the basis of the multiple slender lobes of the clasping cercus and distinct pterostigma, W. ljerkae sp. n. appears closely related to W. braueri (Mik, 1880) and W. tricuspidata (Bezzi, 1905) (see Engel 1918Engel , 1940. Diagnosis. This species of Wiedemannia is distinguished by the faint clouding about crossveins and base of radial fork, shape of the clasping cercus and position of distiphallus on the phallic shaft. Description. Male. Body length 3.8-4.5 mm, wing length 5.2-5.3 mm (colouration slightly bleached by prolonged storage in alcohol). Head dark with brown frons and vertex, remainder of head with blue pruinescence; head higher than long; gena narrow, one-quarter height of eye. Frons short, broader than face. Face wide, with distinct carina on lower margin, bare, lacking setae. One pair of long ocellar setae and one pair of vertical setae; 6-7 distinct upper postoculars; lower postocular setae finer and merging with longer setae on middle and lower occiput; a few small setulae present on vertex and in ocellar area. Antenna brown; postpedicel and stylus minutely pubescent; scape longer than pedicel, with setulae dorsally; pedicel with complete circlet of apical setae; postpedicel apically pointed; stylus twice length of postpedicel.
Wing membrane infuscate with darkening at apex of cell dm, radial fork and r-m crossvein; veins darker; 1 short basal costal seta ending before humeral crossvein. Cell dm produced anteroapically. M 1 and M 2 originating separately from cell dm. CuA+CuP in form of short streak. Pterostigma broad and elongate, very distinct. Squama with setulae. Halter yellowish brown.
Legs mostly brown; fore femur with 2-3 strong anterior setae on apical quarter; uniformly covered with rows of small dark setulae. All coxae with longer setae anteriorly; fore coxa with 1-2 erect setae. Fore and mid femora ventrally with some longer setulae on proximal half.
Female. Similar to male. Terminalia: cercus short ovate and minutely pilose. Etymology. The species name is derived from the Latin nebulosus (misty, cloudy, dark), in reference to the clouding about the crossveins.
Remarks. Wiedemannia nebulosa sp. n. is known only from the type locality in Greece. On the basis of the shape of the clasping cercus, this new species is similar to W. carpathica Vaillant, 1967 (eastern Carpathians), W. pyrenaica Vaillant, 1967 (Pyrenees) and perhaps W. wachtli (Mik, 1880). Diagnosis. This species of Wiedemannia is distinguished by the long gena and the mitten-shaped clasping cercus, which is extremely similar to that of Wiedemannia (Chamaedipsia) berthelemyi Vaillant & Vinçon, 1987. Description. Male. Body length 3.5-4.1 mm, wing length 3.5-3.6 mm (colouration bleached by prolonged storage in alcohol). Head (Fig. 3) in lateral view higher than long; gena broad, three-quarters height of eye. Frons short, broader than face. Face wide, with distinct carina on lower margin, bare, lacking setae. One pair of short ocellar setae and one pair of vertical setae; about 6 distinct upper postocular setae; lower postocular setae finer and merging with longer setae on middle and lower occiput; few small setulae present on vertex and between ocellar area. Antenna brown; postpedicel and stylus minutely pubescent; scape longer than pedicel, with setulae dorsally; pedicel with complete circlet of apical setae; postpedicel apically pointed; stylus nearly twice length of postpedicel.
Legs mostly brown; fore femur with 1 strong preapical anterior seta; uniformly covered with rows of small dark setulae. All coxae with longer setae anteriorly. Fore and mid femora ventrally with some longer setulae on proximal half.
Female. Similar to male. Terminalia: cercus short ovate and minutely pilose. Etymology. The species name is derived from the name Wiedemannia (Chamaedipsia) berthelemyi because of the similarity of the clasping cercus with that of this species.
Remarks. Wiedemannia pseudoberthelemyi sp. n. is known only from parts of Greece. This new species differs from W. berthelemyi on the basis of the truncate pos-terior lobe of the clasping cercus (pointed in W. berthelemyi) and in having only a single preapical seta on the fore femur (2 in W. berthelemyi). The odd stout setae with multi-branched tips on the inner face of the clasping cercus were not noted by Vaillant and Vinçon (1987) and the absence of the swelling on the distiphallus (Vaillant and Vinçon 1987, fig. 32) is likely an artefact caused by the acid clearing process. The holotype of W. berthelemyi was not examined.
Additional similar species that could be included in this group based on the shape of the clasping cercus include: W. angelieri Vaillant, 1967 (Pyrenees), W. vedranae Ivković & Sinclair, 2014 (Sierra Nevada, Spain), and W. queyrasiana Vaillant, 1956 (European Alps). Diagnosis. A yellow-brown species with distinct, brown and rounded pterostigma, characterized in the male by dark brown cercus with elongate, slender forked process at mid-length, posteriorly tapered epandrium with stout inner setae and membranous distiphallus with two elongate lobes.

Chelifera horvati
Description. Male. Body length 4 mm, wing length 3.6 mm. Head dorsoventrally flattened, dark brown; ocellar triangle dark brown; all setae whitish. Eyes iridescent black; narrowly separated on face. Face with thick, whitish pubescence. One pair of postocular setae and scattered fine setae on vertex. Occiput bearing scattered fine setulae; gena with rather dense short, downwardly directed whitish pile. Antenna whitish, with scape and pedicel bearing distinct short dorsal setulae; postpedicel about 1.5× as long as wide, stylus much shorter than postpedicel.
Thorax elongate; yellow, all setae yellowish. Mesonotum with pair of brown vittae, extending around prescutellar depression; small dark spot posterior to postpronotal lobe and larger dark spot near wing base. Holotype missing most thoracic setae.
Legs whitish yellow, apical two tarsal segments on all legs brown. Fore coxa about 8× longer than wide with several pale dorsoapical setae. Fore femur slightly longer than fore coxa, more than 4× longer than wide, evenly inflated, widest at middle. Fore femur with two rows of black ventral denticles and two rows of strong outer brownish-yellow ventral setae, with following chaetotaxy: 20 anteroventral denticles, 6 anteroventral spine-like setae, 21 posteroventral denticles, 6 posteroventral spine-like setae; denticles closely spaced and rows converging distally; posteroventral spine-like setae shorter distally. Fore tibia 0.6× as long as fore femur, evenly curved with anteroventral row of short, spine-like setae; with apicoventral dark spur-like seta, longer than width of tibia. Mid and hind femora with anteroventral row of short, slender setae.
Female. Unknown. Etymology. The new species is named after the late Dr Bogdan Horvat, mentor of the first author, colleague and during his life a leading expert on the genus Chelifera Macquart.

List of Empididae of Greece (Clinocerinae & Hemerodromiinae)
The following format is used for the distributional data: Literature references -name of the site and in brackets the reference citation and site ID; New records -name of the site and in brackets the site ID. All the sites and their numbers are listed in Table 1.
Remarks. This species is newly recorded from Greece. The male terminalia of this species are illustrated (Fig. 12) to highlight additional detail not shown in the original drawing of Vaillant (1957, fig. IIC).

Wiedemannia (Wiedemannia) dyonysica
Greece supports at least 47 species, but this is unlikely to be the final number. Slovenia, situated in the northwest part of the Balkans, supports 58 species, Croatia 51 species, while Bosnia & Herzegovina, Montenegro and FYR Macedonia have 38, 34 and 34, respectively (Fig. 14). The Sørensen Index of Similarity showed that the Empididae fauna of Greece is most similar to that of FYR Macedonia followed by Bosnia & Herzegovina, whereas it is the least similar to that of Montenegro (Table 3).
We compared our list of Greek species with existing checklists in "Fauna Europaea" (Chvála 2012) and the World Catalogue of Empididae (Yang et al. 2007). The following species were not recorded from Greece in both these works: Chelifera angusta and Hemerodromia melangyna from the subfamily Hemerodromiinae, and Clinocera megalatlantica, Kowarzia plectrum, Phaeobalia dimidiata, W. (Chamaedipsia) beckeri, W. (Philolutra) angelieri and W. (P.) chvali from the subfamily Clinocerinae. They represent new country records. On the other hand, some species that are listed in Chvála (2012) and Yang et al. (2007) are not included in the present checklist. We omitted Wiedemannia (Philolutra) hygrobia (Loew) because its presence has not been confirmed in Greece. However, it is possible that it does occur in Greece as it is present in surrounding countries (Chvála 2012, Horvat 1995b and consequently it was included in the above key to species. Altogether, 13 species (including the new species) are recorded for the first time from Greece. The species richness of both subfamilies varies between European Ecoregions.
Comparison with neighbouring faunas. Greece has been divided into two ecoregions: Hellenic Western Balkan (Ecoregion 6) and Eastern Balkan (Ecoregion 7). The higher species richness is in the Hellenic Western Balkan Ecoregion, but the Eastern Balkan Ecoregion in Greece is much smaller, so this was an expected result. Greece supports at least 47 species, of which 10 are currently endemic to the country (Dolichocephala cretica, D. vaillanti, Clinocerella siveci, Roederiodes malickyi, Wiedemannia (W.) graeca, W. iphigeniae, W. ljerkae, W. nebulosa, W. pseudoberthelemyi, Chelifera horvati). The higher number of species recorded for Slovenia and the far fewer species recorded, for instance, in Montenegro, FYR Macedonia and Bosnia & Herzegovina should be viewed with caution. Slovenia was well studied (Horvat 1995a) in comparison to other  Balkan countries, which were only studied sporadically (Horvat 1993, 1995b, 2013b, 2014. Our comparison of Sørensen Similarity indices shows that the FYR Macedonia assemblage has the greatest similarity with the Greek assemblage. This was expected since FYR Macedonia borders with Greece, so they have many species in common. The lowest similarity is with Montenegro, which was not expected as it is geographically much closer to Greece, but this could be due to undersampling of that country (Ivković et al. 2014).

Concluding remarks
The Greek aquatic Empididae fauna is composed of exclusively Palearctic taxa with the exception of C. stagnalis, which is the most widespread clinocerine (known from North America, Asia, and North Africa) (Sinclair 2008). Most of the species are restricted to Europe or South Europe and some of them are only found in the Balkans and Greek islands (e.g., Dolichocephala zwicki, Wiedemannia (Chamaedipsia) ariadne, W. (Pseudowiedemannia) microstigma, W. (Wiedemannia) dinarica and W. artemisa). Some species have a small area of distribution, occurring in just one or a few sites (e.g., Chelifera horvati, Clinocerella siveci, Dolichocephala cretica, D. vaillanti, Roederiodes malickyi, Wiedemannia (W.) graeca, W. iphigeniae, W. ljerkae, W. nebulosa and W. pseudoberthelemyi), and can be considered as Greek endemics.
There are still some genera of Clinocerinae and Hemerodromiinae that have not been recorded in Greece and that might be present, as they occur in surrounding countries (e.g., Bergenstammia Mik, Chelipoda Macqaurt and Phyllodromia Zetterstedt). Within Greece, most species were reported from the Hellenic Western Balkan Ecoregion; this was expected as this European Ecoregion covers most of the surface area of the country (Illies 1978) and it is considered a biodiversity hotspot (Kryštufek and Reed 2004). The checklist presented here only includes species for which good evidence exists of their presence in Greece. As explained previously, we have omitted any ambiguous or doubtful data and references. This paper may serve as a baseline for planning future work in Greece, but also in surrounding countries for which knowledge of the aquatic dance fly fauna is poor, such as Albania, Bulgaria and Turkey.