Systenus bartaki sp. n. is described from Croatia. The new species is similar to S. tener Loew and S. vasilii Grichanov but it differs by characters of the antennae and the male genitalia.

Dolichopodidae , Systenus , Croatia, new species

The genus Systenus Loew, 1857 is present in all biographical regions and includes worldwide 36 species (Yang et al. 2006, Bickel 2015). In the Palaearctic region 10 species are known and a revised key was provided by Negrobov (2005). The systematic position of the genus is still differently treated – Negrobov (1991, 2005) placed the genus in the Systeninae while Bickel (1986, 2015) proposed a placement in the Medeterinae. Species of the genus are known to be tree-trunk associated and the larvae develop in tree-hole debris (Vaillant 1978, Oboňa et al. 2012). Since members of the genus Systenus are usually rare in collections, examples of rich local sympatry are of special interest. For example six species were collected at the same locality near Manaus, Brazil (Naglis 2000), five species were collected from a single tree in Germany (Diestelhorst and Lunau 2001), three species were collected at the same collecting site in Switzerland (Naglis 2014), and eight species were collected at the same locality in Costa Rica (Bickel 2015).

The material was collected by means of a Malaise trap situated in the village of Gornji Muć, located 15 km from the Adriatic coast in the hinterland of the city of Split. The trap was placed on a sunny hill slope named Grudina at 500 m a.s.l., in an orchard, at position 43°41'27"N, 16°29'44"E on the southeast foothills of the Svilaja mountain. The cold and dry mountain air from the northeast is mitigated with moist and warmish southern winds creating the Submediterranean climate vegetation zone with dominant Quercus pubescens communities. To the south the collecting place was close to the fields and slopes planted with vineyards and orchards and to the north it was open to a small wood and pasture

Dipterans were sorted by means of morphospecies method and voucher specimens were dried and mounted on cards. The material examined is deposited in the collection of the Czech University of Life Sciences Prague (CULSP).

Body length is measured from the base of the antennae to the tip of abdominal segment 6; wing length from wing base to wing apex. The positions of features on elongate structures such as leg segments are given as a fraction of the total length, starting from the base. The following ratios are used: relative podomere ratios: femur, tibia, tarsomere 1/2/3/4/5; length of crossvein dm-cu to distal section of CuA (= CuAx ratio); distance between veins R₂₊₃ and R₄₊₅ to distance between R₄₊₅ and M at costal margin (= RMx ratio). Describing the hypopygium, dorsal and ventral refer to the position prior to rotation and flexion, i.e. in figures top is morphologically ventral and bottom is dorsal. If not otherwise indicated, the coloration of hairs and setae is black. Morphological terminology follows Cumming and Wood (2009).

Morphological abbreviations: ac = acrostichal setae; ad = anterodorsal; dc = dorsocentral setae; pd = posterodorsal; ppls = proepisternal setae.

Systenus bartaki is similar to S. tener Loew, 1859 and S. vasilii Grichanov, 2002. All species share the following characters: veins R₄₊₅ and M parallel in distal half; antennal scape and pedicel yellow. S. bartaki can be separated from the other two species by the short arista which is only 1/5 as long as the postpedicel, and by the postpedicel which is 3 times as long as high. In S. tener and S. vasilii the arista is at least 1/2 as long as the postpedicel and the postpedicel is 2-2.5 times as long as high. The male genitalia of S. bartaki are similar to that of S. vasilii, but differ by the broadened, triangular cercus which is longer than the surstylus, and by the curved hypandrium bearing a pair of long, sinuous setae. In S. vasilii the cercus is ribbon-shaped, shorter than the surstylus, and the hypandrium is not curved and bears short setae (see fig. 3 in Grichanov 2002).

I am thankful to Miroslav Barták (CULSP) for the loan of the material and for information about collecting site and methods and to Bože Kokan (Natural History Museum Split) for collecting the material. Dan Bickel (Sidney), Oleg Negrobov (Voronezh) and Andreas Sanchez (Neuchatel) provided useful comments on the manuscript.