Two new species of Thrypticus Gerstäcker from Turkey (Diptera, Dolichopodidae), with checklist and key to Palaearctic species.

Thrypticus caeruleus Naglis Negrobov sp. nov. and T. kechevi Naglis Negrobov sp. nov. are newly described from Turkey. Thrypticus viridis Parent is redescribed and the hypopygium is figured in detail. A revised checklist and key to males of Palaearctic species of the genus Thrypticus Gerstäcker including 26 valid species are provided. Thrypticus paludicola Negrobov is restored from synonymy with T. intercedens Negrobov based on hypopygial differences. Thrypticus tonsus Negrobov is regarded as new synonym of T. subtilis Negrobov.


Introduction
The genus Thrypticus Gerstäcker comprises 26 valid species in the Palaearctic Region including the herein newly described species. The latest comprehensive taxonomic work on the Palaearctic species of Thrypticus is the revision of the subfamily Medeterinae by Negrobov & Stackelberg (1971-77). Since then two new Palaearctic species of Thrypticus have been described: T. aphroditus Negrobov &Tsurikov, 1986, andT. mongoliensis Negrobov, Selivanova &Maslova, 2019. The larvae of Palaearctic Thrypticus species are plant-miners on Monocotyledons, especially on Phragmites australis (Cav.) and Juncus sp. (Dyte 1993). Some Neotropical species have been reared from rather soft petioles and stems of Pontederiaceae, especially on Eichhornia Kunth and Pontederia L., and were studied as potential biological control agents of water hyacinths (Bickel & Hernandez 2004). Females of Thrypticus possess a strongly scletorized, blade-like oviscapt for piercing and ovipositing into plant tissue, a biological behaviour which is unique in the family.
Two new species of Thrypticus are herein described and a checklist of Palaearctic Thrypticus is provided, including a new synonym and one reinstated species. In addition, a revised key to the Palaearctic species is provided.

Material and methods
The material of the new species was collected by M. Barták and S. Kubík and deposited in the collection of Czech University of Life Sciences Prague (CULSP). The type specimen of T. viridis Parent was borrowed from the Senckenberg Deutsches Entomologisches Institut, Müncheberg (SDEI).
The key to males is based primarily on Negrobov & Stackelberg (1971-77), but includes all subsequently and herein newly described species or species removed through synonymy. The checklist includes all known Palaearctic species. All taxonomic and nomenclatorial changes have been considered and errors have been corrected. For each species the original combination with year of publication and page number is provided. Synonyms are listed in chronological order. Distributional data is mainly according to Yang et al. (2006) and Grichanov (2020) if not otherwise indicated. Countries are listed in alphabetical order, and the distribution in zoogeographical regions outside the Palaearctic is also given.
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 R 2+3 and R 4+5 to distance between R 4+5 and M at costal margin (= RMx ratio). In describing the hypopygium, dorsal and ventral refer to the position prior to rotation and flexion; i.e., in figures the top is morphologically ventral and bottom is dorsal. Morphological terminology follows McAlpine (1981) except for the male hypopygium where terms of Cumming et al. (1995) and Sinclair (2000) are used.
Unlike many other dolichopodid genera, males of Thrypticus have few secondary sexual characters, and the examination of the male genitalia is usually necessary for reliable identification.
In Negrobov & Stackelberg (1971-77) some different terms of the male genitalia and wing veins are used. For a simplified comparison we give here both terminologies (Table 1).
Morphologic terminology used in the present work Morphologic terminology used in Negrobov & Stackelberg (1971-77)  Diagnosis. Antennae black, thorax and abdomen shiny blue-violet, with yellow setae; legs dark with yellow knees; mid tibia without ad seta; scutellum with only 2 strong marginal setae; cercus yellow; surstylus slender, yellow with black apex.
Etymology. The name of the new species refers to its blue shiny thorax and abdomen. Remarks. Using the key in Negrobov & Stackelberg (1971-77), the new species runs to T. nigricauda Wood, but can be distinguished by the characters given in the key below. The male genitalia resemble that of T. divisus ( Fig. 8B) but the new species is lacking an ad seta on the mid tibia and the apex of the surstylus is almost triangular and without notches.
Etymology. The new species is dedicated to the Bulgarian dipterist, Mihail Kechev. Remarks. Using the key in Negrobov & Stackelberg (1971-77), the new species runs to T. viridis Parent, but can be distinguished by the characters given in the key below. The new species shows some similarity in the hypopygial characters with T. pruinosus (Fig. 9C) (see Remarks under that species) having a cercus with a strong apical projection, but the shape and chaetotaxy of the surstylus is quite different. Diagnosis. Antennal scape yellow, pedicel partly yellow, postpedicel black, thorax and abdomen shiny metallic green, with yellow setae; legs entirely yellow; mid tibia with strong ad seta; scutellum with 2 strong marginal setae and 2 smaller lateral setae; surstylus and cercus yellow.

Key to males of Palaearctic species of Thrypticus
Thrypticus riparius Negrobov, 1971 was described based on a female, but has been tentatively included in the key based on the known female characters. Thrypticus pruinosus Parent is included in the key in the sense of Negrobov & Stackelberg (1971) but the species probably represents a different species. Antennal scape and pedicel yellow; hypopygium Fig. 6E Negrobov & Stackelberg (1971-77)).  Negrobov & Stackelberg (1971-77)).