Thrypticus —host plants, habitats and localities

The larvae of Thrypticus species are plant-miners and form mines within the stems of wetland or aquatic monocotyledons (Dyte 1959; Bickel & Hernandez 2004; Negrobov & Naglis 2020; Drake et al. 2023). For this purpose, females possess a strongly scletorized, blade-like oviscapt (Figs 11, 14) for piercing and ovipositing into plant tissue, a biological behaviour which is unique in the family (e.g., Johannsen & Crosby 1913; Parent 1924; Negrobov & Naglis 2020). The known host plants for the world fauna belong to the following families and genera: Cyperaceae (Schoenoplectus, Eleocharis), Poaceae (Muhlenbergia, Phragmites, Spartina), Juncaceae (Juncus), and Pontederiaceae (Eichhornia, Pontederia) (Dyte 1993; Hernández 2008; Schoenoplectus species listed as Scirpus).

The bulk of the faunistic data presented below originates from a survey conducted by the first author during 2021–2023 in 16 wetland localities, mainly in western Bohemia (westernmost part of the Czech Republic). In most cases, the sites were located on the banks of ponds/pools (or bed, if drained). The two sites that received extra attention are described below. Despite the lack of reliable data (no reared specimens), major or at least important genera of host plants for Palaearctic Thrypticus appear to be Schoenoplectus and Eleocharis. They are both listed by Dyte (1993) for the species of the northern, temperate part of the Nearctic Region (Maryland, Michigan) and mentioned (both mostly as Scirpus) in a number of the Palaearctic records, e.g. Storå (1956), Frey (1957), and Drake et al. (2023). Accordingly, the herein presented short term survey brought about the best results (both in terms of the number of species and specimens) precisely in those places where plants of both genera grew in abundance. For more details, see the Ecology section of the respective species records. An exception to this rule seems to be T. smaragdinus Gerstäcker, 1864 which has mainly been reported from Phragmites vegetations (see further).

Bolevecké rybníky (Bohemia, 49°47′N 13°23′E, altitude 310–340 m, Figs 1, 2)—a system of nine ponds in the northern suburban part of Plzeň, with a history dating back to the 15th century. These are mostly smaller ponds, with exception of the Velký bolevecký pond, which has an area of approximately 53 ha. Thrypticus flies were collected during a dedicated inventory (see above) on the banks of four ponds (Velký bolevecký, Kamenný, Senecký and Nováček pond), with Eleocharis spp. (mostly E. palustris (Linnaeus)) and/or Schoenoplectus lacustris (Linnaeus). Most records (five species and the majority of specimens) originate from the Velký bolevecký pond, which has the following characteristics (largely shared by other ponds, Figs 1, 2): oligotrophic lake-like pond with limited fish stock, and well-developed macrophyte cover, having shallow littoral and largely sandy banks (Jůza et al. 2019).

The species collected: Thrypticus bellus, T. bolevensis sp. nov., T. cuneatus (Becker, 1917), T. divisus (Strobl, 1880), T. laetus Verrall, 1912, T. nigricauda Wood, 1913 and T. pollinosus Verrall, 1912.

Soos (Bohemia, National Nature Reserve, 50°08′53″N 12°24′24″E, altitude 440 m, Figs 3, 4)—protected wetland area with the remains of former volcanic activity, located approximately 6 km northeast of Františkovy Lázně. A spectacular peatbog site with fens on numerous mineral spring effluents, emanations of pure carbon dioxide in mofettes, saltwater wetlands, and a diatomite shield in its central part (Horáčková 2012). The major saline habitats are halophytic common reed stands and salt marsh grasslands, with rare plant species, e.g. Glaux maritima Linnaeus and Scorzonera parviflora Jacquin (Brabec & Velebil 2019). Of the two major genera of host plants, there are extensive, largely monodominant stands of Schoenoplectus tabernaemontani whereas Eleocharis is also locally abundant, with at least two species, E. palustris and E. uniglumis (Link), see Brabec & Velebil (2018).

The species collected: Thrypticus bellus Loew, 1869, T. intercedens Negrobov, 1967, T. nigricauda Wood, 1913, T. tarsalis Parent, 1932 and T. virescens Negrobov, 1967.