Schistostoma Becker, 1902

Shamshev, Igor V. & Perkovsky, Evgeny E., 2022, A review of fossil taxa of Microphorinae (Diptera, Dolichopodidae sensu lato), with redescription of the Eocene genus Meghyperiella Meunier, Zootaxa 5150 (3), pp. 411-427 : 421

Schistostoma Becker

Schistostoma Becker, 1902: 46 . Type species: Schistostoma eremita Becker, 1902 , by monotypy.

Included fossil species. Schistostoma burmanicum Brooks, Cumming & Grimaldi, 2019: 122 (only male); S. foliatum Brooks, Cumming & Grimaldi, 2019: 124 (only male) (both species from northern Myanmar (Burmese amber), lowermost Cenomanian, Upper Cretaceous).

Remarks. Currently, Schistostoma is a broadly defined, problematic genus sometimes hardly distinguishable from Microphor ( Shamshev & Sinclair 2006; Brooks & Cumming 2022). Provisionally, monophyly of this lineage of microphorines could be supported by the medial hypandrial prolongation of male terminalia (absent in Microphor ) and by six or seven exposed female abdominal segments (five exposed segments in Microphor ) ( Brooks & Cumming 2022). It is evident that both these characters are not always easily-observable features, especially in fossils. In addition, the real number of exposed female abdominal segments may probably be difficult to distinguish sometimes due to pre-mortal behaviour and post-mortal changes of a specimen in semiliquid sticky resin (Martínez- Delclòs et al. 2004; Arillo 2007).

Schistostoma comprises 50 described extant and two extinct species. The recent species are distributed mostly in the Holarctic, although, three species are known from South Africa and only one species from the Oriental Region ( Shamshev & Sinclair 2006; Shamshev 2020; Brooks & Cumming 2022). Both extinct species of Schistostoma were described from Burmese amber and they have remarkably modified male forelegs, which is a unique feature within the genus and all fossil microphorines ( Brooks et al. 2019). In addition, there is a well-preserved male of an undescribed species of Schistostoma from Rovno amber (Shamshev & Perkovsky, unpubl. data). It is very similar habitually to the species from Burmese amber, but has simple legs.