Biosteres Foerster, 1862

None of the species currently included in the genus Biosteres attack fruit-infesting Tephritidae. However, most of the species now included in genera such as Fopius and Diachasmimorpha were formerly placed in Biosteres. See the Opiinae page for additional information on the current status of names of tephritid parasitoids formerly placed in Biosteres.

In the late 1800s, with works such as Marshall in Andre (1891), Biosteres was redefined largely on the basis of the short second submarginal cell, concealed clypeus, and incomplete occipital carina. Fischer (1972) revived this concept for his classification of Opiinae. Wharton (1988) noted that many of the species fitting this description did not appear to be closely related and included additional features that more narrowly restricted the definition of Biosteres. This resulted in the removal of species now placed in genera such as Fopius and Diachasmimorpha.

Taxonomic History / Nomenclature
Biosteres Foerster, 1862: 259. Type species: Bracon carbonarius Nees, 1834 (monobasic and original designation).

Type locality of type species: Germany; original type specimen lost, neotype male in Institut Royal des Sciences Naturelles de Belgique, Brussels, designated by Wharton (1987).

Used as a subgenus of Opius by Fischer starting about 1957 (e. g. Fischer 1957), with more formal redescription in Fischer (1959). Re-established as a genus in Fischer (1967). Accepted as genus by most subsequent authors, though with some disagreement about status (Tobias 1977, Tobias and Jakimavicius 1986).
Valid genus.

Diagnosis and Relationships
Biosteres has long been characterized on the basis of the small second submarginal cell of the fore wing (Figs 9, 11), concealed labrum (Figs 1, 4), and occipital carina that is present laterally and ventrally but widely absent dorsally. Additionally, the thick mandibles have a basal tooth or lobe ventrally (Figs 1, 2), both a dorsope (Fig. 8) and a large pronope are present, and the hind wing has distinct though weak m-cu and RS (Fig. 10). Tobias (1977) and Wharton (1988) discussed the overall resemblance of Biosteres with Opius s. s. while Li et al. (2013) emphasized differences how the basal tooth or lobe is formed in defining Opius s. s. relative to other opiines (without specifically comparing Opius to Biosteres). Essentially, the base of the mandible ventrally has a narrow, sharp tooth or carinate projection in Biosteres (Figs 1, 2), with the mandible more gradually narrowing distally. In the type species of Opius and its close relatives, the basal-ventral expansion is wider (Fig. 3), with a more abrupt demarcation between the broad basal and narrow, parallel-sided apical portions of the mandible.

Biosteres is a large genus with many valid species. Fischer (1972) divided Biosteres largely on the basis of sculptural characteristics, with Biosteres s.s. characterized by reduced sculpture, as represented by the loss of sculpture in the precoxal sulcus. Fischer (1972) used the name Chilotrichia for species that were more heavily sculptured, but Chilotrichia has also been treated as a separate genus on the basis of mandibular and clypeal characteristics. The type species of both Stenospilus Foerster, 1862 and Zetetes Foerster, 1862 also have sculptured precoxal sulci, and since Zetetes is a junior homonym, Stenospilus would be the oldest available name for those species with a sculptured precoxal sulcus. The scutellum is also heavily sculptured in some species of Biosteres, but sculpture on the scutellum is not always correlated with sculpture on the precoxal sulcus.

1. Biosteres face, clypeus, and ma...
2.Biosteres mandibles
3. opius dissitus clypeus and mandibles...
4.Biosteres face
5.Biosteres face
6. Biosteres mesoscutum...
7. Biosteres mesopleuron with ...
8. Biosteres T1 with dorsope...
No referenced distribution records have been added to the database for this OTU.
Biology / Hosts
Various biological information has been published on various species of Biosteres as parasitoids of flies in the family Anthomyiidae (especially vegetable pests in the genus Pegomyia such as the beetfly). Among the publications I have seen are those by Kemner (1925) (Swedish data), Bengtsson (1926) (mostly host lists), Bremer and Kaufmann (1928) (summary of known parasitoids, but most of focus on Utetes fulvicollis), Blunck et al., 1929 (as in Bremer and Kaufmann, with similar reports extending into the 1950’s: e. g. Kaufmann 1937), Cory (1916) (North American rearing records), Decoux and Roland (1934) (records from Belgium), Frost (1919) (North American record from dock), Gersdorf (1960), (1962), (1965) (data on parasitoids from Germany), Hawley (1925: 26) (parasitism on sugar-beet pests in Utah, USA), Kohlmeyer and Kohlmeyer (1960) (attacking Phorbia feeding in fungi), and Hille RisLambers (1932) (data from The Netherlands).