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|Classification: Signiphoridae (Family) chalcids|
Chartocerus subaeneus (Förster, 1878) a chalcid|
Thysanus ater Haliday in Walker, 1840 a chalcid
Signiphoridae is a small cosmopolitan family with circa 6 valid genera and 76 species as of 1993. They are most abundant in the Neotropics. Important morphological characters include antenna with 1-4 annuli (ring segments), no funicle and a long unsegmented club. The scutellum is shaped like the metanotum (transverse and like a band). The mesonotal postphragma is very large, extending deeply into the gaster. They have a stout, flattened body and a long marginal fringe on the fore and hind wings.
This family is primarily hyperparasitic on scale insects, whiteflies and mealybugs through other Chalcidoidea. Several species are primary parasitoids of armored scales. Most are ectoparasitoids, although endoparasitoids are known. There has been no use made of this family in biological control, but their potential use is being considered.
NEARCTIC (CANADA).-- Yoshimoto (1984) noted that "This family contains small, more or less dorsoventrally flattened forms approximately 1 mm long. They can be separated from other families by the following characters: Body usually shiny, black, or partly yellow to orange. Ocelli widely spaced. Antenna with scape, pedicel, 1-4 anelli, and long cylindrical unsegmented club. Scutellum and metanotum reduced; scutellum transverse, narrowly ribbonlike. Gaster broadly sessile; propodeum large with large shining median triangular area. Wings often dark but bare, with long or short marginal setae; venation reduced, with postmarginal vein undeveloped."
"Only three genera, Signiphora Ashmead, Chartocerus Motschulsky, and Thysanus Walker, occur in Canada. These may be identified with the world keys of Rozanov (1965) and Subba Rao 91974), and with the North American keys by Girault (1913) and Quezada, DeBach and Rosen (1973)."
"All species are primary and often secondary parasites, mainly of scale insects (Coccoidea) and whiteflies (Aleyrodidae, Homoptera), but also pupal parasites of certain Diptera (for example, Chamaemyiidae and Tachinidae), and jumping plant lice (Psyllidae, Homoptera). Recent studies have shown that some species are primary parasites of diaspine scale insects (Diaspididae, Homoptera)."
PALEARCTIC (EUROPEAN former USSR).-- Trjapitcyn (1978/1987), as translated from the Russian, described this family as "Minute chalcids; length ranges from 0.5 to 2.0 mm. Body compact, streamlined or, sometimes, long and very flat. Antennae short, with four to seven segments; segments of funicle annular, and nonsegmented clava very long. Mandibles with two to three teeth. Disk of forewings almost glabrous; marginal fimbria usually long; marginal vein long, radial vein very short, postmarginal vein absent. Apical spur of middle tibiae long, serrated. Pygostyles located at tip of abdomen. Ectoparasites of chalcids and proctotrupoids, parasites of Coccoidea, Psylloidea, Aphidoidea and some Diptera; rarely primary parasites of puparia of flies of the families Chamaemyiidae and Chloropidae; species of the genus Signiphora are primary parasites of armored scales (Diaspididae) and Aleyrodoidea. Seven genera with more than 50 species known in world fauna; two genera with three species found in the European part of the USSR."
AFRICA.-- Prinsloo (1980) commented that this is a small family, comprised of only 5 genera. Of all chalcidoid families, the Signiphoridae (= Thysanidae) is least studied, and in Africa it is virtually unknown, even tho species are not uncommon. Prinsloo (1980) elaborated as follows:
Relationships & Diagnosis.-- "Superficially, the signiphorids resemble the Aphelinidae, but they differ clearly from the species of that family, and from those of all other families, in the shape of the antennae and the characteristic shape of the thorax, as described below."
Biology.-- "Little is known about the biology of this family. Most species are said to be external hyperparasitoids of scale insects and laeurodids (Coccoidea), psyllids, aphids and certain Diptera. Some species are also known to be primary ectoparasitoids in the puparia of the dipterous families Chamaemiidae and Chloropidae (Rozanov 1965) whereas others have been recorded as primary parasitoids of mealybugs. Species of the genera Chartocerus and Signiphora, which are the genera most commonly found in southern Africa, are frequently reared from scale insects of the family Diaspididae and Coccidae."
African Signiphoridae.-- "As mentioned above, the described fauna of this region is virtually non-existent, although unknown species of three of the five signiphorid genera are available for study. These are Chartocerus, Signiphora and Thysanus, genera that resemble each other closely; and until recently there was a tendency to group these, together with the other signiphorid genera, into a single genus, namely, Thysanus. Of the three genera mentioned, Thysanus is most readily separated by the occipital margin of the head which is rounded, not acutely angled, whereas Signiphora differs from Chartocerus in that the funicle in the female is three-segmented, not four-segmented as in the latter genus."
INDIA & ENVIRONS.-- Subba-Rao (1988) noted that "The family Signiphoridae contains six or seven genera and a few scores of species. It is an interesting group of chalcids characterized by the absence (sic) of a petiole, gaster broadly attached with the propodeum and the latter with a triangular impressed area in the middle, the scutellum is ribbon-like, and the wings are nearly devoid of discal setae. The known biologies show the members of this family as hyperparasites of primary chalcidoid parasites through their coccoid and other hosts. Although sometimes bred in large numbers, signiphorids are generally a rare group of chalcids."
"The signiphorid fauna of the Indian subcontinent is still very poorly and imperfectly known, being represented by three genera and nine species. Further studies may result in the discovery of other genera and several undescribed species."
History & Classification.-- "Since Walker described the genus Thysanus, the contributions to the taxonomy of this small family were made by several workers. Among these may be mentioned Howard (1894) who described the genus Signiphora and also placed it in a separate subfamily Signiphorinae. Later, Girault (1913), Mercet (1916), Silvestri (1918) and Nikol'skaya (1950) published on the group. The family as a whole was, however, reviewed by Rosanov (1965) who also gave a key to the genera. This was followed by the works of De Santis (1968), Hayat (1970) and Subba Rao (1974). As a result of these works the family presently contains six or seven genera: Thysanus Walker, Chartocerus Motschulsky, Signiphora Ashmead, Neosigniphora Rust (generally considered a synonym of Walker's genus, but shown to be valid by De Santis), Clytina Erdös, Kerrichiella Rosanov, and Rozanoviella Subba Rao."
"Ashmead (1900, 1904) treated the subfamily Signiphorinae in Encyrtidae. He, however, placed Thysanus in the tribe Aphelinini of the subfamily Aphelininae (= Aphelinidae of recent authors). Mercet (1916) and Silvestri (1918) brought together Thysanus and Signiphora under a single family-group. This group was first treated as an independent family Signiphoridae by Viereck (1916), and as Thysanidae by Peck (1951). Ferriere (1953) and more recently Gordh (In Krombein et al. 1979) placed signiphorids as a subfamily of Encyrtidae. In the present work this group is regarded as an independent family probably related to Encyrtidae."
"Most of the authors did not split this small family into subfamilies. De Santis (1968) proposed division of the family into two subfamilies: Signiphorinae Howard and Thysaniinae Peck, based on the number of funicle segments and the presence or absence of a seta on disc of the forewing or the hindwing. On the bases of three-dentate mandible and the comparatively longer and narrower wings with longer marginal fringe, Thysanus and Neosigniphora seem to be closely related and form a group separate from the other five genera in which the mandibles are two-dentate and the wings are relatively broader. But even this division seems unnecessary, as otherwise there is no appreciable gap to warrant division of the family into subfamilies without the risk of confusing generic characters with suprageneric ones."
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