Synosis Townes 1959

Face and clypeus forming a rather uniformly convex surface, without groove separating the clypeus from face; frons lacking an inter-antennal lamella and face lacking a transverse ridge before antennae; labrum not conspicuously exposed when mandibles are closed; mandible narrow with lower tooth shorter than upper tooth; fore wing with 3rs-m absent notauli distinct to about half the length of the mesoscutum, mesoscutum punctate; propodeum with distinctive pattern of anteriorly converging lateromedian longitudinal carinae, converting to a narrow carina or area of convergence as broad or broader than thickness of the carinae combined; anterior transverse carinae present (Figure 6A, D) or absent, sometimes replaced by grooves; posterior transverse carina complete and strong, except in Synosis ugaldei; lateromedian longitudinal carina absent or weak (in Synosis rubinus sp. nov.) (Figure 6A) behind posterior transverse carina; propodeal spiracle small and oval; metasoma punctate; first metasomal tergite with median carinae strong to at least posterior third of tergite; body rather evenly covered in setae; mid tibia with outer (anterior) spur slightly to conspicuously longer than the inner (posterior) one, hence the reverse of the situation for the hind tibia, which has the outer spur shorter (the opposite to most metopiine genera, except Forrestopius). Ovipositor short, not projecting beyond apex of metasoma.

The monophyly of Synosis is supported by the unique modified propodeal carinae, which enclose separate triangular areae superomedia and basalis (Gauld and Sithole 2002), a feature also mentioned by Townes (1971) and Townes and Townes (1959); Broad and Shaw (2005) noticed that in British species lateromedian longitudinal carinae of the propodeum converge anteriorly to a narrow carina or the area of convergence as broad or broader than the thickness of the carinae combined and the anterior transverse carinae are either present or absent, similar characteristics and variations were found in some of the Peruvian specimens. Another feature only found in Synosis is a band of setae along the upper margin of the metapleuron, elsewhere it is bare, the band is not well developed in Synosis parenthesellae Broad and Shaw (Broad, personal communication). The pattern of setosity on the metapleuron varies considerably in other metopiine genera but is never of the form found in Synosis.

In addition, according to Townes (1971) species of the genus have the epipleura of the first two metasomal tergites vestigial and that of the third and following terga wide. However, in some Peruvian specimens the epipleura of all tergites are well developed.