Rivellia Robineau-Desvoidy, 1830

Bodner, L. & Freidberg, A., 2016, Taxonomy and immature stages of the Platystomatidae (Diptera: Tephritoidea) of Israel, Zootaxa 4171 (2), pp. 201-245 : 231-232

Rivellia Robineau-Desvoidy, 1830

Rivellia Robineau-Desvoidy, 1830: 729 . Type species: Rivellia herbarum Robineau-Desvoidy, 1830: 729 ( Musca syngenesiae Fabricius, 1781 ) (by subsequent designation of Rondani, 1869).

Selected references: Hennig, 1945: 6 (palaearctic Platystomatidae ); Soós, 1984: 40 (palaearctic catalog); Foote, 1985: 27 (biology of Rivellia pallida Loew ); Ferrar, 1987: 478 (breeding habits and immature stages); McMichael et al., 1990: 967 (biology of Rivellia melliginis (Fitch)) ; Korneyev, 2001: 5 (key to genera of palaearctic Platystomatidae ); McAlpine, 2001: 133 (Australasian genera of Platystomatidae ).

Diagnosis. Rivellia is related to Platystoma , being in the same subfamily ( Platystomatinae ). However, these two genera clearly differ from each other both in habitus and in detail, which makes their separation very easy. Platystoma are small-to-large species (3–10 mm long), usually almost entirely blackish or black, whereas Rivellia are mostly small (2.5–5.0 mm long) and often almost entirely yellowish. Platystoma are robust, with very broad abdomen, particularly basally, whereas Rivellia are delicate flies with narrow, spindle-shape abdomen that is narrowed towards base as well as towards apex. 1st flagellomere about 4 times as long as high in Rivellia , much shorter (1.3–2.7) in Platystoma . In Rivellia the wing pattern is clearly banded or reduced to small spots or none, whereas in Platystoma , the wing pattern is mostly reticulate, although in one species ( P. chrysotoxum Hendel ) it is banded, but differs from Rivellia species in the extensive wing pattern. In both genera cell dc is narrow at base, rather abruptly widened distally. However, the ratio of maximum length to maximum width of this cell is 2.5 in Rivellia , 3 in Platystoma . Platystoma has three pairs of scutellar setae, while Rivellia has only two. In Rivellia , the epandrium in lateral view is convex ventrally and with a posterior prolongation much longer than the anterior part, whereas in Platsytoma the epandrium is convex dorsally, and a prolongation, if present, is distinctly shorter than the anterior part. There are three spermathecae (2+1), less sclerotized than those of Platystoma , in which it specifically varies between three (2+1) and two spermathecae.

Distribution. Rivellia is a genus of approximately 150 described species, fairly evenly distributed in all zoogeographical regions except Antarctica. However, almost all Palaearctic species are known from Asia (particularly China and Korea), and only two species from Europe.

Comments. Based on Hennig’s key and descriptions of most Palaearctic species (1945), excluding the Korean species ( Byun et al., 1998), the Israeli species of Rivellia does not match any of these species, and is considered by us to be undescribed.