Rivasia Askew & Nieves-Aldrey incertae sedis new placement, 2005

Burks, Roger, Mitroiu, Mircea-Dan, Fusu, Lucian, Heraty, John M., Jansta, Petr, Heydon, Steve, Papilloud, Natalie Dale-Skey, Peters, Ralph S., Tselikh, Ekaterina V., Woolley, James B., van Noort, Simon, Baur, Hannes, Cruaud, Astrid, Darling, Christopher, Haas, Michael, Hanson, Paul, Krogmann, Lars & Rasplus, Jean-Yves, 2022, From hell's heart I stab at thee! A determined approach towards a monophyletic Pteromalidae and reclassification of Chalcidoidea (Hymenoptera), Journal of Hymenoptera Research 94, pp. 13-88 : 13

Rivasia Askew & Nieves-Aldrey incertae sedis new placement

Rivasia Askew & Nieves-Aldrey, 2005. Type species: Rivasia fumariae Askew & Nieves-Aldrey, 2005

Diagnosis.

Antenna with 8 flagellomeres, including an undivided or incompletely divided clava. Eyes slightly ventrally divergent. Clypeus transverse. Labrum exposed, well-sclerotized. Mandibles with 2 teeth. Subforaminal bridge with postgena separated by lower tentorial bridge except for a small postgenal bridge dorsal to the hypostoma; posterior surface of head without postgenal lamina or postgenal groove. Pronotum subconical and elongate in dorsal view. Mesoscutellum with frenum; mesopleural area without an expanded acropleuron, without pits; mesepimeron extending over anterior margin of metapleuron; one mesofurcal pit present. Fore wing marginal vein subequal to stigmal vein in length; uncus elongate. All legs with 5 tarsomeres; protibial spur stout and curved. Metasoma with syntergum, therefore without epipygium.

Discussion.

Rivasia is usually the sister group of fellow incertae sedis taxon Asaphesinae in molecular analyses (Cruaud et al., submitted), although the two groups share few distinctive features morphologically. Instead, Rivasia more strongly resembles the subfamily Micradelinae , though never forming a clade with it. Rivasia shares no particularly distinctive features with Ormocerinae ( Pteromalidae ) nor any former part of it, differing from them in numerous features listed in the diagnosis.

Micradelinae can be distinguished from Rivasia by having a shorter, transverse pronotum and brownish coloration, in contrast with the longer pronotum and metallic coloration of Rivasia . Asaphesinae differ from Rivasia in a number of features, including the presence of 8 flagellomeres instead of 12, the lack of an occipital carina, and from extant species in the lack of pits on the mesopleural area.