Redescription and systematic affinities of Moltenia rieki Schlüter, 2000 (Xyelidae: Archexyelinae) (Molteno Formation, South Africa), one of the rare Gondwanan Triassic Hymenoptera

Using Reflectance Transformation Imaging, we re-examined the holotype of Moltenia rieki Schlüter, 2000, one of the few Triassic Hymenoptera known from Gondwana. The new data revealed characters of venation which were overlooked and/or misapprehended in the original description, and which have putative systematic relevance. Notably, the branching point of Rs, previously assumed to be located in a distal position, is actually located basal to the 2r-rs cross-vein, a trait suggesting a placement within the subfamily Archexyelinae. In combination with other traits, such as a very short 1-Rs and a fully sclerotized pterostigma, Moltenia rieki stands out as a distinctive member of this taxon. This study broadens our knowledge of early Hymenoptera evolution and suggests a wide Triassic distribution for Archexyelinae.