The genus Praon represents a large group of aphid endoparasitoids and is exemplary for the problems encountered in their taxonomy because of a great variability of morphological characters. To investigate the intraspecific variability and to ascertain cryptic speciation within the Praon abjectum Haliday group, biotypes in association with the aphid hosts Aphis sambuci L., Longicaudus trirhodus Walker, and Rhopabsiphum spp. were examined. We combined molecular and geometric morphometric analyses, that is, partial sequences of the mitochondrial cytochrome oxidase subunit I and nuclear 28SD2 genes and the shape of the forewing. Low variation of 28SD2 sequences confirmed the close relatedness of species from the genus Praon. Analysis of the cytochrome oxidase subunit I sequences however identified three separate taxa within the P. abjectum group with substantial genetic divergence. The biotype of P. abjectum associated with L. trirhodus differed from those associated with Rhopabsiphum sp. and A. sambuci by 5.4–6.5% and 7.7% sequence divergence, respectively, while the genetic distance between the latter two biotypes ranged from 9.5 to 10%. The main changes in the forewing shape that discriminate these three biotypes as revealed by geometric morphometrics are related to the stigma shape and the position of the radial nerve. Based on the differences determined in mitochondrial sequences and in the shape of the wing, we describe two new cryptic species within the P. abjectum group as follows: P. sambuci sp. n. in association with A. sambuci/S. nigra and P. longicaudus sp. n. in association with L. trirhodus/T. aquilegifolium.