Phylogenetic relationships of aphid parasitoids from the genus Lipolexis Förster (Hymenoptera, Braconidae, Aphidiinae) with recognition of six new species

Abstract

The genus Lipolexis Förster is thought to be one of the least diverse genera of Aphidiinae. Both known species, L. gracilis and L. oregmae Gahan, are thought to have near-global distributions and to attack a very wide range of aphids in orchards, vegetable, forage and wheat crops. Two additional species were described from India (L. pseudoscutellaris Pramanik&Raychaudhuri and L. myzakkaiae Pramanik&Raychaudhuri) and one from China (L. wuyiensis Chen). However, they are sporadically mentioned in literature; some authors treat L. pseudoscutellaris as a synonym of L. oregmae, while some retain its species status. Lipolexis myzakkaiae and L. wuyiensis are currently recognized as valid species, but based on their morphological descriptions, all three species are conspecific with L. oregmae in our opinion. Despite their importance as biocontrol agents, taxonomic investigations on L. gracilis and L. oregemae are limited to a few old studies. Our preliminary examination of several Lipolexis populations revealed high variability in characters that are typically diagnostic of different species. As a result, we re-examined all available Lipolexis specimens, including those from BOLD (boldsystems.org), using both morphology and sequences from the barcode region of the COI gene. Patterns of sequence divergence at COI was congruent with morphological variability, indicating the presence of eight phylogenetic clades with distances ranging from 2.5% to 27.5%. The joint morphological and molecular results enabled recognition of five new species in the “gracilis“ group: Lipolexis sp.n.1 – Spain (Myzus persicae Sulzer), Slovenia (Aphis fabae Scopoli), China (Aphis gossypi Glover), Japan [Melanaphis sacchari (Zehntner), Toxoptera aurantii (Boyer De Fonscolombe)]; Lipolexis sp.n.2 – Pakistan (A. gossypi), India, Bangladesh; Lipolexis sp.n.3 - China, Japan (A. gossypi); Lipolexis sp.n.4 – Greece (A. fabae), Montenegro (Aphis punicae Passerini), Bosnia and Herzegovina (A. fabae, A. hederae Kaltenbach); Lipolexis sp.n.5 – Serbia (Myzus cerasi (F.), A. fabae), Croatia [Anoecia corni F., Myzus lythri (Schrank)], Spain (M. persicae), Slovenia (M. cerasi), Bulgaria, Moldova (M. cerasi), and one new species from the “oregmae” group: Lipolexis sp.n.6 - Bangladesh. The ecological and biocontrol roles of all Lipolexis taxa from various crops should be evaluated in the light of those findings.