Morphological,molecular and biological evidence reveal two cryptic species in Mecinus janthinus Germar (Coleoptera,Curculionidae), a successful biological control agent of Dalmatian toadflax,Linaria dalmatica (Lamiales,Plantaginaceae)

A combined morphological, molecular and biological study shows that the weevil species presently named Mecinus janthinus is actually composed of two different cryptic species: M. janthinus Germar, 1821 and M. janthiniformis To?evski & Caldara sp.n. These species are morphologically distinguishable from each other by a few very subtle morphological characters. On the contrary, they are more readily distinguishable by both molecular and biological characters. A molecular assessment based on the mitochondrial DNA cytochrome oxidase subunit II gene revealed fixed differences between the two species with p‐distances between samples of both species ranging from 1.3 to 2.4%. In addition to this, the larvae of the two species are found to develop on different species within the genus Linaria (Plantaginaceae): M. janthinus is associated with yellow toadflax (L. vulgaris) and M. janthiniformis with broomleaf toadflax (L. genistifolia) and Dalmatian toadflax (L. dalmatica). Molecular and host use records further suggest the occurrence of a third species associated with L. vulgaris within M. janthinus, sampled from north Switzerland, central Hungary and east Serbia. The significance of these new findings is of particular importance because species of the M. janthinus group are used, or are potential candidates, for the biological control of invasive toadflaxes in North America.     

Host‐associated genetic divergence and taxonomy in the Rhinusa pilosa Gyllenhal species complex: an integrative approach

A combined taxonomic, morphological, molecular and biological study revealed that stem‐galling weevils from the genus Rhinusa associated with toadflaxes from the genus Linaria (Plantaginaceae) are composed of three different species: Rhinusa pilosa, Rhinusa brondelii and Rhinusa rara sp.n. The authentic field host plants are respectively, Linaria vulgaris, Linaria purpurea and Linaria genistifolia/ Linaria dalmatica. These weevil species can be distinguished from each other by a few subtle morphological characteristics, mainly in the shape of the rostrum and of the integument. An analysis of the mitochondrial [cytochrome oxidase subunit II gene (COII) and 16S ribosomal RNA gene (16S)] and nuclear (elongation factor‐1α, EF‐1α) sequence data revealed high genetic divergence among these species. Uncorrected pairwise distances on mtCOII gene were 14.3% between R. pilosa and R. brondelii, 15.7% between R. pilosa and R. rara, while R. brondelii and R. rara were approximately 11% divergent from each other. Divergences obtained on 16S and nuclear EF‐1α genes were congruent. However, substantial intraspecific mitochondrial divergence was recorded for all studied populations of R. pilosa s.s. showing two mtDNA lineages, with estimated COII and 16S divergences of 4% and 1.6%, respectively. Nuclear pseudogenes (Numts) and Wolbachia influence, although recorded within both lineages, were excluded as possible causatives of the mtDNA divergence, while EF‐1α indicated absence of lineage sorting. Species from the R. pilosa complex are estimated to have diverged from each other approximately 7.2 million years ago (mya; late Miocene), while R. brondelii and R. rara diverged from each other about 4.7 mya (early Pliocene). This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:EEDD6248‐01DB‐4B4A‐B79D‐C5606393E3AA .