Phylogeny of Chrysotoxum species (Diptera: Syrphidae) inferred from morphological and molecular characters

Abstract

Abstract. Relationships of nine Italian Chrysotoxum species were analysed using morphological and molecular data. The morphology-derived cladogram revealed three well-defined groups: (i) C. cautum, (ii) the arcuatum group (C. arcuatum, C. fasciolatum) and (iii) the festivum group (C. festivum -C. vernale, C. bicinctum, C. elegans, C. octomaculatum and C. parmense). Trees inferred from COI-tRNALeu-COII sequences were largely in agreement, but they identified (i) C. parmense as an isolated branch, (ii) C. festivum and C. vernale as separate entities, (iii) C. elegans within a paraphyletic C. festivum clade. ITS2 trees were partially unresolved but C. parmense sequence emerged as a sister to the festivum group. The monophyly of the festivum group derived from morphological data was rejected by a phylogenetic test performed on combined molecular data set. The diagnostic value of some morphological characters commonly used to identify Chrysotoxum species is therefore questioned.

Taxonomy ofChrysotoxum festivum Linnaeus, 1758 (Diptera: Syrphidae) - an integrative approach

“…Melanostoma mellinum (Linnaeus, 1758) was used as outgroup, and Leucozona laternaria (Müller, 1776), Chrysotoxum cautum (Harris, 1776), and C. festivum sequences published by Masetti et al . () (GenBank accession numbers and ) were included. The final dataset from the parsimony analysis contained 42 sequences.…”

“…Chrysotoxum gracile , clearly separable by the longer scape than pedicel from C. elegans and C. festivum , is not included in the present study. Based on mtDNA and internal transcribed spacer 2 (ITS2), C. festivum and C. elegans appeared in the same clade (Masetti et al ., ).…”

“…In their results this genus appeared in the clade together with Epistrophe. Masetti et al (2006) analysed relationships among nine Italian Chrysotoxum species using morphological and molecular data. DNA sequence information from mitochondrial or nuclear genes did not correspond with morphological concepts and relationships within the genus remained unresolved.…”

“…The suggested reasons for identical haplotypes between taxa are retained polymorphism or mitochondrial introgression between the taxa (Ståhls et al, 2009). In their TAXONOMY OF CHRYSOTOXUM FESTIVUM 85 study, Masetti et al (2006) concluded that the COI/ COII region was more useful for phylogenetic reconstruction within the genus Chrysotoxum than for species identification. In their study, monophyly of the festivum group was rejected by a phylogenetic test performed on combined molecular data set (COI/COII and ITS2) and the taxonomic status of C. elegans and C. festivum as two separate species was identified as open to question.…”

Molecular analysis meets morphology‐based systematics—a synthetic approach for Chalarinae (Insecta: Diptera: Pipunculidae)

“…It has been shown here for molecular distances of cox1 that intraspecific pairwise genetic distance can exceed interspecific distance when comparing taxa from different species groups of the same genus and even between sister species of the same species group, a circumstance also known from other families of Diptera [see Bernasconi et al (2007) for Dolichopodidae, Smith et al (2006) for Tachinidae, Masetti et al (2006) for Syrphidae]. Thus, setting a fixed quantitative threshold to circumscribe species, as proposed, for example, by Hebert et al (2004), must be rejected.…”