Bombycoidea

Abstract: Butterflies and moths constitute some of the most popular and charismatic insects. Lepidoptera include approximately 160 000 described species, many of which are important model organisms. Previous studies on the evolution of Lepidoptera did not confidently place butterflies, and many relationships among superfamilies in the megadiverse clade Ditrysia remain largely uncertain. We generated a molecular dataset with 46 taxa, combining 33 new transcriptomes with 13 available genomes, transcriptomes and expressed sequence tags (ESTs). Using HaMStR with a Lepidoptera-specific core-orthologue set of single copy loci, we identified 2696 genes for inclusion into the phylogenomic analysis. Nucleotides and amino acids of the all-gene, all-taxon dataset yielded nearly identical, well-supported trees. Monophyly of butterflies (Papilionoidea) was strongly supported, and the group included skippers (Hesperiidae) and the enigmatic butterfly–moths (Hedylidae). Butterflies were placed sister to the remaining obtectomeran Lepidoptera, and the latter was grouped with greater than or equal to 87% bootstrap support. Establishing confident relationships among the four most diverse macroheteroceran superfamilies was previously challenging, but we recovered 100% bootstrap support for the following relationships: ((Geometroidea, Noctuoidea), (Bombycoidea, Lasiocampoidea)). We present the first robust, transcriptome-based tree of Lepidoptera that strongly contradicts historical placement of butterflies, and provide an evolutionary framework for genomic, developmental and ecological studies on this diverse insect order.

Abstract: The Ditrysia, which comprise the great majority of extant Lepidoptera, are divided into thirty superfamilies (instead of the fifteen to twenty usually recognized). Several of them are conceived in a new sense and one is newly proposed: the Choreutoidea. The Dudgeoneidae are reassigned to the Cossoidea, the Sematuridae and Uraniidae to the Geometroidea, while the Anthelidae and Lasiocampidae are placed in the Lasiocampoidea, a superfamily differing from the Bombycoidea mainly in retaining unfused prothoracic coxae in the larva. The Alucitoidea comprise the Tineodidae, Oxychirotidae and Alucitidae, and the Drepanoidea the Epicopeiidae and Drepanidae. Sister group relationships are recognized between the following superfamilies: Yponomeutoidea / Gelechioidea, Cossoidea / Sesioidea, Alucitoidea / Pterophoroidea, Hesperioidea / Papilionoidea and Drepanoidea / Geometroidea. Reliable monophyletic groups are the Mimallonoidea + Lasiocampoidea + Bombycoidea and the Hedyloidea + Rhopalocera. A few clades are suggested at a higher level, e.g. the Apoditrysia, the Obtectomera (based on two autapomorphies: pupa with fixed abdominal segments 1-4, and imago with modified pulvilli) and the Macrolepidoptera (mainly based on the shape of the first axillary sclerite in the forewing base). Several other changes are introduced: the ' Pseudocossinae' are restricted to the Madagascan genus Pseudocossus Kenrick (possibly belonging in the Brachodidae); the Macropiratinae (stat. n.) are regarded as the most primitive Pterophoridae; the Charideinae are transferred from the Zygaenidae to the Thyrididae; within the Thyrididae, the Argyrotypinae are regarded identical with the Siculodinae (syn. n.). Finally, two families are newly proposed within the Apoditrysia: the Simaethistidae (fam. n.) and Whalleyanidae (fam. n.). The superfamily relationships of these two families have not been determined.

Abstract: This study has as its primary aim the robust resolution of higher-level relationships within the lepidopteran superfamily Bombycoidea. Our study builds on an earlier analysis of five genes (∼6.6 kbp) sequenced for 50 taxa from Bombycoidea and its sister group Lasiocampidae, plus representatives of other macrolepidoteran superfamilies. The earlier study failed to yield strong support for the monophyly of and basal splits within Bombycoidea, among others. Therefore, in an effort to increase support specifically for higher-level nodes, we generated 11.7 kbp of additional data from 20 genes for 24 of 50 bombycoid and lasiocampid taxa. The data from the genes are all derived from protein-coding nuclear genes previously used to resolve other lepidopteran relationships. With these additional data, all but a few higher-level nodes are strongly supported. Given our decision to minimize project costs by augmenting genes for only 24 of the 50 taxa, we explored whether the resulting pattern of missing data in the combined-gene matrix introduced a nonphylogenetic bias, a possibility reported by others. This was achieved by comparing node support values (i.e. nonparametric bootstrap values) based on likelihood and parsimony analyses of three datasets that differ in their number of taxa and level of missing data: 50 taxa/5 genes (dataset A), 50 taxa/25 genes (dataset B) and 24 taxa/25 genes (dataset C). Whereas datasets B and C provided similar results for common nodes, both frequently yielded higher node support relative to dataset A, arguing that: (i) more data yield increased node support and (ii) partial gene augmentation does not introduce an obvious nonphylogenetic bias. A comparison of single-gene bootstrap analyses identified four nodes for which one or two of the 25 genes provided modest to strong support for a grouping not recovered by the combined-gene result. As a summary proposal, two of these four groupings (one each within Bombycoidea and Lasiocampidae) were deemed sufficiently problematic to regard them as unresolved trichotomies. Since the alternative groupings were always highly localized on the tree, we did not judge a combined-gene analysis to present a problem outside those regions. Based on our robustly resolved results, we have revised the classification of Bombycoidea: the family Bombycidae is restricted to its nominate subfamily, and its tribe Epiini is elevated to subfamily rank (Epiinae stat.rev.), whereas the bombycid subfamily Phiditiinae is reinstated as a separate family (Phiditiidae stat.rev.). The bombycid subfamilies Oberthueriinae Kuznetzov & Stekolnikov, 1985, syn.nov. and Prismostictinae Forbes, 1955, syn.nov., and the family Mirinidae Kozlov, 1985, syn.nov. are established as subjective junior synonyms of Endromidae Boisduval, 1828. The family Anthelidae (Lasiocampoidea) is reincluded in the superfamily Bombycoidea.

Abstract: The 15,389-bp long complete mitogenome of the endangered red-spotted apollo butterfly, Parnassius bremeri (Lepidoptera: Papilionidae) was determined in this study. The start codon for the COI gene in insects has been extensively discussed, and has long remained a matter of some controversy. Herein, we propose that the CGA (arginine) sequence functions as the start codon for the COI gene in lepidopteran insects, on the basis of complete mitogenome sequences of lepidopteran insects, including P. bremeri, as well as additional sequences of the COI start region from a diverse taxonomic range of lepidopteran species (a total of 53 species from 15 families). In our extensive search for a tRNA-like structure in the A+T-rich region, one tRNATrp-like sequence and one tRNALeu (UUR)-like sequence were detected in the P. bremeri A+T-rich region, and one or more tRNA-like structures were detected in the A+T-rich region of the majority of other sequenced lepidopteran insects, thereby indicating that such features occur frequently in the lepidopteran mitogenomes. Phylogenetic analysis using the concatenated 13 amino acid sequences and nucleotide sequences of PCGs of the four macrolepidopteran superfamilies together with the Tortricoidea and Pyraloidea resulted in the successful recovery of a monophyly of Papilionoidea and a monophyly of Bombycoidea. However, the Geometroidea were unexpectedly identified as a sister group of the Bombycoidea, rather than the Papilionoidea.