Morphological and chemical analysis of male scent organs in the butterfly genus Pyrgus (Lepidoptera: Hesperiidae)

The genome sequence of the grizzled skipper, Pyrgus malvae (Linnaeus, 1758)

We present a genome assembly from an individual male Pyrgus malvae (the grizzled skipper; Arthropoda; Insecta; Lepidoptera; Hesperiidae). The genome sequence is 725 megabases in span. The majority (99.97%) of the assembly is scaffolded into 31 chromosomal pseudomolecules, with the Z sex chromosome assembled.

Ultrastructure of androconia and surrounding scales of nine species of Hesperiidae (Lepidoptera)

The ultrastructure of androconia and their surrounding scales of nine species in nine genera across four subfamilies of Hesperiidae is studied. This provides a basis for the classification and identification of some genera and species. The wing surface of the scent glands patches was cut with scissors, observed and photographed under an S-4800 scanning electron microscope (at 10.0 kV accelerated pressure). There were significant differences in the types of scent glands patches across subfamilies. The scent glands patches of Pyrginae and Dudaminae are mainly in the costal fold of the forewing, while those of Coeliadinae and Hesperiinae are mainly in the line or circular stigma on the wing surface. The length, breadth and aperture of the androconia were further measured and the data are analysed by variance and multiple comparisons. There are significant differences amongst the subfamilies, except for Dudaminae and Pyrginae. In Hesperiinae, Telicotacolon (Fabricius, 1775) and Ampittiavirgata (Leech, 1890) have no significant difference in the aperture of the androconia, but are significantly different from Thymelicusleoninus (Butler, 1878). There are significant differences in the aperture between Pyrgusalveus’s (Hübner, 1803) androconium and the second androconium of Loboclabifasciata (Bremer & Grey, 1853), but not with the first androconium of Loboclabifasciata. The morphology of androconia in the scent glands patches is very similar in Hesperiinae; all are rod-shaped and paddle-like. The scale types around the scent glands patches are different, but there are one or two similar types. To a certain extent, the aperture of the androconia reflects the genetic relationships between subfamilies and species. The differences in scale type and structure of scent glands patches can be used as a reference for the classification of subfamilies and genera in Hesperiidae.

Doublesex Mediates the Development of Sex-Specific Pheromone Organs in Bicyclus Butterflies via Multiple Mechanisms

The Bicyclus lineage of satyrid butterflies exhibits male-specific traits, the scent organs, used for chemical communication during courtship. These organs consist of tightly packed brush-like scales (hair-pencils) that rub against scent patches to disperse pheromones, but the evolution and molecular basis of these organ’s male-limited development remains unknown. Here, we examine the evolution of the number and location of the scent patches and hair-pencils within 53 species of Bicyclus butterflies, and the involvement of the sex determinant gene doublesex (dsx) in scent organ development in Bicyclus anynana using CRISPR/Cas9. We show that scent patches and hair-pencils arose via multiple, independent gains, in a correlated manner. Further, an initially nonsex-specific Dsx protein expression pattern in developing wing discs becomes male-specific and spatially refined to areas that develop the scent patches. Functional perturbations of dsx show that this gene activates patch development in males whereas hair-pencils develop in both sexes without Dsx input. Dsx in females is, instead, required to repress hair-pencils whereas Dsx in males regulates minor aspects of its development. These findings suggest that the patches and hair-pencils evolve as correlated composite organs presumably due to their functional integration. Divergence in the function of dsx isoforms occurred across the sexes, where the male isoform promotes patch development in males and the female isoform represses hair-pencil development in females, both leading to the development of male-limited traits. Furthermore, evolution in number of patches in males is due to the evolution of spatial regulation of dsx.

The complete mitochondrial genomes of two skipper genera (Lepidoptera: Hesperiidae) and their associated phylogenetic analysis

The systematic positions of two hesperiid genera, Apostictopterus and Barca (Lepidoptera: Hesperiidae), remain ambiguous. We sequenced and annotated the two mitogenomes of Apostictopterus fuliginosus and Barca bicolor and inferred the phylogenetic positions of the two genera within the Hesperiidae based on the available mitogenomes. The lengths of the two circular mitogenomes of A. fuliginosus and B. bicolor are 15,417 and 15,574 base pairs (bp), respectively. These two mitogenomes show similar AT skew, GC skew, codon usage and nucleotide bias of AT: the GC skew of the two species is negative, and the AT skew of A. fuliginosus is negative, while the AT skew of B. bicolor is slightly positive. The largest intergenic spacer is located at the same position between trnQ and ND2 in A. fuliginosus (73 bp) and B. bicolor (72 bp). Thirteen protein-coding genes (PCGs) start with ATN codons except for COI, which starts with CGA. The control regions of both mitogenomes possess a long tandem repeat, which is 30 bp long in A. fuliginosus, and 18 bp in B. bicolor. Bayesian inference and maximum likelihood methods were employed to infer the phylogenetic relationships, which suggested that A. fuliginosus and B. bicolor belong in the subfamily Hesperiinae.

Ten genes and two topologies: an exploration of higher relationships in skipper butterflies (Hesperiidae)

Despite multiple attempts to infer the higher-level phylogenetic relationships of skipper butterflies (Family Hesperiidae), uncertainties in the deep clade relationships persist. The most recent phylogenetic analysis included fewer than 30% of known genera and data from three gene markers. Here we reconstruct the higher-level relationships with a rich sampling of ten nuclear and mitochondrial markers (7,726 bp) from 270 genera and find two distinct but equally plausible topologies among subfamilies at the base of the tree. In one set of analyses, the nuclear markers suggest two contrasting topologies, one of which is supported by the mitochondrial dataset. However, another set of analyses suggests mito-nuclear conflict as the reason for topological incongruence. Neither topology is strongly supported, and we conclude that there is insufficient phylogenetic evidence in the molecular dataset to resolve these relationships. Nevertheless, taking morphological characters into consideration, we suggest that one of the topologies is more likely.