Comparative morphology of male genital skeletomusculature in the Leptanillinae (Hymenoptera: Formicidae), with a standardized muscular terminology for the male genitalia of Hymenoptera

The male genitalia of the Insecta are famed for structural and functional diversity. Variation in this anatomical region shows ample phylogenetic signal, and this variation has proven indispensable for classification across the insects at multiple taxonomic ranks. However, in the ants (Hymenoptera: Formicidae) the male genital phenotype is ancillary to the morphology of the worker caste for systematic purposes. Ants of the enigmatic subfamily Leptanillinae are an exception, as males are easier to collect than workers. Ongoing systematic revision of the Leptanillinae must therefore rely upon the male phenotype – particularly the spectacular morphological profusion of the male genitalia. To thoroughly illuminate this anatomical region and aid comparative morphological research on ant male genitalia, we present a comparative morphological study of the male genitalia in nine exemplar lineages spanning the Leptanillinae, plus three outgroups representing other major clades of the Formicidae. We use micro-computed tomography (micro-CT) to generate 3D volumetric reconstructions of male genital skeletomusculature in these specimens. Our descriptions use new muscular terminology compatible with topographic main-group systems for the rest of the pterygote soma, and applicable to all Hymenoptera. We find that male genitalia in the Leptanillinae show an overall trend towards skeletomuscular simplification, with muscular reduction in some cases being unprecedented in ants, or even hymenopterans in general. In several lineages of the Leptanillinae we describe derivations of the male genitalia that are bizarre and unparalleled among the Hymenoptera. We conclude by discussing the functional implications of the often-extreme morphologies here observed

Supplementary material 1 from: Griebenow ZH, Jones SC, Eaton TD (2017) Seeking quantitative morphological characters for species identification in soldiers of Puerto Rican Heterotermes (Dictyoptera, Blattaria, Termitoidae, Rhinotermitidae). ZooKeys 725: 17-29. https://doi.org/10.3897/zookeys.725.20010

Subterranean termites in the genus Heterotermes Froggatt (Rhinotermitidae: Heterotermitinae) are pantropical wood feeders capable of causing significant structural damage. The aim of this study was to investigate soldier morphological attributes in three Puerto Rican species of Heterotermes previously identified by sequencing of two mitochondrial genes and attributed to Heterotermes tenuis (Hagen), H. convexinotatus (Snyder) and H. cardini (Snyder). Soldiers (n = 156) were imaged and measured using the Auto-Montage image-stacking program. We demonstrated that Puerto Rican Heterotermes soldiers could not be identified to species level based upon seven morphometric indices or any combination thereof. Nor could differences in soldier head pilosity be used to discriminate species, in contrast to previous findings. However, previously described characters of the soldier tergal setae were reported to be useful in discriminating H. tenuis from both of its Puerto Rican congeners

Seeking quantitative morphological characters for species identification in soldiers of Puerto Rican Heterotermes (Dictyoptera, Blattaria, Termitoidae, Rhinotermitidae)

Subterranean termites in the genus Heterotermes Froggatt (Rhinotermitidae: Heterotermitinae) are pantropical wood feeders capable of causing significant structural damage. The aim of this study was to investigate soldier morphological attributes in three Puerto Rican species of Heterotermes previously identified by sequencing of two mitochondrial genes and attributed to Heterotermes tenuis (Hagen), H. convexinotatus (Snyder) and H. cardini (Snyder). Soldiers (n = 156) were imaged and measured using the Auto-Montage image-stacking program. We demonstrated that Puerto Rican Heterotermes soldiers could not be identified to species level based upon seven morphometric indices or any combination thereof. Nor could differences in soldier head pilosity be used to discriminate species, in contrast to previous findings. However, previously described characters of the soldier tergal setae were reported to be useful in discriminating H. tenuis from both of its Puerto Rican congeners