From Eastern Arc Mountains to extreme sexual dimorphism: systematics of the enigmatic assassin bug genus Xenocaucus (Hemiptera: Reduviidae: Tribelocephalinae)

A Revision of the Genus Argolis (Hemiptera: Reduviidae: Stenopodainae) from Asia

The assassin bug genus Argolis Stål, 1861 (Hemiptera: Reduviidae: Stenopodainae) has a disjunct distribution in Sub-Saharan Africa and Asia. In the present study, the Asian species of Argolis are revised. Two species are recognized, redescribed, and illustrated, with the following new subjective synonyms and new combination proposed: Argolis Stål, 1861 = Bardesanes Distant, 1909, syn. nov. = Neoklugia Distant, 1919, syn. nov.; A. farinator (Reuter, 1882) = N. typica Distant, 1919, syn. nov. = B. sericenotatus Livingstone & Ravichandran, 1989, syn. nov.; A. signata (Distant, 1909), comb. nov. (transferred from Bardesanes) = Caunus noctulus Hsiao, 1977, syn. nov. Lectotypes for C. farinator, B. signatus, and N. typica are designated. A key to separate the two Asian species of Argolis is provided. The sexual dimorphism, systematic relationships, and distribution of Argolis are discussed. Argolis is newly recorded from Laos, Pakistan, and Vietnam.

Phylogenetic comparative analysis supports aposematic colouration-body size association in millipede assassins (Hemiptera: Reduviidae: Ectrichodiinae)

The diversity of colour patterns and its importance in interactions with the environment make colouration in animals an intriguing research focus. Aposematic colouration is positively correlated with body size in certain groups of animals, suggesting that warning colours are more effective or that crypsis is harder to achieve in larger animals. Surprisingly, this relationship has not been recovered in studies investigating insects, which may have been confounded by a focus on aposematic taxa that are also gregarious. Millipede assassin bugs (Hemiptera: Reduviidae: Ectrichodiinae) comprise species with cryptic and aposematic colour patterns across a range of body sizes, are typically solitary as adults and are thus an excellent model for investigating a possible association between colouration and body size. Here, we use a comprehensive phylogeny for Ectrichodiinae, ancestral state reconstruction of colouration, and phylogenetic comparative methods to test for a colouration-body size association. The ancestor of Ectrichodiinae is reconstructed as cryptically coloured, with multiple subsequent transitions between aposematic and cryptic colouration. Aposematic colouration is positively associated with male body length and supports the hypothesis that selection on Ectrichodiinae body size may influence evolutionary transitions between aposematic and cryptic colouration or alternatively that selection for aposematic colouration influences body size evolution.