Dasycerine rove beetles: Cretaceous diversification, phylogeny and historical biogeography (Coleoptera: Staphylinidae: Dasycerinae)

Bayesian tip-dated phylogeny and biogeography of Cissampelideae (Menispermaceae): Mitigating the effects of homoplastic morphological characters

The integration of morphological and molecular data is essential to understand the affinities of fossil taxa and spatio-temporal evolutionary processes of organisms. However, homoplastic morphological characters can mislead the placement of fossil taxa and impact downstream analyses. Here, we provide an example of how to mitigate effectively the effect of morphological homoplasy on the placement of fossil taxa and biogeographic inferences of Cissampelideae. We assembled three data types, morphological data only, morphological data with a molecular scaffold and combined morphological and molecular data. By removing high-level homoplastic morphological data or reweighting the morphological characters, we conducted 15 parsimony, 12 undated Bayesian and four dated Bayesian analyses. Our results show that the 14 selected Cissampelideae fossil taxa are placed poorly when based only on morphological data, but the addition of molecular scaffold and combination of morphological and molecular data greatly improve the resolution of fossil nodes. We raise the monotypic Stephania subg. Botryodiscia to generic status and discover that three fossils previously assigned to Stephania should be members of Diploclisia. The Bayesian tip-dated tree recovered by removing homoplastic morphological characters with a Rescaled Consistency Index <0.25 has the highest stratigraphic fit and consequently generates more reasonable biogeographic reconstruction for Cissampelideae. Cissampelideae began to diversify in Asia in the latest Cretaceous and subsequently dispersed to South America around the Cretaceous-Palaeogene boundary. Two dispersal events from Asia to Africa occurred in the Early Eocene and the Late Eocene-Late Oligocene, respectively. These findings provide guidelines and practical methods for mitigating the effects of homoplastic morphological characters on fossil placements and Bayesian tip-dating, as well as insights into the past tropical floristic exchanges among different continents.

The thoracic anatomy of Pselaphus heisei (Pselaphinae, Staphylinidae, Coleoptera)

We document external and internal thoracic structures of the free-living pselaphine beetle Pselaphus heisei (Pselaphitae) using a set of traditional and modern techniques. Like in the specialized myrmecophile Claviger testaceus (Clavigeritae), the skeletal elements of the pro- and pterothorax are highly compact, with largely reduced inter- and intrasegmental sutures. Features previously listed as synapomorphies of staphylinid subgroups, to which Pselaphinae belong, are confirmed for P. heisei. The only previously proposed thoracic synapomorphy of Pselaphinae, the mesoventral foveae, is likely transformed in P. heisei: we assume that the concavities are directed mesad and internally fused, thus forming a broad channel ("perforation") extending through the keel-like median region of the mesoventrite. The prothoracic foveal system is strongly reduced, with only one pair of pits present in front of the procoxae. Their internal invaginations form a transverse ventral endoskeletal bar that stabilizes the prothorax. The condition observed in the free-living P. heisei is in contrast with previous hypotheses linking the reduction of the foveal system with myrmecophily. Moreover, traces of the mesoventral foveae are even preserved in the highly specialized inquiline C. testaceus. Gland cells are associated with areas of hyaline squamose setae on different body regions, suggesting release of secretions on the ventral side of the head, pro- and mesothorax, and abdominal base. Similar specialized setal patches are common in Pselaphini and related groups within Pselaphitae. The prothoracic musculature in P. heisei is more complex than that in the myrmecophilous C. testaceus and the free-living, unspecialized Creophilus maxillosus (Staphylininae). The metathoracic muscle system is strongly simplified, demonstrating that P. heisei cannot fly, even though wings, some skeletal elements of the flight apparatus, and some small direct flight muscles are preserved. It cannot be fully excluded that indirect flight muscles and thus a functional flight apparatus is preserved in a certain percentage of individuals.

Taxonomy and phylogeny of the Japanese species of the genus Dasycerus Brongniart (Coleoptera: Staphylinidae: Dasycerinae) with description of a new species and notes on D. poseidon Hu &amp; Liang

Dasycerus occultus Hashizume & Maruyama, sp. nov. is described and illustrated based on specimens from Japan (Honshu and Kyushu). The holotype of D. japonicus Nakane, 1963 was revisited. The “D. japonicus” illustrated by Löbl & Calame (1996) was found not to be D. japonicus but rather to be D. occultus sp. nov. The discussion also includes D. poseidon Hu & Liang, 2021 from Taiwan. The phylogenetic relationships of this genus from Japan based on mitochondrial DNA sequences are discussed.  

Evolution of cephalic structures in extreme myrmecophiles: a lesson from Clavigeritae (Coleoptera: Staphylinidae: Pselaphinae)

Pselaphinae is a large subfamily, comprising over 10 000 species of the megadiverse Staphylinidae (rove beetles). A remarkable feature of this group is the extreme structural diversity of different body regions, especially the head and its appendages. Within Pselaphinae, Clavigeritae stand out as a clade of highly specialized myrmecophiles. We examined internal and external head structures of the clavigerite species Diartiger kubotai Nomura, using state-of-the-art techniques. The cephalic morphology indicates in a phylogenetic context that the loss of eyes in some Clavigeritae was the latest of major evolutionary changes. We compiled the largest set of morphological data ever scored for the subfamily, comprising 155 characters of the head. Parsimony analyses and Bayesian inference yielded a similar phylogenetic pattern, largely congruent with results published previously. We retrieved Pselaphinae as a clade, and Faronitae as sister to all remaining groups of the subfamily. Faronitae are followed by a "Euplectitae grade" and non-monophyletic Goniaceritae, Batrisitae and Pselaphitae. Clavigeritae are monophyletic, but have evolved within the pselaphite grade. The enigmatic Colilodion Besuchet, recently shifted from Clavigeritae to a paraphyletic Pselaphitae, was placed as sister to extant clavigerites based on an array of cephalic synapomorphies. The current classification of Pselaphinae is unstable and deep changes should be made maintaining only monophyletic units, whereas most of the supertribes are paraphyletic. Characters of the head, with a concentration of mouthparts and sensory structures, and essential parts of the digestive tract and the nervous system, are highly informative phylogenetically. Study of internal structures, presently still at a very preliminary stage, obviously is essential for understanding the evolution of Pselaphinae. Future genetic investigations may reveal mechanisms behind the unique structural megadiversity in this exceptional group of rove beetles.

Tachyporinae Revisited: Phylogeny, Evolution, and Higher Classification Based on Morphology, with Recognition of a New Rove Beetle Subfamily (Coleoptera: Staphylinidae)

Simple Summary

The rove beetle subfamily Tachyporinae has been suggested to be polyphyletic for the last half century but there are no previous studies conducting phylogenetic analysis on this group specifically. Here, the most comprehensive tachyporine phylogeny is shown, which again rejects the monophyly of Tachyporinae and its largest tribe Tachyporini. A revised classification of Tachyporinae is proposed here based on observation of morphological characters and their phylogenetic analyses. This backbone phylogeny will be a framework for further evolutionary and ecological studies.

Abstract

Tachyporinae are one of the most phylogenetically problematic subfamilies in the mega-diverse rove beetle family Staphylinidae. Despite its high diversity and abundance in forest micro-environments, with over 1600 species worldwide, several previous studies had refuted the monophyly of this subfamily and its largest tribe, Tachyporini. Based on the results of morphology-based phylogenetic analyses and direct examination of specimens encompassing two extinct and all forty extant genera, a new suprageneric classification of Tachyporinae is proposed here, with the removal of the tribe Mycetoporini into a newly recognized subfamily Mycetoporinae stat. nov. Four tribes with two subtribes are arranged within Tachyporinae sensu nov.: Tachyporini sensu nov. (Tachyporina stat. nov., sensu nov. and Euconosomatina stat. rev., sensu nov.), Vatesini sensu nov., Deropini, and Tachinusini stat. rev., sensu nov. (= Megarthropsini syn. nov.). Urolitus syn. nov. is placed as a junior synonym of Sepedophilus. Additionally, Palporus stat. nov. is raised to a distinct genus from a subgenus of Tachyporus sensu. nov., and †Mesotachyporus syn. nov. is synonymized with the latter. Mycetoporine Bobitobus stat. rev. is resurrected from synonymy with Lordithon sensu nov., and considered as a valid genus. My revised classification provides a novel framework for taxonomic inventories and ecological studies of these groups.