Cretaceous origin of the unique prey-capture apparatus in mega-diverse genus: stem lineage of Steninae rove beetles discovered in Burmese amber

Abstract

Stenus is the largest genus of rove beetles and the second largest among animals. Its evolutionary success was associated with the adhesive labial prey-capture apparatus, a unique apomorphy of that genus. Definite Stenus with prey-capture apparatus are known from the Cenozoic fossils, while the age and early evolution of Steninae was hardly ever hypothesized. Our study of several Cretaceous Burmese amber inclusions revealed a stem lineage of Steninae that possibly possesses the Stenus-like prey-capture apparatus. Phylogenetic analysis of extinct and extant taxa of Steninae and putatively allied subfamilies of Staphylinidae with parsimony and Bayesian approaches resolved the Burmese amber lineage as a member of Steninae. It justified the description of a new extinct stenine genus Festenus with two new species, F. robustus and F. gracilis. The Late Cretaceous age of Festenus suggests an early origin of prey-capture apparatus in Steninae that, perhaps, drove the evolution towards the crown Stenus. Our analysis confirmed the well-established sister relationships between Steninae and Euaesthetinae and resolved Scydmaeninae as their next closest relative, the latter having no stable position in recent phylogenetic studies of rove beetles. Close affiliation of Megalopsidiinae, a subfamily often considered as a sister group to Euaesthetinae + Steninae clade, is rejected.

First and oldest Leptochirini rove beetles illuminate diverse cephalic structures in the Cretaceous (Coleoptera: Staphylinidae: Osoriinae)

“…Convergence was judged to have occurred when the standard deviation (SD) of split frequencies dropped below 0.01. Additionally, the convergence and the examination of the potential scale reduction factor (PSRF) values were determined by the output (Żyła et al ., ). Convergence of both runs was also visualized in tracer v 1.6 (Rambaut et al ., ).…”

“…Nodes with posterior probability (PP) > 0.95 were judged to be strongly supported, with those with PP = 0.90–0.94 judged to be moderately supported, and those with PP = 0.85–0.89 weakly supported, as in Żyła et al . (). The tree was visualized and edited in figtree v1.4.2 (Rambaut, ) and Photoshop elements 15.…”

Phylogeny of the rove beetle tribe Gymnusini sensu n. (Coleoptera: Staphylinidae: Aleocharinae): implications for the early branching events of the subfamily

“…(). Beetles are one of the most diverse insect groups in Burmese amber (Ross et al ., ), and 14 staphylinid subfamilies are represented in this deposit (Yamamoto, ; Żyła et al ., ). As the Tachyporine group of subfamilies, only four species in four genera are known to date (Cai & Huang, ; Yamamoto, ; Yamamoto et al ., ; Cai et al ., ).…”

The past and the present through phylogenetic analysis: the rove beetle tribeOthiini now and 99 Ma

“…A great majority of the past systematic work in Staphylinidae, even when phylogeny‐based, has been done without the consideration of fossils. However, the use of fossils in rove beetle systematics is now becoming a trend, which is showing promising results (Solodovnikov et al ., ; Jałoszyński, ; Parker, ; Yamamoto et al ., ; Yamamoto & Maruyama, ; Żyła et al ., ).…”

“…In this light, it is very exciting to find two well‐preserved fossil species from Cretaceous Burmese amber, which also combine characters of Staphylininae and Paederinae and overall resemble members of Othiini, one of the less diverse but phylogenetically understudied tribes of Staphylininae. Due to a burst of recent studies of its well preserved inclusions, Burmese amber is becoming one of the world's most important sources of Staphylinidae fossil specimens, with representatives of most subfamilies already discovered: Aleocharinae (Cai & Huang, ; Yamamoto et al ., ; Yamamoto & Maruyama, ; Cai et al ., ), Dasycerinae (Yamamoto, ), Euaesthetinae (Clarke & Chatzimanolis, ), Megalopsidiinae (Yamamoto & Solodovnikov, ), Micropeplinae (Cai & Huang, ), Osoriinae (Cai & Huang, ), Oxytelinae (Lü et al ., ), Oxyporinae (Yamamoto, ; Cai et al ., ), Proteininae (Cai et al ., ), Pselaphinae (Parker, ), Scydmaeninae (Chatzimanolis et al ., ; Cai & Huang, ; Jałoszyński et al ., , , ; Yin et al ., ), Solieriinae (Thayer et al ., ), Steninae (Żyła et al ., ), and Tachyporinae (Yamamoto, ). Interestingly, these two presumed Othiini are the first known representatives of the Staphylininae found in Burmese amber.…”