The evolutionary history of Paederinae, one of the largest subfamilies in Staphylinidae, still remains poorly understood. For a better understanding, fossils are of major importance. In this study, the first fossil representative of the tribe Paederini in mid-Cretaceous Burmese amber from the Kachin State of northern Myanmar is described. The examined fossil could be assigned to the subtribe Cryptobiina, which makes it the first formally described fossil of the subtribe. The external morphology of the specimen was examined and compared to all recent genera currently assigned to the subtribe. This led to the description of the new genus and species Cretobius fangornis gen. et sp. nov. presented in this study. Comparison with recent taxa indicates that the palaeoenvironment of the amber forest was humid and tropical. The finding supports the hypothesis of tropical climate in the Cretaceous Kachin amber forest and the idea of an earliest separation of the Burma Terrane from Gondwana in the Early Cretaceous.

Gerke L. & Żyła D. in collaboration with: Yamamoto S.

#amber #taxonomy

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The Neotropical genus of myrmecophilous beetles, Ecitonides Wasmann, 1894 (Staphylinidae: Paederinae: Lathrobiini), currently includes nine valid species distributed in French Guiana, Suriname, Brazil, Peru, Paraguay, and Argentina. Members of this genus are notable for the tuberculate ornamentation on the head, thorax, and abdomen. Although little is known about the biology of these beetles, there are records of association with different species of army ants (Labidus Jurine, 1807 and Nomamyrmex Borgmeier, 1936). In this study, a detailed comparative morphological study of all available species for study was conducted, descriptions of two new species, Ecitonides colossus sp. nov. and Ecitonides splendidus sp. nov., are provided, and lectotypes for Ecitonides brevicornis Wasmann, 1900 and Ecitonides spectabilis Borgmeier, 1932 are designated. Diagnoses, illustrations, and photographs are given; an identification key is provided for all 11 species as well as new geographic distribution data. The aim of this study is to provide morphological data that will serve as a tool for a future investigation of the phylogenetic position of the genus and facilitate species recognition through diagnostic morphological characters and an identification key.

Montanhini A. & Żyła D. in collaboration with: Biffi G.

#morphology #myrmecophily #neotropics #taxonomy

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Morphological characters are one of the bases for describing any organismal group and comparative morphology plays an important role in taxonomy, systematics, and evolutionary research. Yet, in many groups, especially highly diverse, the terminology and homology of morphological structures are poorly understood. One of such examples is the mega-diverse group of animals, rove beetles (Staphylinidae), where comparative studies are very rare, both across the subfamilies and within them. In this paper, we present our results of morphological examination of mesoventral sclerotisation across different subtribes and genera of Paederinae, which is one of the most diverse rove beetle subfamily. Additionally, we compare them with several representatives of Staphylininae and Xantholininae. We revise morphological terminology for the mesoventral area in Paederinae and propose a hypothesis for character homologisation within Paederinae and across the listed subfamilies. Our results are based on examination of representatives of 157 Paederinae genera and the major groups are illustrated by schematic drawings and SEM scans. Additionally, we introduce new characters with potential importance for subtribal level phylogenetic reconstruction of Paederinae relationships. This is the first comprehensive review of the mesoventral area for the subfamily.

Tokareva A. & Żyła D. 

#mesoventric sclerites #structural homology

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During our visits to museum collections, we encountered numerous specimens of undescribed species representing the Neotropical genus Neolindus Scheerpeltz, 1933 which was earlier thought to be rare. To address the knowledge gap in the genus, we studied the museum material that resulted in descriptions of 21 new species. Our work involves the redescription of the genus, descriptions of the new species, and an updated identification key to 39 previously described and new species. This research emphasises the importance of museum collections in advancing taxonomy and enriching biodiversity knowledge. With these contributions, the known number of species of Neolindus reaches 60, thereby enhancing data on the Neotropical rove beetles diversity. Additionally, we provide several new country records for the genus (Guyana, Mexico, Nicaragua, and Suriname), which widen its distribution, and new occurrence records for the described species of Neolindus.

Guzman Y. C., Tokareva A., Koszela K. & Żyła D. 

#neotropics #taxonomy #systematics

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This work adds a new eyeless species of the genus Micranops Cameron, 1913 (Staphylinidae, Paederinae, Scopaeina) to the endogean Coleoptera of the Bolivian fauna. The loss of eyes is usually associated with adaptations to subterranean habitats, although M. bolivianus Guzman & Żyła sp. nov. was collected from leaf litter. We also report new occurrences for the genus west of the Andes mountain range. Our work increases the number of known Neotropical Micranops species to seven and extends the known distribution range for the genus in South America.

Guzman Y. C. & Żyła D. 

#neotropics #taxonomy #systematics #phylogenetics

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The ecology of extinct species from the Cretaceous is largely unknown. Morphological features of specimens preserved in amber can help to reveal habitats and evolutionary strategies that occurred in fossil lineages. An unusually small rove beetle (Staphylinidae) from the subfamily Paederinae with a Y-shaped suture on the head and modified tarsi and antennae is newly described here as Midinudon juvenis Tokareva & Żyła gen. et sp. nov. We hypothesise that such a combination of characters represents the earliest example of paedomorphosis in Staphylinidae and discuss other possible reasons that could explain the small size and morphological modifications of the new species. We provide the results of total-evidence phylogenetic analysis and discuss the relationships of Midinudon juvenis Tokareva & Żyła gen. et sp. nov. within Paederinae.

Tokareva A., Koszela K. & Żyła D.  in collaboration with: Ferreira V. S. & Yamamoto S.

#paedomorphosis #amber #taxonomy #systematics #phylogenetics

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We describe a new genus and species of Paederinae rove beetles, Ruptor cordatus gen. et sp. nov., which lives in the arboreal nests of the termite Labiotermes labralis (Holmgren, 1906) in the Amazon lowlands of Peru. The morphology of Ruptor gen. nov. is highly derived, apparently due to its close association with the termite host, and thus, morphologically, the genus cannot be classified further than Lathrobiini incertae sedis. In order to address the sister-group relationships of Ruptor gen. nov., we conducted a molecular phylogenetic analysis based on seven gene fragments. The analysis indeed resolved the genus as a member of the tribe Lathrobiini and placed it nested within the informal clade of ‘Medonina and allied taxa’. We provide a morphological comparison of the new genus with all known myrmeco- and termitophilous representatives of the subfamily, and to the extent possible, we illustrate other relevant and poorly known Neotropical Paederinae inquilines.

D. Żyła in collaboration with: A. Bogri, A. K. Hansen, J. J. Shaw, J. Kypke & A. Solodovnikov

#taxonomy #systematics #phylogenetics #inquiline

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Acrostilicus Hubbard, 1896 and Pachystilicus Casey, 1905 are North American genera known from only one and two species, respectively, and have never been a subject of a modern revision. In fact, Acrostilicus was not even properly described as its author provided only a sketchy diagnosis of the genus and species. Here, we provide a redescription of the genus Acrostilicus and its species and illustrate the habitus and male genital features. For the first time, we also redescribe Pachystilicus and its two species, and provide their differential diagnoses. Additionally, we tested the phylogenetic position of both genera. They were scored into a morphological matrix supplemented with molecular data and the analyses were run using Bayesian inference and maximum likelihood methods. A total of 119 morphological characters and 4859 bp of nuclear (28S, TP, Wg, CADA, CADC, ArgK) and mitochondrial (COI) sequences were analysed for 46 taxa. The results confirmed that both Acrostilicus and Pachystilicus are members of the subtribe Stilicina, but at the same time challenged the monophyly of the subtribe in its current composition. Additionally, we provided further evidence for non-monophyly of the subtribe Medonina and discussed the biology of Acrostilicus and Pachystilicus.

D. Żyła, A. Tokareva & K. Koszela

#taxonomy #systematics #phylogenetics

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The myrmecophilous Paederinae rove beetle genus Megastilicus Casey, 1889 from North America is reviewed based on museum specimens. Prior to this study, the genus was monotypic with one species Megastilicus formicarius Casey, 1889 described. Here, we provide a redescription of the genus and the type species, designate a lectotype, and provide pictures of habitus and illustrations of the aedeagus and genital segments. Additionally, we describe a new species for the genus, Megastilicus iowaensis sp. nov., include an identification key to the two species and present the distribution map of both of them, including new state records. We discuss the assignment of the genus to the subtribe Stilicina based on morphological features.

D. Żyła & K. Koszela

#taxonomy #systematics 

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