Untangling the evolution of soldier beetles (Coleoptera: Cantharidae) and the evaluation of the morphological phylogenetic signal in a soft‐bodied elateroid lineage

Abstract

This study addresses the long‐standing uncertainty about the internal classification of soldier beetles (Elateroidea: Cantharidae). Four datasets were compiled and analysed: 66 genes for 14 terminals, 15 mtDNA genes for 79 terminals, one mtDNA and two rRNA genes for 217 terminals, and barcodes for 576 terminals. Based on congruent topologies, Chauliognathinae is proposed as a sister to the remaining Cantharidae, followed by the redefined Malthininae (including Tytthonyxini), the paraphyletic “dysmorphocerine” lineages (Dysmorphocerinae sensu stricto and Heteromastiginae subfam. nov.), and Silinae + Cantharinae as a terminal clade. The present phylogeny supersedes earlier morphology and short‐fragment molecular hypotheses that have not converged on a consensus. Few morphological characters corroborate the DNA‐based relationships (see the adults and larval keys). However, morphology‐based hypotheses have relied on a few informative characters, and no evidence strongly rejects the preferred molecular topology. The interpretation of morphological characters and uncertain polarity resulting from the high phenotypic disparity of Elateroidea are discussed in detail. The dated phylogeny hypothesizes the earliest split within the Cantharidae in the Berriasian stage (Early Cretaceous, ~141 Myr) and the diversification of most extant subfamilies and tribes already in the Late Cretaceous. The most diverse subfamily, Cantharinae, represents a delayed radiation that started during the Eocene climatic optimum, 55.5 Myr. The late origin of Cantharinae questions the classification of Cretaceous Cantharidae as members of Cantharinae. Instead, the results suggest their deeper rooting after separating from dysmorphocerine lineages and before the node between Cantharinae and Silinae.

On the nomenclatural status of type genera in Coleoptera (Insecta)

“…Family-group name: HETEROMASTIGINAE Motyka, Biffi & Bocák in Motyka et al, 2023b : 559. Stem: Heteromastig -.…”

Rediscovery of <i>Malthesis ater</i> Motschulsky, 1853 and a catalog of the genus <i>Malthesis</i> Motschulsky, 1853 (Coleoptera, Cantharidae)

“…In the current classification (Magis and Wittmer 1974, Brancucci 1980, Motyka et al 2023, two lineages of genera are recognized in Chauliognathini. In the first, the elytra are extremely reduced, covering up to two abdominal tergites and exposing most of the hind wings, e.g., Maronius Gorham, 1881, Paramaronius Wittmer, 1963, Lobetus Kiesenwetter, 1852, Macromalthinus Pic, 1919, etc.…”

Three new brachelytrous Discodon and Polemius (Brachypolemius) from Peru (Coleoptera, Cantharidae, Silinae)

“…GeneRiC key to maLe peRuvian siLinae Silinae can be recognised among Cantharidae by: -maxillary palpomeres I-III of unequal length; -tibial spurs robust and clearly visible; -fourth tarsomere usually split across at the base; -abdomen with eight visible segments, IX and X invaginated; -division of the male sternite VIII reaching the base; -male sternite IX symmetrical when developed. The females are hard to distinguish since the diagnose of genera depends on male's features (Constantin, 2008;motika et al, 2023). Note on the collector.…”