The systematics of Dysmorphocerinae (Cantharidae) based on larvae

Abstract

Dysmorphocerinae is a subfamily of Cantharidae erected for a group of genera with a mainly gondwanan distribution whose adult forms could not be reliably assigned to any other subfamily. The systematic position and monophyly of Dysmorphocerinae remains questionable, as recent molecular and morphological studies have produced conflicting results. Despite the importance of immature morphology for characterising lineages of Cantharidae, so far, the larvae of only two dysmorphocerine species had been briefly described: Neoontelus sp., from New Zealand, and Afronycha picta (Wiedemann), from South Africa. Their morphologies considerably differ from one another, and the larvae cannot be readily attributed to any subfamily, as usually occurs with cantharid larvae. Here, we fully describe for the first time the larvae of Asilis Broun (New Zealand) and Plectonotum laterale Pic (Brazil) and redescribe Neoontelus Wittmer (New Zealand). We also diagnose larvae of Heteromastix Boheman (Australia) and A. picta. Dysmorphocerinae cannot be clearly diagnosed because each genus has a unique combination of features, though Neoontelus is the most divergent. We conclude that the Dysmorphocerinae may not be monophyletic with Plectonotum laterale, Asilis, Neoontelus, Heteromastix showing a closer relationship to Malthininae and Afronycha more aligned with Silinae or Cantharinae. The double gland openings present on the body of Neoontelus reported by Crowson (1972) are reinterpreted as a complex character involving a single posterior pore linked to a gland and an anterior sensillum that may serve as a trigger for the release of defensive chemicals. These are also reported in Asilis and Heteromastix and may be a potential synapomorphy for part of the Dysmorphocerinae. Neoontelus has a series of unique features, including a cotyliform glandular pore on abdominal segment IX.

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

“…The phallobase is extensive, sclerotized and ventrally expanded, and the styli and coxites are fused (Brancucci, 1980; Hsiao et al., 2021). The larvae have a strongly laterally projected nasale, with an elevated median tooth, antennomere 2 with large subapical sensorium, mandibles without a fringe of setae beneath the mesal channel and abdominal segment 9 without glandular pores (Biffi et al., 2022).…”

“…Abdomen with eight tergites and seven ventrites, abdomen and male genitalia never asymmetrical. The larvae of Heteromastiginae ( Heteromastix , Asilis , and Neoontelus ) have antennomere 2 with a large subterminal sensorium (shared with Malthininae and Neotropical Dysmorphocerinae) and large rounded sensilla flanking each thoracic and abdominal glandular pore (Biffi et al., 2022).…”

“…Plectonotum has antennomere 2 with a large subterminal sensorium, maxillary palpomeres 1–3 are subequal in length, and labial palpomere 1 is almost as long as antennomere 2. Alternatively, Afronycha has antennomere 2 with a terminal sensorium, maxillary palpomeres 2 is very long, antennomere 3 short and palpomere 2 is much longer than antennomere 2 (Biffi et al., 2022).…”