Higher‐level phylogeny of diving beetles (Coleoptera: Dytiscidae) based on larval characters

Abstract

A comprehensive higher-level phylogeny of diving beetles (Dytiscidae) based on larval characters is presented. Larval morphology and chaetotaxy of a broad range of genera and species was studied, covering all currently recognized subfamilies and tribes except for the small and geographically restricted Hydrodytinae, where the larva is unknown. The results suggest several significant conclusions with respect to the systematics of Dytiscidae including the following: monophyly of all currently recognized subfamilies, although Dytiscinae when considered in a broad context is rendered paraphyletic by Cybistrinae; currently recognized tribes are monophyletic except for Agabini, Hydroporini and Laccornellini; inter-subfamily and inter-tribe relationships generally show weak support, except for a few well supported clades; three distinct clades are recognized within Dytiscinae [Dytiscini sensu lato (i.e. including the genera Dytiscus Linnaeus and Hyderodes Hope), Hydaticini sensu lato, and Cybistrini]; and recognition of Pachydrini as a distinct tribe. Other less robust results include: Methlini sister to the rest of Hydroporinae; relative basal position of Laccornini, Hydrovatini and Laccornellini within Hydroporinae; close relationship of Agabinae and Copelatinae; Matinae nested deep within Dytiscidae, as sister to a large clade including Colymbetinae, Coptotominae, Lancetinae and Dytiscinae sensu lato; the sister-group relationship of Agabetini and Laccophilini is confirmed. The results presented here are discussed and compared with previous phylogenetic hypotheses based on different datasets, and the evolution of some significant morphological features is discussed in light of the proposed phylogeny. All suprageneric taxa are diagnosed, including illustrations of all relevant synapomorphies, and a key to separate subfamilies and tribes is presented, both in traditional (paper) format and as an online Lucid interactive identification key.

Evolution of the Juan Fernández diving beetle, Rhantus selkirki (Coleoptera, Dytiscidae)

“…The subfamily Colymbetinae is monophyletic in our analysis, in agreement with previous studies based on various data sets (Beutel, Ribera, & Bininda‐Emons, ; Burmeister, ; Michat et al., ; Miller, ; Miller & Bergsten, ; Morinière et al., ; Ribera, Hogan, & Vogler, ; Ribera et al., ). The support obtained was moderate (Figure ), and no unambiguous synapomorphies were discovered (Figure ).…”

“…We found some evidence for a clade comprising the genera Neoscutopterus J. Balfour‐Browne, 1943, Hoperius Fall, 1927, Meladema Laporte, 1835, Bunites Spangler, 1972, Nartus and Rhantus , in agreement with Michat et al. (). The support obtained for this grouping, as well as for its internal nodes, was weak, with the possible exception of a moderately supported clade Neoscutopterus + Hoperius .…”

Systematics of aquatic beetles (Coleoptera): current state and future directions

“…Dytiscinae, Agabini, Hydroporini), and the relationships among subfamilies differs substantially (e.g. Laccophinae being a highly nested, late diverging lineage in Miller & Bergson but sister to the remaining Dytiscidae in Michat et al, 2017).…”

“…provided a major attempt at a family-wide classification using a thoroughly sampled, six-gene dataset combined with adult morphology, which remains the most complete and robust estimate to date. Michat et al (2017) provide an independent estimate of dytiscid phylogeny based solely on larval characters. The larval phylogeny largely agrees with with regard to the monophyly of most tribes and subfamilies, though there are exceptions (e.g.…”

“…Of the 11 subfamilies and 19 tribes recognized currently within Dytiscidae, the larvae for only one subfamily, Hydrodytinae, remain unknown (Miller & Bergsten, 2016). Michat et al (2017) provide a comprehensive review and discussion of dytiscid larvae in a phylogenetic framework, as well as paper and online keys to the larvae of the subfamilies and tribes of the diving beetles of the world. The monumental work by Larson et al (2000) is also a good source of larval keys and illustrations, albeit focused on North America.…”