Molecular Phylogeny Reveals High Diversity, Geographic Structure and Limited Ranges in Neotenic Net-Winged Beetles Platerodrilus (Coleoptera: Lycidae)

Abstract

The neotenic Platerodrilus net-winged beetles have strongly modified development where females do not pupate and retain larval morphology when sexually mature. As a result, dispersal propensity of females is extremely low and the lineage can be used for reconstruction of ancient dispersal and vicariance patterns and identification of centres of diversity. We identified three deep lineages in Platerodrilus occurring predominantly in (1) Borneo and the Philippines, (2) continental Asia, and (3) Sumatra, the Malay Peninsula and Java. We document limited ranges of all species of Platerodrilus and complete species level turnover between the Sunda Islands and even between individual mountain regions in Sumatra. Few dispersal events were recovered among the major geographical regions despite long evolutionary history of occurrence; all of them were dated at the early phase of Platerodrilus diversification up to the end of Miocene and no exchange of island faunas was identified during the Pliocene and Pleistocene despite the frequently exposed Sunda Shelf as sea levels fluctuated with each glacial cycle. We observed high diversity in the regions with persisting humid tropical forests during cool periods. The origins of multiple species were inferred in Sumatra soon after the island emerged and the mountain range uplifted 15 million years ago with the speciation rate lower since then. We suppose that the extremely low dispersal propensity makes Platerodrilus a valuable indicator of uninterrupted persistence of rainforests over a long time span. Additionally, if the diversity of these neotenic lineages is to be protected, a high dense system of protected areas would be necessary.

Phylogenomic analysis resolves the relationships among net‐winged beetles (Coleoptera: Lycidae) and reveals the parallel evolution of morphological traits

“…For example, neotenic Calopterini were placed to Leptolycini (Miller, ; Kazantsev, ), but the molecular analyses rejected such placement (Masek et al , ; Kalousova, ). Based on results from previous studies and our transcriptomic phylogeny (Figs A–C, S1–S6; Bocak et al , ; Masek et al , , ), we propose that the adult male morphology is considerably affected by the ontogenetic reprogramming that produces larviform females, and that common occurrences of parallel evolution could obscure morphological analyses.…”

“…Since then, larviform females have been identified in other lycid taxa. Additional presumed neotenics are currently known in a high number of males and their relationships, morphology and distribution indicate a possibility that conspecific females are larviform, although this hypothesis has not been verified (Crowson, ; Cicero, ; Bocak & Bocakova, ; Miller, ; Kazantsev, , ; Bocak et al , ; Masek et al , , ; McMahon & Hayward, ). We considered these taxa to be neotenic in our analysis in agreement with the opinion of the listed authors.…”

The discovery of Iberobaeniidae (Coleoptera: Elateroidea): a new family of beetles from Spain, with immatures detected by environmental DNA sequencing

“…Adult Iberobaenia differs from Lycidae by the filiform male antennae with a long antennomere 2, the absence of the sharp lateral edge and strengthening structures in the pronotum, the elytra without costae or tubercles, and the uncompressed legs ( figure 1a,b). Yet, some characters are shared between both families, such as the v-shaped phallobase that is similar to those in some Lyropaeini [34] and the short prosternum with two apical processes (although these are directed upwards; figure 1b). Females are absent in our sample and we suppose that they remain larviform or at least incompletely metamorphosed when sexually mature, with a short lifespan and cryptic lifestyle.…”

“…Convergences in these traits have to be seen in the context of miniaturization of males, i.e. sexually linked body size differentiation [34,35] and hypothesized to be a result of the K-and r-strategy of the respective sexes [4]. Miniaturization is linked to the absence of the pronotal carinae and elytral costae as strengthening structures.…”

“…Equally, various neotenic lineages of Lycidae and Omalisidae exhibit high endemism and relict occurrence [4,36], as found in Iberobaeniidae. Neotenic females are apterous and short-lived during the adult stage, and thus due to their limited dispersal, population persistence is predicted to require geological and climatic stability [35,39]. Additionally, the discovery of a new beetle family in Europe, only the second since the nineteenth century, emphasizes the need for the protection of natural habitats and, in combination with the high level of threat from human activities, justifies the designation of the western Mediterranean as a biodiversity hotspot [11].…”