The Plecoptera – who are they? The problematic placement of stoneflies in the phylogenetic system of insects

Abstract

There is no consensus about the relations of Plecoptera with other insects. Very different sistergroup relationships have been proposed in the literature, several of which are discussed. The phylogenetic analysis is hampered by the diversity among Plecoptera. In the literature, traits of particular subgroups of Plecoptera have sometimes been mistaken as typical of the entire order. A plea for revived interest in plecopteran morphology is made in order to document the existing diversity and to establish the ground pattern of important structures for meaningful comparisons with other insects. A possible sistergroup relationship between Plecoptera and the remaining Neoptera, on the one hand, and a sistergroup relationship with the Polyneoptera on the other hand, seem most likely. Suggested close relationships of Plecoptera with Embioptera and Phasmatodea are refuted. Molecular data so far also failed to provide robust phylogenetic hypotheses for the placement of Plecoptera.Keywords: phylogenetic relations; Ephemeroptera; Neoptera; Polyneoptera; Embioptera; Phasmatodea Introduction Establishing the identity of Plecoptera and distinguishing them from other insects was the cardinal problem when early students began to perceive the multitude of insects and tried to order the astounding diversity. There was enormous progress from the earliest presentation of a stonefly as a nameless beautiful natural object (Hoefnagel 1592) to the detailed works by Burmeister (1839) and Pictet (1841) who were familiar with many details of adult and larval morphology, ecology and behaviour of Plecoptera. Following their studies, Plecoptera were no longer confused with other insects.However, the question where in the insect system the Plecoptera belong, what their closest relatives are, remains unanswered today. I do also not know but would like to discuss some suggested relations. The literature offers different answers to the above question but only work applying sound phylogenetic methodology (use of only homologous characters, conscientious distinction of plesiomorphic from apomorphic character states, conclusions based on only the latter) are relevant. The result of such work is a hypothesis of relations which becomes increasingly probable as efforts to falsify it fail, but it can never be proven.

Insect Phylogenomics: Exploring the Source of Incongruence Using New Transcriptomic Data

“…Herein, especially the phylogenetic position of Plecoptera (Zwick 2009) and Zoraptera (Yoshizawa 2007) is far from settled (table 1). Both of them belong to the most phylogenetically ambiguous insect orders and even their placement within the polyneopteran lineage is still under discussion.…”

The internal reproductive system of Antarctoperlaria (Plecoptera), with special reference to the organisation of the larval ovarioles

“…Stoneflies (Plecoptera) are generally regarded as a basal taxon (Hennig 1981;Zwick 2000Zwick , 2009 of Neoptera or Polyneoptera, but the phylogenetic relationships between the Plecoptera and orthopteroid, blattopteroid or ''Dermaptera-like'' lineages are still not resolved (Zwick 2000(Zwick , 2009. In this respect, the internal organs of insects, especially reproductive organs, could be useful for phylogenetic analyses.…”

“…Plecoptera (stoneflies) are generally considered as one of the most primitive taxa within pterygote insects (see Hennig 1981, Zwick 2000, 2009. The order is classified into two suborders reflecting the basal sister groups Arctoperlaria (of possibly Laurasian origin, inhabiting the Northern Hemisphere) and Antarctoperlaria (of possibly Gondwanian origin, inhabiting the Southern Hemisphere) (Zwick 2000).…”

The structure and ultrastructure of the egg capsule of Brachyptera risi (Plecoptera, Nemouroidea, Taeniopterygidae) with some remarks concerning choriogenesis

“…Moreover, until the ultrastructural studies on the euholognathan egg coverings were done, a similar, erroneous opinion was there that, in the Euholognatha, eggs are enveloped only with a soft, glutinous, structure‐less, thin sheath. However, Zwick () concluded by his results of the ultrastructural investigations on egg capsule in Protonemura intricata that the chorion is, in fact, present and even a micropyle was revealed in this euholognathan species (Rościszewska, ). Similar results were reported for other euholognathan stonefly, Leuctra autumnalis (Poprawa et al, ).…”