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The first fossil tumbling flower beetle larva is a symphytan (Hymenoptera)
Jan BATELKA, & Michael S. ENGEL
A correction is provided regarding the identity of a fossil larva recently reported to represent the first Cretaceous record of its kind for the tenebrionoid family Mordellidae (Coleoptera, tumbling flower beetles). A review of the description of the specimen, however, reveals it to be a larval symphytan (order Hymenoptera), and likely of the family Pamphiliidae. The evidence for the revised identification is summarized.
The larva reported as a tumblingflower beetle by Zippel et al. (2022) does not possess characters of Coleoptera and particularly lacks those traits of Polyphaga, to which Mordellidae belongs. Instead, its habitus and morphology (antennae, legs, number of abdominal segments, modified segment X, subanal appendages, and unusually prolonged postcornus) clearly indicate its placement among the early diverging Hymenoptera. Furthermore, the combination of
characters present is most indicative of the Pamphiliidae (as noted above). Accordingly, it would be worthwhile to undertake a new revision of the fossil, speci fically looking for additional traits that may shed further light on its phylogenetic placement, particularly among pamphiliids. Pamphiliids include a lineage of conifer-feeding species, as well as angiosperm-associated genera. Thus, this fossil from a pivotal period in thefloral shift between a gymnosperm- to an angiosperm-dominated world could prove insightful into the transition between hosts in this lineage of saw flies.
...Given the misidenti fication, the hypotheses presented
by Zippel et al. (2022) regarding a possible association of the larva with wood or fungi and its contribution to the decomposition of plant matter are unfounded. The larvae of most sawflies, particularly those of the early diverging families, have phytophagous larvae that live externally on their host, feeding on plant foliage or the needles of conifers, and in the case of pamphiliids include species that may roll leaves or build tents from leaves united by
silk, and can at times live gregariously. The comparatively long legs of the fossil larva are anatomically unsuitable for tunneling in any kind of wood or herbaceous tissues, and are instead typical of a pamphiliid, which uses these to move about as well as to help bring together plant material to be rolled or spun together into a tent. It is only the more derived lineages of symphytans, such as the stem sawflies (Cephidae) or the woodwasps (Siricidae and Xiphydriidae) that live within stems or wood, while the Orussidae are parasitic on xylophagous insects. These families can be excluded on the basis of many traits, most notably the reduction or absence of true legs owing to the movement of the larvae within plant tissues or wood, or because of their parasitoidism.
https://ivanov-p.livejournal.com/313631.html
