|Holotype of Urtea graeca, mustachioed with silly maxillary palporgans (Paulus, 2004)|
|Male Iberobaenia minuta; scale bar=1 mm.|
In appearance, Iberobaenia is clearly elateroid in both known ontogenetic stages. The tiny, soft-bodied male imagos resemble, in their reduced mouthparts and lack of elytral costae or tubercles, other elateroid lineages that have undergone miniaturization relative to the superfamily's norm. Their habitus is most comparable to such genera as Paradrilus (Omalisidae) and Antennolycus (Lycidae), but iberobaeniids differ from these in their hypognathous* mouthparts (in contrast to omalisids), lack of a pronotal margin (differing from lycids and non-paradriline omalisids in this respect), and uncompressed legs (here being distinct from otherwise comparable lycids). Larvae are not dorsoventrally flattened and lack urogomphi† (unlike their lycid counterparts), with robust convergent mandibles (Bocak et al., 2016).
|Female Duliticola paradoxa (Lycidae): image by Bernard Dupont|
While Iberobaenia is certainly distinctive in that it cannot be confidently placed in any elateroid family, I personally doubt that its assignment to an entirely new one will hold under future acquisition of more genetic data. From a morphological standpoint, the proposed Iberobaeniidae lacks any nomothetic‡ characters, meaning that we must rely upon the phylogenetic analysis of Bocak et al. (2016) for justification of its ranking as family. This phylogeny (with Elaterophanes and Aphodiites, which are respectively the oldest known elateriforms and scarabaeiforms, as calibration priors) suggests that Iberobaenia branched from its most recent common ancestor in the mid-Jurassic: I wonder how much water mitogenomes (from which half of the data used in this analysis were drawn) hold at that timescale, given their famously rapid rate of mutation (Brown et al., 1979).
As with so many things in our world, more data would be welcome.
*With mouthparts directed downwards.
†Superficially cercus-like processes on the terminal segments of some beetle larvae.
‡One particular feature that is unique to the taxon in question.
Andujar, C.; Arribas, P.; Linard, B.; Kundrata, R.; Bocak, L. and Vogler, A. P. (2016). The mitochondrial genome of Iberobaenia (Coleoptera: Iberobaeniidae): first rearrangement of protein-coding genes in the beetles. Mitochondrial DNA Part A: DNA Mapping, Sequencing, & Analysis; 28(2), 156-158. Retrieved 3/3/17 from http://www.tandfonline.com/doi/abs/10.3109/19401736.2015.1115488?journalCode=imdn21http://www.tandfonline.com/doi/abs/10.3109/19401736.2015.1115488?journalCode=imdn21
Bocak, L.; Kundrata, R.; Fernandez, C. A.; and Vogler, A. P. (2016). The discovery of Iberobaeniidae (Coleoptera: Elateroidea): a new family of beetles from Spain, with immatures detected by environmental DNA sequencing. Proceedings of the Royal Society of Britain, 283, 1-7. Retrieved 3/5/17 from https://pdfs.semanticscholar.org/e4da/1e1282ecb9a5b438ed0de3bb9193dc1ea10e.pdf
Brown, W. M.; George, M. Jr.; and Wilson, A. C. (1979). Rapid evolution of animal mitochondrial DNA. Proc. Nat. Acad. Sci. USA, 79, 1967-1971.
Cameron, S. L. (2014). Insect mitochondrial genetics: implications for evolution and phylogeny. Annual Review of Entomology, 59, 95-117.
Pace, R. (1975). An exceptional endogeous beetle: Crowsoniella relicta n. gen. n. sp. of Archostemata Tetraphaleridae from central Italy. Bolletino del Museo Civico di Storia Naturale, Verona; 2, 445-458.
Paulus, H. F. (2004). Urtea graeca nov. gen. et nov. spec., der erste Vertreter tropischen Atractocerinae in Europa sowie eine Beschreibung von Hymaloxylon aspoecki nov. spec. aus Yunnan (China) (Coleoptera, Cucujiformia, Lymexylidae, Atractocerinae nov. status). Denisia, 277-290. Retrieved 2/11/17 from http://www.zobodat.at/pdf/DENISIA_0013_0277-0290.pdf