Myrmicium schroeteri?

Myrmicium is a relatively common fossil insect from the Solnhofen Limestone (Carpenter, 1932), classified as a kind of sawfly, which belongs to the Hymenoptera order, along with ants, bees, and wasps. It is thought to have been similar to horntails, a group of modern sawflies that may appear similar to hornets but differ from them by having a broad connection between the thorax and abdomen (Freitas et al., 2020). The specimen, preserved as a cast with slightly darker coloration than the surrounding sediment, shows the characteristic long antennae, two pairs of wings, and the general habitus of sawflies.

Horntails do not have stingers and live solitary lives, in contrast to social hymenopterans. They burrow into decaying wood and feed on fungi growing on the wood. It is possible that this fossil species had similar habits (Freitas et al., 2020).

The formal systematization of the Solnhofen material attributed to Myrmicium is complicated by the general lack of preservation of fine diagnostic anatomical attributes, such as wing venation, and a considerable size range (e.g., forewing size: ~2.5–6 cm), leading to uncertainty about the number of distinct species to be erected (Carpenter, 1932; Ponomarenko, 1985; Rasnitsyn et al., 1998). Freitas et al. (2020) suggest the use of M. schroeteri as a polymorphic species to encompass all variability observed in the Solnhofen specimens in the absence of better-preserved material, and their suggestion is tentatively followed here. It is also worth mentioning that some Myrmicium fossils have been described in the literature using the synonym Pseudosirex (Carpenter, 1932; Bartherl et al., 1990).

Myrmicium has been found in Jurassic rocks of Germany, as well as Cretaceous rocks of Brazil (Crato Formation) and England (Paleobiology Database, n.d.).

References:

Barthel K.W., Swinburne N.H.M., Conway Morris, S., 1990. Solnhofen: A Study in Mesozoic Palaeontology. Cambridge: Cambridge University Press.

Carpenter, F.M., 1932. Jurassic insects from Solenhofen in the Carnegie Museum and the Museum of Comparative Zoology. Annals of Carnegie Museum, 21(3), pp. 97-129.

Freitas, L.C., Rasnitsyn, A.P., Moura, G.J. and Mendes, M., 2020. New species of Myrmicium Westwood (Psedosiricidae= Myrmiciidae: Hymenoptera, Insecta) from the Early Cretaceous (Aptian) of the Araripe Basin, Brazil. Anais da Academia Brasileira de Ciências, 92(3), p. e20200479. doi:10.1590/0001-3765202020200479.

Paleobiology Database, No date. The Paleobiology Database. Available at: https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=txn:257595 (Accessed: November 2024).

Ponomarenko, A.G., 1985. Fossil insects from the Tithonian „Solnhofener Plattenkalke “in the Museum of Natural History, Vienna. Annalen des Naturhistorischen Museums in Wien. Serie A für Mineralogie und Petrographie, Geologie und Paläontologie, Anthropologie und Prähistorie, 87(A), pp. 135-144.

Radnitsyn, A.P., Jarzembowski, E.A. and Ross, A.J., 1998. Wasps (Insecta: Vespida= Hymenoptera) from the Purbeck and Wealden (Lower Cretaceous) of southern England and their biostratigraphical and palaeoenvironmental significance. Cretaceous Research, 19(3-4), pp. 329-391. doi:10.1006/cres.1997.0114.