O Stigmatomyces baeri, where art thou?
I am a mycologist, and one could argue that I am also an entomologist and a mammalogist. I work quite a bit with insects and with bats. I described a fossil beetle and I am in the process of describing a Neotropical bat fly (with my friend and collaborator Dr. Thomas Hiller). I have experience with mistnetting for bats, and I was invited to coauthor a data paper on bat conservation. This is all great fun, but if there is one thing I am not, it is a dipterologist. And for this following project, I am going to need some help from experts who work with flies. So let’s start at the start. I have decidate a lot of my time to studying Laboulbeniales microfungi, which are ectoparasites of arthropods. Most Laboulbeniales are found on beetles (80%) and flies (10%). On flies, representatives of several genera have been reported: Arthrorhynchus, Dimeromyces, Gloeandromyces, Nycteromyces (genera that are exclusively associated with bat flies); Appendiculina, Fanniomyces, Laboulbenia, and Stigmatomyces. Of those genera, Stigmatomyces is the largest with as many as 171 described species.
The type species of Stigmatomyces is S. baeri, which is found on Musca spp. (Muscidae) in Europe (thus far known in Austria, Czech Republic, Finland, Germany, Poland, Russia, Switzerland, and The Netherlands). Unfortunately, no sequences are available for S. baeri and so we do not know for sure where it belongs, that is, to which genus. Stigmatomyces is heterogeneous and it is possible that multiple genera are “hidden” within this name. Indeed, only recently, Appendiculina, an old name that had fallen in disuse, was reinstated based on molecular phylogenetic evidence. Appendiculina now includes species that had long been accepted in Stigmatomyces (sensu lato = in the broad sense).
Phylogenetic reconstruction of a two-locus sequence dataset, showing that Stigmatomyces sensu lato consists of four clades (colored).
The above tree includes all publicly available sequences of Stigmatomyces. You will see that clade III is comprised of species of Gloeandromyces—as mentioned before, these are species that occur exclusively on bat flies, which are bloodsucking ectoparasites of bats. Gloeandromyces species are morphologically very different from species of Stigmatomyces. There is also a genetic “barcode gap” of 3.56–4.17% marking inter- from intra-generic variability. It is fair to regard Gloeandromyces as an independent radiation on Neotropical bat flies. This means that Stigmatomyces sensu lato is a prime example of a paraphyletic clade, a group of organisms including the group’s last common ancestor and all descendants of that ancestor excluding a few—typically only one or two—monophyletic subgroups, in our case Gloeandromyces.
To resolve this taxonomic issue, we reinstated the genera Appendiculina (for the species in clade II) and Fanniomyces (for the species in clade I) within Stigmatomyces sensu lato in Haelewaters et al. (2020). Stigmatomyces sensu stricto (= in the strict sense) is represented by clade IV in the above phylogenetic tree. This situation needs confirmation by the inclusion of sequences of Stigmatomyces baeri, the type species of the genus. As long as these data are not available it is impossible to predict which of the current and potentially more clades in this diverse group should carry the name Stigmatomyces sensu stricto.
Indeed, knowing where the type species belongs is important for future studies in taxonomy and systematics! As a result, we are looking for collaborators that have sampled or can sample specimens of Musca spp. (Diptera, Muscidae) with fruitbodies of Stigmatomyces sensu lato. If you can contribute to our project, please get in touch! In return, we offer coauthorship on the resulting paper.
Pictures of flies infected with Laboulbeniales can be found here, here, here, and here. In addition, Figure 4 in Rossi et al. (2013) shows more in-situ pictures of infected flies.
References
Haelewaters D, Dima B, Abdel-Hafiz BII, Abdel-Wahab MA, Abul-Ezz SR, Acar I, Aguirre-Acosta E, Aime MC, Aldemir S, Ali M, Ayala-Vásquez O, Bakhit MS, Bashir H, Battistin E, Bendiksen E, Castro-Rivera R, Çolak ÖF, De Kesel A, de la Fuente JI, Dizkırıcı A, Hussain S, Jansen GM, Kaygusuz O, Khalid AN, Khan J, Kiyashko AA, Larsson E, Martínez-González CR, Morozova OV, Niazi AR, Noordeloos ME, Pham THG, Popov ES, Psurtseva NV, Schoutteten N, Sher H, Türkekul İ, Verbeken A, Ahmad H, Afshan NS, Christe P, Fiaz M, Glaizot O, Liu J, Majeed J, Markotter W, Nagy A, Nawaz H, Papp V, Péter Á, Pfliegler WP, Qasim T, Riaz M, Sándor AD, Szentiványi T, Voglmayr H, Yousaf N, Krisai-Greilhuber I. 2020. Fungal Systematics and Evolution 6. Sydowia 72: 231-356. https://doi.org/10.12905/0380.sydowia72-2020-0231 [pdf]
Rossi W, Santamaría S, Andrade R. 2013. Notes on the Laboulbeniales (Ascomycota) parasitic on Diptera from Portugal and other countries. Plant Biosystems 147: 730-742. https://doi.org/10.1080/11263504.2012.753132 [pdf]
