Stigmatomyces entomophilus (Peck, 1885) Thaxt.

Mishustin, Ruslan I., Khodosovtsev, Alexander Y. & Rossi, Walter, 2024, New species and new records of Laboulbeniales (Ascomycota) from countries surrounding the Black Sea, Cryptogamie, Mycologie 20 (11), pp. 139-149 : 148

Stigmatomyces entomophilus (Peck, 1885) Thaxt.

EXAMINED MATERIAL. — Ukraine • Zakarpatska oblast , Uzhhorod district, Kamianitsa village; 48°36’21”N, 22°13’55”E; 20.VII.2023; leg. R. Mishustin; slide #L00472; on tergites of Drosophila (Drosophila) cf. funebris (Fabricius, 1787) (#i00391-1) .

ADDITIONAL EXAMINED MATERIAL. — Germany • Ober-Bayern, Schöngeising bei Fürstenfeldbruk “Ort”; 550 m alt.; 17.VI.1999; leg. W. Schacht on D. funebris (slides WR3386a & WR3386b).

KNOWN DISTRIBUTION. — This fungus is associated with species of Drosophila subsp. Drosophila ( Diptera , Drosophilidae ); records on other subspecies need confirmation. It is reported from America ( Bolivia, United States), Europe ( Austria, Czech Republic, Denmark, France, The Netherlands, United Kingdom), and from Africa ( Gabon, South Africa) ( Santamaría & Pedersen 2021). It was also reported from Jamaica under the synonym Stigmatomyces drosophilae Thaxt. ( Rossi 1998).

NOTES

The new findings of Stigmatomyces entomophilus forces us to take a position on the taxonomy of this species (and others in the same genus).

Stigmatomyces is a large genus including so far 156 species associated with flies ( Diptera ) ( Santamaría & Pedersen 2021). In a recent study ( Haelewaters et al. 2020), based on molecular phylogenetic analysis, the small genus Gloeandromyces Thaxt. was found nested within a clade including species of the genus Stigmatomyces . To resolve the recovered polyphyly of Stigmatomyces the species of this genus has been split into three genera. Although there is a degree of subjectivity in delimiting genera, and there are often multiple ways to name the clades of a phylogenetic tree, we argue that synonymizing Gloeandromyces with Stigmatomyces is a preferable choice to maintain monophyletic taxa. First of all, there aren’t any morphological or ecological characters that clearly distinguish the genera proposed by Haelewaters et al. (2020). In addition, Haelewaters et al. (2020) only analyzed nine Stigmatomyces species, representing less than 6% of the species assigned to this genus at present. Therefore, following the splitting of Stigmatomyces , there would be over 140 species (not analyzed by this study) that cannot be safely assigned to the various genera, pending a future molecular assessment. This is highly unlikely for many species, considering that about 50% of the described species of Stigmatomyces are known from the type series only. Second, the merge of Gloeandromyces with Stigmatomyces would require far fewer nomenclatorial changes compared to the splitting of Stigmatomyces into multiple genera. Gloeandromyces only include 10 species and assigning them to Stigmatomyces would leave no species in an undefined taxonomic position. Finally, it should also be mentioned that among the few species included in the molecular analysis of Haelewaters et al. (2020) it is not included the type species of the genus Stigmatomyces . This adds further taxonomic uncertainty because even the genus names attributed to the four clades by this study are provisional, pending the clarification of the phylogenetic position of the type species of the genus Stigmatomyces .

Based on the reasons stated above we reject the splitting of the genus Stigmatomyces and suggest instead the synonymy of the genus Gloeandromyces with Stigmatomyces . We further recommend that major systematic changes of the classification of the large genus Stigmatomyces should only be pursued when a large number of species are available for molecular phylogenetic analyses.

Our opinion on the split of the genus Stigmatomyces does not differ substantially from what was recently written on the same topic by Santamaría & Pedersen (2021: 251-252).