Phylogenetic placement of two species known only from resting spores: Zoophthora independentia sp. nov. and Z. porteri comb. nov. (Entomophthorales: Entomophthoraceae)

Authors: HAJEK, A.E. - Cornell University; GRYGANSKYI, A. - Duke University; BITTNER, T. - Cornell University; LIEBHERR, J.K. - Cornell University; LIEBHERR, J.H. - Cornell University; JENSEN, A.B. - University Of Copenhagen; MOULTON, J.K. - University Of Tennessee

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: The fungi of the Entomophthorales are pathogens of insects and other invertebrates that are typically classified primarily on the basis of their forcibly discharged, thin-walled, infective spores (conidia). Many of these fungi form thick-walled overwintering (environmentally resistant) resting spores, but these spores are rarely treated as having major taxonomic value unless their ONLY known spore states are these resting spores; these nearly 40 species have traditionally been placed in the genus Tarichium because of this seemingly anomalous mode of reproduction. Over several years there have been collections in the eastern United States of adult craneflies (Diptera: Tipulidae) that produce only a single generation per year, but that are infected by entomophthoralean fungi that produce only the thick-walled resting spores. Comparisons of gene sequences for several collections of these cranefly resting spores collected in Tennessee and, repeatedly, in New York State proved that there are two distinct fungal species killing these hosts. One species proved to be new to science and is formally described here; the genomic data from both cranefly pathogens allowed them to be unambiguously assigned to the genus Zoophthora (whose species are known for their distinctive modes of forming their primary and secondary spores, none of which are known to be produced by these cranefly fungi). These findings prove that the molecular methods are now available to allow phylogenetically accurate reclassifications of many of the other Tarichium species (known only from their resting spores) into other genera among these fungi that are all much more accurately defined by their thin-walled conidial spore forms.

Technical Abstract: Molecular methods were used to determine the generic placement of two species of Entomophthorales known only from resting spores. Historically, these species would belong in the form-genus Tarichium, but this classification provides no information about phylogenetic relationships. Using DNA from resting spores, Zoophthora independentia, infecting Tipula (Lunatipula) submaculata in New York State, is now described as a new species and Tarichium porteri, described in 1942, which infects Tipula (Triplicitipula) colei in Tennessee, is transferred to the genus Zoophthora. We have shown that use of molecular methods can assist with determination of the phylogenetic relations of specimens within the form-genus Tarichium for an already described species and a new species for which only resting spores are available.