New species of Tulasnella associated with Australian terrestrial orchids in the subtribes Megastylidinae and Thelymitrinae

ABSTRACT

Tulasnella (Tulasnellaceae) is a genus of fungus that can form mycorrhizal associations with orchids (Orchidaceae). Here we used molecular phylogenetic analyses and morphological characteristics of pure cultures across four different media to support the description of five new Tulasnella species associated with commonly occurring and endangered Australian orchids. Tulasnella nerrigaensis associates with Calochilus; T. subasymmetrica and T. kiataensis with Thelymitra; and T. korungensis and T. multinucleata with Pyrorchis and Rimacola respectively. The newly described species were primarily delimited by analyses of five loci: nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS), C14436 (adenosine triphosphate [ATP] synthase), C4102 (glutamate synthase), C3304 (ATP helicase), and mt large subunit 16S rDNA (mtLSU). Tulasnella subasymmetrica is introduced for some isolates previously identified as T. asymmetrica, and this latter species is characterized from multilocus sequencing of a new isolate that matches ITS sequences from the ex-type culture. Morphological differences between the new species are slight. Tulasnella multinucleata has 6–12 nuclei per hyphal compartment which is the first instance of multinucleate rather than binucleate or trinucleate hyphal compartments in Tulasnella. The formal description of these species of Tulasnella will aid in future evolutionary and ecological studies of orchid-fungal interactions.

KEYWORDS:

• Binucleate
• Cantharellales
• morphology
• multinucleate
• orchid mycorrhizal fungi
• taxonomy
• Tulasnellaceae
• 5 new taxa

ACKNOWLEDGMENTS

We thank Ryan Phillips, Rod Peakall, Alyssa Weinstein, Mary Argall, and Mark Clements for assisting with field work and sampling; Tobias Hayashi and Sharyn Wragg for assisting with photography of cultures; Carlos Pavón Vázquez for helping with phylogenetic analyses; Farid Rahimi for microscopy assistance; Leon Smith and Richard Dimon for initial laboratory work with culture collections; Jordan Bailey for information about collections at DAR; and John Dearnaley for providing an isolate of T. asymmetrica. We also thank Brandon Matheny, Alfredo Justo, and two anonymous reviewers for comments on an earlier version of the manuscript.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

ETHICAL APPROVAL STATEMENT

Permissions were obtained from the state authorities to collect all plant materials in this study: New South Wales National Parks & Wildlife Service (permit number SL100294), Western Australia Department of Parks and Wildlife (permit number SW017980), and Department of Environment, Land, Water & Planning Victoria (permit number 10008918).

SUPPLEMENTARY MATERIAL

Supplemental data for this article can be accessed on the publisher’s Web site.

Additional information

Funding

This work was supported by the Australian Orchid Foundation to Noushka Reiter (grant no. 273/2010) and Arild Arifin (grant no. 324/2017). Noushka Reiter was also supported by National Landcare Programme funding through the Wimmera Catchment Management Authority.