Using ascospore size as a first tool to identify verrucoid Pertusaria species DC. species from Aotearoa / New Zealand

Anthony E. Aldridge¹, Jennifer M. Bannister²

Affiliations/ Address:
1 20 Genia Drive, Wakefield, Tasman 7025, New Zealand.
2 Botany Department, Otago University, Dunedin 9016, New Zealand.
Corresponding author: tony@southnet.co.nz

Received: 14 August 2025 | Accepted: 15 August 2025 | Published: 21 October 2025
Associate Editor: Peter de Lange
https://doi.org/10.34074/pibdiv.003108

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Abstract
The widespread crustose lichen genus Pertusaria DC. (Pertusariaceae) is present throughout Aotearoa / New Zealand. These Pertusaria species exhibit many variable thalline features in colour and shape. The chemicals present are helpful in the identification of Pertusaria species, but the very detailed results obtained by high-performance liquid chromatography (HPLC) now render existing descriptions difficult to use. The average spore size, substrate and number of spores per ascus, however, remain stable features amenable to statistical methods for discriminating among species. In this study, the length and width of 563 ascospores of 23 species of verrucoid Pertusaria found in Aotearoa / New Zealand were measured. Fresh ascospore preparations were used and only mature ascospores were measured. All measurements were made by one person (JMB). Published ascospore measurements were later added so that the results would include information about all Aotearoa / New Zealand verrucoid species of Pertusaria.
Statistical outline analysis showed that mature ascospores were consistently elliptical in 2D (R² > 99%), confirming that length and width are sufficient to completely describe ascospore shape. Bivariate analysis highlighted which species were significantly different from each other. This novel, yet simple visual display of mean ascospore length and width, together with the type of substrate and the number of ascus spores, is proposed as an effective means of identifying verrucoid species of Pertusaria.

Cite as
Aldridge, A. E., Bannister, J. M. (2025). Using ascospore size as a first tool to identify verrucoid Pertusaria DC. species from Aotearoa / New Zealand. Perspectives in Biodiversity 3(1): 83–98. https://doi.org/10.34074/pibdiv.003108