We present a phylogenetic revision of the Sticta filix morphodeme in New Zealand. This non-monophyletic group of early diverging clades in the genus Sticta is characterized by a stalked thallus with a green primary photobiont and the frequent formation of a dendriscocauloid cyanomorph. Traditionally, three species have been distinguished in New Zealand: S. filix (Sw.) Nyl., S. lacera (Hook. f. & Taylor) Müll. Arg. and S. latifrons A. Rich., with two cyanomorphs separated under the names Dendriscocaulon dendriothamnodes Dughi ex D. J. Galloway (traditionally associated with S. latifrons) and D. dendroides (Nyl.) R. Sant. ex H. Magn. (traditionally associated with S. filix). Sticta lacera was not included in the present study due to the lack of authentic material (all specimens originally identified under that name and sequenced clustered with S. filix); S. filix was confirmed as a distinct species whereas S. latifrons s. lat. was shown to represent two unrelated species, S. latifrons s. str. and the reinstated S. menziesii Hook. f. & Taylor. The cyanomorphs of S. filix and S. latifrons are not conspecific with the types of the names D. dendriothamnodes and D. dendroides, respectively; the D. dendriothamnodes cyanomorph belongs to the Australian taxon Sticta stipitata C. Knight ex F. Wilson, which is not present in New Zealand, whereas the D. dendroides cyanomorph corresponds to a previously unrecognized species with unknown chloromorph, recombined here as Sticta dendroides (Nyl.) Moncada, Lücking & de Lange. Thus, instead of three species (S. filix, S. lacera, S. latifrons) with their corresponding cyanomorphs, five species are now distinguished in this guild in New Zealand: S. dendroides (cyanomorph only), S. filix (chloro- and cyanomorph), S. lacera (chloromorph only), S. latifrons (chloro- and cyanomorph) and S. menziesii (chloro- and cyanomorph). A key is presented for identification of the chloromorphs and the dendriscocauloid cyanomorphs of all species. Semi-quantitative analysis suggests that species in this guild are good indicators of intact forest ecosystems in New Zealand and that the two newly recognized species, S. dendroides and S. menziesii, appear to perform particularly well in this respect. The use of lichens as bioindicators of environmental health is not yet established in New Zealand and so, based on our results, we make the case to develop this approach more thoroughly.
