Prodromus of a fern flora for Bolivia. XXIX. Aspleniaceae Author Kessler, Michael Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, CH- 8008 Zurich, Switzerland Author Smith, Alan R. University Herbarium, 1001 Valley Life Sciences Bldg. # 2465, University of California, Berkeley, CA 94720 - 2465 text Phytotaxa 2018 2018-03-16 344 3 259 280 http://dx.doi.org/10.11646/phytotaxa.344.3.6 journal article 10.11646/phytotaxa.344.3.6 1179-3163 Asplenium achalense Hieron., Bot. Jahrb. Syst. 22: 378. 1896 . Range:— Bolivia ( CH , CO, LP, SC, TA) to northwestern Argentina . Ecology:— Locally fairly common; epiphytic, terrestrial, and saxicolous in semihumid forests, especially with Weinmannia L. and Podocarpus L.Her. ex Pers. ; 1050–3300 m . Notes:— The distinctions between A. achalense and A. serra , as well as between related species ( A. incurvatum , A. mosetenense , and A. tunquiniense ), remain poorly understood ( Kessler & Smith 2006 ). In addition to the characters presented in the key, A. achalense tends to have blades with more strongly reduced distal pinnae (distal pinnae <50% as long as longest pinnae vs .>50% in A. serra ) and more strongly biserrate pinna margins ( vs . margins more finely and regularly serrulate). Juvenile plants of A. achalense have strongly dissected leaves that are often up to 1-pinnate-pinnatisect in earliest leaves and become gradually less dissected as plants grow. In contrast, the earliest leaves of A. serra are typically undivided, resembling the terminal pinna of the mature plants, and only with age and size do the leaves attain additional lateral pinnae. Distinctions between A. achalense and A. serra are also supported by a molecular and morphometric study ( Jonas 2011 ). However, three other species recognized here and by Kessler & Smith (2006 ; A. incurvatum , A. mosetenense , and A. tunquiniense ) were found by Jonas (2011) to nest within A. achalense , using molecular and morphometric data, and can be recognized only by the rhizome scale characters used in our key. To complicate matters, “ A. serra ”, as described in some Argentinean floras ( de la Sota 1977 , Ganem et al . 2007 ), is not identical to A. serra as recognized here and actually represents a variant of A. achalense as delimited by Kessler & Smith (2006) and here; it is possible that true A. serra does not occur in northeastern Argentina ( Jonas 2011 ). Asplenium achalense may thus best be interpreted as a species complex; pending further research we choose to maintain five separate species, in order to call attention to the taxonomic issues.