A Multivariate Study of Morphological Characters for Echinocactus horizonthalonius and E. texensis (Cactaceae) and Description of a New Subspecies, E. horizonthalonius subsp. australis

A study was conducted to ascertain the taxonomic validity of endangered taxon Echinocactus horizonthalonius var. nicholii and whether there may be other groups populations worthy subspecies status within range species. To test hypothesis that individuals E. are morphologically distinct from those typical variety, a multivariate analysis done compare degree morphological variation or phenotypic plasticity stem characters among throughout its known range. Populations texensis were sampled for outgroup comparison. Discriminant function (DFA) assigning by population showed loose groupings geographically correlated populations. The DFA regions potential subspecific taxa indicated high percentages correct classification grouped into Chihuahuan Desert, Sonoran Central Mexican Plateau regions. Taxonomically, these correspond subsp. (Chihuahuan Desert), (Sonoran unnamed (Central Plateau). Because entities with regional distributions, they placed here under subspecies, including newly described taxon, australis. no type could located, neotype is designated.