Abstract Detail

Systematics

Ballard Jr, Harvey E [1], Gatt, Kyle P [2], Zumwalde, Bethany A [3].

Reinventing taxonomy for the Acaulescent Blue violets (Viola subsect. Boreali-Americanae).

The Acaulescent Blue violets (Viola subsection Boreali-Americanae) are the most taxonomically challenging and diverse group of violets in North America and one of the most complex in the world. Frequent apparently fertile hybrids, bewildering phenotypic variation in many taxa, and different emphases on morphological traits have produced several wildly divergent, seemingly irreconcilable taxonomic treatments over the last 120 years. Our research group has embarked on a different taxonomic approach in which we use the Unified Species Concept as an objective filter on diverse lines of evidence to distinguish sets of populations as evolutionary species and segregate these from putative de novo hybrids. Our investigations since 2012 have relied heavily on intensive field surveys and local herbarium collections in the central and southern Appalachian Mountain and Atlantic Coastal Plain regions as a beginning point. We have coupled Ezra Brainerd’s invaluable common garden approach and emphases on cleistogamous capsule and seed morphology with Nir Gil-ad’s exacting circumscriptions and scanning electron microscopy, augmenting these with ecological observations and statistical analyses of data sets. Our evidence includes numerous macromorphological traits across the plant body; microscopic features on lateral petal trichomes and seed coats; ecological niche variables; mature seed output of chasmogamous and cleistogamous capsules; and local and regional geographic distribution. Highly uniform macromorphological features of cleistogamous capsules and seeds, and micromorphological traits of seeds revealed by SEM, have demonstrated remarkable uniformity within taxa and dramatic divergence between taxa. Fruiting traits have been overwhelmingly effective in confirming distinctness of species where foliage or chasmogamous flower traits have proven less useful or informative. Our preliminary results unequivocally maintain all species of Acaulescent Blue violets recognized by Brainerd and his contemporaries early in the last century, and furthermore reveal nine undescribed species thus far. We have circumstantial evidence to suggest another 10 taxa may also be distinct, but these require much further investigation. At present we anticipate recognizing 40 acaulescent blue violet species, where treatments proposed in the last 75 years have accepted less than half that number. Generally, more species, and more narrowly delineated endemic species, must be recognized in the Boreali-Americanae lineage. Some of these are not represented, or not represented adequately, in larger herbaria, and a few have been detected for the first time only through our intensive field studies, highlighting the critical importance of local and regional herbarium collections and field-centered taxonomic investigations to document biological diversity in a taxonomically perplexing group.

1 - Ohio University, ENVIR & PLANT BIOLOGY-PORTER H, 315 Porter Hall, Athens, OH, 45701-2979, USA
2 - Ohio University, Biological Sciences, Athens, OH, 45701, USA
3 - Desert Botanical Garden, 1201 N. Galvin Parkway, Phoenix, AZ, 85008, USA

Keywords:
Viola
taxonomy
Unified Species Concept
species boundaries.

Presentation Type: Oral Paper
Session: 41, Basal Rosids & Rosids I
Location: 101/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 10:45 AM
Number: 41011
Abstract ID:235
Candidate for Awards:None