Abstract Detail

Systematics

Adler, Ava [1], Douglas, Norman [2], Flores Olvera, Hilda [3], Ochoterena, Helga [4], Moore, Michael [1].

Unfolding Potential New Taxa of Paperflowers (Psilostrophe) on Gypsum.

Psilostrophe (Asteraceae: Helenieae), commonly known as paperflower, is a southwestern North American genus of five species of perennial herbs. Two closely related species, P. tagetina and P. gnaphalodes, inhabit much of New Mexico, Texas, and northeastern Mexico, and present a confusing range of morphological variation. These two species grow on a variety of calcareous substrates, but have a high affinity for gypsum (calcium sulfate)-derived soils, often being relatively common on such soils. Recent fieldwork has led to the discovery of two sets of populations, one on the Castile Formation of gypsum in west Texas & southeastern New Mexico, and the other on the Acatita Formation of western Coahuila, each of which is morphologically distinctive from other species of Psilostrophe. The former is distinguished by having a very small habit; in contrast, the latter is very large with large, spathulate basal leaves. To test whether these two population groups might represent two new taxa, we reconstructed the evolutionary relationships within the genus by generating DNA sequence data of over 100 Psilostrophe specimens collected from herbaria and the field, with particular emphasis on including numerous populations of P. tagetina and P. gnaphalodes from across their ranges. We sequenced two plastid spacer regions, ndhF/rpl32 and rpl32/trnL, as well as the nuclear ITS region for all samples. The sequence data revealed that these two species form a single, well-supported clade. However, neither species was monophyletic, and sequence divergence and resolution was low, perhaps reflecting extensive potential hybridization and/or incomplete lineage sorting. Both the Castile Formation and Acatita Formation gypsum populations each possessed unique plastid haplotypes, but shared identical haplotypes with other populations of Psilostrophe in ITS. In particular, the Acatita Formation populations shared an ITS haplotype with populations of P. gnaphalodes var. mexicana. Our data do not clearly resolve the taxon status of these gypsum populations, but if they are recognized, it may be best to recognize them at the varietal level.

Related Links:
Evolution of Chihuahuan Desert gypsum endemic plants

1 - Oberlin College, Department Of Biology, 119 Woodland St., Science Center K111, Oberlin, OH, 44074, United States
2 - University Of Florida, Biology, PO Box 118525, Gainesville, FL, 32611, United States
3 - Instituto De Biolog�a, UNAM, Depto Bot�nica, Apdo.Postal 70-367, Coyoacan, Mexico, DF, 04510, Mexico
4 - Instituto De Biología, UNAM, Botanica, Depto Botánica-Apdo.Postal 70-367, Coyoacan, Mexico DF, 04510, Mexico

Keywords:
gypsum
Mexico
New Mexico
Texas
Coahuila
Asteraceae
phylogeny.

Presentation Type: Poster
Session: P, Systematics Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PSY003
Abstract ID:196
Candidate for Awards:None