Abstract Detail

Systematics

Wilkinson, Joshua [1], Alford, Mac [2].

Reassessment of Species Boundaries and Phylogenetic Relationships in the Desmodium ciliare complex (Fabaceae) Using Morphological and DNA Data.

Desmodium (Beggar's ticks/lice, Tick-trefoils) is a genus of approximately 280 to 300 species within Fabaceae (Subfamily Papilionoideae, Tribe Desmodieae). A largely weedy group in temperate North America, beggar's ticks hold true to their name by epizoochorous dispersal via hooked hairs on the segmented loments that attach to vertebrate fur and human clothing. Within the Southeastern United States, the Desmodium ciliare group is one of two Desmodium species complexes that have been historically difficult, with much argument about the limits of species and the role of hybridization. There are three commonly recognized species within the D. ciliare group, D. ciliare (Muhl. ex Willd.) DC., Desmodium marilandicum (L.) DC., and D. obtusum (Muhl. ex Willd.) DC., with two supposed hybrids in addition to the three main species: D. ciliare × Desmodium strictum (Pursh) DC. and D. ciliare × Desmodium paniculatum (L.) DC. The three putative species in this complex differ morphologically by terminal leaflet length:width ratio, amount of pubescence on stems (and leaves), whether uncinate pubescent (with hooked hairs), pilose (sometimes with uncinate pubescence), or glabrate, and petiole length. To test the species boundaries, focused principally on material collected in Mississippi where all of the three putative species occur, principal component analysis (PCA) of morphological characteristics and analyses of both plastid and nuclear DNA were utilized. DNA data currently includes nuclear ITS and Histone H3-D and plastid trnL and trnH–psbA, with analysis by both parsimony and Bayesian methodologies, but other regions are being investigated for variation. Preliminary data has shown 10 sites of single nucleotide polymorphisms between members of the complex. This study aims to test the species boundaries in the Desmodium ciliare complex, to resolve the relationships between the species, and to resolve the relationships of the D. ciliare complex among other Desmodium found in Mississippi.

1 - University of Southern Mississippi, Biological, Earth, and Environmental Sciences, 118 College Dr. #5018, Hattiesburg, MS, 39406, USA
2 - University Of Southern Mississippi, School Of Biological, Environmental, And Earth Sciences, 118 College Drive #5018, TEC 103, Hattiesburg, MS, 39406, United States

Keywords:
Taxonomy
Desmodium
Papilionoideae  
Systematics.

Presentation Type: Poster
Session: P3, Systematics Posters
Location: Virtual/Virtual
Date: Wednesday, July 21st, 2021
Time: 5:00 PM(EDT)
Number: P3SY008
Abstract ID:671
Candidate for Awards:None