Abstract Detail

Systematics Section/ASPT

STEFANOVIC, SASA [1], Costea, Mihai [2].

Species delimitation and phylogenetic relationships in the Cuscuta tinctoria species complex (subgenus Grammica; Convolvulaceae).

Broad molecular phylogenetic analyses of parasitic genus Cuscuta identified the C. tinctoria complex as one of the 15 major clades in the subgenus Grammica.  This group, the second largest of subg. Grammica, includes 14 species that are centered in Mexico and adjacent regions, but also two species that are found in Australia, presumably as a result of long-distance dispersal.  Flowers, pollen, and stigmas are among the largest in Cuscuta, with plants being xenogamous or facultatively xenogamous.  In this clade, the convergent evolution of morphological traits, especially those associated with the calyx and gynoecium/capsule, has obscured the identity of some species and has hindered previous efforts to determine their limits.  We have examined specimens from over 100 herbaria worldwide, and we have conducted extensive fieldwork in Mexico and the U.S.A.  Basic morphology, scanning electron microscopy and sequence data from the nuclear internal transcribed spacer (ITS) and the plastid trnL-F region were used to reconstruct the phylogeny, gain a better understanding of the evolutionary history, and determine species boundaries.  Overall, species were grouped in five subclades.  Based on their morphological and molecular similarly, C. tinctoria, C. aurea, and C. floribunda are best treated as a single species, with the latter two taxa being retained as varieties of the former.  Our results also show that in their currently accepted delimitation C. rugosiceps and C. tinctoria are polyphyletic, the former including one new species, C. volcanica, and the latter two new species, C. timida and C. tolteca.  In addition, three other new species are described: C. iguanella and C. insolita, both with multicellular protuberances on the calyx and/or corolla lobes, and C. montana, with broader than long calyx lobes.

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1 - UNIVERSITY OF TORONTO Mississauga, Department Of Botany, 3359 MISSISSAUGA RD, MISSISSAUGA, ON, L5L 1C6, Canada
2 - Wilfrid Laurier University, Biology, 75 University Avenue West, Waterloo, Ontario, N/A, N2L3C5, Canada

Keywords:
Cuscuta
ITS phylogeny
trnLF phylogeny
parasitic plants
Convolvulaceae.

Presentation Type: Oral Paper:Papers for Sections
Session: 33
Location: River Fork/Grove
Date: Wednesday, July 30th, 2014
Time: 9:00 AM
Number: 33005
Abstract ID:129
Candidate for Awards:None