Abstract Detail

Floristics & Taxonomy

McMurchie, Elizabeth [1], Peterson, Bryan [2], Leandro, Thales D. [1], Clark, Lynn [1].

New pieces of the Chusquea puzzle: A revision and recircumscription of Chusquea sect. Serpentes (Poaceae: Bambusoideae: Bambuseae).

The Neotropical woody bamboo genus Chusquea, which contains approximately 190 described species, is characteristic of montane forests, but can also be found in high elevation grasslands, tropical forests, and low elevation temperate forests. Most species of Chusquea, excepting the reed-like species that formerly belonged to the genus Neurolepis, have aerial rebranching and dimorphic complements of multiple buds at each node, both unusual features in bamboos. Chusquea poses taxonomic challenges due to an apparently ongoing radiation of species related to the uplift of the Andes and the formation of the Isthmus of Panama, complicated by a slow rate of evolution of chloroplast DNA, incomplete lineage sorting, hybridization, and a lack of collected specimens with viable DNA to test. This combination of factors has left much of the species-level determination of taxa to be based on morphology, which is additionally complicated by the long flowering cycles characteristic of woody bamboos. Specimens are often vegetatively or reproductively incomplete, and elucidating the morphological circumscription of a species is often like fitting together the pieces of a jigsaw puzzle. Chusquea sect. Serpentes, currently including six described species, is found throughout montane forests from Mexico south to the central Andes in Peru. Species of sect. Serpentes are climbing or scrambling in habit, with infravaginal branching, few subsidiary buds per complement (usually 2, but up to 12 in C. pohlii) in one constellate row, and foliage leaves that tend to be relatively wide and long compared to those of other members of Chusquea s.s. A review of available material of sect. Serpentes revealed at least two undescribed species, one known only vegetatively and the other known only in flower. The morphology and leaf anatomy of the two undescribed species are compared to C. serpens, to which they show the greatest similarity. One of the new species is native to Venezuelan montane forests in the states of Táchira and Mérida, and is distinguished from Chusquea serpens by having circular central buds, slightly asymmetrical, acute inner foliage leaf ligules, and up to 12 foliage leaves per complement. The other new species has been found only in the San Luís municipality of Antioquia, Colombia, in and around the Risaralda gorge, and differs from all other known species of sect. Serpentes by its broadly open panicles. We also recircumscribe Chusquea sect. Serpentes to remove the former member C. virgata, now placed as Incertae Sedis within Chusquea subg. Chusquea.

1 - Iowa State University, Department of Ecology, Evolution, and Organismal Biology, 2200 Osborn Drive, Ames, IA, 50011, USA
2 - University of Maine, School of Biology and Ecology, 5751 Murray Hall, Room 100, Orono, ME, 04469, USA


Presentation Type: Oral Paper
Session: FT1, Floristics & Taxonomy I
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 10:30 AM
Number: FT1FT003
Abstract ID:357
Candidate for Awards:None

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