Donadıo et al. 2015 (Article) Tillandsia

Phylogenetic relationships within Tillandsia subgenus Diaphoranthema (Bromeliaceae, Tillandsioideae) based on a comprehensive morphological dataset

Author(s):—S. Donadío, R. Pozner & L.M. Giussani

Publication:—Plant Systematics and Evolution 301: 387–410. (2015) — DOI

Abstract:—Tillandsia
subgenus
Diaphoranthema

landsioideae, Bromeliaceae) includes 29 epiphytic species
distributed widely from southern North America to central
Argentina and Chile. The species of
Diaphoranthema
are
characterized by few small flowers, and most species are
differentiated by phyllotaxy, leaf shape, flower number,
and by the morphology and number of bracts. In addition to
the highly variable vegetative characters, most species of
subgenus
Diaphoranthema
possesses polyembryonic seeds
(rare in Bromeliaceae) and an autogamous breeding system
with a few number of species having cleistogamous flow-
ers. In order to clarify relationships within
Diaphoranthe-
ma
and to understand the evolution of polyembryony, the
breeding system, and diagnostic characters, a cladistic
analysis of all known species using 85 morphological
characters was conducted. Phylogenetic results suggest that
Diaphoranthema
is monophyletic if some species from the
closely related subgenus
Phytarrhiza
are included. These
two subgenera can only be distinguished from each other
by the shape and size of their petals. A complete sampling
of
Phytarrhiza
is still needed to test these hypotheses. None
of the six informal groups as previously recognized are
monophyletic. Vegetative characters such as phyllotaxy
and the shape, length, and width of leaves were the most
useful for distinguishing four major clades within
Di-
aphoranthema
. Flower number, scape development, exo-
carp and endocarp fusion at fruit ripening, and absence of
endosperm in mature seeds were also used to distinguish
some clades. Evolutionary trends favour a distichous
phyllotaxy, linear shape leaf blades, and a reduction in
flower number and bracts per inflorescence. In addition,
capsules with disaggregating exocarp and endocarp at
ripening, and polyembryonic seeds are also derived states
within subgenus
Diaphoranthema
.

Keywords:—Phylogeny, Tillandsia, Diaphoranthema, Morphology

Taxonomy:—Tillandsia crocata Placed in Tillandsia subgen. Diaphoranthema (p.390).