Columnea bivalvis (Gesneriaceae) a new species from the eastern slopes of the Ecuadorian Andes

Abstract

Recent field expeditions to the eastern slopes of the Ecuadorian Andes and revisionary work on Columnea (Gesneriaceae) section Collandra have resulted in the discovery of a new plant species. The new species, Columnea bivalvis, is distinguished by the presence of two pendent clasping bracts that enclose a single axillary flower.

Full text

J. Bot. Res. Inst. Texas 5(1): 75 – 79. 2011
COLUMNEA BIVALVIS (GESNERIACEAE), A NEW SPECIES
FROM THE EASTERN SLOPES OF THE ECUADORIAN ANDES
Marisol Amaya-Márquez* John L. Clark
Instituto de Ciencias Naturales Department of Biological Sciences
Universidad Nacional de Colombia Box 870345
Apartado 7495, Bogotá, COLOMBIA The University of Alabama
mamayam@unal.edu.co Tuscaloosa, Alabama 35487, U.S.A.
*Corresponding author
abstraCt
Recent f ield exped itions to the e astern slope s of the Ecuador ian Andes a nd revisio nary work on Columnea (Gesneri aceae) section C ollandra
have resulted in t he discovery of a new plant species. The new species, Columnea bivalvis, is dist inguished by the presence of t wo
pendent clasping bracts that enclose a single axillary flower.
resumen
Expediciones recientes a las estribaciones orientales de los A ndes Ecuatorianos, y el trabajo de revisión de la sección Collandra del gé-
nero Columnea (Gesneriaceae) perm itieron el descubrimiento de una nueva especie de planta. La nueva es pecie, Columnea bivalv is, se
distingue por tener dos brácteas colgantes que se tocan por su s márgene s encerrando una única flor axil ar.
key worDs: Collandra, Columnea, Gesneriaceae, Ecuador, Taxonomy, Flora of Ecuador
introDuCtion
The genus Columnea belongs to the New World subfamily Gesnerioideae. It is the most diverse genus in
the subfamily with over 200 species (Skog & Boggan 2006; Weber 2004; Burtt &Wiehler 1995). The sub-
division of Columnea sensu lato into sections or into segregate genera has caused much controversy and
taxonomic confusion (Kvist & Skog 1993; Wiehler 1973, 1983). We recognize the classification based on
recent phylogenetic hypotheses that strongly support the monophyly of Columnea (Smith 1994; Smith &
Sytsma 1994; Clark et al. 2006) and non-monophyly for segregate genera. Thus, the sectional classification
outlined in Kvist and Skog (1993) is more desirable as an informal classification until segregate clades can
be evaluated phylogenetically.
The new specie s described here belongs to Collandra, the most diverse section in Columnea. The following
characters are useful for recognizing the species within this section: dorsiventral shoots with anisophyllous
subsessile leaves and ovoid (non-globose) berries. In this paper we describe a new species of Columnea that
is known from two populations between 1800 and 2350 m from the eastern slopes of the Ecuadorian Andes.
taxonomiC treatment
Columnea bivalvis J.L. Clark & M. Amaya, sp. nov. (Figs. 1 & 2). type: ECUADOR. tungurahua. Cantón Baños: par-
roquia Río Verde, sector Machay, forested trail (from Baños-Puyo road) towards Cascada de San Miguel via San Augustin, 1°23'5"
S, 78°16'50"W, 1800–2200 m, 23 Dec 2000, J.L. Clark, E. Narvaez & J. Vargas 5693 (holotype: US; isotypes: COL, MO, NY, QCA,
QCNE, SEL).
Differ t a ceteris Columnei s praes entia unius floris ax illaris inclusi in bin is bracteis amplectentibus by t he presence of a single axillary
flower enclosed by a pair of pendent clasping bracts.
Epiphytic vine, suffrutescent, often branched; stem terete, 0.3– 0.8 cm, reddish villous (trichomes 7–10
celled), internodes 1–4 cm long. Leaves opposite, strongly anisophyllous in a pair, chartaceous; larger leaf
with petioles 0.3–0.9 cm long, densely reddish villous; blade asymmetrical, narrow oblong to oblanceolate,
9.5–20 × 2.2–4.2 cm, base oblique, apex acumin ate, margin dentate; adaxi ally green, golden vi llous (trichomes
5–7 celled) and with sparsely distributed white unicellular setulose hairs, veins not prominent; abaxially

76 Journal of the Botanical Research Institute of Texas 5(1)
Fig. 1. Columnea bivalvis. A. Habit and inflorescence. B. Enlargment of larger leaf margin. C. Calyx and gynoecium. D. Corolla and androecium. E. Fruit.
F. Seed.

Amaya and Clark, Columnea bivalvis, a new species from Ecuador 77
Fig. 2. Columnea bivalvis. A. One of the paired bracts removed to show uniformly yellow tubular corolla. B. Dorsiventral shoot showing pendent bracts
(photos by J.L. Clark; from the live plant from which the holotype was collected, J.L. Clark, E. Narvaez & J. Vargas 5693).

78 Journal of the Botanical Research Institute of Texas 5(1)
green with red venation, villous (trichomes 5–7 celled), 8–10 pairs of lateral veins; smaller leaf sessile, blade
asymmetrical, oblong, 1.5–2 × 0.3–0.5 cm, base oblique, apex attenuate, margin dentate, adaxially green,
reddish villous (trichomes 7 celled), abaxially green, reddish villous (trichomes 7 celled). Inflorescence
epedunculate with 1 flower per node, larger bracts persistent and paired, green with red margins, outer
surface reddish villous, asymmetrical, broadly ovate, 4–4.7 × 2.5–3 cm, bracteoles 2–4, unequal in size,
narrowly ovate to lanceolate, 1.2–2.5 × 0.2–1 cm, pedicel 0.2–0.4 cm long, densely villous (trichomes 4–5
celled). Calyx pale green; lobes 5, nearly free joined only at the base by 1 mm of their length; narrow oblong,
1.5 × 0.3 cm, margin dentate with three glandular teeth on each side, outside densely villous (trichomes
5–7 celled), inside glabrous. Corolla uniformly yellow, tubular, 3.7–4.5 × 0.8–1 cm, basally gibbous and
slightly oblique in the calyx, gibbosity 0.4 × 0.5 cm constricted apically 0.3 cm, 0.8–1 cm at the widest
part of the tube and constricted again at the limb to 0.7 cm; limb nearly actinomorphic, slightly ampliate
in mid region, lobes rounded, subequal 0.3 × 0.3 cm, outside apically sericeous, glabrescent toward the
base (trichomes 8–12 celled), inside glabrous. Androecium of 4 stamens, filaments 3.2 cm long, glabrous,
basally connate for 0.5 cm; anthers oblong 2.0 × 1.3 mm, connective rectangular, 1.8 × 1.2 mm. Nectary a
single dorsal trilobed gland. Gynoecium with the ovary ovoid, 0.7 × 0.3 cm, densely sericeous; style 2.5–3
cm long, laminar with glandular trichomes; stigma bilobed. Fruit an ovoid berry, 1.5 × 0.8 cm. Seeds light
brown 1.8 × 0.5 mm, elliptic, and longitudinally striate.
Distribution and habitat.—Columnea bivalvis is only known from two localities in the wet Andean cloud
forests in eastern Ecuador between 1800 and 2350 m.
Phenology.—Flowers and fruits collected in April and December.
Columnea bivalvis is unique among the species of Columnea by having a pair of large pendent bracts that
enclose a single axillary flower (Figs. 1–2). The yellow tubular flowers are almost completely enclosed by the
bracts with only the throat extending beyond the bract margins. The bracts in C. bivalvis are superficially
similar to the Drymonia hoppii and D. affinis. Although large bracts are common in many Columnea species
and especially those belonging to the section Collandra, no species is known to have large pendent bracts
and dorsiventral shoots.
Columnea bivalvis is similar to C . medicinalis, C. albiflora, and C.eubracteata. The latter three species differ
by the presence of congested bracts compared to a pair of large pendent bracts (i.e., non-congested) in C.
bivalvis, and by the prominent bilabiate corolla limbs compared to a nearly actinomorphic corolla limb in
C. bivalvis.
Etymology.—The new species is named in reference to the marine and freshwater mollusca belonging to
the class Bivalvia because of the resemblance to the two large rounded bracts that enclose a single axillary
flower.
paraty pe: ECUADOR. Napo: Km 40 from El Carmelo on road towards La Bonit a, near 5 km below La Alegría, 0°35'N, 77°30'W, 2350
m, 8 Apr 1979, B. Lojtnant et al. 11930 (NY).
aCknowleDgments
We thank the Herbario Nacional Colombia (COL), the Smithsonian Institution’s National Museum of Natural
History – Department of Botany (US), and the Herbario Nacional del Ecuador (QCNE) for access to their
collections. We thank Laurence E. Skog (US) for his willingness to collaborate on the revision of Collandra.
Funding for M AM came from The Gesneriad Society’s Elv in McDonald Research Endowment Fund. Funding
for JLC came from the National Science Foundation (DEB-0841958 & DEB-0949169). We also thank Juan
Carlos Pinzón for the illustration and Pedro Ortiz for help in selecting an appropriate specific epithet and
the Latin description. We thank John R. Clark and Harry Luther for providing helpful comments to an early
version of the manuscript.
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