Myoxanthus ortizianus (Orchidaceae), a new species from southern Colombia

Abstract

With over 3000 species, Colombian orchid flora represents one of the richest in the World. The neotropical subtribe Pleurothallidinae is the most diverse, but it is still a poorly recognized Orchidaceae group and numerous new discoveries within national representatives are described every year. An examination of material collected recently in the Colombian department of Putumayo revealed the existence of a new species of Myoxanthus, named M. ortizianus, which is described, illustrated and placed within an identification key for national species of the nominal section of the subgenus Myoxanthus.

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©Adam Mickiewicz University in Poznań (Poland), Department of Plant Taxonomy. All rights reserved.
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VARIABILITY, TAXONOMY AND PHYLOGENY
Myoxanthus ortizianus (Orchidaceae), a new species
from southern Colombia
Marta Kolanowska* & Dariusz L. Szlachetko
Department of Plant Taxonomy and Nature Conservation, The University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland
* corresponding author (e-mail: martakolanowska@wp.pl)
Abstract: With over 3000 species, Colombian orchid ora represents one of the richest in the World. The neotropical subtribe
Pleurothallidinae is the most diverse, but it is still a poorly recognized Orchidaceae group and numerous new discoveries within
national representatives are described every year. An examination of material collected recently in the Colombian department
of Putumayo revealed the existence of a new species of Myoxanthus, named M. ortizianus, which is described, illustrated and
placed within an identication key for national species of the nominal section of the subgenus Myoxanthus.
Key words: Colombia, Myoxanthus, new species, Pleurothallidinae, Putumayo, taxonomy, Valle de Sibundoy
DOI 10.2478/biorc-2014-0025 Submitted 18.12.2013, Accepted 29.12.2014
Biodiv. Res. Conserv. 36: 7-10, 2014
1. Introduction
The genus Myoxanthus was proposed by Poeppig
& Endlicher (1835) to identify a newly collected spe-
cies characterized by a well-developed ramicaul with
a fascicle of single owers arising simultaneously at
its apex and distinguished by basally connate lateral
sepals, an oblong-ligulate lip and an apically irregular
gynostemium with a pair of teeth in the apical part and
a concave column-foot. The new genus was synony-
mized with Pleurothallis by Lindley only a year later
(Lindley 1836) and, in 1859, the same author placed all
known Myoxanthus species in the section Aggregatae
of Pleurothallis (Lindley 1859). At this time, just a few
species of the genus had been recognized and over the
next 120 years it enlarged to almost 40 taxa. In 1982,
Myoxanthus was re-established (Luer 1982), supported
by vegetative anatomy (Pridgeon 1982; Pridgeon & Stern
1982).
In 1992, Luer divided the genus into three subgenera
based on an inorescence arrangement and the structu-
re of the sheaths enclosing the ramicaul. The same
author established additional three sections within the
largest subgenus – Myoxanthus. The molecular studies
of Pridgeon et al. (2001), together with the results of
detailed studies on the leaf anatomy resulted in the
unication of the subgenera Satyria and Silenia into
a new genus Echinella Pridgeon & M. W. Chase.
As currently recognized, Myoxanthus includes
plants distinguished by the presence of coralloid raph-
ide clusters in the foliar epidermis, scruffy sheaths
and few-owered inorescence arising from near the
ramicaul apex. The sepals are usually pubescent, the
petals are often thickened towards the apex and the thick
lip is hinged on the column-foot. The gynostemium is
variously toothed or winged apically and the anther cap
is cellular-glandular (Luer 1992; Pridgeon et al. 2001).
The geographical range of the genus is restricted
to the Neotropics, from Mexico to southern Brazil. In
Colombian ora, 14 species have been registered thus
far. Most of them occur above 1000 m a.s.l. Only three
species, Myoxanthus afnis (Lindl.) Luer, M. mono-
phyllus Poepp. & Endl and M. trachychlamys (Schltr.)
Luer, were reported from the warm lowland regions of
the country (Ortiz Valdivieso & Uribe Vélez 2007).
During the course of the study on the Colombian
orchids, a distinctive species of the section Myoxanthus
subgenus Myoxanthus was found and it is described here
as new.
2. Material and methods
The comparative research was conducted in the
herbaria COL, HPUJ, K, MEDEL, UGDA and W. Dried
Myoxanthus specimens as well as owers preserved
in liquid were examined according to the standard
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8
procedures. The photographs provided on the herbarium
sheets were carefully studied. First, the shape and size of
the leaf blade was studied. The oral segments as well
as the form of ovary and oral bracts were examined
after softening owers in boiling water. Comparison of
the studied material with the designated type specimens
and protologues assured the correctness of identica-
tions. The eld studies have been conducted during
expeditions to Colombian department of Putumayo in
2012 and 2013.
3. Description and taxonomic notes
Myoxanthus ortizianus Kolan. & Szlach., sp. nov.
(Figs. 1-2)
Species similar in ower morphology to Myoxanthus
priapus Luer, distinguished by the presence of the
scruffy sheaths of the ramicaul, the long pedicels and
ovaries, the simultaneously produced flowers with
oblong-ovate lip and the obliquely ovate lateral sepals.
Type: COLOMBIA, Putumayo. Valle del Sibundoy.
Vereda San José del Chunga. Alt. ca 2200 m. 19 Jan
2007. Flowered in cultivation Mar 2007. ex cult. R.
Medina T. 466 (holotype: HPUJ!, MEDEL – photos,
UGDA! – drawing).
Etymology. Dedicated to Pedro Ortiz Valdivieso
(1926-2012), an eminent Colombian orchidologist.
Description: Epiphytic, caespitose plants. Roots
liform. Ramicaul stout, erect, up to 45 cm long, en-
closed by a few tubular sheaths 4.5-5 cm long, basal
Fig. 1. Myoxanthus ortizianus – habitat and dissected ower
Explanations: A – habit, ramicaul and leaf apex details, scale bar = 10 cm; B – dorsal sepal; C – petal; D – lateral sepals; E – lip; F – lip, gynostemium and
petal, scale bars = 5 mm. Drawn from the holotype
Myoxanthus ortizianus (Orchidaceae), a new species from southern Colombia
Marta Kolanowska & Dariusz L. Szlachetko
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9
part sparsely covered with black hairs. Leaf erect, co-
riaceous, blade 15-20 cm long, about 2 cm wide, linear-
lanceolate, acute, base subpetiolate. Inorescence a
fascicle of 2-5 owers; enclosed by thin sheaths 15 mm
long. Flowers produced simultaneously, brownish-red,
petals yellow with reddish veins, lip maroon, all sepals
densely pubescent externally, lateral sepals pubescent
also on the inner margins. Floral bracts 7-9 mm long.
Ovary ca 6 mm long, arched, pubescent, pedicel up to
1.5 cm long, glabrous. Dorsal sepal 11 mm long, 5 mm
wide, concave, narrowly ovate, subobtuse, 5-veined.
Lateral sepals 8 mm long, 5 mm wide, obliquely ovate,
acute, connate for 3 mm, 3-veined. Petals 6 mm long,
4.4 mm wide, ovate, abruptly contracted into an ob-
tuse tails 5 mm long, 3-veined. Lip 3.2 mm long, 1.8
mm wide, minutely clawed, oblong-ovate, thick, base
subtruncate, hinged on the column-foot; basal part with
rounded sides, the apical part oblong, obtuse; almost
the whole disc covered with a thick, verrucose callus.
Gynostemium about 3.5 mm long, alate, with a concave
column-foot 3 mm long.
Distribution, habitat and ecology: Thus far, it is
known only from the Colombian Andes, the Sibundoy
valley in the Department of Putumayo, where it was
found growing epiphytically in the very humid montane
forest, at about 2200 m of elevation. In its natural habitat
it owers in January.
Taxon o m i c note s : Based on the caespitose habit
of the new species, the scruffy sheaths of the ramicaul
and owers produced laterally, simultaneously from
near the apex of the ramicaul, this species belongs to
the nominal section of the subgenus Myoxanthus. The
owers of M. ortizianus slightly resemble those of M.
ceratothallis (Rchb. f.) Luer, which is widely distributed
through South America, as well as M. priapus Luer,
which is known from Ecuador and Peru. Both of these
species belong to the section Antenella. M. ortizianus is
easily separable from these species by the oblong-ovate
lip, with its lower part characterized by the presence of
erect, rounded sides, and with an oblong, obtuse apical
part. The new species also differs from M. ceratothal-
lis in terms of the absence of a pair of teeth near the
middle of the petals and on the gynostemium, as well
as by virtue of the obliquely ovate lateral sepals (vs
lateral semi-orbicular sepals). The new species may be
easily distinguished from M. priapus by its much longer
pedicels (up to 15 vs 2 mm) and ovaries (6 vs 1.5 mm
long) as well as by its short connate sepals.
Conservation status: According to the IUCN red
list criteria (IUCN 2011), this new species should be
Biodiv. Res. Conserv. 36: 7-10, 2014
Fig. 2. Myoxanthus ortizianus – inorescence and ower details
Explanations: A – inorescence, B – ower closeup, C – ower (side view), D – lip closeup. Photos by R. Medina
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10
classied as critically endangered (CR B2ab (III)),
based on the low number of known populations and its
restricted area of distribution.
Key to the species of Myoxanthus subgen. Myoxan-
thus, sect. Myoxanthus in Colombia (Luer 1992,
modied)
1. Floral bracts inated, enclosing the base of the sepals
.................................. M. monophyllus Poepp. & Endl.
1* Floral bracts not enclosing the base of the sepals ... 2
2. Sepals more than 3.5 mm wide .............................. 3
2* Sepals less than 3.5 mm wide ............................... 4
3. Petals ovate in the lower half, apically narrowed and
thickened .............................. M. speciosus (Luer) Luer
3* Petals ovate, abruptly contracted into an obtuse tails
..................................... M. ortizianus Kolan. & Szlach.
4. Lip apex narrowly rounded, gynostemium with a pair
of apical teeth .......................... M. afnis (Lindl.) Luer
4* Lip apex dilated, gynostemium without a pair of
apical teeth ..................... M. exasperatus (Lindl.) Luer
Acknowledgements. We would like to express our gratitude
to Ramiro Medina T. for his cooperation in the eld studies on
orchids of Putumayo and providing photos of the new species.
Myoxanthus ortizianus (Orchidaceae), a new species from southern Colombia
Marta Kolanowska & Dariusz L. Szlachetko
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