IANKESTERIANA2 15-18 2001


 MYOXANTHUS VITTATUS (ORCHIDACEAE),
 A NEW SPECIES FROM COSTA RICA

 FRANCO PUPULIN1 and MARIO A. BLANCO2

 1 Jardin Botanico Lankester, Universidad de Costa Rica
 Research Associate, Marie Selby Botanical Gardens, Sarasota, U.S.A.
 P.O. Box 1031-7050 Cartago, Costa Rica. fpupulin@cariari.ucr.ac.cr
 2 Institute Centroamericano de Investigaci6n Biol6gica y Conservaci6n
 P.O. Box 2398-250 San Pedro de Montes de Oca, San Jose, Costa Rica
 Present mailing address: Herbarium, Florida Museum of Natural History, University of Florida
 385 Dickinson Hall, P.O. Box 117800 Gainesville, Florida 32611-7800, U.S.A.

ABSTRACT. The taxonomic position of Myoxanthus Poepp. & Endl. (Orchidaceae: Pleurothallidinae)
is discussed and Silenia Luer is maintained as a subgenus of Myoxanthus. A new species of
Myoxanthus is described and illustrated. Myoxanthus vittatus Pupulin & M.A. Blanco is apparently
endemic to the low, tropical wet forests of central Pacific Costa Rica, where it has been collected in
two different places. It differs from closely related species for the small size of the plant, the whitish
flowers, longitudinally striped with purple, the densely pubescent ovary, and the ligulate, obtuse lip.
The new combination Myoxanthus tomentosus (Luer) Pupulin & M.A. Blanco is proposed.

RESUMEN. Se discute la posici6n taxon6mica de Myoxanthus Poepp. & Endl. (Orchidaceae:
Pleurothallidinae) y se mantiene a Silenia Luer como subg6nero de Myoxanthus. Se describe y se
ilustra una nueva especie de Myoxanthus. Myoxanthus vittatus Pupulin & M.A. Blanco es aparente-
mente end6mico de los bosques tropicales de bajura en el Pacifico Central de Costa Rica, donde ha
sido recolectado en dos diferentes localidades. Difiere de las species afines por el tamafio pequefio
de las plants, por sus flores blanquecinas con estrias longitudinales purpura, por el ovario densa-
mente pubescente y por el labelo ligulado y obtuso. Se propone la nueva combinaci6n Myoxanthus
tomentosus (Luer) Pupulin & M.A. Blanco.

KEY WORDS: Orchidaceae, Pleurothallidinae, Myoxanthus, Myoxanthus sect. Silenia, Myoxanthus
vittatus, Costa Rica


 The circumscription of genera within the largest
tribes of the Orchidaceae has not yet reached a gen-
eral agreement among taxonomists. The subtribe
Pleurothallidinae, restricted to the tropics and sub-
tropics of the New World, is perhaps the largest
taxonomic orchid group, with 28 genera and an
estimation of more than 3000 species (Dressler
1993).
 The genus Myoxanthus was first described by
Endlicher on M. monophyllus (Poeppig &
Endlicher 1835), based on a plant collected in the
Peruvian department of Huanuco by Poeppig. In
1847 another species currently assigned to
Myoxanthus was identified as a distinct genus and
described as Duboisia by Karsten (later renamed


Dubois-Raymondia Karsten due to the priority of
Duboisia R. Br. in the Solanaceae) (Karsten 1847,
1848). A third attempt to assign species of
Myoxanthus to a new genus was made by Barbosa
Rodrigues (1882), who described Chaetocephala to
accommodate its former Restrepia lonchophylla. In
the opinion of leading orchid taxonomists at that
time, notably Lindley, Reichenbach, and Cogniaux,
the criteria selected to define the new genera were
insufficient to sustain the proposals, and
Myoxanthus species were newly submerged into
the conglomerate genus Pleurothallis.
 It was not until 1982 when the genus
Myoxanthus was resurrected by Luer who recog-
nized 34 species sharing a combination of