Didymoglossum bucinatum: a new combination in subgenus
Didymoglossum (Hymenophyllaceae); and a key for Mexican species
A new combination is made for a quite rare fern species, Didymoglossum bucinatum, endemic to the states
of Hidalgo and Oaxaca, Mexico. A description, illustration and distribution map are provided, as well as a key to
the eleven species of Didymoglossum known from Mexico.
Se hace una nueva combinación de una especie de helechos muy rara y escasa, Didymoglossum bucinatum,
endémica en los Estados de Hidalgo y Oaxaca, México. Además se proporcionan, una descripción, ilustración y
mapa de la distribución, así como una clave para las once especies de Didymoglossum de México.
Cloud forest, endemic species, Flora, nomenclature, Pteridophyta, taxonomy.
Bosque mesóﬁlo de montaña, especies endémicas, Flora, Pteridophyta, nomenclatura, taxonomía.
As a result of ﬂoristic and biodiversity studies on the
species of ferns and lycophytes from Mexico (Palacios-
Rios 2016a, b), it was observed that the following species,
previously treated as a species of Trichomanes L., has
characteristics that place it in the genus Didymoglossum
Desv., which lacks roots but has root-like rhizomes
(Schneider 2000). These are short, leaﬂess rhizomes
that are densely pubescent with adhesive trichomes. The
species has catadromous blade venation, and unusually
in this genus, false veins are present: these are elongate
collenchymatous cells that appear as faint streaks
between and parallel to the main veins. The necessary
new combination is made here.
Didymoglossum is represented in Mexico by eleven
species that occur in the mountains in the central and
south regions. The species are: Didymoglossum
angustifrons Fée, D. bucinatum (Mickel & Beitel) M.
Palacios comb. nov., D. curtii (Rosenst.) Pic. Serm.,
D. ekmanii (Wess. Boer) Ebihara & Dubuisson,
D. godmanii (Hook.) Ebihara & Dubuisson,
D. hymenoides (Hedw.) Copel., D. krausii (Hook. &
Grev.) C. Presl, D. membranaceum (L.) Vareschi, D. ovale
E. Fourn., D. petersii (A. Gray) Copel. and D. reptans
(Sw.) C. Presl. They grow in wet forests up to c. 1500
m, usually as low-trunk epiphytes and sometimes on
moss-covered rocks. Often they are overlooked be-
cause of their small size.
Didymoglossum is a pantropical genus of dwarf
epiphytes with c. 30 species; there are two subgenera,
Didymoglossum and Microgonium (C. Presl) Ebihara & K.
Iwats. According to Ebihara et al. (2006) the subgenus
Didymoglossum with more than 20 epilithic or low-
epiphytic species, is mainly found in the New World,
all lack continuous submarginal false veins. On the
other hand, subgenus Microgonium with more than 10
epilithic or low-epiphytic species, mainly in the Old
World (with only four New World species), is
characterised by the absence of stellate hairs on the
leaf margins and by the presence of continuous
submarginal false veins (Ebihara & Iwatsuki in
Ebihara et al. 2006; Senterre et al. 2017).
The genus Didymoglossum belongs to the family
Hymenophyllaceae Mart. (with two subfamilies, nine
genera, and an estimated 434 species), in the subfamily
Trichomanoideae C. Presl (with eight genera and an
estimated 184 species) according to PPG (2016). In
taxonomic treatments of Hymenophyllaceae traditionally,
only two genera had been recognised: Hymenophyllum Sm.
(as a subfamily 250 species) with their bivalve involucres,
and Trichomanes L. (as subfamily Trichomanoideae with
184 species) with tubular involucres.
Desvaux ﬁrst described the genus Didymoglossum in
1827. Christensen (
1906) placed it as one of eight
subgenera within Trichomanes: Achomanes, Cardiomanes,
Cephalomanes, Didymoglossum, Eutrichomanes, Feea,
Accepted for publication 9 May 2018.
Instituto de Ecología, A.C., km 2.5 carretera antigua a Coatepec # 351, Congregación El Haya, Xalapa, 91070, Veracruz, México.
Instituto de Biotecnología y Ecología Aplicada (INBIOTECA) de la Universidad Veracruzana, Veracruz, Mexico.
KEW BULLETIN (2018) 73:24
ISSN: 0075-5974 (print)
ISSN: 1874-933X (electronic)
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2018