WMTTEN ET AL. Relationships of Zygopetalinae


and not slit-like.

Dressier (1993), who included Vargasiella in
Zygopetalinae, mentioned possible placement in its
own subtribe; Romero and Camevali (1993) validated
the subtribe Vargasiellinae, which was also recognized
by Szlachetko (1995). We were unable to obtain
extractable material of this genus for inclusion in this
study and its placement remains uncertain.

Our sampling within the Huntleya grade is more
complete, especially for Central American taxa, and
some conclusions and taxonomic transfers are justified
by the analyses. The discussion is arranged by the
genera recognized in Figs. 4 & 5, although Hoehneella
is not in the figure (see discussion below).

 Cryptarrhena This genus (two species) is
morphologically anomalous within the subtribe and
is isolated on a very long branch. Its placement within
the subtribe in the combined cladogram is unresolved,
but it is sister to the Huntleya clade in many of the
shortest trees. The spicate, pendent inflorescences
have numerous, small flowers, whereas most of the
Huntleya clade have single-flowered inflorescences.
Cryptarrhena lunata has fleshy, strongly keeled leaves
and lacks pseudobulbs, whereas C. guatemalensis has
thinner leaves and small pseudobulbs. Nevertheless,
several characters link Cryptarrhena to other genera
of Zygopetalinae. The anchor-shaped lip is similar to
that of Dichaea, and the column bears a conspicuous
clinandrium (hood) similar to those of Huntleya and
Chaubardia, and a distinct basal tooth. Within the
subtribe, many-flowered inflorescences are also present
in Galeottia, Warrea, Warreopsis, and Zygopetalum,
among others.

Chaubardia Florally, Chaubardia (three species)
is very similar to Huntleya; both possess flat, open
flowers with rhomboid lips bearing a conspicuously
toothed callus. The columns of both genera possess
lateral wings and often a hooded clinandrium, but the
sepals and petals are narrower than those of Huntleya.
Chaubardia is characterized by small, inconspicuous
pseudobulbs at the base of fan-shaped growths, whereas
Huntleya species lack pseudobulbs. The molecular data
strongly support monophyly of Chaubardia and its
separation from Huntleya.

Hoehneella We were unable to obtain extractable
material of this small genus of 1 or 2 species.
Morphologically, it is similar to Huntleya and


Chaubardia. According to Senghas and Gerlach
(1992-1993), the plants possess small pseudobulbs
similar to those of Chaubardia and its viscidium
is transversely elliptic and lacks a stipe. [Type: H.
gehrtiana (Hoehne) Ruschi]

Huntleya This is a distinctive and easily recognized
genuswithabout 13 species. Theplantslackpseudobulbs,
and some species possess elongate rhizomes separating
the fan-shaped growths. The flowers are large, star-
shaped, and flat with relatively broad sepals and petals
and are probably fragrance-reward flowers pollinated
by male euglossine bees.

Dichaea Dichaea is the largest and most distinctive
genus in the subtribe (about 111 species) and is widely
distributed from Mexico to Brazil. It is characterized
by long, many-leaved, pseudomonopodial stems that
are pendent in many species. Solitary flowers bearing
an anchor-shaped lip are produced successively along
the leafy stems, and all species are probably pollinated
by fragrance-collecting male euglossine bees (although
autogamous forms occur). The genus is monophyletic
and the representatives of Dichaea are on a relatively
long branch and are remarkable for the high levels of
sequence divergence among the species; the branch
lengths within Dichaea are greater than the lengths
among most genera within the subtribe. These data
indicate that sequencing of ITS and plastid regions
has great potential for resolving species relationships
within this moderately large genus. Conversely, the
low levels of sequence divergence within many genera
(e.g., Kefersteinia, Bollea, Pescatorea) indicate that
sequencing these regions for additional taxa will not
help to clarify relationships within these genera.

The remaining taxa within the Huntleya clade (Fig.
4) include many species that have been included in
Chondrorhyncha. Generic delimitation within this
clade has been difficult and many species have complex
nomenclatural histories as orchidologists have shifted
them from one genus to another. This taxonomic
confusion probably reflects repeated evolutionary
changes in pollination mechanisms that produced
homoplasious floral morphologies. Many species in this
clade produce gullet flowers that appear to be nectar
deceit flowers for long-tongued visitors, probably
nectar-foraging euglossine bees (Ackerman 1983). The
funnel-shaped lips do not produce a true spur, but do
have a notch on either side of the base of the lip that
permits passage of a bee's tongue. The lateral sepals are
swept back and revolute, forming a tubular false spur


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