VERA-CALETTI, PATRICIA1* and TOM WENDT2. 1Area de Biologia, Universidad Autonoma Chapingo, km 38.5 carretera Mexico-Texcoco, 56230 Chapingo, Estado de Mexico, Mexico; 2University of Texas Herbaria, Plant Resources Center, University of Texas, Austin, Texas 78713. - A revision of the genus Calatola (Icacinaceae) in Mexico.
The family Icacinaceae is represented in Mexico by four genera of
trees (Calatola, Oecopetalum, Mappia, and Ottoschulzia),
of which only Calatola is dioecious. Calatola is a
Neotropical genus previously considered to consist of about six
species, of which two (C. mollis Standl. and C.
laevigata Standl.) were reported for Mexico, where the genus
occurs in lowland rain forest and middle elevation cloud forest. A
unique feature of Calatola is the presence in all parts of the
plant of a compund, identified as a flavonoid in the present study,
that oxidizes to a blue-violet color upon exposure to air. The present
revision, which incorporates data from traditional morphology, field
characters, chromosome numbers, pollen, germination and seedling
morphology, recognizes five species for Mexico, adding C.
costaricensis Standl. and two undescribed taxa to those previously
known. C. laevigata is shown to be a rare species of the
Pacific slope, while populations of the Mexican Gulf slope, Guatemala,
and Belice previously referred to this taxon represent an undescribed
species. C. costaricensis displays geographic variation and
possible intergradation with C. mollis and thus requires
further study. The chromosome counts of n = 14 from two species (and n
= ca. 14 from two others) represent the first counts for the genus,
first counts for the family in the New World, and a new number for the
family. Seed germination occurs in ca. 7-9 month in situ and over 12
months ex situ. All species in Mexico are represented by either small
or very dispersed populations and are thus of conservation concern.
Key words: Calatola, Icacinaceae, Mexico