Relative importance of two bat species as pollinators of Neobuxbaumia tetetzo (Cactaceae): Evidences from morphometric and pollen load analyses.

Neobuxbaumia tetetzo is a columnar cactus whose flowers are visited by the bat species Choeronycteris mexicana and Leptonycteris yerbabuenae. Although both bat species are considered the pollinators of N. tetetzo, the probability of pollination of each bat species has not been estimated. In this study, we determine the relative importance of C. mexicana and L. yerbabuenae as pollinators of N. tetetzo. The probability of pollination was estimated using two different approaches: (i) morphological correspondence between head (linear traits [total head length, snout length, and face height and width]) and cranial traits (shape traits) of bats and flower traits (linear [internal floral tube length including and excluding the nectary, corolla diameter, stamen length, style length, and corolla tube diameter] and shape traits), and (ii) pollen load analyses to estimate the percentage of occurrence (PO) and the pollination probability index (PPI). Our results showed a lack of a significant correspondence between both head and cranial traits of C. mexicana and the flowers of N. tetetzo, and linear morphological correspondence between total head length of L. yerbabuenae and flower length. Pollen loads of C. mexicana were composed by seven different pollen types, its PO and PPI were 41.87 ± 9.53% and 0.29, respectively. Leptonycteris yerbabuenae pollen loads were composed by three pollen types, with a PO of 78.29 ± 13.67% and a PPI of 0.67. Our results suggest that whereas C. mexicana has a low constancy to the flowers of N. tetetzo, L. yerbabuenae has a higher probability of pollination. [ABSTRACT FROM AUTHOR]