Background:

Thelocactus leucacanthus ssp. schmollii (Cactaceae) has a distribution restricted to Querétaro, and it is categorized as a taxon of least concern in the IUCN red list, and in CITES Appendix II, but it is not found in any category of NOM-059-SEMARNAT-2010.

Questions:

What is the mating and breeding systems of T. leucacanthus ssp. schmollii? What kind of floral rewards does it offer to its visitors, and which are its potential pollinators?

Studied species:

Thelocactus leucacanthus ssp. schmollii (Cactaceae)

Study site and dates:

Peñamiller, Querétaro, Mexico, during 2018.

Methods:

To determine the mating system, controlled pollination treatments were made, establishing the fruit percentage and seed mean that were formed per treatment. Cruden’s outcrossing index (OCI) was determined. The nectary morpho-anatomy was described, and the floral visitors were recorded.

Results:

T. leucacanthus ssp. schmollii is xenogamous according to OCI, and it has a strict outcrossing system according to the pollination treatments. The main pollinators are bees from the genus Lasioglossum, and the main reward is pollen.

Conclusions:

Since this taxon only produces seeds by xenogamy, the alterations in the environment caused in the study site reduce the population size, limiting the number of possible mating partners and in consequence, diminishing the genetic diversity.