Cuban Pinguicula: The Recent Division of Pinguicula filifolia into Subspecies

Pinguicula filifolia

I've been somewhat fascinated with Caribbean Pinguicula as of late, and recently found a trove of recent scientific research on Pinguicula filifolia. In nature, P. filifolia is an annual, growing on Cuban sandy savannas from May to February, when those savannas experience both high humidity and frequent rains. Seeds rest atop the sandy soil before germinating at the beginning of the rainy season.

Pinguicula filifolia in habitat

Interestingly, a lot of research has been conducted on P. filifolia (2n = 18), as well as its relatives, Pinguicula cubensis and Pinguicula albida. For instance, P. filifolia, which grows in sandy sites that are frequently flooded, is hypothesized to have evolved upright leaves because these (1) allow for greater light absorption, and (2) prevents rot more effectively than a rosetted leaf. Further, studies of different populations of the three Cuban species have revealed a lot of interesting information, including the fact that, for P. albida and P. filifolia, there appear to be two population groups with unique phenotypic characteristics. Either specific environmental conditions are selecting for specific phenotypes, or population isolation has caused a divergence in gene flow.

Habitats of Cuban Pinguicula

Previous study had indicated that the three species of Cuban Pinguicula all shared a common ancestor, and evolved to become separate species due to population separation and environmental conditions.

Distribution of subspecies of Pinguicula filifolia

This year, it was determined that the differences between populations of P. filifolia warranted division of P. filifolia into two subspecies - subspecies filifolia and subspecies alba. From the results:

Both subspecies share common morphological features, mainly those regarding vegetative characters, such as linear-filiform erect leaves; although, they differ in several quantitative and qualitative traits. P. filifolia subsp. alba differs from the typical subspecies in the number and length of leaves; it also has up to ~13 inflorescences per plant which are larger than in subsp. filifolia. The new subspecies shows only white flowers with oblong-spathulate lobes, a shorter and wider conical spur that forms an angle of 99°–110° with the tube and smaller fruits. Seeds are smaller and exotesta cells show no crests like those observed in the typical subspecies. P. filifolia subsp. alba is so far known only from the type locality in northwestern Pinar del Río province in Cuba. 

Always exciting to report on such thorough scientific work. I look forward to learning more about Cuban - and other Caribbean - Pinguicula.