Tacinga subcylindrica

Naming history and growth form

Tacinga subcylindrica was described in 2003 as T. inamoena subsp. subcylindrica and raised to species rank in 2011. POWO accepts this rank. The name Opuntia subcylindrica, published under a different genus treatment in 2023, refers to the same taxon. [2-WWW]

Plants usually form dense, low patches reaching about 35 cm tall. Segments are oblong and almost cylindrical, with stems lying close to the ground. Larger spines are reduced, but areoles retain glochids. They differ from the typically flattened segments of T. inamoena primarily in their three-dimensional shape and the arrangement of new growth. [Menezes and Alves 2024] [Freitas et al. 2021]

Flowers and cytological characters

Flowers are orange-red. The identification key notes reddish hairs on the pericarpel. Fruits are described as globular, dark orange to red, without large spines. The cytological comparison gives 2n = 44, with 42 metacentric and two submetacentric chromosomes. This is a tetraploid level, also found in several other species of the genus. [Menezes and Alves 2024] [Freitas et al. 2021]

Habitat and confirmation of distinctness

The natural range covers northeastern Brazil and extends into Minas Gerais. In the population study, the species was associated particularly with gneiss outcrops, compared with the greater diversity of substrates occupied by T. inamoena. Habitat distinctness provides additional context for differences in habit and distribution. [Barrios-Leal et al. 2024] [2-WWW]

Analysis of 31 plants from ten locations showed a distinct genetic group with low variation in the markers studied within the species. Two plastid DNA regions and the nuclear gene PhyC were included. The authors regarded the results as supporting the separate status of T. subcylindrica. Estimates of divergence time from T. inamoena had a wide uncertainty interval and weaker node support, so separation of the groups studied remains the best-documented conclusion. [Barrios-Leal et al. 2024]