Identification and stems
Tacinga gladispina, described in 2021, forms upright clumps 40–60 cm tall. Roots are fibrous, branched and shallowly distributed. The green, flattened segments are 9–15 cm long, 6–8 cm wide and 0,5–1,3 cm thick. Surface tubercles are only weakly developed. [Freitas et al. 2021]
On mature segments, an areole usually produces one, less often up to three, stiff spines 1–1,5 cm long. Their base is flattened, and the white middle portion grades into a brown tip. Young segments may not yet have larger spines. Armature of this form distinguishes the species from the similar T. inamoena, which usually lacks large spines. [Freitas et al. 2021]
Flowers, fruits and recruitment
Flowers are 2,5–3,3 cm long and 1,5–2,5 cm wide. The perianth consists of 18–24 tepals arranged in three series. The outer ones are reddish with orange margins, and the inner ones orange and recurved. The fruit is slightly flattened, globular, about 2,5–2,7 cm wide, orange-green, with glochids and no larger spines. [Freitas et al. 2021]
White, fibrous pulp surrounds 58–66 seeds per fruit in the described material. This count also includes underdeveloped structures and those lacking an embryo. Fruits ripened after approximately two months and fell off quickly. Both detached segments and fallen fruits could produce new shoots, contributing to clump expansion. [Freitas et al. 2021]
At the natural site, flowering was observed in November and December. Additional flowers developed in May in the collection. These dates refer to the Brazilian research material and indicate phenological plasticity between the site and the collection. [Freitas et al. 2021]
Range and cytological characters
The protologue was based on a population from Morro do Chapéu in Bahia, at about 900 m elevation. Plants grew on sandy substrate among shrubby Caatinga vegetation. At the time of the study, about 500 plants were estimated over an area of 32 000 m². The authors identified a small range and habitat transformation as the main threat factors. [Freitas et al. 2021]
The chromosome number is 2n = 44, and the described karyotype contains 40 metacentric and four submetacentric chromosomes. Spine, fruit, seed and karyotype characters together support the species’ distinctness. Its similarity to T. inamoena and the presence of other Tacinga in the region explain why the description required comparison of several character sets. [Freitas et al. 2021]