Historia rozpoznania

Tacinga mirim was described in the study by Menezes and Alves from 2024, while Menezes alone is the author of the botanical name. The material was previously known as T. palmadora. Reanalysis of specimens, field observations and chromosome comparison allowed the species to be distinguished. The holotype was collected on 30 December 2022 in Piabas, in Santa Quitéria municipality, Ceará. [Menezes and Alves 2024] [2-WWW]

Of seven re-examined specimens from Ceará, five were assigned to T. mirim and two remained unidentified to species. For these specimens, the earlier name T. palmadora is a misapplied identification rather than a synonym of the whole species. The epithet mirim comes from the word for “small” in Nheengatu. [Menezes and Alves 2024]

Stems, roots and armature

The plant has a strong taproot and partly prostrate stems 35–50 cm tall. Clumps are usually 60–90 cm wide, exceptionally about 2 m. Segments may be flattened or almost cylindrical, elliptic to obovate, usually 4,4–8,5 cm long, exceptionally 11 cm, and 2,4–4 cm wide. The surface is olive-green or dark green. [Menezes and Alves 2024]

Areoles are 2–3 mm in diameter and spaced 1–1,5 cm apart. They contain pale felt and golden glochids about 1 mm long. They most often produce one or two spines, sometimes three. Spine length usually falls within 10–26 mm, with a recorded range of 7–35 mm. Young spines are yellow, later becoming white or grey. Young segments bear small, rapidly shed leaves. [Menezes and Alves 2024]

Flowers and fruits

Flowers arise in the distal third of the segment. They are usually 3,1–3,6 cm long, exceptionally 4,1 cm, and 2,6–3,3 cm wide. Inner tepals are dark orange to red. The olive-green pericarpel usually has a smooth surface, with weak tubercles becoming apparent during dehydration. The four or five white stigma lobes project above the stamens. These are useful characters in comparison with T. palmadora. [Menezes and Alves 2024]

Fruits are globular to obovoid, 1,7–2,5 cm long and 1,4–1,7 cm wide, with an apical depression. The orange skin becomes purplish at full maturity. Areoles retain felt, glochids and bristles, and less often spines shorter than 1 cm. The pulp is translucent. In the described material, a fruit contained about 14 seeds, including underdeveloped seeds, while fully developed ones measured about 4 × 3 mm. [Menezes and Alves 2024]

Recruitment and karyotype

Terminal segments detach readily from the plant, especially during the dry season. Both these and mature fallen fruits can produce new shoots. Photographs and field observations in the protologue document this means of clump expansion. Flowers and buds were collected in July, December and January, and fruits in December and January. [Menezes and Alves 2024]

Cells contained 2n = 44 chromosomes, comprising 36 metacentric and eight submetacentric chromosomes. In the material studied, T. palmadora had 2n = 22. Chromosome size and the positions of fluorescent markers and ribosomal DNA loci also differed. Together, these characters support the species’ distinctness. Tetraploidy defines the number of chromosome sets, while the precise pathway of genome origin remains a separate evolutionary question. [Menezes and Alves 2024]

Range, habitat and conservation

Known sites are concentrated in northern Ceará. Most lie at about 190–360 m elevation, but one herbarium specimen comes from 978 m. The plant occupies shallow soils over crystalline bedrock and stony, sandy and clayey sites, including dry streambeds. It occurs in seasonally deciduous shrub and forest communities, both in sunlight and beneath tree cover. [Menezes and Alves 2024]

For the region where it occurs, the authors reported a mean annual temperature of 26–28°C, rainfall of 600–900 mm and a dry season lasting 6–8 months. These are habitat climate data. From known sites, they estimated an extent of occurrence (EOO) of 3033,22 km² and an area of occupancy (AOO) of 36 km², provisionally proposing category EN under criteria B1–2ab. The protologue assessment describes knowledge as of 2024 and has the status of the authors’ threat assessment. [Menezes and Alves 2024]

Synonyms and names in the literature

Tacinga palmadora sensu Menezes et al. 2011 pro parte [2-WWW]