Microlicia acuminata Naudin (1845: 179),

non Microlicia acuminata Cogniaux (1891: 55) .

≡ Chaetostoma acuminatum (Naudin) Cogniaux (1883: 35).

In prov. Goyaz [Goiás] legit Gardner. Ex herb. Deless. [in the protologue].

Lectotype (designated here):—[BRAZIL]. Prov. Goyaz [Goiás]: Gardner 3730 [sheet, see Triana (1872) and Cogniaux (1883)] (K000530400!, isolectotypes K000530398!, on the left side) .

= Chaetostoma acuminatum var. ramosissima Cogniaux (1883: 36) . In campis arenosis humidisque ad Araracoara prov. Minas Geraës: Riedel n. 2211 [in the protologue]. Lectotype (designated here):—[BRAZIL]. Riedel 2211 [sheet] (BR0000005184606!, isolectotypes C!, E00285711!, photo of B† at F [F0 BN016573!], K000530397!, LE!, M!, P02297772!, P02297773!, W!).

= Microlicia castrata Naudin (1849: 230) . ≡ Chaetostoma castratum (Naudin) Cogniaux (1883: 36) . In Brasiliae australis prope Salinas prov. Goyaz [Goiás], Gardner, Cat. N° 3732 [in the protologue]. Type:—Brésil [BRAZIL]. Province de Goyaz [Goiás]: M. Gardner 3732 [sheet] (holotype P02297658!, isotypes BM000832641!, BM000832642!, BR0000005217748!, F!, G00318382!, K000567178!, K000530578!, P02297657!, P02297659!), see Martin & Cremers (2007) and Koschnitzke & Martins (2007), syn. nov.

= Microlicia oxyanthera Naudin (1849: 230) . ≡ Chaetostoma oxyantherum (Naudin) Triana (1872: 25) . In paludosis Brasiliae australis prope Salinas prov. Goyaz [Goiás], Weddell, Cat. N° 2166 et 2119 [in the protologue]. Lectotype (designated by Koschnitzke & Martins 2007):—Bresil [BRAZIL] Central (Salinas), H.A. Weddell 2166 [sheet] (P00481612!, isolectotypes: F! [fragment], P00481613!, P00481614!), syn. nov.

Remaining syntype:— BRAZIL. Goiás: Salinas, May–July 1844, H.A. Weddell 2119 (P00481615!) .

= Microlicia oxyanthera var. β albiflora Naudin (1849: 231). In paludosis Brasiliae australis prope Salinas prov. Goyaz [Goiás], Weddell, Cat. N ° 2605 [in the protologue]. Type:—Bresil [BRAZIL]. Goyaz [Goiás]: campos au peu marécageux [sheet], H.A. Weddell 2605 (holotype P00481659!), syn. nov.

Notes: — Naudin (1845) described M. acuminata based on Gardner from Herb. Deless. (currently at G). Triana (1872) and Cogniaux (1883, 1891) cited Gardner 3730 when synonymizing it in C. oxyantherum and C. acuminatum, respectively. However, despite our searches at herbarium G (and other herbaria), we did not find corresponding to the original material cited in the protologue (i.e., Gardner s.n.). Therefore, we follow Triana’s and Cogniaux’s interpretation who considered the collection Gardner (in the protologue) as Gardner 3730.

Although there are three sheets of M. castrata at P, two sheets (P02297657 and P02297659) were only acquired in 1904 (see Bureau 1904; Le Bras et al. 2017). Therefore, we assume the sheet with a short description handwritten by Naudin as holotype of M. castrata .

Microlicia acuminata was described by Naudin (1845) as having quadrangular branches with setose trichomes, ovate or lanceolate leaf blades (7–10 × ca. 0.7 mm), acuminate at the apex with a terminal trichome, only with one central vein, long trichomes and hirsute indumentum on the leaf blades, entire and setose-ciliate margins, purple petals, and axillar flowers or at the apex of the branches. Triana (1872), when transferring M. oxyanthera to Chaetostoma De Candolle (1828: 112), synonymized M. acuminata and M. castrata under C. oxyantherum . Despite Cogniaux (1883) having accepted this transference to Chaetostoma, he considered C. acuminatum, C. castratum, and C. oxyantherum as three distinct species. Koschnitzke & Martins (2007) returns to Naudin’s recognition and also propose C. acuminatum var. ramosissima as synonym of M. acuminata . Analyzing the type collection of M. acuminata, M. castrata, M. oxyanthera, and M. oxyanthera var. albiflora, we concluded that the variation found in the original material of these entities (see Koschnitzke & Martins 2007) overlap and are insufficient to recognize them as different taxa.

More than 30 collections from Goiás and Mato Grosso states were examined, and we observed a morphological variation in M. acuminata, mainly regarding the indumentum of the branches, leaves, hypanthium, and sepals, to sparse a densely distributed. Despite this variation, we can recognize M. acuminata by its indumentum of setose trichomes mixed with spherical glands, sessile and ascending leaves with acuminate apices, purple or pink petals, sometimes cream at the base, rarely white, oblong hypanthia, and long and lanceolate sepals. The stamens are yellow, subisomorphic with polysporangiate, and ovate-oblong anthers with short rostrate apices.