Type: — BRAZIL. Santa Catarina: Garuva, Serra do Quiriri, Pedra Cabeluda, Arredores do Monte Crista, 17 March 2013, F.S. Meyer 1682 (holotype: UEC!, Isotypes: MBM!, FURB!, UPCB!)

Diagnosis: — Chaetogastra cristaensis differs from Tibouchina urbanii Cogniaux (1888: 602) by the thick chartaceous leaves, leaf margins with trichomes 3–6 mm long, vs. thinner, membranaceous leaves and leaf margins with trichomes 0.4–1.3 mm long in T. urbanii.

Subshrub with sympodial growth, 30–70 cm tall. Branches sparse or moderately hirsute, trichomes 0.5–4 mm long, both glandular and not glandular, erect, the base rounded, slightly enlarged, not immersed, not forked. Petiole 2.9–11.6 mm long, sparsely to moderately hirsute, trichomes 1.4–5.5 mm long, glandular and not glandular mixed, erect, the base rounded, enlarged to slightly enlarged, not immersed, not forked; blade 3.2–8.3 × 1.1–4.3 cm, chartaceous, ovate or elliptic-ovate, surface flat, patent in dry specimens, apex acute or acuminate, base obtuse, margins crenulate, long-ciliate, trichomes 3–6 mm long, not glandular, erect or curved, the base linear and not enlarged, immersed, not forked, adaxial surface glabrous or sparsely setose-strigose, trichomes distributed on the whole surface or just on the apical portion and near the margins, 6–12 mm long, both glandular and not glandular, appressed or curved, the base linear and not enlarged, immersed, forked or not, abaxial surface glabrous or sparsely setose, trichomes 3–5 mm long, both glandular and not glandular, curved, the base rounded and slightly enlarged, not immersed, not forked; veins 5, first and second lateral pairs confluent. Thyrsoid short or elongate, cymes axillary and terminal, flowers lax; internode of the inflorescence base 5–6.7 cm long; bracteoles 1.3–3.5 × 0.8–2 mm, ovate or orbicular, glabrous on both surfaces, margins long-ciliate, trichomes 0.3–1.2 mm long, not glandular, curved, the base rounded, slightly enlarged, not immersed, not forked. Flowers 4(–5)–merous; hypanthium 5–7 × 3.4–5 mm, obovate, slightly constricted in its apical portion, green to vinous, smooth (without longitudinal ribs), moderately setose, trichomes 2–4 mm long, both glandular and not glandular, inclinate, the base rounded and not enlarged, not immersed, not forked; sepals 3.4–5.2 × 1.8–2.4 mm, narrowly triangular but with a wide base, apex acuminate, abaxial surface glabrous or with indumentum similar to the hypanthium, but concentrated on the central portion, adaxial surface glabrous, margins long-ciliate, trichomes 0.7–1.9 mm long, not glandular, curved, the base rounded, slightly enlarged, not immersed, not forked; petals 27.5–29.4 × 22.1–23.4 mm, purple, obovate, apex obtuse or apiculate, margins short-ciliate, trichomes 0.2–0.4 mm long, both glandular and not glandularboth, erect, the base rounded, not enlarged, not immersed, not forked; stamens 8(–10), antepetalous with filaments 4.2–6 mm long, pedoconnective 0.1–0.5 mm long, anthers 4.2–5.8 mm long, yellow, anther pore ca. 0.2 mm wide, antesepalous with filaments ca. 6.5 mm long, pedoconnective 1–1.2 mm long, anthers 6.4–7.9 mm long, yellow with lilac spots, anther pore ca. 0.2 mm wide, both anthers with attenuate apex, apical-ventral pore and pedoconnective appendages with apex obtuse; ovary 3.8–6 × 2–2.9 mm, apex sparse or moderatly pubescent with trichomes 0.3–1 mm long, both glandular and not glandular, erect, the base rounded and not enlarged, not immersed, not forked; style 12–15 mm long, apex curved, glabrous. Capsule 10.3–14.5 × 4.3–6.2 mm, smooth (without longitudinal ribs).

Paratypes:— BRAZIL. Santa Catarina: Garuva, Serra do Quiriri, Monte Crista e Pedra Cabeluda, 16 March 2001, F.S. Meyer & E.J. Comitti 1037 (FURB!, UPCB!); ibidem, F.S. Meyer & E.J. Comitti 1038 (MBM!); ibidem, F.S.Meyer & E.J. Comitti 1039 (MBM!, UPCB!); ibidem, F.S. Meyer & E.J. Comitti 1040 (NY!, UPCB!, US!); ibidem, F.S. Meyer & E.J. Comitti 1041 (UPCB!); ibidem, F.S. Meyer & E.J. Comitti 1042 (MBM!, UPCB!); ibidem, F.S. Meyer & E.J. Comitti 1043 (UPCB!); ibidem, F.S. Meyer & E.J. Comitti 1044 (UPCB!); ibidem, 17 March 2013, F.S. Meyer 1677 (UEC!); ibidem, F.S. Meyer 1686 (UEC!, UPCB!); ibidem, 09 February 2016, P.C. Ferreira & V. Ariati 119 (MBM!).

Distribuition and habitat:— Chaetogastra cristaensis occurs only in the state of Santa Catarina (Figure 1C), between 870- 1.000 m, in upper montane Atlantic Rain Forest and High-altitude grasslands at the “Serra do Quiriri” (26° 4’40.79”S- 48°55’43.66”W), near the peak of “Monte Crista” (Figure 7E), with small populations.

Phenology:—Flowering and fruiting from January to March.

Conservation status:—This species can be considered Critically Endangered according to IUCN’s category A2 (2012). The Area of Occupancy is around 480 km 2, and Extent of Occurence 1.028 km 2. The only known population comes from an unprotected area, with frequent timber removal for use in bonfires; the area has camping sites that are expanding, and there are fire reports related to them.

Etymology:—The epithet is refers to the locality of “Monte Crista”, only site of occurrence until the moment.

Affinities: — Chaetogastra cristaensis is similar to Tibouchina urbanii due to the sympodial growth, ovate leaf blades, and the antesepalous stamens with short pedoconnectives, 0,4–0,8 mm in T. urbanii, and 1–1.2 mm long in C. cristaensis. Chaetogastra cristaensis differs from T. urbanii by the differences pointed in the diagnosis. Chaetogastra cristaensis is also similar to Chaetogastra crassifolia (see comments under this species).