Mimosa myrioglandulosa V.F.Dutra & F.C.P.Garcia

Dutra, V.F. & Garcia, F.C.P. 2013. Two new species and one new variety of Mimosa sect. Habbasia (Leguminosae: Mimosoideae) from Central Brazil. Kew Bulletin 68: 163. DOI https://doi.org/10.1007/s12225-012-9427-8

Type

Type: Brazil, Minas Gerais: Delfinópolis, trilha da Escada de Pedras, Nakajima et al. 3816 (holotype HUFU!; isotypes K!, VIC!).

Morphology General Habit

Shrubs 0.5 – 3.8 m tall

Morphology Stem

Stems glandular, gland sessile

Morphology Leaves

Leaves with 4 – 11 pairs of pinnae; stipules 4 − 7 × 1 mm long, lanceolate, externally strigose or glandular, internally glandular, 3 – 4-nerved, deciduous; petiole 15 – 34 mm long, glandular; rachis 3.5 – 17.8 cm long, glandular, the longer interfoliolar segments 10 – 18 mm long; spicules present, c- 2 mm long; pinnae 3 – 11 cm long, glandular; leaflets 17 – 39 pairs, 3 − 10 × 1 − 3 mm, oblong, apex acute, obtuse or mucronulate, base oblique, glabrous, margins sparse-glandular or glabrous, 1 – 4-nerved; paraphyllidia subulate

Morphology Reproductive morphology Inflorescences Capitulum

Capitula without filaments 8 − 14 × 8 − 13 mm, globose, axillary or in terminal pseudoraceme, 1 – 3 per node; peduncles 20 – 26 mm long, glandular; flower buds in capitula prior to anthesis concealed by bracts

Morphology Reproductive morphology Flowers

Flowers heteromorphic, the lower ones staminate; bracts 4 – 6 × 0.8 mm long, lanceolate, strigose, glandular or no; calyx 0.7 – 1 mm long, campanulate or tubular, lobes irregular, ciliate or strigose; corolla 4-merous, 4 – 6.5 mm long, campanulate, tube 2.5 – 4.5 mm long, glabrous, lobes glabrous or glandular, 1-nerved; 8 filaments, 9 – 21 mm long, pink, free; ovary 1.5 – 2 mm long, glandular, style 11 – 21 mm long

Morphology Reproductive morphology Fruits

Fruit 43 − 45 × 7 − 8 mm, glandular

Morphology Reproductive morphology Seeds

Seeds unknown

Figures

Fig. 2.

Distribution

Brazil: Minas Gerais. Endemic to the region of Sacramento and Delfinópolis, in the southwest part of Minas Gerais (Map 1).

Ecology

Rocky fields.

Conservation

IUCN category (2001) Endangered (EN, criteria B2ab(iii) + D). The species occurs in small, isolated and restricted populations in two localities subjected to intense human activity, since the region's economy is based on cereal crops, Pinus and Eucalyptus monocultures, tourist attractions such as waterfalls and caves, and the extraction of minerals, mainly quartz, the substrate in which Mimosa myrioglandulosa grows.

Phenology

This species has been observed in flower in September and October and with fruits in April and October.

Note

Mimosa myrioglandulosa can be distinguished from the other species of the series Pachycarpae by a unique combination of the following characters: vegetative structures (stems, petioles, rachis of the leaf and pinnae) and reproductive structures (lobes of the corolla, ovary and fruit) lacking tector trichomes and covered by sessile glands. The shrub architecture and appearance of the fruit suggest affinity with M. maguirei, but M. myrioglandulosa differs from it by having the branches covered with glands, giving a vitrious appearance to the plant, and leaves with shorter petioles and a larger number of pinnae. M. myrioglandulosa is similar vegetatively to M. melanocarpaBenth., which belongs to series SetosaeBarneby, but differs from it by having valvately dehiscent fruit of the type ‘sacelo' (vs a conventional craspedium). Mimosa myrioglandulosa is placed in sect. Habbasia ser. PachycarpaeBenth., because its fruit is a sacelo, which is characteristic of the series. The diagnostic characters of series Pachycarpae and how the species differ in this series are discussed under M. foliolosa var. grandibractea. The specific epithet myrioglandulosa refers to the number of glands that cover the stems, petioles, leaf rachises, ovaries, and fruits of the species. Related to Mimosa maguireiBarneby but it differs by its glandular stems (vs glabrous).