Psidium ratterianum Proença & Soares-Silva

Proença, C.E.B., Soares-Silva, L.H., Silva, P.Í.T. et al. 2010. Two new endemic species of Myrtaceae and an anatomical novelty from the Highlands of Brazil. Kew Bulletin 65: 463. DOI: https://doi.org/10.1007/s12225-010-9221-4

Type

Typus: Brazil, Distrito Federal, Brasília, 7 Dec. 2005, C. Proença, M. B. S. Campos & P. I. T. Silva 3068 (holotypus UB).

Morphology General Habit

Shrub to 0.3 m tall, cespitose; stems erect, the branches quadrangular, subalate, glandular, with sparse hairs when young; hairs colourless to whitish, weak and appressed

Morphology Leaves

Leaves increasing in size from proximal to distal nodes, ascending at c- 30° from the stem, the basal nodes with cataphyllar or much reduced leaves, leaf blade sessile or subsessile, elliptic to barely obovate, 4 – 7.4 × 1.1 – 4.8 cm, leaf ratio 1.6 – 4.6 times as long as wide, tannish brown in dried material, cartaceous at maturity, with dense, minute translucid glands when young; apex acute to subacuminate, fine-tipped and mucronate; base acute to obtuse; midvein sulcate above and prominent below; secondary veins 7 – 12 pairs, visible on both faces, strongly impressed adaxially, prominent abaxially, brochidodromous, forming a clear, crenate marginal vein, the first pair of laterals sometimes weak and disappearing into the margin, marginal vein 1.5 – 2.5 mm from the margin; upper surface with sparse hairs, the glands imperceptible to impressed in old leaves, lower surface with sparse hairs, when young the glands tan, barely prominulous, becoming flush with the leaf surface and darkening in old leaves; petioles 0 – 1 mm with scattered hairs

Morphology Reproductive morphology Inflorescences Peduncles

Peduncles axillary at basal nodes; quadrangular

Morphology Reproductive morphology Flowers

Flowers 1 – 3 (dichasium), pedicels 4 × 1 mm, quadrangular; bracteoles narrow-oblong, narrow-elliptic or falcate, blunt, c- 3.5 – 5 × 1 – 2 mm, persistent in old flowers and sometimes until fruiting; floral buds pyriform; hypanthium 3 – 4 mm; calyx lobes 5, deltoid, c- 1 mm × 1.5 long in bud, tearing to 3.5 mm, apiculate, closely hugging the petal globe, pubescent outside and densely sericeous inside, membranaceous; petal globe apparent, flushed red in bud, petals white, 6.5 – 8 mm long, not ciliate, densely glandular; staminal disk weakly 5-crenate, torn at anthesis, the petal scars c- 1 – 1.5 mm wide, the stamens c- 318 in 6 – 8 irregular whorls; stamens 4 – 7.5 mm long, anthers oblong, c- 0.5 – 1 mm long, apparently eglandular; style c- 7.5 – 10 mm, glabrous, glandular; ovary 3-locular; ovules 31 – 34 per locule, 2-seriate; stigma slightly expanded, funnel-shaped

Morphology Reproductive morphology Fruits

Fruits (immature) wide-ellipsoid, to c- 2 × 1 cm, glabrous and crowned by the flaring, persistent hypanthial remnants and calyx lobes; seeds not seen

Distribution

South America: Brazil, Distrito Federal.

Ecology

Psidium ratterianum is apparently a narrow endemic of the Distrito Federal; 1000 – 1200 m. It has been collected in campo sujo, and cerrado sensu stricto, i.e. grassy fields with sparse or dense scattered low trees and shrubs. Four flowering collections mentioned on the label that the area had recently burned, so this species may flower when triggered by burning. Flowering collection Proença et al. 3068 was observed by one of us (C.E.B.P.) being visited, apparently with stigmatic contact, by a large black Bombus (Apidae) bee minutes prior to collection.

Conservation

Conservation Status. Psidium ratterianum is apparently restricted to the Distrito Federal. There are four known populations within a radius of less than 5,000 km2, three of which are within reserves; of these, one was recently apparently eliminated by clearing and another is under threat by the invasive African grass Melinisminutiflora P. Beauv. (Martins et al.2004). This would qualify it in the IUCN (2001) category of Endangered EN B1, B2b(iii), that is, with a distribution <5,000 km2 in an area which has suffered continuous reduction in size and quality of habitat.

Note

Notes. Psidium ratterianum is possibly a new member of the recently revised Psidium grandifolium complex. This was treated by Landrum (2005) as having 3 species: Psidium australeCambess. (with three varieties), P. grandifolium Mart. and P. missionum D. Legrand. Our species appears to be closest to P. australe var. australe, and would key out to that species due to similar flowers and near glabrous, obovate leaves. It is immediately distinguishable from other species of the complex by the strongly bullate, ascending leaves, persistent bracteoles, expanded, funnel-shaped stigma and smaller fruits. Etymology. This name is a reference to James Alexander Ratter (Royal Botanic Garden, Edinburgh) for his pioneering studies of the flora of the Fazenda ÁguaLimpa, the Universidade de Brasília Field Station, where this species was first collected. Phenology. Flowering specimens were collected in December or January and fruiting specimens in January and March.