Myrcia macaca Sobral & M. A. D. Souza 2015, nov. sp.
Creators: name: Sobral, Marcos
name: Souza, Maria Anália Duarte De
name: Luize, Bruno G.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Myrtaceae
Myrcia
Myrcia macaca

description: 3. Myrcia macaca Sobral & M.A.D. Souza, nov. sp.
Type: BRAZIL. Roraima: mun. Pacaraima, BR-174, a 15 km de BV-8 em direção norte, Cachoeira dos Macacos, 13 May 1998, C.A. Cid, J. Lima & D.F. Coêlho 11603 (holotype, INPA!). Figure 3.
This species is apparently related to Myrcia porphyrea, from which it is distinguished through the pilose blades (versus glabrous in M. porphyrea), smaller inflorescences, branching only once (to 15 flowers vs. more than 30, inflorescences branched up to three times) and ovaries with three locules (vs. two). It can also resemble Myrcia crispa, from which it is separated through the lighter trichomes (always brownish in M. crispa), blades with the abaxial surface visible through the indumentum (vs. completely concealed), flowers with an evident calyx tube (vs. calyx tube absent) and ovaries with three locules (vs. two).
Shrub to 3 m. Twigs cylindrical, the young ones densely covered with white, rufous or blackish simple erect or slightly ascending trichomes 0.8–1 mm, the adult ones glabrescent, grey and moderately longitudinally striate; internodes 20–30 × 2 mm. Leaves with petioles 2–4 × 1.5–2.1 mm, adaxially applanate and densely covered with trichomes as the twigs; blades elliptic or widely elliptic, occasionally ovate, 28–67 × 19–47 mm, 1.4–1.8 times longer than wide, chartaceous and discolorous, lighter abaxially, when dry, the adaxial face lustrous or shining, glabrous except for the occasionally pilose midvein, in this case with erect light or blackish simple trichomes to 0.5 mm restricted to the proximal third of its length, the abaxial face dull and uniformly covered with light simple erect or curly trichomes to 0.5 mm, these very dense and concealing the surface of younger blades, sparser and revealing the surface in older blades; glandular dots 6 to 10/mm², about 0.1 mm in diameter, visible against light and sometimes blackish and moderately sunken in the adaxial face; apex rounded or emarginate; base cuneate, widely cuneate or rounded; midvein adaxially plane or very slightly raised in a fine line most visible in the distal half, abaxially markedly prominent and more or less darker than the surface, sometimes the trichomes falling and then with a more marked contrast; lateral veins 8 to 14 at each side, leaving the midvein at 70–80°, visible and raised on both sides, sometimes intermixed with visible secondary lateral veins of smaller gauge; marginal vein 0.8–2.5 mm from the strongly revolute margin. Inflorescences axillary or terminal, paniculiform, these sometimes arising serially at the axils of elliptic bracts 7–10 × 4–6 mm and then simulating a more ramified panicle; main axis 30–40 × 0.8–1 mm (peduncle 20–30 mm), densely covered with ascending simple grey trichomes to 1 mm, mostly with two branches 7–8 × 1 mm, crowned by three to five sessile flowers; bracts linear, 3–4.5 × 1 mm, with trichomes to 0.5 mm, these falling abaxially; bracteoles linear, to 3 × 1 mm, deciduous after anthesis; flower buds globose or slightly obovate, to 4 × 3–3.5 mm, densely covered with white or grey trichomes to 0.8 mm, these more concentrated on the ovary, sometimes falling from the abaxial side of the calyx lobes and these then darker than the rest of the bud; globe of petals mostly concealed by the calyx lobes before anthesis; calyx lobes four or five, not connate in bud, slightly unequal, ovate to widely ovate, 1.2–1.8 × 1.8–2.5 mm, pilose on both sides, a little less so abaxially; petals obovate, 3.5–5 × 3 mm, adaxially glabrous and with scattered simple white trichomes in the central portion abaxially; stamens not counted, 4–5 mm, the anthers globose, to 0.2 mm in diameter, eglandular; staminal ring to 2 mm in diameter, glabrous; calyx tube to 1 mm deep, glabrous; style 6–7 mm, the stigma glabrous, finely papillose; ovary with three locules and two basally attached ovules per locule. Fruits unknown.
Distribution, habitat and phenology:—This species is presently known from the two neighboring municipalities of Pacaraima and Uiramutã, in the northern portion of the state of Roraima, where it was collected in rocky soils. Flowers were collected in May.
Conservation:—This species is known from two collections from the municipalities of Pacaraima and Uiramutã; both municipalities encompass an area of about 16,000 km ² (IBGE 2015b) and from which there are known 475 and 540 botanical gatherings respectively (CRIA 2015), resulting in a density of 0.06 collection/km², indicative of scarce collection efforts. Since there is no additional information regarding the environment of this species and the collections do not bear goegraphical coordinates, it would be adequate presently scoring it as DD (Data Deficient) according to IUCN conservation criteria (IUCN 2001).
Affinities:—The overall aspect of this species is reminiscent of the Venezuelan Myrcia porphyrea McVaugh (for description see McVaugh 1969: 119; image: MICH 1109562!) and Myrcia crispa McVaugh (for description see McVaugh 1969: 130; image: MICH 1109527!), with which it is compared in the diagnosis.
Etymology:—The epithet is allusive to the collection place of the type specimen, Cachoeira dos Macacos.
Paratype:— BRAZIL. Roraima: mun. Uiramutã, 17 April 2007, J. Batista 1601 (INPA!, MIRR!).
description: Published as part of Sobral, Marcos, Souza, Maria Anália Duarte De & Luize, Bruno G., 2015, Three new northern Brazilian Myrtaceae, pp. 165-173 in Phytotaxa 219 (2) on pages 170-172, DOI: 10.11646/phytotaxa.219.2.6, http://zenodo.org/record/13637020