Eugenia asema I.G.Costa & M.C.Souza, sp. nov.
Creators: name: Sobral, Marcos
name: Costa, Idimá G.
name: Souza, Marcelo C.
name: Zorzanelli, João Paulo F.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Myrtaceae
Eugenia
Eugenia asema

description: 1. Eugenia asema Sobral, I.G.Costa & M.C.Souza, sp. nov.
Type:— BRAZIL. Rio de Janeiro: Cardoso Moreira, localidade de Vinhático, sítio do dr. Márcio, 21 February 2014, I.G. Costa 375 (holotype RB!, isotype HUFSJ!).
Figure 1.
Diagnosis:—This species is apparently related to Eugenia subavenia, from which it is distinguished by its glabrous twigs (versus pubescent in E. subavenia), blades with midvein adaxially plane or raised (vs. sulcate), drying dark brown or blackish, shining at least adaxially (vs. drying dull dark green), lateral veins visible and moderately raised adaxially (vs. plane and scarcely visible), shorter bracteoles (to 1 × 0.7 vs. to 2 × 1 mm), glabrous flowers (vs. pilose at least on the ovary) with shorter, glabrous calyx lobes (to 2 mm vs. pilose, to 3 mm) and apparently smaller fruits (to 10 mm —although immature—vs. to 25 mm). It may also resemble E. umbellata, from which it differs by its leaves with proportionally shorter petioles (petioles to 4 mm, mostly 10% of the blade’s length vs. 8–13 mm, 10–15% of the blade’s length), shorter blades (to 53 mm vs. 60–100 mm), with midvein plane or raised (vs. impressed), pedicels longer than the flower buds (pedicels to 10 mm and buds to 5 mm vs. pedicels to 8 mm and buds 6–8 mm), and smaller fruits (to 8 × 6 mm vs. to 20 × 15 mm).
Description:—Shrubs to trees 2– 4 m. Plants glabrous except for occasional cilia to 0.1 mm in the calyx lobes and petals. Twigs light brown or grey, longitudinally finely striate, sometimes exfoliating in longitudinal papery stripes, the internodes 16–25 × 1–2 mm. Leaves with petioles 3–4 × 1–1.2 mm, adaxially applanate, usually darker than the blades when dry; blades elliptic or ovate, 30–53 × 12–29 mm, 1.4–2.5 times longer than wide, somewhat undulate when dry, discolorous, dark green and sometimes shining adaxially, lighter and dull abaxially; glandular dots visible and moderately raised on both faces, darker than the surface abaxially, up to 15/mm², of distinct sizes, the larger more scattered and 0.1 mm in diameter or even larger; apex acute or widely acuminate to 5 mm; base cuneate, sometimes decurrent on the petiole; midvein plane or moderately raised, rarely biconvex, adaxially, and usually visibly raised abaxially; lateral veins 6 to 10 at each side, raised on both sides, a little more so abaxially, sometimes secondary lateral veins also visible and about the same gauge; marginal veins one or two, the inner one more or less arched between the lateral ones, respectively 0.7–2 mm and about 0.5 mm from the plane margin. Inflorescences axillary or ramiflorous, umbelliform or racemiform, the axis absent or 1–3 × 0.7–1 mm, with two to four flowers; bracts elliptic, to 0.8 × 0.5 mm, persisting at anthesis; pedicels 6–10 × 0.4–0.6 mm, somewhat applanate; bracteoles triangular or elliptic, 0.6–1 × 0.7–1 mm, persisting even in fruits; flower buds globose or obovate, 4–5 × 3–4.5 mm, the ovary markedly distinct from the calyx lobes, these visible smaller than the evident globe of the petals; calyx lobes four, markedly glandular, widely elliptic, more or less unequal between them, the external ones 1–1.5 × 2 mm, the internal ones 1.5–2 × 2–2.2 mm; petals four, elliptic, white, 4.5–6.5 × 5 mm, markedly glandular even in bud; stamens about 160, 6–8 mm, the anthers elliptic, to 0.7 × 0.3 mm, with one apical gland; staminal ring to 2 mm in diameter; calyx tube absent; style 8–10 mm, the stigma punctiform and minutely papillose; ovary with two locules and up to fifteen ovules per locule. Fruits elliptic, 7–8 × 5.5–6 mm, immature, crowned by the erect calyx lobes; seeds very immature, not examined.
Distribution, habitat and phenology:—Collected in coastal rainforests (“Mata Atlântica”) in the municipalities of Cardoso Moreira, Maricá and Rio de Janeiro, in the northern and southern-central parts of the state of Rio de Janeiro. Flowers were collected from December to February and fruits in August.
Conservation:—The municipalities where E. asema was collected are about at least 200 km apart (IBGE 2017b), and there is no accurate information either regarding the environmental conditions of the collection sites or population size. Considering this, we score this species as DD (Data Deficient) according to IUCN conservation criteria (IUCN 2001).
Affinities:— Eugenia asema is apparently related to E. subavenia O. Berg (1857 –1859: 571; type image: LE 00007510), a species relatively common along southeastern Brazilian coastal rainforest; it is also reminiscent of E. umbellata Sprengel (1821: 169; type image: MO 2527408), a southeastern and southern Brazilian species. Eugenia asema is compared with both species in the diagnosis. Due to the inflorescence structure, this species clearly belong to section Umbellatae O.Berg (Berg 1855 –1856: 204; see the phylogenetic scheme proposed by Mazine et al. 2016).
Etymology:—The epithet is derived from the Greek words for “without mark”, due to the scarcity of exclusive characters that distinguish this species from their related ones; in this case, one must rely in a large set of characters to adequately distinguish it.
Paratypes:— BRAZIL. Rio de Janeiro: Cardoso Moreira, mata da Bicuíba, sítio de Wanderley, 24 January 2014, I.G. Costa 339 (HUFSJ!, RB!); Maricá, Ilha Cardosa, 26 August 1993, M.C.L. Ramos & L. Pellens 176 (RB!); Rio de Janeiro, Paquetá, Moreninha, 31 December 1983, J. Cardoso 245 (R!).
description: Published as part of Sobral, Marcos, Costa, Idimá G., Souza, Marcelo C. & Zorzanelli, João Paulo F., 2017, Five new species and one new combination in Brazilian Myrtaceae, pp. 233-244 in Phytotaxa 307 (4) on page 234, DOI: 10.11646/phytotaxa.307.4.1, http://zenodo.org/record/13686491