Eugenia trichogyna 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 trichogyna

description: 2. Eugenia trichogyna Sobral, I.G.Costa & M.C.Souza, sp. nov.
Type:— BRAZIL. Rio de Janeiro: Italva, Cachoeira do Caboclo, margem do rio Muriaé, 3 March 2014, I.G. Costa 301 (holotype RB!, isotype HUFSJ!).
Figure 2.
Diagnosis:—This species is apparently related to Eugenia pluriflora, from which it is distinguished through its leaves with shorter petioles (visible mostly abaxially, the proportion blade/petiole length 25–30:1 versus visible on both sides of the leaves, the proportion blade/petiole length 12–15: 1 in E. pluriflora), chartaceous blades, bending easily at touch when dry (vs. coriaceous, not bending when dry), 40–50 mm wide (vs. up to 30 mm wide), with lateral veins weakly raised (vs. markedly raised on both sides), more densely glandular (glands to 0.05 mm in diameter and up to 30/mm², usually better visible under lenses vs. to 0.1 mm and about 10/mm², markedly visible at naked eye especially abaxially), margin plane or slightly revolute (vs. strongly revolute), apex and base rounded (vs. apex widely acute or acute and base cuneate), flowers with calyx lobes with two unequal pairs, the smaller ones to 2 mm (vs. more or less equal between them, ca. 1 mm) and ovary densely covered with white trichomes (vs. glabrous).
Description:—Tree 2– 4 m. Twigs glabrous, light grey, applanate, moderately sulcate longitudinally; internodes 27–45 × 1,8– 2 mm. Leaves with petioles 1.8–3 × 1–1.5 mm, glabrous, adaxially applanate, sometimes visible only abaxially; blades glabrous, chartaceous, elliptic or widely elliptic to obovate, 53–82 × 40–55 mm, 1.3–1.7 times longer than wide, dull light green when dry, concolorous or slightly discolorous, then lighter abaxially; glandular dots about 30/mm², of several sizes, the largest ones to 0.05 mm in diameter, visible and somewhat darker than the surface on both sides; apex rounded; base obtuse or rounded; midvein adaxially plane or finely sulcate, sometimes the proximal half weakly biconvex, abaxially raised; lateral veins 8 to 10 at each side, leaving ther midvein at angles 60–70º, moderately raised on both sides, a little more so abaxially, the blade surface a little undulate along their course, the secondary lateral veins inconspicuous; marginal veins two, the inner one sometimes arched between the lateral veins and the outer one more continuous, respectively 2–4 mm and 0.7–1.8 mm from the plane or weakly revolute margin, the margin itself with a yellow girdle 0.1–0.2 mm thick. Inflorescences ramiflorous, with two to six flowers, umbelliform or racemiform, then the axis up to 1.5 × 0.4 mm, with sparse simple trichomes to 0.1 mm; bracts elliptic, to 0.8 × 0.7 mm, glabrous, persisting at anthesis; pedicels 2–3.5 × 0.6 mm, moderately applanate, glabrous or with very scattered trichomes as the axes; bracteoles widely elliptic, 0.7–0.8 × 1–1.3 mm, glabrous, sometimes partially fused at their bases, persisting after anthesis; flower buds not seen; ovary externally densely covered with simple, appressed white trichomes to 0.1 mm, clearly distinct from the glabrous calyx lobes, these four, patent at anthesis, in unequal pairs, the smaller ones widely ovate, 1.5–2 × 1.5–2 mm, the larger ones widely elliptic to oblong, 2.2–3 × 2–2.8 mm; petals, stamens and styles not seen; staminal ring subquadrate, ca. 2 mm wide, with scattered white trichomes to 0.1 mm; calyx tube absent; ovary with two locules and 8 to 10 ovules per locule. Fruits oblate, to 6–7 × 9 mm, yellow, immature in the specimens examined; seed one per fruit, immature, not examined.
Distribution, habitat and phenology:—Presently known only from one location at the municipality of Italva, in the northern portion of the state of Rio de Janeiro, where it was collected along river margins in coastal rainforest; flowers were collected in March and fruits in September.
Conservation:—The municipality of Italva has an area of 293 km ² (IBGE 2016b), from which are known about 160 collections (INCT 2016, JABOT 2017), a small sampling effort (0.5 collection/ km²); since we do not have additional information about the environmental conditions of the collection site, we score this species as DD (Data Deficient) according to IUCN conservation criteria (IUCN 2001).
Affinities:—Apparently related to Eugenia pluriflora De Candolle (1828: 270; type image: M 0171076), a usually highland species from southeastern and southern Brazil, from which it is distinguished through the characters given in the diagnosis. In the same way as E. asema, the inflorescence morphology allows assigning this species to section Umbellatae (see Mazine et al. 2016).
Etymology:—The epithet is derived from the Greek words for “pilose ovary”, alluding to one of the most distinctive features of this species when compared to the related Eugenia pluriflora.
Paratype:— BRAZIL. Rio de Janeiro, mun. Italva, Cachoeira do Caboclo, beira do rio Muriaé, September 2013, I.G. Costa 254 (HUFSJ!, RB!).
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 236, DOI: 10.11646/phytotaxa.307.4.1, http://zenodo.org/record/13686491