Eugenia mimetica Sobral & M. C. Souza 2018, sp. nov.
Creators: name: Sobral, Marcos
name: Souza, Marcelo Costa
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Myrtaceae
Eugenia
Eugenia mimetica

description: 1. Eugenia mimetica Sobral & M.C.Souza, sp. nov.
Type:— BRAZIL. Rio de Janeiro: [Resende], Itatiaia, Parque Nacional de Itatiaia, Lago Azul, margem do rio Campo Belo, 18 February 2003, S.J. Silva Neto et al. 1797 (holotype RB!, isotypes K, MBM, NY). Figure 1.
Diagnosis:—This species is morphologically related to Eugenia praeterita McVaugh (1963: 450), from which it differs by its blades 62–95 × 22–29 mm, 2.5–3.5 times longer than wide (versus 100–140 × 40–60 mm, 2.3–2.5 times longer than wide in E. praeterita), inflorescences with axes to 1–2 mm (vs. to 10–15 mm) with 2 to 4 flowers (vs. 4 to 10 flowers), pedicels 5–9 mm (vs. 2–3 mm) and ovaries with 4 to 6 ovules per locule (vs. 8 to 10). It may also remind Eugenia pisiformis Cambessèdes (1832 –1833: 356), but the abaxial side of adult blades is densely and uniformly beset with rufescent erect or curled trichomes (versus indumentum absent or sericeous with appressed trichomes in E. pisiformis) and its flowers have calyx lobes in two unequal pairs (vs. more or less the same size); it also vegetatively resembles E. macrosperma De Candolle (1828: 277) due to its indumentum, but differs by its inflorescences 1–2 mm (vs. 5–10 mm in E. macrosperma) and pedicels 5–9 mm (vs. 1–3 mm).
Description:—Tree 3.5– 6 m. Twigs grey, sometimes with simple rufescent trichomes when young, these falling with age. Leaves opposite, with petioles 6–7 × 1 mm, pilose as the twigs or glabrescent, semiterete, adaxially sulcate, blackish when dry; blades narrowly elliptic, 62–95 × 22–29 mm, 2.5–3.5 times longer than wide, markedly discolorous when dry, dull dark green adaxially and light brown abaxially, the adaxial surface with scattered simple rufescent trichomes to 0.1 mm, these usually more dense along the primary vein and becoming more scattered with age, the abaxial surface densely and, except along the primary vein, uniformly covered with simple erect or slightly curled rufescent trichomes to 0.1 mm, these usually persisting with age; glandular dots occasionally visible abaxially, more easily viewed when backlit, about 30/mm² and smaller than 0.5 mm in diameter; base acute; apex bluntly acuminate, the acumen 6–9 mm, sometimes slightly recurved; midvein adaxially sulcate and abaxially markedly raised, rufescent and usually darker than the surface and more densely pilose than it; secondary veins 10 to 15 at each side, leaving the primary vein at angles about 60°, merely perceptible adaxially, visible and raised abaxially; higher order venation usually not perceptible; intramarginal veins two, the inner one about the same gauge of the secondary veins, 2–2.5 mm from the margin, the outer one somewhat thinner, 0.5–0.9 mm from the slightly revolute margin. Inflorescences axillary, racemiform or fasciculiform, with 2 to 4 flowers, the axis 1–2 × 2 mm, with rufescent trichomes as the twigs; bracts triangular, ca. 1.5 × 1 mm, with scattered trichomes, persisting after anthesis; pedicels 5–9 × 1–1.3 mm, applanate, densely beset with erect or ascending rufescent trichomes to 0.1 mm; bracteoles widely elliptic or widely triangular, 1.2–1.8 × 1.5–2 mm, with scattered rufescent trichomes abaxially, connate at their basal portion, persisting at anthesis; flower buds globose, ca. 5 × 5 mm, covered with rufescent trichomes, the hypanthium 1–1.5 mm, more densely pilose than the calyx; calyx lobes 4, adaxially glabrescent, abaxially pilose, in two pairs unequal in size, the outer one widely elliptic, 2–2.2 × 1.2–2.5 mm, the inner one elliptic, 3–3.1 × 2–3 mm; petals 4, elliptic, 5–6 × 4 mm, sparsely glandulose and ciliate; stamens with filaments to 5 mm and anthers elliptic, to 0.8 × 0.3 mm, apparently eglandular; staminal ring subquadrate, to 3 mm wide and 0.7 mm thick, with scattered whitish trichomes to 0.2 mm; hypanthium tube absent; style glabrous, to 6 mm, the stigma punctiform; ovary with two glabrous locules and 4 to 6 ovules per locule. Fruits not seen.
Distribution, habitat and phenology:—This species was collected in rainforests from the Itatiaia National Park, where it probably grows in riparian forests (according to label data); flowers were collected in January and February.
Conservation:— Eugenia mimetica is known from three collections from the Itatiaia National Park, in the state of Rio de Janeiro. Although the collections are nor georeferenced (the coordinates in the paratype Carrara et al. 20 indeed describe the limits of the park, not the collection site), it is possible to know that Lago Azul is in the same region as “lote 17” in the southwestern portion of the park, in the municipality of Resende (see ICMBIO 2013: 31, 35, 37–38), and that the extent of occurrence (EOO) of this species is probably smaller than 100 km ². Although all specimens were collected inside a protected area, according to Itatiaia Park zonation (ICMBIO 2013) the area known as “lote 17” is located in zones which are allowed to suffer human occupation (“zone of temporary occupation” and “zone of extensive use”; see ICMBIO 2013: 31, 35), and are consequently subject to possible alterations. Nevertheless, since the last specimen of Eugenia mimetica was collected in 2003 and we do not presently have additional information on its population, we suggest scoring it as DD (Data Deficient), according to IUCN criteria.
Affinities:—This species is morphologically related to the Mexican Eugenia praeterita (type image C 10015712) and the Brazilian E. macrosperma (type images M 0171008, M 171009) and E. pisiformis (type image P 01902625), with which it is compared in the diagnosis. Considering the inflorescence morphology, with a central axis scarcely or not developed, this species may be assigned to Eugenia section Umbellatae O. Berg (1855 –1856: 204; see Mazine et al. 2018), as is possibly the case with E. praeterita and E. pisiformis. On the other hand, E. macrosperma, due to its well developed inflorescences, is placed in Eugenia section Racemosae O. Berg (1855 –1856: 278); Eugenia mimetica was compared to this species due to its vegetative indumentum and not inflorescence characters.
Etymology:—The epithet is derived from the Greek word for “mimicking”, alluding to the overall resemblance of this species with some of the genus Myrceugenia O. Berg (1855 –1856: 131); indeed, Eugenia mimetica was labeled under Myrceugenia seriatoramosa (Kiaersk.) D.Legrand & Kausel (in Legrand 1953: 5; basionym: Eugenia seriatoramosa Kiaerskou, 1893: 170) and has been cited under this name in a study of the species of Myrceugenia in the Itatiaia massif (Lima & Guedes-Bruni 2004: 90).
Paratypes:— BRAZIL. Rio de Janeiro: [Resende], Itatiaia, Parque Nacional do Itatiaia, lote 17, 12 February 1943, J.J. Sampaio 1096 (RB); idem, Parque Nacional de Itatiaia, Lago Azul, 22°15’– 22°28’ S, 44°34’– 44°45’ W, 19 January 1995, M.R. Carrara et al. 20 (RB).
description: Published as part of Sobral, Marcos & Souza, Marcelo Costa, 2018, Two new Brazilian Atlantic Forest Eugenia (Myrtaceae), pp. 221-226 in Phytotaxa 382 (2) on pages 222-224, DOI: 10.11646/phytotaxa.382.2.7, http://zenodo.org/record/13724582