Myrceugenia oreades F.C.S.Vieira & H.Lisboa, 2025

Vieira, Fábio Christiano Speck, Fonseca, Heitor Lisboa Da, Meireles, Leonardo Dias, Zavatin, Danilo Alvarenga, Sano, Paulo Takeo & Lucas, Eve, 2025, Amidst the cloud forests of the mountains, three new species of Brazilian Myrceugenia (Myrtaceae) are described, Phytotaxa 691 (2), pp. 201-210 : 207-209

Myrceugenia oreades F.C.S.Vieira & H.Lisboa , sp. nov.

TYPE:— BRAZIL. São Paulo: Campos do Jordão, São José dos Alpes, 22º42’34”S, 45º26’29”W, 07 July 2024, F.C.S. Vieira & H.Lisboa 3633 (holotype USP!, isotypes JOI!) .

Figures 2 , 5 .

Diagnosis:— The species resembles Myrceugenia alpigena (DC.) Landrum (in Landrum 1980: 372; basionym: Eugenia alpigena De Candolle [1828: 265] ; type image: M 0136822); however, the latter is characterized by dibrachiate trichomes, approximately 10 secondary veins at each side, and 4–12 ovules per locule. In contrast, M. oreades possesses both simple and dibrachiate trichomes, 5–7 pairs of secondary veins, and 2–4 ovules per locule.

Description:— Shrubs 1–1.5 m, bark rough, gray to beige in color, light brown on young branches; young branches cylindrical; trichomes adpressed, simple and dibrachiate, the dibrachiate ones with a short, triangular central axis and short symmetrical arms, sericeous–flaky on young branches, light brown, shedding over time on petioles, lighter and more sparse on the abaxial leaves surface. Leaves with cylindrical petioles, slightly furrowed on the adaxial side, 1.2– 1.8 × 0.6–0.8 mm; lamina chartaceous, ovate–elliptical. 14–19 × 4–8 mm, about 2.7 times as long as wide, light green on the abaxial surface and dark green on the adaxial surface, few translucent glands protruding on the abaxial surface, number of translucent glands per reticulum, visible under a magnifying glass, is unclear due to the indistinct reticulum; base cuneate; apex rounded, with a small mucron visible under magnification, margin revolute; primary vein slightly protruding on the abaxial surface, and lightly furrowed on the adaxial side; secondary veins leaving the midvein at an angle of approximately 45º, inconspicuous to the naked eye and barely noticeable even under magnification, around 5–7 pairs on the abaxial surface, not visible on the adaxial surface; marginal vein inconspicuous. Flowers solitary, bracts absent; peduncles covered by simple and dibrachiate trichomes, beige to brown, 1.2 × 0.5 mm; bracteoles narrow-triangular, 2.2–2.4 × 0.7–1 mm, internally weakly concave and glabrous, externally covered by simple and dibrachiate beige trichomes, with a prominent rib, free at the base, inserted into the base of the ovary, reaching the median portion of the flower bud; flower buds globose with visible petals; sepals rounded, 1.8–2 × 1.3–1.6 mm, with an obtuse apex, covered with brown to beige trichomes on the external surface and tufts of trichomes at the apex, concave, internally greenish with scattered hyaline trichomes; petals orbicular, 3.4–4 × 2.4–2.8 mm, glabrous, mostly white, greenish in the center where translucent glands appear; stamens semi-curved in the bud, 2.8 × 0.1 mm, 69–88; ovary bilocular, with 2–4 ovules per locule, 4–8 ovules in total; style 3.1 × 0.2 mm, covered with sparse simple hyaline trichomes, stigma punctate; fruits not seen.

Distribution, habitat and phenology:—The species has been documented exclusively along the boundary between the municipalities of Campos do Jordão and Pindamonhangaba in the state of São Paulo, specifically in high-altitude grasslands at approximately 1800 meters of elevation. Observations of the species with flowers occurred between July and November.

Conservation status:—All registered sampling specimens are situated in regions adjacent to the Campos do Jordão State Park; the species has not yet been documented within the protected area. The analysis conducted using GEOCAT indicates that the species should be classified as Critically Endangered based on its extent of occurrence, (EOO= 0.0 km²), and by area of occupation (AOO = 4 km ²). Consequently, we assert that urgent conservation measures for the species must be implemented.

Affinities:—The species exhibits a superficial resemblance to Myrceugenia alpigena (for description see Landrum 1981b); however, based on the criteria established in this study, M. alpigena , is a species that is widely distributed in the southeast and south of Brazil, and it is characterized by a maximum of 5–7 secondary veins and leaf proportions of 1.6/1. However, M. oreades is endemic to the mountains located on the borders of the Campos do Jordão and Pindamonhangaba municipalities, and typically exhibits 10 pairs of secondary veins, and leaf proportions of 2–5/1, in addition to the distinguishing features outlined in the diagnosis.

Etymology:—The specific epithet is derived from the Oreades nymphs, who were believed to inhabit and protect the mountains of ancient Greece. This concept also relates to Martius (1840) interpretation of Brazilian mountainous phytogeographical regions.

Paratypes:— BRAZIL. São Paulo: Campos do Jordão, São José dos Alpes, Parque Estadual de Campos do Jordão , Estrada de terra “Caminho de Aparecida”, próxima à entrada do parque. Beira da estrada, lado direito. 28 August 2012, C.L. Silva-Luz 959 ( USP!) ; São Paulo: Pindamonhangaba, 05 November 2022, N. Ivanauskas 7296 ( SPSF *) .

Figures

FIGURE 2. Distribution map of Myrceugenia nebulosa and M. oreades.

FIGURE 5. Myrceugenia oreades. A. Branch with flowers at the end of anthesis. B. Stem. C. The upper surface of the leaf. D. The underside of the leaf. E–F. Flower bud. G. Flower at anthesis. G. Flower and bracteoles. (Isotype from Vieira & H.Lisboa 3633).