Eugenia circumdata Mazine & Sobral, 2018

Mazine, Fiorella F., Sobral, Marcos & Valdemarin, Karinne Sampaio, 2018, A new species of Eugenia (Myrtaceae) from Rio de Janeiro State, Brazil, Phytotaxa 343 (2), pp. 160-166 : 161-165

Eugenia circumdata Mazine & Sobral , sp. nov. (Figures 1–3).

Type:— BRAZIL. Rio de Janeiro: Rio das Ostras, Reserva Biológica União, baixada, trilha 1, 18 November 1997, fl., P. P. Oliveira 51 A (holotype SP!; isotype BHCB!) .

Diagnosis:— Eugenia circumdata is related to Eugenia myrobalana De Candolle (1828: 277) by its inflorescence structure, bracteoles orbiculate or obovate, concave, surrounding the flower bud, and deciduous at anthesis, but differs from it by its leaf blades 14–17.5 cm long (vs. 23–33 cm), indistinct glandular dots (vs. dark glandular dots), inflorescences with tomentose indumentum and 2–4 pairs of flowers (vs. pubescent and with 6–8 pairs), axillary (vs. flowers on leafless nodes), pedicels 4–7 mm long (vs. 12–25 mm), flower buds globose (vs. ellipsoid) and fruits, when young, depressed-ellipsoid to globose (vs. ellipsoid).

(Habit and height unregistered). Twigs terete, sometimes slightly longitudinally striate, moderately tomentose, glabrescent, gray or light brown when dry, the internodes 50–95 × 3–7 mm. Leaves with petioles canaliculated adaxially, 11.5–18 × 1.5–2 mm, moderately tomentose, glabrescent; blades elliptic or wide elliptic, 14–17.5 × 7.5– 10.5 cm, chartaceous, slightly concolorous, very sparsely puberulent adaxially, sparsely tomentose abaxially, hairs dichotomous; glandular dots almost indistinct on both sides; apex obtuse, rarely rounded; base obtuse or attenuate; midvein slightly sulcate adaxially, strongly raised abaxially, very sparsely puberulent adaxially, moderately tomentose abaxially; lateral veins 8–12 at each side, slightly prominent adaxially, raised abaxially, first pair confluent with the marginal vein; marginal veins two, the innermost 4.5–10 mm, the outermost 0.9–2.5 mm from the margin, the margin itself plane. Inflorescences axillary, racemiform reduced to fascicles, 2–4 pairs of flowers; peduncle sessile or up to 2 mm long; rachis 2–15.5 mm long, densely tomentose, hairs brown-yellowish; bracts ovate, ca. 1.5 × 1.5 mm, densely tomentose, deciduous before anthesis; pedicels terete, 4–5 mm long, tomentose; bracteoles orbiculate or obovate, 5–6 × 5–6 mm, concave, surrounding the flower bud, apex obtuse to rounded, tomentose, deciduous at anthesis. Flower buds globose, 4–5 mm diam., hypanthium smooth, tomentose; calyx lobes four, in two unequal pairs, the outermost wide ovate to very wide ovate, 4–5 × 3–4 mm, the innermost wide ovate to very wide ovate, 3.5–4 × 3–4 mm, glabrous internally and tomentose externally; petals four, obovate, 5–6 × 4.5–5 mm, glabrous, glandular dots visible and raised externally; stamens with filaments 3–4 mm long, the anthers globose, 0.5 mm in diam.; staminal ring circular to 5.5 mm in diam., pubescent; style 6–7 mm long, the stigma punctiform; ovary with two locules and ca. 14 ovules per locule. Fruits young depressed-ellipsoid to globose, 10–13 × 12–15 mm, tomentose, smooth surface.

Distribution and habitat: —This species is only known from “Reserva Biológica União”, in the municipality of Rio das Ostras in the Atlantic forest Domain. Habitats on lowland and sub-montane forests are referred on the labels respectively as “baixada” and “morro” (Figure 4).

Phenology: — Eugenia circumdata was collected with flowers in November and December, and with young fruits in December.

Etymology: —The specific epithet is derived from the Latin word for “encircled” or “surrounded”, in allusion to the bracteoles surrounding the flower buds.

Conservation: — Eugenia circumdata has been collected only in the municipality of Rio das Ostras within a federal protected area (Reserva Biológica União). It is known only from four specimens, the most recent collected almost twenty years ago ( CRIA 2017, Silva et al. 2017). Even though the species occurs inside a conservation area, its low extent of occurrence (EOO= 12.84 km ²) and the absence of recent collections may indicate its rareness. Considering these, it is herein scored as Critically Endangered, CRB1ab(i,iii), according to IUCN conservation criteria ( IUCN 2012).

FIGURE 1. Eugenia circumdata Mazine & Sobral. a. Branch with flower. b. Flower bud detailed. c. Ovary in transversal section. (P.P. Oliveira 51A [BHCB]) by Maria Alice Rezende.

Affinities: — Eugenia circumdata can be assigned to Eugenia section Umbellatae O. Berg (1855 –1856: 204) considering the inflorescence structure, and according to the infrageneric key presented by Mazine et al. (2016). Just one more species is known by concave bracteoles surrounding the flower bud in Eugenia section Umbellatae , E. myrobalana . It’s important to mention that are other species with concave bracteoles but just surrounding the hypanthium, not the entire bud, in the section, as E. crassa Sobral (2010: 338) and E. goiapabana Sobral & Mazine (2010: 348) . Due to these features, Eugenia circumdata resembles E. myrobalana which occurs in northern Brazil and Peru ( McVaugh 1958, Govaerts et al. 2017); the comparison between these species was presented in the diagnosis.

FIGURE 2. Holotype of Eugenia circumdata .

FIGURE 3. Paratype of Eugenia circumdata with young fruits. (P.P. Oliveira 51N [BHCB]).

FIGURE 4. Geographical distribution of Eugenia circumdata based on herbarium specimens.

Paratypes:— BRAZIL. Rio de Janeiro: Rio das Ostras, Reserva Biológica União, morro, 11 December 1999, fl., P. P. Oliveira 267H (BHCB!, SP!). Rio das Ostras, Reserva Biológica União, baixada, 13 December 2000, fr., P. P. Oliveira 51N (BHCB!). Rio das Ostras, Reserva Biológica União, baixada, trilha 1, 10 November 1997, fl., P. P. Oliveira 51B (BHCB!, SP!, SPF!).