Myrceugenia joinvillensis F.C.S.Vieira, 2020

Vieira, Fábio Christiano Speck, 2020, A new species of Myrceugenia (Myrtaceae) from Southern Brazil, Phytotaxa 435 (2), pp. 208-212 : 208-211

Myrceugenia joinvillensis F.C.S.Vieira , sp. nov. ( Figures 1–3 ).

Type:— BRAZIL. Santa Catarina: Joinville, Morro Mutucas , Floresta Ombrófila Densa , face Sul , ca. 400 m elev., 16 November 2017, fl., fr., F. C. S.Vieira 2784 (holotype JOI!; isotypes HUFSJ!, HBR!, MBM!) .

Myrceugenia joinvillensis is morphologically related to Myrceugenia reitzii D. Legrand (1961: 305) , from which it is distinguished by its axillary flowers and linear to narrowly ovate calyx lobes (versus bracteate shoots and broadly ovate to hemi-orbicular calyx lobes in M. reitzii ). It may also resemble Myrceugenia pilotantha (Kiaersk.) Landrum (1980: 374; basionym: Eugenia pilotantha Kiaerskou, 1893: 169 ), but its petioles are 3.5–5 mm (vs. 2–8 mm in M. pilotantha ) and blades are 55–80 mm wide (vs. less than 40 mm wide), with widely rounded to cordiform base (vs. cuneate), and simple trichomes (vs. a mixture of simple and asymmetrically dibrachiate). Additionally, it is also morphologically alike Myrceugenia venosa D. Legrand (1957: 323) but differs by its simple trichomes (vs. symmetrically dibrachiate), blades with widely rounded to cordiform base (vs. cuneate to barely acuminate) and linear to narrowly ovate calyx lobes to 10–12mm (vs. ovate to triangular to 2.5–5.5mm).

Shrub or small tree 1.5–3 m; bark light brown until grey; trichomes simple, brown-reddish, twigs densely pubescent when young, turning glabrescent with age, flattened at the nodes first, becoming terete with age. Leaves with petioles, petiolate 3.5–5 × 2.5–4.5 mm; blades elliptic to ovate, chartaceous, discolorous, drying dark grey-green or lighter grey-green above, lighter grey-green or yellow-green below, 80–130 × 55–80 mm, 1.4–1.6 times longer than wide; apex mucronate, 3–5 × 1 mm; base widely rounded to cordiform; adaxial surface predominantly glabrous except for trichomes along the midvein and lateral veins; abaxial surface sparsely to densely pubescent along the midvein and lateral veins; midvein adaxially impressed and abaxially prominent; lateral veins 10–15 pairs, adaxially impressed and abaxially prominent; marginal veins two, the inner one to 5–8 mm and the outer one to 1 mm from the plane margin. Flowers axillary, solitary or up to 3 superposed in a row, pedicels absent or to 10 × 1.5–2 mm, densely pubescent, bracteoles linear to narrowly triangular, 5–6 × 1 mm, concave, densely pubescent without, sparsely pubescent within; calyx lobes 4, narrowly ovate, 10–12 × 3 mm, the apex linear in 2–3 mm, concave, densely pubescent without, sparsely pubescent within; petals 4 orbicular, 3–4 × 3–4 mm, concave, densely pubescent without, glabrous within, ciliated; stamens 100–150, ca. 6 mm long; style ca. 6 mm long, stigma punctiform, with trichomes in the base; ovary 3-locular, 9–12 ovules per locule. Fruits oblong-elliptic, 20–25 × 10–15 mm, brownish at maturity, pubescent, calyx lobes persistent; seeds 5–6, testa membranous, embryo with two foliaceous cotyledons encircled by a well-developed hypocotyl.

Distribution and Habitat:— Myrceugenia joinvillensis is known only on the edge of the mountains in Atlantic Forest, approximately 400–700 m elev. in the Serra do Mar in Southern Brazilian state of Santa Catarina, in the municipalities of Joinville and Schroeder ( Figure 3).

Phenology:— Myrceugenia joinvillensis was registered with flowers buds and fruits from June to April.

Conservation status:—With the geographic coordinates of the collections and the places where the species was observed, and the use of Geospatial Conservation Assesment Tool (GeoCAT 2019), this species presents the extent of occurrence (EOO = 3.089 km ²), and area of occupancy (AOO = 12 km ²), also the observed population size of this species is estimated to number fewer than 50 mature individuals, indicates that Myrceugenia joinvillensis should be categorized as CR (critically endangered), according to the conservation criteria of IUCN (2017).

Etymology:—The specific epithet alludes to the Brazilian municipality of Joinville, where this species was collected for the first time.

Paratypes:— BRAZIL. Santa Catarina, Joinville, Morro Mutucas , 03 February 2009, fl., F. C. S. Vieira 2129 ( ASE!, HUCS!, JOI!) ; ibid., Morro Mutucas , 20 April 2010, fl., W. S. Mancinelli 1208 ( JOI!) ; ibid., Morro Mutucas , 11 October 2017, fl., F. C. S. Vieira 2783 ( JOI!) ; ibid., Morro Mutucas, 16 November 2017, fl., F. C. S. Vieira 2785 ( JOI!, HBR!). Schroeder, Barragem 8° Salto, 26 June 2018, fr., A. Kassner-Filho 2909 ( FURB; RB, image!) .

Figures

FIGURE 1. Myrceugenia joinvillensis. A—Fruits, seeds and embryo, B—Holotype, C—Trilocular ovary (A–C from holotype).

FIGURE 2. Myrceugenia joinvillensis. A—Mucronate apex (adaxial surface), B—Mucronate apex (abaxial surface), C—Flowers in leaf axiles, D—Bud, E and F—Bracteoles, G—Calyx-lobes, H—Petals, I—Style, J—Stamens (A–B, E–F and J from holotype; C–D and G–I from Vieira 2785).