Myrcia basicordata Sobral, 2013

Sobral, Marcos, 2013, Eight New Atlantic Rainforest Species and Nomenclatural Notes in Brazilian Myrtaceae, Phytotaxa 135 (1), pp. 43-61 : 54

1.6. Myrcia basicordata Sobral , sp. nov.

Type: BRAZIL. Espírito Santo: mun. Santa Teresa, Santo Antônio, Terreno do Bosa (Chapada) , 14 Jan. 1999, L. Kollmann & E. Bausen 1568 (holotype MBML ; isotype HUFSJ ).

Figure 6 .

This species is related to Myrcia pubescens , differing by its glabrous, markedly applanate twigs and glabrous, sessile leaves with a cordate base.

Trees 2– 12 m. Twigs applanate, with simple grey trichomes to 0.2 mm at the apical gems, these black when dry; internodes 10–30 × 5–8 mm, with transverse interpetiolar scars, these with linear or acicular colleters 2–3 × 0.2 mm. Leaves sessile or with petioles to 1 × 3 mm; blades elliptic or ovate-elliptic, 70–125 × 40–60 mm, 1.5–1.8 times longer than wide, glabrous, sometimes discolorous when dry, with 5 to 10 glandular dots per square milimeter, these about 0.1 mm in diameter, visible abaxially; apex rounded or acute; base rounded or cordiform; midvein sometimes darker than the rest of the blade, adaxially sulcate and abaxially prominent; lateral veins 8 to 11 on each side, slightly to markedly prominent on both sides, leaving the midvein at angles 80–90 degrees; marginal veins two, 3–4.5 mm and 0.8–1.6 mm from the margin respectively, the margin itself revolute. Inflorescences axillary, paniculiform, with 7 to 20 flowers, the main axis 65–85 × 3 mm, with one or two branchings; pedicels absent or up to 1 × 1 mm; bracteoles not seen, probably deciduous before anthesis; flower buds obovate, to 6 × 4 mm, the ovary densely covered by grey appressed trichomes to 0.1 mm, markedly distinct from the five calyx lobes, these glabrous or much more sparsely pilose, hemispheric and somewhat unequal in size, 2.3–3 × 3–4 mm; petals and stamens not seen; staminal ring 3–4 mm in diameter; style not seen; calyx tube up to 2 mm deep; ovary with two locules and two ovules per locule. Fruits globose to slightly oblate, 10–12 × 14–15 mm, unripe in the examined specimens; seeds one to two per fruit, immature, with an undeveloped embryo, this with a visible hypocotyl and two distinct foliaceous cotyledons.

Distribution, habitat and phenology:—collected until now only in the municipality of Santa Teresa, in the highlands of the southeastern Brazilian state of Espírito Santo, where it grows along the forest border, at 650– 850 m elev.; flowers were collected in January and March, and fruits in March, April and September.

Conservation:—the municipality of Santa Teresa has been intensely surveyed, with a collection density of about 40 collections / km 2 (see discussion under Calyptranthes santalucia ); nevertheless, M. basicordata is known from only four gatherings, which is suggestive of its rarity. This information, together with relatively recent estimates that only 18% of the original vegetation of Santa Teresa remain ( Mendes & Padovan 2000) fits IUCN criteria B1 ab(iii) for the Endangered (EN) category (IUCN 2001), since the extension area of the species is smaller than 5000 km 2 (criterion B1), and it grows in a severely fragmented area (criterion a) which presents a constant decline of extent (criterion b(iii)).

Affinities:—this species is apparently related to Myrcia pubescens De Candolle (for description see De Candolle 1828 or Berg 1857–1859), of which it can be distinguished by the characters in the following couplet:

1. Twigs cylindrical or slightly applanate, pilose; leaves with petioles at least 3 mm long; blades pilose at least abaxially, the base mostly rounded, never cordate ................................................................................... Myrcia pubescens

—. Twigs markedly applanate and glabrous; leaves sessile or with petioles to 1 mm; blades glabrous, the base mostly cordate............................................................................................................................................ Myrcia basicordata

Etymology:—the epithet is allusive to the cordate bases of the leaves of this species.

Paratypes:— BRAZIL. Espírito Santo: mun. Santa Teresa, Santo Antônio, terreno do Boza , 9 Mar. 1999, L. Kollmann et al. 2058 ( BHCB, MBML); idem, 27 Apr. 1999, L. Kollmann et al. 2521 ( BHCB, MBML); Estação Biológica de Santa Lúcia , 30 Sept. 1999, Demuner, E. Bausen & W. Pizziolo 75 ( BHCB, MBML); idem, Vargem Alta , 28 Jan. 1986, W. Boone 1062 ( HUFSJ, MBML, RB) .

Figures

FIGURE 6. Myrcia basicordata—isotype at HUFSJ (scale: 50 mm); insert: inflorescence from Boone 1062 (scale: 10 mm).