Eugenia tingui Sobral, 2018

Sobral, Marcos, Faria, Jair E. Q. & Coutinho, Karoline, 2018, Five new Brazilian species of Eugenia (Myrtaceae), Phytotaxa 347 (1), pp. 59-70 : 65-67

4. Eugenia tingui Sobral , sp. nov.

Type:— BRAZIL. Rio Grande do Norte: Natal, Parque das Dunas , 05 o 48’00” S, 35 o 13’00” W, 9 February 1981, PPD (Projeto Parque Dunas; collectors not cited) 293 ( R 210494! , holotype) . Figure 4 .

Diagnosis:—This species resembles Eugenia stictopetala , differing through its leaves with smaller and wider petioles (petioles to 6 × 2.5 mm versus to 10 × 1.5 mm in E. stictopetala ), smaller and wider blades (to 96 × 80 mm, 1–1.2 times longer than wide vs. to 140 × 65 mm, 2–3 times longer than wide), with up to eight lateral veins (vs. 15) and marginal vein up to 6 mm from the margin (vs. 3 mm), flowers with larger calyx lobes (to 3.5 × 4 mm vs. to 1.3 × 2 mm) in two unequal pairs (vs. equal) and geographical area (coastal scrub forests vs. rocky fields, savannas and rainforests).

Description:—Shrub to 1 m. Twigs glabrous, light grey, somewhat compressed, longitudinally striate; internodes 15–20 × 2–3 mm. Leaves with petioles 5–6 × 2–2.5 mm, glabrous, covered with whitish wax, adaxially applanate; blades widely ovate or widely elliptic, 65–96 × 54–80 mm, 1–1.2 times longer than wide, discolorous when dry, dull green adaxially and brown abaxially; glandular dots visible on both sides, from 10 to 20/mm², mostly smaller than 0.1 mm in diameter intermixed with some larger ones about 0.1 mm in diameter; apex obtuse or rounded; base rounded, slightly attenuate when joining the petiole; midvein adaxially plane, sometimes with a whitish waxy cover as the petioles near the base of the blade, darker than the surface along the rest of its extent, proximally thick and with its gauge diminishing abruptly along the rest of the blade, abaxially markedly salient, darker than the surface and diminishing uniformly in gauge along the blade; lateral veins 5 to 8 at each side, visible and salient on both sides, a little more so abaxially, leaving the midvein at angles 60–70 degrees; secondary lateral veins visible and moderately salient on both sides; marginal veins two, 4–6 and 1–2 mm from the margin, the margin itself revolute and irregularly undulate. Inflorescences ramiflorous, glomeruliform, with an axis to 1 × 1 mm, with two to four flowers; bracts not seen; pedicels 2–3 × 0.8–0.9 mm, glabrous; bracteoles widely elliptic, 1.7–2 × 1.8–2 mm, persisting after anthesis; flower buds globose, 6–7 × 5–6 mm, glabrous; calyx lobes four, widely rounded, unequal, the outer pair 1.5–2.5 × 3 mm, the inner pair 2.5–3.5 × 3.8–4 mm; petals rounded, to 5 mm in diameter; stamens about 100, 6–7 mm, the anthers elliptic or oblong, 0.8–1 × 0.5–0.6 mm, eglandular; staminal ring 3.5–4 mm in diameter, glabrous or with very scattered simple trichomes to 0.1 mm; style to 7 mm, the stigma punctiform; calyx tube absent, the apex of the ovary sometimes slightly elevated; ovary with two glabrous locules and 11 to 13 ovules per locule. Fruits unknown.

Distribution, habitat and phenology:—This species is presently known only from the type collection, gathered more than 30 years ago, from the coastal dunes at Parque das Dunas, a natural reserve in the urban area of the municipality of Natal, in the northeastern Brazilian state of Rio Grande do Norte; it inhabits scrubby coastal forests (“restingas”) along the dunes, and was collected in flowers in February.

Conservation:—The municipality of Natal is relatively well surveyed - it has an area of 167 km 2 and 6,150 exsiccates (data from IBGE 2016 and INCT 2016, respectively), resulting in a high sampling effort of 36 collections/ km 2; considering this, the fact that Eugenia tingui is known from only one specimen may be an indicative of its possible rarity; nevertheless, in the absence of additional information, it is more adequate to score this species as Data Deficient (DD), according to IUCN conservation criteria ( IUCN 2001).

Etymology:—The epithet is derived from the vernacular name of the species registered in the collection label, “tingui de peixe”; according to the label, this plant is toxic to fishes.

Affinities:—This species is morphologically related to Eugenia stictopetala (see additional comments on this species under E. cerradensis ), from which it is distinguished through the characters listed in the diagnosis. Due to its inflorescence morphology, it must be assigned to section Umbellatae , according to the phylogenetic scheme proposed by Mazine et al. (2016). Considering that the last three species described above belong to the Eugenia stictopetala alliance, a brief key for distinguishing them is provided:

1. Leaf blades glabrous..........................................................................................................................................................................2

-. Leaf blades pilose at least along the abaxial side when young.........................................................................................................3

2. Leaf blades at least 2 times longer than wide; savanna and Amazonian rainforest vegetation........................... Eugenia stictopetala

-. Leaf blades 1–1.2 times longer than wide; coastal vegetation. ................................................................................... Eugenia tingui

3. Inflorescences to 3 mm; pedicels 2–7.5 mm; larger calyx lobes to 2.5 × 3 mm; fruits globose to oblate, 7–9 × 7–12 mm. .............. ............................................................................................................................................................................. Eugenia cerradensis

-. Inflorescences to 11 mm; pedicels 5–16 mm; larger calyx lobes to 4 × 4.5 mm; fruits elliptic, 12–20 × 10–12 mm ......................... ......................................................................................................................................................................... Eugenia pantanalensis

Figures

FIGURE 4. Eugenia tingui. Holotype (scale = 50 mm).