Eugenia choungiensis Byng & N. Snow, 2016

Byng, James W., Barthelat, Fabien, Snow, Neil & Bernardini, Benedetta, 2016, Revision of Eugenia and Syzygium (Myrtaceae) from the Comoros archipelago, Phytotaxa 252 (3), pp. 163-184 : 169-170

1. Eugenia brasiliensis Lamarck (1789: 203)

Shrub or small tree about 4– 6 m. Petiole 5–13 mm. Leaves slightly coriaceous, glabrous, glossy. Blades 6.5–13 × 2.5–5 cm, obovate-elliptic or obovate-oblong, base cuneate, apex acute or acuminate; secondary vein pairs 12–20. Inflorescences axillary, flowers solitary. Pedicels 1.5–3.5 cm. Calyx lobes 4–6 × 3–4 mm, oblong or obovate. Petals ca. 11–14 × 7 mm, obovate, white. Stamens 4–5 mm long. Style ca. 6 mm long. Fruits 1–2 cm in diameter, sub-globular, typically maturing dark purplish-black.

Habitat and ecology: — Humid and dry forests.

Specimens examined:— MAYOTTE [ FRANCE]. Grande Terre, Combani, Mont Combani, 25 November 2005 (fr.), F. Barthelat 1525 (P!, MAYOTTE!) ; Bouéni, Boungoudranavi Sommet, 18 October 2005 (fl.), F. Barthelat 1512 (P!, MAYOTTE!) .

Notes:— This Brazilian species is cultivated widely in tropical regions for its edible fruits. It is recorded from Mayotte and likely to be cultivated or naturalised on other islands.

2. Eugenia choungiensis Byng & N. Snow , sp. nov. Type : — MAYOTTE [ FRANCE]. Mlima Choungi, 12 April 1996 (with flowers and fruits), O. Pascal 470 (holotype P! [barcode P00144741]; isotypes K!, MAYOTTE!). Figure 4

The species is similar to Eugenia viguieriana H. Perrier (1952: 167) but differs in the unequal calyx lobes, shorter, bifid styles and shorter pedicels. The species has sessile leaves that are basally cordate or rounded and broadly acute at the apex.

Shrubs to 2 m tall; bark smooth, grey; glabrous. Branchlets 1–2 mm diameter, grey, distally winged, peeling, grey to reddish brown. Leaves sessile to subsessile, coriaceous, drying pale dull olive-green beneath, dark green to brownish-green above. Blades 1.5–6.6 × 1.1–3.8 cm, ovate; base round to cordate; apex broadly acute; midvein drying dark to light brown; secondary veins prominent, 8–14, visible above but prominent beneath; intramarginal vein prominent, 1–2 mm from the margin. Inflorescences terminal or axillary, cymose, 1–8-flowered. Bracteoles triangular, ca. 1.5 mm long. Pedicels 3–6 mm, longitudinally furrowed. Flowers 6–8 mm in diameter at anthesis, buds ca. 3 mm in diameter. Calyx lobes ca. 2–3 × 2.2 mm, rounded, inner two larger than outer two, gland-dotted. Petals ca. 3 × 2.5 mm, orbicular, white, gland-dotted. Stamens many, not counted; filaments 2–3 mm, white; anthers ca. 0.8 mm long, oblong, sub-basifixed. Style in female flowers 1.5–2.8 mm, stigma bifid, ca. 1.2 mm wide at apex. Style and stigma in male flowers not seen. Fruits 0.7–1 × 0.7–1 cm, globular, red to green, longitudinal lines present, crowned by persistent calyx.

Distribution:— Endemic to Mont Choungi on Mayotte [ France].

Habitat and ecology:— Montane forests from 400‒ 700 m.

Affinities: — The Malagasy species Eugenia viguieriana is vegetatively similar in sharing a cordate leaf base, blade shape and size, but the type specimen (Viguier 1181, P!) notably has a long (ca. 4 mm) and simple style and much longer pedicels (10‒13 mm long), in contrast to the bifid style and shorter pedicels of E. choungiensis . Geographically the few specimens correctly determined as E. viguieriana also are distributed on the east coast of Madagascar.

Etymology:— Eugenia choungiensis is named after its type locality, Mlima Choungi, Mayotte.

Paratypes:— MAYOTTE [ FRANCE]. Mlima Choungi , 2 May 1999 (fl.), M. Pignal 1429 (P!) ; 2 May 1999 (fr.), M. Pignal 1431 (P!).

Conservation status:— The species is only known from about a dozen mature individuals at the type locality with an Area of Occurrence (AOO) of 0.5 km 2. Given that the species habitat is highly restricted at Mlima Choungi and is under threat from various anthropogenic activities, it is assigned a preliminary status of Critically Endangered (CR C2a(i,ii); D) according to the IUCN Red List Criteria ( IUCN 2014).

Note:— The species was previously determined as Syzygium cordatum based primarily on the sessile cordate leaf base. After thorough morphological examination the species was found to belong to Eugenia due to its prominent petals, short pedicels and bifid stigma. The only flowers seen have bifid stigmas, which suggests the species is also morphologically androdioecious.

Figures

FIGURE 4. Eugenia choungiensis Byng & N. Snow. A leaves and flower; B close-up of flower and bud. (Photos by F. Barthelat). Scale bar = 5 mm.