Myrcia petrophila Sobral, 2015

Sobral, Marcos, Faria Jr, Jair E. Q., Ibrahim, Marla U., Lucas, Eve J., Rigueira, Dary, Stadnik, Aline & Dcnat-Ufsj, Daniel Villaroel, 2015, Thirteen new Myrtaceae from Bahia, Brazil, Phytotaxa 224 (3), pp. 201-231 : 218-220

9. Myrcia petrophila Sobral , sp. nov. Type: Brazil. Bahia, mun. Wenceslau Guimarães, Reserva Estadual de Wenceslau Guimarães, Trilha da Torre , 13º34’49” S, 39º42’17” W, 20 January 2012, R. F. Monteiro, J. Aguirre-Santoro, M. Reginato & L. Daneu 553 (holotype RB!; isotype NY). Figure 10 .

This species is apparently related to Myrcia reticulosa , from which it is distinguished through its leaves with relatively longer petioles (ratio blade length / petiole length about 10:1 versus about 20: 1 in M. reticulosa ), blades with mostly rounded basis (vs. mostly cordate), pauciflorous inflorescences (with up to five flowers vs. twenty or more) and pilose flowers (vs. glabrous).

Shrub to 2.5 m. Twigs grey, somewhat applanate, with dense erect simple brown trichomes to 0.2 mm when young, glabrous with age; internodes 20–35 × 2–4 mm. Leaves with petioles 4–5 × 0.7–1.2 mm, adaxially canaliculate, with trichomes as the twigs when young; blades elliptic to widely elliptic, 32–63 × 24–39 mm, 1.3–1.7 times longer than wide, pilose when young, adaxially with simple light brown trichomes to 0.5 mm restricted to the midvein, abaxially uniformly covered with simple brown trichomes to 0.3 mm, glabrous when adult, discolorous when dry, the young ones shining adaxially, dull abaxially; glandular dots 5 to 10/mm², about 0.1 mm in diameter, about exactly one gland per areole, visible on the adaxial side of young blades, scarcely visible in adult ones, although the adult blades sometimes presents abaxially scars of fallen trichomes that may be confounded with minute glands; apex obtuse to rounded; base rounded or slightly cordate above the petiole; midvein finely sulcate adaxially, strongly raised abaxially; lateral veins 9 to 12 at each side, leaving the midvein at angles of 70–80°, visible and sometimes raised on both sides, the secondary lateral veins and higher level venation strongly reticulate in young blades; marginal vein 1–1.6 mm from the markedly revolute margin. Inflorescences axillary or at the apex of branches and not subtended by leaves, racemiform, two per branch, with three to five flowers, the axis 40–57 × 2–3 mm, applanate, with simple brown trichomes to 0.4 mm, the apical flower sessile and in the three-flowered inflorescences dichasium-like, the lateral flowers with pedicels 5–10 × 1–1.2 mm; bracts widely ovate, to 3 × 2 mm, with scattered simple trichomes to 0.2 mm, more dense abaxially; bracteoles narrowly ovate, to 3–4 × 2 mm, slightly carenate, pilose as the bracts, persisting after anthesis; flower buds globose or slightly oblate, to 6 × 5–7 mm, the ovary externally densely covered with simple brown trichomes to 0.2 mm, clearly distinct from the calyx lobes, these glabrous or scarcely pilose, markedly glandular abaxially; calyx lobes five, imbricate before anthesis, rounded or oblate, unequal between them, 3–4 × 2.5–5 mm, patent at anthesis, more or less densely covered with trichomes to 0.3 mm adaxially; petals apparently five, white, elliptic, 6.5–8 × 5–6 mm; stamens not counted, to 6 mm, pink proximally and white distally (according to type label), the anthers elliptic, to 0.6 × 0.3 mm, eglandular; staminal ring to 4.5 mm in diameter, with trichomes as the calyx lobes; calyx tube about 0.5 mm deep, glabrous; style 9–11 mm, the stigma punctiform; ovary trilocular, with two ovules per locule. Fruits not seen.

Distribution, habitat and phenology:—This species in presently known only from the type material, collected in rock outcrops in the coastal rainforest domain of the northeastern Brazilian state of Bahia; flowers were collected in January.

Conservation:—The municipality of Wenceslau Guimarães has been relatively well surveyed botanically (see details under Eugenia caloneura ), with an average of 4.3 collections/km², the fact of this species being known for only one collection may be an indicative of its rareness. Nevertheless, in the lack of additional environmental information, this species must be presently scored as DD (Data Deficient) according to IUCN conservation criteria ( IUCN 2001).

Affinities:—The blades with one gland per areole and the trilocular ovary are characters that allow assigning Myrcia petrophila to the informal “group 6” of the phylogenetic scheme of Myrcia proposed by Lucas et al. (2011); it is apparently related to Myrcia reticulosa Miquel (1850: 794 ; type image: K barcode 000018555), to which it is compared in the diagnosis.

Etymology:—The epithet is derived from the Greek words for “rock-loving”, alluding to the rock-dwelling habitat of the species.