Myrcia delicata Gressler & Sobral, 2016

Sobral, Marcos, Caliari, Cláudia P., Gressler, Eliana, Mazine, Fiorella F., Magenta, Mara & Viana, Pedro L., 2016, Seven new southeastern Brazilian species of Myrcia (Myrtaceae), Phytotaxa 247 (1), pp. 27-44 : 28-30

1. Myrcia delicata Gressler & Sobral , sp. nov.

Type:— BRAZIL. São Paulo: mun. Ubatuba, Parque Estadual da Serra do Mar, núcleo Picinguaba , margins of Rio da Fazenda and Trilha do Corisco, 70 m high, S 23°20’11.8” S, 44°49’55.3” W, 22 February 2009, E. Gressler 754 (holotype RB! ; isotype HRCB! ). Figures 1 , 2 .

This species is related to Myrcia neocambesseadeana , from which it is distinguished by the twigs covered with appressed trichomes (versus glabrous in M. neocambessedeana ), constantly triflorous inflorescences with one flower at the apex of the main axis and two at the apex of secondary axes (vs. with five apically congested flowers), the main axis 35–50 mm long and the secondary axes evident, 8–9 mm long (vs. 40–50 mm long, the secondary axes inconspicuous, 2–3 mm long), the main axis less than five times longer than the secondary ones (vs. main axis more than ten times longer than the secondary ones). It can also remind Myrcia curtipendula , differing through its pilose (vs. glabrescent in M. curtipendula ) and shorter blades (to 60 × 14 mm vs. up to 100 × 30 mm).

Tree 2–9 m high, erect or occasionally prostrate with adventitious roots along the stem, these becoming thick and helping support the plant. Twigs densely covered with appressed coppery simple trichomes 0.7–1 mm long, the internodes 9–16 mm long × 0.6–0.8 mm wide; apical gems densely pilose, covered with white trichomes to 0.5 mm. Leaves with petioles 1.5–2 × 0.5–0.8 mm, pilose as the twigs and bearing in the axile 2 to 4 pairs of linear, glabrous colleters 0.2–0.4 × 0.1 mm; blades lanceolate, ovate-lanceolate or oblong-lanceolate, 38–60 × 8–14 mm, 3.6–4.7 times longer than wide, visibly discolorous when dry, dark green adaxially and dull, pale green abaxially, the adaxial side glabrous or with sparse grey trichomes to 0.1 mm on the midvein, the abaxial side with three types of grey trichomes, the surface with somewhat appressed and scattered trichomes to 0.2 mm, these interspersed with somewhat erect larger trichomes to 0.5 mm, and the midvein densely covered with appressed trichomes to 1 mm; glandular dots <0.1 mm in diameter, 5 to 10/mm 2, barely visible on both sides; apex acuminate to 14 mm; base obtuse to rounded; midvein plane or slightly impressed adaxially, raised abaxially; lateral nerves 40 to 50 at each side, slightly visible and faintly salient on both sides, leaving the midvein at angles about 80°; marginal vein 0.2–0.3 mm from the margin. Inflorescences axillary, triflorous, with more or less dense erect trichomes to 0.5 mm, the axiles of the ramifications with concave, linear to lanceolate bracts 3–4 × 0.5 mm, with trichomes to 0.3 mm at the abaxial side; main axis 35–50 × 0.2–0.3 mm; secondary axes 8–9 × 0.2 mm. Flowers slightly scented, sessile at the apex of the axes; bracteoles narrowly lanceolate, 2–3 × 1 mm, slight concave or plain, with trichomes like the bracts and with 2 to 4 pairs of linear colleters like those on the petioles; flower buds globose to obovate, 3–4 × 3 mm, covered with grey to whitish trichomes 0.2–0.3 mm, these more dense above the ovary; calyx lobes five, widely triangular to hemispheric, slightly unequal, 0.8–1.5 × 1.2–1.6 mm, strongly reflexed at anthesis, with trichomes to 0.1 mm adaxially; petals five, white, orbicular, to 3 mm in diameter, adaxially glabrous and abaxially with trichomes to 0.2 mm; stamens 80 to 100, filaments 2–4 mm, the anthers globose, 0.2–0.3 × 0.3 mm, eglandular, the thecae with the interior staminal sac opening extrorsely and apically and the exterior one introrsely and basally; staminal ring to 2 mm in diameter, with dense trichomes to 0.2 mm; calyx-tube to 0.3 mm deep; styles 4–4.5 mm, proximally with scattered trichomes to 0.2 mm, otherwise glabrous, the stigma minutely capitate and verruculose; ovary bilocular, with two central-basal ovules per locule. Fruits globose to oblong, 6 to 9 mm in diameter, dark red to black when ripe; seed subglobose to widely reniform, with dark brown, easily detachable testa and embryo with two distinct, folded cotyledons surrounded by an hypocotyl.

Distribution, habitat and phenology:—This species occurs in shady locations in the interior of coastal rainforests of the municipalities of Paraty (state of Rio de Janeiro) and Ubatuba (state of São Paulo), at altitudes from 70–500 m elev.; flowers were collected from November to February, and fruits from February to September, the fruits ripening since July.

Conservation:—Most collections of Myrcia delicata are from the State Park of Picinguaba, in the municipality of Ubatuba, São Paulo, and there is only one collection known from Paraty, in Rio de Janeiro. Paraty and Ubatuba are contiguous municipalities which sum 1,648 km 2 ( IBGE 2015b), and there are about 31,500 collections from there, resulting in an average of 19 collections/km², a high sampling effort. Considering this, the fact that this species has been only sporadically collected may be an indicative of its rareness. Nevertheless, in the absence of additional environmental information, we presently score it as DD (Data Deficient) according to IUCN conservation criteria ( IUCN 2001).

Affinities:— Myrcia delicata is apparently related to Myrcia neocambessedeana E.Lucas & Sobral ( Sobral et al. 2010: 55; for description see Berg 1857 –1859: 24, under Gomidesia cambessedeana O.Berg ; type image: P barcode 02273013), a scarcely collected species from the forests of Rio de Janeiro, from which it can be distinguished by the characters given in the diagnosis.Additionally, the inflorescence structure of Myrcia delicata could occasionally remind that of Myrcia curtipendula Nic Lughadha ( Nic Lughadha et al. 2010: 21; type image: K barcode 000331907), which can bear triflorous inflorescences like those of M. delicata ; in M. curtipendula , however, the leaves are glabrescent and larger (to 100 × 30 mm). Myrcia delicata clearly matches those of informal “group 3” in the phylogenetic scheme of Lucas et al. (2011), which mainly comprises the species formerly included in the Bergian genus Gomidesia ( Berg 1855 –1856: 27).

Etymology:—From the Latin word for “delicate”, alluding to the small blades and tender inflorescences of the species.

Paratypes:— BRAZIL. São Paulo: mun. Ubatuba, Parque Estadual da Serra do Mar, núcleo Picinguaba , margens do Rio da Fazenda e Trilha do Corisco, 23°20’15.0” S, 44°49’55.5” W, 17 January 2007, E. Gressler 153 ( BHCB!, HRCB!) ; idem, 17 January 2007, E. Gressler 139 ( HRCB); 22 June 2007, E. Gressler 97 ( HRCB!) ; idem, 20 January 2008, E. Gressler 338 ( HRCB!) ; idem, 7 August 2009, E. Gressler 1115 ( HRCB!); idem, 7 August 2009, E. Gressler 1020 ( HRCB!, HUFSJ!) ; mun. Ubatuba, Sertão da praia do Puruba, fazenda Cambucá, trilha Cambucá–Cunha , SAD 69, zona 23, 17 February 2005, N.M. Ivanauskas et al. 6022 ( BHCB!, SPSF!) . Rio de Janeiro: mun. Paraty, fazenda São Roque , 4 August 1988, M.C. Marques 104 ( RB!) .

Figures

FIGURE 1. Myrcia delicata—unmounted holotype (scale: 50 mm).

FIGURE 2. Myrcia delicata—flowering twig (from Gressler 754; photo E. Gressler).