Calyptranthes biconvexa M.C.Souza & Sobral, 2016

Sobral, Marcos, Mazine, Fiorella F., Leoni, Lúcio, Souza, Marcelo C. & Melo, Eugênio A. D., 2016, Five new southeastern Brazilian Myrtaceae, Phytotaxa 253 (1), pp. 57-70 : 60

2. Calyptranthes biconvexa M.C.Souza & Sobral , sp. nov.

Type:— BRAZIL. Rio de Janeiro: mun. Guapimirim, Granja Monte Olivete, trilha das Andorinhas , 500 m, 18 January 1995, J.M.A. Braga, M.G. Bovini & J.R. de Figueiredo 1738 (holotype RB!) . Figure 2 .

This species is apparently related to Calyptranthes lanceolata , from which it is distinguished by the leaves with smaller petioles (to 4 mm versus to 15 mm in C. lanceolata ) and blades (to 180 mm vs. to 300 mm), blades with midvein markedly biconvex adaxially (vs. sulcate) and the smaller inflorescences with winged axis (to 20 mm vs. to 200 mm, the axis not winged).

Shrub to 2.5 m. Plants glabrous, except for brown dibrachiate trichomes to 0.1 mm in the flower buds. Twigs applanate and sometimes with small longitudinal wings to 0.4 mm wide, sometimes with four to six imbricate narrowly triangular cataphylls to 7 × 0.5 mm at their bases; internodes 10–20 × 1–2 mm. Leaves with petioles 3.5–4 × 1–1.5 mm, adaxially sulcate; blades narrowly elliptic to oblong, 110–180 × 28–50 mm, 3.6–4 times longer than wide, discolorous when dry, dark dull brown adaxially, lighter abaxially; glandular dots scarcely visible through light, about 0.1 mm in diameter and about 20/mm², sometimes slightly excavated adaxially; apex acuminate in 15–22 mm; base obtuse; midvein raised and biconvex—i.e., elevated with a visible central longitudinal furrow—adaxially, raised and lighter than the surface abaxially; lateral veins 20 to 30 at each side, leaving the midvein at angles 70–80º, moderately raised on both sides, lighter than the surface abaxially, with secondary lateral veins of smaller gauge occasionally visible; marginal vein 0.8–2 mm, occasionally a second vein to 1 mm from the plane or moderately revolute margin. Inflorescences axillary or ramiflorous, in parts of the branches devoid of leaves, racemiform, applanate and sometimes with wings to 0.2 mm wide, axis 12–20 × 0.8–1.5 mm, with three to five sessile flowers; bracts linear, to 1.5 × 0.2 mm; flower buds fusiform to globose, to 3–4.5 × 1.5–3 mm, apiculate, the apiculum 0.4–0.8 mm; calyx lobes fused and opening through a calyptra to 1.5 × 2 mm; petals not seen in the flowers examined, possibly abortive; stamens (in bud) to 3 mm, the anthers globose, to 0.3 mm, eglandular; staminal ring to 2 mm in diameter, glabrous; style to 4 mm, the stigma punctiform; calyx tube to 1 mm deep, glabrous; ovary with two locules and two ovules per locule. Fruits not seen.

Distribution, habitat, phenology:—This species is presently known only for the type collection, from dense rainforests in the municipality of Guapimirim, in the central portion of Rio de Janeiro, at about 500 m elev.; flowers were collected in January.

Conservation:—The municipality of Guapimirim has an area of 360 km ² ( IBGE 2016b), from which are registered about 4,100 plant specimens ( INCT 2016, JBRJ 2016), with an average of more than 11 collections/km², a good sampling effort. The existence of only one collection of Calyptranthes biconvexa may be an indicative of its rareness; nevertheless, we do not have additional information regarding the environmental conditions of the collection site, and then we score this species as DD (Data Deficient) according to IUCN conservation criteria ( IUCN 2001).

Affinities:— Calyptranthes biconvexa is apparently related to C. lanceolata O. Berg (1857 –1859: 51; type image: BR barcode 0000005230907!), from which it is distinguished by the characters given in the diagnosis.

Etymology:—The epithet is allusive to the adaxially biconvex midvein of this species.

Figures

FIGURE 2. Calyptranthes biconvexa—isotype at HUFSJ (scale: 50 mm). Insert: detail of inflorescence (scale: 10 mm).