Calyptranthes arachnicola Sobral & M.C.Souza, 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 : 58-60

1. Calyptranthes arachnicola Sobral & M.C.Souza , sp. nov.

Type:— BRAZIL. Rio de Janeiro: mun. Mangaratiba, Reserva Ecológica do Rio das Pedras, Alto da Cabiúna, Toca da Aranha , 11 January 1999, J.M.A.Braga, M.G. Bovini & C.M. Mynssen 5130 (holotype RB! ; isotype HUFSJ! ). Figure 1 .

This species is apparently related to Calyptranthes ursina , from which it is kept apart by its larger blades (to 150 × 46 versus to 100 × 30 in C. ursina ), inflorescences pendulous (vs. erect), slender (axis to 0.7 mm wide vs. 1.5–2 mm wide) and ebracteate (vs. with bracts to 20 × 5 mm), with flowers laxly distributed along the inflorescence (vs. crowded at the apex of the branches) and evidently apiculate buds (vs. not visibly apiculate). It also reminds Calyptranthes fusiformis , but it is distinguished from it by the pilose inflorescences and flowers (versus glabrous in C. fusiformis ) and buds shortly apiculate (apiculum to 1.7 mm vs. to 7 mm).

Tree to 3 m. Cortex exfoliating (according to the specimen Lira Neto 534). Twigs terete or subterete, sometimes dichotomously branching, when young with simple brown ascending trichomes 1.5–2 mm, these soon deciduous, the older ones light brown or grey; internodes 35–50 × 0.8–1,5 mm. Leaves with petioles 5–9.5 × 0.8–1.5 mm, with trichomes as the twigs and turning glabrous with age, slightly sulcate adaxially; blades narrowly elliptic to oblong, 120–150 × 31–46 mm, 3.2–4.2 times longer than wide, mostly concolorous or sometimes discolorous when young, dull light brown when dry, occasionally the surface undulate mostly along the lateral and secondary lateral veins, the adaxial face glabrous, the abaxial face densely covered by brown trichomes to 1.5 mm when young, these becoming very scattered and mostly restricted to the midvein with age; glandular dots to 10/mm², smaller than 0.1 mm in diameter, visible on both sides, sometimes slightly excavated adaxially and moderately raised abaxially; apex markedly acuminate in 12–21 mm; base cuneate; midvein finely impressed adaxially and raised abaxially; lateral veins 25 to 35 at each side, leaving the midvein at angles about 60º, finely raised on both sides; marginal vein 1–2.3 mm from the finely undulate and sometimes moderately revolute margin. Inflorescences pendulous, two arising opposite from the same point of a branch, arising from brachyblasts below the leaves or at the base of new twigs, sometimes with triangular-lanceolate bracts to 8 × 2 mm at their bases, racemiform or paniculiform, pilose, the main axis 35–75 × 0.2–0.7 mm, with simple ascending brown trichomes 0.7–1 mm, with 3 to 15 flowers frequently in groups of three, the branches to 7–8 × 0.1–0.2 mm, when paniculiform the peduncles to 65 mm; bracts linear, at the base of the ramifications, 3.5–4 × 0.1–0.2, sometimes bracteoles at the base of some flowers (what also could be interpreted as bracts at the base of groups of flowers) 1–2 × 0.1 mm, deciduous at anthesis; flowers uniformly pilose with brown trichomes to 1 mm; buds elliptic, 4–4.5 × 1.5–1.6 mm; calyx lobes fused into a markedly apiculate calyptra to 2 × 1.5 mm, the apiculum 1–1.7 mm; petals in flowers examined one, very irregular, to 1.5 × 1 mm; stamens about 60, in bud to 3 mm, the anthers globose, to 0.2 × 0.2 mm, eglandular; calyx tube glabrous, to 1.5 mm deep; style to 4 mm in bud, the stigma punctiform; ovary with two locules and two ovules per locule. Fruits globose or slightly oblate, immature, 6 × 6–7 mm, crowned by the calyx tube; seed one, with brown shining testa; embryo very immature, not examined.

Distribution, habitat, phenology:—This species was collected in coastal rainforests at altitudes 200–400 m elev. in the municipality of Mangaratiba, in the southern portion of Rio de Janeiro; flowers were collected in December and January and fruits in July.

Conservation:—The municipality of Mangaratiba has an area of 356 km ² ( IBGE 2016b), with about 3,800 collections registered there ( INCT 2016, JBRJ 2016), and an average of 10 collections/km², that can be considered a good sampling effort. Considering this, the existence of only three collections from a relatively small area (1,300 ha; see Luz et al. 2011) may be an indicative of its rareness. Nevertheless, although the scarcity of collections and the small extent of occurrence may indicate a potentially vulnerable species, we do not have additional information regarding the quality of the environment at the collection place; so, it seems presently adequate to score this species as DD (Data Deficient) according to IUCN conservation criteria ( IUCN 2001).

Affinities:—This species is apparently related to Calyptranthes ursina G.M. Barroso & Peixoto (1996: 79 ; no type image available online) and C. fusiformis M.L. Kawasaki (1996: 508 ; type image: SP barcode 001310), from which it is kept apart by the characters given in the diagnosis.

Etymology:—The epithet is derived from the Latin translation for the collection place, Toca da Aranha (i. e., spider’s home in Portuguese).

Paratypes:— BRAZIL. Rio de Janeiro: mun. Mangaratiba, Reserva Ecológica do Rio das Pedras; trilha para o Cambucá , 21 December 1996, J.A. Lira Neto & M.G. Bovini 534 ( RB!, HUFSJ!, UB) ; idem, 05 July 1997, J.A. Lira Neto, R.H.P. Andreata, O. Marquete, C. Meisner, I. Cristina & Valéria 554 ( RB!, F, K, UB) .

Figures

FIGURE 1. Calyptranthes arachnicola—holotype. Insert: detail of inflorescence from isotype at HUFSJ (scale: 10 mm).