Pleiochiton blepharodes (DC.) Reginato, R.Goldenb. & Baumgratz

Description

Description Author and Date: Marcelo Reginato, José Fernando Andrade Baumgratz, and Renato Goldenberg, based on A Taxonomic revision of Pleiochiton (Melastomataceae, Miconieae). Reginato, M., Baumgratz, J.F.A., & Goldenberg, R. Brittonia, 65(1), 2013, pp. 16–41

Type: Brazil. São Paulo: “In sylvis Brasiliae propé Bananal et alibi, Provinciae Sebastianopolitana et S. Pauli”, C.F.P. Martius s.n. (holotype: M).

Description: Young branches, leaves, inflorescences, and hypanthium sparsely to densely covered by eglandular trichomes, 1–3 mm long, more densely so on young branches, petioles and leaf abaxial surface along acrodromous nerves, sometimes mixed with glandular trichomes on inflorescences and hypanthia; older branches glabrous, leaf adaxial surface sometimes glabrous. Old branches 1–5(–9) mm diam., nodes 2–8(–14) mm diam. Leaves isophyllous; petioles (2.5–)4–10 mm long; blade 3–6(–8.5) x (1–)1.5–4.5 cm, ovate, elliptic or lanceolate, membranaceous or chartaceous, apex acuminate or shortly acuminate, base obtuse or rounded, margin slightly crenulate and flat or slightly revolute, ciliate (trichomes 1.5–2 mm long); acrodromous nerves 3 or 3+2, basal or up to 3 mm suprabasal. Cymes 2–5(–8) cm long, lateral, rarely terminal, congested, sometimes lax, 3–10(–15)-flowered, 2(–3) pairs of paraclades plus an apical triad or rarely only a triad, sometimes the paraclades alternate, anthopodia inconspicuous, rarely up to ca. 12 mm long; bracts 3–11 mm long, usually lanceolate, sometimes ovate, oblong, elliptic or obovate, ciliate, sparsely covered with eglandular trichomes, rarely glabrous; bracteoles 3–9.5 mm long, involucral, but sometimes not involucral. Flowers 5-merous, pedicels 0.3–1.2 mm long. Hypanthium 2.7–4.5 x 2.1–4 mm, tubular, torus glabrous. Calyx tube 0.5–1.2 mm long, lobes 0.5–1(–1.6) mm long, deltoid, rarely triangular; external teeth (2.8–)4–5.6 mm long. Petals 4–8 x 2.5–4.5 mm, ovate or oblong to obovate, apex rounded or shortly acuminate. Stamens slightly unequal in size, the shorter filaments 2.2–4.5 mm long, the longer ones 3–5.5 mm long, anthers yellow, straight, linear, the shorter ones 2–3.5 mm long, the longer ones 3–4.3 mm long, pore ventral; connective not prolonged below the thecae, unappendaged, sometimes with a dorso-basal tooth. Ovary (1/8–)1/4–1/3 inferior, 1.6–3.3 x 1–2.5 mm, conical, apex with glandular trichomes (0.8–1.5 mm long); style 6.5–11 mm long. Berries 5–7.5 x 4–5.5 mm; seeds 0.6–0.9 x 0.4–0.5 mm, 150–280 per fruit.

Habitat and Distribution: The distribution of Pleiochiton blepharodes is the broadest among the species of Pleiochiton, and overlaps the distribution of the entire genus. It has been collected from Taquaritinga do Norte (Pernambuco) to Palhoça (Santa Catarina; Fig. 3C). This is the only species that reaches the northernmost part of Atlantic Forest, in inland montane areas in Pernambuco known as “brejos de altitude”. It is also the only one collected in lowland forests and islands close to the continent, like Ilha Grande (Rio de Janeiro), Ilha do Cardoso (São Paulo), and Ilha do Mel (Paraná). In Bahia it has been collected from 600 to 900 m above sea level, and from sea level up to 900 m in Rio de Janeiro and São Paulo, 800 m in Paraná, and 500 m in Santa Catarina.

Phenology: Pleiochiton blepharodes has been collected with flowers and fruits during almost the whole year, but most flowering samples were collected in December and January, and fruiting samples from February to April.

Taxonomy and Systematics: This species is recognized by the membranaceous to chartaceous leaves, the lateral inflorescences (only one specimen showed an additional terminal inflorescence) with flowers in congested triads, the conspicuous bracteoles and stamens with linear, straight anthers with ventral pores. Pleiochiton blepharodes is the species with the broader morphological variation in the genus, mostly in the indumentum density, size and texture of the leaves, and inflorescence characters, such as bract morphology, number of flowers and the degree to which flowers are congested in the triads. Pleiochiton parasiticum seems to be the most closely related species to P. blepharodes, sharing a similar indumentum, and the shape of the bracteoles, hypanthium, anthers and ovary. Nevertheless, it differs from P. blepharodes by the anisophyllous leaves (the larger ones usually two to three times larger than the smaller), the calyx with the internal lobes completely adhering to the external teeth, and the glandular trichomes on the torus. Some specimens of P. blepharodes, including Glaziou 16031 cited by Cogniaux (1886-1888) and recent collections from Paraty, Angra dos Reis and Tinguá (Rio de Janeiro), have been identified as P. glaziovianum. Those are individuals of P. blepharodes with a set of unusual characters, like the inflorescences with sparse glandular trichomes and alternate paraclades, and the flowers on lax triads. The morphological similarity of the epiphytic Clidemia and species of Pleiochiton had been mentioned before (Wurdack, 1962; Goldenberg et al., 2005). The transfer of C. blepharodes and C. parasitica to Pleiochiton agrees with a recent phylogenetic hypothesis for this group (Reginato et al., 2010a). Detailed information on the taxonomic transfers is presented in Reginato et al. (2010b).

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