Mezilaurus sessiliflora P. L. R. Moraes & Vergne. A. Trunk 2017, sp. nov.
Creators: name: Moraes, Pedro Luís Rodrigues De
name: Vergne, Matheus Carvalho
name: Werff, Henk Van Der
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Laurales
Lauraceae
Mezilaurus
Mezilaurus sessiliflora

description: Mezilaurus sessiliflora P.L.R.Moraes & Vergne, sp. nov.   
 Type:— BRAZIL. Espírito Santo: Linhares, Reserva Natural Vale, Marco de Ferro, 19º05’52.0”S, 39º58’08.0”W, 21 January 2015, fl., immat. fr., P. L. R. de Moraes, H. van der Werff, M. C. Vergne, T. A. Pontes & M. Cruz 4577 (holotype HRCB!; isotypes CVRD!, MO!). (Figures 4–7)   
 Diagnosis: —The species can be recognized by the combination of long petioles, dilated at base, flowers sessile, receptacle glabrous inside, filaments densely pubescent, and remnants of tepals on cupules of mature fruits.   
 Description: —Trees, to 20 m tall. Twigs terete or angular, sulcate, glabrous to glabrescent or sparsely pubescent toward the tip, hairs straight, appressed, short, with inconspicuous lenticels, leaf scars conspicuous; terminal buds pubescent, hairs straight, appressed, long. Leaves alternate, clustered toward the tips of the branches, elliptic to obovate, chartaceous to coriaceous, somewhat bullate, 3.4–15.5 × 1.5–7.0 cm, base acute to cuneate, seldom obtuse, slightly asymmetric, apex acute to shortly acuminate to rounded, the margin flat to slightly revolute, sclerified, glabrous on both surfaces; the upper surface with midrib and secondary veins prominulous, the lower surface papillate, sometimes on the midrib with sparse hairs, appressed, ± short, midrib and secondary veins raised, reticulation subdense, conspicuous, prominulous, venation eucamptodromous-brochidodromous, 7–13 secondary veins on each side; domatia absent; petioles 0.9–4 cm, long, flat to slightly canaliculate, semiterete, pubescent, hairs straight, appressed, ± short, base dilated. Inflorescences subterminal, racemose, shorter than the leaves, many-flowered, glabrescent, hairs straight, appressed, short. Flowers greenish, glabrous, sessile, 3.7–4.7 × 1.9–2.2 mm; tepals 6, subequal, erect at anthesis, rigid, ovate, apex obtuse, glabrous abaxially, sparsely pubescent adaxially, inner tepals 0.9–1.0 × 0.9–1.1 mm, outer tepals 0.7–0.8 × 0.6–0.8 mm, anthers and style exserted at anthesis; stamens of whorls I, II and IV absent; stamens of whorl III 2-locular, extrorse, 1.2–1.4 mm long, the filaments free, as wide as the anthers, densely pubescent, hairs short, thick, curled, appressed, the anthers deltoid, glabrous abaxially, sparsely pubescent adaxially, apex acute-truncate, 0.5–0.7 × 0.5–0.7 mm; pistil glabrous, 1.4–1.9 mm long, style slightly shorter than the ovary, 0.6–0.8 mm long, with a longitudinal furrow, ovary ellipsoid, 0.8–1.0 × 0.5–0.8 mm, stigma discoid, small, receptacle shallow, urceolate, glabrous inside. Fruits elliptic, 2.2–2.6 × 1.3–1.5 cm, exserted; cupule saucer-shaped with remnant of tepals.   
 Additional material examined (paratypes): — BRAZIL. Espírito Santo: Linhares, Reserva Natural Vale, 19º05’51.9”S, 39º58’08.1”W, 22 February 2013, fr., G. S. Siqueira 862 (CVRD!, HRCB!, RB!), idem, 18 March 2013, fr., G. S. Siqueira 865 (CVRD!, HRCB!, MO!); idem, 19º05’50.5”S, 39º58’08.6”W, 23 September 2014, bud, immat. fr., P. L. R. de Moraes et al. 3719 (CVRD!, HRCB!); idem, 19º08’33.1”S, 40º04’45.3”W, 23 January 2015, fl., P. L. R. de Moraes et al. 4637 (CVRD!, HRCB!, MO!).   
 Sessile flowers are not a particularity of Mezilaurus sessiliflora alone, since they are also found in M. caatingae van der Werff (1987: 159) and in M. palcazuensis van der Werff (1987: 173), which differ from the former, however, in several other features. Nevertheless, sessile flowers are an unusual character in the genus (van der Werff 1987), and are not found in any other species occurring in the Brazilian Atlantic forest, viz. M. glabriantha Alves & Souza (2012: 257), M. navalium (Allemão de Cisneiros 1847: 265) Taub. ex Mez (1892: 112), and M. revolutifolia F.M.Alves & P.L.R.Moraes in Alves et al. (2011: 506). Moreover, M. glabriantha has leaves with shorter petioles, with the base not dilated, and glabrous filaments, whereas M. navalium presents narrower leaves and receptacle pubescent inside, and M. revolutifolia usually has revolute leaves and deciduous tepals on cupules of mature fruits.   
 Phenology: —Flowering specimens were collected in January and September (bud); fruiting specimens were collected from January to March and in September.   
 Etymology: —The epithet refers to its sessile flowers.   
 Conservation status: — Mezilaurus sessiliflora is so far only known from the Reserva Natural Vale. Although the species had been sampled several years ago in one of the survey plots of the reserve, fertile specimens have been collected only recently, showing that it is distinct from its congeneric species. Finding this species in the forest is a difficult task, due to its characteristic habit, i.e. the trees are tall, with fissured rhytidome that is not so common in the Lauraceae, clustered leaves at the tip of twigs, covering the inflorescences developed beneath them, with small, greenish and inconspicuous flowers. This may partially explain the small number of trees so far located, but at the same time the species seems to be rare in the reserve. However, similarly to C. baitelloanum, M. sessiliflora is here assigned as Data Deficient (DD), since we do not have more precise data about its populations.
description: Published as part of Moraes, Pedro Luís Rodrigues De, Vergne, Matheus Carvalho & Werff, Henk Van Der, 2017, Three new species of Lauraceae from the Atlantic rainforest of Brazil, pp. 149-160 in Phytotaxa 316 (2) on pages 153-156, DOI: 10.11646/phytotaxa.316.2.4, http://zenodo.org/record/13699862