Meliosma dazae Rob. Fern. 2022, sp. nov.
Creators: name: Fernandez-Hilario, Robin
name: Reynel, Carlos
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Proteales
Sabiaceae
Meliosma
Meliosma dazae

description: 2. Meliosma dazae Rob.Fern., sp. nov. (Figures 2–4)
Diagnosis:— Meliosma dazae most closely resembles M. caballeroensis Cornejo (2008b: 93) but differs by the shape of leaf blades (elliptic vs. oblanceolate), outer petals length (0.66–0.95 mm long vs. ca. 2 mm long), and shape of inner petals (entire vs. bifid). Additionally, it differs from other congeneric by the combination of glabrous leaves, leaf blades (14-)17–33 × 4.2–7.3 cm, sepals 4, 0.92–1.18 mm long, glabrous outer petals 0.66–0.95 mm long, glabrous and broadly lanceolate inner petals 0.40–0.43 mm long, inner petals longer than the filaments, and drupes 1.2–1.4 × 1.1–1.3 cm.
Type:— PERU. Junín: Prov. Chanchamayo, Dist. San Ramón, road to Mina Pichita, just above mine, 11°05′40″ S, 75°25′03″ W, 2100 m, 18 Nov. 2002 (fl.), R. T. Pennington, A. K. Monro & A. Daza 1290 (holotype MOL! [barcode 000112]; isotype E! [barcode E00200744], MOL! [barcodes 000113, 000114, 000115, 000116]).
Tree up to 15 m tall and 21 cm DBH. Terminal branchlets terete, 6–7 mm diam., glabrous and lenticellate. Leaves alternate; petioles terete, 1.3-2.8 cm long, slightly basally swollen (pulvinus-like), glabrous, black when dry; leaf blades coriaceous, (14-)17–33 × 4.2–7.3 cm, elliptic, apex acute, base cuneate, margin entire, slightly discolorous; venation brochidodromous, with 16–23 secondary veins, 4–22 mm distant from each other, central secondary veins with (66-)72–86°, intersecondary veins absent, rarely weak; adaxial surface with the midvein and secondary veins impressed, the reticulation barely visible; abaxial surface with the midvein salient, secondary veins prominent and the reticulation visible; adaxial surface flat, glabrous, brown when dry; abaxial surface glabrous, light brown when dry. Inflorescence a terminal or axillar erect panicle, 15–23 × 6–8 cm, multiflorous, branched 2-times, peduncle and axes moderately to densely pubescent; bracts scale-like, glabrous, 2.5–4.5 mm long; bracteoles scale-like, margin minutely ciliate, ca. 1 mm long, bracteoles near to the flowers with margins sparsely ciliate. Flowers green to whitish green in fresh, sessile. Sepals 4, subequal, 0.92–1.18 × 0.66–0.94 mm, ovate to deltoid, margin minutely ciliate. Petals 5, glabrous; outer petals 3, 0.66–0.95 × 0.55–0.82 mm, widely ovate, margin entire; inner petals 2, 0.40–0.43 mm long, longer than the filaments, broadly lanceolate, basally adnate to the stamens, apex obtuse. Stamens 2, 0.48–0.58 mm long; filaments 0.28–0.33 mm long; connective with a slightly triangular tip; anthers 0.22–0.27 × 0.49–0.51 mm, thecae separated by connective tissue; staminodes 3, 0.44–0.61 mm long, capitate, with two lateral projections at the base, opposite to outer petals and basally adnate to them, one of the three staminodes with one vestigial theca. Ovary 0.34–0.46 mm long, ovoid, glabrous, with an annular disk; style minute; stigma punctiform. Infructescence erect, ca. 20 × 10.8 cm, peduncle and axes glabrescent. Drupes 1.2–1.4 × 1.1–1.3 cm, subspherical, with the base compressed, black when dry. Seeds not seen.
Habitat and distribution:— Meliosma dazae is a endemic Peruvian tree known from a single locality in the montane forests of the District of San Ramón (Junín), on moderate to markedly steep slopes. At this locality, M. dazae occurs in mature forests between 2100–2400 m.
Phenology:— Flowering in November, and fruiting in September and November.
Etymology:— This species is named after Aniceto Daza Y., technician and long-time research collaborator at the herbarium of the Facultad de Ciencias Forestales of the Universidad Nacional Agraria La Molina. During the last 40 years, the Daza’s collections have been an important contribution to the knowledge of the tree flora of the Junín region and to Peruvian dendrology (see Ríos 1982; Reynel et al. 2020).
Conservation status:— Meliosma dazae is known from three collections from the San Ramón district of the Chanchamayo Province (Department of Junín), and in this region the mature rainforests are under continuous anthropic pressure (see additional comments under M. chanchamayensis). Following IUCN (2012, 2019) guidelines and based on estimated area of occupancy of 8 km 2, we recommended the category Critically Endangered CR B2ab(iii) for this species.
Discussion:— Vegetatively M. dazae most closely resembles M. caballeroensis Cornejo (Bolivia and Peru), M. glossophylla Cuatrecasas (1948 [1949]: 216) (Colombia to Bolivia) and M. littlei (Ecuador) due to its long (up to 35 cm) and narrow (<8 cm) leaf blades with entire margins. Whitin this group, M. dazae differs from M. caballeroensis by its elliptic leaf blades (vs. oblanceolate), outer petals 0.66–0.95 mm long (vs. ca. 2 mm) and entire inner petals (vs. bifid). Moreover, M. dazae differs from M. littlei by its petioles 1.3-2.8 cm long (vs. 3–4 cm), leaf blades with 16–23 secondary veins (vs. 10–12) and drupes 1.2–1.4 × 1.1–1.3 cm (vs. ca. 1.8 × 1.6–1.7 cm). Finally, M. dazae differs from M. glossophylla by its brown adaxial leaf blades when dry (vs. greyish), absent intersecondary veins (vs. present) and moderately to densely pubescent inflorescences (vs. glabrous).
Probably M. dazae is most closely related to M. frondosa Cuatrecasas & Idrobo (1955: 193) (Panama to Bolivia) and M. minutipetala Arbeláez (2004: 13) (Bolivia and Peru) by sharing sepals that are evidently longer than petals. However, M. dazae can be easily differentiated from former by its leaf blades with cuneate bases (vs. rounded to subcordate in M. frondosa), flowers with 4 sepals 0.92–1.18 mm long (vs. 5 sepals 2.2–2.5 mm long), and inner petals slightly longer than the filaments (vs. inner petals of similar length as the stamens). Also, M. dazae differs from the latter by its elliptic leaf blades (14-)17–33 × 4.2–7.3 cm, (vs. obovate, 23.5–31 × 9.3–12 cm in M. minutipetala), flowers with 4 sepals (vs. 5) and entire inner petals (vs. bifid).
Paratypes:— PERU. Junín: Prov. Chanchamayo, Dist. San Ramón, Concesión para la Conservación Puyu Sacha, Parcela PR a 1.4 km al oeste del centro de interpretación, 11°05′51″ S, 75°26′14″ W, 2400 m, 19 Sep. 2017 (fr.), R. Fernandez-Hilario et al. 1176 (HOXA!), Fundo APRODES, 11°05′53″ S, 75°26′16″ W, 2395 m, 21 Sep 2017 (st.), A. Claros 564 (MOL!).
description: Published as part of Fernandez-Hilario, Robin & Reynel, Carlos, 2022, Two new species of Meliosma (Sabiaceae) from the premontane and montane forests of the Selva Central of Peru, pp. 45-54 in Phytotaxa 559 (1) on pages 49-52, DOI: 10.11646/phytotaxa.559.1.5, http://zenodo.org/record/7009358