Pagamea spruceana Vicentini & Prata 2016, sp. nov.
Creators: name: Prata, Eduardo Magalhães Borges
name: Carvalho, Rangel Batista De
name: Vicentini, Alberto
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Gentianales
Rubiaceae
Pagamea
Pagamea spruceana

description: Pagamea spruceana Vicentini & Prata, sp. nov. (Figs. 1, 2)
Type:— Brazil. Amazonas: Mun. São Gabriel da Cachoeira, Rio Içana, Lago Jauacanã, 0°23’ N, 67°33’ W, 2 November 1987, C. Farney & W.A. Rodrigues 1859 (holotype INPA, isotype MO).
Pagamea spruceana differs from other functionally dioecious species of the genus by its capitate and puberulous inflorescences and narrowly elliptic leaf blades with revolute and puberulous margins, and is the only species known from long-term inundated igapós in the Amazon. Pagamea spruceana is similar to P. capitata because of the capitate inflorescence and leaves with revolute margins; the former can be distinguished from the latter by the elliptic leaf blades, acute or acuminate at apex (vs. ovate, strongly acuminate at apex in P. capitata), caducous stipules (vs. persistent), and petioles and peduncles glabrous or puberulous (vs. densely pubescent).
Treelets 2–6 m (4 ± 1.7 m) tall; stems 1–8 cm in diameter; outer bark brownish to darkish, slightly to strongly fissured longitudinally; branchlets brownish to darkish. Stipules sheathing, cylindrical with 4–8 apical setae, 5–14 mm (9.2 ± 2.4 mm) long, caducous or only the base persistent, usually puberulous. Leaves opposite, usually grouped at the terminal portion of growth units, some branchlets almost entirely composed (up to 10 cm) of leaf scars; petioles 5.9–22 mm (12.3 ± 3.7 mm) long, glabrous to densely puberulous; blades narrowly elliptic, 44–116 x 12–37 mm (69 ± 16 x 21 ± 5.7 mm), acute at base, acute or cuspidate at apex, coriaceous, glabrous to densely puberulous abaxially, glabrous adaxially, margin puberulous and usually revolute, midrib sparsely to densely puberulous abaxially and adaxially, venation eucamptodromous, veins arching, with 4–7 (5 ± 0.9) secondary veins on each side of midrib, densely puberulous abaxially and glabrous adaxially, with 0–6 domatia at axils of secondary veins. Breeding system functionally dioecious. Inflorescences capitate, peduncules 8.9–51 mm (32 ± 9.7 mm) long, greenish or reddish orange at maturity, sparsely puberulous, the main axis 0–4(9) mm (3.1 ± 3.2 mm) long, secondary axis absent or very short. Flowers small, distylous, sessile. Calyces cup-shaped, 1.5–4.1 mm long, cream-colored or greenish, glabrous inside and glabrous or sparsely puberulous outside, 4-lobed, 0.3–2.2 mm (0.9 ± 0.4 mm) long. Corolla campanulate, 5.5 mm long, cream-colored or greenish; tube glabrous inside; lobes 4, valvate, 4 mm long, puberulous abaxially, densely pubescent adaxially with hairs usually longer at the base. Functionally staminate plants: Inflorescence with 30–40 (34.6) flowers; stamen 4, exserted, inserted at the base of the corolla tube, dorsifixed near the base; anthers oblong, ovary secondarily superior, 2-locular, non functional, ovules solitary in each locule, distally puberulous; style short, <0.5 mm, stigmatic lobes 2 appressed against each other, non-papillose, not receptive. Functionally pistillate plants: Inflorescence with 15–50 (26.6) flowers; stamen 4, exserted, inserted at the base of the corolla tube, dorsifixed near the base, non functional; anthers oblong, densely packed with raphides, lacking pollen grain; ovary secondarily superior, 2- locular, ovules solitary in each locule, distally puberulous; style long,> 1 mm long, stigmatic lobes 2, open, papillose, receptive. Cupule 2.4–5.4 x 4.1–7.7 mm (4 ± 1.5 x 5.6 ± 1.1 mm), reddish orange, glabrous inside, glabrescent outside. Fruits a fleshy drupe, ellipsoid, 5.2–8.7 x 4.2–5.6 mm (7.1 ± 1.5 x 5 ± 0.7 mm), black, basal portion included in the cupule. Pyrene 2, hard, obdeltoid, single-seeded.
Distribution and habitat:— This species is known from the Içana and Uaupés Rivers Basins in the Upper Rio Negro region (Figure 3), State of Amazonas, Brazil. It occurs in open vegetation or low forests in long-term inundated white-sand habitats on the margin of lakes and rivers (igapó s).
Flowering and fruiting: —Flowering plants were found in June and fruiting specimens (some with few old flowers) were collected in November and December.
Conservation status: —The geographical distribution of Pagamea spruceana corresponds to one of the less threatened regions in the Brazilian Amazon, which is mostly protected by the Brazilian laws (Protected Areas and Indigenous Territories according to Instituto Socioambiental 2016). Pagamea spruceana can therefore be assessed as Least Concern (LC) according to IUCN categories and criteria (IUCN 2015), despite its narrow distribution.
Etymology: —The specific epithet is dedicated to Richard Spruce (1817–1983). Although Spruce has never collected this species, he made many collections and described several species of Pagamea.
Additional collection examined (paratypes): — BRAZIL. Amazonas. São Gabriel da Cachoeira, Igarapé Jurupary, Rio Uaupés, 1°37’0” N, 68°53’0” W, 94 m, 2 November 1932, A. Ducke 24417 (F); Igarapé Tibuiari, afluente do Rio Uaupés, Monte Cristo, 0°5’0” N, 67°20’0” W, 74 m, 22 November 1987, M.I. Kawasaki 242 (NY); Rio Içana, acima de Peraiauara, 1°0’0” N, 68°0’10” W, 99 m, 14 May 1973, M.F. Silva & P. Machado 1530 (INPA, US); Rio Içana, Vila de Jauacanã, 0°33’47” N, 67°24’9” W, 73 m, 27 June 2004, A. Vicentini & L. Rodríguez 2266 (MO); loc. cit., 27 June 2004, A. Vicentini & L. Rodríguez 2276 (MO); Rio Uaupés, Comunidade Monte Cristo, 67°14’34” N, 0°01’41” W, 72 m, 18 June 2009, F.A. Carvalho, A. Vicentini, M.H. Terra-Araújo, N.C. Dávila & J.M. Brito 1608 (INPA); loc. cit., 18 June 2009, F.A. Carvalho, A. Vicentini, M.H. Terra-Araújo, N.C. Dávila & J.M. Brito 1612 (INPA); loc. cit., 18 June 2009, F.A. Carvalho, A. Vicentini, M.H. Terra-Araújo, N.C. Dávila & J.M. Brito 1614 (INPA); Rio Piraiauara, afluente do Rio Içana, 0°49’09” N, 67°32’52” W, 79 m, 5 December 2013, E.M.B. Prata, N.C. Dávila, J.E. Nascimento-Junior, F. Cabral & O.F. Menezes 1948 (INPA); Rio Piraiauara, afluente do Içana, 0°49’10” N, 67°32’45” W, 85 m, 5 December 2013, E.M.B. Prata, N.C. Dávila, J.E. Nascimento-Junior, F. Cabral & O.F. Menezes 1955 (INPA); Rio Içana, Vila de Jauacanã, 0°33’56” N, 67°23’52” W, 73 m, 6 December 2013, E.M.B. Prata, N.C. Dávila, J.E. Nascimento-Junior, F. Cabral & O.F. Menezes 1959 (INPA); Rio Içana, Vila de Jauacanã, 0°33’58” N, 67°23’48” W, 73 m, 6 December 2013, E.M.B. Prata, N.C. Dávila, J.E. Nascimento-Junior, F. Cabral & O.F. Menezes. 1960 (INPA); Rio Içana, Vila de Jauacanã, 0°33’58” N, 67°23’48” W, 73 m, 6 December 2013, E.M.B. Prata, N.C. Dávila, J.E. Nascimento-Junior, F. Cabral & O.F. Menezes 1961 (INPA).
description: Published as part of Prata, Eduardo Magalhães Borges, Carvalho, Rangel Batista De & Vicentini, Alberto, 2016, Pagamea spruceana (Rubiaceae, Gaertnereae), a new species from flooded white-sand forests in the Upper Rio Negro region, Brazil, pp. 186-192 in Phytotaxa 269 (3) on pages 187-190, DOI: 10.11646/phytotaxa.269.3.2, http://zenodo.org/record/13651353