Dendrosipanea prancei Delprete, 2018

Delprete, Piero G., 2018, Two new species of the tribe Sipaneeae (Rubiaceae) from white-sand areas of Brazilian and Colombian Amazon, Phytotaxa 382 (1), pp. 125-135 : 127-129

Dendrosipanea prancei Delprete , sp. nov.

Type :— BRAZIL. Amazonas : Basin of Rio Negro, Rio Uneiuxi [0°38’01”S, 65°11’02”W, ca. 30 m alt.], 5 km above mouth, periodically flooded savanna on sand, treelet 1 m tall, corolla white, 8 November 1971 (fl), G. T. Prance, P. J. M. Maas, D. B. Woolcott, O. P. Monteiro & J. F. Ramos 16199 (holotype, INPA [Acc. No. 34418]; isotypes, F [Acc. No. 1841650], MO [Acc. No. 2728504], NY, S [Acc. No. 10-28034], US [Acc. No. 2868603]). ( Fig. 1 ) .

Dendrosipanea prancei Delprete is similar to D. spigelioides in having leaf blades acute at apex, with primary and secondary veins not impressed (i.e., complanar) above and slightly prominent below; the former differs from the latter by the corollas 19 − 24.5 mm long, tubes 11–14 mm long, 1.6–1.9 mm wide at base, 2 − 2.8 mm wide at mouth, and lobes ovate to narrowly ovate, 7.5–10.5 × 4.5–5 mm, acute at apex; whereas D. spigelioides has corollas 27 − 30 mm long, tubes 16–20 mm long, 2–2.5 mm wide at base, 3.5 − 4.5 mm wide at mouth, lobes oblong to ovate-oblong, 12–16 × 5–7.5 mm, obtuse to acute at apex.

Shrub or treelet, 1–1.3 m tall; leafy branchlets terete to slightly tetragonal, glabrous, red, distal nodes lightly resinous. Stipules free or adnate to petioles, ovate-triangular to broadly triangular, 1.5–3 × 1.8 − 4.5 mm, bifid at upper third to half the length, lobes narrowly triangular to acuminate and reduced to two teeth in older stipules, glabrous outside, margin glabrous or sometimes hispidulous-ciliolate, sericeous and with band of colleters at basal portion inside. Leaves subsessile to short-petiolate; petioles 2 − 5 mm long, glabrous; blades elliptic, oblong-elliptic to narrowly oblong-elliptic, 4–10 × 1.3–3 cm, acute to decurrent at base, acute at apex, subcoriaceous, dark green, shiny above and pale green below when fresh, drying brown above and pale brown below; glabrous throughout, margins scarcely or not revolute, primary and secondary veins not impressed above and slightly prominent below; secondary veins 6–11 each side of midrib. Inflorescence cymose, frondose, long-branched, 6–16 cm long (including peduncle and flowers), 3–8 cm broad, terminal branches scorpiod, expanding at fruit maturity; rachis glabrous; peduncle 2.5–5.5 cm long; secondary branches subtended by a pair of leaf-like bracts (i.e., pherophylls); these ovate, elliptic to oblong-elliptic, (2.5–)3.5–7 × 0.9–2.2 cm; each flower with one bracteole inserted on the opposite side of the branch; bracteoles sessile, oblonglanceolate, 1–1.5 × 0.5–0.8 mm, acuminate at apex, often with 1-2 tiny teeth on each side, glabrous, sparsely ciliolate. Flowers with pedicels 3 − 8 mm long, glabrous. Hypanthium turbinate to narrowly obovoid, 1.5–1.7 × 1.2 − 1.5 mm, glabrous. Calyx tube absent (lobes free) or extremely reduced; lobes subequal to unequal, oblong to narrowly oblong, 1.5–5 × 0.4–0.7 mm, acute at tip, glabrous or sparsely strigillose outside, sericeous at base inside, margins glabrous, with 1–2 colleters at each sinus. Corolla hypocrateriform, white (sometimes tube green), 19 − 24.5 mm long; tube narrowly infundibuliform, 11–14 mm long, 1.6–1.9 mm wide at base, 2 − 2.8 mm wide at mouth, glabrous or with a few appressed-strigulose hairs outside, villous and densely yellow-pubescent at mouth inside; lobes left-contorted, ovate, narrowly ovate to elliptic, 7.5–10.5 × 4.5–5 mm, sometimes slightly asymmetrical and of slightly different width within the same corolla, acute at apex, glabrous outside, densely papillose inside, margins glabrous. Shortstyled flowers unknown. Long-styled flowers (e.g., Prance et al. 15472): stamens included, inserted at 2.7 mm from the base of corolla; filaments 3.7 mm long; anthers linear-oblong, 3.5 − 3.7 × 0.2 − 0.3 mm, acute at both ends; style barely exserted (only branch tips beyond corolla mouth), 14–15 mm long, glabrous, style branches oblong, 2 mm long. Infructescence, capsules and seeds unknown.

Distribution and ecology:—Only known by two collections from the Rio Uneiuxi Basin, affluent of the Rio Negro, state of Amazonas, Brazil, and one collection from the Department of Guainía, Amazonian Colombia; on black-water periodically flooded, white-sand savannas, at 30–110 m altitude.

Phenology:—Flowering specimens were collected in October and November.

Suggested conservation status:— Dendrosipanea prancei is only known from two sites (collected in 1971) along the Rio Uneiuxi Basin, affluent of the Rio Negro, state of Amazonas, Brazil, and one distant site (collected in 2005) in the Guainía Department, Amazonian Colombia. The extent of occurrence (EOO) is therefore not calculable. This species is known from remote white-sand savannas, which are subject to frequent fires during the dry season, often started by local communities populations; therefore, it is considered Threatened [T] according to IUCN criteria ( IUCN 2012, 2016).

Etymology:—The specific epithet of this taxon is dedicated to Sir Ghillean Prance, eminent botanist that collected for several decades in the Amazon basin of Brazil. After working for 25 years at the New York Botanical Garden, he assumed the position of Director of the Royal Botanic Gardens, Kew ( Langmead, 1995). He is currently retired, and continues to be very active, especially with taxonomic revisions of Neotropical families and conservation initiatives. He was the first to collect this species, on white-sand campinas of the Rio Uneiuxi, in collaboration with a team of botanists and field technicians. It is a great honor to dedicate this specific epithet to him.

Notes:—The new species here described is only known by three collections, all of them with the style barely exserted beyond the corolla mouth, and the stamens included, inserted at 2.7 mm from the base of the corolla tube. As the other two species recognized in the genus are distylous, it is here assumed that this species is also distylous, and that these three gatherings are long-styled forms.

Additional specimens examined (paratypes): COLOMBIA. Guainía: Mun. Inirida, km 50 de la carretera Huesito (Río Inirida – Puerto Caribe – Río Guainia), Sector de Caño Pato, bosque abierto con sotobosque denso sobre llanura alluvial, 3°08’14”N, 67°47’34”W, 110 m, 3 October 2005 (fl-imm fr), D. Cardenas & A.L. Bermudez 16831 (NY).

BRAZIL. Amazonas: Basin of Rio Negro, Rio Uneiuxi [ca. 0°32’S, 65°03’W, ca. 30 m alt.], 100 − 200 km above mouth, black-water flooded savanna forest on sand, shrub 1.3 m tall, corolla tube green, lobes white with yellow hairs at center, 21 October 1971 (fl), G.T. Prance, P.J.M. Maas, D.B. Woolcott, O.P. Monteiro & J.F. Ramos 15472 (INPA, MG, NY, US).

Figures

FIGURE 1. Dendrosipanea prancei. A. Branch with terminal, frondose inflorescence. B–C. Stipule shapes present on the same branch. D. Detail of inflorescence branch, with secondary branches subtended by two leaf-like bracts (i.e., pherophylls). E. Flower in anthesis. F. Dissected long-styled flower, with stamens inserted at basal portion of corolla tube. A–D: drawn from Prance et al. 16199 (F, S); E–F: drawn from Prance et al. 15472 (US). Illustration by Piero Delprete.