Priogymnanthus saxicolus Lombardi, 2015

Lombardi, Julio Antonio, 2015, Priogymnanthus saxicolus (Oleaceae), a new species from Minas Gerais, Brazil, Phytotaxa 221 (1), pp. 66-70 : 66-70

Priogymnanthus saxicolus Lombardi , sp. nov. ( Fig. 1 , 2 , 3 )

It resembles Priogymnanthus hasslerianus (Chodat) P.S.Green through leaf shape and the inflorescence axis bracted at base, but differing by the unique character combination of persistently villose abaxial leaf surface, short congested inflorescences, and inflorescence axis and pedicels puberulent to villose.

Type:— BRAZIL. Minas Gerais, Matias Cardoso , próximo à extração de cascalho, 14º53’23.4”S 43º44’46.9”W, 530 m, 27 October 2014 (fl), Lombardi 10444 (holotype, HRCB; isotypes, BHCB, K, NY, RB) .

Tree, ca. 7 m tall, young branches hispid, old ones glabrescent; indumenta whitish; buds hispid; leaves opposite, exstipulate; petiole ca. 6–9 mm, canaliculated, hispid; blade 4.4–9.3 × 2.6–5.1 cm, elliptic, apex acute, entire, base attenuate, young leaf blade tomentose to pubescent adaxially, midrib villose, mature leaf blade glabrescent, shiny, blades villose abaxially, midrib villose to pubescent on both surfaces, chartaceous, venation pinnate with 8–13 pairs of secondary veins, midrib and veins yellowish, midrib impressed on the adaxial side, prominent on the abaxial surface, secondary veins slightly plane on adaxial side, slightly prominent on the abaxial surface, tertiary veins inconspicuous; inflorescences 7 × 7 mm, congested unbranched cymes with one terminal flower and 3–4 opposite decussate flower pairs, the first pair apparently abortive, in leaf scars or axillary; peduncle null; axis bracteate at base, puberulent to villose, bracts 1–3 × 1.2–3 mm, deltoid, pubescent, villosulous at margin; pedicels in young flowers ca. 0.5 mm, elongating up in older flowers, puberulent to villose, bracteate, the bracts of terminal flower ca. 2 × 0.7 mm, rhombic, bracts of lateral flowers ca. 3 × 2 mm, elliptic, all villosulous; calyx absent; petals 4, 2–3 × 0.6–1.3 mm, alternate with stamens, obovate to elliptic, sometimes asymmetric, apex acute, villosulous, margin ciliate, cream colored, blade glabrous, probably early caducous, stamens 4, ca. 2.5 mm long, glabrous, 2-sporangiate, 4-thecate, filament null, connective inconspicuous, anther botuliform, ca. 2.5 × 1, 5 mm, latrorse, yellow; pistil ca. 2.8 mm long, flaskshaped, glabrous, ovary ca. 1 mm long, superior, 2-locular, with 1 axillary ovule in each locule, style ca. 1.3 mm long, slightly flattened, stigma ca. 0.5 mm long, terminal, slightly 2-lobed at early anthesis; mature fruit not seen. immature subspherical, green.

Phenology:—Flowering in October and January, immature fruits in January.

Distribution and habitat:― Brazil (Minas Gerais), Priogymnanthus saxicolus is only known from few trees ( P. H. A. de Melo, pers. comm.), growing on xerophytic limestone outcrops with deciduous vegetation in the boundaries of the town of Matias Cardoso, northern Minas Gerais ( Fig. 1A ). This area is characterized by limestone formations: large areas with flat slabs interspersed with sharp-edged boulders and gentle hills of gravel and boulders. Priogymnanthus saxicolus would be considered as Data Deficient in any rating on the IUCN Red List Categories and Criteria. There is no information about its population in the collection area or the occurrence of this new taxon in close areas with natural vegetation. However, the conservation perspectives are not good because the collecting site is located close to a gravel mining area and there are no protections to shield this species from habitat degradation in the region. The description of this new taxon and new expeditions to its collection place are urgent to determine its population size, set prospects of future in situ conservation projects, and collect viable seeds, if present, to ensure ex situ conservation.

Vernacular name:—Unknown.

Taxonomic relationships:— Priogymnanthus saxicolus is characterized by the unique combination of persistently villose abaxial leaf surface ( Fig. 1B ), congested inflorescences, and inflorescence axis and pedicels puberulent to villose ( Fig. 2A ) that set it apart from its other two congeneric species: P. apertus and P. hasslerianus , that have glabrous leaves or abaxially pubescent midrib sides in the proximal half of blade, respectively, slender inflorescences (ca. 1.9 cm and 1.1–4.4 cm long, respectively), and inflorescence axis and pedicels glabrous ( P. hasslerianus ) or sparse hairy ( P. apertus ).

Etymology:—The specific epithet “saxicolus ” refers to the rocky limestone outcrops where this species grows.

Priogymnanthus specimens examined:— Priogymnanthus apertus : ECUADOR. El Oro: Zaruma, Portovelo (gold mine near Zaruma), 30Aug–1 Sept 1923, A. S. Hitchcock 21223 (holotype, NY). Priogymnanthus hasslerianus : BRAZIL. Goiás: Monte Alegre, Fazenda Nica, 31 Oct 2000, F. C. A. Oliveira et al.1164 ( CEN). Maranhão: Estreito, Fazenda Fronteira Alegre, canteiro de obras da AHE Estreito, 20 May 2005, G. Pereira-Silva et al. 9420 ( CEN), 7 Mar 2007, G. Pereira-Silva et al. 11272 ( CEN). Tocantins: km 21 da estrada Dianópolis-Taguatinga, 8 Dec 1991, D. Alvarenga et al. 831 ( IBGE). BOLÍVIA. Santa Cruz: Prov. Angel Sandoval, alrededores de San Fernando, 16 Oct 2001, J. C. Catari et al. 146 ( MO). PARAGUAI. Central: in regione lacus Ypacaray, Aug 1913, E. Hassler 11889 ( C, MO).

Figures

FIGURE 1. Priogymnanthus saxicolus. A. Habitat, limestone outcrops with deciduous vegetation. B. Vegetative branch, not preserved. Photos by P.H.A. de Melo.

FIGURE 2. Priogymnanthus saxicolus.A. Fruiting branch. B. Flowering branch with villose pubescence in the pedicels and inflorescence axis. Photos by P.H.A. de Melo.

FIGURE 3. Priogymnanthus saxicolus. A. Branch with young inflorescence. B. Close-up of young inflorescence. C. View of a lateral flower. D. Terminal flower, two stamens removed, petals stretched open. (A–D from Lombardi 10444). Photo A by J.A. Lombardi, B–D by M.N. Saka.