Rinorea aymardii Hoyos-Gómez, 2024

Hoyos-Gómez, Saúl E., Callejas Posada, Ricardo & Wahlert, Gregory A., 2024, Seven new species of Rinorea (Violaceae) from the Neotropics, PhytoKeys 242, pp. 241-271 : 241-271

2. Rinorea aymardii Hoyos-Gómez sp. nov.

Type.

Venezuela. Dept. Amazonas de Atabapo: “ Caño Iguapo ” Alto Orinoco , 15 km al SE de la Esmeralda , 3 ° 8 ' N, 65 ° 27 ' W, 100–180 m elev., 20 Feb 1990, G. Aymard et al. 8050 (holotype: MO [acc. 5983541 ; barcode MO- 1980109 ]!; isotype: MA [cat. 543845 ]!) .

Description.

Rinorea aymardii is similar to R. melanodonta S. F. Blake by the lamina with domatia and symmetrical bases, filaments free and style erect, but it differs by the smaller, herbaceous, lanceolate lamina, 4–11 × 1–2.7 cm (vs. larger, coriaceous, elliptic lamina, 6.5–17 × 1.7–5.2 cm in R. melanodonta ), 7–8 major secondary vein pairs (vs. 9–12 major secondary vein pairs), abaxial tertiary venation percurrent, pubescent (vs. abaxial tertiary veins reticulate, glabrescent), petals 2.8–3 × 1–1.2 mm, with entire margin and pubescent at the apex (vs. petals 5–5.7 × 1.5–2.2 mm, with margin ciliolate and glabrous at the apex), shorter stamens, 2.8–3 mm long (vs. longer stamens, 4–4.5 mm long), dorsal gland glabrous (vs. dorsal gland pilosulous) and smaller anther connective scales, 2–2.1 × 0.7–0.8 mm (vs. larger anther connective scales, 3.2–3.5 × ca. 1.5 mm).

Treelets to 3 m tall, young branchlets strigose with erect golden trichomes 0.1–0.2 mm long, glabrescent. Leaves opposite, petiolate; petiole 1.8–3.8 mm long, pubescent with erect golden trichomes 0.1–0.2 mm long; stipules deciduous, free, lanceolate 2–2.4 × 0.9–1 mm, herbaceous, pubescent with appressed golden trichomes 0.1–0.2 mm long, apex mucronate; lamina elliptic-lanceolate, 4–11 × 1–2.7 cm long, adaxially glabrous, abaxially pubescent on the mid-vein and veins with appressed golden trichomes 0.2–0.4 mm long, with 7–8 major secondary vein pairs, secondary veins with irregular spacing, vein angles smoothly decreasing proximally, mixed epimedial tertiary veins, symmetrical and rounded base, margin crenate, apex acuminate, acumen 0.5–1 cm, mucronate, leaf domatia absent. Inflorescence axillary, terminal or subterminal, racemose, 1.7–4 cm long, 0.8–1 cm diam., axis pubescent with erect golden trichomes 0.2 mm long; pedicels 1.7–2 mm, pubescent with erect golden trichomes 0.2 mm long, articulated near the middle; bractlets persistent below articulation, opposite, ca. 1 × 1 mm, herbaceous, the costa pubescent with appressed golden trichomes 0.2 mm long, peduncle bracts triangular, ca. 1 × 1.2 mm, herbaceous, pubescent with appressed ferruginous trichomes 0.2 mm long, margin ciliolate. Flowers 3–3.5 × 3–3.5 mm, sepals subequal in size and shape, triangular, 1.4–2.4 × 1–1.3 mm, 3–5 - veined, costa pubescent with appressed golden trichomes, 0.2 mm long, margin ciliolate, apex apiculate; petals lanceolate, 2.8–3 × 1–1.2 mm, pubescent with erect golden trichomes 0.1–0.2 mm long near the apex, margin entire, apex acute, cream-coloured in vivo, brown when dry; stamens 2.8–3 mm long, filaments free, glabrous, 0.4–0.6 mm long, dorsal glands glabrous, completely covering the filaments; anthers lanceolate, 1–1.2 × 0.4–0.5 mm, glabrous, apex rounded, connective 1–1.2 mm long, dorsal connective scale lanceolate, 2–2.1 × 0.7–0.8 mm, scarious, brown – orange, margin subentire; ovary globose, 0.8–1 × 0.8–0.9 mm, pubescent with erect golden trichomes 0.2–0.3 mm long; style erect, filiform, glabrous, 1.7–1.9 × ca. 0.1 mm, stigma acute. Fruit unknown. (Fig. 3 )

Distribution and habitat.

Rinorea aymardii , which is only known from the type specimen, occurs the Alto Orinoco – Casiquiare Biosphere Reserve in Amazonas State, Venezuela, a biogeographic area classified as the Province of Imerí in the Boreal Brazilian Dominion (sensu Morrone (2014)). It grows in terra firma humid forest at elevations of 100– 180 m. The landscape of the type locality is characterised by gently sloping (10–20 %) hills composed of granitic and quarzitic rocks ( Aymard 2000). (Fig. 4 )

Etymology.

Rinorea aymardii honors the Venezuelan botanist Gerardo Aymard, who has made significant contributions to the taxonomic knowledge of the flora of Venezuela, especially the south-western part of the country in the Río Negro and Orinoco River Basins.

Phenology.

The species is only known from one flowering specimen collected in February.

Conservation status.

Rinorea aymardii has a geographic range in the form of an EOO of 4 km 2 and AOO of 4 km 2. It is currently known only from the type collection, which represents one location within the terra firma forests of the Alto Orinoco – Casiquiare Biosphere Reserve in Venezuela where it is threatened by illegal logging and mining. Based on its limited AOO, the single location and the projected continuing decline in the quality of habitat due to uncontrolled deforestation and resource extraction, the species might be preliminarily assigned to the “ Critically Endangered. ” However, given the difficulty accessing this inadequately explored area, it is likely there are additional occurrences that would allow a more accurate assessment of the risk of extinction than is possible at this time. The species is therefore preliminarily assigned to the IUCN (2012) Category of “ Data Deficient ” [ DD].

Notes.

Rinorea aymardii is sympatric with R. macrocarpa from which it can be differentiated by the smaller lamina 4–11 × 1–2.7 cm with crenate margins (vs. larger lamina 5.5–21.5 × 2–9.2 cm with subentire to subcrenate margins in R. macrocarpa ), filaments free (vs. filament fused into a tube) and style filiform (vs. style conical).

Figures

Figure 3. Rinorea aymardii Hoyos-Gómez A habit B leaf architecture C detail of leaf, abaxial surface D infructescence E flower F sepals, abaxial surface G petals, abaxial surface H stamens, showing both surfaces I gynoecium. (A – I: G. Aymard 8050 [MO]).

Figure 4. Distribution of R. melanodonta (triangles), R. macrocarpa (asterisks), R. betancurii (pentagons), Rinorea aymardii (squares).