Rinorea cardenasii Hoyos-Gómez, 2025

Hoyos-Gómez, Saúl E., Ballard Jr., Harvey E., Callejas Posada, Ricardo & Wahlert, Gregory A., 2025, Taxonomic clarifications, a new combination, and three new species of Neotropical Rinorea (Violaceae), PhytoKeys 256, pp. 151-174 : 151-174

1. Rinorea cardenasii Hoyos-Gómez sp. nov.

Type.

Colombia • Dept. Guaviare: Mpio. San José del Guaviare, Serranía de la Lindosa, vereda Cerro Azul, camino desde la casa de José Noe por la trocha hacia el Raudal , 02°31'35"N, 72°52'16"W, 200–220 m, 20 Sep 2023, S. E. Hoyos-Gómez et al. 5393 (holotype: HUA [acc. no. 236209; barcode HUA 0049795 ]!; isotype: HUA [acc. no. 236210; barcode HUA 0049796 ]!) .

Diagnosis.

Rinorea cardenasii is similar to Rinorea macrocarpa (Mart. ex Eichler) Kuntze by the opposite leaves and racemose inflorescence, but it differs by the obovate lamina (vs. elliptic lamina in R. macrocarpa ), 4 to 6 major secondary vein pairs (vs. 7 to 9), domatia present (vs. absent), connective scales with entire margin (vs. praemorse margin), filaments free (vs. filaments connate at the base forming a staminal tube), fruit 2.5–3.2 × 2–2.5 cm (vs. 3.5–5.8 × 2.5–3 cm), two pubescent seeds per valve (vs. three glabrous seeds), and seeds 5–7 mm in diam. (vs. 7.6–9 mm in diam.).

Description.

Treelets 3–4 m tall, terminal branchlets pubescent with dimorphic ferruginous pubescence, small erect trichomes 0.2–0.3 mm long and longer appressed trichomes 0.4–0.6 mm long. Leaves opposite, petiolate; petiole 3–7 cm, pubescent with dimorphic ferruginous pubescence, small erect trichomes 0.1–0.3 mm long and longer appressed trichomes 0.4–0.6 mm long; stipules deciduous, free, triangular, 3–6 × 1.3–1.8 mm, densely pubescent with appressed ferruginous trichomes 0.2–0.3 mm long; lamina obovate, 6–15 × 4–8 cm, foliaceous, veins abaxially pubescent with appressed ferruginous trichomes 0.3–0.5 mm long, veins pinnate, semicraspedodromous, with 4 to 6 pairs of major secondary vein, secondary veins with unequal spacing between them, percurrent, base symmetrical, cuneate, margin crenate and ciliolate with ferruginous trichomes 0.2–0.3 mm long, apex mucronate to acuminate, acumen 0.8–1.5 (2) cm long, leaf domatia present. Inflorescence terminal, racemose, solitary, 3–5 × 0.5–1 cm, central axis brown, densely pubescent with erect ferruginous trichomes 0.2–0.3 mm long; pedicels 0.7–1.5 mm, pubescent with erect ferruginous trichomes 0.2–0.3 mm long, articulated at the base; bracts persistent, triangular, 1.5–2 × 1.2–1.5 mm, costa pubescent with appressed golden ferruginous trichomes 0.2–0.3 mm long, margin ciliolate, apex apiculate; bracteoles persistent, triangular, 1–1.2 × 0.7–0.9 mm, opposite, costate, pubescent with appressed trichomes 0.2–0.3 mm long, margin ciliolate with ferruginous trichomes, apex mucronulate. Flowers 3–4 × 3–4 mm, subzygomorphic; sepals triangular, 1.8–2 × 1.5–2 mm, with 5 to 9 longitudinal veins, pubescent with appressed golden trichomes 0.2–0.3 mm long, margin ciliolate, apex apiculate; petals white, lanceolate, 2.5–3 × 1–1.3 mm, costa pubescent with appressed ferruginous trichomes 0.3–0.5 mm long, margin ciliolate, apex acute; stamens 2.2–2.5 × 0.4–0.6 mm, filaments free, dorsal gland covering the basal part of the filament, sparsely pubescent with golden appressed trichomes 0.1–0.2 mm long, anthers ellipsoid, 0.5–0.7 × 0.4–0.5 mm, glabrous, connective 0.9–1 mm long, apically pubescent with 1 to 2 golden setae 0.3–0.5 mm long, glabrescent; dorsal anther connective scale lanceolate, 2–2.2 × 0.5–0.7 mm, margin entire, brown; ovary globose, 0.8–1 × 0.9–1 mm, pubescent with appressed golden trichomes 0.3–0.4 mm long; style filiform, erect, 1–1.2 mm long, pubescent with trichomes 0.2–0.3 mm long, stigma acute. Fruit a symmetrical subligneous capsule dehiscent along three sutures, ellipsoid, 1.5–2.5 × 1.5–2 cm, apex truncate, green when fresh, brown when dry, dimorphic golden pubescence with small erect trichomes 0.2–0.3 mm long and longer appressed trichomes 0.4–0.6 mm long. Seeds two per valve, globose, 3–4 mm diam., brown at maturity, densely pubescent with golden trichomes 0.3–0.5 mm long (Fig. 1 ).

Distribution and habitat.

Rinorea cardenasii is an endemic species from the Departments of Caquetá and Guaviare in eastern Colombia, where it is restricted to areas of lowland forest at elevations of 200 to 350 m (Fig. 2 ). It grows in the vicinity of rocky outcrops of the Serranía de La Lindosa and the Serranía del Chiribiquete, which are the westernmost outcrops of the Guiana Shield in Colombia.

Etymology.

Rinorea cardenasii is named in honor of the late Dairon Cárdenas López (1957–2022) of the Instituto Amazónico de Investigaciones Científicas ( SINCHI) and director of the COAH herbarium in Bogotá, Colombia. Cárdenas López made many significant contributions to the knowledge of the flora of Amazonian Colombia.

Phenology.

The species has been recorded with flowers and fruit in September.

Conservation status.

Rinorea cardenasii has an extremely limited distribution and is known from only three collections representing three occurrences and two subpopulations. It has a geographic range in the form of an estimated EOO of 8 km 2 (adjusted upward from 3.017 km 2 following IUCN guidelines, 2024) and an AOO of 8 km 2. The three occurrences are located outside protected areas and are threatened by deforestation for timber extraction, agriculture, and grazing. With respect to the most serious plausible threat of deforestation, the three occurrences represent two locations, which falls within the limits for “ Endangered ” status. We infer an ongoing loss of habitat that will lead to continuing decline in AOO, EOO, habitat extent and quality, and the number of subpopulations and mature individuals. Rinorea cardenasii is therefore preliminarily assessed as “ Endangered ” [EN B 1 ab (i, ii, iii, iv, v) + 2 ab (i, ii, iii, iv, v)] in accordance with the IUCN Red List Categories and Criteria ( IUCN 2024).

Notes.

Rinorea cardenasii is most similar morphologically to R. macrocarpa and R. pabongonzaleziorum . Rinorea cardenasii can be differentiated from R. pabongonzaleziorum by its symmetric, cuneate lamina base (vs. symmetric, decurrent lamina base in R. pabongonzaleziorum ), its petals with a pubescent costa and ciliolate margin (vs. costa with scattered pubescence and entire margin), its pubescent sepals with 5–9 longitudinal veins (vs. densely pubescent sepals without longitudinal veins), its free filaments (vs. connate filaments forming a staminal tube), and its two pubescent seeds per valve (vs. one glabrous seed per valve). Table 1 highlights the key morphological differences among Rinorea cardenasii , R. macrocarpa , and R. pabongonzaleziorum .

Additional specimens examined.

Colombia. Dept. Caquetá: • Mpio. Solano, Cuenca media del río Cuñare, bosque de tierra firme , 0°32'4"N, 72°37'58"W, 350 m, 15 Nov 2000 (fl), H. Mendoza et al. 11676 ( JAUM, FMB) . Dept. Guaviare: • Mpio. San José del Guaviare, Serranía de la Lindosa, vereda Cerro Azul, camino por la trocha hacia el Raudal , 02°31'34"N, 72°52'15"W, 200 m, 13 Aug 2024 (fr), S. E. Hoyos-Gómez et al. 5779 ( HUA, JAUM, COAH, FMB) .

Figures

Figure 1. Rinorea cardenasii Hoyos-Gómez A habit B detail of pubescence on young twig C detail leaf domatia, abaxial surface D leaf architecture E inflorescence F flower G detail of flower showing free filaments, petals, and gynoecium H sepals, abaxial surface I petals showing detail of abaxial and adaxial surfaces J stamens showing detail of abaxial and adaxial surfaces K gynoecium M fruit N detail of fruit showing two seeds per carpel O seed (A – O: H. Mendoza et al. 11676 [JAUM]).

Figure 2. Distribution of Rinorea cardenasii (stars) and R. pabongonzalezii (triangles).