Rudgea infundibuliformis Bruniera & I.G. Costa, 2022

Bruniera, Carla P., Costa, Idimá G. & Zappi, Daniela C., 2022, Rudgea infundibuliformis (Palicoureeae, Rubiaceae), a new species from Southeastern Brazil, Phytotaxa 548 (1), pp. 106-112 : 107-109

Rudgea infundibuliformis Bruniera & I.G. Costa , sp nov. ( Figs. 1 & 2 ).

Type: — BRAZIL. Rio de Janeiro: Mun. Italva, Quimbira , Mata do Quimbira , 21°27’22.04’’S, 41°35’47.12’’W, ca. 70 m, 8 October 2016 (fl), I.G. Costa 849 (holotype HUFABC !; isotypes HUFSP!, MO!, RB!, SPF! – to be distributed) .

Diagnosis: — Rudgea infundibuliformis sp. nov. resembles R. minutifolia Bruniera & Torres-Leite (in Torres-Leite et al. 2018) by the relatively small leaves and stipules, terminal compound cymes with short peduncle, and distinctly lobed calyx; the former differs from the latter in having leaf blades with hairy-pocket domatia in the axils of secondary veins beneath (vs. absent in R. minutifolia ), and broadly infundibular corolla with the outer surface densely tomentose (vs. narrowly infundibular, and glabrous).

Shrubs ca. 2 m tall; branches terete, striate, brownish and strigose when young, later gray and glabrous, internodes 2 – 17 mm long. Stipules with basal sheath ca. 0.5 mm long, interpetiolar portion orbicular to triangular, 1.5 – 3 × 2 – 3 mm, present at 2(– 3) upper nodes, with ca. 0.5 mm long, appendages inserted at the apex of a dorsal appendage with ca. 1 – 1.5 mm long, caducous. Leaves with petioles 2 – 6 × 1 mm, canaliculate above, striate to glabrous; blades elliptic to obovate, (2 –)3.3 – 7(– 8.5) × (1 –)1.5 – 3(– 3.7) cm, acute to truncate at base, acute to acuminate at apex, margin entire, chartaceous, discolorous, drying green, paler beneath, glabrous in both faces; midrib prominent, scabrous or glabrous beneath, canaliculate and glabrous above, secondary veins 6–7 on each side of midrib, hairy pocket domatia at the axils of secondary veins below, tertiary venation visible by the naked eye above. Inflorescence erect, terminal compound dichasium, up to 5 × 5 cm, corymbiform in outline, 9–15-flowered; peduncle 3–5 mm long, secondary branches 5–15 mm long, green, glabrous; bracts narrowly lanceolate, ca. 1 mm long, with appendages at margin, pedicels 1–4.5 mm long, glabrous, green. Flowers 5-merous, heterostyly unknown. Hypanthium 1–1.5 mm long. Calyx lobed, green; tube ca. 0.3 mm long; lobes widely ovate, 1.5–2 × 1.5 mm, cuspidate at apex, glabrous, margin densely ciliate. Corolla broadly infundibular, 11–13 mm long, white, externally densely tomentose, glabrous at the base, throat densely tomentose; tube 5–7 × 1–2 mm; lobes lanceolate, 5–6 × 1.5–2 mm, patent to slightly reflexed at anthesis, apex not corniculate. Filaments (probably long-styled morph) ca. 1 mm long; anthers ca. 1.5 mm long. Nectar disc ca. 0.5 mm tall, centrally depressed. Style (probably long-styled morph) 12–13 mm long, puberulous, bifid, decurrent, each lobe ca. 2 mm long, verrucose. Fruits not seen.

Etymology: —The specific epithet infundibuliformis refers to the shape of the corolla, one of the distinctive features of this species.

Distribution and Habitat: —The new species was collected in the locality of Quimbira, municipality of Italva, bordering with the town of Cardoso Moreira, in state of Rio de Janeiro, southeastern Brazil. The area is suburban, surrounded by several rural activities, such as livestock pasture and small farms. The locality is within the Atlantic Rainforest biome.

Phenology: — Collected with flowers in October and November.

Conservation Status: — Critically Endangered (CR). B2ab (ii,iii,iv,v), D. The area of occupancy (AOO) was calculated to be of 4 km 2. The AOO is less than 10 km 2, being known from a single locality, and by less than 50 mature individuals, placing this species in the category of Critically Endangered. It occurs in the dwindling Atlantic Rainforest, a biome much impacted in Rio de Janeiro over the last two centuries. Besides, the collection locality is not included in any type of conservation unit, leading to great concern regarding the future of this new species.

Paratype: — BRAZIL. Rio de Janeiro: Mun. Italva, Quimbira , 21°27’23”S, 41°35’47”W, 70 m elev., 16 November 2014 (fl), I.G. Costa 597 ( RB) .

Figures

FIGURE 1. Some diagnostic features of Rudgea infundibuliformis. A. Abaxial face of leaves, with the domatia in the axils on detail. B. Node of the branch, showing the interpetiolar portion of the stipule with a dorsal appendage and the base of two leaves. C. Calyx and hypanthium of the flowers. D. Dissected flower, with the calyx and gynoecium removed, showing the corolla broadly infundibular and densely tomentose outside, and the androecium represented by four anthers (one removed). Scales:A. 1 cm, B. 3 mm, C. 2 mm, D. 5 mm. Drawn by D.C. Zappi.

FIGURE 2. Photos of Rudgea infundibuliformis. A. Flowering branch. B. Detail of inflorescence with flower buds and open flower in lateral view. C. Open flowers, with the right one in frontal view. Photos by Idimá G. Costa.