Rinorea gemmulata J.F.C. Oliveira & L.P. Queiroz, 2020

Oliveira, José Florencio Cerqueira & Queiroz, Luciano Paganucci De, 2020, Rinorea gemmulata (Violaceae): A New Species from Eastern Brazil, Phytotaxa 435 (1), pp. 50-56 : 51-54

Rinorea gemmulata J.F.C. Oliveira & L.P. Queiroz , sp. nov. ( Fig. 1 , 2 )

Among the neotropical species of Rinorea sect. Publiflora with thyrsoid inflorescences and opposite leaves with symmetrical bases, R. gemmulata is very similar to R. vaupesana L.B. Sm. & A. Fernández (1954: 98) and R. villosiflora Hekking (1983: 254) , from which it differs by presenting (i) conspicuous perulate buds with imbricate cuspidate scales at the apices of the branches (versus absent in both similar species), (ii) stamens completely free (versus stamens fused into a tube), (iii) connectives velutinous to villous outside, glabrous inside, and connective scales glabrous on both sides (versus connectives and connective scales glabrous in R. vaupesana ; connectives and connective scales villous on both sides in R. villosiflora ), (iv) inflorescences axillary, paired, rarely solitary (versus solitary in both) and (v) capsule symmetric (versus asymmetric in both). From the sympatric R. ramiziana Glaziou ex Hekking (1983: 255) it differs by the opposite leaves (versus leaves alternate and congested in R. ramiziana ), stamens free (versus joined into a tube) with velutinous to villous connective (versus connective glabrous), and fruits densely velutinous along its entire length (versus fruit sparsely pilose towards the apex).

Type: — BRAZIL. Bahia: Itaetê, distrito de Colônia, mata ciliar do Rio Una, sentido cachoeira do Roncador, 13°04’29’’S, 41°08’03’’W, 332 m a.s.l., 28 November 2016, J.F.C Oliveira et al. 115 (holotype HUEFS!, isotypes ALCB!, CEPEC!, ESA!, HUEFS!, INPA!, NY!, K!, P!, RB!, SP!).

Shrubs to treelets 1–4 m tall; branchlets puberulous when young, later glabrescent; perulate buds 3–7 mm long, apical or lateral at the branch apex, scales 2–6 mm long, usually persistent at the base of the inflorescence, ovate, apex cuspidate, pilosulous to glabrescent. Stipules usually caducous, deltoid, 0.3–1 × 0.2 mm, hispidulous to puberulous. Leaves opposite, rarely whorled next to inflorescence; petiole 4–8 mm long, pubescent; lamina 5.0–15.0 × 2.5–7.0 cm, elliptical, apex acuminate, base cuneate, symmetrical, margins serrulate, glabrous on both faces except usually puberulous on the midrib and lamina base on the abaxial face, lateral veins 8–13 pairs, brochidodromous, tertiary venation scalariform. Inflorescence in axillary, lateral, terminal, or subterminal thyrsoids, paired, rarely solitary, 4–8 cm long, main axis puberulous, scars near the base of the peduncle and inflorescence branches; lateral cymules 3–5- flowered, peduncle 4–7 mm long, pedicels 1–4 mm long; bracts 0.6–2.0 mm long, pilosulous, deltoid to ovate, margin entire, ciliate; bractlets 0.5–1.0 mm long, pilosulous, ovate, margins entire, ciliate. Flowers 4–6 mm long, bisexual; sepals 1.5–2.0 × 0.5–1.0 mm, subequal, ovate, pilosulous outside, glabrous inside, margins ciliate, apex obtuse to cuspidate, 3–6-veined; petals 3–6 × 1–2 mm, greenish to yellowish white, deltoid to ovate, pilose outside and near the base inside, apex acuminate; stamens 5, 3–4 mm long, completely free, anthers c. 2 x 1 mm, glabrous, deltoidal, apex obtuse with two cusps 0.1–0.2 mm long, connective on both sides deltoid, velutinous to villous outside, glabrous inside, connective scales orange-brown, lateral-apical, ovate, glabrous on both sides, margins entire, not ciliate; ovary 1–2 mm long, ovoid to subconical, velutinous, style 1.5–2.5 mm long, glabrous, entire or rarely divided, erect to curved at the base, stigma slightly invaginate. Capsule 8–10 × c. 6 mm, elliptical, symmetric, outside densely velutinous, inside velutinous; valves 3, (sub)equals, dehiscent along three straight sutures, subtended by subpersistent floral parts. Seed one per valve, c. 4 × 3 mm, globose, glabrous.

Distribution and Habitat: — Rinorea gemmulata is known only from the states of Bahia and Espírito Santo, in the understory of seasonally dry riparian and semideciduous forests in the Paraguaçu River basin in the municipalities of Itaetê, Wagner, and Cruz das Almas in Bahia state, and in the municipalities of Conceição da Barra, Jauaré, and Linhares in Espírito Santos state ( Fig. 3 ).

Conservation Status: — Rinorea gemmulata was assessed as Endangered (EN) following the criterion B2.b.ii as it presents an Area of Occupancy of 24 km 2. It occurs in widely disjunct areas in Bahia and Espírito Santo states in small populations at very fragmented forest remnants. Although it was not recorded at any reserve, it was collected close to the Vale Natural Reserve (Linhares, Espírito Santo state).

Etymology: —The epithet “gemmulata ” refers to the perulate buds with imbricate scales at the apex of most branches. These buds rapidly give rise to new vegetative shoots or inflorescence sprouts during the first rains after the dry season.

Additional Specimens Examined (paratypes):— BRAZIL: Bahia: Cruz das Almas, mata atrás do Instituto do Fumo, 11 Sep 1983 [fl.], M.L.S. Guedes 837 (ALCB!). Itaetê, localidade de Colônia, sentido Cachoeira Roncador, rio Una, 13°05’S, 41°10’W, 25 Oct 2013 [fl., fr.], D.S. Carneiro-Torres et al. 1121 (HUEFS!). Wagner, Chapada

Diamantina, Ponto 7, margem do rio Bonito, 12°28’S, 41°16’W, 600 m alt., 12 Mar 2006 [fr.], M.L.S. Guedes 24377 (ALCB!). Espírito Santo: Conceição da Barra, Floresta Nacional do Rio Preto, trilha da Lagoa Seca 18°21’07”S, 39°50’05”W, 29 Aug 2012 [fl.], T.B. Flores & G.O. Romão 1291 (ESA!, CVRD!, MBML!, VIES!, UEC!). Jaguaré, Córrego Cachimbau, 18°58’S, 40°01’W, 05 Nov 2013 [fl.], D.A. Folii 7131 (CVRD!, RB!). Linhares, mata a 2, 6 km do início da estrada não pavimentada a rio Bananal, início desta a 10 km NW da cidade de Linhares, ponte sobre afluente do rio Doce, remanescente de floresta pluvial tropical perturbada, 07 Dec 1994 [fl.], J.R. Pirani 3444 (SPF!).

Taxonomic notes: — Rinorea gemmulata shares with R. villosiflora and R. vaupesana the opposite leaves, thyrsoid inflorescences, and capsules hairy outside ( Table 1). However, it can be differentiated from both species by having perulate buds, paired axillary inflorescences (rarely solitary), and stamens completely free. Rinorea gemmulata differs from R. villosiflora by having leaf apices acuminate (versus cuspidate) and connective scales glabrous with margins glabrous (versus villous with margins ciliate). Rinorea gemmulata and R. vaupesana also share ovaries and capsules hairy, although R. gemmulata differs by having connectives velutinous to villous outside, glabrous inside (versus glabrous on both sides in R. vaupesana ) and capsule symmetric (versus asymmetric). Additionally, their geographic distributions do not overlap: R. gemmulata occurs in Bahia and Espírito Santo states, whereas R. villosiflora and R. vaupesana are restricted to the Amazonian region.

The genus Rinorea is represented by five species in Eastern Brazilian Atlantic Forests: R. bahiensis ( Moricand 1839: 68) Kuntze (1891: 42) , R. guianensis Aublet (1775: 235) , R. laevigata (Solander en Gingins 1824: 314) Hekking (1988: 58), R. maximiliani ( Eichler 1871: 381) Kuntze (1981: 42) and R. ramiziana . All these species differ from R. gemmulata by presenting alternate leaves (versus opposite in R. gemmulata ) and lacking perulate buds. Except for R. laevigata , all other cited species have the stamens joined into a tube, in sharp contrast with the free stamens of R. gemmulata . Rinorea gemmulata and R. laevigata could be further differentiated by the thyrsoid inflorescence (versus racemose inflorescence in R. laevigata ), petals entirely pilose in both faces (versus glabrous or appressed pilose towards the apex) and fruit densely velutinous (versus glabrescent).

Figures

FIGURE 1. Rinorea gemmulata. A. Flowering branch. B. Leaf base highlighting the petiole and the base of the leaf blade pubescent. C–D. Scales from the perulate bud. E. Bractlet. F. Flower in anthesis. G–I. Sepals. J–K. Petals in dorsal (J) and ventral (K) views. L. Androecium after removing the petals, showing remnant sepals, the free stamens and pilose connectives. M. Stamen in dorsal view showing the pilose connectives. N. Stamen in ventral view showing the anther with two apical cusps subtended by the inner side of the connective scale. O. Gynoecium. P. Mature dehiscing capsule. A–O from Oliveira et al. 115; P from Carneiro-Torres et al. 1121. Drawn by Natanael Nascimento.

FIGURE 2. Rinorea gemmulata. A. Flowering branch showing the opposite leaves and the fasciculate inflorescences. B. Detail of the thyrsoid inflorescence highlighting the indeterminate main axis and lateral cymules. C. Detail of the inflorescence showing the cymules and flowers. D. Part of a branch apex showing a perulate bud (upper arrow) and some remnant scales (lower arrow). E. Mature fruits. A–D from Oliveira et al. 115; E from Carneiro-Torres et al. 1121. Photos by Luciano P. Queiroz.

FIGURE 3. Geographic distribution of Rinorea gemmulata in eastern Brazil.