Siphoneugena itatiaiensis D.K.Caldas & Stadnik, 2025

Caldas, Diana K. D., Stadnik, Aline M. S., Souza, Marcelo Da C., Do Rosário, Alessandro S. & Baumgratz, José Fernando A., 2025, A new species of Siphoneugena and a new combination in Plinia (Myrtaceae), Phytotaxa 683 (1), pp. 79-86 : 80

Siphoneugena itatiaiensis D.K.Caldas & Stadnik , sp. nov. ( Figs. 1, 2 ).

Type:— BRAZIL. Rio de Janeiro: municipality of Itatiaia, Parque Nacional de Itatiaia (22° 15’– 22° 28S and 44° 34’– 45° 45’W), Taquaral , encosta à direita (descendo) do rio Campo Belo. Alt. 660 a.s.l., 20/07/1995, fl., J. M. A. Braga et al. 2538 (holotype RB [barcode RB00476656 !]; isotype BHCB [barcode BHCB013940 ], image!) .

Diagnosis:— Siphoneugena itatiaiensis is morphologically close to S. densiflora , but differs mainly in the oblong leaf blades (vs. elliptic in S. densiflora ), hypanthium not constricted above the ovary (vs. constricted above the ovary), flowers buds tomentose (vs. glabrous), sessile (vs. pedicellate) and 3 ovules per locule (vs. 4–5 ovules).

Description:—Treelets ca. 3.5 m tall. Bark thin, exfoliating (fide type specimen), bark of old branches striate. Indumentum of golden shaggy trichomes, present on young branches, adaxial surface of the leaves along the midvein, bracts, bracteoles, flower buds, hypanthium, calyx lobes and petals. Young branches terete. Leaves with petioles 1–3 × 0.3–0.5 cm, canaliculate, glabrous; blades 9–11 × 3.5–4 cm, chartaceous, oblong, glabrous on both sides; base attenuate; apex cuspidate; venation brochidodromous, midvein raised on both sides, secondary veins 23–27 at each side, leaving the midvein at angles 65°–75°, raised on both sides, marginal vein ca. 1 mm from the margin; pellucid gland dots ca. 0.1 mm diam., 1–2 dots per mm². Inflorescences glomerate, ramiflorous, with 4–6 flowers; bracts 4, 2–3 × 1–1,5 mm, elliptic; bracteoles 2, 6–8 × 3–4 mm, ovate or elliptic, ciliate, persistent. Flower buds obovate, 7–12 × 8–10 mm, sessile, densely tomentose; hypanthium extended above the ovary, 4– 3 mm long, not constricted above the ovary, tearing during anthesis, deciduous; calyx lobes 4, 1–2 × 1–1,5 mm, partially fused, tearing irregularly at anthesis, pilose on both sides; petals 4, 5–8 × 2–5 mm; stamens with filaments 5–7 mm long after anthesis, anthers 0.4–0.7 × 0.3–0.4 mm, oblong or elliptic, rimose, connective eglandular, glabrous; style 7–12 mm long after anthesis, glabrous, stigma punctiform; ovary 2-locular, 3 ovules per locule. Fruits not seen.

Phenology:— Siphoneugena itatiaiensis was collected flowering in July.

Etymology:—The specific epithet refers to the place of collection, the municipality of Itatiaia.

Distribution and habitat:— Siphoneugena itatiaiensis is known from Dense Ombrophilous Forest in the Itatiaia National Park, in the municipality of Itatiaia, Rio de Janeiro, Brazil ( Figs. 3 , 4 ).

Conservation status:— Siphoneugena itatiaiensis is known from only a single collection with two specimens ( RB and BHCB), from the municipality of Itatiaia. Currently, given the lack of sufficient information to make an assessment, directly or indirectly, of the risk of extinction based on its distribution and/or population status, this species can be considered as Data Deficient ( DD; IUCN 2019 ) .

Comments:—Following the new classification of Pliniinae proposed by Stadnik (2020), the new species belongs to the genus Siphoneugena , characterized by a foliar blade with prominent primary ribs on the adaxial surface, glomeruliform inflorescences ( Fig. 1 B), expansion and rupture of the hypanthium during anthesis, deciduous calyx lobes partially fused in the bud, and ovaries with 3–5 ovules per locule.

Figures

FIGURE 2. Isotype of Siphoneugena itatiaiensis at BHCB. A. branch; B. inflorescence.

FIGURE 3. Map with geographic distribution of Siphoneugena itatiaiensis.

FIGURE 4. Habitats of Siphoneugena itatiaiensis inItatiaia National Park, Rio de Janeiro—a:Vegetation of Montane OmbrophilousDense Forest cut by the Maromba River, in the lower part of the Park; b) field vegetation between formation of High Montane Ombrophilous Dense Forest, in the upper part of the Park.