Aiouea ombrophila Brotto & Völtz, 2024

Brotto, Marcelo Leandro & Völtz, Rafael Rosenstock, 2024, Aiouea ombrophila (Lauraceae), a new large tree from the wet mountains of the Atlantic Rainforest, Brazil, Phytotaxa 669 (3), pp. 285-294 : 286-292

Aiouea ombrophila Brotto & Völtz , sp. nov. ( Figures 1 and 2 )

Type:— BRAZIL. Rio de Janeiro: Guapimirim, Parque Nacional da Serra dos Órgãos, trilha do pico Cabeça de Peixe , 22°27′59″S, 43°00′24″W, 1146 m, 2 December 2021, bud and fl., M.L. Brotto & R.R. Völtz 4784 (holotype MBM 440275!; isotypes HRCB 79552!, RB 869229!) .

Diagnosis:— Aiouea ombrophila is similar to Aiouea acarodomatifera Kostermans (1938: 67) , Aiouea albopunctata Brotto (2022: 389) , and Aiouea glaziovii (Mez 1889: 216) R.Rohde in Rohde et al. (2017: 1100), the latter being the most similar. The new species differs from A. glaziovii by leaves with longer petioles (1.5–2.6 vs. 0.8–1.5 cm long), pinnate to subtripliveined venation (vs. tripliveined), thinner midrib (0.4–0.8 vs. 0.8–1.0 mm thick), thinner first pair of secondary veins (0.2–0.4 vs. 0.5–0.7 mm thick), more secondary veins (7–9 vs. 4–6 pairs), ellipsoid fruits (vs. globose), and turbinate cupule (vs. obconic). Aiouea ombrophila also differs from A. acarodomatifera by having 4-locular anthers (vs. 2-locular), and turbinate cupule (vs. obconic), and from A. albopunctata by having pinnate to subtripliveined venation (vs. tripliveined) and a turbinate cupule (vs. hemispheric).

Description:—Canopy tree up to 30 m tall. Trunk cylindrical; bark pale-yellow, heterogeneous, both scaly and lenticellate, scales woody, adherent, rectangular or irregular, sometimes hanging from the trunk, lenticels round, small, numerous; slash bright-brown, tangential section homogeneous, not discolored, odorous, with a pleasant, moderately intense smell. Branches terete, brown, glabrous; branchlets slightly compressed, glabrescent; terminal buds puberulous. Leaves alternate, drooping; petioles 1.5–2.6 cm long, slightly canaliculate, glabrous; blades 5.7–15.0 × 3.0– 5.8 cm, oval-elliptic, broadly elliptic, elliptic or lanceolate, often arcuate, chartaceous; margin slightly undulate and thickened; base attenuate, rarely obtuse, apex acuminate, rarely short caudate, with acumen 0.5–1.5 cm long; adaxial surface glabrous, venation impressed, reticulation slightly dense, not ampullaceous at domatia; abaxial surface glabrous, midrib raised, 0.4–0.8 mm thick, secondary veins 7–9 on each side, first pair raised or slightly raised, 0.2–0.4 mm thick, 25–40° to midrib, other secondary veins slightly raised, 40–65° to midrib, reticulation somewhat dense, conspicuous; venation pinnate to subtripliveined, brochidodromous to weak eucamptodromous; domatia sometimes present, in the axils of the first pair of secondary veins, not sunken, covered with white hairs. Inflorescences axillary, paniculatecymose, 6.0–12.0 cm long, with up to 45 flowers, glabrous, rachis compressed. Flowers greenish in vivo, glabrous to glabrescent, 3.0– 3.5 mm diam.; pedicel 5.0–7.0 mm long; receptacle 1.0– 1.5 mm long, obconical, conspicuous, outside glabrous, inside puberulous to tomentose; tepals 6, subequal, oval-elliptic, erect at anthesis; whorl I 2.4–3.0 × 1.8–2.1 mm, outer surface glabrous to glabrescent, inner surface tomentose, minutely papillose at the tip; whorl II 2.6– 3.2 × 1.7–2.2 mm, outer surface glabrous, inner surface tomentose, minutely papillose at the tip; stamens 9, anthers 4-locular, filaments as long as the anthers or longer; whorl I 1.8–2.3 mm long, filament 0.9–1.3 mm long, tomentose, anther 0.9–1.1 × 0.6–0.8 mm, ovate-elliptic, apex obtuse, locelli introrse; whorl II 1.8–2.3 mm long, filament 0.9–1.5 mm long, tomentose, anther 0.8–1.1 × 0.5–0.8 mm, ovate-elliptic, apex obtuse, locelli introrse; whorl III 1.8–2.2 mm long, filament 1.1–1.4 mm long, tomentose, glands present at base, quadrangular-cordate, anther 0.7–0.8 × 0.4–0.6 mm, rectangular, apex truncate, upper locelli lateral, lower locelli lateral-extrorse; staminodes of whorl IV 1.4–1.6 mm long, filament tomentose, tip triangular-sagittate; pistil 2.5–3.0 mm long, glabrous, ovary globose ca. 1.0– 1.5 mm, style 2.5–2.8 mm, stigma simple. Fruits ellipsoid, 2.0 × 1.2 cm; cupules turbinate, 1.2 × 2.3 cm, covering 1/5 to 1/6 of the fruit, reddish in vivo, tepals deciduous.

Distribution and habitat:— Aiouea ombrophila is endemic to Brazil, occurring along the mountains of the Atlantic Coast between 22°16′S and 23°21′S, stretching from southern Minas Gerais to northern São Paulo and southeastern Rio de Janeiro. This species is a canopy tree in the Brazilian Atlantic Rainforest, commonly found in clayey soils within montane to upper montane forests between 950 to 2000 m elevation in the Serra do Mar and Serra da Mantiqueira mountains systems ( Figures 3 and 4 ). The slopes and mountain tops are frequently covered in mist or clouds ( Arcova 2013), and the region is characterized by high levels of annual rainfall that can reach the value of 1540 to 3300 mm ( Alvares et al. 2013, Brasiliense et al. 2020).

Conservation status:— Aiouea ombrophila is known from ten locations, all of which are located in legally protected areas, including Estação Ecológica Bananal, Parque Estadual da Serra do Mar–Núcleo Picinguaba and Núcleo Santa Virgínia, Parque Estadual dos Três Picos, Parque Nacional do Itatiaia, and Parque Nacional da Serra dos Órgãos. The calculated Extent of Occurrence (EOO) is 5580 km 2 and the Area of Occupancy (AOO) is 28 km ². According to the categories and criteria established by the IUCN (2024), the species would be classified as Vulnerable (VU) due to its limited extent of occurrence. However, it could also be considered Endangered (EN) since its area of occupancy is less than 500 km ². To be classified as EN the species would require five or fewer locations [B(a)]. We propose that A. ombrophila should be classified as Vulnerable (VU B1,B2,a,bii,biii). Despite occurring in legally protected areas, its limited extent of occurrence in a specific mountainous environment must be considered, as the two most extreme locations are only 292 km apart.

Phenology:—Flowering specimens were collected in December; fruiting specimens were collected from December to July.

Etymology:—The name ‘ombrophila’ is given to this new species due to its natural habitat. It grows in the moist forests of the Serra do Mar and Serra da Mantiqueira mountain ranges, which are often covered by mist or clouds and receive high levels of rainfall annually. The term ‘ombrophilous’ means that this species is capable of withstanding or thriving in the presence of much rain.

Paratypes:— BRAZIL. Minas Gerais: Bocaina de Minas, Parque Nacional do Itatiaia, Alto dos Brejos, August 2004, st., L. Schumm 20 (RB 438088!). São Paulo: Bananal , Estação Ecológica Bananal , trilha da Pedra Vermelha, 12 February 2002, im. fr., P.L.R. de Moraes 2533 (ESA 76796!, SPSF 32899). Paraibuna , ‒ 23.3520S, ‒ 45.3213W, 30 June 2011, st., E. Stefani Jr. 255 (UEC 166975!). São Luiz do Paraitinga , parcela K, 2008, st., M.C.G. Padgurschi 1069 (UEC 166737!) ; ibidem, 2008, st., M.C.G. Padgurschi 1507 (UEC 166760!); ibidem, 23°19′31″S, 45°04′10″W, 1035 m, 12 December 2021, im. fr., M.L. Brotto & R.R. Völtz 4805 (HRCB 79553!, MBM 440276!, RB 869227!). Ubatuba, Picinguaba, 23°22′S, 44°48′W, 16 April 1997, fr., F. Pedroni 656 (UEC 166257!). Rio de Janeiro: Guapimirim, Parque Nacional da Serra dos Órgãos, trilha do pico Cabeça de Peixe , 22°27′59″S, 43°00′24″W, 1142 m, 9 February 2021, im. fr., M.L. Brotto & R.R. Völtz 4115 (HRCB 79555!, MBM 432175!) ; ibidem, 22°28′00″S, 43°00′20″W, 1010 m, 12 July 2021, im. fr., M.L. Brotto & R.R. Völtz 4326 (HRCB 79557!, MBM 432244!, RB 869228!); Teresópolis, Parque Estadual dos Três Picos , Vale da Revolta , 22°26′51″S, 42°56′37″W, 1055 m, 16 June 2022, im. fr., M.L. Brotto & R.R. Völtz 5123 (HRCB 79556!, MBM 440277!, RB 869226!) ; Parque Nacional da Serra dos Órgãos , trilha do riacho fundo, 22°27′23″S, 42°59′57″W, 1236 m, 28 June 2007, fr., M. Nadruz et al. 1914 (RB 441973!) ; ibidem, Matas do Rio Paquequer, próx. ao km 2,0 da Estrada para Barragem ca. 1125 m, 14 December 2003, st., C. S. Pardo 465 (RB 423625!, RB 426964!) .

Aiouea ombrophila fits the genus concept proposed by Rohde et al. (2017). This includes flowers with 9 fertile stamens, occasionally 6 or 3, and anthers that are 4-locular or 2-locular. The new species has 9 fertile stamens and

4-locular anthers. Previously, only species with 2-locular anthers belonged to the genus. The others with 4-locular anthers were formerly classified under the Neotropical Cinnamomum .

Among the Brazilian species inhabiting the Atlantic Rainforest, the new species is most similar to Aiouea glaziovii ( Table 1). Both are large trees and sympatric in the Serra do Mar mountainous region. Aiouea ombrophila differs by having a longer petiole (1.5–2.6 mm), lower leaf surface glabrous, pinnate to subtripliveined venation, midrib and secondary veins impressed on adaxial surface, midrib (0.4–0.8 mm diam.) and first pair of secondary veins (0.2–0.4 mm diam.) raised on the abaxial surface, puberulous to tomentose inner receptacle, ellipsoidal fruit, and turbinate cupule covering 1/5 to 1/6 of the fruit. In contrast, Aiouea glaziovii has a shorter petiole (0.8–1.5 mm), lower leaf surface sparsely pubescent, tripliveined venation, midrib and first pair of secondary veins immersed on adaxial surface, midrib (0.8–1.0 mm diam.) and secondary veins (0.5–0.7 mm diam.) raised on the abaxial surface, glabrous inner receptacle, globose fruit, and obconic cupule that does not cover the fruit.

The new species also resembles Aiouea acarodomatifera ( Table 1). Both are sympatric but can be readily differentiated by the larger size of the tree and leaves of Aiouea ombrophila . However, the main difference is the number of pollen sacs, which is 4 on anthers of A. ombrophila and 2 on anthers of A. acarodomatifera . Other distinguishing characters include the pale-yellow rhytidome with woody scales, longer petioles (1.5–2.6 mm), 7–9 pairs of secondary veins on the leaves, and a turbinate cupule. Aiouea acarodomatifera has a gray rough rhytidome without scales, shorter petioles (0.5–1.4 mm), 5–8 pairs of secondary veins on the leaves, and an obconic cupule.

Aiouea albopunctata is another species similar to A. ombrophila ( Table 1). Both are large trees up to 30 m tall, with leaves having a similar venation pattern, inflorescences, and flowers of equivalent size, and similar floral parts, with 4-locular anthers. However, A. ombrophila differs by its pale-yellow rhytidome with woody scales, slightly wider leaves and longer petioles, pinnate to subtripliveined blades, impressed midrib on the adaxial surface, ovate-elliptic anthers of whorls I and II, and turbinate cupules covering 1/5 to 1/6 of the fruits. Aiouea albopunctata has a greyishbrown fissured-scaly rhytidome, narrower leaves, shorter petioles, always tripliveined blades, immersed midrib at the base on the adaxial surface, rectangular-ovate anthers of whorls I and II, and hemispheric cupules covering 1/3 to 1/4 of the fruits. Furthermore, these species are parapatric, except for an encounter in Parque Nacional do Itatiaia. Aiouea ombrophila is distributed in the mountains closest to the Atlantic Ocean, which receive the greatest amount of rainfall, while A. albopunctata is distributed further west, under the influence of a more seasonal climate with less annual rainfall.

Some paratypes were previously identified as Ocotea divaricata ( Nees von Esenbeck 1836: 467) Mez (1889: 385) and Ocotea notata (Nees & Mart. in Nees von Esenbeck 1833: 42) Mez (1889: 339) due to the similarity in blade shape and venation. However, they are easily distinguished by their flowers and fruits. Both Ocotea species have filiform staminodes of the fourth whorl or none, while the new species has well-developed staminodes with triangular-sagittate heads. The two Ocotea species have globose or ovoid fruits and different cupules: obconic with hexalobed margins in Ocotea divaricata , patelliform or hemispheric in Ocotea notata . In contrast, Aiouea ombrophila has ellipsoid fruits and turbinate cupule with simple margins. Additionally, both Ocotea species are small or medium-sized trees.

Figures

FIGURE 1. Aiouea ombrophila Brotto & Völtz. A. Flowering branch. B. Broadly-elliptic leaf (abaxial surface). C. Oval-elliptic leaf (abaxial surface). D. Lanceolate leaf (abaxial surface). E. Flower. F. Abaxial tepal surface whorl I. G. Abaxial tepal surface whorl II. H. Adaxial tepal surface whorl I. I. Adaxial tepal surface whorl II. J. Adaxial stamen surface whorl I. K. Abaxial stamen surface whorl III. L. Adaxial staminode surface whorl IV. M. Pistil. N. Cupule and fruit (A–C, E–M, Brotto 4784; D and N, Brotto 5123).

FIGURE 2. Aiouea ombrophila Brotto & Völtz. A. Fruiting branch. B. Leaf (abaxial surface). C. Inflorescence. D. Flower at anthesis. E. Flowers at anthesis. F. Flower at anthesis. G. Fruit in the initial stage of development. H. Fruit in the final stage of development. I. Rhytidome of a thick trunk. J. Detail of rhytidome. Photographs by M.L. Brotto (vouchers A, G, Brotto 4805; B, H–J, Brotto 5123; C–F, Brotto 4784).

FIGURE 3. Location of Aiouea ombrophila Brotto & Völtz types in Serra dos Órgãos mountain range: Cabeça de Peixe peak in high point of view (A) and low point of view (B). Holotype above (voucher Brotto 4784), and paratype below (voucher Brotto 4326).

FIGURE 4. Distribution map of Aiouea ombrophila Brotto & Völtz. Legend: ES—Espírito Santo; MG—Minas Gerais; RJ—Rio de Janeiro; and SP—São Paulo.