Hornschuchia alba
Creators: name: Vilela, Lucas
name: Lopes, Jenifer De Carvalho
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Magnoliales
Annonaceae
Hornschuchia
Hornschuchia alba

description: Hornschuchia alba (A.St.-Hil.) R.E.Fr.
Fig. 1
Acta Horti Bergiani 10 (2): 137 (Fries 1931).
Basionym
Bocagea alba A.St. -Hil., Flora Brasiliae meridionalis 1 (2): 42 (Saint-Hilaire 1825).
Type: BRAZIL – Rio de Janeiro • “ Cabo Frio, Ponta de lʼEst au Cap Frio, Prov. Rio de Janeiro ”; A. Saint-Hilaire 366; holotype: P [P032535]!; isotypes: MPU [MPU026907]!, S [S-R-7077]! (fragment).
Material examined
BRAZIL – Rio de Janeiro • “ Armação dos Búzios, Praia Brava. Mata de Encosta Sul voltada para o costão da Praia Brava ”; 24 May 2001; C. Farney 4371; RB [RB00451923]!, SPF! • “ Costão para João Fernandes. Mata de encosta Praia Brava- Costão para João Fernandes ”; [22°44′38.5″ S, 41°52′17.8″ W]; 23 Aug. 2001; C. Farney 4397; RB [RB00452010]!, SPF! • “ Encosta da Praia Brava ”; 22°44′92″ S, 41°52′40″ W; 18 Feb. 2004; H.G. Dantas 620; RB [RB00086462]! • ibid.; 22°44′92″ S, 41°52′40″ W; 18 Feb. 2004; H.G. Dantas 156; RB [RB00086467]! • “ Rancho Dez ”; Jun. 1997; C. Farney s.n.; RB [RB00372099]! • “ Fazenda Caravelas ”; alt. 80 m; 20 Oct. 1999; C. Farney 3930; SPF!, RB [00452151]! • “ Estrada Cabo Frio- Búzios, entre a Serra das Esmerencias e a Praia de José Gonçalves ”; [22°48′32.8″ S, 41°56′37.8″ W]; 5 Jun. 1998; J.M.A. Braga 4871; RB [RB00042085]! • “ Fazenda of José Gonçalves ”; 22°47′ S, 41°57′ W; alt. 120 m; 8 Feb. 1999; P.J. Maas 8818; NY [NY02699049]!, RB [RB00042092]!, SPF! • “ Estrada antiga para Búzios, próximo ao centrinho, ramal da lixeira ”; 28 Jun. 1995; D. Araújo 10320; RB [RB00417332]! • “ Cabo Frio, Morro da Piaçava ”; 9 Oct. 2002; C. Farney 4487; SPF!, RB [RB00451944]! • “ Morro do Mico ”; [22°51′45.4″ S, 42°00′38.5″ W]; 22 Jun. 2002; C. Farney 4463; RB [RB00451806]!, SPF! • 27 Aug. 1997; C. Farney 3587; CEPEC [CEPEC00118741]!, MBM [MBM325079]!, R [RB00043047]!, SPF!. – Locality unknown • “ E Brasilia ”; Freyreis s.n.; S n.v.
Description
Shrubs, rarely treelets, 2–7 m tall. Leaves chartaceous; petiole 1–3 mm long; lamina 3.8–9.3 × 1.9–4.9 cm, narrowly ovate to ovate or lanceolate, both surfaces glabrous, base acute to obtuse, apex acuminate to acute, obtuse or rounded; primary vein impressed adaxially and raised abaxially, 6–12 pairs of secondary veins, angles between primary and secondary veins 50–60°. Inflorescence one-flowered; supra-axillary, terminal or leaf-opposed, bracts absent. Flowers with pedicel 1–7 mm long; flower buds conical to cylindrical with obtuse apex, 2–8 × 1–3 mm, covered in trichomes. Sepals completely connate, calyx cupuliform, apex truncate, 2 × 2–3 mm, densely covered in trichomes. Petals linear, white, 11–14 mm long, covered in trichomes; stamens 6, ca 2 × 0.5 mm; carpels 3, ca 3 × 0.5 mm. Monocarps 2, immature monocarps fusiform, 4–9 × 3 mm, densely covered in trichomes, mature monocarps obovate, ca 2 cm long (Saint-Hilaire 1825); stipe ca 1.5 mm long, calyx persistent. Seed ca 6 mm long, ellipsoid, reddish, with fleshy aril (Saint-Hilaire 1825).
Distribution and habitat
Hornschuchia alba is endemic to Rio de Janeiro State. It is known from only two municipalities, Armação de Búzios and Cabo Frio, occurring in seasonal semideciduous lowland forest (Mello-Silva et al. 2021; Fig. 1).
Phenology
Flowering from February to October, fruiting from September to October.
Preliminary conservation status
Critically Endangered, CR B1ab(i,ii,iii) (Amaro 2016). At the time of the last revision of the genus (Johnson & Murray 1995), only two historical collections of H. alba, including the type, were available. The species was only known with certainty from Cabo Frio. Nowadays there are eight localities, in Armação de Búzios and Cabo Frio, where the species is known to occur. However, H. alba has not been collected in 18 years.
Notes
Johnson & Murray (1995) indicated the holotype as Saint-Hilaire 99. However, this collection number has been assigned to a species of Amaranthaceae Juss. The holotype of Bocagea alba is in fact Saint-Hilaire 366 (Saint-Hilaire’s field notebooks are available at http://hvsh.cria.org.br/works).
There are only immature fruits available (Farney 3930 and 4487), the fruit and seed descriptions have been complemented with the information in Saint-Hilaire (1825). With the new collections of H. alba, the description of the species has been updated (Johnson & Murray 1995) with new information about the habit and plant size, inflorescence position and flower dimension.
Hornschuchia alba has a single-flowered inflorescence, supra-axillary, terminal or leaf-opposed. It is similar to the specimens of H. myrtillus with this type of inflorescence. However, H. alba is different from H. myrtillus in the leaves that are narrowly ovate to ovate or lanceolate (vs narrowly elliptic to elliptic, oblanceolate to narrowly oblong, obovate or rarely lanceolate) and the pedicel 1–7 mm long (vs 10–28 mm long).
description: Published as part of Vilela, Lucas & Lopes, Jenifer De Carvalho, 2022, Hornschuchia (Annonaceae), an endemic and threatened genus from the Brazilian Atlantic Forest, pp. 75-108 in European Journal of Taxonomy 828 on pages 79-80, DOI: 10.5852/ejt.2022.828.1859, http://zenodo.org/record/6823766