Hornschuchia (Annonaceae), an endemic and threatened genus from the Brazilian Atlantic Forest Author Vilela, Lucas Universidade de São Paulo, Instituto de Biociências, Departamento de Botânica, Rua do Matão, 277, ed. Sobre-as-Ondas, 05508 - 090 São Paulo, SP, Brazil. & Universidade Anhembi-Morumbi, Escola de Ciências da Saúde, Rua Dr. Almeida Lima, 1134, 03101 - 001, Mooca, São Paulo, SP, Brazil. vilela.lucas@hotmail.com Author Lopes, Jenifer De Carvalho Universidade de São Paulo, Instituto de Biociências, Departamento de Botânica, Rua do Matão, 277, ed. Sobre-as-Ondas, 05508 - 090 São Paulo, SP, Brazil. jenifer.clopes@gmail.com text European Journal of Taxonomy 2022 2022-07-11 828 75 108 http://dx.doi.org/10.5852/ejt.2022.828.1859 journal article 10.5852/ejt.2022.828.1859 c5427427-07fc-4449-ba86-25f19cd47482 2118-9773 6823766 Genus Hornschuchia Nees Flora 4 (1): 302 ( Nees 1821 ) . − Type species: Hornschuchia bryotrophe Nees. Mosenodendron R.E.Fr., Kongliga Svenska Vetenskaps Akademiens Handlingar , ser. 3 34 (5): 8 ( Fries 1900 ) . Type species: Mosenodendron insigne R.E.Fr. Description Trees to shrubs. Leaves chartaceous to coriaceous with primary vein impressed adaxially. Inflorescence 1-flowered or 2–22-flowered; axillary, supra-axillary, terminal or cauliflorous, i.e., ramiflory, trunciflory, flagelliflory. Flowers white, rarely pinkish, trimerous; three sepals and six petals in two whorls; calyx with sepals completely connate, rarely connate at the base; corolla with linear petals; stamens 3–18; carpels 2–9. Fruit with 1–5 monocarps, monocarps obovate, globose, ellipsoid, obloid, fusiform; stipe 1.5–9 mm long, subsessile to sessile. Seed 1–8, globose, obovoid, obloid-ellipsoid, ellipsoid, flattened-ellipsoid, with aril, rarely without aril. Hornschuchia is recognized by its small and white flowers, with linear petals and cupuliform calyx. It is similar to Trigynaea and Bocagea ; however, the petals in these two genera are ovate, elliptic or lanceolate ( Johnson & Murray 1995 ). Key to the species of Hornschuchia Nees 1. Leaves with commissural veins evident ............................................................. H. bryotrophe Nees − Leaves without commissural veins ................................................................................................... 2 2. Inflorescence axillary, supra-axillary to terminal or ramiflorous ...................................................... 3 − Cauliflorous, except ramiflorous ......................................................................................................11 3. Inflorescence 1-flowered ................................................................................................................... 4 − Inflorescence 2–22-flowered ........................................................................................................... 10 4. Calyx connate at the base with triangular apex ....................................... H. citriodora D.M.Johnson − Calyx completely connate (cupuliform) with truncate apex ............................................................. 5 5. Calyx 3–8 mm long .......................................................................................................................... 6 − Calyx 1–2(–3) mm long .................................................................................................................... 8 6. Stamens 10, 4 mm long, carpels 5.5 mm long. Monocarp obloid with acute apex, 20–24 × 9–12 mm , stipe 1–2 mm long .................................................................... H. mellosilvae L.Vilela & J.C.Lopes − Stamens 3–6, 2–3 mm long, carpels 2–3 mm long. Monocarp globose to ellipsoid with rounded apex, 8–13 × 5–9 mm , sessile .................................................................................................................... 7 7. Floral bud cylindrical with obtuse apex. Fruit 1 monocarp with persistent calyx .............................. .................................................................................................................. H. lianarum D.M.Johnson − Floral bud globose to ovoid to conical with acute apex. Fruit 2–5 monocarps with caducous calyx ... .................................................................................... H. mediterranea Mello-Silva & D.M.Johnson 8. Calyx glabrescent. Monocarp sessile ................................................................... H. polyantha Maas − Calyx densely covered in trichomes. Monocarp stipe 1.5–3 mm long ............................................. 9 9. Leaves narrowly elliptic to elliptic, oblanceolate to narrowly oblong, obovate or rarely lanceolate. Pedicel 7–37 mm long ............................................................................................ H. myrtillus Nees − Leaves narrowly ovate to ovate or lanceolate. Pedicel 1–7 mm long ..... H. alba (A.St.-Hil.) R.E.Fr. 10. Floral bud cylindrical. Monocarp fusiform, 5–8 mm wide, densely covered in trichomes, whitish in vivo ........................................................................................................... H. obliqua Maas & Setten − Floral bud conical. Monocarp globose, 16–19 mm wide, glabrous, green in vivo ............................ ..................................................................................................................... H. santosii D.M.Johnson 11. Trunciflory ...................................................................................................................................... 12 − Flagelliflory, i.e., inflorescence branches 4.5–100 cm long, emerging from the basal part of the trunk and running near the soil ................................................................................................................. 13 12. Inflorescence branches 6–19 cm long ...................................................... H. leptandra D.M.Johnson − Inflorescence emerging close to the trunk ............................................. H. cauliflora Maas & Setten 13. Calyx glabrescent. Bracts caducous .................................................................... H. polyantha Maas − Calyx densely covered in trichomes. Bracts persistent .......................................... H. myrtillus Nees