Oxypetalum Brown 1810
Creators: name: Rapini, Alessandro
name: Pereira, Jorge Fontella
name: Goyder, David J.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Gentianales
Apocynaceae
Oxypetalum

description: Oxypetalum Brown (1810: 30), nom. cons.
Type: O. banksii Schultes (1820: 91).
Gothofreda Ventenat (1808: t. 60), nom. rej.
Schistogyne Hooker & Arnott (1834: 291). Type: S. sylvestris Hooker & Arnott (1834: 292). Synon. nov.
Calostigma Decaisne (1838: 343). Type: C. insigne Decaisne (1838: 344; t. 12, f. H).
Schizostemma Decaisne (1838: 344). Type: non designatus.
Pachyglossum Decaisne (1838: 345). Type: non designatus.
Bustelma Fournier (1885: 287). Type: B. warmingii Fournier (1885: 287).
Dactylostelma Schlechter (1895: 452). Type: D. boliviense Schlechter (1895: 452).
Corollonema Schlechter (1914: 441). Type: C. boliviensis Schlechter (1914: 441).
Amblyopetalum Malme (1927: 2). Type: A. coccineum (Grisebach 1874: 206) Malme (1937: 8).
Metoxypetalum Morillo (1994: 145). Type: M. retusum (Markgraf 1933: 787) Morillo (1994: 146).
Note:— Oxypetalum is the largest genus of Oxypetalinae, including around 120 species, distributed from Argentina to Mexico, with the centre of diversity in central-eastern South America. Most species are characterised by a combination of flowers with lanceolate corolla lobes, corona lobes gynostegial in origin but displaced onto the base of the corolla, free above and adaxially ornamented, style-head forming a rostrate appendage at the apex of gynostegium simulating a stigma, and caudicles of pollinaria with lateral teeth. Schistogyne was created based on the unusual appendage of the style-head with seven linear lobes in S. sylvestris: ‘ Stygma sub-7-partitum (!), segmentis subulato-filiformis.’ (Hooker & Arnott 1834: 292), and with gynostegial corona lobes in a staminal position. Variations of the style-head appendage were used to recognise some genera currently considered synonym of Oxypetalum (e.g., Calostigma). Nevertheless, this is a polymorphic structure and variations are found even in closely related species. For instance, O. pilosum Gardner (1842: 539) exhibits style-head terminating in a rostrate appendage, whereas O. erostre Fournier (1885: 265), which is the closest species and was eventually considered synonym of the former (Valente et al. 1973), exhibit a conical style-head lacking an appendage.
Besides confirming the inclusion of Amblyopetalum, Bustelma and Dactylostelma in the synonymy of Oxypetalum, phylogenetic studies of plastid regions (Rapini et al. 2003, Liede-Schumann et al. 2005) also showed Schistogyne nested in core Oxypetalum, closely related to O. banksii. To become monophyletic, Oxypetalum must include Schistogyne. Below, we provide the combinations for the eight accepted species of Schistogyne in Oxypetalum, designate lectotypes for three species and indicate a new synonym.
description: Published as part of Rapini, Alessandro, Pereira, Jorge Fontella & Goyder, David J., 2011, Towards a stable generic circumscription in Oxypetalinae (Apocynaceae), pp. 9-16 in Phytotaxa 26 on page 12, DOI: 10.11646/phytotaxa.26.1.2, http://zenodo.org/record/4894142