Revision of the genus Benthamia A.Rich. (Orchidaceae, Orchidioideae, Habenariinae)

A revision of the genus Benthamia A.Rich is presented, based on herbarium material, literature and field observations. A taxonomic history of the genus is given. Thirty-one species are recognized and described. Seven new species are described: Benthamia litoralis Hervouet & Descourv., sp. nov., Benthamia decaryana Descourv. & Hervouet, sp. nov., Benthamia lakatoensis Descourv. & Hervouet, sp. nov., Benthamia mascula Hervouet & Descourv., sp. nov., Benthamia trifida Hermans & Hervouet, sp. nov., Benthamia corona Hermans & Hervouet, sp. nov., Benthamia vulcanorum Hervouet & Descourv., sp. nov. A new form is established: Benthamia erinacea (Cordemoy) Hermans & P.J.Cribb f. reticulata Hervouet & Descourv., f. nov. One subspecies is raised to species level: Benthamia herminioides subsp. arcuata H.Perrier becomes Benthamia arcuata (H.Perrier) Descourv. & Hervouet, comb. nov., stat. nov., seven taxa are reduced to synonymy: Benthamia herminioides subsp. angustifolia H.Perrier is a synonym of Benthamia perfecunda H.Perrier, Benthamia verecunda Schltr. and Benthamia nigrovaginata H.Perrier are synonyms of Benthamia elata Schltr., Benthamia exilis var. tenuissima Schltr. is a synonym of Benthamia exilis Schltr., Benthamia herminioides subsp. intermedia is a synonym of Benthamia herminioides Schltr., Benthamia nivea subsp. parviflora H.Perrier is a synonym of Benthamia nivea Schltr., Benthamia perularioides Schltr. is a synonym of Benthamia rostrata Schltr. Two species remain undescribed because they are known only from photographs, four specimens are discussed for their specific interest and are potentially new species but this remains to be confirmed when more data becomes available. Twelve taxa are lectotypified: B. calceolata H.Perrier, B. elata Schltr., B. exilis var. tenuissima Schltr., B. nigrovaginata H.Perrier, B. verecunda Schltr., B. nigrescens subsp. borbonica H.Perrier, B. nigrescens subsp. humblotiana, B. catatiana, B. humbertii H.Perrier, B. melanopoda Schltr., B. perularioides Schltr., B. praecox Schltr. Three species, Benthamia dauphinensis (Rolfe) Schltr., Benthamia macra Schltr. and Benthamia misera (Ridl.) Schltr., are considered ambiguous or insufficiently known. Benthamia longecalceata H.Perrier, is excluded, being a synonym of Cynorkis falcata (Frapp.) Schltr. Benthamia micrantha (Frapp. ex Cordem.) Hermans & Hervouet (nom. illeg.) is excluded, being Cynorkis micrantha (Frapp. ex Cordem.) Schltr. The relationship with other genera is investigated and several groups of similar species within the genus Benthamia are proposed as a starting point for a subgeneric classification.

Distribution map