Euphorbia confertiflora Volkens, 1899

Figueiredo, Estrela & Smith, Gideon F., 2020, Typification of Euphorbia candelabrum (Euphorbiaceae) and associated names, Phytotaxa 447 (3), pp. 216-220 : 219

Status of Euphorbia confertiflora Volkens and Euphorbia reinhardtii Volkens

There has been some confusion in the literature regarding the types of the names E. confertiflora and E. reinhardtii , both of which were published by Volkens (1899). Bruyns & Berry (2019: 837) incorrectly cited E. confertiflora as a ‘nom. illeg. superfl.’ homotypic with E. reinhardtii , both with the type ‘ Holst 8821 (B, destroyed)’. According to the protologue of E. confertiflora the name was based on spirit-preserved material collected by Holst under the number 8821. Volkens (1899) stated that the number also included material of E. reinhardtii , i.e., two specimens existed under number 8821 and they were interpreted by Volkens as representing separate species.

Carter & Gilbert (1987) synonymised E. confertiflora with E. heterochroma Pax (1895: 242) citing two syntypes, but excluding one of them: ‘Volkens s.n., excl. Holst 8821 (syntypes B†)’. In fact there was no mention of any preserved specimen by Volkens (1899), and only Holst 8821 pro parte is the known original material. Later, Carter (1988) synonymised E. confertiflora with E. candelabrum Trémaux ex Kotschy instead, then correcting the type citation to: ‘Holst 8821, partly (B, holo.†)’. Carter (1988) postulated that the part of 8821 used to produce the description was juvenile material of the same taxon as the remaining part of 8821. As noted by Carter (1988) and confirmed at Herb. B (Robert Vogt, pers. comm.) this spirit material is no longer extant, thus it is not possible to verify this hypothesis.

For E. reinhardtii , the protologue includes the citation of the same spirit collection, Holst 8821, but also material collected by Volkens in East Africa and preserved in spirit. Carter (1987) synonymised E. reinhardtii with E. candelabrum Trémaux ex Kotschy , incorrectly citing as type: ‘Holst 8821 (holotype B†)’, later correcting it to ‘Holst 8821, partly (B, holo.†)’ ( Carter 1988). However, as Volkens (1899) clearly mentioned two distinct collections in the protologue, there is no holotype for E. reinhardtii , and the type material is rather: Holst 8821 pro parte (B, syn- †) and Volkens s.n. (B, syn- †). None of this material is extant at Herb. B (Robert Vogt, pers. comm.). The two names were not based on the same type and they are not homotypic: E. confertiflora is based on Holst 8821 pro parte and E. reinhardtii is based on both Holst 8821 pro parte and Volkens s.n. Therefore, the name Euphorbia confertiflora is not an illegitimate name.