(3021–3022) Proposals to conserve the names Brochoneura, with a conserved type, and Cephalosphaera (Myristicaceae)

(3021) Brochoneura Warb. in Engler, Pflanzenw. Ost-Afrikas C: 179. Jul 1895 [Myristic.], nom. cons. prop.

Typus: B. madagascariensis (Lam.) Warb. (in Nova Acta Acad. Caes. Leop.-Carol. German. Nat. Cur. 68: 234. Dec 1897) (Myristica madagascariensis Lam.), typ. cons. prop.

(3022) Cephalosphaera Warb. in Bot. Jahrb. Syst. 33: 383. 13 Mar 1903 [Myristic.], nom. cons. prop.

Typus: C. usambarensis (Warb.) Warb. (Brochoneura usambarensis Warb.).

Myristicaceae is a pantropical family of angiosperms comprising 21 genera and ca. 500 species. Recently, Figueiredo & Smith (in Phytotaxa 456: 299–300. 2020) proposed nomenclatural changes for the generic names Brochoneura and Cephalosphaera. Prior to their proposal, the name Brochoneura had been applied to a group of three species in Madagascar (Sauquet in Bot. J. Linn. Soc. 146: 351–368. 2004) whereas Cephalosphaera was exclusively applied to a single East African species. The proposed changes would have the name Brochoneura instead applied to the East African species while the Malagasy group would be renamed Neobrochoneura Figueiredo & Gideon F. Sm. This proposed name swap by Figueiredo & Smith followed their discovery of what may have been an unintentional name swap made by Otto Warburg, who originally published the name Brochoneura for the East African species (Warburg in Engler, Pflanzenw. Ost-Afrikas C: 180. 1895) and subsequently expanded the genus to incorporate three Malagasy species originally included in Myristica (Warburg in Nova Acta Acad. Caes. Leop.-Carol. German. Nat. Cur. 68: 237. 1897). Later, he published the monotypic East African genus Cephalosphaera (Warburg in Bot. Jahrb. Syst. 33: 383. 1903) for B. usambarensis, the original type of Brochoneura, while restricting Brochoneura to the Malagasy group. To rectify this centuries-old error by Warburg, the authors proposed to have Brochoneura reinstated for the monotypic East African genus and give the Malagasy group a new name, Neobrochoneura.

Although the name switch only affects a handful of species, it is nonetheless not helpful and may result in confusion, especially since the names in their pre-2020 sense have become well-established in the taxonomic and floristic literature. The name Brochoneura has been applied to the Malagasy group for well over a century whereas it had only been applied to the East African taxon for a mere eight years, namely from 1895 to 1903. Both genera also have important economic uses.

The East African Cephalosphaera (vernacular: mtambao) has historically been regarded as an economically valuable timber species, having been selectively logged since at least the mid-20th century (Waser & al. in Tanzania J. Forest. Nat. Conserv. 82(2): 42–49. 2013). In the 1960s, it was noted as “one of the most useful multi-purpose timber trees” and in the 1970s, the species became a “major source” of plywood, eventually leading to it being ranked eighth on the list of most important timbers of the East Usambara Mountains in 1985 (Lemmens & al. in Pl. Resources Trop. Afr. 7: 199. 2012).

The Malagasy Brochoneura (vernacular: mafotra, rara) has likewise been reported as an economically important group, with the species B. acuminata Warb. having uses ranging from construction to medicine (Bollen & Donati in Oryx 40: 1–10. 2006; Onjalalaina & al. in Forests 12(566): 1–20. 2021). The species B. acuminata is also known to have ecological significance. It is among the most abundant tree species encountered in the lowland tropical forests of eastern Madagascar, with an estimated density of 104 trees/ha recorded from southeast Madagascar (Campera & al. in Land (Basel) 12(81): 1–20. 2023). In addition, B. acuminata has been reported to serve as an important food source for several species of lemurs including the southern wolly lemur (Avahi meridionalis) and Mittermeier's sportive lemur (Lepilemur mittermeieri), the former of which utilizes the tree as its second most preferred food item during the lean season (Balestri, Ecology and Conservation of the Southern Woolly Lemur (Avahi meridionalis) in the Tsitongambarika Protected Area, South-eastern Madagascar [Ph.D. dissertation, Oxford Brookes University, Oxford]. 2018; Wilmet & al. in Lemur News 22: 26–30. 2020).

The names Brochoneura and Cephalosphaera appear widely in floristic literature and regional checklists (e.g., Ngumbau & al. in PhytoKeys 147: 1. 2020). In the scientific literature, the names continue to be applied in their pre-2020 sense, even after the publication by Figueiredo & Smith (e.g., Ndangalasi & al. in PLoS ONE 16(5): e0250859. 2021; Raharisoa & al. in J. Pharmacogn. Phytochem. 10: 104–109. 2021; Frost & al. in J. Biogeogr. 49(1): 156–170. 2022; Cheek & Luke in Kew Bull. 78: 469–497. 2023; and Lolila & al. in PLoS ONE 18(3): e0282528. 2023). This demonstrates the well-established nature of the names among researchers across multiple fields.

Therefore, we believe the sudden swapping of the application of Brochoneura to the Tanzanian species after more than a century of use for Madagascar species will only result in confusion among researchers, taxonomists, and conservation biologists working in Madagascar and East Africa. To preserve nomenclatural stability, the names Brochoneura and Cephalosphaera should be retained in their former sense. This can be achieved by conserving Brochoneura with a Madagacar species name (B. madagascariensis) as type and, conserving Cephalosphaera to make it legitimate, as Warburg included the original type of Brochoneura in the protologue of Cephalosphaera.