Melocactus pachycephalus

Guiggi, Alessandro & Mariotti, Mauro, 2021, Nomenclatural remarks in the genus Melocactus (Cactaceae, Cereeae) from NE Brazil, Phytotaxa 496 (1), pp. 97-100 : 97

Melocactus pachycephalus

In a recent nomenclatural work concerning the Brazilian cacti belonging to the tribe Cereeae Salm-Dyck ( Taylor & Zappi 2020: 256–258) , Melocactus pachycephalus nomen novum, based on M. pachyacanthus Buining & Brederoo (1975: 1) subsp. viridis N.P. Taylor (1991: 40) was proposed at specific level to replace the illegitimate M. viridescens Guiggi (2020a: 3) . The latter name is, in fact, a later homonym (and illegitimate according to the Art. 53.1 of ICN; see Turland et al. 2018) of M. viridescens ( Torrey & Gray 1840: 554) Nuttall ex Teschemacher (1845: 293) . Nevertheless, Guiggi (2020b: 2) have been noticed his nomenclatural error and already proposed a new name, i.e. Melocactus neoviridescens . The complete taxonomic treatment follows.

Melocactus neoviridescens Guiggi (2020b: 2) , nom. nov. pro. Melocactus pachyacanthus N.P. Taylor (2020: 256) subsp. viridis N.P. Taylor (1991: 40) non M. viridis Lawrence (1841: 319) ≡ Melocactus viridescens Guiggi (2020a: 3) , nom. illeg. (Art. 53.1 of ICN), non M. viridescens ( Torrey & Gray 1840: 554) Nuttall ex Teschemacher (1845: 293) ≡ Melocactus pachycephalus N.P. Taylor (2020: 256) , nom. superfl. et illeg. (Art. 52.1 of ICN).

Type: ― BRAZIL. Bahia: Mun. América Dourada, 2 Km W Campo Belo (Belo Campo), 750 m, 26 December 1988, Harley, Taylor & Zappi 27400 (holotype CEPEC, non videmus; isotypes SPF, non videmus, K000013184 !, three sheets, corp, ceph, ar, sp, Fig. 1 ; image of the K isotype at available http://specimens.kew.org/herbarium/ K000013184 ) .

Etymology: ―From Greek ‘neos’ new (to avoid a homonym) and Latin ‘ viridescens ’ to be green referred to the colour of the epidermis (Eggli & Newton 2004: 164, 253).

Notes on the taxonomy of Melocactus neoviridescens :―This taxon was elevated at specific rank based on both morphological characters, and its ecology and chorology which well allow to distinguish it from Melocactus pachyacanthus ( Table 1; see Taylor 1991: 40–41 and Taylor & Zappi 2004: 381–382).

Chorology: ― Brazil (Central North Bahia).

Illustrations examined: ―Hunt et al. (2003: 174 fig. 174.5), Taylor (1991: 42 pl. 16 fig. below left type coll.), Taylor & Zappi (2004: 403 pl. 60 fig. 60.2 type coll.), Taylor & Zappi (2020: 257 fig. 1. A).

Relevant literature: ― Guiggi (2020a –b), Taylor (1991), Taylor & Zappi (2004, 2020).

Figures

FIGURE 1. Isotype of Melocactus pachyacanthus subsp. viridis (≡ Melocactus neoviridescens) (K000013184!). Photo © copyright of the Board of Trustees of the Royal Botanic Gardens, Kew.