Harrisia tetracantha

Harrisia tetracantha (Labour.) D.R.Hunt (1987)

🌵 Author(s)	David Hunt
🌵 Basionym	Cereus tetracanthus (1855)
🌵 Basionym author(s)	J. Labouret

Etymology

Greek tetra ‘four’ + Greek akantha ‘spine’. Labouret: “Comparing the areoles from the top of the plant to its base, one observes that the number of series of spines has successively increased to four” (“En comparant les aréoles depuis le sommet de la plante jusqu’à sa base, on observe que le nombre des séries d’aiguillons s’est successivement augmenté jusqu’à quatre”). The epithet is also considered a misspelling of tephracantha (Greek tephra ‘ashes’ + Greek akantha ‘spine’), a reference to the “eight brown spines, black at the tip, that over time get covered as with an impalpable ash-grey dust, and persistent in color at the base and tip only” (Labouret).

David Hunt (Bradleya 5: 91-94. 1987):

Rümpler, Schumann, and Weber, followed by Riccobono, Backeberg and others, all treated Labouret’s epithet ‘tetracanthus’ as a typographical error, and ‘corrected’ it to ‘tephracanthus’ (ashy spined), but the case for so doing is debatable. The description certainly calls for eight spines, not four, and the colour notes are distinctive: ‘huit aiguillons bruns, noirs à la pointe, se couvrant avec le temps comme une poussière impalpable griscendré, et persistants dans leur couleur à la base et à la pointe seulement [eight brown spines, black at the tip, that over time get covered as with an impalpable ash-grey dust, and persistent in color at the base and tip only].’ So far so good; but then the small print (l.c. page 26; always read the small print!) says: ‘En comparant les aréoles depuis le sommet de la plante jusqu’à sa base, on observe que le nombre des séries d’aiguillons s’est successivement augmenté jusqu’à quatre’. The epithet ‘tetracanthus’ evidently did not mean four-spined, but might have been intended, perhaps, to mean ‘with the spines in 4 series’.

If, on the contrary, ‘tetracanthus’ was a typographical error, Labouret (who contributed another article in the same volume) did not bother to correct it later (the index to the volume has ‘tepracanthus’, which solves nothing!). And there is a further objection to ‘tephracanthus’: it would be a homonym of Cereus tephracanthus, attributed to Link & Otto by Steudel, which, under the Rules (cf. Art. 32.4), could be considered to be a validly published new combination by Steudel, based on Echinocactus tephracanthus Link & Otto (despite the fact that Steudel also listed E. tephracanthus Link & Otto as an alternative accepted name).

In the circumstances, and in whatever genus the species is classified, it seems the proper course to re-adopt the original epithet.

Urs Eggli and Reto Nyffeler (Repert. Pl. Succ. LXIV (2013): 13. 2014):

[The epithet] is given as ‘tetracanthus’ in Rev. Hort., but as ‘tephracanthus’ in Neue Blumen-Zeitung. Since the ash-grey colour and texture of the spines is specifically mentioned both in the French description as well as in the Latin diagnosis in Neue Blumen-Zeitung, the correct spelling is taken to be ‘tephracanthus’.