Eulychnia (Phil.)

Walter, Helmut E. & Guerrero, Pablo C., 2022, Towards a unified taxonomic catalogue for the Chilean cacti: assembling molecular systematics and classical taxonomy, Phytotaxa 550 (2), pp. 79-98 : 88

Eulychnia :

—The genus includes two main clades according to Larridon et al. (2018) and Merklinger et al. (2021). The two groups are morphologically and phylogenetically supported and clearly associated with geographical changes in the Atacama Desert (a proposed key is reported below). According to the results of the phylogenetic analyses three former species-complexes were resolved: Eulychnia acida Phil. , E. breviflora Phil. , and E. iquiquensis (K.Schum.) Britton & Rose.

1. Ribs steep and narrow; flowers and fruits densely covered with wool; perianth segments lanceolate (“ breviflora -group”) ............2

- Ribs broad and flattened; flowers and fruits with less and shorter wool; perianth segments spathulate (“ acida -group”) ................6

2. Spines numerous, central ones very long; seed large .................................................................................................. 3. E. breviflora

- Spines less numerous and shorter; seed smaller.................................................................................................................................3

3. Pulp orange; areoles with long wool; plants low to medium-sized....................................................................................................4

- Pulp whitish; areoles with shorter wool; plants higher ......................................................................................................................5

4. Plants shrubby; branches sub-prostrate, thin ........................................................................................................... 2. E. barquitensis

- Plants arborescent; branches ascending, thicker ..................................................................................................... 7. E. saint-pieana

5. Areoles far apart, wool dark brown ........................................................................................................................... 8. E. taltalensis

- Areoles closely set, wool greyish ............................................................................................................................. 6. E. iquiquensis

6. Flower and fruit areoles spiny ....................................................................................................................................... 4. E. castanea

- Flower and fruit areoles spineless ......................................................................................................................................................7

7. Plants shrubby; branches (sub)prostrate with superior portions pointing upwards; ribs 8–12...........................................................8

- Plants arborescent; branches ascending to erect; ribs up to 16 .......................................................................................... 1. E. acida

8. Shrubs low; branches thin, grey-green; flowers with short wool; new areoles with abundant white felt................ 5. E. chorosensis

- Shrubs higher; branches thicker, yellowish-green; flowers with in conspicuous hairs; areoles with short grey felt........................... ............................................................................................................................................................................... 9. E. vallenarensis