Disocactus, Lindley, 1845

Korotkova, Nadja, Borsch, Thomas & Arias, Salvador, 2017, A phylogenetic framework for the Hylocereeae (Cactaceae) and implications for the circumscription of the genera, Phytotaxa 327 (1), pp. 1-46 : 12

The Disocactus clade

The clade that includes the nomenclatural type D. biformis (Lindley) Lindley is supported with 1 PP, 78% MLBS, 86 % JK. This confirms the results of Cruz et al. (2016), who recovered a Disocactus clade with the same composition with higher support from 96% BS and 96% JK, and 1 PP from Bayesian Inference (ML not calculated therein). Resolution and node support within Disocactus are generally low.

Disocactus was originally described by Lindley (1845) for D. biformis and was characterized by dimorphic stems and small flowers. The widely-used concept of Disocactus was established by Barthlott (1991), who amplified the genus by including the genera Aporocactus , Nopalxochia Britton & Rose , and Heliocereus (A. Berger) Britton & Rose, all with diurnal, large, bright red or pink flowers, to Disocactus . In this sense, Disocactus is polyphyletic, since Aporocactus is resolved outside and three Epiphyllum species (see above) are resolved within Disocactus with high confidence. This is also consistent with the results obtained by Cruz et al. (2016), who also already published the necessary new combinations for these Epiphyllum species under Disocactus . Disocactus crenatus (Lindley) M.Á. Cruz & S. Arias (2016: 157) has diurnal flowers, what had always appeared as unusual within the exclusively night-flowering Epiphyllum . Flowers of D. crenatus and D. anguliger (Lemaire) M.A. Cruz & S. Arias (2016: 157) have in fact stamens inserted in two series, a character that is common in Disocactus such as the flowers that open in the evening and last for several days. Furthermore, both species can hybridize with other species of Disocactus , but not of Epiphyllum ( Bauer 2009) .