Systematics Of Psilocaulon N. E. Br. (Aizoaceae)

ABSTRACT

On the basisl of herbarium, living and pickled material

the morphology and systematics of Psilocaulon N. E. Brown

sensu Ihlenfeldt ~ Bittrich is investigated. Thirteen species

{including one insufficiently known species) are recognized:

' P. articulatum, PI· bicorne, P. coriarium, P. dimorphum, P.

dinteri, P. foliosum, P. gessertianum, P. granulicaule, P.

junceum, P. leptafthron, P. parviflorum, P. sal.icornioides, P.

subnodosum. Species of Mesembryanthemum, Prenia, Brownanthus,

Aspazom~ and Apte~ia are used as outgroups in a cladistic

analysis of Psilobaulon. The monophyly of Psilocaulon is

demonstrated. Asia result P. rapaceum Jacq. is excluded and

transferred to caulipsolon Klak gen. nov. The position of

Psilocaulon and t~e monotyp1.'c genus Caulipsolon within the

subfamily Mesembryanthemoideae is discussed. However,

relationships of fsilocaulon and Caulipsolon to other genera

remain obscure, s~nce no synapomorphies were found to indicate

sister relationships. More sampling among outgroups and/or a

future molecular ~tudy may help to elucidate relationships

among the genera of the Mesembryanthemoideae. Geographical

distribution pattfrns for all species and the number of

species per half-degree grid square are given. It is

discussed how speties diversity and geographical distribution

in Psilocaulon coAtrasts with or corroborates existing ideas

of centres of divjrsity and distribution patterns in the

Mesembryanthema. Each species is described in detail. A

description of thi. genera Psilocaulon and Caulipsolon is given

and a key to the pecies is provided. Material examined is

cited and full syjonomy is given.

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