Phylogenetic relationships of Caralluma R. Br. (Apocynaceae)

Abstract

In this paper we investigate phylogenetic relationships for Caralluma R. Br. (Apocynaceae‐Asclepiadoideae‐Ceropegieae), the largest genus among the stapeliads, using analyses of data from four molecular markers: two plastid regions psbA‐trnH and trnT‐F and two nuclear regions ITS and ncpGS. Our analyses show that the stapeliads consist of two lineages, with Caralluma dominating one of these lineages. Within this lineage, Caralluma is not monophyletic, with its species distributed among two major clades. One of these clades contains species of Caralluma and representatives of Anomalluma Plowes, Echidnopsis Hook. f. and Rhytidocaulon P.R.O. Bally, while in the other clade the small genera Edithcolea N.E. Br., Frerea Dalz. and Pseudolithos P.R.O. Bally are embedded among species of Caralluma. We discuss morphological features that characterize some of the clades. Caralluma is mainly paleotropical in its distribution and is the most widely distributed group among the stapeliads, from the Canary Islands in Macaronesia to the Indian subcontinent. We show that the Indian subcontinent has been invaded four times by species of Caralluma, while its greatest diversity is found in North‐East Africa and southern Arabia.

Recent radiation of Brachystelma and Ceropegia (Apocynaceae) across the Old World against a background of climatic change

“…Our results suggest that, early in the history of Brachystelma/Ceropegia in SE Asia, one group (here represented by C. longifolia and C. pubescens) spread into the Himalaya and further east and another spread into and diversified in Peninsular India. This is different from Caralluma (Bruyns et al, 2010), where one predominantly temperate group reached the Himalaya of India and Nepal via the Arabian Peninsula, Persia and Pakistan, while a different lineage gave rise to the species in southern India.…”

“…Many new cases of disjunctions within clades were recorded for the first time in Caralluma (Bruyns et al, 2010) and Euphorbia L. subg. Euphorbia (Bruyns et al, 2011;Dorsey et al, 2013), where most of the Indian succulent species arose within the African species and then spread further into SE Asia.…”

“…To these can be added the three separate invasions of SE Asia identified in Caralluma R. Br. (Bruyns et al, 2010) to give six dispersal events from Africa to SE Asia in the ingroup.…”

“…Ceropegiella). The most diverse group of succulents in the Apocynaceae is the ±350 species of the stapeliads, which are all very fleshy stem-succulents (Bruyns, 2000;Bruyns et al, 2010Bruyns et al, , 2014.…”

Caralluma bicolor sp. nov. (Apocynaceae, Asclepiadoideae) from India

“…belongs to the subfamily Asclepiadoideae of the Apocynaceae. Caralluma is mainly paleotropical in its distribution and is the most widely distributed group among the stapeliads, from the Canary Islands in Macaronesia to the Indian subcontinent (Bruyns et al 2010). Gandhi (1999) brought to light the inadequacy of information and the need for a critical revision of the Indian species.…”