Ceropegia circinata (E.Mey.) Bruyns

Bruyns, Peter V., Klak, Cornelia & Hanáček, Pavel, 2018, An account of Ceropegia sect. Chamaesiphon (Apocynaceae) in Moçambique with new records and two new species, Phytotaxa 364 (2), pp. 111-135 : 121-122

Ceropegia circinata (E.Mey.) Bruyns ( Figs. 8–10 )

Ceropegia circinata is a widespread species in southern Africa where it has been recorded in Botswana, Namibia, South Africa, Swaziland and Zimbabwe (although absent from Percy-Lancaster (1997), there is a specimen at PRE from Inyangani Mt in Zimbabwe). It is particularly widespread in South Africa, where it has been recorded from the northern provinces to close to Port Elizabeth in the southern part of the Eastern Cape and in some of the drier parts of the Karoo, such as near Beaufort West and Carnarvon. Over this region it is very variable and this is reflected in its extensive synonymy ( Dyer 1980). The six specimens cited below are the first records from Moçambique. They were found over a distance of some 150 km between the towns of Cuamba and Mocuba and at altitudes from below 500 m to over 1200 m ( Fig. 9).

Ceropegia circinata has a wide tolerance of different habitats and may be encountered in flat savanna on ‘Kalahari sands’ (as in Botswana and Namibia: Bruyns 2014) or on stony slopes among low-growing, semi-arid scrub, in mesic shrubland or in grassland ( Bruyns, 1982). Except in Botswana and Namibia, it is mostly found on slopes and flat spots on hills and mountains. In Moçambique it was only found on granitic hills: for example Bruyns 8612 was common in very shallow soil on flat patches on top of an enormous blackish granitic hill with the spiny succulent Euphorbia decliviticola Leach (1973: 13) and E. mlanjeana Leach (1973: 3) ; Bruyns 7698 grew in very shallow soil on granitic domes with lots of Xerophyta and Bruyns 7701 was found in shallow soil on a granitic dome with Aloe , a small species of Crassula Linnaeus (1753: 282) , a small form of Kalanchoe humilis Britten (1871: 397) and Raphionacme splendens Schlechter (1895: 301) .

In Moçambique most plants have pale creamy-yellow flowers with long, slender lobes ( Fig. 8 ) but in Bruyns 9743 the flowers were unusually small and darker brownish inside ( Fig. 10 ). In Bruyns & al. (2015) we included three collections of this species (two from Moçambique including Bruyns 8604 and Bruyns 9743 and one from the Eastern Cape, South Africa). All three proved to be very closely related. The relationships of C. circinata are likely to lie with C. breviflora , C. gemmea and C. gracilior and, although morphologically plausible, this relationship is poorly supported by DNA-data ( Bruyns et al. 2015 and later analyses). In these species the flowers are similarly shaped; the slender corolla-lobes are divided to their bases and usually remain fused apically at anthesis, there is a very short tube (usually <1 mm long) and the outer coronal lobes are deeply divided in their middle into slender pairs of erect lobules.

Figures

FIGURE 8. Ceropegia circinata. A, portion of plant with inflorescence (scale 4 mm); B, side view of flower (scale of A = 4 mm); C, side view of centre of dissected flower (scale 1 mm); D, pollinarium (scale of C = 0.25 mm). Drawn from: Bruyns 8604 (BOL, K, MO).

FIGURE 10. Ceropegia circinata (with smaller flowers).A, plant (scale 10 mm); B, portion of plant with inflorescence (scale 2 mm); C, D, side view of flower (scale 2 mm at D); E, side view of centre of dissected flower (scale 1 mm); F, pollinarium (scale 0.25 mm). Drawn from:A, B, C, E, Bruyns 9743 (BOL); D, F, Bruyns 7698 (BOL).