Dioscorea buchananii subsp. undatiloba (Baker) Wilkin, 2015

Wilkin, Paul & Muasya, A. Muthama, 2015, Clarifying the Dioscorea buchananii Benth. species complex: a new potentially extinct subspecies for South Africa, PhytoKeys 48, pp. 51-72 : 55

Dioscorea buchananii subsp. undatiloba (Baker) Wilkin comb. & stat. nov. Figure 1

Dioscorea undatiloba Baker, J. Bot. 27: 8 (1889); R.Knuth in H.G.A Engler (ed.), Pflanzenr. 4, 43: 184 (1924).

Dioscorea buchananii subsp. undatiloba Type: South Africa. KwaZulu Natal: Port Natal, Mandini District, Tugela, ♂ fl. & ♀ fl. without date, Gerrard & McKen 1617 (holotype: K post anthesis ♂ fl. & ♀ fl. [K000098906!]; isotype: TCD!, ♀ fl.!)

Dioscorea junodii Burtt-Davy, Kew Bull. 1924: 231 (1924), synon. nov.

Dioscorea buchananii subsp. undatiloba Type: South Africa. Limpopo: Mopani District, Valley of Schambock’s Stadt, near Shilouvane, (Shiluvane) Sanatorium, 24°02'20"S, 30°16'59"E, ♂ fl. Junod 1416 (holotype: K [K00098905!]), non PRE [PRE0093186-0, digital image!]

Type.

Based on Dioscorea undatiloba Baker.

Description.

Leaves consistently moderately to deeply 3, 5 or 7-lobed from stem bases to apices, with irregular, pinnate secondary lobing present on central lobe at least; central lobe to 50 mm long, lanceolate to elliptic or rhomboid, lateral lobes to 33 mm long, oblong to narrowly so, central lobe largest to lobes more or less equal in length and width. Male flowers on 1.7-3.7 mm long pedicels, tepals 2.3-3.7 × 1.0-2.2 mm, torus (1.5-)1.9-3.4 mm in diam.

Distribution.

Endemic to South Africa in Limpopo and KwaZulu Natal provinces. The Limpopo specimens are from localities relatively close to those of the type subspecies in Gaza province of Mozambique.

Vernacular name(s).

Not known.

Ecology.

Ca. 50 to 600 m altitude in KwaZulu Natal, and 700 to 1000 m in Limpopo. Associated geology, soils and vegetation unknown.

Conservation.

Dioscorea buchananii subsp. undatiloba has not been recorded since 1921 in either Limpopo or KwaZulu Natal and is known from only six specimens. However, pending urgently needed searches to find extant populations in Limpopo, KwaZulu Natal and the intervening areas and further research on the relationships between those populations, the most appropriate provisional conservation status assessment is DD. It is conceivable that this taxon is already extinct in part or all of its range, especially extensively developed lowland KwaZulu Natal.

Uses.

None known

Notes.

The specimen labelled Junod 1416 at PRE [PRE0093186-0] is male flowering material of Dioscorea sylvatica Ecklon. This explains the placement of Dioscorea junodii in the synonymy of that species in Govaerts and Wilkin (2015). However, Burtt Davy would have examined and described the K sheet cited above, hence its holotype status and synonymy under Dioscorea buchananii subsp. undatiloba . No specimen of Junod 1416 appears to be preserved at G or Z based on their online databases.

Specimens examined.

South Africa. Limpopo: Mopani District, Shiluvane, 24°02'20"S, 30°16'59"E, ♂ fl. & ♀ fr. May 1905, Junod 2182 (Transvaal Museum 7164), (PRE!); Louis Trichardt, ♂ fl. Jan 1921, Breyer in TM (Transvaal Museum) 23387 (K!, PRE). KwaZulu Natal: uThungulu District, Umvuzaan (uMvuzane) Valley, 28°46'21"S, 31°20'29"E, ♂ fl. buds Jan 1915, Medley Wood 12969 (K!); Pietermaritzburg, Camperdown 29°43'59.91"S, 30°31'59.87"E ♂ fl. Mar 1910, Medley Wood 11673 (K!).