Vitex madiensis subsp. milanjiensis (Britten) F.White

Meerts, Pierre, 2018, Synopsis of the genus Vitex (Lamiaceae) in the Democratic Republic of the Congo, Plant Ecology and Evolution 151 (3), pp. 380-392 : 387-388

11b. Vitex madiensis subsp. milanjiensis (Britten) F.White

( White 1962: 455); Verdcourt (1992: 61); Lebrun & Stork (1997: 524); Sales (2001: 197; 2005: 84); Coates Palgrave & Coates Palgrave (2005: 983); Meerts & Hasson (2016: 336); Meerts (2016: 231).

– Vitex madiensis var. milanjiensis (Britten) W.Piep. ( Pieper 1928: 63) ; De Wildeman (1929a: 12; 1929b: 105); Delevoy (1929: 483).

– Vitex milanjiensis Britten ( Britten 1894: 36) ; Baker (1900: 330).

– Types: Malawi, Milanji [Mulanje], 6000 ft [1800 m], Oct. 1891, Whyte 138 (syn-: BM barcode BM001124551); Malawi, Zomba, Sept. 1891, Whyte s.n. (syn-: BM barcode BM000566972; Kbarcode K000249031 ).

Vitex grisea Baker ( Baker 1900: 325) .

– Type: Angola, Distr. Huilla, in silvestribus alte dumetosis de Catumba, Welwitsch 5759 (lecto-: Kbarcode K 001067050, designated here ; isolecto-: BM barcode BM 000839718), synon. nov .

Vitex huillensis Hiern ( Hiern 1900: 837) ; De Wildeman (1914b: 191) nom. illeg.

Vitex hockii De Wild. ( De Wildeman 1914b: 113; 1914c: 403; 1921: 164); Pieper (1928: 61); Delevoy (1929: 483).

– Type: D.R. Congo, Haut-Katanga, Manika , Oct. 1911, Hock s.n. (holo-: BR barcode BR 0000008906557) .

Vitex ringoetii De Wild. ( De Wildeman 1914a: 143; 1914c: 407; 1921: 165).

– Type: D.R. Congo, Nieuwdorp, Oct. 1912, Ringoet 1 (holo-: BR barcode BR 0000005571505) .

Vitex epidictyodes Mildbr. ex W.Piep. ( Pieper 1928: 61; 1929: 164).

– Vitex madiensis subsp. milanjiensis var. epidictyodes (W.Piep.) Verdc. ( Verdcourt 1992: 61) ; Lebrun & Stork (1997: 525).

– Type: Malawi, Langenburg, am nordende des Nyassa , Stolz 556 (First-step lectotype designated by Pieper (1929); second-step lectotype: Bbarcode B 100279988, designated here ; isolecto-: BM barcode BM001125198, Gbarcode G00366697, Pbarcode P00713461, Ubarcode U0040942, Zbarcode Z-000067396) .

Differs from the type subspecies by the following traits. A shrub. Twigs stout, often wine red. Leaves 5 foliolate; lamina abruptly contracted at tip and cuspidate, very coriaceous, entire; upper surface very scabrid, reticulum prominulent.

Distribution – Zambezian region, from Angola eastwards to Tanzania and Mozambique.

Notes – Dwarf, geofrutescent forms of V. madiensis subsp. milanjiensis occur throughout the distribution range of subsp. milanjiensis . They have been repeatedly described as V. hockii De Wild. , V. ringoetii De Wild. , V. epidictyodes W.Piep. , V. caespitosa Exell. Such forms pose two different taxonomic problems. First, it is unclear if they are genetically fixed or if, alternatively, they represent pyrophytic forms induced by burning; Verdcourt (1992) favoured the former hypothesis. Secondly, assuming it is genetically fixed, it is not clear if that morph is monophyletic or, alternatively, if it has evolved several times independently in response to selection by fire or other environmental constraints. Ihave not been able to find differences between dwarf and tall morphs except size.

Lectotypification of Vitex epidictyodes Mildbr. ex W.Piep. Three syntypes are cited in the protologue (Stolz 556; Stolz 1478; Trotha 95). Pieper (1929) designated Stolz 556 as the lectotype (see Verdcourt 1992). Many specimens of that gathering have been distributed and Pieper (1929) did not indicate a specific herbarium; therefore second-step lectotypification is necessary (art 9.17 of ICN; McNeill et al. 2012). Since Pieper worked in Berlin, Itherefore select the specimen kept in Berlin as the lectotype.

Lectotypification of Vitex grisea Baker. The specimen of Welwitsch 5759 deposited in Kis chosen as the lectotype for two reasons. First it shows better the acute leaflet tips mentioned in the protologue; secondly, Baker worked at Kew Botanic Gardens after Welwitsch’s collections were split and, therefore, almost certainly used the duplicates deposited in K. This morphotype is a somewhat extreme variant in the phenetic variation space of the polymorphic Vitex madiensis subsp. milanjiensis not deserving formal taxonomic recognition.