Vitex congolensis var. congolensis

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 : 381-384

4a. Vitex congolensis var. congolensis

Vitex aesculifolia Baker ( Baker 1900: 325) ; Durand & Durand (1909: 436).

– Type: D.R. Congo, Monbuttu, near Munsa , 7 Apr. 1870, Schweinfurth 3442 (holo-: K) .

Vitex seretii De Wild. ( De Wildeman 1909: 130); Pieper (1928: 59); Lebrun & Stork (1997: 526).

– Type: D.R. Congo, Nala, Mar. 1907, Seret 847 (lecto-: BR barcode BR0000008906229 designated here; isolecto-: BR0000008906212), synon. nov.

Vitex thonneri De Wild. ( De Wildeman 1911: 246); De Wildeman (1912a: 467; 1912b: 216, 262; 1929a: 16); Pieper (1928: 59); Lebrun & Stork (1997: 526).

– Type: D.R. Congo, Ubangui, Banzyville [Mobayi-Mbongo], à 450 m d’altitude dans les broussailles, parmi les rochers, 8 Mar. 1909, Thonner 263 (lecto-: BR barcode BR0000008906540 , designated here; isolecto-: BR barcodes BR0000008906243 & BR0000008906250, Wbarcode W 1911-0005189, Kbarcodes K000192755 & K000192756), synon. nov.

Vitex gilletii Gürke ( Gürke 1903: 298) ; De Wildeman (1903b: 72; 1912a: 467; 1912b: 91, 242); Durand & Durand (1909: 437); Lebrun & Stork (1997: 524).

– Vitex congolensis De Wild. & T.Durand var. gilletii (Gürke) W.Piep. ( Pieper 1928: 59) .

– Type: D.R. Congo, Kimuenza, May 1901, Gillet 2163 (lecto-: BR barcode BR0000008903662, designated here).

A tree. Young twigs, petiole and inflorescence with long spreading ferrugineous or fulvous fine hairs. Leaflets 5; petiolule 0–5 mm; lamina softly fulvous pubescent beneath. Inflorescence a dichasium on a long peduncle; calyx 1.5–2.5 mm, ferrugineous to fulvous pubescent; ovary glabrous; corolla 5–7 mm, cream with bluish lower lip. Fruit 10–15 mm long.

Distribution – Wand C Africa, from Ivory Coast southwards to Angola and eastwards to Sudan.

Notes – Lectotypification of Vitex congolensis De Wild. The protologue cited only one collection (Dewèvre s.n.). The material stored at BR comprise Dewèvre 770a (2 sheets) and Dewèvre 926a (3 sheets); one sheet has locality description and notes handwritten by De Wildeman (BR0000008905918); it is here chosen as the lectotype. Remaining syntypes: sine loco, sine dato, Dewèvre 926a (BR barcodes BR0000008905406 & BR0000008905413).

Lectotypification of Vitex thonneri De Wild. The protologue cited Thonner 263, which has been widely distributed to several herbaria. Of the three sheets in BR, the one with De Wildeman’s handwriting on the label is selected as the lectotype. The original material has the diagnostic characters of V. congolensis ; it is unusual in having short leaflets, but this trait is variable within the species and Ido not think this variant is worth taxonomic recognition.

Lectotypification of Vitex gilletii De Wild. Only one of the two syntypes has been found (Gillet 2163); the other syntype (Pogge 698) has probably been destroyed in Berlin and no duplicate could be traced. The type material of V. gilletii has leaflets with a somewhat unusual shape (low length/width ratio), abruptly contracted in a relatively long acumen. However, V. congolensis has a variable leaflet shape and size and it is impossible to discriminate taxa on that basis.