Vitex lowryi Callm., Phillipson & G. E. Schatz, 2014

Martin W. Callmander, Peter B. Phillipson & George E. Schatz, 2014, Towards a revision of the genus Vitex L. (Lamiaceae) in Madagascar I: a distinctive new species from Northeastern Madagascar, Candollea 69 (2), pp. 141-147 : 2-4

Vitex lowryi Callm., Phillipson & G. E. Schatz , spec. nova

( Fig. 1 , 2A ).

Typus: MADAGASCAR. Prov. Antsiranana: Tsihomanaomby massif, ca. 23 air-km NW of Sambava, W of Ambavala ( PK 269 on Sambava-Vohémar road , RN 5a), 14°06’08’’S 50°02’46’’E, 150 m, 7.V.2000, Lowry & al. 5178 (holo-: MO-798818 !; iso-: P [ P04396770 ]!, TAN!) .

Haec species a congeneris madagascariensibus foliolis abaxialiter secus venas necnon petiolis petiolulisque indumento ferrugineo-aurantiaco villoso longo persistente copioso vestitis atque indumento longo densissimo pallide aureo inflorescentiam floremque tegente bracteolas brevissimas sicut lobos calycinos occultante distinguitur.

Monocaulous treelet 4-15 m tall. Leaves palmately compound, 3-5-foliolate, with a generally persistent, long, villous, rusty-orange indument; leaflets obovate to elliptic, sub-sessile to shortly petiolulate, chartaceous, the largest (median) leaflets 20-35 X 8-15 cm, the blades undulate, dark green above and olive green below in vivo; base attenuate; apex rounded; margin entire; abaxial surface covered by a dense rusty-orange indument on the veins, with similar but shorter and more sparse indument between the veins; adaxial surface sometimes with sparse and apparently caducous rusty-orange indument on the midrib and main veins, rugose between the veins; midrib and main veins prominent below and somewhat impressed above; petiole stout and stiff, 7-11 cm long. Inflorescence a muchbranched but highly condensed cyme, borne on the trunk and in the axils of leaves, completely covered by a very dense silvery to golden sericeous indument; cyme-branches up to 2-3 cm long, c. 2 mm in diam. Flower c. 3 cm long, sub-sessile, subtended by a very short bracteole obscured by the dense indument. Calyx cupuliform, the lobes reduce to a minute apical tooth, c. 6-8 × 8-10 mm, 5-lobed, sericeous. Corolla zygomorphic, broadly funnel-shaped, c. 25 mm long, 25 mm wide and 30 mm high, 5-lobed; throat c. 5 mm diam. at the base, c. 15 mm diam. at the mouth; inner surface glabrous, pale yellow sometimes lightly tinged dull pink towards the margin; outer surface densely pubescent, pale yellow or dull pink; upper pair of lobes fused, 10 X 10 mm, free for the distal 1/3, the free portions triangular, apices broadly acute; lateral lobes 10 X 6 mm, triangular, apices shortly rounded; lower lobe 10 X 5 mm, lingulate, with a rounded apex. Stamens 4, curved and appressed to the upper lobes; filaments c. 22 mm long, the proximal 7 mm villous, exserted c. 6 mm, pale yellow, the exserted portion sometimes tinged dull pink; anthers compressed ovoid, c. 2 X 1 mm long, purple with pale yellow pollen. Style curved and appressed to the upper lobes, 25-35 mm long, bifid for the distal 3 mm. Fruit unknown.

Observations. – Vitex lowryi falls in a group with four other species in Moldenke’s identification key ( MOLDENKE 1956: 76, couplet 45), characterized by having large 3-7-foliolate palmately compound leaves, with the leaflet length to width ratio of 2-4:1; flowers with tubular (vs. bilabiate) corollas, borne on compact dense, mostly cauliflorous inflorescences. A new identification key to this group of Vitex and other related species will be provided in a forthcoming publication as several other species still need to be recognized. Among these, V. lowryi is easily distinguished in flower from V. hispidissima (= V. congesta ) and V. coursii Moldenke (= V. pulchra Moldenke ) by its short broadly funnel-shaped (vs. long curved cylindric) corolla, and from V. waterlotii Danguy , by the curved stamens and style appressed to the upper lip of the corolla and slightly exserted (vs. the stamens and style straight, patent, and well exserted). It is most similar to Vitex hirsutissima Baker which has a similarly shaped corolla, stamens and style, but it differs by the extremely dense, long, pale golden indument on the inflorescence and outer parts of the flower which obscures the very short bracteoles and calyx lobes (vs. less dense, shorter, red-brown indument, with the longer bracteoles and calyx lobes clearly visible). Vitex lowryi also differs from Vitex hirsutissima by its copious, persistent, long, villous, rustyorange indument on the veins of the abaxial surface of the leaflets, the petioles, and the petiolules (vs. caducous, short, sparse, appressed, red-brown indument on the veins of the abaxial surface of the leaflets, and short, very sparse, appressed, pale grey indument on the petioles, and the petiolules). Vitex masoalensis also belongs to this group of closely related species, but is easily distinguished from V. lowryi (and V. hirsutissima ), with which it shares the short, funnel-shaped corolla and curved stamens and style appressed to the upper lip of the corolla, by its massive, sessile leaves. A set of representative photographs for these six species is given in Figure 2 .

Distribution and ecology. – Vitex lowryi is endemic to north-eastern Madagascar. It is known only from three collections in remnant patches of low elevation (c. 100-300 m) forest between Sambava and Vohemar: on the Tsihomanahomby Massif, Analalava forest near Antsatoby and a forest patch just south of Antsirabe Nord ( Fig. 3 ). The new species is not sympatric with any of the morphological similar species: V. waterlotii is confined to dry forest on limestone in the far north; V. hirsutissima , V. hispidissima and V. masoalensis occur on the Masoala Peninsula and around the Baie d’Antongil area, while V. coursii occurs further south in escarpment forest at mid-elevation near Moramanga and Lac Alaotra.

Etymology. – This plant is named in honor of our friend and colleague Porter P. Lowry II who collected the type specimen. Pete first visited Madagascar in 1986 during the early days of Missouri Botanical Garden’s Madagascar Programme, in which he has played a key role ever since. He has collected more than 2,000 collections in Madagascar and is also responsible for many excellent plant photographs, including several different species of Vitex . His specimens, field description and photographs of the species described here provided us with important information.

Conservation status. – With an EOO of 207 km ², an AOO of 27 km ² and three subpopulations, none situated within the protected area network, Vitex lowryi is assigned a preliminary status of “Endangered” [EN B1ab(i,iii,iv,v)+2ab(i,iii,iv,v)] following IUCN Red List Categories and Criteria ( IUCN, 2012). The new species is known from only three locations in isolated evergreen lowland forest remnants. The available habitat of the species is severely threatened, and is expected to diminish significantly in the future, in which case V. lowryi may become “Critically Endangered”.

Paratypi. – MADAGASCAR. Prov. Antsiranana: env. S Antsirabe-Nord , sur la nouvelle route Vohémar-Sambava , [14°00’11”S 49°57’47”E], 18-21.X.1966, Service Forestier 24890 ( G, MO, P [ P04396771 ], TEF) ; Vohémar, Vohimarina, Fanambana, Antsatoby , forêt de transition d’Analalava , 13°37’32”S 49°59’42”E, 1.VII.2007, Rasoafaranaivo 173 ( MO, P [ P00853158 ], TAN) .

Figures

Fig. 1. – Vitex lowryi Callm., Phillipson & G. E. Schatz. A. Leaf, with detail of indument on abaxial surface inset; B. Inflorescence; C. Flower (front view); D. Flower (three-quarter view). [Lowry & al. 5178, TAN, P, photos] [Drawing: R. L. Andriamiarisoa]

Fig. 2. – Inflorescences of Vitex L. species from Madagascar. A. Vitex lowryi Callm., Phillipson & G. E. Schatz; B. Vitex coursii Moldenke; C. Vitex masoalensis G. E. Schatz; D. Vitex waterlotii Danguy; E. Vitex hirsutissima Baker; F. Vitex hispidissima (Seem.) Callm. & Phillipson. [A: Lowry & al. 5178; B: Antilahimena 8437; C: Schatz 1353; D: Randrianaivo 1099; E: Lowry 4481; F: Lowry 4340] [Photos: A, E-F: P. P. Lowry II; B: P. Antilahimena; C: G. E. Schatz; D: R. Randrianaivo].

Fig. 3. – Map of northern Madagascar showing the distribution of Vitex lowryi Callm., Phillipson & G. E. Schatz (stars), plotted on a map of forest cover in 2000 (grey) following HARPER & al. (2007).