Lindernia adami-hefiedi Eb.Fisch. sp. nov. (Figs. 1–5).

Type:— MADAGASCAR. Antsiranana. Montagnes d’Ambre National Park, près de sommêt d’Ambre, autour du Grand Lac (=Matsabory Malio), 12°38’S 49°09’E, 1400–1475 m, 9–13 April 1993, O.Andrianantoanina, S.Malcomber, A. Solotiana & Rabety 57 (holotype P03997589!, isotype TAN!, MO!).

Diagnosis: — Lindernia adami-hefiedi differs from Lindernia rotundifolia and all related species (Lindernia lemuriana, L: oblongifolia, L. viguieri) in the dense long-stalked glandular hairs on stems, leaves, pedicels and calyx. The leaves are matt in L. adami-hefiedi and conspicuously shining in the other four species. The pedicels are 12–20 mm long in L. adami-hefiedi and 5 mm long in L. rotundifolia, 20–30 mm long in L. oblongifolia, 5 mm in L. lemuriana and 3–4 mm in L. viguieri. The filiform staminodes lack a filiform appendage and are 3–3.5 mm long in the free part, while they are not exceeding 2.5 mm in the other species. For an overview of the diagnostic characters see Tab. 1.

Description: —Prostrate or ascending perennial herbs. Stems, leaves and pedicels densely covered with long-stalked glandular hairs, 0.3–0.5 mm long. Stems up to 35 cm long, rooting at the nodes, slightly quadrangular, that is c. 1 mm in diameter. Leaves opposite, well spaced by internodes of 15–18 mm, rounded-orbicular, with three main veins, surface matt, 6–8 × 8–10 mm, apex obtuse. Inflorescences frondose, with leaf-like bracts, flowers axillary and solitary, each node of bracts with just one fertile bract bearing a flower; flowers ebracteolate; pedicels 12–20 mm long. Calyx dull green with lobes extending to near the base, tube 0-5– 1 mm long, 5-lobed with obtuse lobes 3–4 mm long, densely covered with long-stalked glandular hairs. Corolla white with deep blue marks, bilabiate; tube held erect, cylindrical, 6.5–7 mm long, c. 3–4 mm in diameter; upper lip hooded, 4–5 mm long, triangular-attenuate from broad base, 4–5 mm wide at base, narrowed near apex, distinctly emarginated; lower lip with three rounded obtuse lobes 4.5–6 mm long and 4–4.5 mm wide, palate minutely puberulous with minute clavate hairs up to 0.1 mm long, centrally and extending into throat. Stamens two, adaxial, attached at base of upper lip, filaments 1.8–2 mm long, glabrous, convergent, the divergent anther thecae forming a cross-shape, thecae 1.5 mm long, obtuse at apex; abaxial staminode s attached in tube, lower part connate with tube, 3–3.5 mm long, densely covered with yellow glands, free part clavate, slightly curved at apex or straight, 3–3.5 mm long and 0.3–0.5 mm wide, densely covered with blue glands. Pistil glabrous; ovary oblong, 2–2.5 mm long; style slender, 4–5 mm long; stigma of two broad membranous lobes, ± 0.8–1 mm in diameter. Mature fruit up to 3.5 mm long. Seeds not alveolated, with shallow longitudinal ribs.

Additional specimens seen (Paratypes):— MADAGASCAR. Montagne d’Ambre, Lac Maudin, 12°34’S 49°09’E, 1100–1250 m, 03.–10.June 1993, O. Andrianantoanina & R.Bezana 163 (P03997590, MO); Montagne d’Ambre, bords du Grand Lac, 7. October 2014, E.Fischer 133 (TAN, KOBL); Montagne d’Ambre, bords du Grand Lac, June 1970 Bosser 20366 (P03416732); Ouest: bords des étangs, des ruisseaux montagne d’Ambre, vers 600 m. alt., sur le basalte, November 1909, H.Perrier de la Bâthie 8500 (P00057101).

Distribution:— Madagascar, Montagne d’Ambre National Park, only known from the type locality.

Habitat:—Volcanic rocks at shores of volcanic lakes in montane rainforest, 1100–1475 m, occasionally below at 600 m.

Etymology:—Named after Adam Zakaria Hefied, borne in Algiers on 22 March 2023.

Conservation status.— Lindernia adami-hefiedi has at present only been observed at the type locality. Here, it was found on volcanic rocks at the shore of the Grand Lac and two other lakes in Montagne d’Ambre National Park, and there is no observation of an actual threat at this locality. Moreover, the location is situated in a protected area. Thus the species is provisionally assessed as LC (Least Concern).