Hilsenbergia labatii J.S. Mill., 2003

Miller, James S., 2003, Classification of Boraginaceae subfam. Ehretioideae: Resurrection of the genus Hilsenbergia Tausch ex Meisn., Adansonia (3) 25 (2), pp. 151-189 : 173-174

8. Hilsenbergia labatii J.S. Mill. , sp. nov.

Arbor usque ad 10(-20) m alta, cortice subtiliter fissurata, ramunculis glabris. Folia decidua, alterna; lamina late-ovata usque orbiculata, 5-10.5 cm longa, 3-7(-8) cm lata, apice obtusa usque rotendata, plumerque abrupte acuminata , basi obtusa usque acuta vel cuneata , margine integra, utrinque glabra ; petiolo 1.7-4.3 cm longo. Inflorescentiae terminale, paniculata , anguste-pyramidalis, 6-10.5 cm longae. Flores bisexuales; calyce campanulato, 4-5 mm longo, 4-5-lobo, extus glabro; corolla alba vel pallide chloroleuca, tubulari, 5 lobis reflexis. Fructus drupaceus, globosus, 3-4 mm longus, 3-5 mm in diam.; pyrenis 4, alatis.

TYPUS. — Humbert 18924, Madagascar, Prov. Antsiranana, collines et plateaux calcaires de l’Ankarana, 300 m, 12°54’S, 49°08’E, fl., Dec. 1937 - Jan. 1938 (holo-, P!; iso-, G!, K!, MO!, P!, TEF!, WAG!) .

Tree to 10(-20) m tall, to 60 cm dbh, the bark finely fissured, the stems glabrous. Leaves deciduous, borne only on the current season’s growth, alternate; blades widely ovate to orbicular, 5-10.5 cm long, 3-7(-8) cm wide, the apex obtuse to rounded and usually abruptly acuminate, the acumen usually somewhat reflexed, the margin entire, both surfaces glabrous, the venation brochidodromous, the midrib impressed near the leaf base, the secondary veins (4-)5-6(-8), the tertiary venation reticulate; petioles 1.7-4.3 cm long, narrowly canaliculate on the adaxial surface, glabrous.

Inflorescences terminal, a narrowly pyramidal panicle 6-10.5 cm long, 4-6.5 cm broad near the base, the peduncle 2.5-4 cm long, peduncle and branches glabrous. Flowers bisexual; calyx campanulate, persistent in fruit, 4-5 mm long, the lobes valvate, 4-5, sometimes tardily separating and appearing only 3 in flower, triangular to widely triangular, 1-2 mm long, 1.5-2 mm wide, glabrous; corolla white to pale greenish white, tubular with reflexed lobes, 5-lobed, the lobes widely depressed ovate, 1.5 mm long, 2 mm wide, the tube 3.5-4 mm long; stamens 5, filaments 3 mm long, the upper 1.5 mm free, glabrous, the anthers lanceoloid, c. 1 mm long, the 2 sacs free and slightly divergent at the base; ovary ovoid, 1.5 mm long, 1 mm wide, the style 3 mm long, dichotomously branched at the apex, the 2 stigmas discoid.

Fruit drupaceous, color at maturity unknown, borne in the persistent, spreading calyx, globose, 3-4 mm long, 3-5 mm in diameter, 4-lobed and 4-parted at maturity, the endocarp bony, breaking into 4 single-seeded pyrenes, 3-3.5 mm long, 1.5-2 mm wide, these with thickened parallel ridges on the external surface. — Fig. 10 .

Hilsenbergia labatii is the largest species of the genus, sometimes obtaining a height of 20 m. It is a very distinctive species that can be easily recognized by its paniculate inflorescence. It is named in honor of Jean-Noël LABAT who has contributed significantly to knowledge of the flora of Madagascar and the Comores through his collections and publications .

DISTRIBUTION. — Hilsenbergia labatii is known from only seven collections, all from calcareous substrates in extreme northern and western Madagascar ( Fig. 11 ).

V ERNACULAR NAMES. — Hazomavylahy, Talamosy, Tsarafanahy, Tsarajofy.

CONSERVATION STATUS. — Provisional IUCN Red List Category: Endangered (EN B2ab(i-iv)). The two regions where Hilsenbergia labatii grows are distant, thus it occurs over a wide range in Madagascar, but its distribution is restricted to calcareous substrates and its Extent of Occurrence is only 60 km 2. It does occur in two protected areas, the Réserve Spéciale d’Ankarana and Parc National de Bemaraha.

PARATYPES. — MADAGASCAR: Humbert 18955, Prov. Antsiranana, collines et plateaux calcaires de l’Ankarana, 100-350 m, 12°54’S, 49°08’E, fr., Dec. 1937 - Jan. 1938 (P!); Humbert 19156, Prov. Antsiranana, collines et plateaux calcaires de l’Analamera, 50-400 m, 12°48’S, 49°28’E, fr., Jan. 1938 (P!); Jongkind 3589, Prov. Mahajanga, Tsingy de Bemaraha, RNI, N of Manambolo River, 50 m, 19°09’S, 44°49’E, fr., 18 Dec. 1996 (MO!); Labat & Deroin 2282, Prov. Mahajanga, près du fleuve Ambodiria, à l’est d’Ambinda, RN9, près d’Antsalova, 100-200 m, 18°38’S, 44°42’E, fr., 4 Dec. 1992 (MO!, P!); Service Forestier: SF23146 (Capuron), Prov. Antsiranana, plateau de l’Ankarana, massif d’Ampatsoa, rive droite du Rodo, près de son confluent avec l’Andrafiamena, 12°40’S, 49°34’E, fl., 24 Dec. 1963 (P!, TEF!); Service Forestier: SF24456 (Capuron), Prov. Antsiranana, massif de l’Ambongoabo, à l’ouest de Diégo-Suarez, 12°15’S, 49°10’E, fr., 26 Jan. 1966 (P!, TEF!).

Figures

Fig. 10. — Hilsenbergia labatii J.S. Mill.: A, fruiting branch; B, whole flower; C, open flower showing androecium and gynoecium; D, young fruit with persistent calyx; E, dorsal view of pyrene; F, cross-section of dorsal surface of pyrene. A, D, E, F, Labat 2282; B, C, Humbert 18924. Drawn by A. JOUY.

Fig. 11. — Distributions of Hilsenbergia species, mapped on the simplified bioclimate zones of Madagascar (after CORNET 1974; see SCHATZ 2000).