Hilsenbergia comorensis 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 : 167-168

5. Hilsenbergia comorensis J.S. Mill. , sp. nov.

Arbor usque ad 12 m alta, ramunculis glabris. Folia decidua, alterna; lamina lanceolata usque ovata , 6.5- 16 cm longa, 3.3-6 cm lata, apice acuminata , basi rutundata usque obtusa , margine integra et minute revoluta , utrinque glabra vel adaxialiter puberula secus nervos principales; petiolo 15-30(-40) mm longo. Inflorescentiae cymosae, usque ad 7 cm latae. Flores non visi. Fructus drupaceus, depresse-globosus, 4-5 mm longus, 5-8 mm in diam.; pyrenis 4, alatis.

TYPUS. — Pascal 504, Comores, Mayotte, Hachiroungou, 450 m, fr., 16 Apr. 1996 (holo-, P!; iso-, K!).

Tree to 12 m tall, the twigs glabrous; leaves deciduous, alternate, borne only on the current season’s growth, deciduous; blades lanceolate to ovate, the wides point below the middle, 6.5-16 cm long, 3.3- 6 cm wide, the apex acuminate, the base rounded to obtuse, the margin entire and minutely revolute, the adaxial surface glabrous or with short hairs along the major veins, the abaxial surface glabrous, the venation brochidodromous, the midrib impressed on the adaxial surface, raised on the abaxial surface, the secondary veins 8-12, the tertiary venation reticulate; petioles 15-30(-40) mm long, glabrous, narrowly canaliculate on the adaxial surface.

Inflorescences terminal, cymose, to 7 cm broad, the branches glabrous. Flowers unknown.

Fruits drupaceous, borne in the persistent, c. 5 mm wide calyx, orange at maturity, depressed globose, 4-5 mm long, 5-8 mm broad, the endocarp bony, separating into 4 single-seeded pyrenes at maturity, 4 mm long, 2.3 mm wide, the dorsal surface with parallel, papery wings. — Fig. 7 .

Hilsenbergia comorensis is a distinctive species, perhaps most easily confused with H. petiolaris , from which it differs most conspicuously in having leaves that are widest below the middle, rounded to obtuse at the base, and acuminate at the apex. The leaves of H. petiolaris , in contrast, are to widest at the middle, acute to obtuse at the base, and obtuse to acuminate at the apex.

DISTRIBUTION. — Hilsenbergia comorensis is known from only two collections, both from the island of Mayotte in the Comores ( Fig. 6 ).

VERNACULAR NAME. — Chipapou Lahi.

CONSERVATION STATUS. — Provisional IUCN Red List Category: Critically Endangered (CR B1ab(I-iv) + 2ab(I-iv)). Hilsenbergia comorensis has been collected only twice on the island of Mayotte. Available habitat is both limited and threatened.

PARATYPE. — COMORES: Pascal 890, Mayotte ,

Convalescence, 400 m, fr., 19 Feb. 1997 ( P!) .

Figures

Fig. 7. — Hilsenbergia comorensis J.S. Mill.: A, fruiting branch; B, whole fruit with persistent calyx; C, dorsal surface of pyrene. Pascal 504. Drawn by A. JOUY.

Fig. 6. — Distributions of Hilsenbergia species, mapped on the simplified bioclimate zones of Madagascar (after CORNET 1974; see SCHATZ 2000).