Pyrostria Comm. ex Juss.

Lantz, Henrik, Klackenberg, Jens, Razafimandimbison, Sylvain & Mouly, Arnaud, 2007, Three new species of Vanguerieae (Rubiaceae) from Madagascar, Adansonia (3) 29 (1), pp. 129-136 : 133-134

Genus Pyrostria Comm. ex Juss.

Pyrostria pendula

Lantz, Klack. & Razafim., sp. nov. ( Fig. 2 )

Species haec a congeneribus ceteris floribus pendulis et pedicellis persistentibus differt. Apices bracteae longe subulati.

TYPUS. — Madagascar. Antsiranana Province, Andapa District, Marojejy Massif , 3.II.2006, fl., Razafimandimbison & Ravelonarivo 626 (holo-, S; iso-, MO, TAN).

DESCRIPTION

Much branched shrub, 2-3 m tall. Branches slender, terete, glabrous, with a few lenticels. Leaves opposite, present on recent growth and to a smaller extent on older branches but soon caducous, glabrous; petiole 3-6 mm long; blade elliptic to (rarely) obovate, 16-28 × 8-16 mm, cuneate at base and decurrent, acute to slightly acuminate at apex, coriaceous, with revolute margins when dry; venation pinnate, arched; mid-rib prominent, slightly raised on lower surface, raised at basal part on upper surface when dry but disappearing towards apex; lateral nerves not visible when dry or with 1 or 2 faintly visible pairs; tertiary nerves not visible;domatia present as hair-filled pits in axils of main nerves; young stipules ± subulate, older ones with broadly ovate basal part with thin margins and brown hairs within, 2 × 2 mm, and with thicker central part, abruptly and subulately protruding long above basal part. Female inflorescences axillary on 2-3 mm long peduncles, 1-3-flowered; peduncular bracts large, 4-5 mm long, long acuminate, glabrous, enclosing the young inflorescence; pedicels pendulous, 5-6 mm long at anthesis, up to 12 mm long in fruit, persistent in dry state even after fruit dehiscence. Female flowers: calyx glabrous; tube 1- 1.5 mm long; limb tube 0.3 mm long; lobes very broadly triangular, 0.3 × 0.8 mm. Corolla 4-5-merous, white, glabrous outside; tube bell-shaped, 2 mm long, at mouth filled with moniliform and verrucose hairs; lobes rounded triangular, 2 × 2 mm, recurved, acute to slightly acuminate at apex and thickened into a very short apiculum. Stamens attached to corolla tube near mouth; anthers subrotund, 0.5 mm long, included to partly exserted. Style including stigmatic head 3-3.5 mm long, shortly exserted; stigmatic head 1 mm long, deeply bilobed, style not recessed into the stigmatic head; disk glabrous. Ovary 2-locular. Male flower unknown.Fruits glabrous, slightly wider than long, 7 × 8 mm, not or very slightly indented at apex, truncate at base; pyrenes 2.

HABITAT

Wet and cloudy evergreen forests at c. 1900 m altitude.

REMARKS

Pyrostria pendula is only known from the type collection. This species was collected at the same locality as the type of Peponidium crassifolium in the Marojejy Massif. P.pendula is easily recognized by its pendulous flowers and persistent pedicels. This combination of characters is unique in the tribe and the species is unlikely to be confused with other species. The only known specimen is female, evidenced by the absence of pollen and the presence of fruits, but atypically the flowers are sometimes 4-merous, a character usually attributed to male individuals of dioecious Vanguerieae . The presence of long acuminate bracts enclosing the young inflorescence clearly suggests a position in Pyrostria , which is also supported by molecular data (Razafimandimbison et al. unpubl. data).

Figures

FIG. 2. — Pyrostria pendula Lantz,Klack.& Razafim.: A, flowering branch;B, close-up of female inflorescences;C, flower bud;D, female flower, one corolla lobe and corresponding part of tube removed, tangential longisection; E, part of female corolla; F, close-up of hair from inside of corolla; G, style; H, fruit. Scale bars: A, 1 cm; B, H, 5 mm; C-E, G, 3 mm; F, 0.5 mm.