Peponidium Arènes, 1960

Lantz, Henrik, Klackenberg, Jens, Razafimandimbison, Sylvain & Mouly, Arnaud, 2007, Three new species of Vanguerieae (Rubiaceae) from Madagascar, Adansonia (3) 29 (1), pp. 129-136 : 131-132

Genus Peponidium Arènes

Peponidium crassifolium

Lantz, Klack. & Razafim., sp. nov. ( Fig. 1 )

Species haec a congeneribus ceteris foliis succulentis differt; ramis validis, foliis obovatis et crassis cum nervis obscure visibilibus etiam dignoscenda.

TYPUS. — Madagascar. Antsiranana Province, Andapa District, Marojejy Massif , 3.II.2006, fl., Razafimandimbison & Ravelonarivo 628 (holo-, S; iso-, MO, TAN).

PARATYPES. — Madagascar. Antsiranana Province, Ambanja District, Réserve spéciale de Manongarivo: Bekolosy, cours supérieur de la Bekolosy, crête rive gauche, entre CR11 et CR12 , 14°02’S, 48°18’E, 1240 m, 28.III.1996, fr., Gautier & Be 2913 ( G, P). — Andranomalaza, source, 200 m au N du point coté 1728, 14°02’S, 48°25’E, 1720 m, 26. V .2000, fr., Gautier & Rakotomamonjy 3677 ( G, P). — Antsatrotro, à l’Est d’Ankaramibe , 14°05’S, 48°24’E, 679-1876 m, 15. I .1994, fl., Rakotomalala & Narison 187 ( MO, P). — Crête bordant la cuvette d’Antsahakolona, 14°03.266’S, 48°24.488’E, 1731 m, 25.XI.2000, fr., Wohlauser et al. 389 ( G, P). — Andapa District, Réserve naturelle intégrale de Marojejy, 10.5 km NW of Manantenina, along tributary at head of Andranomifototra River , Campement 4, 14°26’24”S, 49°44’30”E, 1625 m, 4-13.XI.1996, fl., fr., Rakotomalaza et al. 892 ( MO, P) .

DESCRIPTION

Shrub, 1.5-4 m tall, rarely tree. Branches stout, compressed when young becoming terete, with thick nodes giving older branches a knobbly appearance, glabrous. Leaves opposite, persistent up to six nodes, glabrous; petiole 5-12 mm long; blade obovate, 30-70 × 15-40 mm, cuneate at base and decurrent, blunt at apex, thick and slightly succulent; venation pinnate, arched, best visible on upper surface; mid-rib distinct, ± even with leaf surface on lower side, distinctly raised on upper surface when dry; lateral nerves not visible or with 3 or 4 faintly visible pairs; tertiary nerves not visible; domatia absent; stipules broadly obovate to triangular, 6 × 5 mm, blunt at apex, glabrous on both sides, early caducous. Inflorescences axillary, sessile, fasciculate, 5-10-flowered; peduncular bracts fused to form a cupular structure; pedicels 2-3 mm long. Male flowers: calyx: tube 1-1.5 mm long; limb tube 0.5 mm long, truncate to minutely toothed; lobes absent or in form of ciliately haired shallow teeth. Corolla 5-merous, white to yellowish, glabrous outside, at mouth densely provided with usually retrorse verrucose hairs; tube ± cylindric, 2 mm long; lobes triangular, 3-4 × 1.6-1.9 mm, acute and thickened at apex; apex bent inwards. Stamens attached to corolla tube near mouth; anthers oblong, partly exserted. Style including stigmatic head 4 mm long, shortly exserted; stigmatic head 1.1 mm long, vaguely ridged, apically bilobed; style slightly recessed into the stigmatic head; disk reduced, ovary absent. Female flowers: calyx: tube 2-3 mm long; limb tube 0.5 mm long, truncate to minutely toothed, often ciliate at margin; lobes absent or in form of ciliately haired shallow teeth. Corolla 5-6-merous, white, glabrous outside, at mouth densely provided with usually retrorse verrucose hairs; tube ± cylindric, 1-2 mm long; lobes triangular, 2-3 × 1.3-1.8 mm, acute and thickened at apex; apex bent inwards. Stamens attached to corolla tube near mouth; anthers oblong, partly exserted. Style including stigmatic head 4 mm long, shortly exserted; stigmatic head 1 mm long, vaguely ridged, deeply bilobed; style slightly recessed into the stigmatic head; disk glabrous. Fruit green-brownish turning orange-reddish, slightly bilobed, 7-11 mm long, 7-11 mm wide, cuneate at base, somewhat laterally compressed, flesh deep, pedicel 3-4 mm long. Pyrene straight, slightly flattened abaxially, 6-9 × 3-4 mm, cartilaginous (very thin and smooth), with an apical prominent line of dehiscence. Seed albuminate, entire, a straight embryo with very short cotyledons.

HABITAT

Wet and cloudy evergreen forests or summit ericoid bushes and sclerophyll thickets at c. 1200-1900 m altitudes.

REMARKS

Peponidium crassifolium leaves are quite thick, slightly succulent and snap when broken. Leaves of this type are unknown in the tribe, and fresh material is unlikely to be confused with other species. The fused bracts are often hidden by the stipules or the flowers and are hard to observe. The species appears functionally dioecious as classically observed in this genus. However, the female inflorescences have five to ten flowers per inflorescence in contrast to other dioecious species, where the female individuals have solitary flowers or flowers in pairs. The generic placement of this species is based on the presence of the fused but not long acuminate bracts, a distinguishing character of Peponidium , as well as on molecular data (Razafimandimbison et al. unpubl. data). The species was previously recorded by Gautier (2002: 209) in the checklist of Manongarivo plants as Canthium sp. 2 . The author included several collections cited above, plus one (Rakotomalaza 97) not seen by us.

Figures

FIG. 1. — Peponidium crassifolium Lantz, Klack. & Razafim.: A, flowering branch; B, flower bud; C, female flower, one corolla lobe and corresponding part of tube removed, tangential longisection; D, part of female corolla; E, close-up of hair from inside of corolla. Scale bars: A, 1 cm; B-D, 3 mm; E, 0.5 mm.