Rhodocolea humbertii, Callm. & Phillipson, 2011

Callmander, Martin W. & Phillipson, Peter B., 2011, Four new species in the endemic genus Rhodocolea Baill. (Bignoniaceae) from Madagascar, Adansonia (3) 33 (2), pp. 311-321 : 312-314

Genus Rhodocolea Baill.

1. Rhodocolea humbertii

Callm. & Phillipson, sp. nov. ( Fig. 1 )

Haec species a congeneris foliis compositis 25-33 cm longis petiolo incluso, inflorescentia cauliflora sat parva atque calyce grandi denticulato facile distinguitur.

TYPUS. — Madagascar. Prov. d’Antsiranana, vallée de l’Andalangy, affluent de l’Andraronga (bassin de la Bemarivo du Nord-Est), 14°18’S, 49°43’E, 12-14.XI.1950, fl., Humbert & Capuron 24210 (holo-, P [ P00730612 ]!; iso-, B, K!, G [ G00303502 ]!, MO [ MO05033701 , 3640192 ]!, NY, PRE, TAN, WAG) .

PARATYPI. — Madagascar. Prov. d’Antsiranana, vallée de l’Antsahabe, affluent de la Lokoho, 14°27’S, 49°50’E, 10-11.III.1950, fl., Humbert 23345 ( MO [ MO3600880 ], P [2 sheets]). — À l’ouest de la rivière Manantenina, pentes orientales du Massif de Marojejy, 100-300 m, 14°29’S, 49°49’E, 14-15.IV.1949, Humbert 23407 ( P) . — Vallée inférieure de l’Androranga, affluent de la Bemarivo (nord-est) aux environs d’Antongondriha, Mont Anjenabe, 14°17’S, 49°46’E, 3.XI.1950, fl., Humbert & Capuron 24056 ( MO [ MO05033703 ], P) . — Vallée de l’Andalangy , affluent de l’Androronga (bassin de la Bemarivo du Nord-Est), 14°18’S, 49°43’E, 12-14.XI.1950, fl., Humbert & Capuron 24213 ( MO [ MO3640193 ], P) .

DESCRIPTION

Tree up to 10-15 m tall; dbh> 25 cm. Leaves imparipinnate, 25-33 × 10-12 cm (including petiole); rachis canaliculate, 0.2-0.3 cm in diam., dark green or straw-yellow when dried, glabrous; nodes slightly swollen, not conspicuous; petiole 5-7 cm long. Leaflets generally (7-)9-13; blade ovate, (5-)7(-9) × (2.5-)3(-3.5) cm, chartaceous, darker on the upper surface, glabrous; base shortly attenuate; apex acuminate, the acumen c. 10 × 4-6 mm; margins entire; midrib and secondary veins prominent on the both surfaces, reticulation visible; petiolule length 3-5 mm (lateral leaflets), up to 30 mm (terminal leaflets). Inflorescence, cauliflorous or terminal, a raceme up to c. 12 cm long, with 6-4 nodes each bearing 3-2 flowers; axis fine, patent, cylindric, c. 1 mm diameter, drying dark brown; bracts narrowly triangular, c. 3 × 1 mm, glabrous, persistent; peduncle <5 mm long; pedicel 2-3 cm long with a pair of minute persistent glabrous bracteoles at the base. Calyx campanulate, puberulent, 1.5-2 × 1.5- 1 cm, 5-lobed, with 5 prominent veins; lobes triangular, c. 4 × 4 mm, acute. Corolla tubular with 5 spreading lobes, c. 5.5 × 4 cm, pale pink [fide notes on Humbert 23345]; tube c. 3.5 × 1 cm, interior vinous, rather abruptly narrowed to c. 3 mm diameter in the basal 1/4; lobes rounded c. 1.5 × 1 cm; stamens 4, 2.2 cm long, filament densely pubescent at base, anthers c. 2 mm long, 2-locular; style 2.5 cm long, stigma laterally flattened, shortly bilobed. Fruit unknown.

DISTRIBUTION AND ECOLOGY

Rhodocolea humbertii is endemic to the mid-elevation evergreen humid forests around the Marojejy massif in northwestern Madagascar ( Fig. 2 ), but is not known from within the Marojejy National Park.

CONSERVATION STATUS

With an EOO of 83 km 2, an AOO of 27 km 2 and 5 subpopulations, none of which situated within the protected area network, Rhodocolea humbertii is assigned a preliminary status of Critically Endangered (CR B1ab[iii]).

REMARKS

Rhodocolea humbertii can be easily recognized by its long compound leaves (25-33 cm including petiole), rather small cauliflorous inflorescence (8-12 cm long) and by it large denticulate calyx (1.5-2 × 1-1.5 cm). Another new species described below, R. parvifoliolata growing the littoral forests of Masoala also bears similar large calices but the leaves and leaflets are much smaller in the latter (leaves: [6-]10-13 × 3-4.5 cm; leaflets: 2.5- 1.5 × 1- 0.6 cm in R. parvifoliolata vs. leaves: 25-33 × 10-12 cm; leaflets: [5-]7[-9] × [2.5-]3[3.5] cm in R. humbertii ).

Figures

FIG. 1. — Rhodocolea humbertii Callm. & Phillipson: A, branch; B, detail of base of petioles; C, cauliflorous inflorescence. Humbert & Capuron 24210 (holotype, P). Scale bars: A, 2 cm; B, C, 1 cm. Drawing Roger Lala Andriamiarisoa.

FIG. 2. — Distributions of the Rhodocolea new species mapped on the bioclimatic zones of Madagascar (after Cornet 1974; see Schatz 2000): R. humbertii Callm. & Phillipson (Δ), R. magnifica Callm. & Phillipson (-), R. parvifoliolata Callm. & Phillipson (*), and R. ranirisonii Callm., Phillipson & L. Gaut. (•).