Combretum longistipitatum Jongkind, 2018

Jongkind, Carel C. H., 2018, Novitates Gabonenses 89: Combretum longistipitatum Jongkind, sp. nov. (Combretaceae), a new liana species from Gabon, Adansonia (3) 40 (9), pp. 131-134 : 132-134

Combretum longistipitatum Jongkind , sp. nov.

(Figs 1; 2)

TYPUS. — Gabon. Ogooué-Maritime, Doudou Mountains, Nord- Ouest de Doussala , 2°28.4’S, 10°33.9’E, 120 m., fr., 25.IX.2000, Bourobou, Nzabi, Nziengui & Mayombo-Nzengue 495 (holo-, WAG [ WAG.1477676]!; iso-, LBV); only material known .

DIAGNOSIS. — This liana differs from other Combretum subg. Combretum species by the exceptional long stipe of the fruit compared to the size of the wings. The samara is in diameter only 1.5-2 × the length of the stipe The leaf blade differs from that of most other Combretum subg. Combretum species by its relatively low number of main lateral nerves, its conspicuous hair-tuft domatia and its acute, not acuminate, apex.

ETYMOLOGY. — The specific epithet refers to the long stipe of the fruit.

HABITAT AND DISTRIBUTION. — Lowland forest in the Ogooué- Maritime Province of Gabon (Fig. 1).

CONSERVATION STATUS. — Combretum longistipitatum , sp. nov. is known from a single locality. Following the IUCN Red List Categories and Criteria ( IUCN 2012) it should be considered as “Critically Endangered” under Criterion B. However, there is still a lot of botanically poorly known forest in the Moukalaba- Doudou National Park and it is highly unlikely that the only known collection is from the last plant of an almost extinct species. Lianas are easily overlooked in botanical surveys and many such Combretum species usually flower and fruit high up in the forest canopy. On the other side, I have been in different parts of Gabon specially looking for Combretum and would have col- lected C. longistipitatum , sp. nov., fertile or sterile, if it had been encountered. Amongst the more than 700 Combretum specimens collected in Gabon ( Jongkind 2006a) there is only one from this species. Hence it is not likely that C. longistipitatum , sp. nov. is a common or widespread species.

Still, without more data it not possible to correctly select an IUCN category of threat, for the moment the species has to be listed as Data Deficient (DD).

NOTE

Of the flowers only a few remnants were found, persisting amongst the fruits. The upper receptacle is relatively short and petals are present. The presence of petals is taxonomically significant because there are several species in Combretum subg. Combretum without petals. The flower remnants are too small and old to clearly establish the shape or the indumentum of the receptacle and petals. The new species can not be included in the key to the species in the Flore du Gabon ( Jongkind 1999) because most flower characters are still not known.

DESCRIPTION

Liana. Twigs covered with dense tiny ordinary hairs and scales. Leaves opposite; petiole 5-12 mm long; blade elliptic, 5.5-11.5 × 3-7.5 cm, below with scattered small hairs and small, inconspicuous scales, midrib impressed above, prominent beneath, 4 or 5 pairs of main lateral nerves most with conspicuous hairy domatia in the axil below, tertiary nervation widely spaced scalariform with a reticulate pattern in between, base cuneate, apex acute with a mucronate tip. Scales inconspicuous, c. 20 µm in diameter, with c. 8 radial walls. Inflorescence a spike 2-3.4 cm long. Flower 4-merous, with petals. Fruit 22-27 mm wide, a samara with 4 papery wings, subcircular in outline, with scattered tiny hairs and inconspicuous scales, stipe 11-18 mm long, slender and flexible. Cotyledons 2, irregularly folded in seed.