Beguea betamponensis G.E. Schatz, Gereau & Lowry

George E. Schatz, Roy E. Gereau & Porter P. Lowry Ii, 2017, A revision of the endemic Malagasy genus Beguea (Sapindaceae), Candollea 72 (1), pp. 45-65 : 53

4. Beguea betamponensis G.E. Schatz, Gereau & Lowry , spec. nova ( Fig. 6 ).

Typus: MADAGASCAR. Prov. Toamasina: Atsinanana Region, RNI de Betampona, piste principale , 17̊55’S 49̊13’E, 300-400 m, 30.XI.1994, fl., Andrianarisata et al. 246 (holo-: MO-6704232! ; iso-: P [P06168886]! TAN!).

Haec species a congeneris indumento stellato-fasciculato, foliolis coriaceis marginibus valde revolutis apice rotundatis atque inflorescentia raro ramosa distinguitur.

Tree c. 13 m tall; young stems with dense golden stellate-fasciculate indument, glabrescent. Petioles 2.8- 5.4 cm, with sparse strongly appressed golden stellate indument. Leaves with 3-8 subopposite to alternate leaflets; rachis 2.7-10 cm, keeled above, glaucous with sparse, strongly appressed golden stellate indument; petiolule 1-5 mm or leaflets sometimes subsessile, with sparse golden stellate-fasciculate indument, glabrescent; leaflet blade 3.2-10 × 1.5-3.5 cm, oblanceolate to occasionally elliptic, very coriaceous, flat in pressed material, glabrous and glossy above, glabrous and dull below, base asymmetrical, acute to cuneate, margins strongly revolute with up to 3 mm rolled under in dried material, apex rounded, midvein slightly raised above, distinctly raised below, slightly glaucous, with sparse appressed golden stellate indument, secondary veins 12-16 per side, flat to slightly impressed above, raised below, tertiary venation slightly raised and evident above. Inflorescence axis 6- 19 cm, unbranched, or bifurcating towards the apex, reddish, essentially glabrous with very sparse golden stellate-fasciculate indument; bracts c. 0.3 mm, triangular; pedicels 2.5-3.5 mm, 0.3-0.4 mm in diam., densely golden strigulose and also with appressed golden stellate-fasciculate trichomes. Male flowers with a cupulate, 5- or 6-lobed calyx, the lobes c. 0.5 × 0.5 mm, triangular, acute, glabrous outside, densely golden setaceous inside; stamens 8, filaments c. 4.5 mm, glabrous except for sparse trichomes toward the base, anthers c. 1.1 × 0.4 mm, ellipsoid; disc and pistillode densely golden setaceous, the trichomes to 0.5 mm. Female flowers not seen. Fruit not seen.

Conservation status. – Although Beguea betamponensis is known only from the fairly well-protected Betampona Strict Nature Reserve ( Fig. 4 ), its current status with regard to population size and reproduction, and also the potential negative impact from invasive strawberry guava ( Psidium cattleyanum Sabine ), is unknown. With a restricted AOO and the potential threat from such an aggressive invasive, which could rapidly push the species to “Critically Endangered” or “Extinct” status, B. betamponensis is here assigned the category of “Vulnerable” [VU D2] using the IUCN Red List Criteria ( IUCN, 2012).

Notes. – Beguea betamponensis is known only from the type collection in humid forest at the Betampona Strict Nature Reserve ( Fig. 7 ), where it is sympatric with B. apetala . It can be easily distinguished from B. galokensis , with which it shares an indument of tufts of very short golden stellate-fasciculate trichomes, by its very coriaceous leaflets with strongly revolute margins, rounded apex lacking a mucro, and impressed secondary veins (vs subcoriaceous leaflets with slightly revolute margins, acute to acuminate apex with a distinct mucro, and flat to slightly raised secondary veins) and its occasionally branched inflorescences (vs unbranched inflorescences) ( Fig. 6 ).

Figures

Fig. 4. – Geographic distribution of Begueo opetolo Capuron (circles), B. birkinshowii G. E. Schatz, Gereau & Lowry (stars), B. boreolis G. E. Schatz & Lowry (diamond), B. tsorotononensis G. E. Schatz, Gereau & Lowry (squares) and B. turkii G. E. Schatz, Gereau & Lowry (triangles), mapped on the bioclimatic zones of Madagascar (after CORNET, 1974; see SCHATZ, 2000).

Fig. 6. – Begueo betomponensis G. E. Schatz, Gereau & Lowry. A. Flowering branch; B. Portion of inflorescence axis; C. Detail of flower at anthesis. [Andrionorisoto et ol. 246, MO] [Drawing: R. L. Andriamiarisoa]

Fig. 7. – Begueo birkinshowii G. E. Schatz, Gereau & Lowry. A. Flowering branch; B. Detail of flower at anthesis; C. Portion of inflorescence axis. [Birkinshow 159, MO] [Drawing: R. L. Andriamiarisoa]