Beguea borealis G.E. Schatz & 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 : 56-58

6. Beguea borealis G.E. Schatz & Lowry , spec. nova

( Fig. 8 ).

Typus: MADAGASCAR. Prov. Antsiranana: DIANA Region, Montagne des Français , forêt d’Ampitiliantsambo , à 3 h. de marche à pied, à l’E d’Andranomanitra, 12̊23’13’’S 49̊23’04’’E, 205 m, 14.I.2005, fl., Randrianaivo et al. 1163 (holo-: P [ P04765740 ]!; iso-: MO, TAN!).

Haec species a congeneris caulibus petiolis petiolulisque indumento aureo dense tomentulosis atque foliolis conduplicatis 4 ad 6 venis secundariis in quoque latere 7 ad 10 distinguitur.

Tree c. 12 m tall, bole c. 15 cm in diam.; stems densely golden tomentulose, glabrescent. Petioles 1.7-3.6 cm, densely golden tomentulose. Leaves with 4-6 subopposite to opposite leaflets; rachis 0.2-2.1 cm, not keeled, densely golden tomentulose; petiolule 2-4 mm, light gray-tan tomentulose; leaflet blade 3.3-4.6 × 1.6-2.4 cm, elliptic (occasionally very slightly ovate or obovate), subcoriaceous, nearly always conduplicate and folded along the midvein in pressed material, glabrous and glossy above, glabrous below except very sparsely tomentulose at the base, base symmetrical, cuneate to acute, margins flat, minutely thickened but not revolute, apex acuminate, the acumen rounded, midvein flat above, sparsely tomentulose, raised below, sparsely tomentulose towards the base, secondary veins 7-10 per side, slightly raised above and below, tertiary venation raised on both surfaces. Inflorescence axis 1.5-9.7 cm long, c. 1 mm in diam. at base, unbranched, sparsely tan sericeous; bracts c. 0.2 mm, triangular, adaxially concave; pedicels usually paired on a common peduncle to 1 mm, sometimes solitary and epedunculate, 0.5-1.5 mm, moderately to densely tan sericeous. Male flowers with a cupulate, 5- to 7-lobed calyx, the lobes 0.2-0.3 × 0.3-0.6 mm, broadly triangular, sparsely tan sericeous outside; disc glabrous to sparsely white granular-farinose; stamens 8 (or 9), filaments c. 2 mm, with sparse spreading trichomes along basal third, anthers 0.7-0.8 × 0.3-0.4 mm, oblong; pistillode 0.2-0.3 mm high, 0.2-0.3 mm in diam., hemispherical, covered with short appressed trichomes. Female flowers not seen. Fruit not seen.

Etymology. – The epithet borealis refers to the northernmost occurrence of the genus Beguea in Madagascar.

Vernacular name. – “Gavoala”.

Conservation status. – While Beguea borealis occurs within the recently decreed Montagne des Français (Ambohitr’Antsingy) protected area, it was collected adjacent to a clearing used as pasture and subject to potential burning, threats that may continue despite the new protected status. Therefore, with a restricted AOO and plausible threats that could rapidly push the species to Critically Endangered or Extinct status, B. borealis warrants a preliminary assessment of “Vulnerable” [VU D2] using the IUCN Red List Criteria ( IUCN, 2012).

Fig. 8. – Begueo boreolis G.E. Schatz & Lowry. A. Flowering branch; B. Leaflet (lower surface); C. Portion of inflorescence axis; D. Two flowers (one with filaments only partially expanded); E. Detail of flower at anthesis.

[Rondrionoivo et ol. 1163, P]. [Drawing: R.L. Andriamiarisoa]

Notes. – Beguea borealis is known only from the type specimen from the Forêt d’Ampitiliantsambo within the Montagne des Français massif ( Fig. 4 ). It can be distinguished from B. apetala , with which it shares conduplicate leaflets that are usually folded along the midvein in pressed material, by its leaflets with a symmetrical base, the margins flat and minutely thickened but not revolute (vs leaflets with a distinctly asymmetrical base and strongly revolute margins) ( Fig. 8 ).

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. 8. – Begueo boreolis G. E. Schatz & Lowry. A. Flowering branch; B. Leaflet (lower surface); C. Portion of inflorescence axis; D. Two flowers (one with filaments only partially expanded); E. Detail of flower at anthesis. [Rondrionoivo et ol. 1163, P]. [Drawing: R. L. Andriamiarisoa]