Matayba ayangannensis Acev.-Rodr.,, 2011

Acevedo-Rodriguez, Pedro, 2011, Four new species of Sapindaceae from the Guianas, PhytoKeys 7, pp. 11-20 : 11-12

Matayba ayangannensis Acev.-Rodr., sp. nov. Fig. 1A-I

Latin

Frutex 2.5 metralis; foliis 4-6 foliolatis; foliolis alternis vel sub oppositus, discolores, ellipticus, apice rotundatis retusisque; calyce tomentelli, petalis obovatis.

Type.

Guyana. Cuyuni-Mazaruni. Mt. Ayanganna, S.S. Tillet, C.L. Tillet, & R. Boyan 45080 (holotype: NY!; isotypes: MO!, US!).

Description.

Shrub to 2.5 m tall. Stems glabrous, striate. Leaves paripinnate; petiole plus rachis 2-6.5 cm long, slightly flattened adaxially, striate, puberulent; petiolules ca. 5 mm long, pulvinate at base; leaflets (4) 6, 2.5-4.5 × 1.2-2.3 cm, opposite or sub-opposite, obovate, oblanceolate or nearly elliptic, rigidly coriaceous, brittle, discolorous (abaxial surface drying brownish), adaxially glabrous, abaxially puberulent, especially along midvein, the base obtuse, symmetrical, the apex emarginate or less often rounded, the margins entire, slightly revolute; abaxially the midvein prominent, secondary and tertiary veins inconspicuous, reticulate. Thyrses 8-18 cm long, axillary, on distal portion of branches, paniculate, with ferruginous-pubescent and slightly angled axes. Flowers in simple dichasia; pedicels ca. 2 mm long, pubescent. Calyx brownish yellow, ferruginous-pubescent, ca. 1 mm long, the lobes 0.5-0.7 mm long, ovate; petals ca. 2 mm long, yellowish white, obovate, emarginate at apex, lanose mostly along margins; appendages 2, ca. 1 mm long, sericeous-tomentose, supra basal; disc glabrous, pulvinate; stamens 2-2.5 mm long, the filaments lanose on lower half; ovary tomentulose, the style subcapitate. Capsules not known.

Distribution and ecology.

Known only from the type collection in Guyana, in low forest.

Discussion.

Matayba ayangannensis looks vegetatively similar to Matayba yutajensis Steyerm., as both species are shrubs and have leaflets with retuse apex and reticulate venation; however, Matayba ayangannensis differs from the latter by its leaves with (4) 6, discolorous, brittle leaflets that are 2.5-4.5 cm long (vs. 2(4), concolorous, coriaceous, 10-18 cm long), and by its ferruginous-pubescent calyx, ca. 1 mm long (vs. glabrous or sparsely strigose at base and ca. 3.5 mm long).

Etymology.

The epithet refers to Mt. Ayanganna where the type collection was made.

Figures

Figure 1. Matayba ayangannensis A Branch with staminate flowers B Branch with pistillate flowers C Distal portion of leaf rachis showing distal process and bases of 4 leaflets D Staminate flower E Staminate flower with part of perianth removed to show nectary disc, stamens and pistillode; detail of pistillode F Pistillate flower G Pistillate flower with part of perianth removed to show nectary disc and gynoecium; detail of staminode H Abaxial, adaxial and lateral views of petal with appendages I Pistillate flower with partly developed gynoecium, l. s. of same. All from Tillet 45080 (NY).