Cynometra steyermarkii Rados., 2019

Radosavljevic, Aleksandar, 2019, The rise of Cynometra (Leguminosae) and the fall of Maniltoa: a generic re-circumscription and the addition of 4 new species, PhytoKeys 127, pp. 1-37 : 19-22

3. Cynometra steyermarkii Rados. sp. nov. Figures 8 , 9 , 10

Type.

VENEZUELA. Miranda: Distrito Brión, Selva siempre verde a lo largo de la quebrada afluente del río Aricagua, 3.9 km oeste del Pueblo Seco, 1.6 km oeste de Aricagua, 75 m alt., 24-25 March 1973, [fl, fr], J. A. Steyermark & V. Carreño Espinoza, 106937 (holotype: US; isotypes: F, VEN n.v.).

Description.

Tree to 25 m tall; bark not seen, sapwood reddish; branchlets glabrous, lenticelate. Stipules not seen. Leaves bifoliolate, axes glabrous; petioles 6.5-9.0 mm long, 2.0 mm wide, transversely corrugated; petiolules 2.0-3.0 mm long, 1.0 mm wide, transversely corrugated; leaflets, coriaceous, elliptic to slightly obovate, asymmetric, primary vein eccentric, proximal side 2.3-3.1 times wider than distal, 5.7-7.1 cm long, 2.7-3.6 cm wide, discolorous, abaxial and adaxial surface glabrous, primary venation pinnate, secondary venation brochidodromous-eucamptodromous, 2(-3) basal acrodromous veins, decurrent to primary vein, prominent abaxially, slightly raised adaxially, tertiary venation visible on abaxial surface without magnification, margins entire, apex obtuse, usually rounded but occasionally acuminate (to 3.0 mm), retuse, mucronate, base oblique, acute, distal side strongly cuneate, proximal concave to convex, decurrent to petiolule, single laminar gland present on some leaflets, abaxial, near basal margin of proximal lamina and insertion point of petiolule, typically adjacent to tertiary veins, crateriform, 0.5 mm in diameter. Inflorescence an axillary raceme, bracteate, axes densely ferrugino-puberulent; peduncle together with rachis to 6.0 mm long, flowers spirally arranged, 15 per raceme; pedicels 5.5-6.0 mm, pubescent, accrescent in fruit; bracts subtending individual flowers, scale-like, deciduous, lustrous, brown, broadly elliptical, strongly convex 1.0-2.0 mm long, 1.5-2.5 mm wide, striate, abaxial surface with appressed pubescence along medial surface and along margins, glabrous adaxially; bracteoles paired, inserted near base of pedicel, subopposite, linear to oblanceolate, 2.5-3.0 mm long, 0.75 mm wide, acute at apex, densely pubescent on abaxial surface, less so adaxially. Flowers bisexual, radially symmetric, pentamerous, delicate; hypanthium much reduced, less than 0.5 mm deep, with a few scattered hairs on abaxial and adaxial surface; sepals 4, imbricate, reflexed, slightly unequal, white, petaloid, oblong to obovate, 2.5-3.5 mm long, 1.0-1.5 mm wide, faintly striate, appressed pubescence on abaxial surface near insertion point and along central axis; petals 5, equal, white, oblanceolate, 3.5-4.5 mm long, 1.0-1.5 mm wide, pinnate venation; stamens 10, filaments appearing free but possibly connate for approximately 0.25 mm at base, subequal, 4.0-5.5 mm long, anthers dorsifixed, versatile, longitudinal dehiscence, ellipsoid, to 0.75 mm long, glabrous; ovary centrally inserted, free, sessile, obliquely elliptical, 2.5-4.0 mm long, 1.5-3.0 mm wide, pubescent at base and along suture, becoming glabrous with age, style apical, 1.5-2.5 mm long, glabrous, eccentric, stigma capitate. Legume indehiscent, globose, shortly apiculate (to 0.75 mm), 1.5 cm in diameter, surface of granulose, with very short pubescence, wall of pericarp up to 2.0 mm thick, brown. Seeds 1 per pod (1 ovule per ovary based on dissections), dark brown.

Distribution and ecology.

Known from a single collection made in Miranda State, Venezuela. The species was collected growing along a small stream in the foothills of the Cordillera de la Costa at approximately 75 m above sea level. While much of this region is covered in xeric shrublands and thorn forests, this site corresponds to a low gallery forest growing along a tributary of the Río Aricagua.

Phenology.

The type material was collected at the end of March with late flowers and nearly mature fruit.

Etymology.

The specific epithet honours Dr. Julian A. Steyermark, the collector of the type material and a prolific collector of neotropical plants. Over the course of his career, he made over 130,000 collections and greatly advanced our knowledge of the Venezuelan flora.

Additional specimens examined.

None.

Notes.

Cynometra steyermarkii is the only confirmed species of Cynometra known from the forests of the Cordillera de la Costa in northern Venezuela and one of two species of Venezuelan Cynometra growing outside of the Guayana region. Henri Pittier (1926) published an account of a Cynometra growing in the hills outside of Caracas, Cynometra sphaerocarpa Pittier, for his Manual de las plantas usuales de Venezuela. While the description is valid, according to the rules of nomenclature in effect at the time, he failed to designate a type or list any collections that may correspond to this taxon. In his 1958 revision, Dwyer was unable to locate any material that could be assigned to this taxon and pointed out the limited utility of Pittier’s description - 'Las hojas inequilaterales, lanceadas, largamente atenuadas y glabras … Los frutos son subglobosos, de 3.5-4 cm. de diametro y contienen una sola semilla [Leaflets asymmetric, lanceolate, largely attenuate and glabrous. The fruits are sub-globose, 3.5-4 cm in diameter, and contain a single seed]. ’– which could very well describe any number of Cynometra species, including C. steyermarkii . A full set of Pittier’s duplicates from this publication should be deposited in the United States National Herbarium (US), but after exhaustive searches in the US collections and a study of both Pittier’s archives and the museum registrar’s records, I was unable to find any material that could be attributable to C. sphaerocarpa . Curators at Herbario Nacional de Venezuela graciously searched through material housed there, but were also unsuccessful. While it is possible that C. steyermarkii and C. sphaerocarpa are the same taxon, without Pittier’s original material, it is impossible to know for sure. Rather than leave this unresolved, it is more useful to describe a new species with good type material.

This species bears a resemblance to Cynometra spruceana var. phaselocarpa Benth. owing to the obtuse nature of the leaf apices. However, C. steyermarkii often has slightly acuminate apices. Furthermore, both the rachis and pedicels of the inflorescence are much shorter in C. steyermarkii than in typical C. spruceana var. phaselocarpa .

Figures

Figure 8. Illustration of Cynometra steyermarkii. A Habit, flowering branch B habit, fruiting branch C leaf base, showing basal acrodromous veins arising from leaflet pulvinus D inflorescence rachis, showing bracts and bracteoles; pedicels removed to show structure E buds with imbricate bracts F flower G bract H bracteoles I sepals J petal K longitudinal section of flower showing single ovule and much reduced hypanthium; sepals, petals and stamens removed. A-K Steyermark et al. 106937, US.

Figure 9. Photograph of the holotype of Cynometra steyermarkii, sheet one of two (Steyermark et al. 106937, US).

Figure 10. Photograph of the holotype of Cynometra steyermarkii, sheet two of two (Steyermark et al. 106937, US).