Cynometra tumbesiana 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 : 22-27

4. Cynometra tumbesiana Rados. sp. nov. Figures 11 , 12

Type.

ECUADOR. El Oro: Bosque Petrificado Puyango, dirt track from information centre towards the camping area near Río Puyango, 03°52'30"S, 80°05'01"W, 450 m alt., 6 May 1997 [fl], B.B.Klitgaard et al. 507, (holotype K; isotype AAU n.v., LOJA n.v., NY, QCNE n.v., US).

Description.

Tree 10-25 m tall; bark grey-brown, lenticelate, inner bark red; branchlets with short pubescence when young, becoming glabrous with age. Stipules not seen. Leaves bifoliolate, axes ferrugino-puberulent when young, glabrous when mature; petioles 4.5-6.5 mm long, transversely corrugated; petiolules 1.5-2.0 mm long, inconspicuous; leaflets oblong-ovate to elliptic to oblong-obovate, occasionally slightly falcate or sub-trapeziform, strongly asymmetric, primary vein eccentric, proximal side 1.8-2.5 times wider than distal, 4.1-7.9 cm long, 2.5-3.3 cm wide, discolorous, abaxial surface sparsely pubescent on midvein, secondary veins and along basal margin, adaxial surface glabrous, primary venation pinnate, secondary venation brochidodromous-eucamptodromous, 2-3 (-4) basal acrodromous veins, decurrent to primary vein, prominent abaxially, flush to slightly raised adaxially, tertiary venation visible on abaxial surface at 10 × magnification, margins entire, apex acute, acuminate (to 6.0 mm), retuse, mucronate, base oblique, distal side acute, convex to cuneate, proximal side obtuse, concave to rounded, decurrent to petiolule, single laminar gland present, abaxial, near basal margin of proximal lamina and insertion point of petiolule, typically adjacent to tertiary veins, crateriform, 1.0 mm in diameter. Inflorescence a cluster of (1 –)2– 3 axillary racemes, bracteate, axes ferrugino-puberulent at base, hairs becoming scattered at distal end; peduncle together with rachis 4.5-8.0 mm long, flowers spirally arranged, 12-20 per raceme; pedicels 5.0-9.0 mm, pubescent initially but soon glabrescent, accrescent in fruit; bracts subtending individual flowers, scale-like, deciduous, leaving behind a lunate scar on the rachis, lustrous, brown, broadly elliptical, strongly convex 1.5-2.5 mm long, 1.5-2.5 mm wide, striate, abaxial surface with scattered appressed pubescence at apex and along margins, glabrous adaxially; paired bracteoles inserted 0.5-1.0 mm from base of pedicel, subopposite, oblong-lanceolate, 2.0-2.5 mm long, 1.0 mm wide, convex at apex, pubescent along margins and medial abaxial surface. Flowers bisexual, radially symmetric, pentamerous, delicate; hypanthium cupular, 1.0-1.5 mm deep, fleshy, with a few scattered hairs on abaxial and adaxial surface; sepals 4, imbricate, reflexed, unequal, adaxial sepal usually 2 times as wide as the others, white, petaloid, broadly ovate to elliptical, 3.0-4.5 mm long, 1.5-4.0 mm wide, striate, scattered pubescence at base; petals 5, erect, equal to subequal, white, spathulate to oblanceolate, 3.5-5.5 mm long, 1.0-2.0 mm wide, glabrous but with a tuft of hair at base of claw; stamens 10, filaments free, subequal, 5.5-7.5 mm long, white, anthers dorsifixed, versatile, longitudinal dehiscence, suborbicular, to 1.5 mm long, yellow-orange, glabrous; ovary centrally inserted in hypanthium, free, stipitate, obliquely elliptical, 4.0-5.0 mm long, 2.0-2.5 mm wide, densely pilose, stipe 0.5-1.0 mm long, style apical, 3.0-4.0 mm long, glabrous, eccentric, geniculate, stigma capitate. Legume indehiscent, oblong, weakly apiculate, slightly compressed, up to 5.2 cm long, 4.0 cm wide, 3.9 cm thick, surface of valves finely textured, granulose, wall of pericarp up to 4.0 mm thick, deep brown colour at maturity. Seeds 1 per pod, filling entire cavity, dark brown.

Distribution and ecology.

Cynometra tumbesiana occurs in the seasonally dry tropical forests of western and southern Ecuador and north-western Peru (a single collection) at elevations between 100-800 m ( Figure 3 ). These habitats are severely threatened regionally and globally due to extensive human modification of the landscape and, as a result, this species now exists primarily as isolated fragments. While C. tumbesiana is locally abundant at a few sites, it is currently known from less than 10 localities, several of which are within 5 km of each other.

Phenology.

Flowering specimens have been collected in May and December to January; fruiting specimens have been collected in August and January to February. Cynometra tumbesiana is one of the few woody taxa in the dry forests that retain their leaves during the dry season.

Etymology.

The specific epithet refers to the Tumbes region, where the type specimen was collected and where many of the known localities occur.

Additional specimens examined.

ECUADOR. El Oro: Bosque Petrificado Puyango, dirt track from information centre towards the camping area near Río Puyango, 03°52'30"S, 80°05'01"W, 450 m alt., 23 Aug 1996 [fr], B.B. Klitgaard et al. 325 (AAU n.v., K, LOJA n.v., NY, QCNE n.v.); 26 Feb 1997 [fr], B.B. Klitgaard et al. 424 (AAU n.v., K, LOJA n.v., NY, QCNE n.v.). [ Piñas]: Piedras, about 3 km. along new trail, 18 Jun 1943 [st], E.L. Little, Jr. 6622 (US). Guayas: [without specific locality] 2 Feb 1962 [fr], A.J. Gilmartin 551 (US). Guayaquil: Bosque Protector Cerro Blanco, 15 km west of Guayaquil, summit area of Cerro Blanco, 2°10'S, 79°58'W, 370 m alt., 27 Feb 1996 [fr], D. Neill & T. Núñez 10453 (MO, US); Bosque Protector Cerro Blanco, along road from visitor centre to "Cusumbo Top", 80, 01 W, 2 10 S, 400 m alt., 7 Aug 1996 [im fr], D. Neill, T. Núñez & J. Machuca 10636 (MO); Bosque Protector Cerro Blanco, carretera a Salinas, km 15, 2°10'S, 79°58'W, 400 m alt., 21-25 Jan 1992 [fr], D. Rubio & Galo Tipaz 2365 (MO). Isidro Ayora: Reserva Ecológica Manglares Churute, carretera Guayaquil–Puerto Inca, sector norte del Cerro Masvale, 2°20'S, 79°50'W, 200-300 m alt., May 1993 [fl], T. Núñez & A. Hernández 147 (MO). Manabi: [Puerto López]: Estero Perro Muerto, Machalilla National Park, below San Sebastian, 1°36'S, 80°42'W, 400-420 m alt., 23 Jan 1991 [fl], A. Gentry & C. Josse 72677 (MO); [San Vicente]: [hacienda] El Recreo, [fl], H.F.A. von Eggers 15752 (US). PERU. Tumbes: Zarumilla: Dtto. Matapalo, Campo Verde a 68 km de. Tumbes, 700-800 m alt., 24 Dec 1967 [fr], J. Schunke V. 2411 (F, NY, US).

Notes.

This species, restricted to the few remaining fragments of dry tropical forest in western Ecuador and the Tumbes region of Peru, has been mistakenly referred to as Cynometra crassifolia Benth. for many years. However, closer examination shows it to be quite distinct from this taxon. The type specimen of C. crassifolia was collected in Brazil by Portuguese naturalist Alexandre Rodriques Ferreira during his exploration of the Amazonian region of Brazil from 1783-1792. His collections, along with many others housed at Lisbon, were expropriated by Étienne Geoffroy Saint-Hilaire and transferred to Paris during Napoleon’s occupation of Portugal. There, it was seen by George Bentham, who described Cynometra crassifolia in 1840. The primary differences between C. tumbesiana and C. crassifolia are found in the inflorescences: the racemes of C. crassifolia have larger flowers, longer pedicels and a more robust pedicel and rachis, but fewer individual flowers than those of C. tumbesiana . The flowers of C. tumbesiana are indeed relatively small compared to the other neotropical Cynometra species, though they are densely clustered on the short rachis of the inflorescence. The leaflets of C. tumbesiana are also less distinctly acuminate than those of C. crassifolia and have a less obtuse base; the base of the leaflet in C. crassifolia can appear to be almost truncate.

Some taxonomists have placed the Ecuadoran Cynometra within C. bauhiniifolia Benth., with a few treating C. crassifolia as a synonym of C. bauhiniifolia ( Neill et al. 1999). In the first case, while C. tumbesiana does bear a passing resemblance to some forms of C. bauhiniifolia , the pod of C. bauhiniifolia is many times smaller and the surface of the valves is corky and deeply rugose. In the latter case, it is difficult to find justification for synonymising the two with the exception that C. bauhiniifolia has been a dumping ground for hard to place taxa within the genus and does occasionally occur in drier habitats. The leaflets, inflorescences and fruits all differ. Instead, the type material of C. crassifolia seems to be very similar to C. longicuspis Ducke, a widespread species from the moist lowland forests of Brazil.

Cynometra tumbesiana is morphologically and ecologically similar to C. oaxacana Brandegee from western and southern Mexico. The two can be distinguished by the narrower and more acuminate leaflets and larger fruits in C. tumbesiana . The inflorescences of C. oaxacana are also slightly more robust and have a more obvious pubescence. Both species are found in dry habitats (uncommon amongst the neotropical species of Cynometra ), though C. tumbesiana is found in much drier sites.

Figures

Figure 3. Distribution of Cynometra cerebriformis, C. dwyerii, C. steyermarkii and C. tumbesiana.

Figure 11. Illustration of Cynometra tumbesiana. A Habit B leaflet base, showing laminar gland C flower D inflorescence rachis, showing bracts and bracteoles; pedicels removed to show structure E fruit, dissected to show single seed filling entire cavity. A-D Klitgaard et al. 507, K; B Neill & Nunez 10453, US.

Figure 12. Photograph of the holotype of Cynometra tumbesiana (Klitgaard et al. 507, K).