Matelea brevistipitata Krings & Morillo, 2012

Krings, Alexander & Morillo, Gilberto, 2012, Two new species in the Matelea stenopetala complex (Apocynaceae, Asclepiadoideae) from the Guiana Shield and Amazonian Brazil, PhytoKeys 17, pp. 27-39 : 29-31

Matelea brevistipitata Krings & Morillo sp. nov. Figures 1D 2D 3C 4A 5

Latin.

A new species in the Matelea stenopetala complex, most similar to M. stenopetala, but differing in part by inflorescences with fewer flowers open at a time (usually 1(-2) vs. (2-) 3-4 (-5) in M. stenopetala), shorter peduncles (avg. 7 mm vs. avg. 15 mm in M. stenopetala), and stipe subtending the C(is) 0.12-0.22 mm [avg. 0.17 mm] tall (vs. 0.3-0.55 mm tall [avg. 0.37 mm] in M. stenopetala].

Type.

VENEZUELA. BOLÍVAR: Cerro Guaiquinima, Base Camp (Camp 7) along the Río Canapo, tropical lowland evergreen forest, near river, 5°N, 63°W, 310 m, 3 Feb 1990 (fl), B. Boom 9318 (Holotype: VEN!; Isotype: NY!).

Description.

Slender, woody vine. Stems glabrescent to moderately pubescent, pubescence in two lines, eglandular trichomes retrorse or spreading, of different size classes, largest ca. 0.5 mm long, smallest ca. 0.08 mm long, glandular capitate trichomes sparse to moderately dense, spreading, ca. 0.1 mm long. Leaf blades lanceolate, ovate, elliptic, oblong, obovate, or oblanceolate, 5.2-11.5 × 1.1-5.2 cm, with 5-7 pairs of lateral veins, adaxial surface glabrous, midvein glabrous to moderately pubescent, eglandular trichomes spreading, ca. 0.3 mm long, glandular capitate trichomes spreading, ca. 0.1 mm long, abaxial surface glabrous, midvein glabrous or sparsely pubescent, eglandular trichomes spreading, ca. 0.3 mm long, glandular capitate trichomes spreading, ca. 0.1 mm long, apices acuminate, bases cuneate to rounded, margins entire, colleters 3-4, lanceolate, 0.4-0.6 mm long; petioles 0.7-3.0 cm long, moderately pubescent, eglandular trichomes ubiquitous but most dense along adaxial ridge, spreading to antrorse, 0.4-0.5 mm long, glandular capitate trichomes ubiquitous, spreading, ca. 0.05 mm long. Inflorescence racemiform, 3-5-flowered (1(-2) flowers open at a time); peduncles 1.9-10 (-16) mm, sparsely to moderately pubescent, pubescence ubiquitous, eglandular trichomes rare, spreading or antrorse, ca. 0.2-0.25 mm long, glandular capitate trichomes spreading, ca. 0.1 mm long; pedicels 6.3-15.0 mm long, sparsely to moderately pubescent, pubescence ubiquitous, eglandular trichomes rare, spreading or antrorse, ca. 0.1 mm long, glandular capitate trichomes spreading, ca. 0.05 mm long. Calyx lobes linear to lanceolate, 1.1-2.0 × 0.25-0.45 mm, strongly reflexed, adaxial surface glabrous, abaxial surface sparsely to moderately pubescent, eglandular trichomes spreading or antrorse, ca. 0.3 mm, glandular capitate trichomes spreading, 0.03-0.05 mm long, apices obtuse, margins entire; colleters 1 per sinus, lanceolate, ca. 0.2 mm tall. Corolla green, greenish-yellow, or greenish-white (fide collectoris), subcampanulate at base, tube ca. 0.5-0.7 × 0.8-0.9 mm, lobes imbricate in bud, lanceolate to oblong, apparently spreading, 3.0-4.1 × 1.7-1.9 (-2.2) mm, not ocellate, adaxial surface pubescent, eglandular trichomes spreading, ca. 0.05-0.1 mm long, glandular-capitate trichomes absent, abaxial surface sparsely pubescent, eglandular trichomes rare, ca. 0.07 mm long, glandular capitate trichomes spreading, ca. 0.03 mm long, apices obtuse, margins entire. Faucal annulus (corolline corona or Ca) absent. Gynostegial corona of fused staminal (Cs) and interstaminal (Ci) parts, C(is) subtended by a short stipe, stipe 0.12-0.22 mm tall, Cs rising to meet the lower portion of the anther, rising segment at a distinctly acute angle relative to the base, 0.6-0.66 mm tall, margin entire, base somewhat swollen, entire or crenulate-lobate, ligule an apical ridge, not free, Ci unlobed, not ligulate. Style-head 1.2-1.4 (-1.7) mm diam, stipe 0.9-1.1 mm tall (incl. section subtending the C(is)), terminal style-head appendage absent. Pollinarium: corpuscula ca. 0.12-0.17 mm long, caudicles present, pollinia oblong, 0.36-0.4 × 0.15-0.25 mm. Follicles unknown. Seeds unknown.

Distribution.

Matelea brevistipitata isapparently endemic to the Guiana Shield in the Venezuelan states of Amazonas and Bolívar. It is very likely also present in the portion of Amazonian Brazil bordering those states. The distributions of Matelea brevistipitata and Matelea stenopetala appear to be largely parapatric. Both species occur in Bolívar (Venezuela), but this represents the easternmost edge of the range of Matelea brevistipitata and the westernmost edge of the range of Matelea stenopetala .

Ecology.

Known from swamp and riverine forests at low elevations, to 500 m.

Phenology.

Collected in flower in April, May, October, and November.

Etymology.

The specific epithet refers to the short stipe subtending the C(is).

Conservation status.

Currently, very little is known regarding the status of this species.

Discussion.

At a glance, Matelea brevistipitata can be distinguished from Matelea stenopetala by the few-flowered inflorescences, suggesting divergence in reproductive biology. Matelea stenopetala usually displays inflorescences with 3-4 open flowers, whereas Matelea brevistipitata displays inflorescences with only one open flower (rarely two) at a time. The floral display itself also differs between the two species. Although both exhibit calyx lobes strongly reflexed at anthesis, the lobes of Matelea stenopetala tend to be purple (sometimes also black or brown), presenting a striking contrast to the light colored corolla. In Matelea brevistipitata , in contrast, the calyx is usually green (frequently drying an olive green). While the adaxial corolla surface is pubescent in Matelea brevistipitata , it is only very rarely so in Matelea stenopetala . In fact, the vast majority of specimens of Matelea stenopetala seen exhibit corollas adaxially glabrous. It is worth noting that the rare exception (i.e., Mori 24547, US) otherwise exhibits character states typical of Matelea stenopetala , including long peduncles (13-16 mm), inflorescences with up to five flowers open at a time, and long stipes subtending the C(is) (0.35 mm; Fig. 2F ).

Specimens examined.

Venezuela: Amazonas. Camino entre caño Gruya y el pueblo de Gruya, bosque higrófilo macrotérmico ligeramente alterado en la margen del río Orinoco, 100 m, 8 Apr 1978 (fl), G. Morillo 7382 (VEN); Dept. Atabapo, Salto Yureba, Caño Yureba, Bajo Ventuari, 4°3'N, 66°1'W, 120-150 m, 24 Oct-4 Nov 1981 (fl), F. Delascio & F. Guánchez 10968 (MER,VEN); Dept. Atures, carretera Pto. Ayachucho-Samariapo, selva húmeda caliente, 13 Jan 1982 (fl), B. Stergios 3183 (VEN); Dept. Río Negro, between Río Marawinuma at base of Neblina (0°50'N, 66°9'W) and Río Baría, in swamp forest, a heavily overgrown series of small channels with black water, 8 May 1984 (fl), W.W. Thomas, A. Gentry & B. Stein 3401 (VEN, NY). Bolívar. Dept. Roscio, El Abismo, al norte del río Icabarú, bosque húmedo macrotérmico, 500 m, Oct 1985 (fl), F. Delascio 12503 (VEN); Expedición Proyecto I.R.N.R.S. a la cuenca alta del Río Caura (Hoja NB-20-14), selvas ribereñas del Caño El Pavo hasta arriba de la boca del Caño Maravene, 4°16'N, 64°9'W, 13-14 Apr 1988 (fl), B. Stergios 12315 (NY, US, VEN); Dist. Piar, Río Aparamán, at rapids of Yuray-merú, tributary of Río Acanan, SW base of Amaruay-tepui, E of Auyan-tepui, W of Aparaman-tepui, small tributary or river, densely forested with trees 20-30 m high, 5°55'N, 62°15'W, 500 m, 21 Apr 1986 (fl), B. Holst & R. Liesner 2661 (VEN, MO).

Figures

Figure 1. Abaxial corolla surface in the adaxially-pubescent-flowered members of the Matelea stenopetala complex. A Matelea trichopedicellata (based on Daly et al. 1619, US) B Matelea hildegardiana (based on Liesner 23469, U) C Matelea pakaraimensis (based on Mutchnik 122, US) D Matelea brevistipitata (based on Boom 9318, VEN) E Matelea stenopetala (based on Ek et al. 881, U) F Matelea stenopetala (based on Mori et al. 24547, US); Note difference in pubescence type between A-B (eglandular trichomes shown at arrows) and C-F (glandular capitate trichomes shown at arrows).

Figure 2. Gynostegial variation in the adaxially-pubescent-flowered members of the Matelea stenopetala complex. A Matelea trichopedicellata: i, flower, ii, coarsely pubescent pedicel, trichomes ca. 0.3 mm long (based on Daly et al. 1619, US) B Matelea hildegardiana (based on Davidse 4903, U) C Matelea pakaraimensis (based on Mutchnik 122, US) D Matelea brevistipitata (based on Boom 9318, VEN) E Matelea stenopetala (based on Ek et al. 881, U) F Matelea stenopetala (based on Mori et al. 24547, US). Note coronas at base of gynostegial columns sessile in A-C and raised off the surface of the corolla by a subtending stipe in D-F.

Figure 3. Foliar variation in some adaxially-pubescent-flowered members of the Matelea stenopetala complex. A Matelea trichopedicellata (based on Daly et al. 1619, US) B Matelea hildegardiana (based on Davidse 4903, US) C Matelea brevistipitata (based on Boom 9318, VEN) D Matelea stenopetala (based on Ek et al. 881, U).

Figure 4. Illustration of the leaves, inflorescences, and flowers of Matelea brevistipitata and Matelea trichopedicellata. A Matelea brevistipitata (based on B. Stergios 12315, NY) B Matelea trichopedicellata (based on Daly et al. 1619, US). Scale bars are 4 cm (Ai & Bi) and 0.4 mm (Aii & Bii).

Figure 5. Isotype of Matelea brevistipitata (Boom 9318, NY). Courtesy of the New York Botanical Garden.