Matelea trichopedicellata 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 : 31-32

Matelea trichopedicellata Krings & Morillo sp. nov. Figures 1A 2A 3A 4B 6

Latin.

A new species in the Matelea stenopetala complex, most similar to M. hildegardiana, but differing in part by leaf bases broadly cuneate to rounded (vs. attenuate to narrowly cuneate in M. hildegardiana), pedicels coarsely pubescent, with only glandular capitate trichomes ubiquitous, eglandular trichomes not ubiquitous, rather in two lines, ca. 0.3 mm long (vs. both glandular capitate and eglandular trichomes ubiquitous, eglandular trichomes to 0.07 mm long in M. hildegardiana), and corollas rose, lobes 4.1-4.2 mm long (vs. corolla green, lobes 4.9-5.5 mm long in M. hildegardiana).

Type.

BRAZIL. PARÁ: Rio Tocantins near Igarapé Cajazeirinha, approx. 30 km N of Itupiranga, 4°1'S, 49°21W, 1 Dec 1981 (fl & fr), D.C. Daly, R. Callejas, M.G. da Silva, E.L. Taylor, C. Rosario, & M.R. dos Santos 1619 (Holotype: NY!; Isotype: US!, MG, n.v., MO, n.v.).

Description.

Slender, woody vine. Stems moderately to densely pubescent, pubescence in two lines, eglandular trichomes coarse, retrorse, ca. 0. 4 mm long, glandular capitate trichomes sparse, spreading, ca. 0.05 mm long. Leaf blades narrowly to broadly elliptic, 5.7-7.8 × 2.0-4.5 cm, with 5-8 pairs of lateral veins, adaxial surface glabrous, midvein glabrous or pubescent, eglandular trichomes antrorse or spreading, ca. 0.3 mm long, glandular capitate trichomes spreading, ca. 0.05-0.07 mm long, abaxial surface glabrous, midvein glabrous or pubescent, eglandular trichomes antrorse or spreading, ca. 0.3 mm long, glandular capitate trichomes spreading, ca. 0.05-0.07 mm long, apices acuminate, bases broadly cuneate to rounded, margins entire, colleters 2-4, lanceolate, 0.3-0.4 mm long; petioles 0.9-1.3 cm long, moderately pubescent, pubescence ubiquitous, eglandular trichomes mostly restricted to the adaxial ridge, spreading to antrorse-spreading, ca. 0.4 mm long, glandular capitate trichomes spreading, 0.05-0.07 mm long. Inflorescence racemiform, apparently 1-2-flowered (1 flower open at a time); peduncles to 2.4 mm long, moderately pubescent, pubescence ubiquitous, eglandular trichomes antrorse or spreading, 0.2-0.25 mm long, glandular capitate trichomes spreading, 0.05-0.07 mm long; pedicels 4.4-5.2 mm long, moderately to densely pubescent, eglandular trichomes in two lines, spreading, ca. 0.3 mm long, glandular capitate trichomes ubiquitous, spreading, ca. 0.05-0.07 mm long. Calyx lobes lanceolate, reflexed or spreading, 1.4-1.7 × 0.4-0.6 mm, adaxial surface glabrous, abaxial surface moderately to densely pubescent, eglandular trichomes antrorse or spreading, ca. 0.18 mm long, glandular capitate trichomes absent or very sparse, spreading when present, ca. 0.06 mm long, apices obtuse, margins entire; colleters 1 per sinus, lanceolate, ca. 0.18 mm tall. Corolla rose (fide collectoris), subcampanulate at base, tube ca. 0.9 × 0.9 mm, lobes imbricate in bud, linear-lanceolate to oblong, spreading, 4.1-4.2 × 1.9-2.0 mm, not ocellate, marginally or laterally recurved, adaxial surface pubescent, eglandular trichomes spreading, ca. 0.06-0.08 mm long, glandular-capitate trichomes absent, abaxial surface moderately pubescent, eglandular trichomes antrorse, 0.15-0.18 mm long, glandular capitate trichomes absent or very sparse, spreading when present, 0.03-0.04 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) on the surface of the corolla lobes, not subtended by a stipe, margin crenulate-lobate, Cs rising to meet the lower portion of the anther, rising segment more or less perpendicular relative to the base, ca. 0.4 mm tall, margin entire, base somewhat swollen, crenulate-lobate, ligule an apical ridge, not free, Ci unlobed, not ligulate. Style-head 1.6-1.7 mm diam, stipe 0.45-0.65 mm tall, terminal style-head appendage absent. Pollinarium: corpuscula ca. 0.18 mm long, caudicles present, pollinia narrowly ovoid, ca. 0.45 × 0.2 mm. Follicles ovoid-fusiform (imm), ca. 6 x 1.3 cm. Seeds unknown.

Distribution.

Known only from the type, collected in the Brazilian Amazon, near Igarapé Cajazeirinha.

Ecology.

Currently known only from terra firme forest.

Phenology.

Collected in flower and fruit (imm) in December.

Etymology.

The specific epithet refers to the conspicuously pubescent pedicels.

Conservation status.

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

Discussion.

Matelea trichopedicellata shares with Matelea hildegardiana (apparently endemic to the Gran Sabana, Bolívar, Venezuela), pubescent abaxial and adaxial corolla surfaces, but differs from it in part by leaf bases broadly cuneate to rounded and coroll a lobes rose, 4.1-4.2 mm long (leaf bases attenuate to narrowly cuneate, and corolla lobes green, 4.9-5.5 mm long in Matelea hildegardiana ). Matelea trichopedicellata and Matelea hildegardiana both exhibit eglandular trichomes on the abaxial corolla lobe surface in which the lowest cell is usually filled with a green or dark substance. The upper cells of the trichomes are usually translucent.

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 6. Holotype of Matelea trichopedicellata (Daly et al. 1619, NY). Courtesy of the New York Botanical Garden.