Phaeostemma surinamensis Morillo & Krings, 2014

Morillo, Gilberto & Krings, Alexander, 2014, A new species and a new combination in Phaeostemma (Apocynaceae, Asclepiadoideae, Gonolobinae), PhytoKeys 33, pp. 41-50 : 44-46

Phaeostemma surinamensis Morillo & Krings sp. nov. Figures 3 -6

A new species of Phaeostemma E. Fourn., morphologically similar to Phaeostemma fucata (Woodson) Morillo & Krings, but differing from the latter among other characters, by leaf blades thinner, membranous, narrowly elliptic to oblanceolate-elliptic, marginally spreading (vs. coriaceous, broadly ovate to ovate-elliptic, marginally revolute in Phaeostemma fucata ), calyx lobes 5.5-6 mm long (vs. 8.5 mm long in Phaeostemma fucata ), staminal corona lobes (Cs) 3-3.2 mm wide, narrower at lateral extremes (vs. 2.3 mm wide at apex, somewhat obtuse at lateral extremes [projections] in Phaeostemma fucata ), and pollinia longer, 1-1.15 mm (vs. ca. 0.8 mm long in Phaeostemma fucata ).

Type.

SURINAME. Lely Mts., SW plateaus covered by ferrobauxite, in secondary vegetation, at end of airstrip, alt. 550-710 m, 1 Oct 1975, J.C. Lindeman, A.L. Stoffers, A.R.A. Górts-van Rijn & M.J. Jansen-Jacobs 654 (Holotype: U!; Isotype: MO!).

Description.

Vine, woody, slender. Stems densely pubescent, pubescence mixed eglandular and glandular trichomes, eglandular trichomes ubiquitous reddish-brown, stiff, usually spreading, multiseptate, 1.2-2.3 mm long, glandular trichomes spreading, scarce in mature stems, 0.2-0.3 mm long. Leaf blades membranous, narrowly elliptic to oblanceolate-elliptic, 10.2-15.0 × 3.8-5.8 cm (1.6-1.8 cm wide at base), apex short acute, base narrowly and shortly cordate, trichomes of surfaces, veins, and margins mixed, yellowish-red, adaxial surface strigose, eglandular multicelled trichomes antrorse, curved to subappressed 0.7-1.3 mm long, glandular trichomes 3-4-celled, spreading, 0.15-0.2 mm long, present mainly on midvein, abaxial surface hispid or hispidulous, eglandular multicelled trichomes erect, 0.25-0.7 mm long, glandular trichomes spreading on the midvein, 0.1-0.2 mm long, midvein adaxially sulcate, abaxially prominent, lateral veins in 6-7 pairs, slightly to strongly prominent; colleters 2, digitate-cylindric, 2.8-3.3 mm long; petioles 1.1-1.7 cm long, densely pubescent, pubescence ubiquitous, eglandular multicelled trichomes spreading, 2.8-3.3 mm long, glandular trichomes 3-4-celled, spreading, 0.1-0.2 mm long. Inflorescence racemiform, 2-4-flowered, 1(-2) flowers open at a time; peduncles 3-5 mm long, sparsely to moderately pubescent, pubescence ubiquitous, eglandular trichomes spreading, 1.2-2 mm long, glandular trichomes 3-4-celled, scarce, spreading, 0.2-0.3 mm long, rachis with scars, 3-4 mm long, bracts oblong, 1.8-2 mm long, abaxially pubescent, eglandular trichomes multicelled, 0.3-0.4 mm long, pedicels 24-33 mm long, densely pubescent, pubescence ubiquitous, eglandular trichomes spreading, 0.9-2.5 mm long, glandular trichomes 3-4-celled, spreading, 0.15-0.3 mm long. Calyx 8.5 mm long, lobes green, dark red at apex, oblong-elliptic, 5.5-6 × 2.4-2.6 mm, apex obtuse, margins entire, adaxial surface mostly glabrous, except few trichomes at apex, abaxial surface densely pubescent, eglandular multicelled trichomes spreading or antrorse, 0.9-1.5 mm long, glandular trichomes 2 -3-celled, spreading, 0.1-0.3 mm long, colleters 1 per sinus. Corolla pale green, with green vein network (fide collectoris), broadly subcampanulate, tube 5.5-5.8 mm long, up to 7 mm wide, sparsely short pubescent on the abaxial side, lobes imbricate in bud, deltoid, spreading, 8-9 × 9-10 mm, adaxial surface glabrous, abaxial surface densely pubescent, eglandular trichomes reddish-brown curved, antrorse, 0.5-1.5 mm long, glandular trichomes 3-4-celled, scarce, 0.15-0.25 mm long, apices obtuse-emarginate, margins entire. Gynostegium stipitate, style-head green yellow, somewhat concave, 4.3-4.5 mm in diameter, stipe 2.5 mm long, terminal style-head appendage absent. Corona gynostegial, fleshy, of 5 staminal (Cs) apically bifid segments fused to the corolla tube for most of its length, free in the upper 1.5-1.6 mm, apical area bifurcate, dorsally flattened, 3-3.2 mm wide at apex; anthers subtriangular, 1.9-2.1 mm wide between wings; nectar chambers ca. 2.5 × 2.6 mm. Pollinarium: corpuscula narrowly obovate-sagittate, ca. 0.5 × 0.33 mm long, caudicles ca. 0.22 mm long, pollinia triangular-pyriform, 1.0-1.15 × 0.6 mm. Follicles in very immature state, ca. 2 cm long, apparently 5-costate, densely glandular-pubescent, eglandular trichomes not seen, glandular trichomes 2-3-celled, 0.1-0.15 mm long. Seeds unknown.

Distribution and ecology.

Growing on a plateau covered with ferrobauxite rock. Endemic to Suriname, in tropical rain forests 500 to 710 m.

Phenology.

Collected in flower in October.

Conservation status.

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

Figures

Figure 3. Flower of Phaeostemma surinamensis. A Abaxial view showing calyx and abaxial corolla lobes B Side view showing adaxial corolla surface and gynostegial corona C Style-head D Staminal corona (Cs). Based on Lindeman et al. 654 (U).

Figure 6. Detail of flower (adaxial view) of Phaeostemma surinamensis from holotype (Lindeman et al. 654, U).