Trigynaea flagelliflora Lobão, 2017

Lobão, Adriana Quintella, 2017, A new species of Trigynaea (Annonaceae) endemic to the Atlantic Forest of Brazil, Phytotaxa 309 (2), pp. 193-196 : 193-195

Trigynaea flagelliflora Lobão , spec. nov. ( Fig. 1 )

Type:— BRAZIL. Espírito Santo: Cachoeiro de Itapemirim, RPPN Cafundó, trilha entre as parcelas 14 e 20 , 20°71’33”S 41°22’17”W, 16 March 2013 (fl, fr), Zorzanelli et al. 10 (holotype RB!; isotype VIES!) .

Trigynaea flagelliflora is unique among species of Trigynaea due to the flowers born on flagelliform inflorescences.

Tree c. 8.0 m tall. Young branches densely covered with appressed short, straight hairs, soon glabrous; leaves with canaliculate petiole, 2.0–5.0 mm long, 1.0– 1.5 mm in diameter, densely covered with appressed short straight hairs; blade narrowly elliptic or oblanceolate, 10.0–21.5 × 3.0– 6.3 cm, abaxial surface densely verrucose, grayish green when dry, both sides glabrous, base rounded, asymmetrical, margin flat, apex acute; venation brochidodromous; primary vein canaliculate on adaxial surface, raised on abaxial surface, secondary veins distinct, 12–14 on either sides of primary vein, smallest distance between loops and margin 1.0–3.0 mm, angles with primary vein c. 40°, tertiary veins reticulate, secondary and higher-order veins slightly raised on both sides. Inflorescence arising from the main trunk, at least 2.2 m long, 1.0–2.0 mm in diam.; pedicels 1.0– 2.3 mm long, 0.5–1.0 mm in diam., densely covered with appressed short straight hairs; flower buds widely ovoid, 0.6–1.2 mm long, dark green, covered with appressed short curly hairs; sepals broadly triangular, c. 2.0 × 2.0 mm, adaxial surface smooth and glabrous, abaxial surface papillose and covered with appressed curly hairs; outer and inner petals ovate, apex acute, adaxial surface glabrous, abaxial surface papillose and densely covered with appressed curly hairs, outer petals 10.0–14.0 × 5.0–6.0 mm, abaxial surface green, adaxial surface white to yellowish, inner petals 12.0–14.0 × 6.0– 7.0 mm, both sides white to yellowish, abaxial surface keeled, keel densely covered with appressed straight hairs, stamens 50–60, c. 3.0 mm long, narrowly oblong, glabrous, anthers c. 2.0 mm long, apex of connective not expanded above the anther locule, filament c. 1.0 mm long; carpels 4; ovaries c. 3.0 mm long, oblong; somewhat 3–ribbed longitudinally, covered with appressed long straight golden-brown hairs; ovules 12–13, in two rows; stigmas c. 1.0 mm long, broadly funnel-shaped, not obviously bilobed; torus conical, 1.0–2.0 mm in diam., glabrous on staminate portion, covered with straight long hairs on carpellate portion. Fruit with 1 monocarp, sessile, monocarps dolabriform, c. 3.5 cm long, c. 2.0 cm in diam., mature glabrous, young densely covered with appressed straight hairs, shining green.

Distribution, habitat and phenology:— This species occurs in the Atlantic Forest of Espírito Santo in floresta estacional semidecidual submontana (forest type in which at least 50% of the species lose their leaves in the dry season). The area of the reserve is 517 ha, with an elevation of 400–640 metres. The species is restricted to the reserve, and c. 10 individuals have been observed. Flowering and fruiting is in March.

Etymology:— The specific epithet refers to the flowers on the long, flexible inflorescence.

Notes:— The flagelliform inflorescence of this species, unique in Trigynaea , develops on the base of the main trunk and grows horizontally on the forest floor reaching up to 2m in length. The inflorescence snakes through the leaf litter, and the flowers seem to borne directly on the ground.

Flagelliform inflorescence in Annonaceae , according to their origin, can be sympodial branches consisting of successive lateral shoots each terminating in a rhipidium or runners formed by elongation of a single rhipidium (Maas et al. 2003, Schatz & Wendt 2004). As the species of Trigynaea have no bracts and T. flagelliflora has leaves on the inflorescence, flagelliflory is probably a sympodial branch as in Hornschuschia bryotrophe , Duguetia flagellaris , D. sessilis and Stenanona flagelliflora .

Another unusual feature of T. flagelliflora is the verrucose leaves (more obvious in dry leaves), which until now, only T. triplinervis Johnson & Murray (1995: 283) has exhibited. The latter differs in its solitary flower on leafy shoots.

Among the Atlantic Forest species, T. flagelliflora is morphologically similar to T. oblongifolia and T. axilliflora based on the size and form of the leaves but can be differentiated from these two species by its verrucouse leaves, abaxial surface petals green and the flagelliform inflorescence.

Within Bocageeae , Trigynaea is similar to Hornschuchia and Bocagea in the flowers with small perianth and a few as six (rarely three) stamens and a single carpel. The three genera form a clade, and Trigynaea is sister to Hornschuchia + Bocagea ( Johnson & Murray 1995) . Reduction of stamen number separates Hornschuchia + Bocagea from Trigynaea . Although Trigynaea and Hornschuchia have no synapomorphies, they share connate sepals and carunculate seeds ( Johnson & Murray 1995). Hornschuchia , with ten species restricted to Atlantic Forest of eastern and southeastern Brazil, has different types of cauliflory, trunciflory ( H. cauliflora Maas & Setten, Maas et al. 1988: 259 ), idiocladanthy ( H. leptandra Johnson, Johnson & Murray 1995: 310 ) and flagelliflory ( H. bryotrophe Nees von Esenbeck, 1821: 302 ) ( Schatz & Wendt 2004). Trigynaea flagelliflora is similar to H. bryotrophe in the flagelliform inflorescence combined with the large brochidodromous leaves. It differs from that species by the features that distinguish Trigynaea from Hornschuchia : ovate petals, distinctly trilobed calyx and ovoid flower buds.

Figures

FIGURE 1. Trigynaea flagelliflora. A. Leafy branch. B. Flagelliform inflorescence. C. Flower bud. D. Open flower showing stamens and stigmas. E. Abaxial surface of the young outer petal. F.Adaxial surface of the young outer petal. G. Carpel. H. Stamens, lateral and frontal view. I. Monocarp.A–I from Zorzanelli 10 (RB, VIES).