Xylopia annoniflora Pombo & C.E.Zartman, 2017

Pombo, Maihyra M., Johnson, David M., Chatrou, Lars W. & Zartman, Charles E., 2017, Xylopia annoniflora (Annonaceae): a new species from central Amazonia, Phytotaxa 317 (2), pp. 130-136 : 131-135

Xylopia annoniflora Pombo & C.E.Zartman , sp. nov. ( Figs. 3 , 4 )

Type:— BRAZIL. Amazonas: Municipality Presidente Figueiredo, Balbina Village, Uatumã Biological Reserve, Fuzarca Island, 1°50’10.88”S 59°82’25.99”W, 78 m, 26 August 2015, Pombo et al. 667 (fl., fr.) (holotype: INPA).

The new species is similar to X. longicuspis Fries (1934: 210) and X. platypetala Fries (1934: 211) in its understory habit, hairy twig apices and leaf surfaces, oblong leaf blades reaching 17 cm in length, petals ca. 15 mm, but it differs from these two species in its oblique leaf base, sulcate venation on the adaxial leaf face, reduced pedicels (1–2 mm long), narrow sepals (4–8 mm wide) and pilose, falciform stigmas curved to the side.

Small trees, 2–5 m tall, DBH 3–5 cm, trunk cylindrical straight at the base, bark brown to rust-coloured with longitudinal fissures. Primary branches with scattered circular and elliptic lenticels yellow to light brown, simple trichomes golden to rust-coloured, 1–3 mm long, apical leaf buds velutinous. Cataphylls present at or near branch apices associated with new leaves, 3–5 cm long, triangular with simple adpressed trichomes covering their surface. Leaves simple, alternate, distichous; petiole 1–10 × 2–4 mm long, velutinous and deciduous, adaxially furrowed with a dilated base; leaf lamina 17.0–29.0 × 3.7–8.6 cm, elliptical to oblong, apex acuminate (5–10 mm), base rounded and oblique, margins entire and plane, adaxial side with sparse simple hairs, bright green; abaxial side with scattered, whitish glands due to a thin cuticle layer, velutinous with rust-coloured trichomes, principal and secondary veins impressed and sulcate on the adaxial side and prominent on the abaxial side; venation brochidrodomous and reticulate, 8–17 pairs of secondary veins, with an angle of (30°) 40°–50° (60°) from the midrib. Flowers solitary, subsessile, axillary; pedicels 1–2 mm long, velutinous, with 1–2 triangular, brown bracts, 7 × 4 mm. Floral buds round, trilobed and covered with golden adpressed simple trichomes; sepals triangular 12–14 × 4–8 mm, green in vivo, connate at the base, velutinous and covered externally with golden trichomes. Petals white in vivo, outer petals ovate 21–28 × 2–7 mm at the base and 15–16 mm at midpoint, apex rounded, slightly concave and externally velutinuous, golden, adpressed, simple trichomes covering the surface, inner petals elliptic, 15–26 × 1–3 mm at the base and 9–12 mm at midpoint, apex acute, concave and externally velutinous. Stamens 200–250, fertile stamens ca. 3 mm long, spatulate, apex of connectives 1–2 mm long, capitate, papillate, anthers with 8–10 locelli, filaments 1–2 mm long, staminodes, 25–30, ca. 3 mm long, clavate and flattened, outer staminodes ca. 3 mm long, clavate, flattened, apex of connective 1–2 mm long, capitate, papillate, inner staminodes ca. 3 mm long, clavate, flattened, apex of connective 1–2 mm long, capitate, papillate; staminal cone 8–10 mm in diameter, 2–3 mm long. Carpels ca. 20–21, 7–12 mm long, ovary 1–3 mm long, lanceolate, densely velutinous, styles 1–3 mm long, stigma falciform, with simple trichomes, 5–6 mm long. Unilocular ovary, 1–2 ovules in each locule, Placentation parietal. Fruit with ca. 21 claviform, rounded-apiculate monocarps, 2.0–3.0 × 0.9–1.8 cm, whitish-green sparsely covered with golden erect simple trichomes; monocarp stipe 1–2 mm long, 1–2 seeds, black, oblong, oblique on the monocarp axis, 12–15 × 5–6 mm, entire aril white, apical and bilobed, 4 × 2 × 2 mm.

Other specimens examined:— BRAZIL. Amazonas: island in the Uatumã River, Balbina Dam , 06 August 2006, Zartman et al. 5900 ( INPA 227116 ) ; island in the Uatumã River, Balbina Dam , August and October 2015, Pombo et al. 663, 711, 721 ( INPA) .

Etymology:— Xylopia annoniflora refers to the unusually large flowers for Xylopia and similarity to those of many Annona species.

Distribution and Habitat:— Specimens from five individuals of X. annoniflora were collected from two islands in the Biological Reserve of Uatumã located in the municipality of President Figueiredo, Amazonas, Brazil. These are remnants of hilltops for which the surrounding areas were flooded by construction of the Balbina Dam in 1985. The site of the holotype collection is characterised by clay-based soils in dense ombrophilous forest dominated by canopy trees such as Goupia glabra Aublet (1775: 296) , Goupiaceae , and Palma maripa Aublet (1775: 974) , Arecaceae , among others.

Phenology:— Flowers and fruits were observed in August 2015.

Notes:— Morphologically, species most similar to X. annoniflora are X. longicuspis and X. platypetala because they both have large leaves with conspicuously reticulate venation. However, the new species differs from them based on the characters described above in diagnosis. Perhaps the most strikingly distinctive features of X. annoniflora are in its flower morphology: strongly concave-rounded petals and falciform, pilose stigmas.

Xylopia longicuspis is a shrub without lenticels on primary branches, and X. annoniflora is a tree of ca. 5 m height with numerous lenticels. Floral characteristics also distinguish the two species as X. longicuspis is cauliflorous with pedicels reaching 1 cm in length and glabrous stigmas ( Fries 1934), whereas X. annoniflora produces subsessile flowers on leafy branches (cauliflory was not observed) with pilose, falciform stigmas. In X. platypetala , the pedicel is evident (ca. 5 mm long), whereas flowers of X. annoniflora are subsessile with pedicles rarely reaching 2 mm. Furthermore, X. platypetala flower buds are smaller (<1 cm in diameter) than those of X. annoniflora (2.0– 2.5 cm).

Petal structure is subtly different among these three species. In the outer whorl, petals gradually narrow toward an acute apex in X. longicuspis , in X. platypetala they are broadly ovate, flat, moderately long-acute ( Fries 1934) and in X. annoniflora they are rounded-ovate with sub-acute apices. Inner petal whorls of X. longicuspis are narrowly triangular, those of X. platypetala are lanceolate and they are elliptic in X. annoniflora . Information available on X. longicuspis and X. platypetala is nearly entirely restricted to their original descriptions, and fruit and seed characters remain unknown for these taxa.

During collection of the holotype, large scarab beetles were observed inside the flower ( Fig. 4E ). According to Saunders (2012), Xylopia flowers are preferably visited by small beetles and thrips. Observations on the pollination biology of Amazonian species of Xylopia are scarce and need to be expanded.

Figures

FIGURE 3. Illustrations of Xylopia annoniflora. A. Leaves on branch. B. Cataphylls at branch apex. C. Flower bud. D. Flower. E. Stigma. F. Fruits and seed. Illustration by C.E. Zartman.

FIGURE 4. Details of Xylopia annoniflora. A. Adaxial and abaxial leaf faces. B. Cataphylls at branch apex. C. Flower detail (external). D. Flower detail (internal). E. Scarab beetles inside the pollination chamber. F. Fruit. Photographs by M.M. Pombo.