Xylopia tenuipetala D.M.Johnson & Goyder

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/137025003/137048402

Conservation

EN - endangered

Johnson DM et al. 2017. New species of Xylopia (Annonaceae) from East Africa. Kew Bulletin 72:11. DOI 10.1007/S12225-017-9681-X

Type

Type: Mozambique, Cabo Delgado Province: c. 1 km W of Quiterajo airstrip on track towards Namacubi Forest, Waypoint JT 627, 11°45'58.9"S, 40°23'59.8"E, 88 m, Goyder et al. 6090 (holotype K!; isotypes LMA! LMU! P!).

Morphology General Habit

Shrub or tree up to 5 m tall

Morphology Twigs

Twigs green to brownish grey, longitudinally wrinkled, with epidermis soon exfoliating, glabrous; nodes occasionally with two or more axillary branches

Morphology Leaves Leaf lamina

Lamina of larger leaves 4.6 – 5.7 cm long, 2.3 – 2.7 cm wide, chartaceous to subcoriaceous, concolourous, lanceolate to ovate, apex gradually acuminate with an acumen 4 – 11 mm long, base broadly cuneate to rounded, glabrous on both surfaces; midrib plane adaxially, raised abaxially; secondary veins 9 – 12 per side, diverging at 60 – 70° from the midrib, weakly brochidodromous; secondary and higher-order veins slightly raised on both surfaces; petiole 3.5 – 5 mm long, nearly terete to shallowly canaliculate adaxially, glabrous

Morphology Reproductive morphology Inflorescences

Inflorescences axillary, rarely pseudoterminal from abortion of the terminal bud, 1-flowered; peduncle rudimentary; pedicels 6.7 – 7.2 mm long, glabrous, bracts 2, clasping, the lower one proximal to the pedicel midpoint, 0.7 – 0.8 mm long, ovate, the upper one distal to the pedicel midpoint, 0.9 – 1.4 mm long, broadly ovate; buds lanceolate, apex acute

Morphology Reproductive morphology Flowers Calyx

Sepals 3=5- connate, 1.7 – 2.6 mm long, 2.1 – 2.5 mm wide, chartaceous, broadly ovate, apex acute, glabrous abaxially

Morphology Reproductive morphology Flowers Corolla

Petals yellow-green in vivo, membranous with venation evident; outer petals spreading at anthesis, 13 – 16 mm long, 2.9 – 3.4 mm wide at base, 1.6 – 1.9 mm wide at midpoint, lanceolate, flat, shallowly concave adaxially, apex acute, sparsely pubescent in the centre, becoming more densely pubescent toward margins adaxially, appressed-pubescent abaxially; inner petals erect at anthesis, 9.0 – 10.5 mm long, 1.8 – 2.1 mm wide at base, 1.2 – 1.7 mm wide at midpoint, linearlanceolate, apex acute, shallowly concave at base, glabrous

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens many, 1.2 – 1.5 mm long, narrowly oblong; apex of connective minute, not exceeding anther thecae, truncate; filament 0.5 – 0.7 mm long, forming c. ½ of stamen length; a few of the innermost stamens staminodial, 1 – 1.1 mm long, oblong, truncate; staminal cone 0.6 mm high, 0.8 mm in diam., irregularly laciniate

Morphology Reproductive morphology Flowers Gynoecium Carpels

Carpels 2 – 5; ovaries 1.1 – 1.5 mm long, narrowly oblong, glabrous; stigmas loosely appressed, 1.1 – 1.2 mm long, lanceolate-falcate, apex acute, glabrous; ovules at least 2 in a single row

Morphology Reproductive morphology Flowers

Torus 1mmin diam., glabrous

Morphology Reproductive morphology Flowers Pedicel

Pedicel of fruit with bracts and sepals persistent, 6.3 mm long, 1.3 mm thick, glabrous; torus of fruit 2.8 mm in diam., 1.5 mm high

Morphology Reproductive morphology Fruits

Monocarps red, dehiscing to reveal a red endocarp in vivo, 2 per fruit, 1.8 cm long, 0.9 cm wide, c. 0.5 cm thick oblong, flattened-ellipsoid in cross section, truncate and obliquely mucronate (1.5 mm) at the apex, based contracted into a stipe c. 4 mm long, 1.4 mm thick; pericarp 0.3 mm thick, finely verrucose, glabrous

Morphology Reproductive morphology Seeds

Seeds arranged in a single row, oriented perpendicular to long axis of monocarp, blue grey in vivo, becoming black and shiny when dry, 4 – 5 permonocarp, 7.1 – 7.9 mm long, 4.4 – 4.7 mm wide, 3.3 – 3.7 mm thick, oblong-ellipsoid, elliptic to oblong in cross section, smooth, rounded at chalazal end, obliquely truncate at micropylar end, raphe/antiraphe not evident on surface; micropylar scar 1.2 – 1.5 mm in diam., circular, flat; aril forming a cup over the end of the seed, 3.9 – 4.4 mm in diam., 2.0 – 2.4 mm high, white in vivo, amber-coloured when dried, fleshy

Distribution

Africa: northeastern Mozambique (Map 1).

Ecology

Dry coastal sand forest under Pteleopsis and Guibourtia schliebenii, understorey sometimes with species of Warneckea and Strychnos, at low elevation (65 – 134 m). This species shares a similar geographic distribution with a number of species occurring in the same dry forests: Micklethwaitia carvalhoi (Harms) G. P. Lewis & B. D. Schrire (canopy tree), Pyrostria sp. B of Flora Zambesiaca, Stylochaeton tortispathus Bognor & Haigh, Tarenna sp. 53 of Degreef, Thespesia mossambicensis (Exell & Hillc.) Fryxell, Tricalysia sp. B of Flora Zambesiaca, and Warneckea cordiformis R. D. Stone.

Conservation

The serious threats facing this narrowly endemic species are directly related to the same infrastructure development described for the previous species. All known locations are threatened by the expansion of the main road from Mocimboa to Palma. Again taking a grid cell as 3.17 km2 the AOO computes to 60 km2 and the EOO very nearly 158 km2. The IUCN conservation assessment for this species is EN B1ab(iii) + B2ab(iii).

Phenology

Flowers collected in November, fruits in December.

Note

This species also resembles Xylopia mwasumbii, known from several localities in northern coastal Tanzania (Johnson et al. 1999), but differs in the lanceolate to ovate leaves that are broadly cuneate to rounded at the base and acuminate at the apex, vs elliptic leaves that are narrowly cuneate and decurrent at the base and obtuse, emarginate, or blunt-acuminate at the apex, the longer (6.7 – 7.2 vs 2.5 – 4.6 mm long) pedicels, and the longer outer (13 – 16 vs 8 – 10 mm) and inner (9 – 10.5 vs 5.7 – 7.5) petals, and the glabrous ovaries. The petals of the new species are also unusual in the genus in being thin, membranous, and translucent rather than coriaceous or fleshy. Both species share, however, the dull flower colour and petal orientation, the short thick stigmas, and the cuplike aril present on the seed. X. tenuipetala may be distinguished from X. lukei, which it overlaps in distribution, by the smaller concolourous leaves, the longer pedicels (6.7 – 7.2 vs 4.5 – 6 mm) with smaller bracts (0.7 – 1.4 vs 2.5 – 2.9 mm), and the thinner petals. Xylopia tenuipetala belongs, together with X. lukei and X. mwasumbii, to an isolated but distinctive species group within the genus marked by a unique suite of characteristics including the reduced anther connectives, thick stigmas, and probably a cupular aril on the seed (seeds are not yet known from X. lukei). The group is restricted to the coastal forests from central Tanzania to northern Mozambique, where the species are mostly allopatric. The closest approach to sympatry is the northernmost locality for X. tenuipetala (Map 1). A similar biogeographic pattern occurs among eastern African species of Warneckea sect. Carnosae (Melastomataceae) (Stone 2013), in the genera Oxyanthus and Didymosalpinx (Rubiaceae) (Burrows & Burrows 2010), and perhaps within the eastern African clade of Monodora (Annonaceae) species (Couvreur 2009). Timberlake et al. (2011) discussed diversity and endemism in the coastal dry forests of northern Mozambique, but did not suggest whether local endemics there were relictual or of more recent origin. Comparative analysis of phylogenetic relationships within these groups might reveal consistent patterns between speciation and geographic location. Similar to Xylopia mwasumbii but differs in its lanceolate to ovate leaf laminas that are acuminate at the apex and broadly cuneate to rounded at the base (vs broadly elliptic to elliptic, blunt-acuminate, obtuse or emarginate at the apex and cuneate at the base and decurrent on the petiole in X. mwasumbii), pedicels 6.7 – 7.2 mm long (vs pedicels only 2.5 – 4.6 mm long) and outer petals 13 – 16 mm long and membranous in texture (vs 8 – 10 mm long and coriaceous or fleshy in texture). Verdcourt (1971) identified numerous eastern African Xylopia collections as the species X. parviflora (A. Rich.) Benth. That name has been rejected (Maas et al. 1986) and replaced by X. longipetala De Wild. & T. Durand. Close comparison of material identified as this taxon from across Africa has, however, shown that the specimens from western and central Africa, including the type of X. longipetala, differ consistently in numerous ways from the East African material: Leaf lamina rounded at the base; pedicels 6.2 – 12 mm long, bearing thin but persistent bracts; sepals reflexed at anthesis; petals thread-like, the outer petals 24 – 50 mm long and the inner petals glabrous adaxially; staminal cone usually longer than wide, with the ovaries exceeding the apex of the staminal cone; stigmas 4.5 – 7 mm long and falcate; monocarps longitudinally wrinkled/ribbed; sarcotesta of seed yellow-green to blue; plants of inland riparian habitats . . . Xylopia longipetala De Wild. & T. Durand Leaf lamina cuneate at the base; pedicels 3 – 5 mm long, bracts caducous; sepals erect at anthesis; petals linear but not thread-like, the outer petals 11.5 – 23.4 mm long and the inner petals densely puberulent adaxially; staminal cone wider than long, concealing the ovaries; stigmas up to 1.6 mm long, straight; monocarps obliquely wrinkled; sarcotesta of seed orange; plants of low-elevation coastal thicket. . . . . . . . Xylopia parviflora sensu Verdcourt 1 Xylopia parviflora sensu Verdcourt in fact shares more similarities with X. odoratissima Welw. ex Oliv. than with X. longipetala, and studies are underway to determine whether the two species are actually distinct. In reviewing the East African material we found, however, two groups of specimens that represent distinctive new species. The species epithet alludes to the translucent membranous dried petals.