Xylopia humbertii Ghesq. ex Cavaco & Keraudren, 1957

Johnson, David M. & Murray, Nancy A., 2020, A revision of Xylopia L. (Annonaceae): the species of Madagascar and the Mascarene islands, Adansonia 42 (1), pp. 1-88 : 64-65

publication ID

http://doi.org/ 10.5252/adansonia2020v42a1

persistent identifier

http://treatment.plazi.org/id/417D87A4-FFBC-FFAE-FF42-550C3215F9AD

treatment provided by

Tatiana

scientific name

Xylopia humbertii Ghesq. ex Cavaco & Keraudren
status

 

23. Xylopia humbertii Ghesq. ex Cavaco & Keraudren   ( Fig. 21L-O View FIG )

Bulletin du Jardin botanique de l’État à Bruxelles 27: 87 (1957). — Type: Madagascar. Prov. Mahajanga [“Centre”], entre Mandritsara et Andilamena, 900-1200 m, XI.1937 (fl.), Humbert 17980 (holo-, P[P030395]!;   iso-, P[P030396, P030397, one without bar code]!)   .

DISTRIBUTION, ECOLOGY AND CONSERVATION STATUS. — Xylopia humbertii   is known only from its type, which was collected in eastcentral Madagascar at an elevation of 900-1200 m with flowers in early November ( Fig. 29 View FIG ).The habitat is described as forest remains and secondary growth (savoka) of the eastern slope, on lateritic soil derived from gneiss. The type locality appears to fall within the boundaries of Marotandrano National Park. The species has not been re-collected since 1937 and should be regarded as of high conservation concern; it is given a preliminary conservation assessment of Critically Endangered ( Table 2 View TABLE ).

DESCRIPTION

Small tree.

Twigs glabrous or with a few scattered appressed hairs, the hairs 0.1-0.2 mm long, but soon glabrate; nodes with one axillary branch.

Leaves with larger blades 5.2-6.3 cm long, 2.2-2.8 cm wide, subcoriaceous to coriaceous and somewhat conduplicate, discolorous, shiny and olive gray to blue gray adaxially, dull and light brown abaxially, elliptic, apex acute to blunt-acuminate, the acumen 3-5 mm long, base cuneate and decurrent on petiole, margin slightly recurved, glabrous on both surfaces, rarely with a few scattered hairs abaxially; midrib concolorous with blade or dark red toward base adaxially, secondary veins weakly brochidodromous, 11-12 per side, diverging at 70-80° from midrib, slightly raised adaxially, raised abaxially, higher-order veins indistinct adaxially, raised abaxially; petiole 4-5 mm long, semi-terete, faintly wrinkled, glabrate or with a few hairs.

Inflorescences axillary, 1-flowered, not pedunculate, pubescent; pedicels strongly recurved, 3.8-4.3 mm long, 0.9-1.1 mm thick; bracts 2, both attached proximal to pedicel midpoint, caducous, c. 0.5 mm long, semicircular; buds lanceolate, apex obtuse.

Sepals spreading at anthesis, 1/3-connate, 1.9-3.0 mm long, 2.5-3.0 mm wide, coriaceous, semicircular, apex acute, pubescent abaxially.

Petals white in vivo; outer petal position at anthesis unknown, 12.6-14.6 mm long, 3.1-3.7 mm wide at base, 2.1-2.5 mm wide at midpoint, coriaceous to fleshy, lanceolate, with a faint ridge at apex adaxially, faintly ridged abaxially, apex obtuse, shallowly concave adaxially, densely puberulent except for glabrous base adaxially, densely pubescent except for a glabrous patch at base abaxially; inner petals with position at anthesis unknown, 10.6-12.3 mm long, 2.7-3.1 mm wide at base, 1.1-1.4 mm wide at midpoint, coriaceous, linear-lanceolate, keeled on apical ¼-1/3 adaxially, keeled abaxially, apex acute, base concave with undifferentiated margin, densely puberulent at apex and along margins adaxially, puberulent except for glabrous base abaxially.

Stamens c. 80; fertile stamens 1.5-1.9 mm long, narrowly oblong, anther connective apex 0.4-0.5 mm long, capitate, overhanging the anther thecae, papillate, anthers 9-13-locellate, filament 0.4-0.7 mm long; outer staminodes absent; inner staminodes 1.0- 1.4 mm long, oblong, apex truncate to obtuse; staminal cone 1.4-2.0 mm in diameter, 0.6-1.3 mm high, concealing all but apices of the ovaries, rim irregularly laciniate.

Carpels 5-6; ovaries c. 1.1 mm long, oblong, pubescent, stigmas loosely connivent, 2.9-3.2 mm long, falciform-lanceolate, pilose at apices.

Fruits and seeds unknown.

NOTES

The combination of glabrate subcoriaceous leaves and relatively short broad buds and outer petals distinguishes X. humbertii   from other Madagascar species. It most closely resembles X. perrieri   , another species from higher elevations, but the latter has densely appressed-pubescent lower leaf surfaces and longer pedicels. The twigs in X. humbertii   are initially reddish brown with the epidermis soon exfoliating, and densely marked with protuberant white lenticels.

Two specimens from the Montagne d’Ambre region of extreme northern Madagascar, Capuron 20051 SF [P01986981] and Ursch 245 [P01986961], resemble X. humbertii   in the tendency for the subcoriaceous leaves to be conduplicate and thus longitudinally folded when pressed. These specimens may represent a distinct species, differing from the type material of X. humbertii   in the more densely pubescent young twigs, the slightly larger leaves, and the more acute angle of the secondary veins (45-50°). Capuron 20051 SF has, in addition to immature fruits, an old flower receptacle, which shows the sepals c. 4.3 mm wide, i.e. wider than in the type material of X. humbertii   . The specimen Ursch 245, annotated by Ghesquière as Xylopia danguyella Ghesq.   in 1938 and identified as that species by Cavaco & Keraudren (1958), bears nearly mature monocarps, which are 3.9-4.9 cm long, c. 1.7 cm wide, and 1.5-1.6 cm thick, oblong, with a short broad beak 2.5-4.5 mm long and a short stipe 8-9.5 mm long and 4-5 mm thick. The monocarps are obliquely wrinkled, strongly verrucose between the wrinkles, and contain up to 8 seeds arranged in a single row. This monocarp morphology is different from that of X. danguyella   , but similar to that of Capuron 20051 SF.

Kingdom

Plantae

Phylum

Tracheophyta

Class

Magnoliopsida

Order

Magnoliales

Family

Annonaceae

Genus

Xylopia

Loc

Xylopia humbertii Ghesq. ex Cavaco & Keraudren

Johnson, David M. & Murray, Nancy A. 2020
2020
Loc

Xylopia humbertii

Xylopia humbertii Ghesq. ex Cavaco & Keraudren ( Fig. 21L-O ) Bulletin du Jardin botanique de l’État à Bruxelles 27: 87 (1957). — Type: Madagascar . Prov. Mahajanga [“Centre”], entre Mandritsara et Andilamena, 900-1200 m, XI.1937 (fl.), Humbert 17980 (holo-, P[P030395]!; iso-, P[P030396, P030397, one without bar code]!) .