Leoheo domatiophorus Chaowasku, D.T. Ngo & H.T. Le,, 2018

Chaowasku, Tanawat, Damthongdee, Anissara, Jongsook, Hathaichanok, Ngo, Dung T., Le, Hung T., Tran, Duc M. & Suddee, Somran, 2018, Enlarging the monotypic Monocarpieae (Annonaceae, Malmeoideae): recognition of a second genus from Vietnam informed by morphology and molecular phylogenetics, Candollea 73 (2), pp. 261-275 : 268-271

Leoheo domatiophorus Chaowasku, D.T. Ngo & H.T. Le, spec. nova

( Fig. 2C–H, 3A, 4A, 5–7 ).

Holotypus: VIETNAM. Prov. Thua Thien-Hue: Nam Đông Distr ., 19.III.2009, fl., HUAF collectors 2009-0 3-19 -ND ( CMUB!; iso-: G!, P!).

Leoheo domatiophorus Chaowasku, D.T. Ngo ð H.T. Le differs from species of the genus Monocarpia Miq. by the lack of intramarginal leaf veins and by having axillary inflorescences, leaf domatia, longitudinal ridges on the monocarp surface, and subsessile monocarps with a stout stipe.

Medium-sized (to large) trees, 15–25(–30) m tall; young twigs puberulous with appressed hairs. Petiole 5 – 8 mm long, grooved on upper surface, both sides puberulous with appressed hairs; leaf blade elliptic, 9.1– 22.8 × 3.1– 6.5 cm, both surfaces glabrous, base cuneate, apex caudate-acuminate; midrib raised and puberulous with appressed hairs on lower surface, sunken (becoming less so toward apex) and puberulous with appressed and erect hairs (more sparsely so toward apex) on upper surface; secondary veins 11–12 per side, angle with midrib at middle part of leaf blade 40°– 50°. Flower(s) in a 1- to 2-flowered axillary inflorescence, bisexual; peduncle 7–10 mm long (up to 17 mm long and 6–8 mm thick in fruit), indumentum puberulous-tomentose with erect hairs, bract(s) often leaf-like, placed at top of peduncle, often caducous; pedicel 2–2.5 cm long (6–7 mm thick in fruit), tomentose with erect hairs, bracts ovate, generally 2 per pedicel, one placed at ± midpoint of pedicel, another near pedicel base, often caducous. Sepals triangular-ovate, 8–11 × 7–8 mm, both surfaces and margin tomentose with erect hairs. Outer petals obovate, 5.8–6.2 × 1.8–2.1 cm, both surfaces and margin puberuloustomentose with erect hairs, apex obtuse-rounded; inner petals elliptic-obovate, 5.9–6.1 × 2–2.3 cm, indumentum similar to that of outer petals, apex obtuse. Torus volcano-shaped with a slightly sunken apex, glabrous. Stamens 70–76 per flower, c. 2 mm long, connective truncate, covering thecae. Carpels 3–4 per flower, 4.5–6 mm long; stigmas ± peltate and irregularly lobed (5–6 lobes); ovaries villous with appressed hairs; ovules 15–17 per ovary, lateral, biseriate. Monocarp(s) 1– 4 per fruit, subsessile (with a stout stipe), cylindrical, 5.5–7.5 × 3–3.5 cm, pericarp c. 3 mm thick, hardened when dry, surface shallowly coarsely rugose-verrucose with 7–8 longitudinal ridges (some ridges running to only midpoint of monocarps, whereas some forming loops with others), indumentum short-tomentose (often more sparsely so or almost glabrous on ridges), apex not apiculate. Seeds 9–17 per monocarp, flattened-ellipsoid to flattened-ovoid, 1.7–2.1 × 1– 1.2 cm, more flattened for in-between seeds, surface pitted and slightly rugose, raphe slightly raised with a slight groove in the middle, endosperm ruminations spiniform.

Etymology. – The specific epithet domatiophorus is a masculine adjective in first and second declensions, referring to “domatia” on the lower leaf surface.

Habitat and phenology. – Occurring in (edges of) evergreen forests, disturbed evergreen forests, or edges of secondarforests adjacent to the primary ones; on a steep hillside or near a stream at 270–350 m. Flowering material collected in March. Fruiting material collected in July.

Conservation status. – Leoheo domatiophorus grows in lowland rainforests of Nam Đông (where part of Bach Ma National Park is located) and A Luoi Districts of Thua Thien-Hue Province ( Fig. 7 ), and has also been observed in the adjacent Quang Tri and Quang Nam Provinces as well. This habitat has been continuously destroyed for Acacia Mill. cultivation and other kinds of deforesting land use. Furthermore, only a small part of the habitat of L. domatiophorus is protected in the Bach Ma National Park. Due to its restricted range in threatened lowland rainforests of central Vietnam, the new species qualifies as “Vulnerable” [VU B2ab(iii)] using the IUCN Red List Categories and Criteria ( IUCN, 2012).

Paratypi. – VIETNAM. Prov. Thua Thien-Hue: Nam Đông Distr., 16°08'N 107°37'E, VII.2014, ster., Chaowasku 129 (CMUB); A Luoi Distr., 16°01'N 107°31'E, VII.2014, ster., Chaowasku 130 (CMUB); ibid. loco, VII.2014, fr., Chaowasku 131 (CMUB); Nam Đông Distr., 16°08'N 107°37'E, VII.2016, fr., Chaowasku 165 (CMUB); ibid. loco, VII.2016, ster., Chaowasku 166 (CMUB).

Figures

Fig. 1. – 50% majority-rule consensus phylogram derived from Bayesian inference of combined seven plastid DNA regions. Bayesian posterior probabilities (PP) indicated on the right; maximum likelihood bootstrap (BS) percentages in the middle; parsimony symmetric resampling (SR) percentages on the left [** denotes BS/SR <50%]. DEN. = Dendrokingstonieae; MAL. = Malmeeae; MIL. = Miliuseae; MON. = Monocarpieae; PIP. = Piptostigmateae. Scale bar unit = substitutions per site.