Popowia bachmaensis (Annonaceae), a new species from Bach Ma National Park, Central Vietnam

Keywords: Annonaceae, Bach Ma National Park, new species, Popowia, Vietnam

Introduction

Popowia Endlicher is a small genus of the family Annonaceae. It was firstly described in the Genera Plantarum secundum Ordines Naturales for the type species, Popowia pisocarpa (Blume) Endl. ex Walp (Endlicher 1839). The species is a shrub or a small tree, characterized mainly by its (sub)granular leaves with asymmetric base, inner petals being larger than outer ones, apically broadly flat-topped to slightly concave stamen connectives, 1 or 2(–4) ovule(s) per carpel (Moeljono 2009; Li and Gilbert 2011). The genus comprises approximately 50–90 species, but many of these could in fact belong to other genera (Sinclair 1955). The majority are distributed in tropical Africa, and also recorded from Madagascar, India, Myanmar, Thailand, Malaysia, Vietnam, China, Indonesia, Philippines, and Papua New Guinea to Australia. (Sinclair 1955; Moeljono 2009; Li and Gilbert 2011).

The genus Popowia has been classified within tribe Mitrephoreae Hook. f. & Thomson with the genus Goniothalamus (Blume) Hook.f. & Thomson, Mitrephora Hook.f. & Thomson, Neouvaria Airy Shaw, Oxymitra Hook. f. & Thomson and Pseuduvaria Miq. (Sinclair 1955; Moeljono 2009). Recent molecular analyses suggested its placement under tribe Miliuseae including a total of 25 genera and ca. 510 species and also strongly supports its monophyly with Polyalthia s. str. as a sister clade (Chatrou et al. 2012; Xue et al. 2012; Mols and Keβler 2013; Chaowasku et al. 2014). The species of Popowia and Polyalthia s. str. are usually characterized by the asymmetrical leaf base, but they are differentiated in the patterns of secondary leaf venation (eucamptodromous in Popowia vs. brochidodromous in Polyalthia s. str.), and the number of ovules per carpel [1 or 2(–4) vs. 2–6] (Xue et al. 2012).

In a recent taxonomic revision of Annonaceae in Vietnam, Bân (2000) reported three species with one variety of Popowia: P. cambodica Finet & Gagnep., P. cambodica var. canaensis Bân, P. helferi Hook.f. & Thomson and P. pisocarpa. However, specimens of “P. cambodica and P. cambodica var. canaensis” identified by Bân (2000) are identical with Polyalthia debilis (Pierre) Finet & Gagnep (digitalized specimen images examined). As for “P. helferi”, the description by Bân (2000) does not match with the original description by Hook and Thomson (1872). Therefore, only P. pisocarpa can be considered as a reliable record in Vietnam.

Here, the second Vietnamese species of Popowia is reported, which was found in Bach Ma National Park, Phu Loc District, Thua Thien Hue Province. This national park was established in 1991 with a total area of 37,487 hectares and is recognized as a biodiversity hotspot because of its unique topography, high species richness and highly threatened biodiversity. The peak of Bach Ma Mt. is 1,450 m high and is covered by clouds almost throughout the year. The park preserves virgin forests, which depending on their altitudinal distribution can be classified as follows: seasonal evergreen forests, hill evergreen forests, and lower montane forests. So far 2,373 species of vascular plants, accounting for approximately 17% species of the total flora of Vietnam, have been recorded from the National Park (Bach Ma National Park 2016).

During our botanical inventory of Bach Ma National Park in 2015, a new species of genus Popowia was discovered, P. bachmaensis Ngoc, Tagane & Yahara, sp. nov. Here, it is described, illustrated and the DNA barcodes are provided of the two plastid regions rbcL and matK (CBOL Plant Working Group 2009) of the new species.

Popowia bachmaensis Ngoc, Tagane & Yahara, sp. nov.

Figure 1. Popowia bachmaensis, sp. nov.
a Holotype (KYO) b habit c flower d pedicel and sepals e sepals f section of flower g inner petal h fruit on branch i dried fruit j seed k carpel l, m stamens. Materials from Yahara et al. V2557 (KYO). Scale bars: d–g, i–m =1 mm.

Figure 2. Illustration of Popowia bachmaensis, sp. nov.
a Leafy twig b Flower c Pedicel and sepals d Fruit e Inner petal f Carpel and g Stamen. Materials all from Yahara et al. V2557 (FU). Drawn by Ngoc & Binh.

Type
VIETNAM. Thua Thien Hue Province, Bach Ma National Park, in evergreen forest, 16°13'41.60"N, 107°51'09.35"E (DMS), alt. 485 m, 23 May 2015, with flowers and young fruits, Yahara T, Tagane S., Toyama H., Nguyen Ngoc, Nguyen Chinh, Okabe N. V2557 (holotype: KYO!; isotypes: BKF!, DLU!, FU!, the herbarium of Bach Ma National Park!).