Aspidistra xuansonensis N.Vislobokov var. violiflora N.Vislobokov, 2014

Vislobokov, Nikolay A., Sokoloff, Dmitry D., Degtjareva, Galina V., Valiejo- Roman, Carmen M. & Kuznetsov, Andrey N., 2014, Aspidistra xuansonensis (Asparagaceae), a new species from northern Vietnam, Phytotaxa 173 (3), pp. 226-234 : 229-232

Aspidistra xuansonensis N.Vislobokov var. violiflora N.Vislobokov , var. nov. ( Fig. 1b, e )

Petiole 18.5–32 [24.9] cm long; blade to petiole length ratio 0.7-1.1 [1,1]; peduncle purple spotted; perianth lobes purple spotted to continuous purple at both sides; style purple; stigma purple at lower and lateral sides.

Type:— VIETNAM, Phu Tho province, Thanh Son district, Xuan Son National Park, 21˚ 07.164’ N, 104˚ 56.875’ E, alt. 555 m, rainforest, 2 Nov 2013, N. A. Vislobokov 13094 (holotype, MW! isotype, MW!), including flowers and fruits in liquid collection at Moscow University. Living plant derived from the same specimen as the isotype is in cultivation ( N. A. Vislobokov XS13AX02).

Molecular description:— Two newly investigated accessions corresponding to the two varieties of A. xuansonensis are identical in sequences of psb A- trn H and 5S-NTS regions. No sequence variation within accessions was found. Differences found in alignments of all currently available accessions of Aspidistra [ A. phanluongii Vislobokov in Vislobokov et al. (2013: 349); A. paucitepala Vislobokov et al. (2014: 272) ; Aspidistra sp. 1 ] of the two investigated markers in Aspidistra are summarized in Tables 1 and 2. In psb A- trn H region ( Table 1), the new species is similar to Aspidistra sp. 1 , an unidentified species collected without flowers in Lam Dong province of Vietnam (see Vislobokov et al., 2014). In 5 S- NTS region, the most remarkable features of the new species are a large fragment of unalignable DNA represented by nucleotides 52–177 (direct nucleotide positions; these are equivalent to positions 59–183 in the alignment, Table 2), a 126 bp indel between nucleotides 263 and 264 (direct nucleotide positions; these are equivalent to positions 437–562 in the alignment, Table 2) and a 44 bp indel between nucleotides 314 and 315 (direct nucleotide positions; these are equivalent to positions 614–657 in the alignment, Table 2). In addition, the following features distinguish 5S-NTS sequences of the new species from other accessions (in all cases, direct nucleotide positions): a 3 bp indesertion between nucleotides 7 and 11; Cytosine not Thymine or Guanine at position 12; Cytosine not Thymine at position 25; Guanine not Cytosine at position 196; Guanine not Thymine at position 207; Guanine not Adenine at position 241; Guanine not Cytosine at position 258; Cytosine not Guanine at position 262; Adenine not Thymine at position 265; Guanine not Adenine at position 268; Cytosine not Adenine at position 290; Adenine not Guanine at position 299.

Etymology:— The specific epithet “ xuansonensis ” is derived from the name of Xuan Son National Park, which is the type locality of the species.

Distribution and ecology:— The species is common in the type localities (Xuan Son National Park, Phu Tho province) near Lap and Du villages at elevation 350– 450 m. Aspidistra xuansonensis var. xuansonensis grows on medium loamy yellow ferrallitic soil on shale on mountain slopes under the canopy of long-boled tropical forest, as well as in a valley on medium loamy dark-colored soil between limestone hills in a forest. Aspidistra xuansonensis var. violiflora was found at 550 m in similar conditions as A. xuansonensis var. xuansonensis on mountain slopes.

A

Shoot system: —Rhizome of A. xuansonensis ( Fig. 3a ) consists of regularly repeating units (elementary shoots — Gatsuk 1974; Mikhalevskaya 2008), each unit comprising 7–12 distichously arranged cataphylls followed by a foliage leaf. Foliage leaves of at least three (sometimes four) successive elementary shoots are present simultaneously on a given plant. Emerging of new foliage leaves is asynchronous in different plants. Cataphylls enclose and protect a young foliage leaf and usually disintegrate and abscise when the leaf is fully emerged. Both cataphylls and foliage leaves have wide bases. Cataphylls are represented by open sheaths whose left and right margins overlap each other except near the sheath base. Pattern of this overlapping makes the rhizome dorsiventral, as the physically lower margin (i.e., the closer to the substrate) is the outer one. The sheathing base is extremely short in the foliage leaves, and its margins do not overlap. Foliage leaves also contribute to the dorsiventrality of the rhizome, as their petioles are displaced towards the physically upper side of the creeping shoot. Each cataphyll has an axillary bud with an adaxial two-keeled prophyll. In our material collected in November, some buds remain dormant. These contain ca. three young leaves completely enclosed within the hood-shaped prophyll. Other axillary buds develop specialized reproductive shoots (peduncles, Fig. 3b ). Their arrangement along two sides of the rhizome follows the distichous arrangement of the cataphylls; one ( Fig. 3 ) to seven ( Fig. 2g, h ) peduncles develop on either side of a rhizome. Typically, when peduncles with anthetic flowers are present in axils of cataphylls on of a given elementary shoot, fruiting peduncles can be seen in axils of cataphylls of the previous elementary shoot and very young flowers can be found within a bud of the subsequent elementary shoot.

Scaly leaves on the peduncles could be called hypsophylls (e.g., Weberling 1989), though in the absence of foliage leaves on these specialized shoots the difference between cataphylls and hypsophylls is problematic. The hypsophylls have wide bases (though the base is sometimes narrower in the uppermost hypsophylls), but their margins are not conspicuously overlapping. Regular repetition of similar elementary shoots along a rhizome may cause a question whether each elementary shoot represents a new branching order in a sympodial system with iterative branching. We did not observe buds in axils of foliage leaves, and one may speculate that the entire next elementary shoot develops in an axil of the foliage leaf. However, we did not find any robust evidence for a sympodial interpretation. In contrast to the axillary peduncles, the first cataphyll of an elementary shoot is not two-keeled. Also, rhizomes of phylogenetically related taxa (classified as Convallarieae) are monopodial ( Conran & Tamura, 1998). The short shoots of Convallaria , interpreted as monopodial, show a regular alternation of elementary shoots with cataphylls and foliage leaves, though only one elementary shoot a year is formed (see Irmisch, 1856).

Taxonomic relationships: —The new species resembles A. lingyunensis Lin & Guo but differs in longer leaf petioles (21–67 cm vs. 9–17 cm), longer lamina (20–46 cm vs. 15–22 cm), longer peduncle (1–3.8 cm vs. 0.5–1 cm), perianth tube shape (tubular, widened at the base vs. funnel-shaped), anther position (at the lower vs. middle part of the perianth tube), pistil shape (suddenly obconic to nearly umbrella-shaped vs. obconic gradually widened to stigma) and length (5–8 mm vs. 8–10 mm), wider stigma (4–8.6 mm vs. 3 mm). Both A. lingyunensis and A. xuansonensis include plants with white to purple perianth. Color morphs of A. xuansonensis are here formally treated here as varieties. Available material suggests that the differences in color of perianth correlate with petiole length. The occurrence of this correlation can be further tested when more populations of the species will be discovered.

Figures

FIGURE 1. Aspidistra xuansonensis. a, c, d. flowers of A. xuansonensis var. xuansonensis: top view (a), longitudinal section (c) and side view (d); b, e. flowers of A. xuansonensis var. violiflora: top view (b) and longitudinal section (e); f, g, h. A. xuansonensis var. xuansonensis: flowering plant (f), leaf blade (g), fruit (h).

FIGURE 2. Flowers of Aspidistra xuansonensis. a. flower with four tepals and bilocular ovary; b. flower with five tepals and bilocular ovary; c. flower with six tepals and bilocular ovary; d, e. flower with six tepals and trilocular ovary with low (d) and high (e) rate of stigma bifurcation; f. flower with seven tepals and quadrilocular ovary; g, h. groups of three (g) to seven flower buds on rhizome (h).As suggested by Vislobokov et al. (2014), flowers are dimerous pentacyclic in (a), 2,5-merous pentacyclic in (b), trimerous in (d-e) and 3.5-merous in (f).

FIGURE 3. Diagrams of shoot system of Aspidistra xuansonensis. a. Diagram of rhizome. The diagram shows an entire elementary shoot (its phyllomes are green), three final phyllomes of a previous elementary shoot (black) and two initial phyllomes of a subsequent elementary shoot (blue). Axillary buds red. Each elementary shoot possesses several cataphylls (lines on the diagram) followed by a foliage leaf (filled figures).The diagram shows physical orientation of the rhizome relative to Earth (bottom side on the figure).b. Diagram of a specialized axillary reproductive shoot (peduncle). Black, main axis and its cataphyll that subtends the peduncle; red, prophyll and hypsophylls of the peduncle followed by a schematic outline of a flower showing a typical orientation of the outer whorl tepals.