Atraphaxis selengensis O.V. Yurtseva & E.V. Mavrodiev, 2021

Yurtseva, Olga V., Badmaeva, N. K. & Mavrodiev, Evgeny V., 2021, A broadly sampled 3 - loci plastid phylogeny of Atraphaxis (Polygoneae, Polygonoideae, Polygonaceae) reveals new taxa: II. Atraphaxis selengensis spec. nov., and A. davurica Jaub. & Spach from Russian Transbaikalia, Phytotaxa 484 (1), pp. 44-74 : 64-65

1. Atraphaxis selengensis O.V. Yurtseva & E.V. Mavrodiev , sp. nov.

Type:— RUSSIA, Buryatia [Buryatskaya ASSR]: Selenginsky distr., sands at right bank of the river Selenga near Selenginsk , 8.08.1963, O.V. Daeva (MHA! holotype & isotype) ( Fig. 2E ) .

– A. frutescens auct., non (L.) K. Koch: Peshkova 1972: 51, Peshkova 2005: 63, Osipov 2001: 248.

Subshrub 15–40 cm tall, with annual shoots branched off the top of many-headed caudex (taproot) 5–50 mm in diam., or small shrub with annual shoots branched off the second-year shoots terminating caudex. Rounded root 3–5 mm in diam. and 100–150 cm long covered with fibrously desintegrating dark reddish-brown bark. Lignified shoots unarmed, simple or branched, at base 3–4 mm in diam., at the top 1–1,5 mm in diam., with reddish-brown wood covered by yellowish-gray to light brown fibrously disintegrating bark. Annual shoots straight, slender, 10–20 cm long, 0.3–1.0 mm in diam., finely ribbed, glabrous, creamy to yellowish-gray, leafy, with leaf blades gradually narrowed to the top of the shoot. Internodes 7–20(30) mm long.

Generative shoots terminated by thyrses 5–10 cm long with 3–8 well spaced cymes of 2–3 flowers, or by racemes of thyrses. Leaf blades leathery, glabrous, bluish-green, abaxially with prominent reddish midvein and oblique laterals. Bottom leaf blades 15–25(30) × 7–9 (12) mm, oblong to broadly elliptical, almost sessile or at a petiole 1 mm long, obtuse, shortly pointed or acuminate at the top, rounded or broadly cuneate at base, flat or slightly revolute and finely undulate at margin, with net of veins, slightly papillate at the base. Upper leaf blades 5–17 × 0.5–2.0 mm, linear-lanceolate to linear-subulate, almost sessile or at a petiole 1–1.5 mm, acute, revolute and finely crenulate at margin, with oblique lateral veins beneath. Ochreas 8–10(12) mm long, lanceolate-tubular, gradually acuminate, at base brownish and papillate, above filmy, transparent, with two light-brown lateral veins, later split in two lateral subulate lacinulas connected with truncate finely incised middle portion. Lateral lacinulas lanceolate, serrate-incised at margins, with a single vein. Ochreolas in thyrses 6–7 mm long, oblique funnel-shaped, inflated at base, filmy, at base brownish, above transparent, deeply split in two subulate-lanceolate or subulate-ovate lacinulas at both sides of extremely reduced linear leaf blade, each with light-yellow vein, fimbriate-lacerate or serrate-incised at margin. In flowering perianth is 5–6 mm long, with 5 segments green in the middle and white-pinkish at margin, finely crenulate and undulate, with prominent net of veins. Pedicel 2–3 mm long hidden in ochreola and joint to a filiform basal part of tube 0.7–1.0 mm long, which is terminated with cup-shaped or widely funnel-shaped extention 0.7–1.0 mm long and 1.0 mm in diam. Outer segments 2–3 × 2–3 mm, rotundate or oblong-ovate, outspread in flowering and fruiting. Inner segments 3.5–4.0 × 4.2–4.5 mm, broadly elliptical, oblong-ovate, or rotundate. Stamens 8, filaments 0.2 mm long, lanceolate, suddenly broaden at base. Styles 3, 0.3–0.5 mm long, connated at base to 1/5, with globular stigmas 0.2–0.3 mm in diam. Fruit trigonous, lanceolate, 3.5–4.5 × 1.8–2.0 mm, sides lanceolate, equal to the inner segments in fruiting, black, finely micro tuberculate, shiny.

Fl.— May–June. Fr.— June–Aug.

Distribution: —Buryatia, along the Selenga and Chikoy rivers, probably occurs in Mongolia along the Selenga River ( Fig. 12 ).

Ecology: —moving dune sands and pine forests along the Selenga, Chikoy, Khilok rivers.

Etymology:—Named after the Selenga river.

Chromosome number: —2n=16, left and right bank of the river Chikoy, 560 m ( Ekimova et al. 2009, Chepinoga 2014) sub A. frutescens (L.) K.Koch.

Taxonomic relationships: —Identified as Tragopyrum lanceolatum M.Bieb. nom. illeg. superfl. in herbarium collections (LE, MW) since the 19th century. In “Flora of USSR” ( Pavlov 1936) and “Floras” of Siberia ( Krylov 1930, Peshkova 1972, Ivanova 1979, Lovelius 1979, Kashina 1992, Osipov 2001) is mistaken for Atraphaxis frutescens (L.) K.Koch and reported from Russian Transbaikalia. It resembles A. frutescens in loose terminal thyrses with well spaced cymes of flowers, but has leafy thyrses, longer ochreas, ochreolas and styles. It differs by the perianth shape and black fruits. Atraphaxis frutescens is absent from Russian Transbaikalia but common in East Europe, Kazakhstan, Altaisky Kray, the Altai Republic ( Pavlov 1936), Krasnoyarsk Region, Khakassia, Tuva ( Kashina 1992), Eastern Mongolia ( Grubov 1982, Gubanov 1996), China ( Borodina 1989, Bao & Grabovskaya-Borodina 2003).

Atraphaxis selengensis resembles A. manshurica Kitag. ( Nakai et al. 1936: 75) from Manchuria ( China) in leafy thyrses with well spaced cymes of flowers, transparent glossy ochreas and ochreolas, perianth with cup-shaped tube extention and tepals directed to sides in fruiting. Atraphaxis selengensis differs from A. manshurica by broader bottom leaf blades and longer ochreas. Our preliminary study has shown that A. selengensis and A. manshurica share the ITS1–2 region but fall in different subclades in plastid topology ( Fig. 1 ).

Atraphaxis selengensis is grouped with A. davurica in plastid phylogeny but differs by morphology of the thyrses, leaf blades, and perianth with extremely short filiform low part of perianth tube and a cup-shaped extention, and the outer tepals directed to sides in fruiting.

Figures

FIGURE 1. The results of ML and BI analyses applied to the combined chloroplast data set (trnL(UAA) intron + trnL-trnF IGS and rpl32- trnL (UAG) IGS) of Atraphaxis with Bactria ovczinnikovii taken as an outgroup. Numbers above or below branches indicate the aLRT support values equal or more than 0.7 / the posterior probabilities from Bayesian analysis equal or more than 0.9.

FIGURE 2. Atraphaxis davurica (A), A. davurica var. chikoensis (B), A. pungens (C), A. selengensis (D–E) from RUSSIA, and A. frutescens from MONGOLIA (F). A—Buryatia, Mukhorshibirsky d., Podlopatki, Abramova et al. (MW). B—Buryatia, Khentei-Chikoy Highlands, Anagustay, Maximova (LE). C—Khakassia, Askiz d., Kazanovka, Skvortsov (MW). D—Buryatia, Selenginsk, Schukin (LE). E—Buryatia, Selenginsk, Daeva (MHA, Holotype). F—Khovd aimag, Bulgan, Gubanov 7503 (MW).

FIGURE 12. Distributional map for Atraphaxis species from Russian Transbaikalia: