Chenopodium amurense, Ignatov, 1986

Mosyakin, Sergei L. & De Lange, Peter J., 2018, New combinations for three taxa of the Oxybasis glauca aggregate (Chenopodiaceae) from Australasia, East Asia, and South America, Phytotaxa 350 (3), pp. 259-273 : 263-264

Chenopodium amurense from the Russian Far East

Ignatov (1986: 111) reported in the protologue that Chenopodium amurense differs from C. glaucum in having lobate (normally trilobate) leaves and narrow spathulate tepals of pentamerous flowers (trimerous flowers usually have wider tepals). Ecologically this taxon seems to be a predominantly non-weedy species confined to sandy alluvial habitats of the Amur River and adjacent areas.

Mosyakin (1993: 74) briefly commented that Chenopodium amurense may be related to C. ambiguum . That assumption was based mainly on some similarity in leaf shape characters of these two taxa. Feodorova (2017: 9) assumed that C. glaucum subsp. orientale Voroshilov (1984: 36) is the same taxon as C. amurense and noted that “both these taxa appear to be synonymous with C. ambiguum R. Br. ”. However, the original description of subsp. orientale does not match the characters reported for C. amurense . In particular, Voroshilov (l.c.) noted that his new taxon differs from subsp. glaucum only in having leaves green on both sides (occasionally only young leaves being slightly glaucous and mealy beneath). The leaves in subsp. orientale were described as elongate to linear-oblong in shape, obtuse at apex, and sinuate-dentate at margins (“Folia petiolata, oblonga vel lineari-oblonga, obtusa, margine sinuato-dentata ad subintegerrima, utrinque viridia, novella tantum vix glaucescentia”; Voroshilov 1984: 36), as in subsp. glauca , but not trilobate or deltoid as in C. amurense . Ignatov (1988: 24) also commented that C. glaucum subsp. orientale differs from subsp. glaucum only in the absence of mealy indumentum on the lower surface of leaves and is not identical with his C. amurense . Holotypes of both C. glaucum subsp. orientale and C. amurense are deposited in MHA ( Voroshilov 1984,

Ignatov 1986, Stepanova 2015). The first author of the present article (Sergei Mosyakin) studied the type specimens of both these entities during his visits to MHA in the 1990s and also concluded that C. glaucum subsp. orientale and C. amurense are different taxa from the morphological point of view, as well as C. amurense and C. ambiguum , which differ, in particular, in their perianth characters, leaf shape, and succulence. The chromosome count reported for C. amurense ( Probatova & Sokolovskaya 1990) indicate that that taxon is a diploid with 2n = 18, so its identity with tetraploid C. ambiguum (here recognized as Oxybasis ambigua ) is also very unlikely.

Chenopodium amurense was recognized as a distinct species in several publications on the flora of the Russian Far East ( Ignatov 1988, Czerepanov 1995a, 1995b, Schlotgauer et al. 2001, Pavlova & Probatova 2006, Kryukova 2010, Lomonosova 2012, Kasatkina 2013, Tzyrenova & Kasatkina 2013, Mel’nikova & Kryukova 2015, etc.). Most probably it also occurs in adjacent regions of China (see Zhu et al. 2003), and possibly can be also expected in Korea and/or Japan.

Kasatkina (2013) and Tzyrenova & Kasatkina (2013) noted that Chenopodium amurense occurs on banks of the Amur River and some other water bodies together with several other predominantly alluvial species considered endemic or subendemic for the region, such as Corispermum elongatum Bunge (in Maximowicz 1859: 224), C. macrocarpum Bunge (in Maximowicz 1859: 226), Gnaphalium mandshuricum Kirpicznikov & Kuprianova ex Kirpicznikov (1960: 298) , Juncus amuricus ( Maximowicz 1859: 296) V.I. Kreczetowicz & Gontscharow (1935: 516) , Rumex amurensis F. Schmidt (in Maximowicz 1859: 228), Symphyllocarpus exilis Maximowicz (1859: 151 ; see also Smoljaninova 1960), and some others. Some of these species and their communities and habitats are in need of conservation. Chenopodium amurense was included in the Red List of the Jewish Autonomous Region of the Russian Far East, but was soon excluded from it (data from the site Strictly protected natural areas of Russia —ОсОбО ОхранЯемые прирОдные территОрии РОссии: http://oopt.aari.ru/; see also Mel’nikova & Kryukova 2015) and is not listed now in the Red Data Book of the Jewish Autonomous Region ( Schlotgauer 2006).

Considering the morphological and ecological distinctiveness of that predominantly alluvial taxon and its geographic isolation from the main part of the native range of Oxybasis glauca , we propose here the species-rank transfer of Chenopodium amurense to Oxybasis (see below).