Climacoptera, Botschantzev, 1956

Mosyakin, Sergei L. & Roalson, Eric H., 2017, New nomenclatural combinations in Pyankovia (Chenopodiaceae), Phytotaxa 319 (3), pp. 263-270 : 264-265

Circumscription of Climacoptera and Pyankovia : recent molecular phylogenetic, anatomical, and morphological evidence

Molecular phylogenetic studies not only confirmed the generic status of Climacoptera sensu stricto but also demonstrated that at least one species previously placed in this genus, C. brachiata ( Pallas 1803: 30) Botschantzev (1956: 114) belongs to a distinct clade phylogenetically remote from the remaining species of Climacoptera . The new genus Pyankovia was described to accommodate this species (Akhani et al. 2007).

Further molecular studies by Wen et al. (2010) showed that one more species, C. affinis (C.A. Meyer ex Schrenk 1843: 360) Botschantzev (1956: 114) does not belong to Climacoptera sensu stricto and is more closely related to Pyankovia . The group of C. brachiata and C. affinis was informally called by Wen et al. (2010) “ Climacoptera I”, and the remaining taxa of Climacoptera ( sensu stricto) were placed in “ Climacoptera II ”. Wen et al. (2010) noted that “ Climacoptera I consists of Climacoptera brachiata and Climacoptera affinis <…>, which does not support the previous treatment of C. brachiata as a monotypic genus, Pyankovia (Akhani et al. 2007) . <…> Several shared morphological features such as habit, leaf shape, leaf anatomy, and the winged fruiting perianth support their close affinity (Table 3)”. However, most of the characters provided by Wen et al. (2010: Table 3) for these two groups are either identical or at least greatly overlapping. The recently reported characters of leaf anatomy seem to be more reliable in separating Pyankovia from Climacoptera . In particular, Wen & Zhang (2011) further confirmed the “ Climacoptera I and II” phylogenetic split with data of comparative anatomy of photosynthetic organs. It has been demonstrated ( Wen & Zhang 2011) that C. affinis and C. brachiata belong, together with several other studied species (placed in at least four genera), to the “ Salsola kali anatomical type ”, while all other sampled taxa of Climacoptera were placed in “ Climacoptera type II”. Both these anatomical types belong to the main type “Salsoloid without hypodermis (Salsoloid −H)”. Wen & Zhang (2011: 729) further commented that “the genus Climacoptera should be divided into two parts, Climacoptera I consisting of C. affinis and C. brachiata , and Climacoptera II consisting of the other species. C. ferganica , C. lanata , C. obtusifolia , and C. subcrassa belong to Climacoptera II clade and have the Climacoptera type II anatomical structures. Leaves of these four species are decurrent. The foliar adaxial epidermis is adpressed against the stem and covers the branches almost completely, which may be related to the leaf structure, where the palisade mesophyll and the bundle sheath of the leaf are interrupted adaxially”. Despite these findings, no taxonomic changes were proposed by Wen et al. (2010), Wen & Zhang (2011), or by subsequent authors, who still applied the generic name Climacoptera to these groups.

In our opinion, in addition to other more elusive vegetative characters and not so easily observable anatomical structures, the most evident and reliable morphological synapomorphy of Pyankovia in its new circumscription (corresponding to Climacoptera I group by Wen et al. 2010) that distinguishes it from species placed in Climacoptera sensu stricto ( Climacoptera II group) is the ovate or spathulate membranaceous appendages in the apical parts of anthers. As far as we are aware, that character has not been discussed in recent publications as a diagnostic one, with the exception of Akhani et al. (2007: 944, 949), who mentioned “small obtuse anther appendages” in the text and in the original generic diagnosis: “antherae lineares, per 1/3 vel 2/5 longitudinem partitae appendicibus sessilibus albis obtusis ornatae”. This character is also peculiar to one more taxon of the former Climacoptera , i.e. Climacoptera roborowskii (Iljin 1955: 136) Grubov (1966: 98) from Central Asia (Xinjiang Uyghur Autonomous Region of China). C.roborowskii is closely related to C.affinis ( Grubov 1966) , or sometimes considered conspecific with it( Zhu et al.2003). However, Iljin (1995: 138) reported that his new species differs from S. affinis in having prostrate and much-branched habit, more dense pubescence that is retained in plants at maturity, and shorter boat-shaped leaves: “Appropinquat ad Salsolam affinem C. A. M. sed habitu, caulibus et ramis prostratis, densius pubescentibus, pubescentia non caduca, foliis manifeste navicularibus sat distat”. Grubov (1966: 99) added that perianth segments in C. roborowskii are also evidently more pubescent than those in C. affinis , and that all these morphological differences are not negligible because they consistently occur in plants from at least two localities in Kashgaria (Xinjiang) which are geographically well separated from the main range of C. affinis and from ranges of all other species of Climacoptera .

The morphological differences and geographical disjunction between these two taxa ( Grubov 1966), as well as the study of the high-resolution digital images of the type and other authentic specimens of S. roborowskii (deposited in LE), indicate that the last taxon deserves the rank of species.

Mosyakin already commented (personal communication cited in Hernández-Ledesma et al. 2015: 341) that, in the light of recent data, Pyankovia should include at least three species distributed from southeastern Europe through the Caspian area, the Caucasus, and Iran to Central Asia. Two species and one section are now formally transferred to Pyankovia here. The following diagnostic characters were reported by Akhani et al. (2007: 944) for Pyankovia : “the characteristic opposite leaves (except uppermost floral leaves), small obtuse anther appendage, and presence of a spinulose indumentum with long smooth articulate hairs” and also vertical seeds. In its updated circumscription, this genus also contains species with alternate and subopposite leaves, short trichomes, and horizontal seeds. However, the characters of peculiar anther appendages and leaf anatomy seem to be at present the most reliable ones.