Cytisus semerenkoanus Sennikov & Val.N.Tikhom., sp., 2024

Sennikov, Alexander N. & Tikhomirov, Valery N., 2024, Atlas Florae Europaeae notes, 33. Taxonomic synopsis of East European species of the Cytisus ratisbonensis group (Fabaceae), PhytoKeys 238, pp. 157-197 : 157

4. Cytisus semerenkoanus Sennikov & Val.N.Tikhom., sp. hybr. nov.

Type.

Belarus. Gomel Region, Dobrush District, vicinities of Dobrush Town , margin of pine forest with moss cover, 19.05.1979, L.V. Semerenko & I.V. Shvets (holotype MSK, isotypes MSK, MSKU). Fig. 5 .

Etymology.

The species name is given in honour of Larisa Vasilievna Semerenko ( Parfionaŭ et al. 2018), who advanced our knowledge by her studies on the karyology and biology of Cytisus in Belarus.

Description.

Upright shrubs with erect, basally ascending stems up to 60(80) cm tall and long branches. Leaves with elliptic to obovate leaflets, sparsely hairy to subglabrous above, with lax hairs 0.2-0.6 mm long below, petioles sparsely covered with appressed and subpatent hairs. Flowers strictly lateral, 1-4 in axils, on pedicels 3-6 mm long, yellow; calyx 10-12 mm long, with appressed and subpatent hairs 0.4-0.9 mm long; standard suborbicular, hairy to subglabrous above.

Distribution.

Europe: Poland, Moldova, Belarus, Ukraine, Russia. Asia: Russia (Caucasus), Abkhazia.

Ecology.

In the forest zone, this taxon is found in dry forests on rich soils (oak forests and mixed broadleaved-pine forests with steppe plants), mostly in open places; in the forest steppe and steppe zones, it occurs in sparse forests and open steppe-like places.

Chromosome counts.

2n = 50 ( Parfionaŭ et al. 1975, as Chamaecytisus sp.); material collected from native populations in Gomel Region; vouchers at MSK.

Notes on nomenclature.

Kreczetowicz (1940) described an alleged hybrid between C. ruthenicus and C. elongatus under the name C. czerniaevii , but the original material of the latter name belongs to C. elongatus rather than to the hybrid. For this reason, the hybrid is described here under a new name.

Notes on taxonomy and distribution.

Kreczetowicz (1940) described this taxon as a hybrid between Cytisus lindemannii (our synonym of C. elongatus ) and C. ruthenicus , and this interpretation was accepted by Tzvelev (1987). Based on the intermediate morphology, we agree on the presence of hybrids between C. ruthenicus and C. elongatus . The distribution of C. semerenkoanus extends much further eastwards and northwards than the current distribution of its presumed parent, C. elongatus , which we explain by the extinction of the latter due to postglacial climate changes and hybridisation processes.

Figures

Figure 5. Holotype of Cytisus semerenkoanus Sennikov & Val. N. Tikhom.