The April 2014 edition of the New Journal of Botany (Volume 4 Number 1) contains the following article: British Sorbus (Rosaceae): six new species, two hybrids and a new subgenus by T. C. G. Rich, D. Green, L. Houston, M. Lepší, S. Ludwig and J. Pellicer.
The new species are Evans’s Whitebeam (Sorbus evansii), Green’s Whitebeam (S. greenii), Herefordshire Whitebeam (S. herefordensis), Rich’s Whitebeam (S. richii), Sell’s Whitebeam (S. sellii) and Observatory Whitebeam (S. spectans). These all grow around the Severn and Severn estuary and the article gives maps and details of locations with detailed descriptions of the species should anyone want to go and see them.
The new hybrids are Sorbus aucuparia x S. minima where a single example has been found in the Brecon Beacons and Sorbus porrigentiformis x. S. torminalis with two trees on a cliff in Monmouthshire.
All these species and hybrids have been defined as distinct using genetic analysis techniques.
The new subgenus is Triparens, set up to cover the Swedish Whitebeam (Sorbus intermedia) and S. x liljeforsii, the backcross of S. intermedia with S. aucuparia.
Details of the New Journal of Botany are here: http://www.bsbi.org.uk/NJB_Flyer.pdf