Introduction
The reasons for treating Tilia dictyoneura as a subspecies of T. paucicostata are set out and discussed in Pigott (2012: 167–174), but the subspecific name was not validly published there, because the full and direct reference given for the basionym was not to the work in which that basionym was validly published.
Tilia dictyoneura was described by V. Engler (1909: 86) and, although the precise date of publication is not known, it must have been late in the year as Schneider (1909: 369), in a ‘Lieferung’ of his handbook published on 25th August of that year, also provided a description of the species, attributing it to ‘V. Engl. MSS’ but noting that he was uncertain about when and where Engler’s publication would appear (‘Ich konnte nicht erfahren, wann und wo Englers Arbeit erscheint’). Although publishing Tilia dictyoneura as a ‘nov. spec.’, Engler (1909: 86) referred to ‘C.K. Schneider, Handb. Laubholzk. II (1909) 369; t. 250, h–k’, in the synonymy, although this appeared as if Schneider had not distinguished the species from T. paucicostata. In spite of this ambiguity, however, the provision of Art. 41.2(a) of the International Code of Nomenclature (McNeill et al., Reference McNeill, Barrie, Buck, Demoulin, Greuter and Hawksworth2012) cannot be applied to make the citation in Pigott (Reference Pigott2012) acceptable because in Engler’s publication there was reference to Schneider’s, clearly earlier publication. The necessary new combination is validly published here.
New Combination
Tilia paucicostata Maxim. subsp. dictyoneura (V.Engl. ex C.K.Schneid.) Pigott, comb. nov. – Basionym: Tilia dictyoneura V.Engl. ex C.K.Schneid., Ill. Handb. Laubholzk. 2: 369 (25 August 1909). – Lectotype designated here: Specimen 5733 collected by Giuseppe Giraldi in July 1899 from Ngo-san (then in Shaanxi province but near the eastern border and now shown in Shanxi province on maps) in Herb. A. Biondi in Florence (FI), Italy (illustrated in fig. 9.39(a) in Pigott, Reference Pigott2012: 171).
Although this lectotype was also designated in Pigott (2012: 171), this was under the presumption that Tilia dictyoneura had been first published by V. Engler; in order to avoid any doubt as to its effectiveness in establishing the type of T. dictyoneura C.K.Schneid., this designation is repeated here. Schneider saw no material of Tilia dictyoneura and based his description on that of Engler (and on Engler’s leaf illustrations which Schneider reproduced); consequently the six specimens cited by Engler (1909: 86) constitute original material (Art. 9.3(a)) of Schneider’s name; the lectotype selected above is one of these specimens.
Acknowledgements
I thank Katherine Challis for drawing my attention to this oversight and consequent error, and her and the late Dr R. K. Brummitt for help and advice in its correction. I thank Prof. J. McNeill for his expert changes to my presentation and text.
