Dioscorea confusa Raz, 2016

Raz, Lauren, 2016, Untangling the West Indian Dioscoreaceae: New combinations, lectotypification and synonymy, Phytotaxa 258 (1), pp. 26-48 : 31

5. Dioscorea confusa Raz , nom. nov. Rajania wrightii Uline ex Knuth (1917: 221) . Lectotype (designated here):— CUBA. Without locality, 1860-64, Wright 1712 ♂ (lectotype NY “2 A ”!, isolectotypes K “2 B ”!, S “1 A ”!, US “2 A ”!)

Notes: Cuban endemic. The interpretation of Rajania wrightii has been problematic from the start. The protologue includes no description and no diagnosis, just the ascription “Uline in msc.” followed by a list of synonyms and specimen citations: Wright 1712 p.p. (♀ ♂), Valenzuela s.n. (♂ ♀), and Curtiss 506 p. p. (♂). Knuth did include a description in the 1924 monograph, but it is based on so many disparate elements that it is rendered meaningless.

The species represented by the Curtiss 506 duplicates from the Isle of Pines (Isla de la Juventud) in Cuba (BM, CM, F, GH) is not present among any of the Wright collections that I have seen. The Curtiss material has a rotate flower with deltate tepals as in D. bahamensis ; it corresponds most closely to the type of R. prestoniensis , considered here to be a wider-leaved form of D. bahamensis .

I was not able to locate the Valenzuela material, but there are clues to its identity from the literature. Knuth (1924) cited among the exsiccatae of R. psilostachya “Valenzuela ♀ ”, which is likely to be on the same sheet as the staminate material cited for R. wrightii , (there is no “p.p.” appended to either citation). Richard (1850) cited a Valenzuela collection (without number or reference to the sex of the specimen) and mentioned that the species was found “near Havana ”. The Richard name was considered by Knuth to be a synonym of R. psilostachya , based on his examination of the Valenzuela material, and this determination is consistent with the narrow distribution of D. psilostachya . If the staminate material was also collected near Havana, then it would have to be either D. psilostachya , or D. bahamensis .

The remaining specimens cited as R. wrightii by Knuth (1924) are four Ekman collections from Eastern Cuba; all correspond to what is here called D. introrsa .

It is almost impossible to know which of the Wright 1712 elements Knuth (1917, 1924) considered in his formulation of R. wrightii . The elements cited here as the type collection of D. confusa , are those that cannot be assigned to any other species, and correspond to modern collections from southern central Cuba. The plants are unique in having staminate inflorescences congested (internodes between cymes reduced) with sessile cymes of white, globose flowers that remain light in color when dry. A full treatment is forthcoming in the series Flora de la República de Cuba.