Commelina guyanensis Seub.

Commelina guyanensis Klotzsch ex Seub. Commelina guyanensis Klotzsch ex Seub. (Seubert in Martius 1855: 262). – Commelina guianensis Klotzsch (Klotzsch in Schomburgk 1849: 1064), nom. not effectively published. Syn. nov. Type material GUYANA • s.loc., In swampy areas of the savannah and on the banks of rivers; s.dat.; fl.; M. R. Schomburgk 387; neotype: P [P01795521]!, designated here. Accepted species Commelina diffusa Burm.f. Nomenclatural remarks No specimens were cited by either Klotzsch (Schomburgk 1849) or Martius (1855). However, while visiting the P herbarium, we came across a specimen (P 01795521) that perfectly matches the diagnoses provided by both authors. Furthermore, the label is from the same expedition as P 00752552, which is annotated as being the type of C. platyphylla Klotzsch ex Seub., which shares the same publication record as C. guyanensis. Therefore, we designate this specimen as the neotype for C. guyanensis, also fixing its application as conspecific with C. diffusa. Remarks Commelina guyanensis Klotzsch ex Seub. has been traditionally regarded as a synonym of C. rufipes. Klotzsch’s original description (Schomburgk 1849) was done solely in German, lacking a Latin diagnosis or description, making the name not effectively published. However, the German diagnosis described the species as a perennial herb growing on swampy savannah and riverbanks, which prevents it from being conspecific with C. rufipes (a species from the non-flooded understory of rainforests). Later, Martius (1855) finally provided a Latin diagnosis, which characterised the species as having glabrous stems, leaf-sheaths margin setose with light brown hairs, leaf-blades lanceolate with acuminate apex and vinaceous veins, inflorescences subterminal and “short-pedunculate” [sic], spathe conduplicate (i.e., base free), “pedicels 2” (i.e., with 2 developed cincinni) with the upper one hirtellous and “sterile” [sic], capsules glabrous, and seeds free. These characters make it impossible for this name to represent a synonym of C. obliqua, let alone C. rufipes. However, both diagnoses confidently place the species in the C. diffusa group. As aforementioned, the selected neotype is conspecific with the current circumscription of C. diffusa. Thus, this name is excluded from the synonymy of C. rufipes and placed under the synonymy of C. diffusa.