Pollen morphology ofZehnerias.l. (Cucurbitaceae)

Open Access
Publisher Website
Google Scholar
Abstract
In order to provide additional data for the proposed subdivision of the palaeotropical genus Zehneria (Cucurbitaceae, tribe Benincaseae, subtribe Cucumerinae) by De Wilde and Duyfjes (2006) De Wilde, W. J. J. O. and Duyfjes, B. E. E. 2006a. Redefinition of Zehneria and four new related genera (Cucurbitaceae), with an enumeration of the Australasian and Pacific species.. Blumea, 51: 1–88. [Google Scholar] into five genera (Indomelothria, Neoachmandra, Scopellaria, Urceodiscus and Zehneria s.s.) pollen was examined using light and scanning electron microscopy for 18 Zehneria species including representatives of each of the proposed subdivisions, plus one species of the neotropical genus Melothria to which Zehneria once belonged. The pollen of Indomelothria, Scopellaria and Urceodiscus are described for the first time. Indomelothria, Neoachmandra and Zehneria s.s. have the same pollen type (3‐colporate, microreticulate to reticulate), which cannot be distinguished from that of Melothria. Scopellaria deviates by its irregularly striate‐reticulate ornamentation and short colpi, and Urceodiscus by its striate‐reticulate ornamentation. This result supports separation of Scopellaria and Urceodiscus as separate genera, but neither supports or rejects the segregation of Indomelothria and Neoachmandra. The pollen type shared by Indomelothria, Neoachmandra and Zehneria s.s. fits very well in the Cucumerinae. However, the striate‐reticulate ornamentation of Scopellaria and Urceodiscus pollen is unknown within this subtribe, and leaves some doubt with respect to the (sub)tribal assignment of both Scopellaria and Urceodiscus. Based on pollen morphology alone, the African Neoachmandra(?) peneyana does not belong to the tribe Benincaseae. Within the Cucurbitaceae, the 6‐aperturate pollen type of Neoachmandra (?) peneyana occurs only in the exclusively neotropical tribe Sicyeae.