Conospermeae (Proteoideae) pollen morphology and its phylogenetic implications

Abstract

Pollen morphological trends in modern taxa, the fossil pollen record, andcomparative palynology can be useful aids to taxonomy and indicators ofevolutionary lineages. In Conospermeae, each species and genus has a distinctpollen morphology character set, although individual characters may not betaxon-specific. Aperture form in Conospermeae may be consistent or diversewithin a genus, and has limited or no taxonomic value above the generic level;whereas with the exception of Beauprea Brongn. & Gris., sculptural type is consistent within a genus and often withinsubtribes. In the light of generic characters, a review of fossil pollenaffiliates of Conospermeae indicates that the fossil record ofStirlingia Endl. and SymphionemaR.Br. is not as extensive as previously thought. Conospermeae pollenmorphology thus far investigated, together with the fossil record, suggeststhe tribe is not monophyletic but includes several evolutionary lineages.Synaphea R.Br. and Conospermum Sm.(Conosperminae), together with Stirlingia(Stirlingiinae), may have close ties with Persoonioideae.Isopogon R.Br. ex Knight andPetrophile R.Br. (Petrophilinae) can be sculpturallyaligned with Symphionema (Cenarrheninae) and severalProteeae genera, and to a lesser degree, AgastachysR.Br. (Cenarrheninae) with Aulax (Proteeae). Of themonotypic genera, pollen of Beaupreopsis Virot andCenarrhenes Labill. are alike, and that ofDilobeia Thouars. has similarities to these genera butis also not unlike pollen of Bellendena R.Br.(Bellendenoideae). Beauprea pollen is morphologicallyunique among the Proteaceae in having colpoid apertures and diverse sculpturaltypes. Pollen of Beauprea species so far investigatedappear to more closely resemble pollen of Persoonioideae than that of otherConospermeae genera. The fossil record, however, indicates thatBeauprea pollen has sculptural analogues in allProteaceae subfamilies, suggesting that its relationship to the rest of thefamily is complex. The fossil pollen record and patterns in modern pollenmorphology can confirm or suggest taxonomic and phyletic relationships, but for firmer resolution are best used in conjunction with other lines of evidence.