Pollen morphology and systematics of palaeotropicalPhyllanthusand related genera of subtribe Phyllanthinae (Euphorbiaceae)

Abstract

The observations of pollen from 27 species of subtribe Phyllanthinae using scanning electron microscopy reveal considerable morphological diversity in palaeotropical Phyllanthus and the related palaeotropical genera Breynia, Glochidion, and Sauropus. The tribe appears to be monophyletic, but the pollen morphology does not support the monophyly of Phyllanthus or Sauropus. Within Phyllanthus, the pollen characters suggest a close relationship between the subgenera Emblica and Phyllanthodendron. They also reveal a surprising morphological congruence between the pollen grains of section Ceramanthus (subgenus Isocladus) and those of subgenus Eriococcus, although it is not clear whether this similarity is homoplastic. The presence of diploporate colpi is a synapomorphy uniting Breynia and Sauropus, but may be homoplastic in Phyllanthus. The affinities suggested by the morphological features of the pollen in the Phyllanthinae are concordant with recent molecular phylogenies.

Pollen morphology of Chinese Glochidion (Phyllanthaceae) and its taxonomic implications

“…The pollen morphology of Glochidion species sampled for the present study is largely consistent with previous observations (Deng 1992, Sagun and Van der Ham 2003, Webster and Carpenter 2008. However, some additional new types were observed, such as the confluent colpi of some pollen grains of G. pseudo-obscure ( Fig.…”

“…subgen. Phyllanthodendron (3–5‐colporate) both have fewer colpi with a single endoaperture (Wei et al , Webster and Carpenter ), while pollen grains of Breynia (4–12‐colporate) and Sauropus (3–17‐colporate) are all multi‐colporate, and each colpus usually has two endoapertures (Sagun and Van der Ham , Webster and Carpenter ).…”

“…P. emblica Linnaeus), shrubs ( P. hainanensis Merrill), herbs ( P. urinaria Linnaeus), free‐floating aquatics ( P. fluitans Bentham ex Müller Argoviensis), rheophytes ( P. rheophyticus M. G. Gilbert & P. T. Li), scandent shrubs ( P. reticulatus Poir) and succulents ( P. mirabilis Müller Argoviensis) (Macbride , Webster , Chantaranothai , Li and Gilbert ). Extensive previous palynological studies of Phyllanthus s.s. have revealed that the pollen morphology of this genus is also very diverse (Punt , , Punt and Rentrop , Bor , Meewis and Punt , Lobreau‐Callen et al , Webster and Carpenter , , Wei et al , Sagun and Van der Ham , Santiago et al , Furness , Chen et al ), including oblate to prolate shapes; 3–11‐zonocolporate (colpori with one or two endoapertures), syncolpate, pantocolporate, pantoporate, zonoporate, or even inaperturate aperture patterns, and perforate, reticulate, vermiculate and pilate exine ornamentations. In addition, within taxa with reticulate exine, uni‐reticulate, bi‐reticulate exine, micro‐ reticulate and coarsely reticulate, and lumina with and without free sexine elements have all been reported within the genus.…”

“…The diversity of aperture types and exine ornamentation patterns observed in pollen grains of species in Phyllanthus s.s. have been used in species delimitation (Wei et al , Chen et al ). However, the genus Glochidion has rarely been referred to in palynology (Deng , Sagun and van der Ham , Webster and Carpenter ). So far only about 20% (ca 60) of its species have been studied palynologically, and micrographs are available for less than 7% (ca 20) of the total species of this large genus.…”

Phylogenetic reconstruction prompts taxonomic changes in <I>Sauropus</I>, <I>Synostemon</I> and <I>Breynia</I> (<I>Phyllanthaceae</I> tribe <I>Phyllantheae</I>)

“…Voigt were obtained from specimens (see Table 3). All pollen characters were recorded from Sagun & Van der Ham (2003) and Webster & Carpenter (2008).…”