Comparative pollen morphology and taxonomic ... - CNCFlora

104 R.L.B. de Borges et al. / Review of Palaeobotany and Palynology 154 (2009) 91–105
Table 4
Summary of pollen characteristics of Eriocaulaceae genera
Taxa No. of
studied
spp.
Carpocephalus, andGroup2— S. sect. Eulepis together with S. sect.
Thysanocephalus.
Thus, pollen data allied with others, raise the possibility of
separating Syngonanthus into two distinct genera, as proposed by
M. J. G. Andrade (unpubl. data.). The homogeneity of Syngonanthus
sect Eulepis with 2-zonasulcate pollen grains is strong evidence
supporting the new genus, but the position of S. sect. Thysanocephalus
with spiraperturate pollen grains needs more study.
According to Hensold and Giulietti (1991), the genus Rondonanthus
appears to combine characteristics from both the Eriocauloideae and
Paepalanthoideae subfamilies. Rondonanthus was the only representative
of Paepalanthoideae having a thick exine, a characteristic found
in the species of Eriocaulon. However, in this latter genus, the nexine is
thicker than the sexine, whereas the sexine and nexine are of equal
thickness in Rondonanthus.
The genera Paepalanthus and Syngonanthus demonstrated the greatest
variation in pollen characteristics, but only the zonasulcate species of
Syngonanthus sect Eulepis can be differentiated from the others. All of
the characteristics of Actinocephalus fit with those of Paepalanthus, as
recorded by Santos et al. (2000) in studying species of both genera. A more
detailed study of these pollen grains under transmission electron
microscopy could provide important data for the taxonomy of the
Eriocaulaceae, especially in terms of a better diagnosis of their apertures.
5. Conclusion
Size
class
Subfam. Eriocauloideae
Eriocaulon 4 Medium Spiraperturate, 2–3 apertures;
interapertural exine in a
crosshatch pattern
Subfam. Paepalanthoideae
Actinocephalus 6 Small to
medium
Apertural type Exine layers under LM Spines Granules
Spiraperturate, only one spiral
(helicoidal) or two spirals in
Blastocaulon 2 Small
varied arrangement
Spiraperturate, only one spiral
(helicoidal)
Lachnocaulon 2 Small Spiraperturate, only one spiral in
tennis ball pattern
Leiothrix 9 Medium Spiraperturate, perfect spiral
(helicoidal), or in tennis ball
pattern
Paepalanthus 15 Small to
medium
Spiraperturate, many
arrangements
The stenopalynous condition stated to Eriocaulaceae family is not
well-supported here, because pollen characteristics are usefull to the
characterization of some taxonomic groups. This study of the diversity of
Eriocaulaceae pollen brought to light characteristics previously unrecorded:
the grooved spines of Tonina fluviatilis and the 2-zonasulcate
grains of pollen of Syngonanthus sect. Eulepis. Furthermore the pollen
grains of 26 species are described here for the first time and 41 species
have been subjected to more detailed examination through SEM.
SbN Obtuse microspines, regularly
distributed
S=N but SNN inA. denudatus Acute spines and acute and obtuse
microspines with irregular
distribution
Undifferentiated Acute spines with acute and obtuse
microspines disperse among they
SNN Acute spines with acute (larger) and
obtuse (smaller) microspines
disperse among they
Undifferentiated but S=N inL. flavescens
and L. plantago
Undifferentiated but SNN inP. applanatus
and P. comans and S=N inP. bromelioides
and P. giganteus
Acknowledgments
Acute (micro)spines with irregular
distribution
Acute spines and acute and obtuse
microspines with irregular
distribution
The authors wish to express their thanks to: Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho
Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and
Ministério de Ciência e Tecnologia (MCT) for financial support and
grants; IMSEAR for permitting use of the SEM; directive board of the
herbaria HUEFS, MU, SP and SPF for providing pollen samples;
Dr. Raymond Mervin Harley (RBG, Kew) for critical reading of the text;
Mrs. Gisele Pinto Rocha (UEFS) for technical assistance with SEM;
Mrs. Neuza Magalhães Moraes Santos (SISBI/UEFS) for providing copies
of many of articles cited on this paper; Drs. Maria José Gomes de Andrade
(UNEB), Paulo Takeo Sano (USP) e Vera Lucia Scatena (UNESP) for giving
some specimens. Authors are deeply thankful to three anonymous
referees of RPP for their suggestions and corrections.
Appendix A. Specimens investigated
Absent
On the edge of exine
strips and irregularly
scattered
Few, distributed close
to the spines
On the edge of exine
strips and between
the spines
Absent, except for L.
plantago (Mart.) Giul.
Irregularly distributed
and on the edge of
exine strips
Philodice 1 Small Spiraperturate, one aperture in
different arrangements
S=N Acute microspines Absent
Rondonanthus 1 Medium Spiraperturate, one aperture in S=N Acute spines and acute and obtuse Rare
varied arrangement
microspines with irregular
distribution
Syngonanthus 14 Small to Zonasulcate (2 apertures), S=N but undifferentiated in S. caulescens, S. Acute spines with convex walls and Irregular distributed
medium spirapertures in many
cipoensis, S. schwackei and SbN inS. acute and obtuse microspines and on the edge of
arrangements
imbricatus, S. vernonioides
exine strips
Tonina 1 Small⁎ Spiraperturate – Acute and obtuse microspines with
straight walls; acute grooved spines
Absent
Sizes: small (≤25 µm), medium (N25 µm); S = sexine; N = nexine. ⁎Based on SEM measurements (av. 20.51 µm).
Actinocephalus bongardii (A. St.-Hill.) Sano, A. M. Giulietti et al. 932-
80, SPF; Actinocephalus cabralensis (Silveira) Sano, CFCR 15363, SPF;
Actinocephalus denudatus (Körn.) Sano, CFCR 2428, SPF; Actinocephalus
divaricatus (Bong.) Sano, CFCR 2258, SPF; Actinocephalus polyanthus
(Bong.) Sano, CFCR 6349, SPF; Actinocephalus ramosus (Wikstr.)
Sano, A. M. Carvalho & J. Saunders 3140, SPF.
Blastocaulon albidum Ruhland, N. Hensold 234, HUEFS; Blastocaulon
scirpeum (Mart.) Giul., CFCR, SPF 3006.
Eriocaulon elichrysoides Bong., W. Monteiro 9, HUEFS; Eriocaulon
humboldtii Kunth, Almeida & Cordeiro552, HUEFS; Eriocaulon ligulatum
(Vell.) L. B. Sm., CFCR 1522, SPF; Eriocaulon sellowianum Kunth,
Farias et al. 97/127, HUEFS.
Lachnocaulon engleri Ruhland, Unwin 237, MU; Lachnocaulon
minus Small, Unwin 230, MU.
Leiothrix angustifolia (Körn.) Ruhland, CFCR 1427, SPF; Leiothrix
distichoclada Herzog, W. Ganev 1964, HUEFS; Leiothrix flavescens (Bong.)