María C. Tellería

Eocene Patagonia Fossils of the Daisy Family

Fossil evidence suggests that daisies and sunflowers may have originated in South America more than 47 million years ago. Fossil capitula and pollen grains of Asteraceae from the Eocene of Patagonia, southern Argentina, exhibit morphological features recognized today in taxa, such as Mutisioideae and Carduoideae, that are phylogenetically close to the root of the asteracean tree. This fossil supports the hypothesis of a South American origin of Asteraceae and an Eocene age of divergence and suggests that an ancestral stock of Asteraceae may have formed part of a geoflora developed in southern Gondwana before the establishment of effective dispersal barriers within this landmass.

An extinct Eocene taxon of the daisy family (Asteraceae): evolutionary, ecological and biogeographical implications

BACKGROUND AND AIMSnMorphological, molecular and biogeographical information bearing on early evolution of the sunflower alliance of families suggests that the clade containing the extant daisy family (Asteraceae) differentiated in South America during the Eocene, although palaeontological studies on this continent failed to reveal conclusive support for this hypothesis. Here we describe in detail Raiguenrayun cura gen. & sp. nov., an exceptionally well preserved capitulescence of Asteraceae recovered from Eocene deposits of northwestern Patagonia, Argentina.nnnMETHODSnThe fossil was collected from the 47·5 million-year-old Huitrera Formation at the Estancia Don Hipólito locality, Río Negro Province, Argentina.nnnKEY RESULTSnThe arrangement of the capitula in a cymose capitulescence, the many-flowered capitula with multiseriate-imbricate involucral bracts and the pappus-like structures indicate a close morphological relationship with Asteraceae. Raiguenrayun cura and the associated pollen Mutisiapollis telleriae do not match exactly any living member of the family, and clearly represent extinct taxa. They share a mosaic of morphological features today recognized in taxa phylogenetically close to the root of Asteraceae, such as Stifftieae, Wunderlichioideae and Gochnatieae (Mutisioideae sensu lato) and Dicomeae and Oldenburgieae (Carduoideae), today endemic to or mainly distributed in South America and Africa, respectively.nnnCONCLUSIONSnThis is the first fossil genus of Asteraceae based on an outstandingly preserved capitulescence that might represent the ancestor of Mutisioideae-Carduoideae. It might have evolved in southern South America some time during the early Palaeogene and subsequently entered Africa, before the biogeographical isolation of these continents became much more pronounced. The new fossil represents the first reliable point for calibration, favouring an earlier date to the split between Barnadesioideae and the rest of Asteraceae than previously thought, which can be traced back at least 47·5 million years. This is the oldest well dated member of Asteraceae and perhaps the earliest indirect evidence for bird pollination in the family.

Pollen morphology of the subfamily Barnadesioideae (Asteraceae) and its phylogenetic and taxonomic significance

Abstract The pollen morphology of 59 species of the genera Arnaldoa, Barnadesia, Chuquiraga, Dasyphyllum, Doniophyton, Duseniella, Fulcaldea, Huarpea and Schlechtendalia belonging to the Barnadesioideae has been studied with light and scanning electron microscopy. Three main pollen types were recognized: (1) lophate pollen found in Barnadesia and Huarpea ; (2) pollen with intercolpal depressions in Arnaldoa and some species of Dasyphyllum (subtypes I, II and III) and Schlechtendalia ; and (3) pollen without depressions found in Chuquiraga, Dasyphyllum p.p., Doniophyton, Duseniella and Fulcaldea . In Dasyphyllum cryptocephalum and D. tricophyllum , we recognized a new type with 21–23 depressions. A key for the identification of pollen types is presented. Phylogenetic significance of the three palynological characters (morphology, sculpture and structure) is interpreted through phylogenies of Barnadesioideae proposed by earlier workers. Cladograms show the monophyletic group Barnadesia–Huarpea supported by a smooth exine and lophate pollen. Our results show that the 1-layered exine represents a synapomorphy for Dasyphyllum, Arnaldoa, Fulcaldea, Barnadesia and the Huarpea group.

Floral resources foraged by Geotrigona argentina (Apidae, Meliponini) in the Argentine Dry Chaco forest

Abstract This study is the first contribution to knowledge of the relationships between Geotrigona argentina and the plants of the Argentine Dry Chaco forest. A total of 1260 g of honey (corresponding to 146 pots) and 763 g of pollen (63 pots) stored in four underground nests was studied. The honey pots from each nest were homogenised and the four honey samples were analysed by melissopalynological methods, whereas the pollen pots were studied individually. Both classical counts and counts affected by the volume of the pollen types were carried out. Pollen data were statistically analysed. Additional data on both protein and lipid content is also provided. A total of 39 pollen taxa were identified. Pollen collection was focused on a few pollen taxa: Prosopis, Castela coccinea, Maytenus and Capparis; these taxa, together with Ziziphus mistol and Pisonia zapallo, were also important nectar sources. The preliminary results show that pollen collection varied seasonally, being most diverse in the summer when G. argentina incorporates herbaceous plants into its diet. The pollen collection spectrum of G. argentina is similar to that of other Trigonina bees in that the main plant species collected are a few large shrubs or trees, whose flowering consists of small and clustered flowers. Pots with large amounts of monofloral loads with pollen from only a few species suggests an organised foraging behaviour that includes the recruitment of foragers, such as that observed in other eusocial bees.

Plant Resources Foraged by Polybia Scutellaris (Hym. Vespidae) in the Argentine Pampas

Abstract The plants foraged by Polybia scutellaris were studied by analysing the pollen of honey collected from six nests. 34 morphological types were identified. These honeys showed a predominance of Poaceae and Cyperaceae pollen. The main access to anemophilous pollen is through the honeydew produced by Claviceps in Paspalum dilatatum. The principal sources of nectar were the native “Astereae” (Aster squamatus, Baccharis sp. and Solidago chilensis) and Eucalyptus sp. When collecting honeydew and nectar, wasps foraged plants close to their nest. Most of the plants visited belonged to a dense population. The successive flowering reflected in these honeys, shows that wasps also consume honey in summer and that it is not all stored for the winter season.

Pollen harvest by solitary bees (Ptilothrix relata, Hym. Apidae, Emphorini) in the Argentine pampas – preliminary results

In order to determine the plants foraged by solitary Ptilothrix relata, the pollen content of food provisions was identified. The main pollen types confirm foraging by these bees on Malvaceae, Asteraceae and Onagraceae. Pollen sources belonging to Cucurbitaceae, Dipsacaceae and Portulacaceae families enrich the harvesting range of P. relata. According to the preliminary results, these bees can be considered more as narrowly polylectic than oligolectic because they collect pollen from a few unrelated species. Among the most abundant pollen collected, two major morphological types were recognized: (1) pollen with long spines (4–25u2005μm), many single apertures and large size (115–135u2005μm of diameter); and (2) tricolporate pollen with viscin threads.

Palynological analysis of food reserves found in a nest of Bombus atratus (Hym. Apidae)

The pollen present in food reserves, pollen masses and honey, stored in an aerial nest of Bombus atratus was investigated. Field observations were also made. 23 pollen morphological types, belonging to 16 families of plants, were identified. The principal sources of nectar were: Eucalyptus spp., Aptenia cordifolia, Lagerstroemia indica and Salvia microphylla. While Solarium spp. and Liliaceae, were the main sources of pollen. These analyses of pollen reserves and honey, coupled with field observations, allow a reconstruction of the wide foraging spectrum of Bombus atratus.

Intraspecific variation in the pollen exine sculpture of Jaborosa runcinata Lam. (Solanaceae)

The variability of ectexine sculpture in the pollen of Jaborosa runcinata (Solanaceae) was studied with light and scanning electron microscopy. Three main ectexine variants are recognized: incomplete reticulate, a combination of incomplete reticulate and gemmate‐granular, and gemmate‐granular. A range of transient conditions were also noted between the two extremes. Apertures vary from a basically triporate‐aspidate arrangement to pollen grains which appear to have a rudimentary colpus. The sculptural variability of the ectexine, and a tendency towards a colpus, in J. runcinata are interesting as intraspecific variation does not appear to be common within Solanaceae.

Palynological survey of the subtribe Elephantopinae (Asteraceae, Vernonieae)

Despite the taxonomic value of pollen morphology within the tribe Vernonieae, a detailed study of the pollen of the subtribe Elephantopinae is still lacking. The pollen morphology of ten species, representing three of the four genera of the subtribe, Elephantopus, Pseudoelephantopus and Orthopappus, was studied with LM, SEM, and TEM. The pollen of all the species studied was found to be echinolophate, although the differences in aperture features and both sculpture and exine structure allowed recognizing two pollen types. The species of Elephantopus (except for E. elongatus) and Pseudoelephantopus share the regular or more or less regular ridges pattern, the colporate condition but with the ectoapertures little developed, and the acaveate exine structure. From the sculpture and the apertures, the pollen of Caatinganthus harleyi was found to be similar to that of Elephantopus and Pseudoelephantopus. The pollen morphology of the monotypic Orthopappus, which is shared with that of E. elongatus, was further investigated for the first time. We found that it differs from that of the other species in having an irregular pattern of ridges, colporate condition but with a well-developed ectoapertures, and caveate exine. Additional studies of the exine structure and apertures features, coupled with molecular phylogeny, are needed to understand the evolution of pollen characters and re-evaluate the intergeneric relationships within the tribe.