Ana M. Arambarri

Micromorphological variability of leaf epidermis in Mesoamerican common bean (Phaseolus vulgaris, Leguminosae)

The purpose of this work was to make a detailed description of leaf epidermal characteristics among four Mesoamerican common bean (Phaseolus vulgaris L.) types, since they may play a role in plant defence against pathogens and/or drought. Therefore, we studied variability of epidermal cell number per mm2, stomatal size and number per mm2, stomatal index, and trichome density and dimensions on both the adaxial and abaxial epidermal surfaces. In all the common bean types studied, both surfaces of the leaves were devoid of wax crystalloids. Trichome density and distribution differed among the common bean types. Furthermore, the abaxial leaf surface always presented more trichomes than the adaxial surface. The leaves were amphistomatic, with the guard cells located in line with epidermal cells. Common bean leaves presented paracytic, anomocytic and anisocytic stomatal types. All common beans presented the adaxial epidermis of the leaves with a lower density of bigger stomates than on the abaxial epidermis. Our results demonstrate that micromorphological characteristics on both leaf surfaces are variable traits among common bean types.

Taxonomy of the New World species of Lotus (Leguminosae: Loteae)

The aims of the present study were to elucidate the relationships of the New World Lotus species groups, subgenera Acmispon Raf. (sections Microlotus Benth. and Simpeteria Ottley), Hosackia Benth. and Syrmatium Vog., and to compare these results with previous classifications and recent morphological and molecular phylogenetic hypotheses. A numerical taxonomic study using unweighted pair-group arithmetic average clustering was performed. The phenogram was generated from 34 operational taxonomic units (OTUs) × 41 characters (four vegetative characters and the basic chromosome numbers, 16 epidermal traits and 20 reproductive characters). The epidermal microcharacters (epidermal cells, stomata, stomatal index and trichomes) are described and summarised for 18 species of Hosackia and Syrmatium, and the remaining characters were derived from the literature. Phenetic results resolved four groups of species which coincide with the new genera Acmispon, Hosackia Douglas ex Benth., Ottleya D.D.Sokoloff and Syrmatium proposed, having taken into consideration the most recent morphological and phylogenetic hypotheses.

Seeds in the Diet of the White-rumped Sandpiper in Argentina

Abstract The White-rumped Sandpiper (Calidris fuscicollis) breeds in Alaska and Canada, and during the nonbreeding season migrates to South America. The reported diet of this sandpiper is principally invertebrates; seeds are a very rare item. This species was studied at Guamini Pond, Buenos Aires Province, Argentina, in December 1997. The stomach contents of 23 adults were investigated. The analysis showed that during the sampling period the only food eaten by the White-rumped Sandpiper were seeds. Them were represented by the following families: Caryophylaceae, Chenopodiaceae, Fabaceae, Malvaceae, Polygonaceae, Ulmaceae, Cyperaceae and Poaceae. The seeds ranged between 0.83 and 2.25 mm in length. Stones and fragments of algae were found in all samples, the algae possibly ingested accidentally during feeding. Our findings indicate that the White-rumped Sandpiper forages on different items depending on the area, season and availability, and may be an opportunistic feeder.—The White-rumped Sandpiper ( Calidris fuscicollis ) breeds in Alaska and Canada, and during the nonbreeding season migrates to South America. The reported diet of this sandpiper is principally invertebrates; seeds are a very rare item. This species was studied at Guaminí Pond, Buenos Aires Province, Argentina, in December 1997. The stomach contents of 23 adults were investigated. The analysis showed that during the sampling period the only food eaten by the White-rumped Sandpiper were seeds. Them were represented by the following families: Caryophylaceae, Chenopodiaceae, Fabaceae, Malvaceae, Polygonaceae, Ulmaceae, Cyperaceae and Poaceae. The seeds ranged between 0.83 and 2.25 mm in length. Stones and fragments of algae were found in all samples, the algae possibly ingested accidentally during feeding. Our findings indicate that the White-rumped Sandpiper forages on different items depending on the area, season and availability, and may be an opportunistic feeder. Received 25 October 2002, accepted 29 December 2002.

The origin of the bifurcating style in Asteraceae (Compositae).

BACKGROUND AND AIMS The plant family Asteraceae (Compositae) exhibits remarkable morphological variation in the styles of its members. Lack of studies on the styles of the sister families to Asteraceae, Goodeniaceae and Calyceraceae, obscures our understanding of the origin and evolution of this reproductive feature in these groups. The aim of this work was to perform a comparative study of style morphology and to discuss the relevance of important features in the evolution of Asteraceae and its sister families. METHODS The histochemistry, venation and general morphology of the styles of members of Goodeniaceae, Calyceraceae and early branching lineages of Asteraceae were analysed and put in a phylogenetic framework to discuss the relevance of style features in the evolution of these families. KEY RESULTS The location of lipophilic substances allowed differentiation of receptive from non-receptive style papillae, and the style venation in Goodeniaceae and Calyceraceae proved to be distinctive. There were several stages of style evolution from Goodeniaceae to Asteraceae involving connation and elongation of veins, development of bilobation from an initially cup-shaped style, and a redistribution of the receptive and non-receptive papillae. CONCLUSIONS These developments resulted in bifurcation in the styles of Asteraceae, with each branch face having a different function, and it is suggested here as a mechanism that promoted outcrossing, which in turn led to the great diversification in the family.

Winter diet of Great Pampa-finches Embernagra platensis in Guaminí Lagoon, Argentina

Abstract. The diet of the Great Pampa-finch includes seeds rather than insects. Our objective was to study its diet during the winter season and, whenever possible, to record differences between the sexes in diet patterns. This species was studied at Guamini Lagoon, Buenos Aires Province, Argentina. The stomach content of 38 adult birds was investigated. The analysis shows that the food eaten by E. platensis consisted of seeds (60%) (Chenopodiaceae, Asteraceae, Ciperaceae and Poaceae) and insects (39%) (Bellostomatidae, Dytiscidae, Curculionidae, Coccinelidae, Formicidae and Apidae). Males ate more insects and, overall, more items than females. These, in turn, consumed a greater amount of plants. Niche breadth values were 2.9 for males and 3.1 for females. The seeds encountered were those of plant species typically associated with the pampas.

New media for increasing sporulation and germination of Phaeoisariopsis griseola conidia

The slow growth rate of the fungus Phaeoisariopsis griseola and the availability of a homogeneous highly concentrated inoculum is an important constraint for pathogenicity or virulence studies, where plant inoculations are needed. Therefore, the purpose of this paper was to evaluate the effect of supplementing culture media with Amaranthus cruentus seed meal on fungal growth and sporulation of isolates of P. griseola belonging to the Mesoamerican and Andean groups. The amendment of PDA or V8 media with A. cruentus seed meal resulted in a considerable increase in the number of conidia and also in their capacity to germinate; this depended mostly on the stage of maturity of conidia. Mesoamerican and Andean isolates produced a different number of conidia when cultured in vitro. Furthermore, while in Mesoamerican isolates a second degree polynomial represented the relationship between number of conidia and amount of A. cruentus supplementation, in Andean isolates the relationship was linear. It seems that either one or several of the nutritional factors provided by A. cruentus contributed to the increased production of conidia and their development, resulting in faster development of the disease and an earlier appearance of symptoms. Therefore, for cultural studies, especially for inoculum production and for pathogenicity evaluations, supplementation of the media with A. cruentus seed meal proved to be a good alternative.