N. Pérez Hidalgo

Pistacia terebinthus L. leaflets: an anatomical study

SummaryThe present work describes the structural characterization of Pistacia terebinthus leaflets, focusing on changes in structure during the maturation process. P. terebinthus leaflets are characterized by the presence of: (1) abundant crystals, mainly in mesophyll cells; (2) both unicellular and glandular tri- chomes; (3) a large amount of tannins; (4) a simple epidermis covered by a thick, wrinkled cuticle; (5) anomocytic stomata lined by cuticle with an amphistomatic distribution; (6) a densely packed mesophyll, which becomes thicker as the leaflets mature; (7) a very prominent palisade parenchyma; (8) a midvein and larger secondary veins, each encircled by a sclerenchymatic sheath; (9) schizogenic ducts in the phloem tissue; (10) a leaflet margin slightly curved towards the abaxial side. As a whole, P. terebinthus leaflets show sclerophytic morphology. During leaflet maturation, the following major morphological changes were noted: (1) trichomes become scarcer, (2) the cuticle gained in thickness, (3) crystal inclusions were more abundant and (4) the mesophyll developed large intercellular spaces.

Evaluating the importance of trophobiosis in a Mediterranean ant community: a stable isotope analysis

Trophobiosis between aphids (Aphididae, Hemiptera) and ants (Formicidae, Hymenoptera) is considered to provide an important source of nutrition for ants by aphid honeydew and aphids themselves used as prey. However, little is known about nutrient fluxes and the relative importance of trophobiosis for different ant species. Combining direct contact observations between ants and aphids with stable isotope analyses of distinct multitrophic sample sets (soil, plant, aphid, and ant), we aimed at disentangling the importance of trophobiosis in a Mediterranean food web and possible feedbacks on the functional diversity of ants in a species-rich organic Citrus plantation. We analyzed δ13C- and δ15N-values of sample sets for fertilized and natural soil, using the fertilizer as natural isotope label. The results showed trophic relationships between 18 host plant species, 22 aphid species, and 7 ant species. Direct observation revealed at least 40 different plant–aphid combinations and 25 aphid–ant combinations with a marked range of δ15N-values. However, the δ13C and δ15N isotope ratios still reflected the trophic levels. A significant correlation occurred between the isotope ratios of aphids and their host plants. However, no relationship was found between aphids and ants or between plants and ants revealing that many ant species do not exhibit a close relationship with their trophobiotic partners. Isotopic data allowed us to separate ant species into trophic functional groups and showed the relevance of other food resources. The applied fertilizer shifted the isotopic baseline for the whole trophic system. By combining the stable isotope analysis with the exact origin of the samples, we avoided a misleading interpretation of the high isotopic range of species. Thus, we emphasize the importance of considering a baseline in stable isotope food web studies.

A New Genus and Species of Asteraceae-Inhabiting Aphid (Hemiptera: Aphididae) from Costa Rica and Mexico

ABSTRACT Ucrimyzus villalobosi Mier Durante & Pérez Hidalgo gen. n., sp. n. (Hemiptera: Aphididae: Macrosiphini) are described from apterous and alate viviparous females collected on species of genera Bidens, Schkuhria, Senecio and Stevia (Asteraceae: Asteroideae) in Costa Rica and Mexico. Principal components analysis (PCA) was done to verify that the studied aphids belong to a single species regardless of their geographical origin or host plant. Molecular analyses were carried out on the sequences of a fragment of the mitochondrial gene encoding for cytochrome c oxidase subunit 1 (COI) and of a fragment of the nuclear gene encoding elongation factor 1&agr; (EF1&agr;). The taxonomic discussion takes into account the conclusions of the molecular analyses and the morphologic study compared with other genera of Macrosiphini. The identification keys by Blackman & Eastop (2006) to aphids living on each mentioned plant genus are modified to include the new species.