Abstract Lichens are symbiotic organisms, usually composed of a fungal partner, the mycobiont, and one or more photosynthetic partners, the photobiont, which is most often either a green alga or a cyanobacterium, that harbor a diverse community of invertebrates such as rotifers, tardigrades, mites, springtails, crustaceans, and nematodes. In this work, we isolated the nematode Geraldius galapagoensis (Chambersiellidae) associated with the lichen Hyperphyscia syncolla (Physciaceae) in a region of Buenos Aires Province, Argentina. This species was discovered in a tropical forest of Ecuador and is characterized mainly by a head offset by a constriction from the rest of the body, a esophagus with a cylindrical pharyngeal corpus without a median bulb, a narrow isthmus and an oval basal pharyngeal bulb with strong transverse/butterfly valve apparatus, a tail curved ventrally, ending in dorsally hooked end; the male with seven pairs of latero-ventral pre-anal papillae and three pairs of post-anal in the following positions: one pair latero-ventral and two pairs dorso-lateral and two slightly curved spicules with asymmetric manubrium with an anterior extension. The comparison of the morphometrics of our G. galapagoensis male with that of the original description shows that the body length is shorter, as are the distance of the excretory pore to the anterior end and the tail. On the other hand, the distance from the anterior end to the nerve ring and the esophagus length are greater. The head width, body diameter and spicule length are quite similar. We provide a morphological and morphometrical characterization of a G. galapagoensis second isolate and the first world report of molecular sequences belonging to this species. organisms partner mycobiont partners photobiont cyanobacterium rotifers tardigrades mites springtails crustaceans nematodes work Chambersiellidae (Chambersiellidae Physciaceae (Physciaceae Province Argentina transversebutterfly transverse butterfly apparatus ventrally lateroventral latero ventral preanal pre anal postanal post positions dorsolateral dorso lateral extension G shorter hand greater width similar

Abstract Caenorhabditis elegans is a free-living nematode, belonging to the bacterivorous trophic group. Although it was cited in several countries, in different types of ecosystems and in associations with other organisms, the wild habitats of this nematode have not yet been precisely defined. In Argentina, C. elegans was recently isolated from the hoverfly Allograpta exotica, a voracious predator with potential biological control against aphids in horticultural crops. In this frame, the objectives of this study were (i) to characterize it molecularly and morphologically (ii) to report a wild strain of C. elegans for the first time from Argentina, (iii) to present a new ecological niche by associating it with A. exotica and (iv) to evaluate the pathogenicity against these insects. The results of the morphological and molecular analyses made it possible to determine that the isolated nematode was C. elegans, thus establishing the ARGLP1900 wild strain as the first record of this nematode for Argentina. A new association was described, since there are no records of interaction between C. elegans and A. exotica, providing information on a new ecological niche. The new wild strain found in this work, could be appropriate for comparative genomic studies with other C. elegans strains.

Diploscapter coronata is a free-living soil bacterial-feeding nematode found in compost, sewage or agricultural soil and as a facultative parasite of insects and vertebrates, even humans. The clinical symptoms include epigastric tenderness, diarrhea, crampy abdominal pain, weakness and nauseas. Also, they have been considered as potential carriers of bacteria pathogenic to the surface of preharvest fruits and vegetables in contact with soil. In this note, we reported the presence of D. coronata in the framework of diverse soil nematodes samplings in orchards of Abasto town, Buenos Aires province, Argentina. Soil samples taken from tomato growing (Lycopersicon esculentum) were processed in the laboratory by the centrifugation method, while collected roots were observed directly under stereomicroscope in order to isolate nematodes. Specimens were identified by morphological and morphometric characteristics. Results showed the presence of D. coronata in agricultural soil and in association with root galls, caused by the plant-parasitic nematode, Nacobbus aberrans. Females were the only isolated stage. The detection of this nematode in greenhouses where dogs, cats and poultry live together without any health control highlights the importance of applying proper hygiene measures during agricultural practices to avoid contamination of fruits and vegetables and prevent infections in domestic animals and humans. This report constitutes the first record of the Diploscapter genus with the species D. coronata in Argentina.

Diploscapter coronata es un nematodo de vida libre que habita el suelo y se alimenta de bacterias. Se ha encontrado en compost, alcantarillas o suelos agrícolas y como parásito facultativo de insectos y vertebrados, incluyendo al hombre. Los síntomas clínicos incluyen: sensibilidad epigástrica, diarrea, dolor abdominal y náuseas. Incluso, han sido considerados potenciales portadores de bacterias patogénicas asociadas con la superficie de frutas y vegetales pre-cosechadas en contacto con el suelo. En esta nota, se reporta la presencia de D. coronata en el marco de diversos muestreos de nematodos de suelo, en huertas de la localidad de Abasto, provincia de Buenos Aires, Argentina. Las muestras de suelo tomadas de cultivo de tomate (Lycopersicon esculentum) se procesaron en el laboratorio mediante el método de centrifugación, mientras que las raíces recolectadas fueron observadas directamente bajo microscopio estereoscópico con el fin de aislar los nematodos. Los especímenes fueron identificados por características morfológicas y morfométricas. Los resultados mostraron la presencia de D. coronata en suelos agrícolas y en agallas radicales causadas por el nematodo parásito de plantas Nacobbus aberrans. Las hembras fueron el único estadio aislado. La detección de este nematodo en invernaderos donde gatos, perros y aves de corral viven juntos sin ningún control sanitario, realza la importancia de adoptar medidas apropiadas de higiene durante las prácticas agrícolas para evitar la contaminación de frutas y verduras y prevenir infecciones en animales domésticos y el hombre. Este informe constituye el primer registro del género Diploscapter con la especie D. coronata en Argentina.