Morphological and molecular characterization of Geraldius galapagoensis (Nematoda: Chambersiellidae) associated with lichens in Argentina

RUSCONI, J.M.; GARCÍA R.; SALAS A.; BALCAZAR, D.; IBÁÑEZ SHIMABUKURO, M.; ACHINELLY F.

PAPéIS AVULSOS DE ZOOLOGIA.

Universidad de São Paulo

Año: 2023 vol. 63

0031-1049

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