ANNALES ZOOLOGICI (Warszawa), 2020, 70(2): 289-304 HIGHLIGHTING THE ELUSIVE: NEW FINDINGS AND A REDESCRIPTION OF THE RARE ANT LEPTANILLA PLUTONIA LÓPEZ, MARTÍNEZ ET BARANDICA, 1994, PRESENTING MORPHOLOGICAL NOVELTIES FOR THE GENUS SERGIO PÉREZ-GONZÁLEZ1,*, JOSÉ M. GÓMEZ-DURÁN2 and M. DOLORES MARTÍNEZ-IBÁÑEZ1 1Departamento de Biodiversidad, Ecología y Evolución, Unidad Docente de Zoología y Antropología Física, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, 28040, Madrid, Spain 2Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Ctra. de La Coruña, km. 7.5, 28040 Madrid, Spain *Corresponding author: e-mail:
[email protected] Abstract.— Leptanilla Emery, 1870 includes 47 species of strictly endogean ants, distributed through Africa, Europe, Asia and Australia, characterized by many peculiarities, such as their tiny size (between 1.0–2.5 mm long), lack of pigmentation, lack of eyes and very narrow elongate bodies. Queens are apterous and dichthadiigynes. Males have wings and eyes. Their lifestyles remain virtually unknown. The Western Mediterranean region hosts a high diversity, with 9 species in north Africa and 5 in the Iberian Peninsula. Recent sampling in Central Spain (Tortuero, Guadalajara province) led to the discovery of a colony of a large-sized Leptanilla species. This population can be assigned to L. plutonia, a species known from a single worker (the holotype) until now, easily distinguished from other Iberian species by its large size. These specimens allowed for a redescription of the species, also giving the first insights into its intraspecific variability and morphological structures not mentioned in the original description, such as the presence of a secondary labrum, large apodemes in the postpetiole or a promesosternal keel, among others.