title: Subterranean ants: the case of Aphaenogaster cardenai (Hymenoptera: Formicidae).
abstract: Recently, a series of systematized studies of the Milieu Souterrain Superficiel (MSS) are being carried in several enclaves of the Iberian Peninsula, which have entailed the finding of the enigmatic ant Aphaenogaster cardenai Espadaler, 1981, hitherto considered as hypogean, in a mountain range far away from its known distribution area. Its ecological role and its possible area of distribution are discussed due to this finding, as well as its known morphology, distribution, habitat use, flight ability of the sexual forms, and moment of activity. This enabled reviewing and discussing the actual knowledge on the possible adaptations and exaptations of the Formicidae to the subterranean environments in wide sense and concretely to the MSS. According to all above, ants might adapt to the deepest hypogean environments by means of changes in their social structure, but without those changes, the MSS would be their last frontier in their process of colonization of hypogean environments.
authors.affiliation: Departamento de Ciencias de la Vida, Facultad de Biología, Ciencias Ambientales y Química, Universidad de Alcalá, E-28871, Alcalá de Henares, Madrid, Spain vicente.ortuno@uah.es.
authors.forename: Vicente M
authors.initials: VM
authors.lastname: Ortuño
authors.affiliation: Departamento de Ciencias de la Vida, Facultad de Biología, Ciencias Ambientales y Química, Universidad de Alcalá, E-28871, Alcalá de Henares, Madrid, Spain.
authors.forename: José D
authors.initials: JD
authors.lastname: Gilgado
authors.affiliation: Departamento de Zoología, Facultad de Ciencias, Universidad de Granada, E-18071, Granada, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Tinaut
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001000:Ants / Q000145:classification* / Q000502:physiology*; D001522:Behavior, Animal; D017753:Ecosystem; D005426:Flight, Animal; D013030:Spain
keywords: Iberian Peninsula; hypogean ant; shallow subterranean habitat; subterranean biology