Espadaler, X. 1997c. Leptothorax caesari sp. n. (Insecta: Hymenoptera: Formicidae), a granivore with apterous males. Annalen des Naturhistorischen Museums in Wien. B, Botanik, Zoologie 99:145-150.

Espadaler, X. 1997d. Formicidos de las Sierras de Cazorla, del Pozo y Segura (Jaen, España) (Hymenoptera, Formicidae). Ecología (Madrid) 11:489-499.

Espadaler, X. 1997e. Redescription of Leptothorax schaufussi (Forel, 1879) (Hymenoptera: Formicidae). Orsis (Organismes i Sistemes) 12:101-107.

Espadaler, X.; García-Berthou, E. 1997f. Tapinoma pygmaeum (Dufour, 1857) (Hymenoptera, Formicidae), not a rare species. Orsis (Organismes i Sistemes) 12:89-92.

Espadaler, X. 1997g. Catàleg de les formigues (Hymenoptera: Formicidae) dels països catalans. Sessió d'Entomologia ICHN-SCL 9:23-42. PDF

Espadaler, X. 1998 ("1997"). [Untitled. Messor erectus Espadaler, sp. n.]. Pp. 430-431 in: Cagniant, H.; Espadaler, X. 1998 ("1997"). Le genre Messor au Maroc (Hymenoptera: Formicidae). Annales de la Société Entomologique de France (n.s.)33:419-434. PDF

Cagniant, H.; Espadaler, X. 1998 ("1997"). Le genre Messor au Maroc (Hymenoptera: Formicidae). Annales de la Société Entomologique de France (n.s.)33:419-434. PDF

Espadaler, X. 1999a. Lasius neglectus Van Loon, Boomsma & Andrásfalvy, 1990 (Hymenoptera, Formicidae), a potential pest ant in Spain. Orsis (Organismes i Sistemes) 14:43-46. PDF

Espadaler, X. 1999b. Hormigas (Hymenoptera, Formicidae) de los Monegros. Boletín de la Sociedad Entomológica Aragonesa 24:151-152. PDF

Espadaler, X.; Gómez, C. 2000. Formica dusmeti Emery, 1909, an Iberian endemic ant species: description of the male and distribution (Hymenoptera: Formicidae). Annales Zoologici (Warsaw) 50:39-41. PDF

Gómez, C.; Espadaler, X. 2000. Species body-size distributions and spatial scale in Iberian ants. Vie Milieu 50:289-295.

Espadaler, X.; Collingwood, C. A. 2001 ("2000"). Transferred ants in the Iberian peninsula (Hymenoptera, Formicidae). Nouvelle Revue d'Entomologie (n.s.)17:257-263.

Espadaler, X.; Gómez, C. 2001. Formicine ants comply with the size-grain hypothesis. Functional Ecology 15:136-139.

Espadaler, X.; Prince, A. 2001. Lasius platythorax Seifert, 1991 (Hymenoptera, Formicidae) in Spain. Orsis (Organismes i Sistemes) 16:189-192. PDF

Espadaler, X.; Roig, X. 2001 ("2000"). Ants from the Montnegre-Corredor Natural Park (NE Spain) with description of the male Lasius cinereus Seifert (Hymenoptera, Formicidae). Miscel·lània Zoològica (Barcelona) 23:45-53. PDF

Boieiro, M.; Espadaler, X.; Azedo, A. R.; Serrano, A. R. M. 2002. Four new species to the ant fauna of Portugal (Hymenoptera, Formicidae). Boletim da Sociedade Portuguesa de Entomologia 7(20):253-259.

Espadaler, X.; Akino, T.; Terayama, M. 2002 ("2001"). Taxonomic status of the ant Lasius nipponensis Forel, 1912 (Hymenoptera, Formicidae). Nouvelle Revue d'Entomologie (n.s.)18:335-341. PDF

Espadaler, X.; Espejo, F. 2002. Tapinoma melanocephalum (Fabricius, 1793), a new exotic ant in Spain (Hymenoptera, Formicidae). Orsis (Organismes i Sistemes) 17:101-104.

Espadaler, X.; Gómez, C. 2002. The species body-size distribution in Iberian ants is parameter independent. Vie Milieu 52:103-107. PDF

Buschinger, A.; Schlick-Steiner, B. C.; Steiner, F. M.; Espadaler, X. 2003. On the geographic distribution of queen polymorphism in Myrmecina graminicola (Hymenoptera: Formicidae). Myrmecologische Nachrichten 5:37-41.

Espadaler, X.; Bernal, V. 2003. Exotic ants in the Canary Islands (Hymenoptera, Formicidae). Vieraea 31:1-7.

Espadaler, X.; Gómez, C. 2003. The Argentine ant, Linepithema humile, in the Iberian peninsula. Sociobiology 42:187-192.

Steiner, F. M.; Schlick-Steiner, B. C.; Schödl, S.; Espadaler, X.; Seifert, B.; Christian, E.; Stauffer, C. 2004. Phylogeny and bionomics of Lasius austriacus (Hymenoptera, Formicidae). Insectes Sociaux 51:24-29.

Wetterer, J. K.; Espadaler, X.; Wetterer, A. L.; Cabral, S. G. M. 2004. Native and exotic ants of the Azores (Hymenoptera: Formicidae). Sociobiology 44:1-20.

Espadaler, X.; Zabalegui, I.; Calvo Sánchez, F. 2004. Primer registro de Myrmica karavajevi (Arnoldi, 1930) en la Península Ibérica (Hymenoptera: Formicidae). Heteropterus Revista de Entomologia 4:81-83. PDF

Arthofer, W.; Schlick-Steiner, B. C.; Steiner, F. M.; Konrad, H.; Espadaler, X.; Stauffer, C. 2005. Isolation of polymorphic microsatellite loci for the study of habitat fragmentation in the harvester ant Messor structor. Conservation Genetics 6:859-861. PDF

Gómez, K.; Espadaler, X. 2005. Description of the queen caste in Messor marocanus Santschi, 1927 (Hymenoptera: Formicidae). Myrmecologische Nachrichten 7:25-29. PDF

Reyes, J.; Espadaler, X. 2005. Tres nuevas especies foráneas de hormigas para la Península Ibérica (Hymenoptera, Formicidae). Boletín de la Sociedad Entomológica Aragonesa 36:263-265. PDF

Wetterer, J. K.; Espadaler, X.; Wetterer, A. L.; Aguin-Pombo, D.; Franquinho-Aguiar, A. M. 2006. Long-term impact of exotic ants on the native ants of Madeira. Ecological Entomology 31:358-368. PDF

Gómez, K.; Espadaler, X. 2006. Exotic ants (Hymenoptera: Formicidae) in the Balearic Islands. Myrmecologische Nachrichten 8:225-233. PDF