Distribution and habitat preferences of Galápagos ants (Hymenoptera: Formicidae) Author Herrera Léon Baert Wouter Dekoninck, Henri W. Author Causton, Charlotte E. Author Sevilla, Christian R. Author Pozo, Paola Author Hendrickx, Frederik text Belgian Journal of Entomology 2020 93 1 60 journal article 302430 10.5281/zenodo.13710313 83b9d93e-6482-4509-82e7-d477e479612b 2295-0214 13710313 2612CE09-F7FF-45CD-B52E-99F04DC2AA56 Pheidole williamsi (Wheeler, 1919) (ANTWEB: CASENT0173266). ( Map 25 ) Pheidole williamsi is possibly endemic to Galápagos ( WILSON , 2003). The first records originate from Santa Cruz Island ( WHEELER , 1919). Currently it is distributed on 25 islands and islets and often it is found in natural areas in littoral, dry and transition zones. It nests on sandy beaches ( WHEELER , 1924), under rocks below shrubs, dry trunks of C. sinensis and dry branches of B. graveolens . It has been observed foraging between litter of mangroves in the littoral zone on Isabela Island (Playa Tortuga Negra). Pheidole williamsi was also observed on rocky soils with little leaf litter, in forests of S. pedunculata , closed woodland and from arid to moist habitats represented by Tournefortia psilostachya Kunth , W. ovata , Commicarpus tuberosus (Lam.) Standl. , Acacia sp. , S. affinis , C. galapageia , O. insularis , C. leucophlyctis , P. floribunda , Z. fagara , C. scouleri , P. galapageium , Psychotria sp. , Verbena townsendii Svenss., Pennisetum sp. and Baccharis gnidiifolia Kunth. This species was also recorded in vegetation composed of sedges (like Cyperus anderssonii Boeck. ), grasses ( P. pauperum , Setaria setosa (Sw.) P. Beauv. ), herbs ( Rhynchosia minima (L.) DC.) and shrub layers represented by O. echios and M. laricifolia . Pheidole williamsi is a common visitor to baits used for monitoring rats in islets located near to the west coast of Santiago Island. On Santiago island, ants were attacked by the fungus Myrmiciniosporidium durum Hölldobler, 1933 ( ESPADALER , 1997 ). Workers of P. williamsi were identified from material collected in holds of aircrafts in Galápagos , suggesting a possible transfer of this species from Galápagos to mainland Ecuador .