DOI: 10.2478/s11686-013-0117-y © W. Stefan´ski Institute of Parasitology, PAS Acta Parasitologica, 2013, 58(1), 105–111; ISSN 1230-2821 A new genus of the family Hymenolepididae (Cestoda) from Sephanoides sephaniodes (Apodiformes, Trochilidae) in Northern Patagonia (Chile) Vincent C. Widmer, Boyko B. Georgiev and Jean Mariaux* Vincent C. Widmer, Jean Mariaux, Department of Invertebrates, Natural History Museum Geneva, PO Box 6434, 1211 Geneva 6, Switzerland; Boyko B. Georgiev, Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113 Sofia, Bulgaria; Vincent C. Widmer, Faculty of Sciences, Department of Genetics and Evolution, Geneva University, 30, quai Ernest-Ansermet, 1211 Geneva 4, Switzerland Abstract A new species of hymenolepidid cestodes from Sephanoides sephaniodes (Trochilidae) found in Chile is described. The most characteristic features of Colibrilepis pusilla gen. nov., sp. nov. are the lack of rostellum, a cirrus sac with a thick-walled dis- tal end (separated by a constriction) and protruding into genital atrium, a thick-walled saccular uterus filling entire median field of the gravid proglottis and the small number of eggs containing thick walled embryophores with polar swellings. Staphylepis is the most similar genus but differs in its apical structure because of the presence of a rudimentary rostellum. Moreover, mo- lecular phylogenetic analyses show that Staphylepis and Colibrilepis are not sister taxa. Keywords Hymenolepididae, Hymenolepidinae, Cestoda, Sephanoides sephaniodes, Chile Introduction In the frame of a large-scale survey of tapeworms biodiver- sity worldwide, a fieldtrip aimed at inventorying the diversity of avian parasites was conducted at the Huinay Scientific Field Station (HSFS) in November-December 2008. During this ex- pedition, we have discovered a new rostellum-lacking hy- menolepidid cestode in a Green-backed Firecrown, Sepha- noides sephaniodes (Lesson, 1827), a bird of the family Trochilidae (Apodiformes). We found 13 cestode specimens that could be used in this description. Materials and Methods Birds were caught with mist nets, kept in ornithological cotton bags, quickly euthanized with chloroform and dissected im- mediately after their death. The gastrointestinal tracts were re- moved through an opening in the abdomen and examined under a stereomicroscope. Cestodes were relaxed a few min- utes in water and some proglottides were preserved in 95% ethanol for molecular analysis, the rest were fixed in hot 4% formalin and preserved in 75% ethanol for identification. Samples for morphological identification were stained with alcoholic hydrochloric carmine solution and mounted on slides in Canada balsam following de Chambrier et al. (2009). Specimens were studied by light microscopy, including No- marski’s differential interference contrast. We studied also comparative materials of other similar hy- menolepidid genera. These included Amazilolepis trinidaden- sis Schmidt et Dailey, 1992, 2 paratypes, US National Parasite Collection (USNPC 818589), and Staphylepis ambilateralis Mariaux et Vaucher, 1991, holotype and paratypes (MHNG- PLAT-15997, 15998, 15999). The phylogenetic relationship of our new material with 6 other hymenolepidid taxa was studied on the basis of their par- tial 28S (lsrDNA) and nad1 nucleotide sequences. A parasite of mammals, Hymenolepis diminuta (Rudolphi, 1819), was used as outgroup. The dataset comprised a specimen of Staphylepis Spasskii and Oshmarin, 1954, the closest genus to Colibrilepis, as well as 4 samples of Hymenolepidinae from Passeriformes belonging to Passerilepis Spasskii et Spas- *Corresponding author: jean.mariaux@ville-ge.ch