The Syphaciinae (Oxyuridae, Nematoda) parasitic in rodents and lagomorpha. Numerical taxonomy. Cladistic analysis of evolution

Phylogeny and biogeography of species of Syphacia Seurat, 1916 (Nemata : Oxyurida : Oxyuridae) from the Australian Bioregion

Pinworm nematodes of the genus Syphacia (Nemata : Oxyurida : Oxyuridae) have a global distribution, and infect the caecum of rodents. Within the Australian Bioregion, 17 species of Syphacia infect a range of rodent hosts. Pinworms are traditionally thought to have coevolutionary relationships with their hosts, but the evolution and dispersal of Australian rodents and their helminths remains unclear. This combination of factors allowed us to investigate the likely relationships of Australian Syphacia species based on phylogenetic analysis, overlaid with the ecology and relationships of host species. We conducted a phylogenetic analysis using morphological characters of the species of Syphacia from the Australian Bioregion in order to examine the relationships between species, and to investigate how host evolution and phylogeny could inform (or be informed) by parasite phylogeny. Application of the taxon pulse theory of parasite speciation by matching host species to parasites shed some light on the timing of speciation of rodent hosts. We found that species of Syphacia had reasonably close host–parasite relationships, with additional evidence for ecological fitting or host switching occurring. Evidence provided here suggests strongly that most elements of the Stockholm Paradigm are at play in structuring the relationships we observe in this pinworm–mammal system.

A new species of Syphacia (Seuratoxyuris) (Nematoda: Oxyuridae) from Sooretamys angouya Fischer, 1814 (Rodentia: Cricetidae) in Argentina

Syphacia (Seuratoxyuris) hugoti n. sp. (Nematoda: Oxyuridae) is described from the cecum of Sooretamys angouya (Cricetidae: Sigmodontinae: Oryzomyini) captured in Formosa Province, Argentina. The diagnosis of the subgenus is emended, and the new species is separated from eight congeners by the distribution of submedian papillae and amphids, shape of the cephalic plate, presence of deirids, absence of cervical and lateral alae, length of the spicule, structure of the accessory hook of the gubernaculum and distance of excretory pore and vulva from the anterior extremity. The analysis suggests that S. (Se.) oryzomyos should be removed from Seuratoxyuris and redesignated as S. (Syphacia) oryzomyos n. comb. To date, of the species of Syphacia found in South and North American, 7 parasitize Oryzomyini rodents, of which two are distributed in Argentina. The present study constitutes the first record of the subgenus Seuratoxyuris from Argentina and the third record of a Syphacia species from rodents of the tribe Oryzomyini.

A new species of Syphacia (Nematoda: Oxyuridae) from Oligoryzomys nigripes (Rodentia: Cricetidae) in Argentina

The aim of this paper is to describe Syphacia kinsellai n. sp. (Nematoda: Oxyuridae) from the cecum of Oligoryzomys nigripes (Olfers 1818) (Sigmodontinae: Oryzomyini) captured in Misiones Province, Argentina. The new species can be differentiated from other species of the genus principally by the shape of the cephalic plate; distribution of submedian papillae and amphids; development of porous badge; presence of derids in females; absence of cervical and lateral alae; shape and structure of accessory hook of gubernaculum; and distance of excretory pore and vulva from the anterior extremity. Until the present, only two species of Syphacia had been reported from Argentina in sigmodontine rodents, the first one parasitizes an Oryzomyini host and the second one an Akodontini host. This new species is the second record of Syphacia from the tribe Oryzomyini in Argentina; however, we propose that the first record, S. oryzomae, should be treated as a nomen dubium.