Detection of cryptic species of Rugopharynx (Nematoda: Strongylida) from the stomachs of Australian macropodid marsupials

Abstract

Sequences of the internal transcribed spacers of nuclear ribosomal DNA (ITS-1 and ITS-2) were determined for species of the genus Rugopharynx and Rugonema labiatum, nematodes from the stomachs of macropodid marsupials. Phylogenetic analyses of the aligned sequence data were conducted. The relationships provided molecular support for all species currently recognised, some of which are based on minor morphological differences and on multilocus enzyme electrophoretic data, but also indicated that additional, cryptic species exist within the genus. In addition, the genus Rugonema is placed as a synonym of Rugopharynx, its sole species becoming Rugopharynx labiatum n. comb. The molecular data provided some insights into the evolution of complex buccal capsule morphologies within the genus, but there was no evidence of co-evolution between the macropodid hosts and their parasites.

Keywords: Cloacininae; Cryptic species; Macropodidae; Phylogeny; Rugopharynx; Strongylida.

Graphical abstract

Fig. 1

Localities within Australia at which specimens of Rugopharynx used in this study were collected. Coordinates for each locality are provided in Table 1. 1, Lake Clifton; 2, Waroona; 3, Collie, Wellington Dam; 4, Perup River; 5, Kalgoorlie; 6, Wallerberdina Station; 7, Port Augusta; 8, Ashbourne; 9, Kangaroo Island; 10, Naracoorte; 11, Hattah Lakes National Park; 12, Yan Yean; 13, The Gurdies; 14, Launceston; 15, Emu Flat, Bondo State Forest; 16, Trangie; 17, Grafton; 18, Lamington National Park; 19, Miles; 20, Dawes; 21, Mt Sebastopol; 22, Rockhampton; 23, Winton; 24, Proserpine; 25, Bowen; 26, Magnetic Island; 27, Lake Barrine.

Fig. 2

Morphological buccal capsule types in the genus Rugopharynx. I, simple cylindrical buccal capsule, R. macropodis; IIA, bilobed buccal capsule with subequal divisions, R. epsilon; IIB, bilobed buccal capsule with anterior lobe shorter, R. rufogrisea; III, trilobed buccal capsule, R. longibursaris.

Fig. 3

Phylogenetic relationships of species of Rugopharynx and Rugonema labiatum based on a Bayesian analysis of the sequence data of the ITS+ nuclear ribosomal DNA. Values above branches indicate posterior probabilities that were greater than 0.8. Abbreviations of Australian state names are provided in Table 1.

Fig. 4

Phylogenetic relationships of species of Rugopharynx and Rugonema labiatum based on a neighbor-joining analysis of the sequence data of the ITS+ nuclear ribosomal DNA. Values above and below branches represent the NJ and MP bootstrap values (respectively) that were greater than 70%.

Fig. 5

Molecular phylogeny of species of Rugopharynx and Rugonema labiatum based on a consensus of the BI, NJ and MP trees (Fig. 3, Fig. 4), and the relationships of their hosts. This figure includes species of Macropus (M. agilis, M. antilopinus, M. bernardus) which are not hosts to species of Rugopharynx, as well as M. parma, from which no material could be obtained for genetic studies. Only those species of Petrogale included in this study are shown on the host tree. The morphology of the buccal capsule for each nematode taxon is also shown.