The phylogenetic relationships of endemic Australasian trichostrongylin families (Nematoda: Strongylida) parasitic in marsupials and monotremes

Abstract

The phylogenetic relationships of the endemic (or largely endemic) Australasian trichostrongylin nematode families Herpetostrongylidae, Mackerrastrongylidae and Nicollinidae as well as endemic trichostrongylin nematodes currently placed in the families Trichostrongylidae and Molineidae were examined using the complete large subunit (28S) ribosomal RNA gene. The Herpetostrongylinae proved to be monophyletic. However, representatives of the Nicollinidae nested with the Herpetostrongylinae. The Mackerrastrongylidae was also a monophyletic group and included Peramelistrongylus, currently classified within the Trichostrongylidae. The Globocephaloidinae, currently considered to be a subfamily of the Herpetostrongylidae, was excluded from the family in the current analysis. Ollulanus and Libyostrongylus, included for the first time in a molecular phylogenetic analysis, were placed within the Trichostrongylidae. This study provided strong support for the Herpetostrongylidae (including within it the Nicollinidae, but excluding the Globocephaloidinae) and the Mackerrastrongylidae as monophyletic assemblages. Additional studies are required to resolve the relationships of the remaining endemic Australasian trichostrongylin genera.

Boehmiella wilsoni (Nematoda, Heligmosomoidea, Boehmiellidae fam. nov.), found in Amazonian rodents

“…Moreover, the results of our molecular phylogenies indicated that the genus Boehmiella belongs to a family distinct from the Australasian trichostrongylins of the families Herpetostrongylidae that are known from Australian marsupials and reptiles in Australia and south-east Asia, and Nicollinidae which occurs in monotremes. Chilton et al (2015) demonstrated for the first time the close phylogenetic relatedness between Herpetostrongylinae and Nicollinidae, a result also found in our analyses. However, Boehmiella does have a number of morphological traits that are found in herpetostrongylids and nicollinids, such as the robust esophageal neodont, and the complex spicules and reduced dorsal lobe in the caudal bursa, which we interpret as simplesiomorphic characters shared by the Boehmiellidae fam.…”

Cathepsin F of Teladorsagia circumcincta is a recently evolved cysteine protease

“…The earliest bovids appeared 20 mya, 3 and since T. circumcincta is seen in sheep and goats but not cattle, we can safely assume their divergence from related nematode species occurred following or alongside bovid divergence. Chilton et al 47 – 49 have shown the evolutionary relationships between T. circumcincta (sheep and goats), O. ostertagi (cattle), and H. contortus (sheep and goats), and that they are very closely related. There was no similar protein detected in this study between T. circumcincta and O. ostertagi , the more closely related of these 3 species, but there was a protein detected from H. contortus ( Table 1 ), a slightly more distant species but still within the same Trichostrongylidae clade and with the same host species.…”

Wildlife parasitology in Australia: past, present and future

“…Coevolutionary relationships between the herpetostrongyline nematodes and their marsupial hosts have been suggested based on morphological (summarised in Beveridge and Spratt 1996, fig. 8) and molecular (Chilton et al 2015) data. Basal taxa occur in dasyurid marsupials, with subsequent diversification to the peramelids and then to the diprotodontids (possums, rat-kangaroos, wallabies and kangaroos).…”

“…Evidence for some connection between the South American and Australian marsupial fauna is provided by the cestode genus Paralinstowia, which occurs in didelphid marsupials in South America and peramelid marsupials in Australia (Beveridge and Spratt 1996). Both morphological and molecular evidence suggest that the endemic nematode family Mackerrastrongylidae may have its origins in echidnas, which presumably existed on the continent before the arrival of the marsupials, but subsequently invaded dasyurid and peramelid marsupials (Chilton et al 2015). The original Australian marsupials were carnivores and therefore the presence of parasite groups primarily parasitic in herbivores can most readily be explained by the subsequent arrival of herbivores (rodents) from Asia.…”

“…Additional examples of marsupial nematodes with an Asian distribution including parasites of bats are provided by Spratt (2007). For additional parasite groups, origins are either unknown or are contested, as is the case for the nematode subfamily Herpetostrongylinae with a South American origin proposed by Humphery-Smith (1983), an Asian origin suggested by Durette-Desset (1985) and the possibility of an origin in monotremes (echidnas) indicated by molecular data (Chilton et al 2015). Thus, the origins of the Australian marsupial helminth fauna are far from settled, but pose intriguing questions in the broader canvas of host-parasite evolution.…”