干旱区生态环境知识资源中心

A combined approach was used to study the diversity, distribution and variability of the ameirid genus Nitokra in the uppermost reaches of the Carey palaeochannel, as very little is known about habitat invasions of stygofauna in general and inland dispersal of this predominantly marine genus in particular. A 70-km-long stretch of several disconnected calcrete subterranean habitats, known as Yeelirrie, has previously shown to harbour up to ten sympatric and parapatric congeners of the miraciid genus Schizopera and six allopatric congeners of the parastenocaridid genus Kinnecaris, in addition to 11 other species of copepods. The diversity of the genus Nitokra is much smaller, with only two allopatric species in the entire area. Nitokra esbe sp. nov. is a short-range endemic, recorded in a single bore in the most downstream part of Yeelirrie. In contrast, both molecular and morphological data indicate that Nitokra yeelirrie sp. nov. is widespread here, showing one of the largest distribution ranges of any subterranean copepod in Yeelirrie. Phylogenetic analysis of Nitokra populations based on the COI gene shows N. esbe as a sister clade to other Nitokra sequences, which does not exclude the possibility of an ’active upstream’ dispersal model, proposed for other copepods of marine origin here. High levels of COI sequence divergence (similar to 10 %) among specimens of N. yeelirrie collected 8 km apart suggest the potential for considerable population differentiation or restricted gene flow within an apparently single large calcrete body. A table of the most important morphological characters for all 79 valid world species of Nitokra is presented, and replacement names are provided for four junior homonyms. An overview of the conservation status of the entire Yeelirrie stygofauna was also provided.