Abstract
The Australian populations of the green-eyed tree frog Litoria genimaculata consist of a northern and southern genetic lineage that meet in a mosaic contact zone comprising two independent areas of contact: one where the main ranges of the lineages overlap, and the second where a population of the southern lineage is isolated within the range of the northern lineage. A recent study failed to find significant reproductive isolation between the main ranges of the two lineages, despite deep genetic divergence, partial postzygotic isolation, and call differences. The study did, however, demonstrate rapid phenotypic divergence and speciation of the isolated population of the southern lineage from both the parapatric northern lineage and from the allopatric, but genetically similar, main range of the southern lineage. Herein, the isolated population of the southern lineage is described as a distinct species, Litoria myola sp. nov., whereas the remainder of the southern lineage and the northern lineage are retained as a single, paraphyletic species, Litoria genimaculata. Resolving this unusual systematic situation demonstrates the value of using multiple lines of evidence in delimiting species. Litoria myola sp. nov. has a very small distribution and population size and warrants a Critically Endangered listing (B1, 2) under IUCN criteria. Threats and management recommendations are outlined, and the conservation of hybrid zones as areas of evolutionary novelty is discussed.
Highlights
The green-eyed tree frog, Litoria genimaculata, occurs in tropical rainforest in north-east Australia and is widely distributed in New Guinea (Richards, McDonald & Ingram, 1993)
L. myola sp. nov. females are generally smaller than those of L. genimaculata (Table 1), there is no significant difference in size between L. myola sp. nov. and L. genimaculata where the two species co-occur in the Litoria myola sp. nov
Most stream catchments in the Kuranda area were surveyed for L. myola during this period
Summary
The green-eyed tree frog, Litoria genimaculata, occurs in tropical rainforest in north-east Australia and is widely distributed in New Guinea (Richards, McDonald & Ingram, 1993). Hoskin et al (2005) used a combination of genetic, morphological and call analyses, experimental crosses, and mate choice trials to characterize the contact zone between the northern and southern lineages of L. genimaculata and assess the degree of reproductive isolation between them. The iS population was found to have diverged significantly in male size and call from the genetically similar allopatric main range of the southern lineage and mate choice trials revealed highly significant premating isolation between iS and the remainder of its southern lineage (Hoskin et al, 2005). A NEW SPECIES OF AUSTRALIAN TREE FROG (LITORIA) 551 dentally, from the main range of the southern lineage By contrast, they concluded that speciation has not occurred at the main contact (Contact A) between the northern and southern lineages. The value of the approach used here to delimit species, that combines multiple lines of data with direct and genetic tests of reproductive isolation, is discussed
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