Pelodryadidae

Pelodryadidae

Tyler (1979:73) eloquently compared faunal relations between Africa and South America and those between that continent and Australia: “South America and Africa may be regarded as lovers who experienced and exploited a large zone of contact and had considerable opportunity for interchange and exchange across it. In contrast, the South American-Australian relationship suffered from being in the form of an arranged engagement of longer duration. The couple never so much as touched one another at any time. The only contact was via a related intermediary named Aunt Arctica, whose presence between them effectively prevented a comparable degree of intimacy, and who is now outwardly cool and distinctly secretive about revealing what took place between them.” So be it.

Although Hyla meridionalis now occurs in Mediterranean northwestern Africa, there is no evidence that hylid frogs ever existed in sub-Saharan Africa. These frogs originated in South America and dispersed from there to Australia and to North America. Ancestral Hylidae diverged from the phyllomedusid-pelodryadid clade in the Paleocene 61.8 (57.5–66.1) Mya. The hylid clade retained the ancestral chromosome complement of 2n = 24, whereas the number changed to 2n = 26 in the phyllomedusid-pelodryadid clade. Following the split of pelodryadid and phyllomedusid frogs at 52.5 (47.6–57.4) Mya, the initial divergence (crown node) of pelodryadid frogs occurred in the mid-Eocene 44.2 (40.1–48.3) Mya and that of phyllomedusid frogs was later, 33.3 (29.0–37.6) Mya. When South America separated from Antarctica 35.0–30.5 Mya, ancestral pelodryadid frogs were present on that continent and Australia before the latter separated from Antarctica 35.5 Mya (Fig. 18). Our analysis suggests that the differentiation of what are now Pelodryadinae and Pelobiinae occurred in the mid-Eocene and that the genera of pelodryadids differentiated (crown nodes) in the late Eocene and Oligocene: Nyctimystes 35.1 (29.3–40.8), Litoria 33.8 (28.9–38.7), Dryopsophus 29.5 (26.0–33.1) Mya.

Four major clades of Litoria already existed by the early Oligocene (31 Mya). Our limited taxon sampling of New Guinean Litoria precludes determination of possible centers of diversification in New Guinea and Australia; likewise, we have no genomic data that might indicate monophyly of the stream-breeding Litoria in Queensland. After its diversification from the clade leading to Dryopsophus, Nyctimystes was restricted to the humid northern part of Australia, which together with the collision of the plates and major uplifts in the Miocene, became New Guinea. Most species of Nyctimystes differentiated in the early to mid-Miocene (10–22 Mya). Some major clades of Dryopsophus originated in the mid- to late Oligocene (24–26 Mya). The clade containing the terrestrial species of Dryopsophus (formerly placed in the genus Cyclorana) inhabiting xeric to subhumid regions of Australia diverged in mid-Miocene times—13.4 (8.0–18.8) Mya, the time of major aridification in central and southern Australia.