Distribution and biology of the extant Microbiotheria (Dromiciops gliroides) in Southern Patagonia (Argentina) and views of their evolutionary origin and possible links to Australia.

GUROVICH, YAMILA

Sydney

Simposio; Riversleigh Symposium 2016; 2016

UNSW

Dromiciops gliroides (Order Microbotheria, Australidelphia) is a small extant nocturnal marsupial that lives in temperate forests of Southern Patagonia (Argentina and Chile) and whose southern most limits in Argentina are Parque Nacional Los Alerces, Chubut (42°50′ 40.3″S; 71°50 ′17.4″W) and the Island of Chiloe (Chile 43°21″S). Dromiciops is considered more closely related to Australasian marsupials than to South American ones and can undergo short periods of daily topor and is the only South American marsupial that can undergo long periods of hibernation (between 1- 3 weeks).Until recently it was thought that D. gliroides was the only living species of Microbiotheria but in 2016, two other species, D. bozinovici (Chile, Neuquen, Argentina) and D. mondaca (Chile) were discovered based on morphological variation from museum specimens and distribution of these specimens. D. gliroides is the southern most species of the three, and the fact that Dromiciops is not a monospecic genus, now poses new questions regarding the evolutionary history of the genus (e.g., the historical biogeography of the genus and the recent demographic history of each species). What still also remain unanswered are the unresolved phylogenetic relationships between Dromiciops and other marsupial clades as well as the biogeographical question of how and when marsupials arrived to Australia and were able to diversify in such a great fashion in what is known today as Riversleigh. In Australia, no microbiotherians are known from Riversleigh however all other major Australian orders are known from that time, with the timing of these major groups interpreted to have occurred prior in the Eocene and Paleocene. There is however, possible microbiotherian fossils reported from the older Early Eocene Tingamarra Local fauna in northeastern Australia. In South America and Antarctica, Microbiotherians are known from the Cenozoic based on fossil teeth, and the oldest unequivocal South American australidephian is known from the early Miocene of Santa Cruz. In order to try to solve these phylogenetic relationships using molecular and morphological data more studies on morphology are need using extant species. Here I present morphological descriptions and the external anatomy such as pouch morphology, external newborn young morphology of the living Dromiciops gliroides from Argentina which can be used in the future for more thorough phylogenetic relationships to establish relationships between Dromiciops and other marsupial clades.