Zoosyst. Evol. 85 (2) 2009, 199–275 / DOI 10.1002/zoos.200900004 Diversity and disparity ‘down under’: Systematics, biogeography and reproductive modes of the ‘marsupial’ freshwater Thiaridae (Caenogastropoda, Cerithioidea) in Australia Matthias Glaubrecht*,1, Nora Brinkmann2 and Judith Pppe1 1 Museum fr Naturkunde Berlin, Department of Malacozoology, Invalidenstraße 43, 10115 Berlin, Germany 2 University of Copenhagen, Institute of Biology, Research Group for Comparative Zoology, Universitetsparken 15, 2100 Copenhagen, Denmark Abstract Received 11 May 2009 We systematically revise here the Australian taxa of the Thiaridae, a group of freshwater Accepted 15 June 2009 Cerithioidea with pantropical distribution and “marsupial” (i.e. viviparous) reproductive Published 24 September 2009 modes. On this long isolated continent, the naming of several monotypic genera and a plethora of species have clouded both the phylogenetical and biogeographical relation- ships with other thiarids, in particular in Southeast Asia, thus hampering insight into the evolution of Australian taxa and their natural history. Based on own collections during five expeditions to various regions in Australia between 2002 and 2007, the study of rele- vant type material and the comparison with (mostly shell) material from major Australian museum collections, we describe and document here the morphology (of adults and juve- niles) and radulae of all relevant thiarid taxa, discussing the taxonomical implications and nomenclatural consequences. Presenting comprehensive compilations of the occurrences for all Australian thiarid species, we document their geographical distribution (based on over 900 records) with references ranging from continent-wide to drainage-based pat- terns. We morphologically identify a total of eleven distinct species (also corroborated as distinct clades by molecular genetic data, to be reported elsewhere), of which six species are endemic to Australia, viz. “Thiara australis”, Plotiopsis balonnensis, and “Stenomela- nia” denisoniensis with wide distribution and Melasma onca, Sermyla venustula, and Ri- palania queenslandica with more restricted ranges. In contrast, Thiara amarula and Ste- nomelania cf. aspirans as well as Melanoides tuberculata, Plotia scabra, and Sermyla riqueti are widely distributed also outside Australia, in particular in the Malay Archipela- go and the Indo-West Pacific, respectively. The occurrences especially of the latter three species are discussed, concluding on quite distinct historical contingencies. Three thiarids species, viz. Stenomelania cf. aspirans, Sermyla riqueti and Plotia scabra, are recorded here for the first time for Australia. Based on a new taxonomic framework for the Thiar- idae we point out some of the pertinent problems with naming and artificial delineation Key Words of species, revealing why typology and earlier practice of splitting was misleading in case of these truly “Darwinian snails”. We also report on finding two clearly distinct vivipar- endemism ous modes in Australian thiarids, discussing their distribution in certain fluvifaunal pro- drainage division vinces and major drainage systems in concert with these reproductive features of life his- fluvifaunal provinces tory tactics. While the live-bearing T. amarula, S. cf. aspirans, and R. queenslandica, that colonization release veligers (ovo-viviparity), are found to have very restricted occurrences in rivers marine intrusion and streams in the Jardinian province of NE Queensland only, the five more widely dis- invasion tributed Australian endemics Plotiopsis balonnensis and “Stenomelania” denisoniensis as cryptic species well as “Thiara australis”, Sermyla venustula and Melasma onca in the Leichhardtian (ovo-)viviparity province all brood and release shelled juveniles (eu-viviparity). Finally, we hypothesize (eu-)viviparity on the evolutionary history and colonization of Australia by different lineages of these veliger larvae freshwater Cerithioidea. * Corresponding author, e-mail: [email protected] # 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 200 Glaubrecht,M.etal.:SystematicsofAustralianThiaridae Introduction “Earlier in the evening I had been lying on a sunny bank & was reflecting on the strange character of the Animals of the country as compared to the rest of the World. A Disbeliever in everything beyond his own reason, might exclaim, ‘Surely two distinct Creators must have been at work’”. (Charles Darwin, January 1836 at Wallerawang, New South Wales) Australia has an eminently curious and peculiar fauna as being only recent invaders from the north, as it was and flora, distinct in a multitude of ways from that in held by pre-continental drift views e.g. for birds (Mayr other parts of the world, and immediately evident to the 1944), amphibians (Darlington 1965) or other faunal first naturalists. When Charles Darwin visited the area members in particular of inland waters (Williams & Al- of Sydney and the Blue Mountains early in 1836 during len 1987). Also the tropical rainforests dominating his world spanning voyage on board the “Beagle”, northeastern Queensland and New Guinea today were known for its pivotal influence not only on his career long conceived of as unimportant appendage of forests but also on the origin of evolutionary theory, he soon in SE Asia, due to the earlier prevailing palaeobotanical recognized this “strange character” of the fauna, as it view that rather the widespread eucalypt forest of Aus- appears in the above given passage of his “Beagle” tralia was the ancestral habitat, thus also for animal di- diary (Keynes 1988; Nicholas & Nicholas 1989). versification (for discussion see e.g. White 1986, 1994; Long predicted only as “terra australis incognita” the Archer et al. 1991; Flannery 1994; Heinsohn 2008). fifth continent is historically “new” land; however, in Accordingly, it remained the standard scenario that this fact this strange dry land with its weird and wonderful long isolated continent certainly must have been colo- assortment of animals and plants is one of the world’s nized from abroad, in particular by invaders from the most ancient landmasses which harbours one of the Indo-Malay Archipelago, once Australia has been in richest biota with a high number of endemisms. Austra- reach for several taxa from the Oriental region. lia’s fauna and flora was only very slowly discovered The fallacy of such a perception of Australia’s “colo- and studied, albeit its many unique elements – from nial” history became obvious only recently when it was kangaroos and cockatoos, lungfishes and lyrebirds to established by use of molecular phylogeny that, for ex- the platypus – have ever since puzzled biogeographers, ample, the most speciose and widely distributed oscine systematists and other naturalists. Next to endemic and passerines (songbirds, comprising more than half of all unique forms evolution has also produced, for example, extant avian species) apparently originated in the Aus- some native marsupials strikingly similar to Old World tralo-Papuan region as part of (eastern) Gondwana and species, such as the bandicoot and the Tasmanian wolf only subsequently colonized the Eurasian continent resembling placental rabbits and carnivores, respec- (Barker et al. 2004). Instead of Australian passerines tively. Even among the fossil fauna a most spectacular being confamilial Northern Hemisphere derivatives and convergence of anatomical specializations of a xylopha- relatively recent invaders, a phylogenetic reconstruction gus (wood-boring) Australian metatherian from the based on two single-copy nuclear gene sequences sug- Oligo-Miocene to an extant marsupial of Australia as gested multiple waves of emigration from Australia well as to the primate Daubentonia of Madagascar has with dispersal into Eurasia, Africa, and the New World, been reported lately (Beck 2009). Australia’s rich native commencing as early as the Eocene. Further evidence avifauna exhibits similar cases of rampant convergent for Australia actually having been the birthplace of evolution; however, being less conspicuous, these were songbirds as part of a large-scale authochthonous radia- not recognized as such until most recently (see below). tion that far exceeded in scope that of the marsupials Australia’s biota was long not only considered peculiar came from passerine fossils in Early Eocene strata (c. but “primitive”, as it soon became evident that this con- 54.6 mya) at Murgon in southeastern Queensland tinent harbours many apparently ancient floral and faunal (Boles 1995), as well as from other molecular studies elements that only survived there, such as e.g. cycads, on birds resulting in a renaissance of higher level sys- lungfishes, monotremes and the many marsupials. In ad- tematics of this vertebrate clade (Edwards & Boles dition to the ancestry of these lineages an exceptionally 2002). Essentially turning the phylogeny of passerine high degree of endemism with many speciose taxa gave birds and significant parts of Australia’s avifauna up- witness to the long isolation of the continent. On the side down, this new viewpoint not only reverses the other hand, from very early on the Australian fauna was classical scenario of oscine biogeography and the struc- considered, albeit erroneously, “impoverished” and “less- ture of their radiation, but also foreshadows similar perfected”, as even Darwin noted (see Ospovat 1981: evolutionary trajectories for other biotic elements in 219). Thus, many naturalists way into the