Ronald Sluys

Global diversity of land planarians (Platyhelminthes, Tricladida, Terricola): a new indicator-taxon in biodiversity and conservation studies

Biodiversity conservation requires prioritization of areas for in situ conservation. In that perspective, the present study documents the global diversity of a component of the soil macrofauna, the land planarians, and concerns an exploratory analysis of their possible role as indicators of biodiversity. Diversity is described by three quantitative methods: (1) hotspots of species richness, selecting areas richest in species, (2) hotspots of range-size rarity, identifying areas richest in narrowly endemic species, and (3) complementarity, prioritizing areas according to their greatest combined species richness. The biodiversity measures of species richness and range-size rarity show a great correspondence in the identification of hotspots of diversity; both measures identify the following seven areas as the most biodiverse for land planarians: Sao Paulo, Florianopolis, western Java, Tasmania, Sri Lanka, North Island/New Zealand, and Sydney. It is discussed to what extent the results for the land planarians correspond with those obtained in other studies that assessed biodiversity hotspots for taxa on a global scale. It is noteworthy that land planarians identify a few global hotspots of diversity that generally do not feature, or only have low rankings, in other studies: New Zealand, southeastern Australia, and Tasmania.

Molecular barcoding and phylogeography of sexual and asexual freshwater planarians of the genus Dugesia in the Western Mediterranean (Platyhelminthes, Tricladida, Dugesiidae)

Planarians of the genus Dugesia have a worldwide distribution with high species diversity in the Mediterranean area. In this area, populations with a triploid karyotype that reproduce by fissiparity are exceptionally frequent, outnumbering the sexual populations. This situation poses interesting questions, such as the age of these asexual lineages, whether they all belong to the same species or whether the triploidization event is recurrent, and what factors (climatic, geographical, historical...) explain the prevalence of these asexual forms. However, asexual populations cannot be assigned to a species due to the lack of copulatory apparatus--the main structure used in species identification. In this study, we have developed a DNA barcoding method, based on COI and ITS-1 sequences, which allows the assignment of the fissiparous forms to sexual species. At the same time, phylogenetic analysis from species of the western Mediterranean have unveiled the presence of species with highly differentiated populations alongside species with a wide distribution and almost no genetic variation. The roles of habitat instability, dispersal capacity and human activities are briefly discussed.

Sperm resorption in triclads (Platyhelminthes, Tricladida)

Summary Triclads use the excess of spermatozoa received from the partner during copulation as an additional source of nutritive material. Digestion of sperm takes place in various sperm resorptive organs, such as the copulatory bursa, lateral bursae, spermiduct, resorptive vesicles, and oviducal tubae. Sperm resorptive organs may concern either newly evolved organs, or result from a change of function in an already existing structure.

A new higher classification of planarian flatworms (Platyhelminthes, Tricladida)

This paper presents a revised classification for the higher taxa within the Tricladida. A historical sketch is provided of the higher classificatory systems of triclad flatworms. As far as possible, the new classification is based on published phylogenetic studies. A phylogenetic tree generalizing currently available hypotheses on the higher-taxon relationships of the Tricladida forms the backbone of the new classification. There is no longer any room in formal classifications for the taxon names Terricola and Paludicola, previously used to indicate the suborders of freshwater and land planarians, respectively. It is a consequence of the new classification that the taxonomic rank of the terrestrial planarians is now at the level of family. A new diagnosis of this family is provided. The taxon name Continenticola denotes a monophyletic group consisting of the freshwater planarians and the terrestrial planarians. At this stage it is difficult to find unequivocal morphological apomorphies enabling a diagnosis for the Continenticola.

Global diversity of free living flatworms (Platyhelminthes, "Turbellaria") in freshwater

This contribution reviews diversity of turbellarian species by biogeographical regions, with comments on species biology. The review draws on the database available at http://www.devbio.umesci.maine.edu/styler/turbellaria. Comparisons between regions suggest that species richness may be at least one order of magnitude higher than the currently reported number of species. In the context of the recent reconstructions of phylogeny of Platyhelminthes based on molecular data, the paper allows inferences as to the history of colonization of freshwaters by turbellarians. Specifically, four, or perhaps six, major invasions of freshwater habitats may have occurred in the Pangean period, each of which gave rise to a monophyletic freshwater taxon. In addition, several occasional invasions by representatives of marine taxa must have taken place.

The genus Dugesia in Australia, with its phylogenetic analysis and historical biogeography (Platyhelminthes, Tricladida, Dugesiidae)

The new species Dugesia notogaea Sluys & Kawakatsu, sp. n. is described from Queensland, Australia, representing the first record of the genus Dugesia for that continent. A phylogenetic analysis of the 68 species of Dugesia resulted in the discovery of a new apomorphy for the genus, and a cladogram showing two major phyletic groups. The distributional range of one group has a western accent, whereas that of the other group has an eastern emphasis; the ranges of these two groups overlap in Africa and the Mediterranean region. We attempt to determine the ancestral area for both the Dugesiidae and Dugesia. A scenario for the historical biogeography of the genus Dugesia is discussed. In this scenario it is presumed that the geological history of the Australasian region enabled Dugesias from southeast Asia to colonize northern Australia.

A monograph of the Dimarcusidae (Platyhelminthes, Seriata, Tricladida)

The triclad family Dimarcusidae contains the species Rhodax evelinae, Opisthobursa mexicana, O. josephinae, Balliania thetisae and Mitchellia sarawakana. A comprehensive description is given of each of these species, covering external features, alimentary system, reproductive system, life cycle, ecology and distribution. Postulated apomorphies of the Dimarcusidae are (1) a penis bulb with gland cells, (2) horizontal orientation of female genital duct or bursal canal, combined with a dorsal opening of the common oviduct or diverticulum and (3) location of the ovaries at some distance posterior to the brain. The genera Rhodax, Opisthobursa and Mitchellia form a monophyletic group, the sistergroup being B. thetisae. The genera Rhodax and Opisthobursa share a sistergroup relationship. The Dimarcusidae should not be classified among the Maricola, Terricola or Paludicola. The family represents a fourth lineage within the Tricladida and is more closely related to the Paludicola and Terricola than to the Maricola.

Ecology and distribution of the freshwater planarian Schmidtea mediterranea in Tunisia

Abstract The ecology of Schmidtea mediterranea, a freshwater planarian, is here described for the first time from Tunisia. The population consists of sexual diploids with a chromosome number of 2n = 8, and reproduces exclusively sexually through the formation of cocoons. Seasonal variation in the number of animals present as well their state of maturity, were correlated with water temperature.

Evidence for the persistence of the land planarian species Microplana terrestris (Müller, 1774) (Platyhelminthes, Tricladida) in microrefugia during the Last Glacial Maximum in the northern section of the Iberian Peninsula

The land planarian species Microplana terrestris (Müller, 1774), shows a wide distribution in the north of the Iberian Peninsula, where mature humid forests can be found. Since most terrestrial planarians require the presence and good condition of wet forests to survive, a parallel evolution of the taxon and its habitat might be expected. Performing molecular analyses (mitochondrial cytochrome oxidase I and nuclear ITS-1 genes) we estimated the demography and biogeographic history of the species in that region. Our results show the species to present levels of genetic diversity likely originating before the Pleistocene. However, it presents a genetic structure that presumably resulted from its survival in various refugees during the Pleistocene glacial cycles. The two main genetic groups, present on the Iberian Peninsula, seem to have different origins: the western one being of Iberian origin, while the eastern group may have been the result of a re-colonization from the north. In both cases, their biogeographical history mirrors their habitat range movements, reinforcing the phylogeographical hypothesis put forward for its preferred habitat, i.e. humid forests.

Morphological stasis in an old and widespread group of species: Contribution to the taxonomy and biogeography of the genus Girardia (Platyhelminthes, Tricladida, Paludicola)

Abstract Material is described that contributes to our understanding of the anatomy of 11 species of the genus Girardia Ball, 1974 and the taxonomy of one species of Romankenkius Ball, 1974. Apart from recently collected specimens, the study for the first time details old syntype material that was recovered for the species G. anceps and G. andina, resulting in the first modern description of the last-mentioned species. Relatively recently collected specimens from new sampling sites are described for G. chilla, G. dorotocephala, G. festae, G. paramensis, and G. tigrina. The new records for G. festae considerably enlarge the known geographic range of this species in South America, particularly east of the Andes. It is shown that contrary to the opinion of earlier workers there is some slight, but invariable, anatomical difference between North and South American specimens of G. tigrina, with the Neotropical animals having a much more muscled bursal canal. This slight anatomical difference suggests that the North and South American forms are actually sibling species. Four new Girardia species are described, three for the South American continent (G. avertiginis, G. capacivasa, G. jugosa) and one from Jamaica (G. bursalacertosa). The study confirms earlier conclusions that generally species of Girardia are anatomically very similar and that therefore species recognition can be difficult. It is striking that taxonomic diversity in the Neotropical Region is low, in that the majority of the freshwater planarians belongs to a single genus, viz. Girardia. It is concluded that Romankenkius michaelseni (Böhmig, 1902) is a junior synonym of R. patagonicus (Borelli, 1901).