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Turbellarian Flatworm Fauna
Diversity of Turbellarian flatworms in the Peruvian Amazon basin
Carolina Noreña Janssen
Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.
List of taxa (23 spp.):
Order CATENULIDA Meixner, 1924
Family Stenostomidae Vejdovsky, 1880
Genus Stenostomum Schmidt, 1848
Stenostomum grande Child, 1902
Stenostomum bicaudatum Kennel, 1889
Stenostomum sp. 1
Stenostomum sp. 2
Order MACROSTOMIDA Karling, 1940
Family Macrostomidae Beneden, 1870
Genus Macrostomum Schmidt, 1848
Macrostomum tenuicauda Luther, 1947
Macrostomum balticum Luther, 1947
Macrostomum sp. 1 (immature)
Family Microstomidae Luther, 1907
Genus Microstomum Schmidt, 1848
Microstomum lineare (Müller, 1773) Örsted 1843
Order LECITHOEPITHELIATA Reisinger, 1924
Family Prorhynchidae Hallez, 1894
Genus Prorhynchus Schultze, 1851
Prorhynchus stagnalis Schultze, 1851
Genus Geocentrophora de Man, 1876
Geocentrophora sp. (cf. applanata (Kennel, 1888) Steinböck 1927)
Order RHABDOCOELA Graff, 1904
Family Dalyelliidae Graff, 1908
Genus Gieysztoria Ruebush & Hayes, 1939
Gieysztoria chiqchi sp. nov.
(Fig. 1-2)
Gieysztoria kasasapa sp. nov.
(Fig.3-4)
Gieysztoria sasa sp. nov.
(Fig. 5-6)
Gieysztoria sp. nov. 4
Genus Sergia Nassonov, 1923
Sergia calae sp. nov.
(Fig. 7-8)
Family Temnocephalidae Monticelli, 1899
Genus Temnocephala Blanchard, 1849
Temnocephala lutzi Monticelli, 1913.
Family Typhl oplanidae Graff, 1909
Genus Mesostoma Örsted, 1844
Mesostoma ehrenbergi (Focke, 1836) Örsted, 1844
(Fig. 9)
Mesotoma ucamara sp . nov.
(Fig. 10-12)
Genus Bothromesostoma Braun, 1885
Bothromesostoma evelinae Marcus, 1946
(Fig. 13)
Genus Olisthanella Voigt, 1892
Olisthanella truncula (Schmidt, 1858) Graff 1913
(Fig. 14)
Family Polycystidae Graff, 1905
Genus Gyratr ix Ehrenberg, 1831
Gyratrix hermaphroditus Ehrenberg, 1831
Order TRICLADIDA Lang, 1884
Family Dugesiidae Ball, 1974
Genus Dugesia Girard, 1850
Dugesia (Girardia) gonocephala ( Duges 1830)
(Fig. 15)
Family Planariidae Stimpson, 1857
Genus Phagocata
Phagocata sp.
(Fig 16)
Photographs:
Fig. 1. Gieysztoria chiqchi : Sagittal section (4µm, Haematoxylin-eosin, 40x).
Fig. 2. Gieysztoria chiqchi : Microphotograph of squashed stylet. Scale bar 50 µm. (Photographed by Cristina Damborenea).
Fig. 3. Gieysztoria kasasapa : Whole mounted specimen in Polyvinyl-lactofenol (length: 750 m m).
Fig. 4. Gieysztoria kasasapa : SEM of extracted stylet. Scale bar 50 µm. (Photographed by Cristina Damborenea).
Fig. 5. Gieysztoria sasa : Sagittal section (4µm, Haematoxylin-eosin, 40x) (Photographed by Cristina Damborenea).
Fig. 6. Gieysztoria sasa : SEM of extracted stylet. Scale bar 50 µm. (Photographed by Cristina Damborenea).
Fig. 7. Sergia calae : Sagittal section (general view). (4µm, Azan, 40x). Scale bar: 50µm.
Fig. 8. Sergia calae : Habitus (length: 1mm).
Fig. 9. Mesostoma ehrenbergi . Sagittal section ( 4µm, Azan, 40x).
Fig. 10. Mesostoma ucamara : Habitus (length: 1mm).
Fig. 11. Mesostoma ucamara : Sagittal section (oral pore). (4µm, Azan, 40x). Scale bar: 25 µm.
Fig. 12. Mesostoma ucamara : Sagittal section (general view). (4µm, Azan, 40x). Scale bar: 25 µm.
Fig. 13. Bothromesostoma evelinae. Sagittal section (4µm, Azan, 40x).
Fig. 14. Olisthanella truncula . Sagittal section (4µm, Azan, 40x).
Fig. 15. Dugesia gonocephala (tentative determination) (Photographed by Daniel H. Shain).
Fig. 16. Phagocata sp. (Photographed by Daniel H. Shain).
Methodology:
All samples were processed alive in the field in order to obtain information about natural coloration, size and type of locomotion. Specimens were then fixed for subsequent processing in the laboratory (i.e., photography, histology, drawings, and sagittal reconstructions). It is necessary to emphasize the relationship between numbers of individuals and species. Whereas the number of individuals was always very scarce, the number of species is high. In addition, many congeneric species exhibit very similar external and histological phenotypes (e.g., Stenostomum ), which hinders species identifications and accurate estimates of species diversity.
Some species (listed as sp. in the table) were not found in sufficient numbers to permit correct identification or - if necessary - a reliable new description. Of course this study gives an deficient image of the Amazonian turbellarian fauna, more sampling and more investigation are needed, but the discovery of these species allows us to infer that this area have a high specific diversity.
Abstract of research findings:
The Western Amazon is a hotspot of biodiversity for many aquatic taxa and yet is one of the most poorly known regions on Earth for knowledge of turbellarian flatworms.
Most of the well-known Platyhelminthes for the Amazon basin belongs to the parasitic classes (Neodermata): Cestoda, Trematoda and Monogenea (Thatcher 1993, Carvalho et al. 2001, Marques et al. 2003, Rego 2004, Belmont-Jegu et al 2004) whereas the free living Platyhelminthes are almost unknown. Nowadays only two species have been cited for the whole Amazon River (floodplain and tributaries): Xenostenostomum microstomoides Reisinger, 1976 (Reisinger 1976), Dugesia fissipara (Kennel 1888 (1889)) captured near the Amazon's estuary. Therefore, data or information of more than 350.000 km 2 (during the wet season) of Amazonian flooded area ( Amazon River and tributaries) is lacking.
On the other hand, regarding Peru itself the information about the turbellarians is restricted to the arid Pacific coast near Lima ( Du Bois-Reymond Marcus 1958) and the high altitude Lake Titicaca (4200 m) ( Beauchamp 1939) .
Here we report results of the first ever survey of turbellarian flatworms collected in the Peruvian Amazon based in the proyect UCAMARA.
During the dry season was carried out the expedition to the national park Pacaya-samiria, and was focused mainly in the macrophytes communities know as "floating meadows" and macrophytes of the lakes-shores.
Aquatic macrophytes are important components of habitat complexity and heterogeneity because the dominated inshore zones of lakes where species packing and niche segregation apparently occurs. Such habitats may be spatially complex and support diverse communities. Macrophytes may influence habitat selection and ecological relationships different kind of species of vertebrates (Petry et al, 2003) and invertebrates.
23 species (see List of Taxa. ) were registered, of which at least five are new to science, including one species of the genus Sergia (F. Dalyellidae, O. Rhabdocoela): Sergia calae , one pertain to the genus Mesostoma (F. Typhloplanidae, O. Rhabdocoela): Mesostoma ucamara and three new species of the genus Gieysztoria (F. Dalyellidae, O. Rhabdocoela): Gieysztoria chiqchi, G. kasasapa , and G. sasa.
Phylogenetic and biogeographic considerations.
The biodiversity of free-living Platyhelminthes (Turbellaria) in the Southern zoogeographical regions originating from Gondwana, like the Neotropical region, remain relatively unknown. The most exhaustive studies of "Turbellaria" in this region were conducted in Brazil (Marcus 1943-70, du Bois-Reymond Marcus 1951-58).
Within the Orders described for the Pacaya-Samiria National Park . The genus Stenostomum (F. Stenostomidae Order Catenulida ) is the most broadly distributed and best represented genus of freshwater microturbellarians. It appears worldwide, at times widely distributed over a region and at other times limited to small areas. However, this genus is known for its ambiguous morphological and anatomical diagnostic characters; therefore, it is possible that many species within this genus have been misidentified.
Within the order Macrostomida , the Macrostomidae is the most abundant family. Seventy-five percent of the Macrostomida species belong to this family. Members of the family Macrostomidae are found in a variety of habitats. Representatives of the genus Macrostomum are particularly ubiquitous and can be found in limnic, marine, and brackish environments. The species belonging to this order found in Pacaya Samiria National Reserve are the following: Macrostomum balticum Luther, 1947, known for the north of Europe (sandy sediments) and Jamaica (rook-pools). Whereas for Macrostomum tenuicauda Luther, 1947 ( well-known in north of Europe ) this is the first record for South America .
The distribution of Microstomum lineare (Müller, 1773) Örsted 1843 is cosmopolitan within the northern hemisphere, but this is the first record for the Amazon River and the second one for South America (first record: Santa Fé , Argentina , Noreña Janssen 1995)
The order Lecithoepitheliata includes two families. The family Gnosonesimidae, from marine environments, and the family Prorhynchidae, from freshwater. Both families are poorly represented in the Gondwanian areas, only 6 species of 27 are actually known for this region. The species belonging to this Order found in Pacaya Samiria are: Prorhynchus stagnalis Schultze, 1851 (F. Prorhynchidae) and Geocentrophora sp. (cf. applanata (Kennel, 1888) Steinböck 1927 (F. Prorhynchidae). They are not new species, sure, but they are new records for the whole Amazon basin (they were mentioned for the first time by Marcus (1946) for the south of Brazil ). These records increase the area of distribution of these species and open new possibilities for distribution studies and zoogeographical models inside the order Lecitoepitheliata.
Among members of the suborder Dalyellioda (Order Rhabdocoela) , the genus Gieysztoria (F. Dalyelliidae) is the most prominently represented in the Gondwanian regions, and therefore in the studied region. Of the 40 species of dalyellids known to occur in this region, 40 are species of Gieysztoria (3 of them, new species described during the project). The genus Gieysztoria Ruebush & Hayes, 1939 includes approximately 74 species, but only Gieysztoria ornata and Gieyzstoria rubra can be considered cosmopolitan.
The cuticular stylet of the Gieysztoria is a structure of special interest from comparative anatomical as well as taxonomical viewpoints. The anatomical construction of this structure is the same within the genus: girdle and spines, but shows a great inter-specific variability in the shape, number, and disposition of the spines and the consistency of the girdle (Brusa et al, 2003).
We can found this variety extended a long the genus Gieysztoria, but it is extreme manifested in the species of the southern hemisphere. Concretely in the species described by Marcus (Marcus 1946) for Brazil, Therriault for Central America (Therriault & Kolasa, 1999), by Hartenstein (Hartenstein & Dwine 2000) and Hochberg (Hochberg & Cannon 2001) for Australia, by Brusa for Argentina (Brusa et al, 2003) and more recently by Artois for Botswana (Artois et al, 2004).
In general, and with regard to the genus Gieysztoria we can distinguish between two big groups based on the stylet. A group formed by the species with symmetrical stylet (aequales) and another group with asymmetric or very irregular stylet (inaequales). The first group is broadly represented in the northern hemisphere, while the second group is distributed preferably in the southern hemisphere (Noreña et al 2003).
The second genus described for Pacaya Samiria is: Sergia Nassonov, 1923. This genus is characterized mainly by the lack of cuticle structures in the male copulatory organ (Nassonov 1923; Luther 1955), and is therefore clearly distinguishable from other genera of the Family Dalyelliidae. Only two species comprise the genus Sergia , i.e., S. sergia (Beklemischev, 1918) Nassonov 1923 and S. mancala Marcus & Marcus, 1957. Sergia sergia is restricted to the northern Hemisphere, while S. mancala has only been found in Zaire (Africa ).
In contrast, well represented and distributed genera Dalyellia (7 species) and Microdalyellia (45 species) in Eurasia are poorly represented in the Neotropical regions, with one and four species respectively.
Based on the obtained data, we can suppose that the evolutionary steps of the Dalyellioida followed different path in Gondwana and in Laurasia. The members of genus Gieysztoria could has diverged in the group's Dalyellia and Microdalyellia in Laurasia, and in more complex forms of Gieysztoria (mainly in the male copulatory stylets) in Gondwana. It is possible that the representatives of Dalyellia and Microdalyellia found in Gondwanian regions are introduced species.
It should be noted that in general, the origin of members of suborder Typhloplanoida ( Order Rhabdocoela) , but not the origin of the species of different genera is pre-Gondwanian. For example, the genus Castrada , while amply represented in the Nearctic and Palearctic regions (47 species), has never been reported for the Gondwanian regions. For this reason, we can suppose that the evolution and divergence of the species of Castrada occurred after the separation of Gondwana.
On the other hand, Mesostoma Örsted, 1844, is a broadly distributed genus, with more than 44 well-known species (Tyler & Bush 2003; Noreña Janssen & Faubel 1992). It is important to note that while some species are highly cosmopolitan [e.g. M. ehrenbergi (Focke, 1836), M. lingua (Abildgaard, 1789)] , other species have been captured only in restricted areas (e.g., M . africanum Kolasa, 1976, M. extremeniensis Noreña et al., 1999, M. tubiseminalis Smith, 1998). Regarding to Mesostoma ucamara n. sp . , the species described during this study, we can deduce that M. ucamara is closely related to M. productum , and similar to M. ewerum, M. magnum and M. georgianum. Whereas M. productum is a species with wide distribution in Europe (also been mentioned for Argentina and United States ), M. ewerum , and M. magnum belongs to Africa and Australia respectively. Fact that seems to indicate a certain grouping or relationship among the different species found in continents originated from Gondwana. Probably the genus Mesostoma has their origin prior to the splitting of Gondwana, but most speciation events appear to have occurred after the split.
Publications:
Two new rhabdocoels (Platyhelminthes) from the Peruvian Amazon Floodplain. Noreña, C.; Damborenea, C. & Escobedo Torres, M. - Biodiversity & Conservation - , 2005 (in press).
New species of Gieysztoria (Platyhelminthes, Rhabdocoela) from Peruvian Amazon floodplain with description of their stylet ultrastructure. Damborenea, C., Brusa, F. & Noreña, C. - Journal of Natural history (submitted)
Aquatic faunal survey of Peruvian Amazon floodplain - Biology, distribution and taxonomy of the free-living Platyhelminthes- Noreña, C.; Brusa, F ., Escobedo Torres, M . & Damborenea, C. Zootaxa (in prep)
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