| 1. |
- Guidetti, Roberto, et al.
(författare)
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Morphological and molecular analyses on Richtersius (Eutardigrada) diversity reveal its new systematic position and lead to the establishment of a new genus and a new family within Macrobiotoidea
- 2016
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Ingår i: Zoological Journal of the Linnean Society. - 0024-4082 .- 1096-3642. ; 178:4, s. 834-845
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Tidskriftsartikel (refereegranskat)abstract
- Important contributions have been made to the systematics of Eutardigrada in recent years, but these have also revealed that several taxa are polyphyletic and that cryptic species are present. To shed light on the taxonomy and systematic position of the genus Richtersius (Eutardigrada, Macrobiotoidea), six populations attributed to Richtersius coronifer were collected and analysed from morphological (light and scanning electron microscopy) and molecular (mitochondrial cytochrome oxidase subunit 1, 18S, 28S) points of view. In particular, a new morphometric index (claw common tract: length of the common tract of the claw/total claw length × 100) and a new morphological character (stalk system) were introduced. Our integrative study was able to unveil the ‘cryptic’ species diversity within Richtersius, showing that the genus contains more than one evolutionary lineage. A morphological peculiarity in the animals of all lineages is the dimorphism in the morphology of the cuticle. Cuticular pores are present in the newborns and are lost with the first moult; this morphological change represents a novelty in the life cycle of eutardigrades. The phylogenetic analyses carried out on Richtersius populations and other Macrobiotoidea show that Richtersius is closely related to Macrobiotus islandicus, whereas Adorybiotus granulatus is more related to Richtersius and M. islandicus than to other members of the genus Macrobiotus (type genus of Macrobiotidae); therefore, the genus Macrobiotus and the family Macrobiotidae are not monophyletic. Based on these results, the new genus Diaforobiotus (for M. islandicus) and the new family Richtersiidae (composed of Richtersius, Diaforobiotus gen. nov., and Adorybiotus) are established.
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| 2. |
- Guidetti, Roberto, et al.
(författare)
-
Morphological and molecular analyses on Richtersius (Eutardigrada) diversity reveal its new systematic position and lead to the establishment of a new genus and a new family within Macrobiotoidea
- 2016
-
Ingår i: Zoological Journal of the Linnean Society. - : Oxford University Press. - 0024-4082 .- 1096-3642. ; 178:4, s. 834-845
-
Tidskriftsartikel (refereegranskat)abstract
- Important contributions have been made to the systematics of Eutardigrada in recent years, but these have also revealed that several taxa are polyphyletic and that cryptic species are present. To shed light on the taxonomy and systematic position of the genus Richtersius (Eutardigrada, Macrobiotoidea), six populations attributed to Richtersius coronifer were collected and analysed from morphological (light and scanning electron microscopy) and molecular (mitochondrial cytochrome oxidase subunit 1, 18S, 28S) points of view. In particular, a new morphometric index (claw common tract: length of the common tract of the claw/total claw length × 100) and a new morphological character (stalk system) were introduced. Our integrative study was able to unveil the ‘cryptic’ species diversity within Richtersius, showing that the genus contains more than one evolutionary lineage. A morphological peculiarity in the animals of all lineages is the dimorphism in the morphology of the cuticle. Cuticular pores are present in the newborns and are lost with the first moult; this morphological change represents a novelty in the life cycle of eutardigrades. The phylogenetic analyses carried out on Richtersius populations and other Macrobiotoidea show that Richtersius is closely related to Macrobiotus islandicus, whereas Adorybiotus granulatus is more related to Richtersius and M. islandicus than to other members of the genus Macrobiotus (type genus of Macrobiotidae); therefore, the genus Macrobiotus and the family Macrobiotidae are not monophyletic. Based on these results, the new genus Diaforobiotus (for M. islandicus) and the new family Richtersiidae (composed of Richtersius, Diaforobiotus gen. nov., and Adorybiotus) are established.
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| 3. |
- Stein, Martin, 1976-
(författare)
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Evolution and taxonomy of Cambrian arthropods from Greenland and Sweden
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Arthropods have a rich fossil record spanning the Phanerozoic. Biomineralized forms such as the extinct trilobites are particularly common and are proven index fossils for biostratigraphy. Forms with an unmineralized cuticle are more rare, preserved only in so called konservat lagerstätten. Cambrian strata of Greenland have yielded rich trilobite faunas with potential for intercontinental correlation of Cambrian strata, but also an exceptionally preserved fauna, the Sirius Passet Lagerstätte. The first part of this thesis is concerned with trilobite biotratigraphy of the provisional Cambrian Series 2 in Greenland. The second part is concerned with exceptionally preserved arthropods from the Sirius Passet Lagerstätte, but also from 'Orsten' deposits from the Cambrian of Sweden. Perissopyge phenax occurs in the Henson Gletscher and Paralleldal formations spanning the Series 2 and 3 boundary interval in North Greenland. It also occurs in the Sekwi Formation of Yukon Territory, demonstrating that the species may hold potential for correlation within Laurentia. An indeterminate species of Perissopyge is shown to occur in the Ella Island Formation of North-East Greenland together with Olenellus cf. hanseni, which is similar to Olenellus cf. truemani described from the Henson Gletscher Formation. If this correlation is further corroborated it would offer a first tie-point for the An t'Sron Formation of North-West Scotland which yields Fritzolenellus lapworthi, herein reported for the first time from the Bastion Formation which underlies the Ella Island Formation. Oelandocaris oelandica from ‘Orsten’ deposits in the Cambrian series 3 and 4 boundary interval in Sweden is an early representative of the Crustacean stem lineage. Kiisortoqia avannaarsuensis is a new arthropod from the Sirius Passet Lagerstätte with robust antennulae strikingly similar to the 'raptorial' limb of the problematic anomalocaridids. The ventral morphology of the 'bivalved' Isoxys volucris is described for the first time and compared with other species assigned to Isoxys from Cambrian lagerstätten around the world. Finally, Siriocaris trolla, is a new arthropod that similarities with trilobites and certain ‘trilobitomorphs’ but seems to lack important synapomorphies of these taxa, though this may be due to preservational limitations in the material at hand.
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| 4. |
- Willems, Wim, et al.
(författare)
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Meiofauna of the Koster-area, results from a workshop at the Sven Lovén Centre for Marine Sciences (Tjärnö, Sweden)
- 2009
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Ingår i: Meiofauna Marina. - : Pfeil. - 1611-7557. ; 17, s. 1-34
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Tidskriftsartikel (refereegranskat)abstract
- During a two-week workshop held at the Sven Lovén Centre for Marine Sciences on Tjärnö, an island on the Swedish west-coast, meiofauna was studied in a large variety of habitats using a wide range of sampling tech- niques. Almost 100 samples coming from littoral beaches, rock pools and different types of sublittoral sand- and mudflats yielded a total of 430 species, a conservative estimate. The main focus was on acoels, proseriate and rhabdocoel flatworms, rotifers, nematodes, gastrotrichs, copepods and some smaller taxa, like nemertodermatids, gnathostomulids, cycliophorans, dorvilleid polychaetes, priapulids, kinorhynchs, tardigrades and some other flatworms. As this is a preliminary report, some species still have to be positively identified and/or described, as 157 species were new for the Swedish fauna and 27 are possibly new to science. Each taxon is discussed separately and accompanied by a detailed species list.
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