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Specimens of Ligidium sp. (Crustacea, Isopoda, Oniscidea) collected from Kanagawa Prefecture in Japan were found to be infected with parasitic nematodes. We have obtained two Mermithidae (Nematoda) by dissecting the fresh specimen and from the dead specimen of Ligidium, which marks the second known discovery of a mermithid infection in the order Isopoda. Herein, a report on the nuclear 28S rDNA and 18S rDNA sequence of the isolated Mermithidae nematodes and on the morphology of the juveniles is provided.

The genetic diversity of the genus Ligidium in Hokkaido and Niigata, northern Japan, was investigated by analyzing the cytochrome c oxidase subunit 1 (CO1) region in the mitochondrial DNA (mtDNA). The genetic diversity in Hokkaido was much lower than that in Niigata. Nine different operational taxonomic units (OTUs) were identified. Only a single OTU, most likely Ligidium japonicum, was found in Hokkaido, whereas all nine OTUs were found in Niigata. Using the mtDNA evolutionary rate determined for the marine invertebrate Haptosquilla pulchella (Miers, 1880), population expansion for OTU1 in Hokkaido was estimated to have occurred at 12,600 years BP, suggesting that Ligidium underwent a bottleneck due to glacial cooling, and the population then expanded after postglacial warming. Assuming that the expansion of the OTU1 population occurred at 9600 years BP, when the sea surface temperature rose offshore of Tokachi in the Northwestern Pacific, the evolutionary rate (µ) of the mtDNA CO1 region in Ligidium is calculated as: 0.087 (95% confidence intervals: min: 0.042–max: 0.12) (substitutions/site/million years). The presence of a haplotype common to Hokkaido and Niigata implies that the haplotype migrated across the Tsugaru Strait. Considering that geological evidence indicates that the Tsugaru Strait was continuously present even during the last glacial maximum when the sea level was at its lowest, accidental transport by human beings or animals might have been critical to the migration of Ligidium.

A new species of terrestrial Isopoda, Ligidium acutangulum sp. nov., is described and illustrated based on material from China. The new species can be diagnosed by the apical part of the pleopod 2 endopod being acutely triangular, the inner margin straight, and the outer margin concave near a well-developed process. Type specimens are deposited in the Insect Museum, Jiangxi Agricultural University, Nanchang, P. R. China.

We conducted a comprehensive review of blue isopods in Japan by collecting isopod species from eight sites located on three Japanese islands (Honshu, Kyushu and Okinawajima). We also interviewed Japanese soil-fauna researchers and retrieved data from the Internet detailing isopod collections in Japan. From analysis of the complete data set, we conclude that a total of eight species from six families (i.e., Ligiidae, Alloniscidae, Philosciidae, Armadillidae, Porcellionidae and Armadillidiidae), excluding two unidentified species, have been observed at 18 Japanese sites. The distributional range of the blue isopods covered the whole of Japan (from Okinawajima Island to Hokkaido). Examination of transmission electron microscope (TEM) images revealed non-enveloped virions in the epithelial cell cytoplasm of the blue coloured Armadillidium vulgare (Latreille, 1804) from Japan. We designed primers for amplifying partial sequences from the major capsid protein (MCP) gene from invertebrate iridescent viruses (IIVs). The predicted amino acid sequences of the MCP gene from IIV isolated from the blue coloured isopods, A. vulgare, Porcellio scaber Latreille, 1804, Burmoniscus kathmandia (Schmalfuss, 1983), and Ligidium koreanum Flasarova, 1972, collected from Japan, were completely congruent with IIV-31 from the U.S.A. However, nucleotide sequence analysis showed that genetic variation exists among the IIV-31 species collected from the four collection sites in Japan and the North American IIV-31 species.

[The marsupium of the primarily terrestrial isopod sub-order Oniscidea is modified from the basal marine design and represents one of the key evolutionary innovations enabling the invasion of land habitats. In the Ligiidae, the marsupial chamber is provisioned with water from the external environment via a capillary channel formed from the apposed 6th and 7th pereiopods. The other oniscidean families possess a 'closed' marsupium, isolated from the pleural water-conducting system and provisioned with water and ions by sternal cotyledons. How these different modes of fluid provisioning influence the ionic composition of marsupial fluid and its osmotic and ionic relationship to the haemolymph remains essentially unstudied. We analysed the ionic composition (Na+, K+, Ca2+, Cl–, pH) of marsupial fluid and haemolymph in 4 species of Oniscidea: Ligia occidentalis (Ligiidae), Ligidium lapetum (Ligiidae), Alloniscus perconvexus (Alloniscidae), and Armadillidium vulgare (Armadillidiidae). In all four species, ion concentrations show a broad similarity between marsupial fluid and haemolymph, but with elevated potassium concentrations in the 'closed'-marsupium species. The sternal integument of Armadillidium vulgare is permeable to inulin and the volume of the combined marsupial fluid and haemolymph is not significantly enlarged compared to the haemolymph of non-gravid females. Accordingly, the 'closed' marsupium of A. vulgare can be viewed as a functional subdivision of the haemolymph space. In Ligidium lapetum, marsupial water is derived from external freshwater sources, but marsupial fluid [Na+] and [Cl–]are actually significantly higher than haemolymph values. This species thus possesses an effective means of ion provisioning, paralleling that seen in the 'closed' marsupial species., The marsupium of the primarily terrestrial isopod sub-order Oniscidea is modified from the basal marine design and represents one of the key evolutionary innovations enabling the invasion of land habitats. In the Ligiidae, the marsupial chamber is provisioned with water from the external environment via a capillary channel formed from the apposed 6th and 7th pereiopods. The other oniscidean families possess a 'closed' marsupium, isolated from the pleural water-conducting system and provisioned with water and ions by sternal cotyledons. How these different modes of fluid provisioning influence the ionic composition of marsupial fluid and its osmotic and ionic relationship to the haemolymph remains essentially unstudied. We analysed the ionic composition (Na+, K+, Ca2+, Cl–, pH) of marsupial fluid and haemolymph in 4 species of Oniscidea: Ligia occidentalis (Ligiidae), Ligidium lapetum (Ligiidae), Alloniscus perconvexus (Alloniscidae), and Armadillidium vulgare (Armadillidiidae). In all four species, ion concentrations show a broad similarity between marsupial fluid and haemolymph, but with elevated potassium concentrations in the 'closed'-marsupium species. The sternal integument of Armadillidium vulgare is permeable to inulin and the volume of the combined marsupial fluid and haemolymph is not significantly enlarged compared to the haemolymph of non-gravid females. Accordingly, the 'closed' marsupium of A. vulgare can be viewed as a functional subdivision of the haemolymph space. In Ligidium lapetum, marsupial water is derived from external freshwater sources, but marsupial fluid [Na+] and [Cl–]are actually significantly higher than haemolymph values. This species thus possesses an effective means of ion provisioning, paralleling that seen in the 'closed' marsupial species.]

The phylogeny of Greek populations of the terrestrial isopod genus Ligidium is reconstructed based on three mtDNA gene segments: 12S rRNA, 16S rRNA and COI. Two widely distributed European species, as well as three outgroups belonging to different isopod genera, were also included in the analyses. The samples used represent almost all Ligidium species known to occur in Greece, as well as several populations of unknown specific status plus some new records. Phylogenetic analyses of the combined data set were performed using Bayesian inference and maximum parsimony. The two main sister clades with good support indicate the sympatric differentiation of two lineages in southern continental Greece (Peloponnisos), where Ligidium populations exhibit a mosaic distribution of sibling species. The insular populations of the Aegean Islands show increased genetic divergence and form separate clades. The presence of a third lineage of Asiatic origin is strongly suggested by both the molecular phylogeny and morphology. The only presumably valid diagnostic morphological character exhibits only partial correspondence to well supported clades of the molecular phylogeny. Genetic differentiation between populations is very high, a fact that can be attributed to the strict ecological specialization of these animals that leads to increased levels of isolation even between populations that are in close proximity. As a consequence, Greek Ligidium populations, especially those present on islands, are unique genetic pools and extremely vulnerable to extinction. © 2006 The Authors. 35 459 472 Cited By :22

We investigated mtDNA genetic differentiation and the phylogenetic relationships of 11 populations of the oniscidean genus Ligidium. We studied nine populations from Greece, assigned to three nominal species (L. euboicum, L. germanicum and L. beieri), and two from central Europe (L. germanicum and L. hypnorum), applying RFLP analysis of two mtDNA segments (12S rDNA and 16S rDNA) amplified by PCR. The analysis revealed seven monomorphic and four polymorphic populations, and 17 different haplotypes, each one present in one population only. Several restriction enzymes produced population specific patterns, enabling discrimination among the different populations. The estimated net nucleotide divergence between populations ranges from 1.06 to 16.52%, while the high NST value (0.96) indicates the existence of increased interpopulation genetic differentiation that can be attributed to the extreme isolation among Ligidium populations. The relationships between haplotypes and populations are not congruent with their geographical distribution and the established taxonomy within the genus.

[A new species of the genus Ligidium, L. jiuzhai, is described. The specimens were collected in Jiuzhai Gully (32.9° N 103.8° E), Sichuan Province, China. The diagnostic characters of the new species are: margin of rounded apex of telson with setules; dactylus of pereopod 7 with 3 long setules and 3 setae; rounded apex of endopod of pleopod 2 with 6 denticles and 1 seta; maxillipedal palp not folded; inner lobe of maxillule with 3 subapical setae.Une nouvelle espece du genre Ligidium, L. jiuzhai, est decrite. Les specimens ont ete collectes a Jiuzhai Gully (32.9° N 103.8° E), province de Sichuan, Chine. Les caracteres diagnostiques de la nouvelle espece sont: bord de l'apex arrondi du telson avec setules; dactyle du pereiopode 7 avec 3 longues setules et 3 soies; apex arrondi de l'endopodite du pleopode 2 avec 6 denticules et une soie; palpe du maxillipede non replie; lobe interne de la maxillule avec 3 soies subapicales., A new species of the genus Ligidium, L. jiuzhai, is described. The specimens were collected in Jiuzhai Gully (32.9° N 103.8° E), Sichuan Province, China. The diagnostic characters of the new species are: margin of rounded apex of telson with setules; dactylus of pereopod 7 with 3 long setules and 3 setae; rounded apex of endopod of pleopod 2 with 6 denticles and 1 seta; maxillipedal palp not folded; inner lobe of maxillule with 3 subapical setae.Une nouvelle espece du genre Ligidium, L. jiuzhai, est decrite. Les specimens ont ete collectes a Jiuzhai Gully (32.9° N 103.8° E), province de Sichuan, Chine. Les caracteres diagnostiques de la nouvelle espece sont: bord de l'apex arrondi du telson avec setules; dactyle du pereiopode 7 avec 3 longues setules et 3 soies; apex arrondi de l'endopodite du pleopode 2 avec 6 denticules et une soie; palpe du maxillipede non replie; lobe interne de la maxillule avec 3 soies subapicales.]

Η πραγματική ταξινομική κατάσταση των πληθυσμών του γένους Ligidium, κυρίως αυτών που κατανέμονται στη νότια Ελλάδα, δεν είναι ξεκάθαρη. Αυτό συμβαίνει γιατί η απόληξη του δεύτερου ενδοποδίτη του πλεοποδίου των αρσενικών, που αποτελεί σημαντικό διαγνωστικό χαρακτήρα, ποικίλλει και η εύθραυστη δομή της μπορεί εύκολα να καταστραφεί και κατ’ επέκταση να οδηγήσει σε μια μη ακριβή περιγραφή της κατάστασης αυτού του χαρακτήρα. Οι παλαιότερες μελέτες των φυλογενετικών σχέσεων των ισοπόδων του γένους Ligidium, με χρήση μοριακών δεικτών είναι ολιγάριθμες. Πιο συγκεκριμένα, για τη μελέτη πληθυσμών του γένους Ligidium από τον ελλαδικό χώρο έχει γίνει μόνο μια μελέτη στην οποία χρησιμοποιήθηκε η τεχνική της αλληλούχισης του DNA. Η παρούσα μεταπτυχιακή εργασία αποτελεί την πιο εκτεταμένη φυλογενετική ανάλυση μέσα στο γένος Ligidium. H έρευνα επιλέχθηκε να γίνει σε επίπεδο ατόμων συλλέγοντας πολλούς πληθυσμούς από διαφορετικές περιοχές, οι οποίοι ανήκουν είτε στο ίδιο είτε σε διαφορετικά ποτάμια συστήματα. Συγκεκριμένα χρησιμοποιήθηκαν μοριακοί δείκτες από 26 πληθυσμούς ισοπόδων, οι οποίοι καλύπτουν σχεδόν όλο το φάσμα των ειδών, που ανήκουν στo γένος Ligidium και διαβιούν στον ελλαδικό χώρο. Η πειραματική προσέγγιση περιελάμβανε τον πολλαπλασιασμό αλληλουχιών με τη μέθοδο της αλυσιδωτής αντίδρασης πολυμεράσης (PCR), τον προσδιορισμό της αλληλουχίας τους, και τη στατιστική και φυλογενετική ανάλυσή τους. Οι αλληλουχίες που χρησιμοποιήθηκαν προέρχονται από τους πυρηνικούς γονιδιακούς τόπους ITS1, 5.8s, ITS2 οι οποίοι είναι από τους πιο ευρέως διαδεδομένους μοριακούς δείκτες για μελέτες σε επίπεδο πληθυσμών και ειδών και δεν έχουν προηγουμένως μελετηθεί για άλλα χερσαία ισόποδα. Οι αλληλουχίες επεξεργάστηκαν με τρεις μεθόδους φυλογενετικής ανάλυσης οι οποίες είναι η μέθοδος σύνδεσης γειτόνων (Neighbor-Joining), η Μέθοδος Μέγιστης Φειδωλότητας (Maximum Parsimony) και η Μπεϊεσιανή Συμπερασματολογία (Bayesian Inference). To τελικό σύνολο των στοιχισμένων αλληλουχιών, μετά την αφαίρεση τμημάτων από την αρχή και το τέλος τους, είχε μήκος 614 βάσεων. Σε γενικές γραμμές τα αποτελέσματα που προέκυψαν από τη χρήση των εν λόγω πυρηνικών δεικτών και των τριών φυλογενετικών μεθόδων (BI, MP, NJ), τόσο ως προς τα δέντρα όσο και ως προς τις γενετικές αποστάσεις, δεν θεωρούνται ασφαλή για την εξαγωγή ικανοποιητικών συμπερασμάτων. Επίσης πραγματοποιήθηκε σύγκριση αποτελεσμάτων προηγούμενων μελετών με αυτά που προκύπτουν από τη δική μας έρευνα, καθώς και αξιολόγηση της αξιοπιστίας των μοριακών δεικτών που χρησιμοποιήθηκαν. Terrestrial isopods (suborder Oniscidea) form a monophyletic group within the crustacean order Isopoda that has conquered almost all terrestrial environments. The family Ligiidae, forming the sister group to all the other Oniscidea (with the possible exception of Tylidae) consists of five genera. The genus Ligidium is the most species-rich genus within Ligiidae and consists of 47 species distributed throughout the northern hemisphere, from western Europe to Japan and North America. The taxonomy of the genus has hitherto been based on a few morphological characters most of which exhibit high intrapopulation variation. As a consequence, the current taxonomy of Ligidium is problematic and the validity of described species cannot be taken for granted. Molecular data for only a few species have been used in broader phylogenetic analyses within terrestrial isopods In the present study we perform the most extensive phylogenetic analysis within the genus Ligidium. We attempt to clarify the taxonomic status of the various populations and try to identify geographical patterns in genealogical affinities that might help us reconstruct the evolutionary history of the respective species. We used three nuclear ribosomal gene segments (ITS1, 5.8s, ITS2) for the phylogenetic analysis of Ligidium populations, which were collected from several locations in Greece, representing almost all species reported from this region. For comparative reasons, we have also included one population from each of the two widespread European species, L. hypnorum, Cuvier, 1792 and L. germanicum, Verhoeff, 1901. Since the taxonomy within the genus is still ambiguous, and because most morphological characters are not dependable for species identification, we chose to perform the analysis at the individual level, sampling several populations from different locations that belong either to the same or to different river systems. Fragments of the three rDNA genes (ITS1, 5.8s, ITS2) were amplified using the polymerase chain reaction (PCR) technique and then individual sequences were determined via automated sequencing. We compare the results which occurred from our study with those of previous ones and we evaluate the plylogenetic utility of the molecular markers that we used. In general the results that came out by the analyses of three following phylogenetic methods Neighbor joining (NJ), Maximum parsimony (MP) and Bayesian Inference (BI), are not considered to be safe for making generalized conclusions.

We investigated mtDNA genetic differentiation and the phylogenetic relationships of 11 populations of the oniscidean genus Ligidium. We studied nine populations from Greece, assigned to three nominal species (L. euboicum, L. germanicum and L. beieri), and two from central Europe (L. germanicum and L. hypnorum), applying RFLP analysis of two mtDNA segments (12S rDNA and 16S rDNA) amplified by PCR. The analysis revealed seven monomorphic and four polymorphic populations, and 17 different haplotypes, each one present in one population only. Several restriction enzymes produced population specific patterns, enabling discrimination among the different populations. The estimated net nucleotide divergence between populations ranges from 1.06 to 16.52%, while the high NST value (0.96) indicates the existence of increased interpopulation genetic differentiation that can be attributed to the extreme isolation among Ligidium populations. The relationships between haplotypes and populations are not congruent with their geographical distribution and the established taxonomy within the genus. 74 255 264 Cited By :6

This study reports the species of five families of terrestrial isopod crustaceans (oniscoids) from Florida. Twelve species including three each of Tylos and Ligia and one each of Ligidium, Vandeloscia, Sayoscia, Rhyscotus, and a new genus, Floridoscia (with a new species), are included. Another common species from Florida. Philoscia floridana Van Name. is placed in a new genus, Ocelloscia. Illustrations, notes on habitat, and distribution maps are included for all 12 species.

11. Ligidium germanicum Verh. 3 junge Tiere am 28. X. in der Smoganica bei St. Lucia gefunden. Sie d��rften durch Regeng��sse hinabgetrieben worden sein., Published as part of K. W. Verhoeff, 1929, Arthropoden aus s��dostalpinen H��hlen., pp. 41-55 in Mitteilungen ��ber H��hlen- und Karstforschung 1929 on page 53

We investigated mtDNA genetic differentiation and the phylogenetic relationships of 11 populations of the oniscidean genus Ligidium. We studied nine populations from Greece, assigned to three nominal species (L. euboicum, L. germanicum and L. beieri), and two from central Europe (L. germanicum and L. hypnorum), applying RFLP analysis of two mtDNA segments (12S rDNA and 16S rDNA) amplified by PCR. The analysis revealed seven monomorphic and four polymorphic populations, and 17 different haplotypes, each one present in one population only. Several restriction enzymes produced population specific patterns, enabling discrimination among the different populations. The estimated net nucleotide divergence between populations ranges from 1.06 to 16.52%, while the high NST value (0.96) indicates the existence of increased interpopulation genetic differentiation that can be attributed to the extreme isolation among Ligidium populations. The relationships between haplotypes and populations are not congruent with their geographical distribution and the established taxonomy within the genus.

The species Ligidium longicaudatum Stoller is shown to be a synonym of L. elrodii Packard, and four new subspecies of L. elrodii are described from caves in eastern United States. The other species of the genus and the general trend towards cave adaptation among the species and subspecies are discussed. Three common species not adapted to caves were also encountered in the caves.

(1873). On the occurrence of Ligidium agile in Belgium. Annals and Magazine of Natural History: Vol. 12, No. 67, pp. 75-75.