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An overview of the Estonian terrestrial isopod fauna is given, based on literature data and material collected from 1984 to 2021. The identified material consisted of 10915 specimens belonging to 14 species and collected from 172 localities throughout Estonia. In combination with previous data from the literature data, there are now reliable records of 16 species of woodlice from Estonia. Two species, viz. Platyarthrus hoffmannseggii Brandt, 1833 and Hyloniscus riparius (C. Koch, 1838), are new for the fauna. The latter has probably colonised Estonia recently and range expansions have been reported elsewhere. The data on Philoscia muscorum (Scopoli, 1763) are dubious, and this species is currently excluded from the Estonian list.

[EN] Terrestrial isopods (Crustacea: Oniscidea) are a model group for studying the colonization of land. However, their fossil record is remarkably scarce and restricted to amber inclusions, and therefore amber deposits represent valuable windows to their past diversity and morphology. Here we present a new collection of 11 terrestrial isopod specimens preserved in Albian-aged amber from the Peñacerrada I outcrop, northern Spain, which collectively represent the most thoroughly documented fauna of Mesozoic Oniscidea. The three new genera and species identified belong to three of five major groups of the Oniscidea: Eoligiiscus tarraconensis, new genus and species (Ligiidae), Autrigoniscus resinicola, new genus and species (Synocheta: Trichoniscidae), and Heraclitus helenae, new genus and species (Crinocheta: Detonidae?). These taxa significantly expand the known fossil record of Oniscidea and demonstrate that considerable cladogenesis had already transpired by the Albian. The assemblage represents the earliest-known diversification of Oniscidea, extending direct evidence of terrestrialization in the group back to the late Early Cretaceous. These new taxa exhibit some characteristics that may inform hypotheses relating to general patterns of terrestrial isopod evolution. A discussion is provided about different aspects of the paleoecology and biology of the fossils compared to the Recent fauna. The new species indicate that Cretaceous isopods were a group of considerable adaptive diversity, exhibiting innovations analogous to what Recent isopods would exhibit 105 million years later., A.S.-G. is funded by an APOSTD2019 Research Fellowship from the Generalitat Valenciana and the European Social Fund (ESF). This study is a contribution to the Spanish AEI/FEDER, UE Project CRE (CGL2017-84419).

The presence of the Spotless Starling in Sicily was reported for the first time at the beginning of the XIX century, although the first nests for the province of Trapani are reported almost at the end of the XX century. As a breeder, the Spotless Starling remained absent from all the circumsicilian islands until the first report for the island of Pantelleria, in 2012. In 2020, the nest of Spotless Starling was observed on the island of Favignana, within a hole on an antenna. The couple fed the chicks with Ligia italica crustacean isopod of the family Ligiidae. The nesting on the island of Favignana confirms the continuous expansion of the species in Sicily.

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.

Recent phylogeographic studies along the coastline of southern Africa have uncovered cryptic diversity in several coastal invertebrates, including direct developing crustaceans in the superorder Peracarida. These findings indicating the possible existence of additional cryptic diversity in other yet to be studied peracarids, particularly those known to harbor said cryptic diversity in other regions of the world. Isopods in the genusLigiaare one such taxon. They inhabit patchy rocky beaches, are direct developers, avoid the open water, and exhibit other biological traits that severely constrain their dispersal potential (e.g., poor desiccation resistance). These traits are thought to have led to long-term isolation of populations, and allopatric diversification inLigiaspecies around the world; however,Ligiaspecies in southern Africa, where three endemicLigiaspecies of uncertain validity are known to exist, remain unstudied to date. In this study, we used mitochondrial and nuclear markers to characterizeLigiacollected in 18 localities from Namibia to the KwaZulu-Natal region of South Africa. We report the presence of cryptic lineages withinLigiaspecies in the region that suggest the need for taxonomic reevaluation of these isopod species.

Nine species of terrestrial isopods are reported for the Polynesian island of Rapa Nui (Easter Island) based upon museum materials and recent collections from field sampling. Most of these animals are non-native species, but two are new to science: Styloniscus manuvaka sp. n. and Hawaiioscia rapui sp. n. Of these, the former is believed to be a Polynesian endemic as it has been recorded from Rapa Iti, Austral Islands, while the latter is identified as a Rapa Nui island endemic. Both of these new species are considered ‘disturbance relicts’ and appear restricted to the cave environment on Rapa Nui. A short key to all the oniscidean species presently recorded from Rapa Nui is provided. We also offered conservation and management recommendations for the two new isopod species.

Thirty-four species of terrestrial isopods (Crustacea: Oniscidea) from the Oued Laou basin, in the Rif area of north-eastern Morocco, are recorded. One genus (Paractenoscia) and seven species (Trichoniscus microphthalmus, Paractenoscia cavernicola, Bathytropa rifensis, Soteriscus gibbosus, S. laouensis, Porcellio pseudornatus, and Eluma praticola) are described as new. The genus Soteriscus, unavailable according to article 13.3 of the International Commission on Zoological Nomenclature (ICZN), is here revalidated by choosing S. gaditanus as type species. Six species (Graeconiscus thermophilus, Ctenoscia minima, Platyarthrus parisii, Porcellio humberti, Porcellio flavocinctus and Eluma caelata) have been fully illustrated to facilitate their identifications. Ctenoscia dorsalis Verhoeff is considered to be a junior synonym of C. minima Dollfus. Porcellio ornatus from southern Spain is also figured for comparison with P. pseudornatus sp. nov. The composition and origin of the oniscidean fauna of the Rif region is briefly discussed.

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.

The extensive coastlines of South Africa and Namibia extends from the Atlantic to the Indian Ocean and encompass several major biogeographic provinces, each characterized by unique faunal and floral assemblages. Recent biogeographic studies have led to competing biogeographic models of the southern African coastline. This has stimulated phylogeographic work to determine whether the distribution of genetic diversity within coastal invertebrate species match the proposed biogeographic regions. The lack of congruence between studies and the discovery of cryptic diversity indicating the possible existence of cryptic species in coastal isopods in the region underscore the need for additional phylogeographic research in southern Africa, particularly for organisms that have been shown to both harbor cryptic diversity and to retain signatures of past geological and oceanographic processes in their phylogeographic patterns. Isopods in the genus Ligia exhibit several biological traits that suggest they may be informative on phylogeographic patterns. They inhabit patchy rocky beaches, are direct developers, avoid the open water, and exhibit several biological traits that severely constrain their dispersal potential (e.g. poor desiccation resistance). These traits are thought to lead to long term isolation of populations, the retention of geological and oceanographic signatures in phylogeographic patterns of Ligia, and the presence of cryptic lineages. In this study, we used mitochondrial and nuclear markers to characterize Ligia collected in 18 localities across Namibia to the KwaZulu-Natal region of South Africa. We report the presence of cryptic lineages within Ligia species in the region, as well as distributional patterns that differ from those reported from other coastal taxa, but that broadly matches a widely used biogeographic model for the region.

Ligia isopods are conspicuous inhabitants of rocky intertidal habitats exhibiting several biological traits that severely limit their dispersal potential. Their presence in patchy habitats and low vagility may lead to long term isolation, allopatric isolation and possible cryptic speciation. Indeed, various species of Ligia have been suggested to represent instead cryptic species complexes. Past studies; however, have largely focused in Eastern Pacific and Atlantic species of Ligia, leaving in doubt whether cryptic diversity occurs in other highly biodiverse areas. The Seychelles consists of 115 islands of different ages and geological origins spread across the western Indian Ocean. They are well known for their rich biodiversity with recent reports of cryptic species in terrestrial Seychellois organisms. Despite these studies, it is unclear whether coastal invertebrates from the Seychelles harbor any cryptic diversity. In this study, we examined patterns of genetic diversity and isolation within Ligia isopods across the Seychelles archipelago by characterizing individuals from locations across both inner and outer islands of the Seychelles using mitochondrial and nuclear markers. We report the presence of highly divergent lineages of independent origin. At Aldabra Atoll, we uncovered a lineage closely related to the Ligia vitiensis cryptic species complex. Within the inner islands of Cousine, Silhouette, and Mahé we detected the presence of two moderately divergent and geographically disjunct lineages most closely related to Ligia dentipes. Our findings suggest that the Seychelles may harbor at least three novel species of Ligia in need of description and that these species may have originated independently.

Past phylogeographic work has shown Ligia hawaiensis, a coastal isopod species endemic to the Hawaiian Islands, to be a paraphyletic complex of several highly genetically divergent yet morphologically cryptic lineages. Despite the need for a taxonomic revision of this species, the lack of morphological differentiation has proven an impediment to formally describe new Ligia species in the region. Molecular characters and species delimitation approaches have been successfully used to formally describe cryptic species in other crustacean taxa, suggesting they may aid taxonomic revisions of L. hawaiensis. Herein, various distance- and tree-based molecular species delimitation approaches are applied on a concatenated dataset comprised of both mitochondrial and nuclear gene sequences of L. hawaiensis and L. perkinsi, a terrestrial species endemic to the Hawaiian archipelago. Results of these analyses informed a taxonomic revision leading to the redescription of L. hawaiensis and the description of seven new cryptic species on the basis of molecular characters: L. dante, L. eleluensis, L. honu, L. kamehameha, L. mauinuiensis, L. pele, and L. rolliensis. These coastal Ligia species from the Hawaiian archipelago appear to be largely limited to single islands, where they appear largely constrained to volcanic rift zones suggesting allopatric events at local scales may drive diversification for poorly dispersing organisms in the Hawaiian coastlines. Additional work remains needed to fully assess the role of said events; however, the description of these novel species underscore their potential to aid in studies of local diversification of marine organisms in Hawai‘i. Lastly, this represents the first application of molecular taxonomic approaches to formally describe genetic lineages found in Ligia isopods as species, underscoring the promise these methods hold to taxonomic revisions in other species in the genus shown to harbor cryptic genetic lineages.

The morphological traits and mitochondrial genes of sympatric sea slaters from the genus Ligia were analysed from samples collected along northeastern coastal China and adjacent coastal East Asia to assign the species and to obtain interpretations of their distributions. Using 338 sequences and 199 diagnoses of 16S polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) from 331 specimens sampled from 26 localities, and homological sequences from counterparts from South Korea and the west coast of the USA, we assigned these taxa into two distinct species, Ligia exotica and Ligia cinerascens. Both species are recovered as two monophyletic clades in the robust phylogenetic hypothesis presented here. The northern boundaries of these species in China and the Korean peninsula are more southern than those of counterparts in Japan. Ligia exotica in northeastern coastal China is further split into two geographical subclades (B1 and B2), coexisting near 35°N. The distribution range of L. cinerascens covers the whole range of L. exotica subclade B1. Counterparts in Japan show a similar pattern. Oceanic rafting, shipping, damming and planting of seaweed are proposed as the media for the contemporary connectivity among populations of Ligia species inhabiting coastal China. © 2013 The Linnean Society of London

The genetic diversity and historical demography of the high intertidal isopod Ligia pallasii Brandt, 1833 from the eastern Pacific were assessed using mitochondrial DNA (mtDNA) sequences from portions of the cytochrome c oxidase subunit I (COI) gene collected at 21 sites spanning more than 4000 km of coastline from the Aleutian Islands, Alaska to Central California. Most of the 86 haplotypes (92%) were unique to a sampling location, but the two most common haplotypes were shared across 1000’s of kilometers in the northern-most part of the distribution, where the lowest level of genetic diversity was found consistent with postglacial range expansion. Phylogenetic analysis revealed three moderately well-supported clades (N, C, S) separated by Cape Mendocino (40.0°N) and Point Arena (38.9°N). The three clades in Ligia pallasii were shallow compared to the deep divergences found in the congener “Ligia occidentalis” that is sympatric for part of the range, and maybe a cryptic species complex. The distribution of genetic diversity within L. pallasii as well as in all North American Ligia spp. examined to date follows a pattern of lower genetic divergence at higher latitudes. The observed pattern suggests that processes (gene flow, selection, and drift) that lead to genetic divergence may vary as a function of latitude.

The distribution, habitat and food preferences of two partially sympatric high intertidal isopods, Ligia pallasii and Ligia occidentalis, were investigated. A survey along the Eastern Pacific coast indicated species-specific site preferences as evidenced by a mosaic pattern of distribution with few sites of co-occurrence. Ligia pallasii preferred sites with rocky cliffs and caves that may provide a thermal refuge for the northern species, whereas L. occidentalis apparently is a habitat generalist of rocky shores. Differences in reproductive patterns exist: L. occidentalis reproduced once annually in spring and summer, but gravid females of L. pallasii were observed throughout the year. Feeding experiments did not indicate any significant differences in diets; both isopod species fed mainly on seaweed and diatoms but preferred rare protein sources when available.

Isopodos sao exemplos da transicao evolutiva dos crustaceos do mar para terra, existindo formas tipicamente aquaticas e formas tipicamente terrestres. Ligia exotica e dominante na regiao intertidal do Estuario da Lagoa dos Patos, tendo um importante papel na reciclagem de nutrientes e na cadeia trofica. A area de estudo compreendeu o Molhe Oeste de Rio Grande e a Ilha do Leonideo. O conteudo alimentar foi estudado sazonalmente, atraves da captura manual de individuos em Outubro/2003, Janeiro, Abril e Julho/2004. Após capturados, os individuos foram fixados imediatamente em formol 4% durante 24 horas e conservados em alcool 70%. Os tubos digestivos foram pesados e o grau de replecao foi estimado. O conteudo de cada tubo digestivo foi diluido em 1 ml de agua destilada. Para quantificacao dos itens, o conteudo foi colocado em uma lamina de contagem graduada. Cada item identificado foi quantificado pela contagem do numero de ocorrencia nos quadrados da lamina. Para testar a possivel diferenca entre a frequencia dos itens consumidos por machos e femeas, foi utilizado o quiquadrado. Analises qualiquantitativas foram realizadas segundo os metodos de frequencia relativa de ocorrencia, frequência relativa dos pontos. Um total de 912 tubos digestivos foi analisado: 426 individuos no Molhe Oeste e 485 individuos na Ilha do Leonideo. Seis itens alimentares foram identificados e diferencas significativas foram observadas nos itens consumidos por machos e femeas de ambas as populacoes. Os itens alimentares mais importantes para a dieta natural de Ligia exotica foram: detrito vegetal, areia e a alga Polysiphonia sp. Desta forma, em ambas as regioes do estuario, a especie pode ser considerada generalista. Isopods are examples of the evolutive transition of the crustaceans from sea to land, inhabiting aquatic and terrestrial environments. Ligia exotica is dominant in the intertidal region of the of Patos Lagoon estuary, playing an important role in recycling nutrients and in the trophic web as a whole. The study area was the West Breakwater of Rio Grande Channel and Leonideo Island. The natural diet was analyzed through standardized one hour manual sampling performed in October/2003, January, April and July/2004. After collected, individuals were immediately fixed in 4% formalin during 24 hours and conserved in 70% ethanol. The guts were weighted and repletion degree was estimated. Each gut content was diluted in 1 ml of distilled water. To quantify the items, content was placed in a graduated slide for counting. Each identified item was quantified by the number of occurrences in the slide squares. To test significant differences between the frequencies of items consumed by males and females, a chi-square test was used. Qualiquantitative analysis was performed following the method of relative frequency of occurrence and relative frequency of points. A total of 912 guts was analyzed: 426 individuals from the West Breakwater and 485 individuals from the Leonideo Island. Six food items were identified and significant differences were observed in the items consumed by males and females of both populations. The most important food items in the natural diet of Ligia exotica were: vegetal detritus, sand and the seaweed Polysiphonia sp. Thus, in both regions of the Estuary, the species can be considered generalist.

Nucleotide sequences from the cytochrome c oxidase subunit I (COI) gene were used to test for genetic differentiation in the rocky intertidal isopod crustacean, Ligia occidentalis (Ligiidae), from the eastern Pacific. Phylogenetic analyses showed that individuals of L. occidentalis from southern California, USA to Manzanillo, Colima, Mexico partitioned into 15 highly-divergent clades. Mean Kimura 2-parameter (K2P) genetic distances among clades ranged from 13.2% to 26.7%. These values are similar to interspecific genetic distances found in a wide variety of crustaceans, including Ligia spp., suggesting that the taxon L. occidentalis represents a complex of cryptic species.

The aim of this study was to estimate growth parameters of two populations of Ligia exotica inhabiting discrete estuarine areas of Patos Lagoon, Rio Grande do Sul, Brazil. Sampling was performed fortnightly at two different estuarine zones, named Leonideo Island and West Breakwater, to detect different growth patterns for this species by using the von Bertalanffy growth model (VBGM). The VBGM estimated were as follows: TLmm = 34.57 (1−e−0.012(t−2.93)) (males in Leonideo Island), TLmm = 35.61(1−e−0.009(t−5.87)) (males in West Breakwater), TLmm = 30.11(1−e−0.009(t−5.84)) (females in Leonideo Island) and TLmm = 29.65(1−e−0.01(t−4.87)). Significant sexual dimorphism was observed, since males reach larger TL (mm) by higher k value (day) and consequently a faster growth pattern. Different growth patterns of males were also detected comparing both populations, in such a way that the West Breakwater individuals are larger than those from the Leonideo Island. One possible explanation is the higher food availability observed in the former site, as well as favourable environmental parameters, providing better conditions for individual growth. Briefly, two different populations of L. exotica were detected in the studied area, presenting discrete growth parameters highly influenced by environmental factors.

Phylogeographic studies have provided valuable insights into the evolutionary histories and biodiversity of different groups in the Caribbean, a region that harbors exceptional terrestrial and marine biodiversity. Herein, we examined phylogeographic patterns of the poorly dispersing supralittoral isopod Ligia sampled from 35 localities in the Caribbean Sea and adjacent areas, as well as from Veracruz (Gulf of Mexico), the type locality of L. baudiniana (the only currently recognized native Ligia species in the Caribbean). We conducted Maximum Likelihood and Bayesian phylogenetic analyses of four mitochondrial genes (Cytb, 16S rDNA, 12S rDNA, and COI) and Parsimony analyses of one nuclear gene (NaK). We found a well-supported and highly divergent clade of Ligia that is distributed in the Caribbean Sea, Bahamas, southern Florida, Bermuda, and the Pacific coast of Central America and Colombia, but not in the Gulf of Mexico. A characteristic appendix masculina distinguishes this clade from other lineages of Ligia. Large divergences within this clade suggest that it constitutes a cryptic species complex. Genetically and morphologically, the specimens from the type locality of L. baudiniana were indistinguishable from the non-native species L. exotica. Some phylogeographic patterns of Ligia in the study area may be consistent with the proto-Antillean or GAARlandia vicariant hypotheses, but uncertainty concerning divergence times and aspects of the geological history precludes stronger biogeographical inferences. Passive overwater dispersal appears to have played an important role in shaping phylogeographic patterns of Ligia in the Caribbean Sea. These patterns, however, do not correspond with predicted biogeographic patterns based on population connectivity of marine organisms with larval dispersal, and do not reflect the southeast to northwest colonization pattern that has been proposed for the colonization of the Caribbean from South America by some terrestrial animals.

A new oniscoid, Ligia taiwanensis, from a mountain stream in southern Taiwan is described.

Isopods are a cosmopolitan group of crustaceans, which inhabit marine environments ranging from deep-sea to intertidal areas, surface and underground freshwaters and terrestrial environments fromhigh humidity to dry habitats, including deserts. More than one third of the described isopodan species (approximately 9000) belong to the terrestrial Oniscidea or woodlice (slaters, sowbugs and pillbugs; Schamlfuss 2003). The phylogeny and systematics of Oniscidea were analysed and presented by several authors (Schmalfuss 1989; Erhard 1998; Tabacaru and Danielopol 1999). In general, Oniscidea are assigned to five sections, namely Diplocheta, Tylida, Microcheta, Synocheta andCrinocheta, with 33 families altogether (Erhard 1998). Amphibious species of the family Ligiidae (slaters) and members of Mesoniscidae represent only approximately 50 of the described species, the rest belonging to the higher oniscideans,mostly to troglobiontic Synocheta and “truly terrestrial” Crinocheta. Terrestrial isopods are effective herbivorous scavengers feedingpredominantly on decayed plant material, fungi and algae, thus participating in decomposition and cycling of energy and organic matter in the terrestrial environments (Hopkin 1991; Zimmer and Topp 1997). Due to their significant ecological role and their ability to survive in polluted environments, a substantial amount of research was focused on these organisms, and as a result a comprehensive knowledge accumulated on their biology. Species like Porcellio scaber and Oniscus asellus, for example, are among the most studied organisms in terrestrial ecophysiology and ecotoxicology (Hopkin 1989; Drobne 1997). Terrestrial isopods have diverse feeding strategies including coprophagy and occasional cannibalism. The nutritional importance and significance of coprophagy in the field was not demonstrated

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.

Summary A comparative study of woodlice which show different degrees of fitness for terrestrial life provides information about the evolution of land faunas and underlines the significance of water relations in this respect. Species of woodlice differ as regards rates of transpiration and survival in dry air. They may be considered as physical bodies so far as the effects of temperature and humidity upon evaporation are concerned, and they probably lack an epicuticular wax. No simple relation has been found between those climatic factors which affect evaporation and period of survival; neither is it expected on theoretical grounds. Transpiration from the region of the pleopods is greater, per unit area, than from elsewhere. Pseudotracheae assist respiration in dry air. In moist air oxygen is absorbed through regions of the integument other than the pleopods; but such integumental respiration decreases in importance in more terrestrial species. The only adaptation to land as regards excretion is a general suppression (compared with aquatic isopods) of nitrogen metabolism. Uric acid in small quantities is retained in the tissues. The faeces are moist. The tegumental glands are not an important source of water loss. The pleopods are not moistened by glandular secretions. Desiccated woodlice can restore their original weight by absorption of moisture, by mouth and anus, from free water surfaces, and by mouth from moist surfaces, even though the ambient air is unsaturated. The higher forms possess external capillary channels which assist in irrigation of the pleopods. The osmotic pressure of the blood of Ligia oceanica is higher than that of sea water; that of the other species measured is somewhat lower. Osmotic regulation is possible for Ligia in dilute sea water down to 50%, but adaptation to land on the part of most woodlice seems to be secured by osmotic tolerance rather than regulation. Woodlice can withstand higher ambient temperatures, for short exposures, in air at 50% R.H. than in saturated air, and this is the result of rapid transpiration. In the field transpiration plays a significant part in determining body temperature, and may be of survival value during exposure to direct insolation. All species require saturated air or a moist substrate in their permanent habitats, and it is probable that they differ as regards tolerance of suboptimal conditions during wandering rather than dryness of the normal retreat. With this proviso the families which have been investigated stand substantially in the following order of increasing terrestrialness of habitat: Ligiidae, Trichoniscidae, Oniscidae, Porcel-lionidae, Armadillidiidae. They also stand approximately in the same order as regards various morphological and physiological specializations associated with life on land (Table 1). What success the group has achieved on land may be ascribed to avoidance of the rigours of true terrestrial conditions by means of behavioural mechanisms which retain them in the cryptozoic niche, rather than to morphological or physiological adaptations. Further information is needed along three lines: (i) precise microclimatic measurements linked with observations of behaviour in the field, (ii) laboratory analysis of orientation mechanisms, (iii) neurophysiological investigation of the sensory mechanisms involved. The geological age of the group is uncertain, but there were probably land-living oniscoids before the Tertiary. Their comparative lack of progress subsequently may be the result of retaining a water-permeable integument, which is necessary for cooling during brief exposures to high temperatures and also for respiration.