Revision of the Neotropical Scleropactidae (Crustacea: Oniscidea)

The species of Scleropactidae from America are revised and redescribed. A phylogeny hypothesis based on an analysis of morphological characters is presented. The genera are redefined and the generic placement of several species is corrected. The Neotropical Scleropactidae include Colomboscia , Scleropactes , Circoniscus , Neosanfilippia , Sphaeroniscus , Richardsoniscus , Spherarmadillo , Colomboniscus , Amazoniscus and Protosphaeroniscus . The genus Chileoniscus is excluded from the Scleropactidae. Sphaerobathytropa is excluded from the Scleropactidae and its previous record from Argentina is revealed to be erroneous. Synuropus is revalidated and excluded from the Scleropactidae. The following new genera are introduced: Scleropactoides gen. nov. , Globopactes gen. nov. , Caecopactes gen. nov. , and Troglopactes gen. nov. Thirteen species are described as new: Caecopactes minimus sp. nov. , Colomboscia parva sp. nov. , Globopactes falconensis sp. nov. , Globopactes hispidus sp. nov. , Globopactes meridae sp. nov. , Scleropactes cotopaxii sp. nov. , Scleropactes ecuadoriensis sp. nov. , Scleropactes pululahua sp. nov. , Scleropactoides curvatus sp. nov. , Circoniscus hirsutus sp. nov. , Sphaeroniscus quintus sp. nov. , Spherarmadillo nebulosus sp. nov. , and Chileoniscus armadillidioides sp. nov. Identification keys to all species are provided.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 151 (Suppl. 1), 1–339.     

The origin of terrestrial isopods (Crustacea: Isopoda: Oniscidea)

Living isopods of the suborder Oniscidea (commonly called woodlice) are the only group of Crustacea almost entirely composed of terrestrial forms. Furthermore, woodlice are completely independent from the aquatic environment from which they originally arose. From marine ancestors, woodlice are a key taxon to study the conquest of the land among arthropods because of their interesting gradation of morphological, physiological and behavioral adaptations for terrestriality. However, the origin and evolution of this model group are still poorly known. Herein, we provide a synthesis of the oniscidean fossil record to replace this group in a deep-time context. Because members of the Oniscidea are difficult to fossilize, their fossil record alone is undoubtedly fragmentary and not representative of their complete evolutionary history, but it maintains an important relevance by providing reference points. To date, the first attested occurrences of Oniscidea are recorded from the Early Cretaceous. At this time, woodlice were already widely distributed (from Western Europe to Eastern Asia) with several species. By evaluating phylogenetic studies, palaeobiogeographic context of fossil specimens and current biological considerations, we discuss and support a pre-Pangaean origin of the Oniscidea, in the Late Paleozoic—most likely during the Carboniferous.     

Biology and population dynamics of Porcellionides sexfasciatus (Crustacea,Isopoda, Oniscidea)

The biology and the population dynamics of Porcellionides sexfasciatus Budde-Lund (1879) were studied on a field and carried out at Garat Naam (Kasserine, Tunisia) from July 1996 to June 1998. The reproduction exhibited a seasonal pattern extending from February/March to October/November. The juveniles appeared in the population from April to November. Size frequency distributions were analysed and 14 cohorts were recognised during the sampling period. Six cohorts were identified at the first sampling and eight new ones on the other samplings. Among these latter cohorts, three were tracked till they disappeared. Minimum average length of new cohorts ranged from 3.07 +/- 0.35 mm to 3.47 +/- 0.2 mm. Maximum average length of cohorts was 10.42 mm. P. sexfasciatus is a semi-annual species (females producing two or three broods per year), with iteroparous and amphogenes females (females reproducing twice or more in their life and producing both males and females), and bivoltine life cycle (two generations per year). The females are able to produce two broods, in the laboratory, without new mating. Fecundity and fertility, corresponding to the number of eggs or embryos per brood, appeared positively correlated with females' size. Although oscillating throughout the year, the sex ratio was often in equilibrium.     

Biogeography of body size in terrestrial isopods (Crustacea: Oniscidea)

This study tries to unveil the contribution of climatic shift in shaping the extreme body size diversity in terrestrial isopods (Oniscidea). Trying to explain size variation at an interspecific level, we test five hypotheses: (1) Bergmann's Rule and the temperature‐size rule postulate large size in cold areas; (2) The metabolic cold adaptation theory postulates small animal sizes in cold environments; (3) The primary productivity hypothesis predicts size increase in resource‐rich areas; (4) The aridity resistance hypothesis predicts large size in arid regions; and (5). The acidosis hypothesis predicts smaller size with decreasing soil pH. Globally, Bergmann's rule and the aridity hypothesis are weakly supported. Among families and genera, results are variable and idiosyncratic. Conglobating species sizes provide weak support for the acidosis hypothesis. Overall, size is strongly affected by familial affiliation. Isopod size evolution seems to be mainly affected by phylogenetically constrained life‐history traits.     

Revision of the genus Exalloniscus Stebbing, 1911 (Crustacea: Isopoda: Oniscidea)

The present taxonomic revision recognizes 16 species of Exalloniscus. Seven species, namely E. maschwitzi, E, caudatvs, E. malaccensis, E. bicoloratus from West Malaysia, E. bomeanus from East Malaysia, E. beroni from northern Thailand and E. vietnamensis from Vietnam, are described as new. Lectotypes off. coecus (Dollfus, 1898) and E. albus (Dollfus, 1898) are designated. Diagnostic characters of all the species are illustrated. A map and comments on the distribution and biology of the 16 species are included.     

Terrestrial isopods (Crustacea: Isopoda: Oniscidea) from Brazilian caves

To date, six species of terrestrial isopods were known from Brazilian caves, but only four could be classified as troglobites. This article deals with material of Oniscidea collected in many Brazilian karst caves in the states of Pará, Bahia, Minas Gerais, Mato Grosso do Sul, and São Paulo, and deposited in the collections of the Museu de Zoologia, Universidade de São Paulo, the Coleção de Carcinologia do Departamento de Zoologia, Universidade Federal do Rio Grande do Sul, and the collection of the Natural History Museum, Section of Zoology ‘La Specola’, Florence. Three new genera have been recognized: Spelunconiscus gen. nov. and Xangoniscus gen. nov. (Styloniscidae), and Leonardoscia gen. nov. (Philosciidae). Twenty‐two species have been identified, 11 of which in the families Styloniscidae, Philosciidae, Scleropactidae, Plathyartridae, Dubioniscidae, and Armadillidae are new to science: Leonardoscia hassalli sp. nov., Metaprosekia quadriocellata sp. nov. , Metaprosekia caupe sp. nov. , Amazoniscus leistikowi sp. nov. , Novamundoniscus altamiraensis sp. nov. , Trichorhina yiara sp. nov. , Trichorhina curupira sp. nov. , and Ctenorillo ferrarai sp. nov. from Pará; Xangoniscus aganju sp. nov. from Bahia; and Spelunconiscus castroi sp. nov. and Trichorhina anhanguera sp. nov. from Minas Gerais. Four new species in the families Styloniscidae ( Spelunconiscus castroi sp. nov. and Xangoniscus aganju sp. nov. ), Philosciidae ( Leonardoscia hassalli sp. nov. ), and Scleropactidae ( Amazoniscus leistikowi sp. nov. ) with highly troglomorphic traits can be considered as troglobitic, whereas all the remaining species are either troglophilic or accidentals. Brazilian caves are now under potential threat because of recent legislation, and the knowledge of the subterranean biodiversity of the country is thus of primary importance. © 2014 The Linnean Society of London     

Ultrastructure of CaCO3 deposits of terrestrial isopods (Crustacea, Oniscidea)

 The ultrastructure of the sternal CaCO₃ deposits of 3 species of the Diplochaeta and 15 of the Crinochaeta was investigated by means of scanning electron microscopy of fractured surfaces. In the Diplochaeta Li-gia italica and L. oceanica, the deposits consist exclusively of individual spherules with diameters between 0.2 and 1.4 μm. No material was observed within the spaces between the spherules. In Ligidium hypnorum, two structurally distinct regions exist. A proximal layer resembling the deposit of Ligia italica and L. oceanica and a distal layer in which the spherules appear to be fused with each other. In the species of the Crinochaeta, the CaCO₃ deposits comprise a spherular region which resembles the deposits of Ligidium hypnorum, and a homogeneous layer located between the spherular part of the deposit and the hypodermal cell layer. In some species the diameters of the spherules may be up to 3.1 μm. In the homogeneous layer and the distal spherular layer more calcium per volume can be stored than in the proximal spherular layer in which the spaces between the spherules are devoid of CaCO₃. This suggests that the multiple layered deposits are an adaptation to terrestrial life, as a consequence of the need for increased resorption of cuticular calcium. Accepted: 7 January 1997     

Taxonomic revision of the subfamily Toradjiinae (Crustacea: Oniscidea: Scleropactidae)

In the present revision four genera and 32 species are recognized. One genus, Paratoradjia , and 17 species, namely Adinda malaccensis, A. sumatrana, A. palniensis, A. carli, A. nilgiriensis, A. lobata, A. triangulifera, A. rudeli, A. lamellata, Protoradjia paeninsulae, P. insularis, P. montana, P. pilosa, Paratoradjia beroni, P. vietnamensis, P. sulcata and Toradjia hirsute , are described as new. The neotype of Toradjia cephalka and lectotypes of Adinda weberi, Protoradjia jacobsoni, Toradjia gorgona and T. celebensis are established. Adinda cahgarii is considered to be a junior synonym of Adinda weberi , and A. conglobator , a species inquirenda. Toradjia dollfusi is transferred to the genus Adinda , and T. indosinensis to Paratoradjia. The characters of the group and its taxonomic position within the Oniscidea are discussed: it is transferred from the Eubelidae to the Scleropactidae, of which it constitutes a separate subfamily, the Toradjiinae. A map and comments on the distribution of genera and species are included.     

潮虫亚目(甲壳动物亚门:等足目)二中国新纪录种

通过对山西省境内等足目进行调查研究,发现等足目潮虫亚目鼠妇科腊鼠妇属2个新纪录种,分别为多变腊鼠妇Porcellionides variabilis Jackson,1926和弗罗里达腊鼠妇Porcellionides floria Garthwaite&Sassaman,1985.多变腊鼠妇主要鉴别特征为体色各部分颜色多变,雄性第1腹肢的外肢节近鳃盖状,下端具一弧形凹陷,上端具波浪状凹刻;弗罗里达腊鼠妇主要鉴别特征为头胸部近似长方形,第7胸肢座节末端具2枚硬刺.所有检视标本保存于山西师范大学生命科学学院动物实验室.     

Old Aegean palaeoevents driving the diversification of an endemic isopod species (Oniscidea,Trachelipodidae)

The Greek endemic isopod species Trachelipus aegaeus is distributed in Aegean islands and the adjacent coastal parts of the Greek mainland. Major palaeogeographic events of the Aegean archipelago, such as the formation of the mid‐Aegean trench and the Messinian Salinity Crisis, have been often employed as major causal factors of evolutionary events and phylogeographic patterns exhibited by several taxa. Herein, we infer phylogenetic relationships among T. aegaeus populations using partial cytochrome oxidase subunit I (COI) and 16S rRNA sequences. Due to the poor preservation of the specimens, we propose a modified DNA extraction protocol, which returned highly positive results in terms of the quality of the total extracted DNA. We implement a calibrated molecular clock and path sampling analysis, using alternative palaeogeographic events and rates of substitution, to evaluate the biogeographic history of the species and to estimate the chronology of diversification events among its populations. Our results are clearly in favour of the scenario of the MAT triggering vicariance among most T. aegaus populations. Moreover, the large intraspecific genetic divergence (0–19% for COI and 0–20.3% for the 16S rRNA) and the overall phylogeographic patterns depicted herein seem not to have been obscured by more recent palaeogeological events. A role of dispersal, probably human‐aided, is assumed for certain ‘deviant’ cases.     

Phenetic analysis of populations of Porcellionides pruinosus (Brandt, 1833) (Crustacea, Isopoda, Oniscidea)

The cosmopolitan species, Porcellionides pruinosus (Brandt, 1833), exhibited a geographical variation of its morphological features and its reproduction pattern. In fact, some Tunisian populations had a seasonal reproductive period and other ones showed a reproductive activity. A phenetic analysis has been performed to compare populations belonging to P. pruinosus from different geographical localities. For this, nineteen quantitative characters in 800 specimens of P. pruinosus issued from nine populations located in the North, the Centre, and the South of Tunisia, and one population from Athens (Greece) were studied. These populations were characterized by different reproductive behaviours. The populations of Tabarka, Korba, and Tamerza showed reproductive activity, whereas those of Garat Naam, Raccada, Sahline, Gafsa, Rdayef, Gabès, and Athens exhibited a seasonal reproductive period. The variability of the first three axes of the principal components analysis (PCA) and their significance showed an intraspecific variability structure. The graphical representation of the population's dispersion generated by the two first axes (63.55% of the total variability) revealed a great heterogeneity among females of the different populations of P. pruinosus. The Garat Naam population was set apart from the other ones by its cephalic width and length and also by its apophysis length. Furthermore, cephalic and uropod length separated the Garat Naam and Tabarka populations. The dendrogram, based on Euclidean coordinates, confirms an isolation of the populations of Tabarka and Garat Naam, exhibiting respectively reproductive activity and seasonal reproduction. However, the other populations do not show any relationship with the reproduction behaviour. They were clustered in two groups. The first one is represented by the populations of the Southeast and the West of Tunisia. The second pooled the populations of the Northeast and the Centre of Tunisia with the population of Athens (Greece). Phenetic analysis of Tunisian populations exhibits an important heterogeneity, which is worth noting. Thus, we need to complete and deepen this study by genetic analysis and crossbreeding tests in order to define the taxonomic status of these populations.     

Description of the postmarsupial manca stages of Armadillidium granulatum (Crustacea,Isopoda, Oniscidea)

The development of the postmarsupial manca stages of Armadillidium granulatum Brandt, 1833 was studied in detail by morphological analysis. Ovigerous females were reared separately under controlled conditions, allowing us to follow the stages of development from release from the marsupium until the appearance of the first juvenile stage, identified by the full development of the seventh pair of pereopods. Each newborn was followed to record the subsequent moults that identify the three postmarsupial manca stages. Manca stage M I had a mean duration of 6 h, manca stage M II 15 days, and manca stage M III 32 days. The cephalothorax width was measured to provide a growth measure for each stage. The mean values of the cephalothorax width were: 0.512 mm (± 0.083 SD) for M I, 0.677 mm (± 0.058 SD) for M II and 1.194 mm (± 0.079 SD) for M III. The morphological modifications in the three postmarsupial manca stages were described, the body parts illustrated, and SEM images taken. The distinguishing characteristics among mancas were discussed, and comparisons made with manca stages of other terrestrial isopod species.     

Histological studies on the marsupium of two terrestrial isopods (Crustacea,Isopoda, Oniscidea)

The marsupium, a brood pouch in peracarid crustaceans (Crustacea, Malacostraca) has evolved in terrestrial environment for providing nutrition and optimal conditions for embryogenesis. In the present study we give details on the histology and ultrastructure of its constituting elements such as oostegites and cotyledons. Marsupia of two different eco-morphological types of woodlice, namely the non-conglobating species Trachelipus rathkii Brandt, 1833 and the conglobating species Cylisticus convexus De Geer, 1778 were investigated. Light microscopic (LM) studies showed some differences in the main structure of the two species’ brood pouch: in Trachelipus rathkii, a ‘clinger’ type woodlice, the oostegites bend outwards during brood incubation as growing offspring require more space, while in Cylisticus convexus, a ‘roller’ type isopod, the sternites arch into the body cavity to ensure space for developing offspring and still allowing conglobation of the gravid females. The quantitative analysis of the oostegites’ cuticle proved that the outer part is about 2.5 - 3 times thicker compared to the inner part in both species. Electron microscopic (TEM) examinations show only small histological differences in the oostegites and cotyledon structure of the two species. Cellular elements and moderately electron dense fleecy precipitate are found in the hemolymph space between the two cuticles of oostegites. The cells contain PAS positive polysaccharide areas. TEM studies revealed some differences in the cotyledon ultrastructure of the two species. Cotyledons of Trachelipus rathkii consist of cells with cristate mitochondria and granular endoplasmic reticulum with cisterns. Cotyledons of Cylisticus convexus consist of cells with densely cristate mitochondria and ribosomes attached to vesicular membrane structures. In both species cells with electron dense bodies were observed. We conclude that - besides the differences in marsupial shapes - the fine structure of the oostegites and cotyledons is hardly affected by the eco-morphological type, specifically the conglobating or non-conglobating character of the studied species.     

Small scale gradient effects on isopods (Crustacea: Oniscidea) in karstic sinkholes

We studied abundance and diversity patterns of terrestrial isopod assemblages along a ‘micro-scale’ vertical gradient in sinkholes in the Aggtelek National Park, Hungary. Time restricted manual sampling yielded ten native species, including endemic and rare ones. Along the gradient we found no major differences in species richness and -composition, and abundance decreased from the bottoms to the upper zones of the sinkholes. Species specific habitat preference on a vertical gradient showed two distinct groups by indicator species analysis: occurrence of habitat “generalists” was irrespective of vertical zones while “specialists” were restricted to the bottoms of the dolines. The latter group is formed mainly by rare species. We found that both diversity and evenness of isopod assemblages were highest in the bottom zone. Our results draw the attention to the significance of such common, yet undiscovered surficial depressions that can provide shelters for rare and specialist species and can provide shelter for survival of populations under changing climatic conditions.     

High cryptic diversity and persistent lineage segregation in endemic Romecytheridea (Crustacea,Ostracoda) from the ancient Lake Tanganyika (East Africa)

Ostracods form a substantial part of the endemic fauna of ancient lakes. Here, we have investigated the phylogenetic and phylogeographic patterns and genetic diversities of species of the endemic genus Romecytheridea from the Southern and Central part of Lake Tanganyika. We found that ostracod populations from four different localities are genetically highly differentiated from each other when analyzing the mitochondrial 16S region, while they are almost identical with genetic markers from the nuclear genome (D1-D2 from the large ribosomal subunit (LSU) and ITS). The criteria of the K/θ method for the evolutionary species concepts are fulfilled when analyzing 16S DNA sequence data, indicating that these populations are in fact different (cryptic) species with allopatric distribution. We discuss various hypotheses on how this high diversity could have originated. The complete lineage segregation can partly be explained by geographic isolation during periods of low lake level stands. But, other factors must have contributed to genetic isolation and speciation, as the two closest populations (Chimba and Katoto) from shallow parts of the Southern basin of Tanganyika are also geographically fully segregated.     

Female genitalia,reproductive cycle and sperm storage in Armadillidium vulgare (Crustacea,Isopoda, Oniscidea)

Light and electron microscopic studies that we have published in the past have reported many aspects of the reproductive process in Armadillidium vulgare with particular emphasis on the reconstruction of female genitalia. Together this body of work provides an almost complete, albeit fragmented picture of these processes and include many data on sperm storage and sperm translocation. Females of A. vulgare have a pair of cuticular genitalia in the lumen of the oviduct. For insemination, these genitalia can receive the copulatory organs of males formed by the elongated tips of the first two pleon endopods. During transitions between reproductive (parturial) and non-reproductive (normal, non-parturial) moult cycles the genitalia undergo intriguing structural changes resulting in two types of genitalia. Throughout their reproductive lifetime, either type is reconstructed after each moult depending on the reproductive phase of the female. In this review, we integrate the events that occur during a reproductive cycle with particular emphasis on the genitalia reconstruction and sperm storage, and discuss functional aspects of the genitalia. Thereby, we provide a case model that can be useful for further studies on genitalia diversity and female reproductive strategies in terrestrial isopods.     

Revision of the European species of the genus Trachelipus Budde-Lund, 1908 (Crustacea: Isopoda: Oniscidea)

The European species of Trachelipus Budde-Lund, 1908 are revised. The generic diagnosis is extended. The species T. aegaeus (Verhoeff, 1907), T. arcuatus (Budde-Lund, 1885), T. ater (Budde-Lund, 1896), T. camerani (Tua, 1900), T. dijfkilis (Radu, 1950), T. nodulosus (C. L. Koch, 1838), T. palustris (Strouhal, 1936), T. rathkii (Brandt, 1833), T. ratzeburgii (Brandt, 1833), T. razzautii (Arcangeli, 1913), T. rhinoceros (Budde-Lund, 1885), T. squamuliger (Verhoeff, 1907), T. trilobatus (Stein, 1859), (77 troglobius Tabacaru & Boghean, 1989) and 7T vespertilio (Budde-Lund, 1896) are recognized as valid. Except for T. troglobius , redesriptions, figures and distribution maps are given. A key to species is provided. Nineteen names are new synonyms of the above mentioned ones; nine names become nomina dubia.     

Intraspecific variation in the terrestrial isopod Oniscus asellus Linnaeus, 1758 (Crustacea: Isopoda: Oniscidea)

A study of intraspecific variation in one of the most widespread and abundant terrestrial isopods in Europe, Oniscus asellus , is presented. It is concluded that previous attempts to describe intraspecific taxa in this species are invalid, but that the species is clearly divisible into two subspecies which differ in a number of features, including male sexual modifications. The nominal subspecies, Oniscus asellus asellus Linnaeus, 1758, is described in detail, and a neotype, collected from Uppsala, Sweden, where Linnaeus lived and worked, is designated. Oniscus asellus occidentalis ssp. nov . is also described, and reported as occurring in the far west of the species' range, in the British Isles, Ireland and France. Characters useful in distinguishing these two taxa are indicated and figured. Differences in the ecology of the two taxa are also noted, occidentalis appearing to be a relict Atlantic taxon, largely restricted to damp woodland. The existence of populations intermediate between asellus and occidentalis is noted, and the features of these populations discussed in detail. A combination of geographical, environmental and laboratory breeding data suggest that these intermediates arise through hybridization between the two subspecies, this process of hybridization being accelerated by human activity, which brings the two taxa into frequent contact. It is suggested that Oniscus asellus may provide an excellent model system for the study of the dynamics of hybrid zones.     

Eco-morphological studies on pleopodal lungs and cuticle in Armadillidium species (Crustacea,Isopoda, Oniscidea)

Terrestrial isopods (Crustacea, Isopoda, Oniscidea) have adapted to land life by diverse morphological, physiological and behavioral changes. Woodlice species exhibit a large variety in this respect, their preferences ranging from moist to dry habitats. These moisture preference values are related to various morphological adaptations, rendering terrestrial isopods amenable to studying morphological adaptations to terrestrial life. We performed a comparison of four Armadillidium species (Armadillidium zenckeri, Armadillidium nasatum, Armadillidium versicolor, Armadillidium vulgare), by quantifying two morphological traits: the extent of the interfacial endothelium between the respiratory space and the hemolymph within pleopodal lungs and the thickness of tergite cuticle, which are ‘key factors’ in determining protection from desiccation. These values were measured from light micrographs of cross-sectioned lungs. The cosmopolitan A. vulgare, as a habitat generalist, seems to be the most resistant against desiccation and other environmental conditions, while A. zenckeri is the most sensitive one. Light microscopic studies revealed that the four species can be ordered similarly, if we compare them by the extension of the endothelial interface and cuticle thickness, suggesting that these morphological traits are important determinants of their distribution on habitat, microhabitat scales and through the existence of suitable habitats – together with many other factors – the geographical pattern of species occurence.