淫羊藿属植物形态分类性状评述

淫羊藿属是分类学上研究的热点和难点,其类群发表和修订均较频繁。为更清晰掌握淫羊藿属的性状变异,该文在查阅该属研究成果和标本的基础上,结合课题组野外调查和分析,对该属重要性状进行系统梳理。花瓣式样是淫羊藿属分类的最重要依据,但并非绝对稳定,种内花瓣形态可能存在丰富变异。花瓣颜色、花药颜色,甚至花的大小至少在部分类群中不宜作为分类的主要依据。根茎性状在多数类群中不失为一个有用的分类性状,但不能一概而论,应基于广泛调查。多数类群的花茎上叶的类型及小叶存在不同程度的变异,在实际应用中存在一定困难。非腺毛特征十分复杂,不同样本存在不同程度差异,不宜作为物种鉴别的关键依据。淫羊藿属植物栽培后植株普遍更矮小,提示开展自然生境下的调查和形态观测对掌握物种形态特征非常必要。中国淫羊藿属类群仍处于活跃进化中,其形态变异复杂,物种鉴定和资源利用时应足够谨慎。     

Three new species of deep‐sea Gromia (Protista,Rhizaria) from the bathyal and abyssal Weddell Sea,Antarctica

We describe three new species of the genus Gromia from bathyal and abyssal depths in the Weddell Sea. The new species are characterized by a combination of morphological and molecular criteria. All three species possess a distinct oral capsule and a layer of ‘honeycomb membranes’, which form the inner part of the organic test wall. Both these features are typical of gromiids. Their identification as gromiids is confirmed by analyses of partial small subunit ribosomal DNA (SSU rDNA) gene sequences. Gromia marmorea sp. nov. is a rounded species with a prominent oral capsule and a characteristically mottled appearance. In Gromia melinus sp. nov. , the test surface exhibits a polygonal pattern of ridges, with a layer of clay particles coating the surface between the ridges. Gromia winnetoui sp. nov. represents an elongate morphotype in which the organic test is enclosed within an agglutinated case, a feature previously unknown in gromiids. Phylogenetic analysis using the maximum‐likelihood method revealed that all three species form distinct clades, reflecting the morphological differences among Weddell Sea species, as well as between deep‐water Southern Ocean Gromia and previously described gromiids. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 157 , 451–469.     

Comparative seed morphology of Boronia and related genera (Boroniinae: Rutaceae) and its systematic implications

Comparative seed morphology of Boronia Sm., Boronella Baill., Neobyrnesia J. A. Armstr. and Zieria Sm., 31 taxa in total, in Rutaceae is studied. The seeds are ventrally ellipsoid to ovoid (0.93–4.42 × 0.50–2.31 × 0.95–2.70 mm). Colour is brown to black. An elaiosome which is related to myrmechocory was observed in Boronella, Boronia, Neobyrnesia and Zieria. Six testa surface pattern types are identified: Type I (Boronia sect. Boronia) – smooth, and cells not barely discernable; Type II (Boronella) – smooth and cells more or less rectangular and often cells elongated; Type III (Boronia sects. Boronia, Cyanothamnus, Imbricatae and Valvatae, Neobyrnesia) – colliculate with four subtypes by presence, absence of ridges or ridge characters; Type IV (Boronia sect. Alatae) – digit form; Type V (Boronia sect. Algidae) – alveolate; Type VI (Zieria) – ridged, the interridge area formed by both cells that form the ridges and cells that do not form the ridges. Seed morphology, especially testa surface patterns, was partially congruent with the current classification of Boronia, with most sections having apomorphies, and provided additional support for the placement of Boronella near Boronia sect. Boronia. Hilum (surrounded by labiose margin or not) and elaiosome shape also offer useful diagnostic characters for Boronia at infrageneric levels. Neobyrnesia and Zieria both had unique testa surface patterns. The seed morphological data contribute to our understanding of systematic relationship in the subtribe Boroniinae.     

Effects of environmental heterogeneity on species diversity and composition of terrestrial bryophyte assemblages in tropical montane forests of southern Ecuador

Background: Most studies on tropical bryophytes deal with epiphytic species. This is the first ecological study of tropical forests that focuses specifically on terrestrial bryophytes.

Aim: To investigate the differences between slope and ridge environments in upper montane forests of southern Ecuador in terms of species diversity (richness, abundance), species composition and life forms of terrestrial bryophytes.

Methods: We used Non-metric Multidimensional Scaling (NMDS) to group bryophyte relevés by study location, habitat type and exposure class. Species indicator values were calculated and compared for different habitats.

Results: In total, 140 species were recorded, the majority being liverworts. NMDS analyses and Mantel correlations clearly separated between slope and ridge relevés, and between sunny and shaded microhabitats on ridges. Bryophyte life forms also showed different distribution patterns in slope and in ridge habitats. Mosses were more prominent in sunny than in shaded microhabitats.

Conclusions: Environmental differentiation between ridges and slopes, and small-scale variation in microclimatic conditions caused by differences in exposure, were stronger predictors of species richness and composition than geographical distance between study sites.     

Palynological characters of Glycyrrhiza,Glycyrrhizopsis, and Meristotropis (Leguminosae), with special reference to their taxonomic significance

Abstract The pollen morphology of 11 species of the genus Glycyrrhiza L. with one from each of the genera Glycyrrhizopsis Boiss. & Bal. and Meristotropis Fisch. & C. A. Mey. was investigated by scanning electron microscopy. In pollen morphology, the main differences between Glycyrrhizopsis and Glycyrrhiza are: Glycyrrhizopsis—pollen grains 36.63 × 40.42 μm in size, oblate spheroidal in shape; and Glycyrrhiza—pollen grains 24.47–33.18 × 23.82–31.83 μm in size, prolate spheroidal in shape. Glycyrrhizopsis and Glycyrrhiza should be recognized as two distinct genera based on palynological and morphological characters. Meristotropis and Glycyrrhiza are similar in many important palynological and morphological characters, suggesting that the two should be merged. In Glycyrrhiza, two types of pollen grains, 3‐lobed‐circular or subtriangular in polar view, are found in different species, in accordance with morphological differences in the two groups, shedding light on the classification and evolution of the genus.     

Description, seasonal morphological variation, and molecular identification of Paraxanthus barbiger megalopae obtained from the natural environment

Larval identification represents a powerful tool for detailed studies on recruitment and population dynamics in marine invertebrates. However, intra-specific morphological variation can become a serious limitation for the correct identification at species level. High morphological variation can be expected in species with continuous breeding periods because larvae are exposed to seasonal fluctuations in physical and biological factors during their development in the plankton. We describe, for the first time, the megalopae of Paraxanthus barbiger, one of the most common and abundant brachyuran crabs along the coast of Chile. To validate larvae identification, the 16S rRNA gene was sequenced from both megalopae and adults, and was compared with sequences of three sympatric species. In addition, size, body shape, and appendage setation pattern variations were analyzed with a year-round sampling scheme. The results demonstrated high seasonal phenotypic plasticity in size. Despite these differences, certain conservative characteristics exist which can be very useful for identification at species level.     

Species‐dependent microarchitectural traits of iridescent scales in the triad taxa of Ornithoptera birdwing butterflies

Ornithoptera birdwing butterflies have blue, green, or orange iridescent scales in different species or subspecies. To understand the species‐ or subspecies‐dependent scale color differences, we performed comparative morphometric analyses of iridescent scales from three closely related taxa: O. priamus priamus (green), O. priamus urvillianus (blue), and O. croesus (orange). The three types of Ornithoptera wings exhibited reversible color changes to longer wavelengths with different kinetics upon immersion in methanol, suggesting that their color differences are at least partly based on differences in the size of air cavities made by nanostructures. Cover scales of all three color types were visually semi‐transparent glass scales that exhibited color when placed on a dark background. The dorsoventral differences in coloration were observed in single scales, suggesting the optical importance of scale surfaces. Scanning electron microscopy of cover scales in cross section revealed that all color types exhibited finely sculpted tapered ridges and thick, irregular basal multilayers containing tandemly clustered granular objects and air cavities. Scale thickness, ridge height, and multilayer thickness were significantly different among the three color types, and granular object size was significantly different between orange scales and blue and green scales. We conclude that each of the three taxa of Ornithoptera butterflies possesses unique quantitative size values on tapered ridges and irregular multilayers with granular objects and air cavities to express unique structural color. These species‐ or subspecies‐dependent structural colors might have evolved via quantitative shifts in these microarchitectural traits rather than via changes in the basic developmental or architectural plan for color expression.     

Ridge crest versus swale: contrasting plant–water relations and performance indexes in two understory plant species in a coastal maritime forest

Coastal-ridge plains are progradational landforms composed of elevated ridges and low-lying swales. The transitions between ridges and swales are steep, promoting dynamic shifts between xeric and mesic systems. Two understory plants that co-occur in ridge plains of North American mid-Atlantic maritime forests are Sabal minor and Ilex vomitoria. As coastal-ridge plains foster varying amounts of surface and sub-surface water driven largely by topography, the purpose of this study was to evaluate plant–water relations and chlorophyll a fluorescence in these two species. Ridge plants had lower leaf- and xylem-water potentials, lower osmotic potential (I. vomitoria), and lower symplastic water content (S. minor). Although there were no differences in potential- and effective-quantum yields, there were decreases in fluorescence performance index for ridge I. vomitoria and swale S. minor. While the data support potential water-stress conditions in ridge plants of both species, the data also suggest that I. vomitoria and S. minor use different physiological processes to tolerate hydrologically dynamic ridge–swale maritime forests.     

A comparison of cuticular ridge patterns and other morphological characters of Mazamastrongylus odocoilei and Mazamastrongylus pursglovei (Nematoda: Trichostrongyloidea) from white-tailed deer Odocoileus virginianus

The synlophes of Mazamastrongylus odocoilei (Dikmans, 1931) and M. pursglovei (Davidson & Prestwood, 1979) from Odocoileus virginianus were described to provide characteristics for their differentiation from related species in domestic and wild ruminants. The synlophes of M. odocoilei and M. pursglovei were identical. Both had single continuous dorsal, ventral and lateral ridges. Other ridges in the lateral fields in the anterior third of the body angled posteriorly ending adjacent to the single lateral ridge. The ridge system in Mazamastrongylus spp. appears to be unique in lacking the continuous subventral and subdorsal ridges present in all previously studied medium stomach worms from domestic ruminants. Only two characters, spicule length and structure, are known to be useful for differentiating males of M. odocoilei and M. pursglovei, and females cannot be differentiated. Evidence that M. odocoilei and M. pursglovei are separate species include: (1) the two species are frequently found together in the same individual host, but each is also found in the absence of the other; (2) no overlap in spicule size or intergrades in shape have been found although numerous populations have been sampled; and (3) the two species have overlapping, but different, geographical ranges in eastern North America. No differences in the synlophe were found between these two species. The importance of this finding is that the absence of differences in the synlophe is not an unequivocal indicator that nematodes are conspecific.     

Validity Analysis of the Morphological Identification of Three Highly Morphologically Similar Species Belonging to the Genus Niviventer (Rodentia: Muridae)

Cryptic species are prevalent among mammals, and identifying morphological methods or measurements that can effectively distinguish cryptic species has high significance in taxonomy. Three of the white-bellied rats, Niviventer confucianus, N. fulvescens and N. huang (Rodentia: Muridae), have such similar morphological characteristics that taxonomists have not been able to effectively identify them according to their morphologies. Recent studies have determined that the N. fulvescens species complex contains multiple species, indicating that previous morphological comparisons were potentially based on inaccurate species identifications, leading to false conclusions. To clarify whether the morphological differences among these three species can be used for identification, a variety of morphological methods and measurements were combined with molecular species identification to ensure accurate identifications prior to comparing morphological characteristics. The results showed that: (1) only N. confucianus has a white tail tip, distinguishing this species from the other two species but not N. fulvescens from N. huang; and (2) the tail length of N. fulvescens and ear length of N. confucianus are greater than those of the other species. Traditional morphological methods cannot differentiate these species well, with the discrimination rate reaching more than 90%; therefore, they can only be used as auxiliary methods for morphological identification. Additionally: (3) the geometric morphological results of the four skull views can be combined to distinguish the three species, among which the discrimination rate of lateral view of mandible reaches 98%, making it effective for differentiating these species; and (4) the phallic morphologies of the three species differed significantly in the presence of a dorsal groove, thickness of the distal baculum, and the positional relationship between the distal and proximal baccula; thus, this approach can completely distinguish these species. This study examines the applicability of various morphological measurements for the identification of highly morphologically similar species, provides a reference for distinguishing cryptic species produced by convergent evolution or incomplete differentiation by morphology, and suggests that phallic morphology should be the primary characteristic for differentiating such species in the future.

     

A comparison of wheat bulb fly (Delia coarctata) egg numbers in ridge and furrow soil samples from potato crops

In soil samples taken with a shovel from 97 potato maincrops in east Scotland during 1978 to 1981, wheat bulb fly (Delia coarctata) eggs were more numerous on ridges than in furrows. The ratio of the number of eggs on the ridge to the number of eggs in the furrow was higher in Lothian Region (3·25) than in Fife Region (1·59) but differed significantly (P < 0·05) from 1·0 in both Regions. To obtain maximum precision of the estimate of the total wheat bulb fly egg population in a potato field, more samples should be taken from the ridge than from the furrow, in approximate proportion to the egg numbers.     

Taxonomic Study of Korean <Emphasis Type="Italic">Scirpus</Emphasis> L. s.l. (Cyperaceae) II: Pattern of Phenotypic Evolution Inferred from Molecular Phylogeny

Scirpus L. s.l. is well known as one of the polyphyletic groups in Cyperaceae. Recent molecular phylogenetic studies clearly suggested that Scirpus s.l. should be separated into several independent genera. In this study, we intend to present the morphological variations and patterns of phenotypic evolution based on molecular phylogeny of Korean Scirpus s.l. Five genera, including 21 taxa from Korean Scirpus s.l., were examined: three species of Bolboschoenus, three species of Schoenoplectus, eight species of Schoenoplectiella including one hybrid, five species of Scirpus, and two species of Trichophorum. For morphological analyses, 23 and 48 characters were selected from vegetative and reproductive organs, respectively. Molecular phylogeny was inferred from a nuclear ribosomal internal transcribed spacer, the chloroplast rbcL gene, and the chloroplast trnL-F region. Distinct characteristics and quantitative variation was presented for identification of the five genera and their species. A pronounced pattern of morphological character change was reduction, although many other character states seem to be homoplastic. We suggest that the reduction of phenotypic characteristics has been expressed in terms of condensation of internodes, reduction of leaf blade, and simplification of inflorescence among five genera of Korean Scirpus s.l.     

Rides septales à organisation de type tétracoralliaire chez Trachypsammia (Tabulata, Permien)

Précédemment décrite chez Kerforneidictyum et Palaeacis I'organisation des rides septales suivant un schema de type tetracoralliaire est reconnue chez Trachypsammia monoseptata (Permien de Timor) où n'avait été signalé qu'un fort “Medianseptum”. II détermine un plan de symétrie bilatérale dans le calice; la ride cardinale forte est en position dorsale ou interne, la ride antipode également bien développée en position ventrale ou externe souvent plus courte, les rides considérées comme alaires sont identifiables au moins dam leur partie proximale. L'ensemble des rides clairement observables sont les rides majeures (protorides et métarides), les rides mineures sont à peine ébauchées. T. monoseptata pourrait représenter un stade calicinal jeune de T. dendroides. Trachypsammia dendroides (Permien de Timor) posséde un plan de symétrie bilatérale net. la ride cardinale est plus forte et plus longue que les autres rides, la ride antipode plus courte, les rides alaires sont identifiables en coupe transversale. rides majeures el mineures sont bien differenciées; le nombre total de rides est souvent de 32. Chez T. xizangensis (Permien du Tibet), seule une symétrie bilatérale a été observée en coupe. Pas de donnees pour T. mrditerranea (Permien de Sicile). Les affinités systéinatiques très étroites mises en évidence entre Polaeacis et Trachypsammia par les caractéres microstructuraux sont confirmées par Ie dispositif septal, ces Tabulés constituent-ils un groupe particulier? La question est posée A rugosan pattern of the septal ridges, formerly described in Kerforneidictyum and Palaeacis is pointed out in Trachypsammia monoseptata (Permian of Timor) for which only the ‘Medianseptum’ had been observed. T. monoseptata exhibits a strong cardinal ridge in dorsal or internal position. just opposite a shorter counter ridge, thus creating a plane of bilateral symmetry. The ridges assumed to be alar can be identified by their proximal ends being in contact with the ‘Medianseptum’. The major ridges (proto and metaridges) are obvious, the minor ones show only their very proximal ends. T. monoseptuta could be a calicinal young stage of T. dendroides. T. dendroides (Permian of Timor) shows a plane of bilateral symmetry, the cardinal ridge is stronger and longer than the others, the counter shorter, the alar ridges can be identified in transverse section. major and minor ridges are well developed; the number of ridges is often 32. In T.xizangensis (Permian of Tibet) only the bilateral symmetry is known, while there are no data for T mediterranea (Permian of Sicily). The systematic affinities between Palaeacis and Trachiypsammia pointed out on the basis of microstructural data are also supported by the septal ridges pattern. Do Palaeacis, Trochypsammia and others form a special division of Tabulate corals? That is the question     

Genetics of epidermal ridge minutiae

Epidermal ridge minutiae have been utilized widely in Forensic Sciences for personal identification for a long time; but genetical significance of minutiae is yet to be understood thoroughly. In the present communication an attempt has been made to study the genetical aspects of finger ridge minutiae on the basis of family material. Data for the present study were collected from 76 families belonging to the Namasudras, a Scheduled Caste residing in Nadia district, West Bengal, India. An eight-fold classification of minutiae was followed in the present study. Out of eight minutiae types ridge end and connecting ridge have shown the maximum and minimum occurrences, respectively. Bilateral difference in minutia types was not evident but the sex difference was found to be significant. The genetics of minutia types was studied by familial correlation (r) and heritability (h ²) estimates. Statistically significant familial correlation values and high heritability estimates for some of the minutia types such as fork, ridge end and total minutiae are suggestive of hereditary control of minutiae. The results of the present study suggest that minutiae showing significant correlation values and high heritability estimates (more than 60%) are useful in genetical studies and perhaps diagnosis of some genetical disorders in addition to their regular application in personal identification.     

Experimental manipulation leading to induction of dorsal ectodermal ridges on normal limb buds results in a phenocopy of the eudiplopodia chick mutant

Elongation of chick limb buds depends on the presence of the apical ectodermal ridge which is induced by subjacent limb bud mesoderm. Recombination experiments have shown that the limb bud mesoderm loses the capacity to induce ridges by late stage 17. Moreover, in normal limb development only one ridge forms. However, in the eudiplopodia chick mutant accessory ectodermal ridges form on the dorsal surface of limb buds as late as stage 22. Tissue recombinant experiments show that the mutation affects the ectoderm, extending the time it responds to ridge induction (Fraser and Abbott, 1971a, Fraser and Abbott, 1971b while the mesoderm is normal. The result is polydactyly, with extra digits dorsal to the normal digits. Because eudiplopodia limb bud dorsal mesoderm can induce ridges at stage 22 but is unaffected by the gene, genetically normal dorsal limb bud mesoderm may also be able to induce ridges after stage 17. To test this possibility we grafted stages 14–18 flank ectoderm to normal limb bud dorsal mesoderm and found that mesoderm from stages 17 through 20 was able to induce a ridge and subsequently dorsal digits developed. Limbs with duplicate digits were similar to eudiplopodia limbs. In other experiments, stage 18, 19, and 20 leg bud dorsal ectoderm did not form ridges when grafted to leg bud dorsal mesoderm of the same stage, indicating a lack of response to the mesoderm. Finally, the inductive capacity of limb bud mesoderm appeared to be reduced compared to mesoderm at pre-limb bud stages. These experiments demonstrate a spatially generalized potential in limb bud dorsal mesoderm to induce ridges during the stages when the apical ridge is induced. The determination of where the ridge will form and the acquired inability of limb bud dorsal ectoderm to respond to induction by underlying mesoderm are necessary early pattern forming events which assure that a single proximodistal limb axis will form.     

Heterochrony in Shell Sculpture Development within the Ostracode Genus Hemicythere

The evolutionary issues of taxonomic significance of the shell sculpture in Ostracoda are addressed. This is a comparative ontogenetic study of three types of lateral sculpture (fossa-mural reticulation, punctation, and foveolation), as well as flanges, ridges, and tubercles is made in different age stages and morphological variations of three ostracode species with different strengths of the expression of sculpture: Hemicythere borealis (Brady, 1868), H. villosa (Sars, 1866), and H. nana (Schornikov, 1974). It is shown that the development of each sculpture type proceeds relatively independently and represents a mosaic; developmental stages are accompanied by numerous heterochronies. This results in many parallelisms, and even the trend of the evolution of a structure can change. The pathways of morphological evolution of Hemicythere species are discussed.     

Multiplex PCR assay for identifying five species of chigger mites in the Republic of Korea

Chigger mites (Trombiculidae), which are known vectors of Orientia tsutsugamushi, have significantly fewer molecular data available than other known species, with a focus on morphological species identification rather than molecular species identification. However, chigger mites are easily damaged because of small size. In addition, natural variation and adult similarity would interrupt accurate classification and identification. Therefore, in this study, a multiple polymerase chain reaction (PCR) method using the internal transcribed spacer (ITS) region of five frequently occurring species (Euschoengastia koreaensis, Leptotrombidium orientale, Leptotrombidium pallidum, Leptotrombidium palpale, and Leptotrombidium scutellare) among eight species known to mediate the spread of is presented. This is the first report using molecular species identification for the classification method of chigger mites, which was only possible with morphological species identification, and is expected to be used as basic data for vector surveillance.     

Meeting the Deadline: Canada's Arctic Submission to the Commission on the Limits of the Continental Shelf

Abstract

Seafloor highs can be grouped into three legal categories: (i) oceanic ridges; (ii) submarine ridges; and (iii) submarine elevations. The Commission on the Limits of the Continental Shelf recognizes that the foot of slope serves as the qualifier to distinguish oceanic ridges from the two other categories. The Commission established a view that the sole qualifier for a submarine ridge is its morphological continuity with the continental margin. A submarine elevation needs also to share geological characteristics with the rest of the continental margin. Recent recommendations suggest that the Commission may have complicated its view in this respect.     

Lindernia kinmenensis sp. nov. (Scrophulariaceae) from Kinmen (Taiwan)

Lindernia kinmenensis Y. S. Liang, C. H. Chen, & C. L. Tasi sp. nov. from Kinmen (Taiwan) is described. The new species belongs to section Torenioides and is most similar to L. crustacea. It differs from the latter by the following characters: calyx pubescent between the ridges (vs pubescent on ridges), with (2)3(4) bristles on the ridge near the apex of the calyx‐lobes (vs without such bristles), corolla shorter, 6–8 mm long (vs 7–11 mm long) and pale purple (vs purple or blue), posterior theca with obtuse (vs acute) apex. This species is usually found in sandy wetlands. A line drawing, colour photos and SEM micrographs of pollen and seed as aids for identification are provided.     

Morphologie und Funktion der tergalen Längsrippen bei Landisopoden (Oniscoidea,Isopoda, Crustacea)

Zusammenfassung Tergale Längsrippen auf dem Peräon finden sich in folgenden Isopoden-Familien: Trichoniscidae, Buddelundiellidae, Stenoniscidae, Tendosphaeridae, Oniscidae, Platyarthridae, Pentheidae (= Armadillidae). Es wird angenommen, daß sich diese Rippen durch ähnliche ökologische Bedingungen konvergent in den genannten Familien entwickelt haben.Alle behandelten Gruppen zeigen ein ähnliches Rippenmuster. Pro Tergit können 6–12 Rippen vorkommen.Drei Rippentypen können unterschieden werden: 1. derCretoniscellus aegaeus-Typ mit abgerundeten Längserhebungen ohne zusätzliche Strukturen; 2. derHaplo-phthalmus-montivagus-Typ mit einer Reihe von spitzen Höckern entlang dem Rippengrat; 3. derPlatyarthrus-schoebli-Typ mit einer Reihe von der Rippe aufgesetzten großen Schuppenborsten.Ontogenetische Beobachtungen anHaplophthalmus zeigen, daß frischgeschlüpfte Jungtiere die gleiche absolute Rippenhöhe und dieselbe Anzahl der Rippen pro Tergit besitzen wie adulte Tiere.Es wird angenommen, daß die Funktion der Rippen darin besteht, bei Kontakt der tergalen Überfläche mit feuchtem Substrat die dabei auftretenden Adhäsionskräfte zu verringern. Die Rippen müssen demnach (im Zusammenhang mit anderen strukturellen Differenzierungen) als eine wichtige morphologische Anpassung an ein bestimmtes Habitat betrachtet werden. Dieses Habitat ist in der Regel der untere Teil der Humusschicht, der durch enge Zwischenräume und durch permanent gesättigte Luftfeuchtigkeit ausgezeichnet ist.In einem Anhang werden die tergalen Strukturen innerhalb der GattungPlatyarthrus und ihre ökologischen Zusammenhänge analysiert.

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Morphology and function of the tergal ridges in terrestrial Isopods (Oniscoidea, Isopoda, Crustacea)

Summary Longitudinal tergal peraeon-ridges are found in the following isopod families: Trichoniscidae, Buddelundiellidae, Stenoniscidae, Tendosphaeridae, Oniscidae, Platyarthridae, Pentheidae (= Armadillidae). It is presumed that these ridges evolved convergently in the families cited above under similar ecological conditions.The ridge-pattern is similar in all treated groups. There are 6–12 ridges on each peraeon-tergite.Three types of ridges can be differenciated: 1) theCretoniscellus-aegaeus-type showing rounded ridges without accessory structures; 2) theHaplophthalmusmontivagus- type with a row of pointed spikes on top of the ridge; 3) thePlatyarthrus-schoebli- type with a row of big scale-spines situated on the ridge.Ontogenetic observations inHaplophthalmus show that the absolute hight of the ridge and the number of ridges per tergite are the same in newly hatched juveniles as in adults.The function of the ridges is supposed to be a means to reduce the adhesive forces in case the tergal surface comes into contact with wet substrate. The ridges are to be considered an important adaptation (seen in connection with other structural differenciations) for a special habitat which is the under-storey of the litter stratum. This habitat is characterized by very small interstices, and by a permanently saturated moisture.An appendix is dedicated to a tentative analysis of the tergal structures in the genusPlatyarthrus seen in an ecological context.