Unusual basement layer in the midgut of gammaridean Niphargus virei Chevreux (Crustacea,Amphipoda)

Summary The basement membrane of the midgut and posterior caeca epithelium in the gammaridean amphipod Niphargus virei Chevreux, 1896 is made of an unusual structure. This basal lamina, properly called basal layer, shows a dense sheet formed by a system of dense hexagonal plates connected by thin filaments. Histochemical studies and enzymatic reactions lead to the conclusion that these structures are proteinaceous, without collagenous protein, and embedded in a neutral polysaccharide matrix. The possible mechanical significance of these mesenteric structures is discussed.     

The giant cryptic amphipod species of the subterranean genus Niphargus (Crustacea,Amphipoda)

Amphipods from the genus Niphargus represent an important part of the Western Palearctic subterranean fauna. The genus is morphologically diverse, comprising several distinct ecomorphs bound to microhabitats in the subterranean environment. The most impressive among them are “lake giants,” a series of massive, large‐bodied species. These range from morphologically distinct to morphologically cryptic taxa. We analysed the taxonomic structure of the Niphargus arbiter–Niphargus salonitanus species complex, belonging to “lake giants” from the Dinaric Karst (West Balkans), and assessed their phylogenetic, morphological and ecological diversity. Multilocus phylogeny suggested that the complex is monophyletic and nested within other cave lake ecomorphs. Unilocus and multilocus coalescence species delimitations indicated that the complex totals nine species. These species substantially overlap in morphology and cannot be unambiguously told apart without the use of molecular markers. An analysis of splitting events within a palaeogeological context, and modelling of environmental characteristics on the phylogeny unveiled a complex history of diversification. Part of this diversification might have been influenced by ecological divergence along the altitudinal gradient reaching from the Adriatic coast to inland Dinaric mountain chains and Poljes. Other splits coincide with the marine regression–transgression cycles during Pliocene. We describe Niphargus alpheus sp. n., Niphargus anchialinus sp. n., Niphargus antipodes sp. n., Niphargus arethusa sp. n., Niphargus doli sp. n., Niphargus fjakae sp. n. and Niphargus pincinovae sp. n., and by doing so hope to prompt their further research.     

Observations on the feeding behaviour of the Antarctic Gammarid Eusirus perdentatus Chevreux, 1912 (Crustacea: Amphipoda) in aquaria

Summary The feeding behaviour of adult Eusirus perdentatus was observed in aquaria. These observations and the analysis of gut contents of preserved specimens demonstrate that this species is a carnivorous predator feeding on polychaetes, amphipods and other small crustaceans. Apparently the localization and capture of prey in aquaria follows a fixed pattern.     

A phylogenetic perspective on 160 years of troubled taxonomy of Niphargus (Crustacea: Amphipoda)

Niphargus is the largest genus of freshwater amphipods. Its systematics from the species to the family level has always been problematic. This study is the first comprehensive phylogenetic treatment of the chiefly subterranean group in 160 years of its taxonomic history. It includes 103 niphargid species plus outgroups, representing about one‐third of all nominal species. The samples originated mainly from type localities or adjacent sites and covered most of the morphological variability of the genus. Character sampling included nuclear 28S and mitochondrial 12S rDNA sequences, and 122 morphological characters. Quantitative morphological traits were coded using two alternative methods. The first one searches for gaps in the variability range of each character, while the second one uses absolute differences between the standardized raw data as weights. Different data sets yielded alternative topologies. All data support the monophyly of Niphargidae, while Niphargopsis— another niphargid genus — was consistently nested within Niphargus, loosing justification for its separate status. We predict a similar fate for all or most of the remaining six small niphargid genera, which were not yet scrutinized phylogenetically. Different topologies agreed in species composition of five large, well‐supported clades, although the hierarchic relationships between them remain unresolved. These clades reject all previously proposed taxonomic subdivisions of Niphargus, implying a high degree of morphological homoplasy that renders any morphology‐based groups questionable. The clade members are distributed within well‐established zoogeographical regions that do not exceed 1300 km across the longest diagonal. These results provide a framework for future studies on niphargid systematics, the evolution of endemism and cryptic diversity in subterranean environments, the mechanisms leading to exceptional morphological heterogeneity, historical biogeography, and applied ecological issues.     

Molecular phylogeny of the subterranean genus Niphargus (Crustacea: Amphipoda) in the Middle East: a comparison with European Niphargids

The subterranean genus Niphargus is one of the most species‐rich genera among freshwater amphipods in the world, distributed in the Western Palearctic. Thus far, taxonomic and phylogenetic research has focused mainly on the European half of the genus range. In this study, 25 populations of Niphargus from Iran, Lebanon and the Crimean Peninsula were investigated. Bayesian inference based on 28S, H3 and COI gene sequences suggests that populations from the area belong to four different clades. Three species from Crimea and one species from Iran are nested at basal nodes, indicating their rather ancient origin. The rest of the species are younger and belong to two separate clades. One Crimean species is a sister‐species to east Romanian species. The second clade includes one species from Lebanon and all but one population from Iran. The origin of this clade corresponds to marine transgression between the Black Sea and Mediterranean approximately 12 Mya. This clade was further investigated taxonomically. Revision of qualitative morphological traits and unilocus species delimitation methods using COI suggest that this clade comprises 12–16 species, of which only three have been described so far. Multilocus coalescence delimitation methods (using fragments of COI, 28S, H3 and ITS) strongly supported 11 of these species. The remaining populations comprise at least two species complexes that require further and more detailed taxonomic research. © 2015 The Linnean Society of London     

Strahlenbiologische Untersuchungen an Gammariden (Crustacea,Amphipoda)

Zusammenfassung 1. Der Einfluß einmaliger Röntgenbestrahlungen auf die Überlebenszeiten der euryhalinen AmphipodenGammarus duebeni Lilljeborg,Gammarus salinus Spooner undGammarus zaddachi Sexton wurde bei einer konstanten Temperatur von 15⁰ C und einem Salzgehalt von 10 untersucht.2. Bestrahlungen mit Dosen von 625 und 1250 R führen beiG. duebeni zum vorzeitigen Tod von nur einigen Versuchstieren, Bestrahlungen mit 2500 R und höheren Dosen zum vorzeitigen Tod aller Versuchstiere.3. BeiG. duebeni sind die strahlenempfindlicher als die , die Jungtiere strahlenempfindlicher als adulte Individuen.4.G. salinus undG. zaddachi sind strahlenempfindlicher alsG. duebeni.5. Die LD₅₀-Kurven lassen drei Bereiche erkennen. Bei mittleren Dosen ändert sich die Zeitspanne, in der 50% der Versuchstiere sterben, nur wenig oder gar nicht mit der Dosis. Bei hohen und niedrigen Dosen ist die Überlebenszeit dosisabhängig.6. Die Strahlenempfindlichkeit vonG. duebeni war im ersten Quartal des Jahres 1967, in dem die Temperaturen über den langfristigen Monatsmitteln lagen, geringer als bei Flohkrebsen, die zu einem späteren Zeitpunkt gefangen wurden oder aus Laboratoriumszuchten stammten.7. Die Häutungsvorgänge, deren Beeinflussung nur beiG. duebeni untersucht wurde, werden durch Bestrahlungen mit 1250 R oder geringeren Dosen nicht beeinflußt.8. Nach einer Bestrahlung mit 20 000 R sind 2 Tage nach der Bestrahlung nur wenige oder gar keine Häutungen möglich. Nach Bestrahlungen mit 10 000 und 5000 R erfolgen die Häutungen verspätet.9. Als Folge von Bestrahlungen mit letalen Dosen nimmt die Zahl der Häutungen um den 30. Tag nach der Bestrahlung ab.10. Die Häutungsvorgänge waren bei Tieren, die im ersten Quartal 1967 gefangen und bestrahlt wurden, weniger beeinflußbar als bei Tieren, die aus Laboratoriumszuchten stammten oder zu einem späteren Zeitpunkt gefangen wurden.11. Nach Bestrahlungen mit letalen Dosen treten zwei kritische Phasen auf. Ein Teil der mit mittleren und der größte Teil der mit hohen Dosen bestrahlten Tiere stirbt bereits in der ersten kritischen Phase. Die zweite kritische Phase wird von allen mit niedrigen Dosen bestrahlten Tieren erreicht. Tiere, die sich in der ersten kritischen Phase häuten, haben eine geringe Lebenserwartung.12. Die Überlebenszeit des einzelnen Individuums hängt außer von der Bestrahlungsdosis von dem Zeitpunkt ab, zu dem es sich innerhalb der Versuchszeit häutet.

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Radiobiological investigations on gammarids (Crustacea, Amphipoda)

Effects of single exposures of X-radiation on survival were studied inGammarus duebeni, G. salinus andG. zaddachi under constant conditions of temperature (15⁰ C) and salinity (10 ). Effects on moulting were investigated inG. duebeni. The amphipods were irradiated with doses between 625 and 20,000 R.G. salinus andG. zaddachi are equally radioresistant (LD_50/30 : 1,700 R) but less resistant thanG. duebeni (LD_50/30(males) : 3,900 R; LD_{50/30(females)} : 3,500 R). At high doses, half of the test individuals die within a few days; at medium doses survival time is dose-independent; at lower doses survival time again increases with decreasing doses up to dose-ranges (below 1,250 R forG. duebeni, 1,000 R forG. salinus andG. zaddachi), at which only a few individuals die before their natural death. Subadult gammarids are less resistant;G. duebeni of 4 to 7 mm body length have a LD_50/30 of 2,200 R. Death distribution after medium doses indicates that at least two mechanisms are involved in acute mortality. A first mortality maximum occurs shortly after irradiation; subsequently, mortality decreases for a few days, and is followed by another maximum. At lower doses no individual dies during the first critical period. Shortening of survival time at higher doses results from survival of fewer individuals to the second critical period. Few or no moults occur inG. duebeni irradiated with 20,000 R following the second day after irradiation and after the 30th day in those individuals irradiated with 2,500 to 10,000 R; moulting is delayed after exposure to 5,000 to 10,000 R. Individuals ofG. duebeni taken from the field during the mild winter 1966/67 were more resistant to radiation, and moulting was less affected, than in laboratory-reared amphipods, or in those collected in the field during other seasons. Besides on irradiation dose, survival time of an individual depends on the time of its moulting in the course of an experiment.

     

Australian Iphimediidae (Crustacea: Amphipoda)

Australian species of the iphimediid amphipod genus Iphimedia are revised. Based on new material from inshore and continental shelf habitats six new species are described: Iphimedia beesleyae; I. filmersankeyi; I. kateae; I. lisae; I. neuweileri and I. oetkeri. Four established species are redescribed: I. ambigua Haswell, 1879; I. discreta Stebbing, 1910; I. edgari (Moore, 1981) and I. warraina (Thomas and Barnard, 1991). A key to Australian species of Iphimedia is provided. Full article published online at http://www.senckenberg.de/odes/06-09.htm     

Digestive anatomy of Halella azteca (Crustacea,Amphipoda)

The digestive tract of the freshwater amphipod Hyalella azteca is a straight but differentiated tube consisting of foregut, midgut, and hindgut divisions. The foregut is subdivided into a tubular esophagus, a cardiac stomach, and a pyloric stomach. The cuticular lining of the cardiac stomach is elaborated into a set of food-crushing plates and ossicles, the gastric mill, while the pyloric cuticle forms a complex straining and pressing mechanism. Nine caeca arise from the midgut, seven anteriorly and two posteriorly. Four of the anterior caeca, the hepatopancreatic caeca, are believed to be the primary sites of digestion and absorption. The remaining caeca may be absorptive, secretory, or both. The much-folded hindgut wall is capable of great distention by extrinsic muscle action for water intake to aid in flushing fecal material out of the anus; such action also may stimulate antiperistalsis by intrinsic rectal muscles.     

The imprint of Quaternary glaciers on the present-day distribution of the obligate groundwater amphipod Niphargus virei (Niphargidae)

Aim A plausible yet untested biogeographical scenario suggests that Quaternary glaciers shaped the present‐day distribution of the groundwater amphipod Niphargus virei. This study was designed to test two hypotheses pertaining to this scenario: (1) the probability of occurrence of N. virei in ice‐free areas decreases in the vicinity of the Würm glacier; and (2) dispersal is sufficiently low for the historical record of glacial effects to persist over time. Location The study area was located in the southern Jura Mountains, France. Methods A total of 497 sites were sampled to ascertain the distribution of N. virei in the southern Jura. Amplified fragment length polymorphism was analysed from a subset of 24 sites. The relationships between the probability of occurrence of N. virei and distance to the Würm glacier or elevation were investigated using a logistic regression. Spatial autocorrelation analyses were performed on both the residuals of the logistic regression and genetic distance to test the significance of dispersal and barriers to post‐glacial recolonization. The influence of catchment boundaries as barriers to dispersal was examined using different neighbouring relationships between sites. We tested the statistical significance of the reduction in deviance and gain in precision of an autologistic regression that took into consideration the influence of dispersal constraints on the distribution of N. virei. Results Niphargus virei rarely occurred in formerly glaciated areas, and its probability of occurrence in ice‐free areas decreased in the vicinity of the Würm glacier. Combined autocorrelation analyses of spatial distribution and spatial genetic structure showed that: (1) the distance at which spatial autocorrelation was no longer significantly positive did not exceed 16 km; (2) genetic differentiation fitted a model of isolation by distance; and (3) catchment boundaries acted as barriers to dispersal. The autologistic regression with dispersal constraints significantly increased our capacity to predict the distribution of N. virei. Maps of probabilities of occurrence suggested that post‐glacial recolonization was impeded by the extension of glacial outwash. Main conclusions The present distribution of N. virei in southern Jura is probably the result of a historical range reduction driven by glaciation coupled with restricted dispersal and isolation by distance.     

Comparative analysis of the circulatory system in Amphipoda (Malacostraca, Crustacea)

We present data on the haemolymph vascular system (HVS) in four representatives of the major amphipod lineages Gammaridea, Hyperiidea and Caprellidea based on corrosion casting and three‐dimensional reconstructions of histological semi‐thin sections. In all these species the HVS comprises a dorsal pulsatile heart, which is continued in the body axis by the anterior and posterior aortae. The heart is equipped with three pairs of incurrent ostia. The number of cardiac arteries that lead off the heart varies among species: in the studied Gammaridea four pairs occur, in Hyperia galba only the three posterior pairs of cardiac arteries occur, while in Caprella mutica cardiac arteries are absent. In all the studied species the posterior aorta leads as a simple tube into the pleon attached to the dorsal diaphragm. The anterior aorta runs from its origin in the anterior part of the second thoracic segment into the cephalothorax. Both pairs of antennae have an arterial supply off the anterior aorta. An overview of previously studied species including our present findings shows the amphipod HVS to be relatively uniform and the gammarid form is discussed as being closest to the ground pattern of Amphipoda.     

Caprellids (Crustacea: Amphipoda) from India

The caprellid fauna of India is investigated. A total of 538 samples (including algae, seagrasses, sponges, hydroids, ascidians, bryozoans, encrusted dead corals, coral rubble, fine and coarse sediments) were collected from 39 stations along the coast of India, covering a wide diversity of habitats from intertidal to 12 m water depth. A new species (Jigurru longimanus n.sp.) is described, and figures of the 11 valid species reported so far from India are given together with a key for their identification. No caprellids were found in sediments from the northeast (16–20oN) coast of India while they were abundant in the southeast and west coast. Decreases in salinity due to river discharges associated with lower values of oxygen, higher water temperatures and lower nutrient inputs along the east coast could explain these differences in caprellid composition between the two coastlines. Significantly, lower abundance of caprellids in India, as in other tropical ecosystems, is probably related to the lack of species belonging to the genus Caprella, which reach very high abundances in temperate waters.     

Karyotypes of the Echinogammarus berilloni-group (Crustacea,Amphipoda) from Spain

The chromosome number and karyological features of Iberian populations of seven species of the Echinogammarus berilloni-group (Crustacea, Amphipoda) have been studied. For comparison, Gammarus gauthieri, belonging to the G. pulex-group was also studied. Four species of the berilloni-group share the same number n=27. Other numbers found were n=25, n=26 and n=28. The chromosomes of these species have a centromeric region surrounded by large heterochromatic blocks at late prophase. There-after, the centromere splits precociously. C. gauthieri has n=26, the same number found in the pulex-group. This species has larger chromosomes than the former but it does not show these karyological peculiarities.Cytological observations confirm both the close relationship among species of the berilloni-group and the differentiation with respect to the pulex-group. On the other hand, the existence of different numbers confirms other results that reject the older idea that speciation within Gammaridea occurred with minor changes in karyotypic characters.     

New hyalellids (Crustacea, Amphipoda, Hyalellidae) from Lake Titicaca

Two new species of hyalellid amphipods, Hyalella crawfordi and H. gauthieri, are described from Lake Titicaca; H. echinus (Faxon, 1876) is redescribed. The H. echinus group of species is newly proposed for these three species, and a group diagnosis is provided. A key to the three species in the group is provided Full article published online at http://www.senckenberg.de/odes/06-10.htm.     

Taxonomy and biogeography of <Emphasis Type="Italic">Niphargus steueri</Emphasis> (Crustacea: Amphipoda)

Niphargus steueri (Niphargidae) comprises a complex of four subspecies (N. s. steueri, N. s. kolombatovici, N. s. subtypicus, and N. s. liburnicus), the morphology and distribution of which have been poorly known until now. New diagnostic characters of the species and its four subspecies are presented and illustrated. The species is distributed along the major part of the Dinaric Karst, between Slovenia in the northwest and Bosnia and Herzegovina in the southeast. The distribution of the four subspecies approximately resembles the distribution of the evolutionary lineages of the subterranean amphibian Proteus anguinus and the Dinaric lineage of the cave shrimp Troglocaris agg. anophthalmus. Niphargus s. steueri is restricted to the Istran Peninsula; N. s. subtypicus is distributed in southeast Slovenia and northwest Croatia; N. s. liburnicus is known from two disjunctive localities, one on the island of Krk (Croatia) and the other in Gorizia (Italy); and N. s. kolombatovici is restricted to Dalmacija and Herzegovina. The somewhat variable putative synapomorphies of N. steueri probably suggest that the group is old and that the present distribution pattern is a result of historical events, possibly events in the Miocene Dinaride Lake system. Two populations of N. s. kolombatovici and one population of N. s. subtypicus deviate from the general distributional pattern and may belong to cryptic taxa that cannot be distinguished on the basis of morphology. Both hypotheses corroborate with the estimated times of divergence and with the number of independent lineages in the similarly distributed but unrelated stygobionts Proteus and Troglocaris.     

Life cycle ofCorophium insidiosum (Crustacea,Amphipoda) in laboratory culture

The life cycle ofCorophium insidiosum (Crawford) was investigated for the first time in laboratory cultures. This amphipod is mainly a suspension feeder, but it can also switch to deposit feeding. It was cultivated in standing, unaerated finger bowls, feeding on detritus, living or dried algal matter, rotifers (Brachionus plicatilis), or large-sized phytoplankton (e. g. the flagellateScrippsiella faeroense). A mixture of these items gave best results and hence was used for long-term cultivation. Preliminary results are presented on ingestion rate (suspension feeding), digestion rate, starvation resistance, and elemental and biochemical composition. In the life cycle ofC. insidiosum, several factors were found to play an important role: temperature, individual age, sex, and in contrast to other amphipod species thus far studied also the age of the mother animal at the time of breeding. Increasing temperature reduces the total life span, the age and size at the time of attaining sexual maturity, and the duration of marsupial development. It increases growth and moulting rate. At increasing individual age, the growth rate, and in males also the moulting rate, decrease, while the number of offspring per brood and surprisingly also the duration of its marsupial development increase. Females generally have a longer life span than males, and they show a higher number of moults, higher moulting frequency and growth rate, and a larger maximum body size. Body length and age at the time of reaching sexual maturity are smaller in males than in females. Furthermore the age of the mother animal at the time of breeding proved to be of particular importance: Individuals from early broods have an apparently longer life span than those originating from late broods, and they have more moults, mostly a higher growth rate, higher number of broods, higher total number of offspring, and, surprisingly, also a longer period of incubating their broods. These major factors have differing combined effects.     

Experimental studies on the life cycle ofJassa falcata (Crustacea,Amphipoda)

Jassa falcata (Leach), an unselective suspension feeder, was cultivated in standing, unaerated finger bowls, feeding on a mixture ofBrachionus plicatilis, Scrippsiella faeroense, Ulva spec., and natural detritus. This amphipod can also be maintained with diets composed of dead or live material of both plant and animal origin, but an addition of living zooplankton is necessary for longterm cultivation. Starvation resistance is higher in females than in males, and it is increased by lower temperatures. The life span ofJ. falcata increases with decreasing temperature, and it is generally higher in females (maximum: 252 days at 10°C) than in males. In laboratory culture, a bimodal mortality pattern is typical with high juvenile death rates, low mortality during the reproductive phase, and again increasingly high death rates toward the end of the life cycle. Growth rate depends on temperature, sex, and individual age. The temperature dependence of growth is particularly high in males, and it is higher in adults than in juveniles. The total number of moults is lower in males (5 to 6) than in females (7 to 9). Sexual maturity is attained at moult IV to V. The average incubation time of eggs is about 9 to 16 days (highest value at 10°C). Three to 4 broods were observed, with largest numbers of offspring at 10°C.     

Global diversity of amphipods (Amphipoda; Crustacea) in freshwater

Amphipods are brooding peracaridan crustaceans whose young undergo direct development, with no independent larval dispersal stage. Most species are epibenthic, benthic, or subterranean. There are some 1,870 amphipod species and subspecies recognized from fresh or inland waters worldwide at the end of 2005. This accounts for 20% of the total known amphipod diversity. The actual diversity may still be several-fold. Amphipods are most abundant in cool and temperate environments; they are particularly diversified in subterranean environments and in running waters (fragmented habitats), and in temperate ancient lakes, but are notably rare in the tropics. Of the described freshwater taxa 70% are Palearctic, 13% Nearctic, 7% Neotropical, 6% Australasian and 3% Afrotropical. Approximately 45% of the taxa are subterranean; subterranean diversity is highest in the karst landscapes of Central and Southern Europe (e.g., Niphargidae), North America (Crangonyctidae), and Australia (Paramelitidae). The majority of Palearctic epigean amphipods are in the superfamily Gammaroidea, whereas talitroid amphipods (Hyalella) account for all Neotropic and much of the Nearctic epigean fauna. Major concentrations of endemic species diversity occur in Southern Europe, Lake Baikal, the Ponto-Caspian basin, Southern Australia (including Tasmania), and the south-eastern USA. Endemic family diversity is similarly centered in the Western Palearctic and Lake Baikal. Freshwater amphipods are greatly polyphyletic, continental invasions have taken place repeatedly in different time frames and regions of the world. In the recent decades, human mediated invasions of Ponto-Caspian amphipods have had great impacts on European fluvial ecosystems. Guest editors: E. V. Balian, C. Lévêque, H. Segers and K. Martens Freshwater Animal Diversity Assessment     

The behaviour of Corophium volutator (Crustacea: Amphipoda)

The behaviour of Corophium volutator (Pallas) is outlined. Swimming, crawling, burrowing and feeding activities are described in detail. Animals usually swim on their backs. Every few seconds, swimming alternates with passive sinking. Animals can crawl over surfaces in and out of water. Out of water they do so by a looping motion using their second antennae and telson. When out of water animals crawl away from light and down slopes. In water they swim towards light. Burrowing is initiated by rapid beating of the pleopods; the animal then sinks below the surface by a concerted action of pereiopods, pleopods, telson, uropods and second antennae; within a few minutes, a shallow burrow is formed. The formation of permanent burrows is dependant on particle size, on adhesive properties of detritus and primary films on sand particles, and on a secretion produced by the animal itself. Individuals can turn about in permanent burrows. The species is essentially a detritus feeder. Animals normally feed only when in their burrows, by using their second antennae to scrape material from the substrate surface into the entrance of the burrow. This material is then transported to the mouth by the feeding appendages and respiratory current. The behaviour of small and large animals differs; small animals burrow rapidly and permanently, and do not emerge spontaneously; furthermore, they only swim occasionally. Large animals swim more frequently, spend more time on the substrate surface, and periodically move burrows. It is suggested that new habitats are colonized by large animals which have already bred once.     

On the nutrition of two Antarctic acanthonotozomatidae (Crustacea: Amphipoda)

Summary Two species of Antarctic acanthonotozomatid amphipods (Echiniphimedia hodgsoni and Maxilliphimedia longipes) have been investigated in regard to their food preference. Examinations of food remains in foreguts and midguts indicate that Echiniphimedia hodgsoni feeds on sponges and Maxilliphimedia longipes ingests Cnidaria. These foregut analyses are supported by a study of the functional morphology of the mouthparts. The structure of the mandibles in particular can be interpreted as an adaptation to the presumed food source. The right mandible of Echiniphimedia hodgsoni bears a lacinia mobilis which works as an additional cutting edge. By means of this cutting mechanism Echiniphimedia hodgsoni should be able to bite out tough sponge material. The mandibular endites of Maxilliphimedia longipes are medially excavated, the incisors are regulary toothed and the molars vestigial. Such kinds of mandibles are adapted to cut large fragments of soft food, i.e. the mucous tissue of Cnidaria.