The geographic distribution of the European Branchiopods (Anostraca,Notostraca, Spinicaudata,Laevicaudata)

The Large Branchiopod fauna of Europe consists of 72 species and sub-species: 50 anostracans, 8 notostracans, 12 spinicaudatans, and 2 laevicaudatans. Their geographical distribution is mapped, and remarks on ecological requirements of species are given.     

The ovary structure and oogenesis in the basal crustaceans and hexapods. Possible phylogenetic significance

Recent large-scale phylogenetic analyses of exclusively molecular or combined molecular and morphological characters support a close relationship between Crustacea and Hexapoda. The growing consensus on this phylogenetic link is reflected in uniting both taxa under the name Pancrustacea or Tetraconata. Several recent molecular phylogenies have also indicated that the monophyletic hexapods should be nested within paraphyletic crustaceans. However, it is still contentious exactly which crustacean taxon is the sister group to Hexapoda. Among the favored candidates are Branchiopoda, Malacostraca, Remipedia and Xenocarida (Remipedia + Cephalocarida). In this context, we review morphological and ultrastructural features of the ovary architecture and oogenesis in these crustacean groups in search of traits potentially suitable for phylogenetic considerations. We have identified a suite of morphological characters which may prove useful in further comparative studies.     

A phylogenetic analysis of the Conchostraca and Cladocera (Crustacea, Branchiopoda, Diplostraca)

A computer-assisted cladistic analysis on morphological characters of the Diplostraca (Conchostraca and Cladocera) has been undertaken for the first time. The morphological information has been obtained from literature and transformed into 56 suitable characters. The analysis included 47 ingroup taxa, comprising five conchostracan taxa (four families of the Spinicaudata and the Laevicaudata) and 42 genera of the Cladocera. A detailed character discussion is presented which will be a useful working base for future phylogenetic studies on the group. A number of systematic groups were, with differing degrees of certainty, supported in all 218 equally short trees. These are the Diplostraca, Cladocera, Gymnomera (Onychopoda and Haplopoda), Onychopoda, Podonidae, Cercopagididae, Anomopoda, Daphniidae, Moininae, Scapholeberinae, Chydoridae, Chydorinae and Sididae. The Spinicaudata were only supported on some of the 218 equally short trees while no support was found for the Conchostraca. Two taxa—the Macrothricidae and Aloninae—were relatively strongly indicated to be paraphyletic. A suggested classificatory hierarchy, without indication of absolute rank, is presented.     

Anostraca,Notostraca, Laevicaudata and Spinicaudata of Pannonian region and in its Austrian area

The northwestern area of the Pannonian Lowland extends into Austria. The climatic and hydrologic attributes of this biographic region promote the existence of extremely astatic bodies water lacking any fish and hence the occurrence of Anostraca, Notostraca, Laevicaudata and Spinicaudata. Zoogeographical and ecological features as well as the extinction of species due to anthropogenic influence are described.Dedicated to Prof. Dr F. Berger, Lunz, Austria, on the occasion of his 90th birthdayDedicated to Prof. Dr F. Berger, Lunz, Austria, on the occasion of his 90th birthday     

The nauplius eye complex in 'conchostracans'(Crustacea, Branchiopoda: Laevicaudata, Spinicaudata, Cyclestherida) and its phylogenetic implications

The nauplius eye in Cyclestherida, Laevicaudata and Spinicaudata (previously collectively termed Conchostraca) consists of four cups of inverse sensory cells separated by a pigment layer and a tapetum layer. There are two lateral and two medial cups, a ventral medial cup and a posterior medial cup. The pigment and tapetum layers contain two different kinds of pigment granules, the inner pigment layer relatively large, dark (and electron dense) granules, and the outer tapetum layer light, reflective pigment granules. The presence of four cups and two different kinds of pigment granules are interpreted as autapomorphies of Phyllopoda. The position and shape of the nauplius eye in Spinicaudata is very distinct and herein interpreted as an autapomorphy of this taxon.Additional frontal eyes might be present dorsally or ventrally in varying proximity to the nauplius eye, but they have separate nerves from their sensory cells to the nauplius eye centre in the protocerebrum. Rhabdomeric structures are present in all these frontal eyes, evidencing their light sensitivity. In Lynceus biformis and L. tatei (Laevicaudata), two pairs of frontal eyes were found. In Cyclestheria hislopi (Cyclestherida), an unpaired ventral frontal eye is present. We did not find additional frontal eyes in Limnadopsis parvispinus and Caenestheriella sp. (Spinicaudata).     

Global diversity of large branchiopods (Crustacea: Branchiopoda) in freshwater

With about 500 known species worldwide, the large brachiopods are a relatively small group of primitive crustaceans. With few exceptions they live in temporary aquatic systems that are most abundant in arid and semi arid areas. As many regions remain unexplored and as especially the number of species in clam shrimps and tadpole shrimps is underestimated due to difficult identification, the species list will increase with future surveys. The Branchiopoda are monophyletic, but inter-ordinal relationships, as well as many evolutionary relationships at lower taxonomic levels are still unclear. Ongoing molecular studies will more accurately depict species diversity and phylogenetic patterns. With the exception of some anostracan families, most families are not restricted to the northern or southern hemisphere or specific zoogeographical regions. Large branchiopods are used for the assessment of the quality and function of temporary wetlands. Due to the reduction in number and quality of temporary wetlands, several species became endangered and are red listed by the IUCN. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The large branchiopods (Anostraca,Notostraca and Spinicaudata) of Numidia (Algeria)

Between 1995 and 1999, we surveyed the large branchiopods (Crustacea, Branchiopoda) of Numidia, the coastal plain of northeastern Algeria. Samples from ca 100 sites yielded two species of Anostraca (Chirocephalus diaphanus, new to Numidia, and Tanymastix stagnalis), one notostracan (Lepidurus apus lubbocki) and one spinicaudatan (Cyzicus tetracerus). The absence of Streptocephalus torvicornis buchetiis noteworthy. An annotated check-list of all large branchiopods known from Algeria is also presented and discussed. Several species appear to be in danger of extinction.     

Larval development of Lynceus brachyurus (Crustacea, Branchiopoda, Laevicaudata): redescription of unusual crustacean nauplii, with special attention to the molt between last nauplius and first juvenile

The larval development of "conchostracans" has received only scattered attention. Here I present the results of a study on the larval (naupliar) development and the metamorphosis of Lynceus brachyurus, a member of the bivalved branchiopod order the Laevicaudata. Lynceus brachyurus is the only species of the "Conchostraca" in Denmark. The phylogenetic position of the Laevicaudata has traditionally been a source of controversy, and this study does not solve the question completely. This work focuses on features potentially important for phylogeny. The general appearance of the larvae of L. brachyurus has been known for more than a century and a half, and some of its unique features include a large, larval dorsal shield; a huge, plate-like labrum; and a pair of immovable, horn-like antennules. However, many details relating to limb morphology, potentially important for phylogeny, have not been studied previously. Based on size categories, five or six larval stages can be recognized. The larvae approximately double their length and width during development (length: 230-520 microm). Most morphological features stay largely unchanged during development, but the antennal coxal masticatory spines are significant exceptions: they become bifid after one of the first molts. In all larval stages only the antennae and the mandibles actively move. In late naupliar stages the trunk limbs become visible as rows of laterally placed, undeveloped, and still immovable lobes. Swimming is performed by the antennae, whereas the mandibles appear to be involved mainly in feeding, as in other branchiopod larvae. The last naupliar stage undergoes a small metamorphosis to the first juvenile stage, the details of which in part were studied by following the premolt juvenile condition through the cuticle of the last stage nauplius. Among other changes there is a characteristic change in the shape and morphology of the univalved dorsal naupliar shield to a bivalved juvenile carapace. The general morphologies of the antennae and the mandibles are very similar to those of other branchiopod larvae and fall well within the "branchiopod naupliar feeding apparatus" recognized as a branchiopod synapomorphy by Olesen (2003), but some specific features shared with the larvae of other "conchostracans" are also identified. These special "conchostracan" features include: 1) a similar antennular setation; 2) a similar comb-like setulation of the bifid antennal coxal processes; and 3) mandibular palpsetae with setules condensed. In light of recent suggestions concerning branchiopod phylogeny (Cyclestheria as a sister group to the Cladocera), these similarities probably do not support a monophyletic "Conchostraca" but rather are symplesiomorphies of this taxon. A final decision must await a phylogenetic analysis of a more complete set of characters.     

Resting eggs of Anostraca,Notostraca and Spinicaudata (Crustacea,Branchiopoda) occurring in France: identification and taxonomical value

The external egg morphology of the phyllopod species recorded in France is described by means of S.E.M. Differences in diameter and ornamentation of envelope are stressed. We propose a dichotomous key to allow the identification of species even when their biotope is dry. Results are compared with previous studies on Anostraca, Notostraca and Spinicaudata and their taxonomical value is discussed.     

Functional morphology of amplexus (clasping) in spinicaudatan clam shrimps (Crustacea,Branchiopoda) and its evolution in bivalved branchiopods: A video‐based analysis

Male clam shrimps (Crustacea: Branchiopoda: Laevicaudata, Spinicaudata, and Cyclestherida) have their first one or two trunk limb pairs modified as “claspers,” which are used to hold the female during mating and mate guarding. Clasper morphology has traditionally been important for clam shrimp taxonomy and classification, but little is known about how the males actually use the claspers during amplexus (clasping). Homologies of the various clasper parts (“movable finger,” “large palp,” “palm,” “gripping area,” and “small palp”) have long been discussed between the three clam shrimp taxa, and studies have shown that only some structures are homologous while others are convergent (“partial homology”). We studied the clasper functionality in four spinicaudatan species using video recordings and scanning electron microscopy, and compared our results with other clam shrimp groups. General mating behavior and carapace morphology was also studied. Generally, spinicaudatan and laevicaudatan claspers function similarly despite some parts being nonhomologous. We mapped clasper morphology and functionality aspects on a branchiopod phylogeny. We suggest that the claspers of the three groups were adapted from an original, simpler clasper, each for a “stronger” grip on the female's carapace margin: 1) Spinicaudata have two clasper pairs bearing an elongated apical club/gripping area with one setal type; 2); Cyclestherida have one clasper pair with clusters of molariform setae on the gripping area and at the movable finger apex; and 3) Laevicaudata have one clasper pair, but have incorporated an additional limb portion into the clasper palm and bear a diverse set of setae. J. Morphol. 278:523–546, 2017. © 2017 Wiley Periodicals, Inc.     

Survey of large branchiopods on Aruba and observations on taxonomic characters in Leptestheria (Spinicaudata)

A survey of more than 60 ephemeral pools during March 1989 resulted in finding three large branchiopods not previously known to occur on the Caribbean Island of Aruba. These were two Anostraca, Dendrocephalus spartaenovae Margalef, 1967 and Thamnocephalus venezuelensis Belk & Pereira, 1982, and one Spinicaudata, Leptestheria venezuelica Daday, 1923. The notostracan previously reported from Aruba, Triops longicaudatus (LeConte, 1846), was also collected from several pools. All of these species occur also in Venezuela, which is separated from Aruba by an ocean gap of about 25 km. Comparison of Leptestheria venezuelica with Leptestheria compleximanus (Packard, 1877) demonstrated that cephalic morphology provides useful taxonomic features including length of rostrum, depth of occipital notch, shape of the occipital region, and protrusion of the eye capsule. These features may prove useful in studying other species of Leptestheria.     

Larval and post-larval development of the branchiopod clam shrimp Cyclestheria hislopi (Baird, 1859) (Crustacea, Branchiopoda, Conchostraca, Spinicaudata)

The larval and post-larval development of Cyclestheria hislopi is examined by SEM. There are at least nine stages (excluding the adult) – six larval and three post-larval stages. The first four stages are passed within the egg-membrane. The larval and the post-larval phase are separated by a profound change in morphology that takes place between stages VI and VII. The larva shifts from a dorso-ventrally flattened 'larval' appearance up to stage VI to a laterally flattened, more 'adult' appearance from stage VII. New morphological data have been revealed by this study, including (1) a large and globular larval dorsal organ; (2) the carapace starts its development from the segments of the first and second maxillae; (3) the anterior ramus of the second antenna in adult Cyclestheria hislopi is the endopod, and the posterior ramus the exopod. Direct development of the brood in Cyclestheria hislopi – unique among conchostracans – is compared with that of the Cladocera. If Cyclestheria is the sister group to the Cladocera, as favoured in this work, the classical neoteny theory of the Cladocera must be reconsidered, as there is no particular similarity between any adults of the Cladocera and any of the larval stages of Cyclestheria . It is suggested that Cyclestheria displays the type of development present in a cladoceran ancestor. A comparison between Cyclestheria and the Upper Cambrian 'Orsten' fossil Rehbachiella kinnekullensis reveals a remarkable similarity in the endite morphology of the trunk limbs.     

Rediscovery of Leptestheria dahalacensis and Eoleptestheria ticinensis (Crustacea: Branchiopoda: Spinicaudata): an overview on presence and conservation of clam shrimps in Austria

According to recent literature, five of the six known Austrian conchostracan species are extinct. However, interim results of a current study on large freshwater branchiopods in Austria show that five species still occur at a restricted number of sites in the Pannonian region of Lower Austria. The clam shrimps Leptestheria dahalacensis and Eoleptestheria ticinensis were rediscovered in May 1994 in the flood plains of the river Morava near Marchegg. Imnadia yeyetta and Cyzicus tetracerus have been known to the authors in the same region since 1981, and 1992, respectively. Limnadia lenticularis occurs in the flood plains of the rivers Morava and Danube. Lynceus brachyurus, the only Austrian representative of the Laevicaudata, was not found and most probably got extinct. All Austrian clam shrimp species are considered to be endangered. Main threats are agricultural activities and artificial changes of the hydrologic conditions. Conservational measures are discussed for their effectivity.     

A combined morphological and molecular phylogenetic analysis of Parthenocissus (Vitaceae) and taxonomic implications

Parthenocissus (the Virginia creeper genus, Vitaceae) consists of 13 species and shows a disjunct distribution between Asia and North America. We investigated the inflorescence structure, calyx morphology, appendages on the inner side of petals, leaf epidermis, pollen and seed characters throughout the genus. A combined phylogenetic analysis with 27 morphological and 4137 molecular characters was conducted and the result was largely congruent with that of the previous molecular work, but with higher resolution. The combined analysis identified two clades corresponding to the Asian and North American taxa. Parthenocissus feddei was resolved as closely related to the clade containing P. cuspidifera, P. heterophylla and P. semicordata. The four species share synapomorphies of having conspicuously raised veinlets, an obscurely five‐ (to eight‐) lobed calyx, appendages on the inner side of petals covering the entire length of anthers and foveolate pollen exine ornamentation. Within the Old World clade, the pentafoliolate species were weakly supported as more closely related to species with both simple and trifoliolate leaves. Furthermore, the ancestral states of tendril apices, inflorescence structure, appendages on the inner side of petals and exine ornamentation of pollen grains were reconstructed on the molecular strict consensus tree. The appendages on the inner side of petals and exine ornamentation of pollen grains were suggested to be important characters in the taxonomy of Parthenocissus, especially for species with trifoliolate leaves. Finally, the previous classifications of Parthenocissus were evaluated within the phylogenetic framework. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, ?? , ??–??.     

Breeding systems in the clam shrimp family Limnadiidae (Branchiopoda, Spinicaudata)

Abstract. Crustaceans in the class Branchiopoda exhibit a wide range of breeding systems, including dioecy (gonochorism), androdioecy, parthenogenesis, cyclic parthenogenesis, and hermaphroditism. The largest subgroup of the Branchiopods, the Diplostraca, is reported to encompass all five of these breeding systems. However, many of these reports are based primarily on simple observations of sex ratios in natural populations. Herein we report the beginnings of a more rigorous approach to breeding system determination in the Diplostraca, starting with the family Limnadiidae. We combine measurements of sex ratio, offspring rearings, and behavior to identify three breeding systems within the Limnadiidae: dioecy, androdioecy, and selfing hermaphroditism. To date, no instances of parthenogenetic reproduction have been identified in this family. Comparisons of breeding system determination via simple population sex ratios with our more controlled studies show that simple sex ratios can be useful when these sex ratios are ∼50% males (=dioecy) or 5–30% males (androdioecy). However, population sex ratios of 0–5% males or 35–45% males necessitate further investigation because estimates in these ranges cannot distinguish selfing hermaphroditism from androdioecy or androdioecy from dioecy, respectively. We conclude by noting that the genetic sex-determining system outlined for one of these limnadiid species, Eulimnadia texana , provides a parsimonious framework to describe the evolution of the three breeding systems observed within the Limnadiidae.     

Ultrastructural observations of spermatozoa of several tetragnathid spiders with phylogenetic implications (Araneae, Tetragnathidae)

The present study reports on the ultrastructure of spermatozoa and spermatogenesis of 12 tetragnathid spiders (10 Tetragnatha species [T. boydi, T. dearmata, T. extensa, T. montana, T. nigrita, T. obtusa, T. pinicola, T. reimoseri, T. shoshone, T. striata]; Pachygnatha listeri and Metellina segmentata). All species develop typical cleistospermia with a coiled nucleus in the center and a coiled axoneme in the periphery of the cell. Remarkable differences in the sperm ultrastructure of the investigated species comprise the shape of the main sperm cell components (nucleus, acrosomal complex, implantation fossa, and centriolar complex). Within the observed Tetragnatha species, three types of sperms were characterized: T. montana-type, T. boydi-type, and T. striata-type. The highly derivative T. montana-type is characterized by the following remarkable features: an extremely elongated nucleus, shaped like a corkscrew and twisted around the axoneme (before coiling); a deep implantation fossa; a corkscrew-shaped acrosomal vacuole; after the coiling process, the nucleus is coiled five to six times in the center of the spermatozoon and the axoneme is coiled five to six times peripheral to the nucleus. The T. boydi-type hardly differs from the T. montana-type, but is remarkable due to the triangular-shaped nucleus (in cross section). The T. striata-type differs especially by a peculiar acrosomal vacuole with a long, slightly curved process and a short appendix, as well as a nucleus that describes only three loose coils around the axoneme (before coiling). The spermatozoa of Pachygnatha listeri and especially Metellina segmentata differ strikingly from the described Tetragnatha-types and are similar to more primitive araneomorph spermatozoa, such as Hypochilus pococki. The described Tetragnatha-types completely correspond with Okuma's (1988a,b, J Fac Agr Kyushu U 32:165-181, 32:183-213) classification of Tetragnatha species. Furthermore, our results suggest an early derivative systematic position of Pachygnatha within Tetragnathinae and the position of Metellina within the Tetragnathidae.     

Ultrastructure of the frontal sensory fields in the Lynceidae (Crustacea,Branchiopoda, Laevicaudata)

The clam shrimp family Lynceidae is unusual in possessing paired fields of short setae on either side of the rostral carina. We describe the position of these fields relative to the direction of water movement in live animals as well as the external and internal structure of these setae. The majority of morphological features support a presumed chemosensory role for these sensilla. These features include the lack of a setal socket and the relatively short length of each seta. The low number of enveloping cells (three or four) is uncharacteristic of chemosensory setae and is more typical of mechanoreceptors, as is the absence of any pores on the setae; these characteristics indicate that these fields may have both functions. © 1994 Wiley-Liss, Inc.     

Cephalic morphology of Hymenopus coronatus (Insecta: Mantodea) and its phylogenetic implications

External and internal head structures of the mantodean Hymenopus coronatus are examined and described in detail. The results are elaborately compared with the literature. Strong crests on the anterior tentorial arms that articulate with the subantennal suture, a parietal suture and glossae and paraglossae with anteriorly bent tips are proposed as new potential apomorphies for Mantodea while a head capsule being wider than long, enlarged compound eyes, the presence of a frontal shield or scutellum, lateral lobes in the anterior tentorial arms, the presence of a transverse and an interantennal suture and the reduction of the mentum are confirmed as apomorphies, As potential apomorphies for Dictyoptera the reduction of Musculus tentoriobuccalis lateralis (M. 49) is newly presented and a “perforate” tentorium, lacinial incisivi that are located in a galeal pouch and the presence of a postmola are confirmed. The present study shows the value of cephalic morphology for phylogenetic analysis but also points out that further studies including evolutionary key taxa are essential for resolving the evolutionary adaptations among dictyopterans.     

Organization of the Mitochondrial Genome of Mantis Shrimp Pseudosquilla ciliata (Crustacea: Stomatopoda)

We determined the nearly complete mitochondrial genome of Pseudosquilla ciliata (Crustacea, Stomatopoda), including all protein-coding genes and all but one of the transfer RNAs. There were no gene rearrangements relative to the pattern shared by crustaceans and hexapods. Phylogenetic analysis using concatenated amino acid sequences of the mitochondrial protein-coding genes confirmed a basal position of Stomatopoda among Eumalacostraca. Pancrustacean relationships based on mitogenomic data were analyzed and are discussed in relation to crustacean and hexapod monophyly and hexapod affinities to crustacean subtaxa.