Phylogenetic analysis of the Brachyura (Crustacea, Decapoda) based on characters of the foregut with establishment of a new taxon

The Brachyura, within the decapod crustaceans, is one of the most species-rich taxa with up to 10 000 species. However, its phylogenetic history, evolution and fossil record remain subjects of controversy. In our study, we examined the phylogenetic relationships of the Brachyura based on morphological characters of the foregut. The cladistic analysis supports a monophyletic Brachyura including the Dromiidae and Raninidae. A clade comprising Dromiidae and Dynomenidae forms the most basal assemblage within the Brachyura, followed by the Homolidae and Latreilliidae. As a result, neither Podotremata nor Archaeobrachyura form a clade. In contrast, foregut data suggest that the classical taxon Oxystomata, comprising Calappidae, Parthenopidae, Dorippidae, Leucosiidae, Cymonomidae and Raninidae, is monophyletic. This makes the Heterotremata paraphyletic or polyphyletic. A newly established taxon, Neobrachyura, embraces some representatives of the Heterotremata and the monophyletic Thoracotremata.     

Morphology of the female reproductive system of three dorippid crabs (Crustacea: Decapoda: Brachyura: Dorippidae) and the role of accessory cuticle structures associated with seminal receptacles

The reproductive systems of crabs reveal characters of considerable importance for the understanding of brachyuran phylogeny and evolution. The Dorippoidea show several plesiomorphic characters within Eubrachyura and similarities to podotreme crabs. Hence, they are often considered as an early diverging lineage, sometimes even as the sister group to all remaining eubrachyurans. Due to their role as prime candidates for putative plesiomorphic characters of the reproductive system of the Eubrachyura, we compared the morphology of the vaginae, seminal receptacles, and ovaries of three dorippid species using histological methods, micro‐computed tomography, and 3‐D reconstructions. Despite the putative phylogenetic position of dorippids, the female reproductive system shows features that are regarded as derived characters in eubrachyurans, including a concave vagina and a ventral‐type seminal receptacle. In contrast to other eubrachyurans, the oviduct does not enter the seminal receptacle directly but through specific cuticular valves. The female reproductive systems of Dorippe sinica and Dorippe quadridens are remarkable in further aspects. The seminal receptacles of both species are completely cuticle‐lined and have accessory sperm storage structures, the bursae. Our findings on the morphology of the female reproductive system of dorippids with its unique combination of basal, derived, and new characters challenges the prevailing hypothesis on the evolution of sperm storage organs in Eubrachyura.     

Phylogeny of Decapoda using two nuclear protein-coding genes: origin and evolution of the Reptantia

The phylogeny of Decapoda is contentious and many hypotheses have been proposed based on morphological cladistic analyses. Recent molecular studies, however, yielded contrasting results despite their use of similar data (nuclear and mitochondrial rDNA). Here we present the first application of two nuclear protein-coding genes, phosphoenolpyruvate carboxykinase and sodium-potassium ATPase alpha-subunit, to reconstruct the phylogeny of major infraorders within Decapoda. A total of 64 species representing all infraorders of Pleocyemata were analyzed with five species from Dendrobranchiata as outgroups. Maximum likelihood and Bayesian inference reveal that the Reptantia and all but one infraorder are monophyletic. Thalassinidea, however, is polyphyletic. The nodal support for most of the infraordinal and inter-familial relationships is high. Stenopodidea and Caridea form a clade sister to Reptantia, which comprises two major clades. The first clade, consisting of Astacidea, Achelata, Polychelida and three thalassinidean families (Axiidae, Calocarididae and Eiconaxiidae), corresponds essentially to the old taxon suborder Macrura Reptantia. Polychelida nests within Macrura Reptantia instead of being the most basal reptant as suggested in previous studies. The high level of morphological and genetic divergence of Polychelida from Achelata and Astacidea justifies its infraorder status. The second major reptant clade consists of Anomura, Brachyura and two thalassindean families (Thalassinidae and Upogebiidae). Anomura and Brachyura form Meiura, with moderate support. Notably thalassinidean families are sister to both major reptant clades, suggesting that the stem lineage reptants were thalassinidean-like. Moreover, some families (e.g. Nephropidae, Diogenidae, Paguridae) are paraphyletic, warranting further studies to evaluate their status. The present study ably demonstrates the utility of nuclear protein-coding genes in phylogenetic inference in decapods. The topologies obtained are robust and the two molecular markers are informative across a wide range of taxonomic levels. We propose that nuclear protein-coding genes should constitute core markers for future phylogenetic studies of decapods, especially for higher systematics.     

Phylogenetic implications of sperm storage in Podotremata: Histology and 3D‐reconstructions of spermathecae and gonopores in female carrier crabs (Decapoda: Brachyura: Homoloidea)

Female reproductive systems are important characters for understanding the evolution of Brachyura and resolving its phylogenetic relationships. We herein investigate a podotreme brachyuran reproductive system comprehensively for the first time studying spermathecae and gonopores of Homoloidea with histological methods, micro‐computer tomography and scanning electron microscopy. Our results show that spermathecal apertures are species‐specific and their shape corresponds closely to that of male copulatory organs. Apertures were either enclosed by membranous cuticle areas or otherwise occluded preventing direct access into spermathecae. 3D‐reconstructions reveal that spermathecae differ between the species Paromola cuvieri and Homola barbata with regard to the involvement of sternite 7 and 8, respectively, in forming the sperm storage chamber. The cuticle epithelium that lines the spermathecal chamber is irregular and distinct from the remaining cylindrical cuticle epithelium. A first uniramous pleopod was present in all homoloids studied and always held in a position to cover spermathecal apertures. Specific pulvinated cuticle structures present on both sides of the first pleopod are herein interpreted as adhesive structures functioning in reproductive processes. The coxal gonopores were enclosed by a laterally arising muscular mobile operculum that resembles opercula described in eubrachyuran vaginae, which raises the question whether these two structures are homologous. Our results are compared with data available for other brachyuran groups and discussed in terms of phylogenetic relationships within the Brachyura and possible functions in insemination and fertilization in Podotremata. J. Morphol. 278:89–105, 2017. ©© 2016 Wiley Periodicals,Inc.     

The oldest higher true crabs (Crustacea: Decapoda: Brachyura): insights from the Early Cretaceous of the Americas

Despite the extensive fossil record of higher crabs (Eubrachyura) from Late Cretaceous and Cenozoic rocks worldwide, their Early Cretaceous occurrences are scarce and fragmentary, obscuring our understanding of their early evolution. Until now, representatives of only two families of eubrachyuran‐like crabs were known from the Early Cretaceous: Componocancridae and Tepexicarcinidae fam. nov., both monospecific lineages from the Albian (~110–100 Ma) of North and Central America, respectively. The discovery of Telamonocarcinus antiquus sp. nov. (Telamonocarcinidae) from the early Albian of Colombia, South America (~110 Ma), increases to three the number of known Early Cretaceous eubrachyuran‐like families. The ages and geographical distributions of the oldest eubrachyuran‐like taxa (i.e. Componocancridae, Telamonocarcinidae and Tepexicarcinidae fam. nov.) suggest that the oldest higher true crabs might have originated in the Americas; that they were already morphologically diverse by the late Early Cretaceous; and that their most recent common ancestor must be rooted in the Early Cretaceous, or even the Late Jurassic.     

Characterization of the complete mitochondrial genome of Uca lacteus and comparison with other Brachyuran crabs

Brachyuran crabs comprise the most species-rich clade among the crustacean order Decapoda and are divided into several major superfamilies. However, the monophyly of the superfamilies Ocypodoidea and Grapsoidea in their current compositions within the Brachyura remains inconclusive. In this study, the complete mitochondrial genome (mitogenome) of Uca lacteus (Ocypodoidea, Ocypodidae) was sequenced, annotated, and compared with those of other Brachyuran crabs. The circular mitogenome of U. lacteus is 15,661 base pairs long and contains the entire set of 37 genes and an A + T-rich region typically observed in decapod mitogenomes. Secondary structures of several tRNAs are partly missing (trnS1), and the number of bases is significantly decreased (trnD and trnF), as discovered in many other metazoans. We compared the gene order of U. lacteus with other species of Ocypodidae and found that they are consistent. The gene rearrangement of Ocypodidae is also identical to that of the ancestor of Brachyura. However, the order of the trnH gene varies from the rearrangement of ancestral Decapoda. Accordingly, we hypothesized that this rearrangement of trnH underwent a translocation during the evolution from Decapoda to Brachyura. The phylogenetic relationship of the 81 Brachyura species and one outgroup was recovered based on 13 protein-coding genes. This analysis confirmed that U. lacteus belongs to the family Ocypodidae and established a paraphyletic relationship between Ocypodoidea and Grapsoidea.     

Relationship of Homolidae and Dromiidae: Evidence from Spermatozoal Ultrastructure (Crustacea,Decapoda)

Abstract The homolid spermatozoon, as exemplified by Homolasp., Paromolasp. and Paromola petterdi, differs markedly from spermatozoa of crabs of the Heterotremata–Thoracotremata assemblage but agrees with the sperm of dromiids, in the strongly anteroposteriorly depressed acrosome (apomorphy?) and the capitate form of the perforatorium (a major synapomorphy seen nowhere else in the Crustacea). These similarities support inclusion of the Dromiidae and Homolidae in a single grouping, the Podotremata. The homolid perforatorium differs from that of dromiids in the autapomorphic spiked–wheel form of the anterior expansion. Homolid spermatozoa show nuclear arms symplesiomorphic of all investigated crabs (small or questionably sometimes absent in Dromiidae), and corresponding loss of purely microtubular arms seen in other reptants. Homolid sperm agree with those of dromiids (synapomorphy?), raninids, higher heterotremes and thoracotremes (homoplasies?) but differ from lower heterotremes, in lacking microtubules in the nuclear arms. A posterior median process of the nucleus in homolids, not seen in dromiids, is shared with anomurans and lower heterotremes. No features in the ultrastructure of homolid or dromiid sperm have been detected which associate them exclusively with either the Raninidae or the heterotreme and thoracotreme Brachyura.     

A hypothesis about the origin of sperm storage in the Eubrachyura, the effects of seminal receptacle structure on mating strategies and the evolution of crab diversity: How did a race to be first become a race to be last?

The origins and evolution of sperm storage in Brachyura are enigmatic: sperm is either stored in seminal receptacles, accessible via the vulvae on the sixth thoracic sternite, or in spermathecae at the border between the seventh and eighth sternites. Crabs with spermathecae are collectively referred to as “podotremes” while crabs with seminal receptacles belong to the Eubrachyura. The position of gonopores is the primary basis for subdividing the Eurachyura into the Heterotremata (female vulvae + males with coxal gonopores) and Thoracotremata (female vulvae + males with sternal gonopores). We present a hypothesis about the evolution of seminal receptacles in eubrachyuran female crabs and argue that the sternal gonopore has been internalized into chitin-lined seminal receptacles and the vulva is in fact a secondary aperture. The loss of some or all of the ancestral chitinous seminal receptacle lining was linked to ventral migration of the oviduct connection. Male and female strategies are to maximize gamete fertilization. The most important variable for females is sperm supply, enhanced by long-term storage made possible by the seminal receptacle. To maximize their fertilization rates males must adapt to the structure of the seminal receptacle to ensure that their sperm are close to the oviduct entrance. The major evolutionary impetus for female mating strategies was derived from the consequences of better sperm conservation and the structure of the seminal receptacle. The advantages were all to the females because their promiscuity and sperm storage allowed them to produce more genetically variable offspring, thereby enhancing variation upon which natural selection could act. We extend our arguments to Brachyura as a whole and offer a unifying explanation of the evolution of seminal receptacles, comparing them with the spermathecae found in “Podotremata”: they were independent solutions to the same problem: maintaining sperm supply during evolutionary carcinization.Explanation of eubrachyuran mating strategies requires analysis of the mating–moulting link, indeterminate vs. determinate growth format and seminal receptacle structure. Two alternatives for each of these characters means that there are eight possible outcomes. Six of these outcomes have been realized, which we term Portunoid, Majoid, Eriphoid, Xanthoid, Cancroid, and Grapsoid–Ocypodoid strategies, respectively. Mapping these characters on to a workable phylogeny (wherein some changes to the seminal receptacle + moulting–mating links are assumed to have occurred more than once) produces the following relationships: Portunoids + Majoids are a sister group to the rest of the Eubrachyura, which fall into two sister groups, Eriphoids + Xanthoids and Cancroids + Grapsoid–Ocypodoids and the “Podotremata” is sister group to all the Eubrachyura. We conclude that what began as a race to be the first to mate was turned on its head to become a race to be last, by the evolutionary changes to the seminal receptacle. Eubrachyuran females were advantaged by greater reproductive autonomy, more opportunity to mate with other males, resulting in more genetically variable progeny and leading to the evolution of much greater taxonomic diversity compared to “podotremes”.     

Morphology of the genital ducts in female crabs

The Brachyura may be separated into two groups by the position of the female genital openings. In the superfamilies Gymnopleura and Dromiacea they open on the coxae of the third peraeopods, while in the Oxystomata, Corystoidea, Brachyrhyncha and Oxyrhyncha they open on the sternum of the corresponding segment. This paper deals with the structure of the genital duets in females of the latter group. Each duct, leading from the ovary to the exterior, consists of four regions—oviduct, spermatheca, vagina and vulva. Two basic patterns of duct, simple and concave, are recognized by variations in the structure of the vagina. Each may be elaborated by the presence of an operculum closing the vulva. These are described by chosen examples, and some of the changes associated with the breeding cycle are detailed. The distribution of the two patterns of duet in the various families of Brachyura is examined, and the phylogenetic implications considered. The more important of these are that the Corystoidea is rightly designated a distinct superfamily, and that the Corystoidea-Portunidae line forms the basic stock of the Brachyura with sternal female openings.     

Paradorippe granulata – A crab with external fertilization and a novel type of sperm storage organ challenges prevalent ideas on the evolution of reproduction in Eubrachyura (Crustacea: Brachyura: Dorippidae)

Two fundamentally different sperm storage organs occur in Brachyura. The probably paraphyletic podotremes show intersegmental spermathecae, which are distant from oviducts and coxal gonopores. Hence, fertilization is external. In contrast to this, the seminal receptacles of Eubrachyura are directly connected with the ovaries. Thus, at least initial fertilization is internal. This pattern has been interpreted as an apomorphy of Eubrachyura. To test this hypothesis, we studied the morphology of the reproductive organs of Paradorippe granulata, a representative of the putatively early diverging eubrachyuran lineage Dorippoidea. Applying histology, 3D-reconstructions and micro-computed-tomography we revealed a novel type of sperm storage organ. Female P.granulata lack the characteristic eubrachyuran seminal receptacle. Instead sperm is stored in four cuticle-lined bursae, two on each side of the paired oviducts. The elaborate bulbous male gonopod with several terminal processes is adapted to transferring sperm into the female twin bursae. Since oviducts and twin bursae are not directly connected, spermatozoa and oocytes mix when gametes pass through the sternal vulva. Thus, fertilization in P.granulata is external. Our finding of a eubrachyuran crab that lacks seminal receptacles and exhibits external fertilization calls prevailing concepts on the evolution of sperm storage in Eubrachyura into question.     

Characterization of the exoskeleton of the Antarctic king crab Paralomis birsteini

Ocean acidification is projected to inhibit the biogenic production of calcium carbonate skeletons in marine organisms. Antarctic waters represent a natural environment in which to examine the long‐term effects of carbonate undersaturation on calcification in marine predators. King crabs (Decapoda: Anomura: Lithodidae), which currently inhabit the undersaturated environment of the continental slope off Antarctica, are potential invasives on the Antarctic shelf as oceanic temperatures rise. Here, we describe the chemical, physical, and mechanical properties of the exoskeleton of the deep‐water Antarctic lithodid Paralomis birsteini and compare our measurements with two decapod species from shallow water at lower latitudes, Callinectes sapidus (Brachyura: Portunidae) and Cancer borealis (Brachyura: Cancridae). In Paralomis birsteini, crabs deposit proportionally more calcium carbonate in their predatory chelae than their protective carapaces, compared with the other two crab species. When exoskeleton thickness and microhardness were compared between the chelae and carapace, the magnitude of the difference between these body regions was significantly greater in P. birsteini than in the other species tested. Hence, there appeared to be a greater disparity in P. birsteini in overall investment in calcium carbonate structures among regions of the exoskeleton. The imperatives of prey consumption and predator avoidance may be influencing the deposition of calcium to different parts of the exoskeleton in lithodids living in an environment undersaturated with respect to calcium carbonate.     

The Entire Mitochondrial Genome of Macrophthalmus abbreviatus Reveals Insights into the Phylogeny and Gene Rearrangements of Brachyura

Brachyuran crabs comprise the most species-rich clades among extant Decapoda and are divided into several major superfamilies. However, the phylogeny of Brachyuran remains controversial, comprehensive analysis of the overall phylogeny is still lacking. Complete mitochondrial genome (mitogenome) can indicate phylogenetic relationships, as well as useful information for gene rearrangement mechanisms and molecular evolution. In this study, we firstly sequenced and annotated the complete mitogenome of Macrophthalmus abbreviatus (Brachyura; Macrophthalmidae). The mitogenome length of M. abbreviatus is 16,322 bp, containing the entire set of 37 genes and a control region typically observed in Brachyuran mitogenomes. The genome composition of M. abbreviatus was highly A+T biased 76.3% showing positive AT-skew (0.033) and negative GC-skew (??0.351). In M. abbreviatus mitogenome, most tRNA genes were folded into the clover-leaf secondary structure except trnH, trnS1 and trnC, which was similar to the other species in Macrophthalmidae. Phylogenetic analysis showed that all families form a monophyletic, and Varunidae and Macrophthalmidae clustered into a monophyletic clade as sister groups. Comparative analyses of rearrangement among Brachyura revealed that Varunidae (Grapsoidea) and Macrophthalmidae (Ocypodoidea) had the same gene order, which reinforced the result of phylogeny. The combined results of two aspects revealed that the polyphyly of Ocypodoidea and Grapsoidea were well supported. In general, the results obtained in this research will contribute to further studies on molecular based for the classification and gene rearrangements of Macrophthalmidae or even Brachyura.

     

Utility of arginine kinase for resolution of phylogenetic relationships among Brachyuran genera and families

The molecular phylogenetics of decapod crustaceans has been based on sequence data from a limited number of genes. These have included rapidly evolving mitochondrial genes, which are most appropriate for studies of closely related species, and slowly evolving nuclear ribosomal RNA genes, which have been most useful for resolution of deep branches within the Decapoda. Here we examine the utility of the nuclear gene that encodes arginine kinase for phylogenetic reconstruction at intermediate levels (relationships among genera and families) within the decapod infraorder Brachyura (the true crabs). Analyses based on arginine kinase sequences were compared and combined with those for the mitochondrial cytochrome oxidase I gene. All of the genera in our taxon sample were resolved with high support with arginine kinase data alone. However, some of these genera were grouped into clades that are in conflict with recognized brachyuran families. A phylogeny based on cytochrome oxidase I was consistent with the arginine kinase phylogeny, but with weaker support. A recently proposed measure of phylogenetic informativeness indicated that arginine kinase was generally more informative than cytochrome oxidase I for relationships above the level of genus. Combined analysis of data from both genes provided strong support for clades that are in conflict with current assignments of genera to the families Epialtidae, Mithracidae, Pisidae, and Portunidae.     

Phylogeny of the mega-diverse Gelechioidea (Lepidoptera): adaptations and determinants of success

The Gelechioidea, with 18,000 described and many more unnamed species ranks among the most diverse lepidopteran superfamilies. Nevertheless, their taxonomy has remained largely unresolved, and phylogenetic affinities among gelechioid families and lower taxa have been insufficiently understood. We constructed, for the first time, a comprehensive molecular phylogeny for the Gelechioidea. We sampled seven genes, in total 5466 base pairs, of 109 gelechioid taxa representing 32 of 37 recognized subfamilies, and two outgroup taxa. We used maximum likelihood methods and Bayesian inference to construct phylogenetic trees. We found that the families Autostichidae, Lecithoceridae, Xyloryctidae, and Oecophoridae s. str., in this order, are the most basally arising clades. Elachistidae s. l. was found to be paraphyletic, with families such as Gelechiidae and Cosmopterigidae nested within it, and Parametriotinae associated with several families previously considered unrelated to them. Using the phylogenetic trees, we examined patterns of life history evolution and determinants of the success of different lineages. Gelechioids express unusually wide variability in life-history strategies, including herbivorous, saprophagous, fungivorous, and carnivorous lineages. Most species are highly specialized in diet and other life history traits. The results suggest that either saprophagy was the ancestral feeding strategy from which herbivory evolved independently on multiple occasions, or that the ancestor was herbivorous with repeated origins of saprophagy. External feeding is an ancestral trait from which internal feeding evolved independently several times. In terms of species number, saprophages are dominant in Australia, while elsewhere several phytophagous lineages have extensively specialized and diversified. Internal feeding has remained a somewhat less generally adopted feeding mode, although in a few lineages significant radiations of leaf mining species have occurred. We conclude that diverse feeding modes, specialization among saprophages, repeated shifts to phytophagy, and a generally high specialization rate on single plant species (monophagy) are the major factors behind the success of the Gelechioidea.     

Physiological responses of three crustacean species to infection by the dinoflagellate-like protist Hematodinium (Alveolata: Syndinea)

This is the first study comparing physiological responses of three decapod species to infection by parasites of the genus Hematodinium, which belongs to the dinoflagellate-like Syndinea. Responses varied profoundly between the crabs Carcinus maenas and Cancer pagurus (Brachyura), but also differed to those of hermit crabs, Pagurus bernhardus (Anomura). Osmoregulatory capacity was reduced significantly in Hematodinium-infected C. maenas, haemolymph pH increased in parasitised C. pagurus and P. bernhardus, and L-lactate concentration decreased in infected P. bernhardus. Changes to tissues and exoskeletons were observed in C. pagurus, but not in C. maenas and P. bernhardus.     

Molecular evolution of hemoglobins of antarctic fishes (Notothenioidei)

Amino acid sequences of α- and β-chains of human hemoglobin and of hemoglobins of coelacanth and 24 teleost fish species, including 11 antarctic and two temperate Notothenioidei, were analyzed using maximum parsimony. Trees were derived for the α- and β-chains separately and for tandemly arranged sequences, using the human and coelacanth sequences as outgroups in all analyses. The topologies of the trees of the α-and β-chains are highly congruent and indicate a specific pattern of gene duplications and gene expression of teleost hemoglobins which has not yet been investigated into more detail. The Notothenioid fish generally contain a single major hemoglobin and often a second minor component. The α- and β-chains of the major components form a monophyletic group in all investigated trees, with the nonantarctic Pseudaphritis as their sister taxon. The minor chains also are a monophyletic group and form an unresolved cluster with the major chains and the hemoglobins of tuna and red gurnard. The Notothenioid families Nototheniidae and Bathydraconidae appear to be paraphyletic. Received: 26 March 1997 / Accepted: 7 May 1997     

Behavioral and morphological aspects of decorating in Oregonia gracilis (Brachyura: Majoidea)

Abstract. Decorator crabs (Brachyura: Majoidea) are known for attaching sessile organisms to specialized velcro-like hooked setae. Here we describe behavioral and morphological aspects of decorating for a common northern Pacific majoid, Oregonia gracilis . Members of O. gracilis decorate with a diverse array of sessile organisms. These are attached to hooked setae, and also physically interact with long, pappose setae that occur in the same body regions as hooked setae. We describe these pappose setae and document the occurrence of similar setae in 36 other decorating majoids across seven families. In O. gracilis , the density of pappose and hooked setae independently covary with decoration amount, which is sexually dimorphic—juveniles and adult females decorate heavily, whereas adult males decorate sparsely. Adult males have reduced numbers of hooked and pappose setae, but the ontogenetic patterns for the two setal types are different, suggesting that they are quasi-independent characters. We experimentally ablated pappose setae to ask if they functionally contribute to decorating in O. gracilis . Surprisingly, we found that pappose setae are not necessary for decorating under laboratory conditions. Pappose setae could play an auxiliary mechanical role or a sensory role in decorating, or may have another as-yet-unidentified function distinct from decorating.     

A Preliminary Molecular Phylogeny of Planthoppers (Hemiptera: Fulgoroidea) Based on Nuclear and Mitochondrial DNA Sequences

The planthopper superfamily Fulgoroidea (Insecta: Hemiptera) is one of the most dominant groups of phytophagous insects. It comprises about 20 families, containing a total of 9000 species worldwide. Despite several recent studies, the phylogeny of Fulgoroidea is not yet satisfactorily resolved and the phylogenetic positions of several key families, especially Cixiidae, Delphacidae, Tettigometridae, Nogodinidae, Acanaloniidae and Issidae, are contentious. Here, we expand upon recent phylogenetic work using additional nuclear (18S and 28S) and novel mitochondrial (16S and cytb) markers. Maximum likelihood and Bayesian analyses yielded robust phylogenetic trees. In these topologies, a group containing Cixiidae and Delphacidae is recovered as the sister group to the remaining taxa. Tettigometridae is placed in a more nested position and is grouped with Caliscelidae. Sister relationships are found between Flatidae and Ricaniidae, and between Dictyopharidae and Fulgoridae. Nogodinidae and Issidae are confirmed to be non-monophyletic families. For major nodes of interest, divergence date estimates are generally older than those from the fossil record.     

Effect of acanthocephalan parasites on hiding behaviour in two species of shore crabs

The effect of acanthocephalan parasites (Profilicollis spp.) on the hiding behaviour during low tide of two species of shore crabs (intermediate hosts), Macrophthalmus hirtipes (Brachyura: Ocypodidae) and Hemigrapsus crenulatus (Brachyura: Grapsidae), was examined at Blueskin Bay, South Island, New Zealand. Exposed M. hirtipes were found to have significantly higher infection levels than did hidden conspecifics. This pattern was not observed for H. crenulatus. Mean cystacanth numbers were found to be considerably higher in M. hirtipes than H. crenulatus. Crabs exposed at low tide are at a greater risk of predation by definitive shorebird hosts than are hidden conspecifics. Preferential manipulation of one intermediate host species over another could influence diversity within ecosystems.     

Quantifying the Effects of Green Crab Damage to Eelgrass Transplants

Mesocosm experiments were conducted in the summer of 1996 to quantify the effect of bioturbation by Carcinus maenas (the introduced European green crab) on survival of transplanted Zostera marina (eelgrass). The research grew out of a successful 2.52 ha eelgrass transplant project in the Great Bay Estuary of New Hampshire. At several subtidal sites, green crabs were found to damage transplanted eelgrass by cutting the shoots to the extent that some sites demonstrated poor survival. In three separate experiments, eight replicate mesocosm tanks were transplanted with 36 shoots of eelgrass, and different crab densities were introduced into the tanks. The number of shoots damaged by crabs was significantly higher in tanks with moderate (4.0 crabs/m²), high (7.0 crabs/m²), or very high (15.0 crabs/m²) crab densities than in tanks with low (1.0 crabs/m²) crab densities. Up to 39% of viable shoots were lost within one week of exposure to green crab activities. The mesocosm results demonstrated that green crabs were not directly attracted to eelgrass but that they significantly decreased transplant survival through their activity. Field densities of green crabs were found to exceed the density at which most damage occurred in the experiments, suggesting that this introduced species can be a major determinant of eelgrass transplant survival. The results underscore the major influence that biological components of transplant sites can have on transplant survival, and the need for their consideration in the site selection process.