Phylogenetic position of a deep-sea ascidian, Megalodicopia hians, inferred from the molecular data

Ascidians inhabit both shallow water and the deep sea. The phylogenetic position of deep-sea ascidians has not been sufficiently investigated because of their unusual habitats. The family Octacnemidae is one such enigmatic deep-sea ascidian. In this report, we determined the sequences of the 18SrDNA and a mitochondrial protein gene of Megalodicopia hians belonging to the family Octacnemidae, and we analyzed its phylogenetic relationship with other ascidians. A phylogenetic relationship of this family with the families Cionidae and/or Corellidae has been suspected based on a small number of morphological characteristics. However, our results suggested that M. hians has a close relationship to the family Corellidae and might originate from them. This is the first report of the molecular phylogenetic analysis of a deep-sea ascidian.     

A new species of Ditrachybothridium (Cestoda: Diphyllidea) from Galeus sp. (Selachii, Scyliorhynidae) from the south Pacific Ocean, with a revision of the diagnosis of the order, family, and genus and notes on descriptive terminology of microtriches

Ditrachybothridium piliformis is a new species from the spiral intestine of a cat shark, Galeus sp., from the southern Pacific Ocean. This is only the second species assigned to Ditrachybothridium. It differs from the type species D. macrocephalum in lacking spines on the scolex, a character originally used to diagnose the genus. The diagnoses of the Ditrachybothridiidae and of Ditrachybothridium have been revised to reflect this difference. This new species is further differentiated from the type species in its possession of pectinate spinitriches on the tegument of the scolex. The holdfast structures of this species are weakly muscularized, with no membrane-bound layer of radial muscles, indicating that the holdfast structures are bothria rather than bothridia as described in the most recent literature. Several reports for other species have indicated the same situation in other diphyllideans. The diagnosis of the order has been revised to reflect this finding.     

Two new species of Macrobothridium (Cestoda: Diphyllidea) from rhinobatid elasmobranchs in the Gulf of Gabès, Tunisia, with notes on the status of the genus.

As a result of an investigation of metazoan parasites of elasmobranch fishes in the Gulf of Gabès, Tunisia, we discovered 2 new species of diphyllidean cestodes. Macrobothridium euterpes n. sp. is described from the spiral intestine of Rhinobatos rhinobatos, and Macrobothridium syrtensis n. sp. from the spiral intestine of Rhinobatos cemiculus. Macrobothridium euterpes is distinguished from the only other species in the genus (Macrobothridium rhynchobati) by the number of rostellar hooks, size, genital pore position, vagina position, and ovary shape. Macrobothridium syrtensis is distinguished from M. rhynchobati by the hook morphology, testis number, and overall size, and from M. euterpes by the number of rostellar hooks, testis number, genital pore position, vagina position, and ovary shape. These are the first 2 species added to the genus since its establishment in 1989. A standardized formula for representing the number and arrangement of rostellar hooks in diphyllidean species is presented.     

A review of the bacterial flora of teleosts and elasmobranchs, including methods for its analysis

Techniques for the quantitative and qualitative analysis of the commensal bacterial flora of fish are reviewed. The literature concerning the commensal bacterial flora of fish indicates that teleost skin often features 10²–0⁷ organisms per cm² of skin, representing the following taxa, in descending numerical order, Achromobacter, Pseudomonas, Flavo-bacterium and Cytophaga species also coryneform organisms. Actively feeding teleosts appear to have an alimentary canal bacterial flora similar to that of the skin and gills, often there are from 10³–10⁸ organisms per 1.0 g, wet weight, of tissue. According to the limited data available for elasmobranchs Gram–positive bacteria are the predominant component of the bacterial flora on the skin of sharks, though the bacterial flora of North Sea skate ( Raja spp.) is reported as being similar to that of teleosts. The commensal flora of fish, particularly of teleosts, is related to their environment and is influenced by environmental changes that affect the quality of the water. Regular monitoring of the water of commercial fish ponds and aquaria for bacterial quality, temperature, dissolved oxygen concentration and pH, combined with a base–line knowledge of the water's quality, may provide an advanced indication of the presence of bacteria potentially able to produce diseased conditions, and factors that will enhance their growth.     

The phylogenetic position of the Aeolosomatidae and Parergodrilidae, two enigmatic oligochaete-like taxa of the 'Polychaeta', based on molecular data from 18S rDNA sequences

The Aeolosomatidae and the Parergodrilidae are meiofaunal Annelida showing different combinations of clitellate‐like and non‐clitellate character states. Their phylogenetic positions and their systematic status within the Annelida are still in debate. Here we attempt to infer their systematic position using 18S rDNA sequences of the aeolosomatid Aeolosoma sp. and the parergodrilid Stygocapitella subterranea and several other meiofaunal taxa such as the Dinophilidae, Polygordiidae and Saccocirridae. The data matrix was complemented by sequences from several annelid, arthropod and molluscan species. After evaluation of the phylogenetic signal the data set was analysed with maximum‐parsimony, distance and maximum‐likelihood algorithms. Sequences from selected arthropods or molluscs were chosen for outgroup comparison. The resolution of the resulting phylogenies is discussed in comparison to previous studies. The results do not unequivocally support a sister‐group relationship of Aeolosoma sp. and the Clitellata. Instead, depending on the algorithms applied, Aeolosoma clusters in various clades within the polychaetes, for instance, together with eunicidan species, the Dinophilidae, Harmothoë impar or Nereis limbata. The position of Aeolosoma sp. thus cannot be resolved on the basis of the data available. S. subterranea always falls close to a cluster comprising Scoloplos armiger, Questa paucibranchiata and Magelona mirabilis, all of which were resolved as not closely related to both Aeolosoma sp. and the Clitellata. Therefore, convergent evolution of clitellate‐like characters in S. subterranea and hence in the Parergodrilidae is suggested by our phylogenetic analysis. Moreover, the Clitellata form a monophyletic clade within the paraphyletic polychaetes.     

The position of Cetacea within mammalia: phylogenetic analysis of morphological data from extinct and extant taxa

Knowledge of the phylogenetic position of the order Cetacea (whales, dolphins, and porpoises) within Mammalia is of central importance to evolutionary biologists studying the transformations of biological form and function that accompanied the shift from fully terrestrial to fully aquatic life in this clade. Phylogenies based on molecular data and those based on morphological data both place cetaceans among ungulates but are incongruent in other respects. Morphologists argue that cetaceans are most closely related to mesonychians, an extinct group of terrestrial ungulates. They have disagreed, however, as to whether Perissodactyla (odd-toed ungulates) or Artiodactyla (even-toed ungulates) is the extant clade most closely related to Cetacea, and have long maintained that each of these orders is monophyletic. The great majority of molecule-based phylogenies show, by contrast, not only that artiodactyls are the closest extant relatives of Cetacea, but also that Artiodactyla is paraphyletic unless cetaceans are nested within it, often as the sister group of hippopotamids. We tested morphological evidence for several hypotheses concerning the sister taxon relationships of Cetacea in a maximum parsimony analysis of 123 morphological characters from 10 extant and 30 extinct taxa. We advocate treating certain multistate characters as ordered because such a procedure incorporates information about hierarchical morphological transformation. In all most-parsimonious trees, whether multistate characters are ordered or unordered, Artiodactyla is the extant sister taxon of Cetacea. With certain multistate characters ordered, the extinct clade Mesonychia (Mesonychidae + Hapalodectidae) is the sister taxon of Cetacea, and Artiodactyla is monophyletic. When all fossils are removed from the analysis, Artiodactyla is paraphyletic with Cetacea nested inside, indicating that inclusion of mesonychians and other extinct stem taxa in a phylogenetic analysis of the ungulate clade is integral to the recovery of artiodactyl monophyly. Phylogenies derived from molecular data alone may risk recovering inconsistent branches because of an inability to sample extinct clades, which by a conservative estimate, amount to 89% of the ingroup. Addition of data from recently described astragali attributed to cetaceans does not overturn artiodactyl monophyly.     

The embryology ofStegnospermataceae,with a discussion on its status,affinities and systematic position

The embryology ofStegnosperma halimifolium andS. watsonii has been studied in detail. The tapetum is of the secretory type and its cells become multinucleate. Simultaneous cytokinesis in the pollen mother cells follows meiosis. The ripe pollen grains are 3-celled. The ovule is crassinucellate, bitegmic and amphitropous, with the micropyle formed by the inner integument alone. The female archesporium is one celled, and the parietal tissue 3–5 layered. The embryo sac development conforms to thePolygonum type. A central strand, 6 or 7 cells thick, differentiates inside the nucellus and extends from the base of the embryo sac to the chalazal region. The endosperm is nuclear. The embryogeny conforms to the Caryophyllad type. The seed coat is formed by the outer epidermis of the outer integument and the inner epidermis of the inner integument. Based on this evidence and other data, the status of the genus as an independent family,Stegnospermataceae (Stegnospermaceae) is confirmed. Apparently, it forms a connecting link betweenPhytolaccaceae andCaryophyllaceae.     

A synopsis of the neotropical genus Pentaplaris, with remarks on its systematic position within core Malvales

Pentaplaris davidsmithii from Peru and Bolivia andP. huaoranica from Ecuador are described and compared to the only other species previously known in the genus,P. doroteae from Costa Rica. Morphological and palynological characters support the inclusion ofPentaplaris in core Malvales while suggesting that the original assumption that the genus belonged in Tiliaceae-Brownlowieae cannot be maintained.Pentaplaris, which comprises three isolated and evidently rare species, probably belongs to the malvoid-bombacoid alliance, but its position within this clade ramains unresolved.     

Serial passage of the parasite Crithidia bombi within a colony of its host, Bombus terrestris, reduces success in unrelated hosts

In the wild, Bombus spp. bees may contract infections of the trypanosome parasite Crithidia bombi from their nestmates or from others while foraging on contaminated flowers. We expected that as C. bombi is transmitted repeatedly among related workers within a colony, the parasite population would become more successful in this relatively homogeneous host population and less successful in individuals from unrelated colonies of the same or different species. To test our prediction, we serially passaged cocktails of C. bombi strains through workers from the same colony, taking the intensity of infection in related versus unrelated workers as a measure of parasite success at each step in the serial transfer. Using a repeated measures ANOVA, we found the ability of C. bombi to exploit Bombus spp. hosts did not increase within a colony, but did decrease for infections in workers from unrelated colonies. This reduction in success is most likely due to a gradual loss of appropriate C. bombi strains from the infecting the population as the cocktail is 'filtered' during the serial passage within a given colony, without a corresponding increase in overall intensity of the surviving strains.     

The tadpole of Scinax skuki (Anura: Hylidae) from the type locality,with a description of its larval skeleton

Herein, we provide external and internal morphological data of Scinax skuki tadpoles from its type locality. The benthic tadpole of S. skuki has eyes and nostrils positioned dorsally, vent tube dextral and reaching the free margin of the ventral fin, oral disk ventral with posterior margin concave when partially closed, labial tooth row formula 2/3, and the presence of nonpigmented spurs behind the lower jaw. These characters, together with the absence of a tectum parietale, and the shapes of the pars articularis quadrati and suprarostral, are useful for species identification and may be informative for systematic purposes.     

The micropylar plate of the eggs of Phasmida, with a survey of the range of plate form within the order

Eggs of Phasmida are characterized by the presence of a micropylar plate system. The nature of this plate is discussed and the relevance of differences in plate structure to the taxonomy of the order is considered. A survey is made of the range of plate structure throughout the order, covering the external plate structure of 384 species and the internal plate structure of 179 species in forty of the forty-four subgroups of the order.     

Identification and molecular analysis of a multigene family encoding calliphorin, the major larval serum protein of Calliphora vicina

A library of Calliphora vicina genomic DNA was constructed in the λEMBL3 vector and screened for recombinant phages containing chromosomal segments encoding calliphorin, the major larval serum protein (LSP) of Calliphora. A large series of recombinants hybridizing with in vitro labelled poly(A)⁺ RNA from Calliphora larval fat bodies and with specific probes derived from the LSP-1 genes of Drosophila melanogaster was isolated. Five of these phages, chosen at random, were shown by hybrid selection to retain calliphorin mRNA specifically. Eleven calliphorin mRNA-homologous regions were located on restriction maps of these phages by hybridization with 5' end-labelled poly(A)⁺ RNA from Calliphora larval fat bodies. Each phage contains at least two calliphorin genes arranged in direct repeat orientation and seperated by 3.5–5 kb intergenic regions. The genes display similar but not identical restriction patterns. Filter hybridization and heteroduplex analysis indicate that they share a detectable homology with the LSP-1β gene of D. melanogaster. Whole genome Southern analysis showed that these genes belong to a large family of closely related calliphorin genes which were found by in situ hybridization to polytene chromosomes of trichogen cells to be clustered in region 4a of chromosome 2 of Calliphora vicina.     

Paraulopidae and Paraulopus, a new family and genus of aulopiform fishes with revised relationships within the order

A species group hitherto concealed within Chlorophthalmus (Chlorophthalmidae) is described as a new family and genus of Aulopiformes, Paraulopidae and Paraulopus, respectively. Paraulopus clearly belongs in Aulopiformes owing to an enlarged uncinate process on the second epibranchial, the absence of a swimbladder, and fusion of the medial processes of the pelvic girdle, but characterized by having the following combination of characters: the fourth basibranchial with a long tail but no gap separating fourth basibranchial and fifth ceratobranchial, epipleural bones distributed from posterior portion of abdominal vertebra to anterior portion of caudal vertebra, and flesh specimens of most species with paired olive spots dorsally on body. The phylogenetic position of Paraulopus is defined by a cladistic analysis of 101 morphological characters, in 21 genera of Aulopiformes. In a single most parsimonious tree, Paraulopus and Chlorophthalmus are in two different major clades, there being four major clades in all, roughly corresponding to the four suborders of Aulopiformes. Paraulopidae is included in the suborder Synodontoidei. In addition, Bathysauroides is transferred to Chlorophthalmoidei from Giganturoidei, and Bathysauroides and Bathysauropsis are elevated to familial status. Received: January 13, 2001 / Revised: September 27, 2001 / Accepted: October 15, 2001     

Megadraconema cornutum, a new genus and species from Korea, with a discussion of its classification and relationships within the family Draconematidae (Nematoda, Desmodorida) based on morphological and molecular characters

A new genus and species of Draconematidae Filipjev, 1918, Megadraconema cornutum gen. nov., sp. nov., inhabiting subtidal sediments in Jejudo, Korea is described. Megadraconema cornutum gen. nov., sp. nov. is mainly characterized by a long body (1630-2220 μm), presence of a transverse circle of well-developed papillae-like cuticular protrusions at the base of the lip region, a head capsule with reticular structure of subcuticle, an amphid with a pore-like opening, and an internal, bar-shaped fovea. The diagnosis of the family Draconematidae is emended and a key to genus is provided based on their major differential diagnostic characteristics, summarized in a table. Phylogenetic relationships of all the genera within the Draconematidae are discussed for the first time, based on molecular analyses and morphological features. The phylogenetic position of the new genus and relationships within the family Draconematidae based on analysis of molecular sequence data are examined. Analysis of 18S rRNA gene sequences does not support the currently accepted classification, and indicates paraphyly of the subfamily Draconematinae.     

Echinobothrium chisholmae n. sp. (Cestoda,Diphyllidea) from the giant shovel-nose ray Rhinobatos typus from Australia,with observations on the ultrastructure of its scolex musculature and peduncular spines

Echinobothrium chisholmae n. sp. is described from Rhinobatos typus Bennett (Rhinobatidae), collected from Heron Island, Great Barrier Reef, Australia. E. chisholmae differs from all congeners in possessing 11 hooks in each dorsal and ventral group on the rostellum and groups of 3-6 hooklets on either side of the hooks. A single metacestode of E. chisholmae was collected from the decapod crustacean Penaeus longistylus Kubo. Yellow pigmentation of the cephalic peduncle in immature adults is caused by the accumulation of large vesicles in the distal cytoplasm of the tegument. The vesicles probably provide materials for spine formation. Ultrastructural examination of the rostellar musculature revealed that the muscles are stratified (striated-like), consisting of a periodic repetition of sarcomeres separated by perforated Z-like lines that are oblique to the long axes of the myofilaments.     

Furcarcturus polarsterni gen. nov., sp. nov., a large deep-sea arcturid isopod from the Drake Passage, with a preliminary molecular characterization

A new arcturid species of unusual size (> 6 cm) is described from a locality in the Drake Passage at 3720 m depth. Due to the unique combination of characters found in these isopods, the new genus Furcarcturus is proposed. Sequences of the 16S rRNA gene obtained from eight species indicate that the new species does not belong to groups of species currently placed in the genera Antarcturus and Chaetarcturus. More sequences are needed to corroborate arcturid phlylogeny. Accepted: 28 May 2000