Molecular phylogeny of Anomalodesmata (Mollusca: Bivalvia) inferred from 18S rRNA sequences

The origin of the anomalodesmatan bivalves and the relationships of the constituent families are far from being settled. Phylogenetic uncertainties result from the morphological heterogeneity of the Anomalodesmata and from parallel/convergent evolution of several character complexes due to similar life habits. Here, we assess these problems with 26 near-complete anomalodesmatan 18S rRNA sequences from 12 out of 15 families and a selection of heteroconch outgroup taxa. The robustly monophyletic Anomalodesmata share insertions in the V2 and V4 expansion regions. Both parsimony and maximum-likelihood analyses confirm their position among the basal heterodonts rooting between Carditidae and Lucinidae or, together with the latter, between Carditidae and the remaining Heterodonta. There is no support for monophyletic Myoida, nor for a close relationship of Anomalodesmata with any myoid taxon. At the base of the Anomalodesmata is an unstable cluster of long-branch species belonging to the Poromyidae, Verticordiidae, Lyonsiellidae and Thraciidae. The remaining Anomalodesmata split consistently but with varying branch support into three major clades: the Cuspidariidae excluding Myonera ; a 'thraciid' clade consisting of (Euciroidae, ( Myonera ( Thracia, Cleidothaerus , Myochamidae))); and a 'lyonsiid' clade with Laternulidae, Pandoridae, diphyletic Lyonsiidae due to a robust clade of Lyonsia norwegica and the clavagellid Brechites vaginiferus . Tests of various alternative topologies showed that all are significantly longer but optimal likelihood trees with monophyletic carnivorous taxa and/or Thraciidae are not significantly less likely. These results differ greatly from previous morphological studies. Palaeontological data and homology decisions for selected characters are evaluated in the light of the molecular trees.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 229–246.     

A cladistic phylogeny of the family Patellidae (Mollusca: Gastropoda)

A phylogenetic hypothesis for the patellid limpets is reconstructed by cladistic analysis of morphological characters from 37 species, representing all but one of the living members of the family. Characters included in the analysis are derived from shell shape and microstructure, headfoot and pallial complex, radula and sperm. The species fall into four clades, providing the basis for a new phylogenetic classification into four monophyletic genera: Helcion (four species; southern Africa), Cymbula (eight species; southern Africa, eastern Atlantic, southern Indian Ocean), Scutellastra (17 species; southern and southwestern Africa, Australia, Indo-West Pacific, Eastern Pacific) and Patella (nine species; northeastern Atlantic and Mediterranean). The analysis suggests sister-group relationships between Helcion and Cymbula, and between Scutellastra and Patella. In combination with present-day patterns of geographical distribution, this phylogenetic hypothesis is used to discuss the historical biogeography of the Patellidae. Scutellastra may have originated in southern Africa and dispersed across the Pacific, or alternatively may be a primitively Tethyan group. Both Helcion and Cymbula appear to have originated in southern Africa, but three Cymbula species have dispersed respectively to northwest Africa, St Helena and the southern Indian Ocean. The patellids of the northeastern Atlantic form a single clade, Patella (including P. pellucida), which may have arrived by northward dispersal of an ancestor from southern Africa, or possibly by vicariance of a widespread ancestral Tethyan distribution. The known fossil record of patellids is too fragmentary to permit choice between these alternatives.     

18S ribosomal RNA gene sequences of Cochliopodium (Himatismenida) and the phylogeny of Amoebozoa

Cochliopodium is a very distinctive genus of discoid amoebae covered by a dorsal tectum of carbohydrate microscales. Its phylogenetic position is unclear, since although sharing many features with naked "gymnamoebae", the tectum sets it apart. We sequenced 18S ribosomal RNA genes from three Cochliopodium species (minus, spiniferum and Cochliopodium sp., a new species resembling C. minutum). Phylogenetic analysis shows Cochliopodium as robustly holophyletic and within Amoebozoa, in full accord with morphological data. Cochliopodium is always one of the basal branches within Amoebozoa but its precise position is unstable. In Bayesian analysis it is sister to holophyletic Glycostylida, but distance trees mostly place it between Dermamoeba and a possibly artifactual long-branch cluster including Thecamoeba. These positions are poorly supported and basal amoebozoan branching ill-resolved, making it unclear whether Discosea (Glycostylida, Himatismenida, Dermamoebida) is holophyletic; however, Thecamoeba seems not specifically related to Dermamoeba. We also sequenced the small-subunit rRNA gene of Vannella persistens, which constantly grouped with other Vannella species, and two Hartmannella strains. Our trees suggest that Vexilliferidae, Variosea and Hartmannella are polyphyletic, confirming the existence of two very distinct Hartmannella clades: that comprising H. cantabrigiensis and another divergent species is sister to Glaeseria, whilst Hartmannella vermiformis branches more deeply.     

Phylogenetic relationships among six vetigastropod subgroups (Mollusca, Gastropoda) based on 18S rDNA sequences

Complete 18S rDNA sequences were determined for 10 vetigastropods in order to investigate the phylogeny of Vetigastropoda, which is controversial. These sequences were analyzed together with published sequences for nine other vetigastropods and two nerites. With the two nerites as outgroups, the phylogeny was inferred by three analytical methods, neighbor-joining, maximum likelihood, and maximum parsimony. The 18S rDNA sequence data support the monophyly of four vetigastropod superfamilies, the Pleurotomarioidea, the Fissurelloidea, the Haliotoidea, and the Trochoidea. The present results yield the new branching order: (Pleurotomarioidea (Fissurelloidea ((Scissurelloidea, Lepetodriloidea) (Haliotoidea, Trochoidea)))) within the vetigastropod clade.     

The phylogeny and taxonomy of austral monodontine topshells (Mollusca: Gastropoda: Trochidae), inferred from DNA sequences

The systematics of topshells (family Trochidae) is currently unresolved: at present even the generic boundaries within this group are poorly defined. In this study, we used sequence data of two mitochondrial genes (16S and cytochrome oxidase 1, COI) and one nuclear gene (actin) to resolve the phylogeny of a closely related subgroup of the Trochidae, 30 species of largely Southern Hemisphere monodontine topshells. The phylogenies constructed revealed five well-supported generic clades: a South African clade (genus Oxystele Philippi, 1847), which lay basally to four internal Pacific clades (genera Chlorodiloma Pilsbry, 1889; Monodonta Lamarck, 1799; Austrocochlea Fischer, 1885; and Diloma Philippi, 1845). The molecular phylogenies constructed in this study shed light on previously unresolved relationships between different groups of topshells, allowing for the first time assignation (based on DNA sequence) of clearly defined, well-supported taxonomic and nomenclatural classification of monodontine topshells species. Austrocochlea crinita (Philippi, 1849), A. odontis (Wood, 1828), A. adelaidae (Philippi, 1849), and A. millelineata (Bonnet, 1864) are placed in the genus Chlorodiloma, which we resurrect from synonymy with Austrocochlea. The Japanese M. confusa Tapparone-Canefri, 1874 is treated as a separate species from M. labio (Linné, 1758). Melagraphia Gray, 1847 is synonymised with Diloma and its sole member, M. aethiops (Gmelin, 1791), along with A. concamerata (Wood, 1828), is transferred to that genus. The Juan Fernandez endemic D. crusoeana (Pilsbry, 1889) is synonymised with D. nigerrima (Gmelin, 1791). We find that morphologically cryptic species are not necessarily close genetically.     

Phylogenetic analysis of anostracans (Branchiopoda: Anostraca) inferred from nuclear 18S ribosomal DNA (18S rDNA) sequences

The nuclear small subunit ribosomal DNA (18S rDNA) of 27 anostracans (Branchiopoda: Anostraca) belonging to 14 genera and eight out of nine traditionally recognized families has been sequenced and used for phylogenetic analysis. The 18S rDNA phylogeny shows that the anostracans are monophyletic. The taxa under examination form two clades of subordinal level and eight clades of family level. Two families the Polyartemiidae and Linderiellidae are suppressed and merged with the Chirocephalidae, of which together they form a subfamily. In contrast, the Parartemiinae are removed from the Branchipodidae, raised to family level (Parartemiidae) and cluster as a sister group to the Artemiidae in a clade defined here as the Artemiina (new suborder). A number of morphological traits support this new suborder. The Branchipodidae are separated into two families, the Branchipodidae and Tanymastigidae (new family). The relationship between Dendrocephalus and Thamnocephalus requires further study and needs the addition of Branchinella sequences to decide whether the Thamnocephalidae are monophyletic. Surprisingly, Polyartemiella hazeni and Polyartemia forcipata ("Family" Polyartemiidae), with 17 and 19 thoracic segments and pairs of trunk limb as opposed to all other anostracans with only 11 pairs, do not cluster but are separated by Linderiella santarosae ("Family" Linderiellidae), which has 11 pairs of trunk limbs. All appear to be part of the Chirocephalidae and share one morphological character: double pre-epipodites on at least part of their legs. That Linderiella is part of the Polyartemiinae suggests that multiplication of the number of limbs occurred once, but was lost again in Linderiella. Within Chirocephalidae, we found two further clades, the Eubranchipus-Pristicephalus clade and the Chirocephalus clade. Pristicephalus is reinstated as a genus.     

Phylogenetic relationships among cirrate octopods (Mollusca: Cephalopoda) resolved using mitochondrial 16S ribosomal DNA sequences

PHYLOGENETIC RELATIONSHIPS AMONG THE CIRRATE OCTOPODS (MOLLUSCA: Cephalopoda) were investigated using partial sequences of the 16S rRNA mitochondrial gene. The derived phylogeny supports the traditional separation of cirrate families based on web form. Genera with a single web (Opisthoteuthis, Grimpoteuthis, Luteuthis, and Cirroctopus) are clearly distinct from those with an intermediate or secondary web (Cirroteuthis, Cirrothauma, and Stauroteuthis). The cirrates with a single web are separated into three groups. The first group is represented by Opisthoteuthis species, the second by Grimpoteuthis and Luteuthis, and the third by members of the genus Cirroctopus. There is no support for the isolation of Luteuthis in a separate family (Luteuthidae). There is, however, evidence of two groupings within the genus Opisthoteuthis. The data suggest the following revisions in the systematic classification of the cirrates: (1) Cirrothauma, Cirroteuthis, and Stauroteuthis be united in the Cirroteuthidae; (2) Grimpoteuthis and Luteuthis be placed in the Grimpoteuthidae; (3) Opisthoteuthis in the Opisthoteuthidae, and; (4) Cirroctopus be considered sufficiently distinct from both Opisthoteuthidae and Grimpoteuthidae to warrant placement in a new family.     

New insights into polychaete phylogeny (Annelida) inferred from 18S rDNA sequences

Annelid systematics and the ingroup relationships of polychaete annelids are matter of ongoing debates in recent analyses. For the investigation of sedentary polychaete relationships a molecular phylogenetic analysis was conducted based on 94 sequences of 18S rDNA, including unpublished sequences of 13 polychaete species. The data set was analyzed with maximum parsimony and maximum likelihood methods, as wells as Bayesian inference. As in previous molecular analyses the monophyly of many traditional polychaete families is confirmed. No evidence has been found for a possible monophyly of Canalipalpata or Scolecida. In all analyses a placement of the Echiura as a derived polychaete ingroup with a close relationship to the Capitellidae is confirmed. The orbiniids appear paraphyletic with regard to Questa. Travisia is transferred from Opheliidae to Scalibregmatidae. The remaining opheliids include a yet undescribed ctenodrilid species from Elba, whereas the other investigated ctenodrilid Ctenodrilus serratus groups with the Cirratulidae and shows a close affinity to the cirratulid genus Dodecaceria. A common ancestry of Branchiomaldane and Arenicola, which has been predicted on morphological data, is confirmed by the analysis and a sistergroup relationship between Arenicolidae and Maldanidae is also recovered. These results support our assumption that on the basis of a broader taxon sampling the phylogenetic position of controversially discussed taxa can be inferred by using 18S rDNA sequence data.     

Towards a phylogeny and evolution of Acochlidia (Mollusca: Gastropoda: Opisthobranchia)

The Acochlidia are unique among opisthobranch gastropods in combining extremely high morphological and ecological diversity with modest species diversity. The phylogeny of acochlidians has never been addressed by cladistic means, as their evolution has remained unknown. This study gives a first overview on more than 150 biological and morphological characters that are potentially useful for phylogenetic analysis. Based on 107 characters, a parsimony analysis (PAUP) was performed for all 27 valid acochlidian species together with 11 (plus two) outgroup taxa. The resulting strict consensus tree shows a moderate overall resolution, with at least some bootstrap support for most resolved nodes. The Acochlidia are clearly monophyletic, and originate from an unresolved basal opisthobranch level. The Acochlidia split into the Hedylopsacea (Tantulum (Hedylopsis (Pseudunela (Strubellia (‘Acochlidium’, ‘Palliohedyle’))))) and Microhedylacea (Asperspina (Pontohedyle, ‘Parhedyle’, ‘Microhedyle’, (Ganitus, Paraganitus))). The formerly enigmatic Ganitidae, resembling sacoglossan opisthobranchs by having dagger‐like rachidian radular teeth, are likely to be highly derived microhedylids. The paraphyly of some of the traditionally recognized family level taxa induced a preliminary reclassification. From the phylogenetic hypothesis obtained, we conclude that the acochlidian ancestor was marine mesopsammic. The colonization of limnic systems occurred twice, independently: first in the Caribbean (with the development of the small interstitial Tantulum elegans), and second in the Indo‐Pacific, with a radiation of large‐sized benthic acochlidian species. The evolution of extraordinary reproductive features, such as hypodermic impregnation by a complex copulative aparatus in hedylopsaceans, cutaneous insemination via spermatophores in microhedylaceans, and gonochorism in Microhedylidae s.l. (including Ganitidae), is discussed. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 124–154.     

The Strepsiptera problem: phylogeny of the holometabolous insect orders inferred from 18S and 28S ribosomal DNA sequences and morphology

Phylogenetic relationships among the holometabolous insect orders were inferred from cladistic analysis of nucleotide sequences of 18S ribosomal DNA (rDNA) (85 exemplars) and 28S rDNA (52 exemplars) and morphological characters. Exemplar outgroup taxa were Collembola (1 sequence), Archaeognatha (1), Ephemerida (1), Odonata (2), Plecoptera (2), Blattodea (1), Mantodea (1), Dermaptera (1), Orthoptera (1), Phasmatodea (1), Embioptera (1), Psocoptera (1), Phthiraptera (1), Hemiptera (4), and Thysanoptera (1). Exemplar ingroup taxa were Coleoptera: Archostemata (1), Adephaga (2), and Polyphaga (7); Megaloptera (1); Raphidioptera (1); Neuroptera (sensu stricto = Planipennia): Mantispoidea (2), Hemerobioidea (2), and Myrmeleontoidea (2); Hymenoptera: Symphyta (4) and Apocrita (19); Trichoptera: Hydropsychoidea (1) and Limnephiloidea (2); Lepidoptera: Ditrysia (3); Siphonaptera: Pulicoidea (1) and Ceratophylloidea (2); Mecoptera: Meropeidae (1), Boreidae (1), Panorpidae (1), and Bittacidae (2); Diptera: Nematocera (1), Brachycera (2), and Cyclorrhapha (1); and Strepsiptera: Corioxenidae (1), Myrmecolacidae (1), Elenchidae (1), and Stylopidae (3). We analyzed approximately 1 kilobase of 18S rDNA, starting 398 nucleotides downstream of the 5' end, and approximately 400 bp of 28S rDNA in expansion segment D3. Multiple alignment of the 18S and 28S sequences resulted in 1,116 nucleotide positions with 24 insert regions and 398 positions with 14 insert regions, respectively. All Strepsiptera and Neuroptera have large insert regions in 18S and 28S. The secondary structure of 18S insert 23 is composed of long stems that are GC rich in the basal Strepsiptera and AT rich in the more derived Strepsiptera. A matrix of 176 morphological characters was analyzed for holometabolous orders. Incongruence length difference tests indicate that the 28S + morphological data sets are incongruent but that 28S + 18S, 18S + morphology, and 28S + 18S + morphology fail to reject the hypothesis of congruence. Phylogenetic trees were generated by parsimony analysis, and clade robustness was evaluated by branch length, Bremer support, percentage of extra steps required to force paraphyly, and sensitivity analysis using the following parameters: gap weights, morphological character weights, methods of data set combination, removal of key taxa, and alignment region. The following are monophyletic under most or all combinations of parameter values: Holometabola, Polyphaga, Megaloptera + Raphidioptera, Neuroptera, Hymenoptera, Trichoptera, Lepidoptera, Amphiesmenoptera (Trichoptera + Lepidoptera), Siphonaptera, Siphonaptera + Mecoptera, Strepsiptera, Diptera, and Strepsiptera + Diptera (Halteria). Antliophora (Mecoptera + Diptera + Siphonaptera + Strepsiptera), Mecopterida (Antliophora + Amphiesmenoptera), and Hymenoptera + Mecopterida are supported in the majority of total evidence analyses. Mecoptera may be paraphyletic because Boreus is often placed as sister group to the fleas; hence, Siphonaptera may be subordinate within Mecoptera. The 18S sequences for Priacma (Coleoptera: Archostemata), Colpocaccus (Coleoptera: Adephaga), Agulla (Raphidioptera), and Corydalus (Megaloptera) are nearly identical, and Neuropterida are monophyletic only when those two beetle sequences are removed from the analysis. Coleoptera are therefore paraphyletic under almost all combinations of parameter values. Halteria and Amphiesmenoptera have high Bremer support values and long branch lengths. The data do not support placement of Strepsiptera outside of Holometabola nor as sister group to Coleoptera. We reject the notion that the monophyly of Halteria is due to long branch attraction because Strepsiptera and Diptera do not have the longest branches and there is phylogenetic congruence between molecules, across the entire parameter space, and between morphological and molecular data.     

Molecular phylogeny of Scaphopoda (Mollusca) inferred from 18S rDNA sequences: support for a Scaphopoda–Cephalopoda clade

The phylogenetic relationships of the Scaphopoda, one of the 'lesser' molluscan classes, with the other conchiferan taxa are far from clear. They appear either as the sister-group to the Bivalvia (Diasoma concept) or to a Gastropoda–Cephalopoda clade or to the Cephalopoda alone (helcionellid concept). We compiled a 18S rDNA sequence dataset of 48 molluscan species containing 17 scaphopods to test these hypotheses and to address questions regarding high-level relationships with the Scaphopoda. Both parsimony and maximum likelihood trees show low branch support at the base of the Conchifera, except for the robust clade uniting Scaphopoda and Cephalopoda. This result is corroborated by spectral analysis and likelihood mapping. We also tested alternative topologies which scored significantly worse both in tree length and in likelihood. The 18S rDNA data thus reject the Diasoma in favour of a Scaphopoda–Cephalopoda clade as proposed in the helcionellid concept. When plotted on the molecular tree, the pivotal morphological characters associated with the burrowing life style of the Bivalvia and Scaphopoda, i.e. mantle/shell enclosure of the body and the burrowing foot with true pedal ganglia, appear convergent in these groups. In contrast, the prominent and tilted dorsoventral body axes, multiple cephalic tentacles and a ring-shaped muscle attachment on the shell are potential synapomorphies of Scaphopoda and Cephalopoda. Most of the higher taxa within the Scaphopoda are supported by the molecular data. However, there is no support for the families Dentaliidae and Gadilidae. The basal position of the Fustiariidae within the Dentaliida is confirmed.     

Filling a gap in the phylogeny of flatworms: relationships within the Rhabdocoela (Platyhelminthes), inferred from 18S ribosomal DNA sequences

The phylogeny of the Rhabdocoela, a species-rich taxon of free-living flatworms, is reconstructed based on complete 18S rDNA sequences. The analysis includes 62 rhabdocoels and 102 representatives of all major flatworm taxa. In total, 46 new sequences are used, 41 of them from rhabdocoel species, five from proseriates. Phylogenetic analysis was performed using maximum parsimony and Bayesian inference. Clade support was evaluated with parsimony jackknifing, Bremer support indices and Bayesian posterior probabilities. The resulting cladogram corroborates that the Rhabdocoela is monophyletic, but its sister group remains uncertain. The 'Dalyellioida' and the 'Typhloplanoida', both former rhabdocoel subtaxa, are polyphyletic. Within the Rhabdocoela the monophyletic Kalyptorhynchia, characterized by a muscular proboscis, forms the sister group of all other rhabdocoels. The Schizorhynchia is a monophyletic subtaxon of the Kalyptorhynchia, with the split proboscis as a synapomorphy. Except for the Dalyelliidae and the Typhloplanidae, both freshwater taxa, none of the 'families' previously included in the 'Typhloplanoida' and the 'Dalyellioida' appears to be monophyletic. As a result of this analysis, three existing and four new taxon names are formally defined following the rules of the Phylocode.     

Hemolymph ferritin and radula structure in the limpets Patelloida alticostata and Patella peronii (Mollusca: Gastropoda)

• 1.1. The mean concentration of total hemolymph iron was 3060μg/100 ml in Patella peronii and 2950μg/100 ml in Patelloida alticostata.
• 2.2. Ferritin was found to act as a major iron-binding protein in the hemolymph of both P. peronii and P. alticostata.
• 3.3. P. alticostata ferritin has a molecular weight of approximately 505,000, while that of P. peronii has a mol wt. of approximately 520,000.
• 4.4. The lateral radula teeth of both species are mineralized by deposits of silica (SiO₂) and iron in the form of goethite (α-FeOOH).
• 5.5. Hemolymph ferritin is suggested to act as a high capacity transport system to supply iron to the mineralizing front of the radula.

     

Phylogenetic relationships ofPolemoniaceae inferred from 18S ribosomal DNA sequences

Cladistic analyses of chloroplast DNA disagree with current classifications by placingPolemoniaceae near sympetalous families with two staminal whorls, includingFouquieriaceae andDiapensiaceae, rather than near sympetalous families with a single staminal whorl, such asHydrophyllaceae andConvolvulaceae. To explore further the affinities ofPolemoniaceae, we sequenced 18S ribosomal DNA for eight genera ofPolemoniaceae and 31 families representing a broadly definedAsteridae. The distribution of variation in these sequences suggest some sites are hypervariable and multiple hits at these sites have obscured much of the hierarchical structure present in the data. Nevertheless, parsimony, least-squares minimum evolution, and maximum likelihood methods all support a monophyleticPolemoniaceae that is placed nearFouquieriaceae, Diapensiaceae and related ericalean families.     

High-resolution phylogeny for Helianthus (Asteraceae) using the 18S-26S ribosomal DNA external transcribed spacer

The sunflower genus, Helianthus, is recognized widely for the cultivated sunflower H. annuus and scientifically as a model organism for studying diploid and polyploid hybrid speciation, introgression, and genetic architecture. A resolved phylogeny for the genus is essential for the advancement of these scientific areas. In the past, phylogenetic relationships of the perennial species and polyploid hybrids have been particularly difficult to resolve. Using the external transcribed spacer region of the nuclear 18S-26S rDNA region, we reveal for the first time a highly resolved gene tree for Helianthus. Phylogenetic analysis allowed the determination of a monophyletic annual H. sect. Helianthus, a two-lineage polyphyletic H. sect. Ciliares, and the monotypic H. sect. Agrestis, all of which were nested within a large perennial and polyphyletic H. sect. Divaricati. The distribution of perennial polyploids and known annual diploid hybrids on this phylogeny suggested multiple independent hybrid speciation events that gave rise to at least four polyploids and three diploid hybrids. Also provided by this phylogeny was evidence for homoploid hybrid speciation outside H. sect. Helianthus. Finally, previous hypotheses about the secondary chemistry in the genus were tested in a phylogenetic framework to obtain a better understanding of the evolution of these compounds in Helianthus.     

New insight into the phylogeny of Mesozoa: Evidence from the 18S and 28S rRNA genes

The phylogenetic relationships of two Mesozoa groups were studied by the comparative analysis of complete sequences of 18S and 28S rRNA. Two groups of Mesozoa were found to form a statistically supported clade in phylogenetic trees. The results of the analysis placed Mesozoa in the Spiralia group of Lophotrochozoa and showed the tendency of Mesozoa to converge with one of the Annelida groups.     

CR1 retroposons provide a new insight into the phylogeny of Phasianidae species (Aves: Galliformes)

Chicken repeat 1 (CR1) elements, a class of retroposons belonging to non-long-terminal repeats, have been recognized as powerful tools for phylogenetic studies. Here we examine the phylogenetic relationships of 11 Phasianidae species based on CR1 retroposons. Together with 19 loci reported previously, a total of 99 CR1 loci were identified from chicken genome and turkey BAC clone sequences. 75 insertion events were used to address the branching order of 11 species in Phasianidae. The topology of our tree suggests that: 1) Gallus gallus possessed a basal phylogenetic position within Phasianidae and was related to Bambusicola thoracica (BSP=100%); 2) After the split of G. gallus and B. thoracica, Arborophila rufipectus diverged from Phasianidae (BSP=100%). Nine unambiguous insertion events supported a phylogenetic position of A. rufipectus different to previous mitochondrial data suggesting a hybrid origin or an ancient introgression of A. rufipectus; and 3) 22 CR1 insertion events strongly supported the eight phasianids under investigation sharing a common ancestor. Our study has revisited the phylogenetic position of G. gallus and A. rufipectus and provided a new insight into the phylogeny of Phasianidae birds. It showed that a CR1-based methodology has a great potential to be informative within Phasianidae in resolving relationships of closely related species whose radiation and speciation have occurred very recently.     

Phylogenetic relationships of the Acanthocephala inferred from 18S ribosomal DNA sequences

Phylogenetic relationships within the Acanthocephala have remained unresolved. Past systematic efforts have focused on creating classifications with little consideration of phylogenetic methods. The Acanthocephala are currently divided into three major taxonomic groups: Archiacanthocephala, Palaeacanthocephala, and Eoacanthocephala. These groups are characterized by structural features in addition to the taxonomy and habitat of hosts parasitized. In this study the phylogenetic relationships of 11 acanthocephalan species are examined with 18S rDNA sequences. Maximum parsimony, minimum evolution, and maximum likelihood methods are used to estimate phylogenetic relationships. Within the context of sampled taxa, all phylogenetic analyses are consistent with monophyly of the major taxonomic groups of the Acanthocephala, suggesting that the current higher order classification is natural. The molecular phylogeny is used to examine patterns of character evolution for various structural and ecological characteristics of the Acanthocephala. Arthropod intermediate host distributions, when mapped on the phylogeny, are consistent with monophyletic groups of acanthocephalans. Vertebrate definitive host distributions among the Acanthocephala display independent radiations into similar hosts. Levels of uncorrected sequence divergence among acanthocephalans are high; however, relative-rate tests indicate significant departure from rate uniformity among acanthocephalans, arthropods, and vertebrates. This precludes comparison of 18S divergence levels to assess the relative age of the Acanthocephala. However, other evidence suggests an ancient origin of the acanthocephalan-arthropod parasitic association.     

Linnaeus' Neptunea (Mollusca: Gastropoda)

Three species of the arcto-boreal, large gastropod Neptunea , described by Linnaeus in 1758 and 1771, occur in large numbers over wide areas of the inshore North Atlantic and adjacent Arctic seas and are conspicuous among Pliocene and Pleistocene molluscs in the Icelandic, North Sea, and western Mediterranean basins. Selections of lectotypes for these species from shells in the collection of the Linnean Society of London, and designations of their type localities, establish the identity of Linnaeus' neptunes and more accurately determine their geographic and geologic distribution. The geographic range of Neptunea (Neptunea) antiqua (L.), the type species, now extends from southern Norway to the northern Biscay coast of France and from the westernmost Baltic Sea to southwestern Ireland; this species also occurs in Pliocene-Holocene marine deposits in West and East Germany, Sweden, the Netherlands, England and France. Its type locality is determined to be the North Sea. N. (Neptunea) despecta (L.) lives in the eastern Canadian Arctic, off southern Greenland, the Barents Sea, and North Atlantic as far south as Massachusetts and Portugal; it also occurs in Pliocene-Holocene strata of eastern Canada, east-central Greenland, Norway (including Svalbard), the Soviet Union, Sweden and England. Its type locality is determined to be the postglacial deposits at Uddevalla in southwestern Sweden. N. (Sulcosipho) contraria (L.) now extends from the southern Biscay coast of France to Cape Spartel, Morocco; this species also occurs in Pleistocene and lower Holocene sequences of the western Mediterranean. Its type locality is determined to be Vigo Bay, Spain. A closely related fossil species, N. (S.) angulata (S. V. Wood), occurs in Pliocene and Pleistocene deposits of the North Sea basin.