Uppermost Pliensbachian-Lowermost Toarcian ostracod assemblages from the Western Tethys: Comparison between Traras Mountains (Algeria), Subbetic (Spain), and Algarve (Portugal)

Major changes in ostracod assemblages have been recorded in the Lower Jurassic of Western Tethys related to biotic crises of the Pliensbachian-Toarcian boundary and the Polymorphum-Levisoni boundary (Toarcian Oceanic Anoxic Event). The study is focused on the ostracods assemblages from Benzerka section (Traras Mountains, Algeria) and their comparison with sections from External Subbetic and Algarve Basin (South Iberian Palaeomargin). Three stratigraphic intervals coincident with the ammonite zones have been differentiated with important fluctuations in the composition of ostracod assemblages. In the ostracod assemblages from the Traras Mountains the turnover related to this benthic biotic crisis is shown by assemblages previous to the biotic crisis (uppermost Pliensbachian) mainly composed by families Healdiidae and Cytherellidae to assemblages just after the T-OAE (upper part of the Levisoni Zone) with assemblages dominated by families Protocytheridae and Polycopidae and the extinction of family Healdiidae (suborder Metacopina). The Toarcian Oceanic Anoxic Event (T-OAE) probably resulted in restricted conditions but a barren interval due to oxygen-depleted conditions in this setting is not recorded. In this context, the change of components of ostracod assemblages looks gradual. In the Southiberian Palaeomargin, represented by the External Subbetic the turnover of ostracods assemblages is also recorded but the families involved are different than in Traras Mountains. Therefore, different phases have been differentiated in the ostracod turnover occurring from Upper Pliensbachian (assemblages dominated by families Pontocyprididae, Healdiidae and Bairdiidae) to end of Lower Toarcian (assemblages dominated by family Cytherellidae and the extinction of family Healdiidae). In the Algarve Basin the families Healdiidae and Bairdiidae were dominant previously to the Toarcian Oceanic Anoxic Event. Differences in the composition of ostracod assemblages between Traras Mountains and External Subbetic may be related to the fragmentation of these palaeomargins related to early stages of rifting in the Western Tethys. Moreover, the incidence of oxygen-depleted conditions was higher in External Subbetic than in Traras Mountains where some ostracod genera survive during the biotic crisis.     

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 of xenodontine snakes inferred from 12S and 16S ribosomal RNA sequences

The phylogenetic relationships of xenodontine snakes are inferred from sequence analyses of portions of two mitochondrial genes (12S and 16S ribosomal RNA) in 85 species. Although support values for most of the basal nodes are low, the general pattern of cladogenesis observed is congruent with many independent molecular, morphological, and geographical data. The monophyly of xenodontines and the basal position of North American xenodontines in comparison with Neotropical xenodontines are favored, suggesting an Asian-North American origin of xenodontines. West Indian xenodontines (including endemic genera and members of the genus Alsophis) appear to form a monophyletic group belonging to the South American clade. Their mid-Cenozoic origin by dispersal using ocean currents is supported. Within South American mainland xenodontines, the tribes Hydropsini, Pseudoboini, and Xenodontini are monophyletic. Finally, our results suggest that some morphological and ecological traits concerning maxillary dentition, macrohabitat use, and foraging strategy have appeared multiple times during the evolution of xenodontine snakes.     

Phylogeny of Myrmeleontiformia based on larval morphology (Neuropterida: Neuroptera)

The suborder Myrmeleontiformia is a derived lineage of lacewings (Insecta: Neuroptera) including the families Psychopsidae, Nemopteridae, Nymphidae, Ascalaphidae and Myrmeleontidae. In particular, Myrmeleontidae (antlions) are the most diverse neuropteran family, representing a conspicuous component of the insect fauna of xeric environments. We present the first detailed quantitative phylogenetic analysis of Myrmeleontiformia, based on 107 larval morphological and behavioural characters for 36 genera whose larvae are known (including at least one representative of all the subfamilies of the suborder). Four related families were used as outgroups to polarize character states. Phylogenetic analyses were conducted using both parsimony and Bayesian methods. The reconstructions resulting from our analyses corroborate the monophyly of Myrmeleontiformia. Within this clade, Psychopsidae are recovered as the sister family to all the remaining taxa. Nemopteridae (including both subfamilies Nemopterinae and Crocinae) are recovered as monophyletic and sister to the clade comprising Nymphidae + (Myrmeleontidae + Ascalaphidae). Nymphidae consist of two well‐supported clades corresponding to the subfamilies Nymphinae and Myiodactylinae. Our results suggest that Ascalaphidae may not be monophyletic, as they collapse into an unresolved polytomy under the Bayesian analysis. In addition, the recovered phylogenetic relationships diverge from the traditional classification scheme for ascalaphids. Myrmeleontidae are reconstructed as monophyletic, with the subfamilies Stilbopteryginae, Palparinae and Myrmeleontinae. We retrieved a strongly supported clade comprising taxa with a fossorial habit of the preimaginal instars, which represents a major antlion radiation, also including the monophyletic pit‐trap building species.     

Multivariate hierarchical analyses of Early Jurassic Ostracoda assemblages

Palaeobiogeographic patterns of Early Jurassic ostracods from the northern and southern hemispheres (96 sections located in Europe, North Africa, Western Australia and North and South America) based on 243 species-level records document global patterns of distribution that can be compared to those previously published on ostracods from the European Epicontinental Sea and Tethyan and South Panthalassa areas. All described records of ostracods from both hemispheres spanning the Hettangian to Early Toarcian have been compiled and verified, and their patterns of origin and distribution have been interpreted. Jaccard coefficient of similarity was used to asses similarities among European, American and Tethyan ostracod shelf faunas. The numerical analysis shows a progressive longitudinal gradient in provincialism through the Early Jurassic, consistent with the northward drift of Tethyan ostracod faunas towards the European Epicontinental Sea and the southward movement of European taxa into Tethys and Panthalassa oceans. The spread of cosmopolitan species and extinction of endemic species, allied to the disappearance of geographical barriers, warmer climate conditions and rising sea levels can explain the reduction in ostracod diversity and the east-west provincialism throughout the Early Jurassic. Interchange between hemispheres, including bipolar distributions, are recognized from the Sinemurian time, pointing out that for most of the studied period, the climate worldwide was warm and tropical.     

The evolutionary pathway of light emission in myodocopid Ostracoda

The evolutionary history of bioluminescence and iridescence in myodocopid ostracods was estimated by phylogenetic analysis of mitochondrial 16S ribosomal RNA sequences. The inferred phylogeny of the myodocopids suggests that the common ancestor of Myodocopida evaluated in this study exhibits iridescence. This type of light emission was once lost and recaptured independently in the descendant lineages. Bioluminescent species also evolved from non-luminous ancestral species. In the suborder Myodocopina, all the bioluminescent species form a monophyletic group, suggesting that bioluminescence evolved only once. Structural differences between two bioluminescent groups in the order Myodocopida suggests independent origins for bioluminescence.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 449–455.     

Molecular phylogeny and biogeography of the endemic Hawaiian Succineidae (Gastropoda: Pulmonata)

The endemic Hawaiian Succineidae represent an important component of the exceptionally diverse land snail fauna of the Hawaiian Islands, yet they remain largely unstudied. We employed 663-bp fragments of the cytochrome oxidase I (COI) mitochondrial gene to investigate the evolution and biogeography of 13 Hawaiian succineid land snail species, six succineid species from other Pacific islands and Japan, and various outgroup taxa. Results suggest that: (1) species from the island of Hawaii are paraphyletic with species from Tahiti, and this clade may have had a Japanese (or eastern Asian) origin; (2) species from five of the remaining main Hawaiian islands form a monophyletic group, and the progression rule, which states that species from older islands are basal to those from younger islands, is partially supported; no geographic origin could be inferred for this clade; (3) succineids from Samoa are basal to all other succineids sampled (maximum likelihood) or unresolved with respect to the other succineid clades (maximum parsimony); (4) the genera Succinea and Catinella are polyphyletic. These results, while preliminary, represent the first attempt to reconstruct the phylogenetic pattern for this important component of the endemic Hawaiian fauna.     

竹亚科系统学和生物地理学研究进展及存在的问题

对近年来在竹亚科作为一个单系类群的界定、其系统位置的确定、内部系统演化趋势以及地理分布和起源方面研究所取得的进展进行了评述。竹亚科作为一个单系类群仅包括了木本的竹族（Bambuseae)和一个草本的莪利竹族（Olyreae),其中莪利竹族分布在新几内亚的伊里安竹（Buergersiochloa)处于Olyreae最基部。禾本科12个亚科中除了3个亚科为基部类群以外,其余9个亚科分成PACCAD（包括黍亚科,狭义的芦竹亚科,广义的虎尾草亚科,假淡竹叶亚科,三芒草亚科和扁芒草亚科）和BOP单系分支（包括竹亚科,稻亚科和早熟禾亚科）。在BOP支中,竹亚科与早熟禾亚科相近缘,共同组成稻亚科的姐妹群。竹亚科分成草本和木本两个单系类群,木本竹子又分成热带和温带支系,热带支系进一步分成新世界热带和旧世界热带两个单系类群。从现有的化石证据和基部类群的地理分布推断,竹亚科很可能起源于晚白垩纪的冈瓦纳古陆。最后,本文就竹亚科研究尚存在的问题做了初步探讨。     

A phylogeny of Packera (Senecioneae; asteraceae) based on internal transcribed spacer region sequence data and a broad sampling of outgroups

A phylogeny of Packera is presented based on sequence data from the internal transcribed spacer region of nuclear ribosomal DNA of 26 species (28 populations) of Packera and 23 outgroup taxa, including representatives of all three subtribes of the Senecioneae. The results support a Mexican origin for Packera, with its closest relatives found among Old World taxa in the subtribe Senecioninae, such as Senecio jacobaea and Pericallis. Packera species from the west coast of the United States, previously included in the section Bolanderi of Greenman, are part of a basal assemblage including species of Greenman's Mexican section Sanguisorboidei. The rest of Packera separates into two sister groups, one containing species from the Arizona-New Mexico region and the other containing more geographically diverse taxa. Among the outgroups, New World Senecio species are monophyletic and two Tussilaginoid assemblages are strongly supported; the Tephroseroid group (Tephroseris and Sinosenecio) plus Petasites combine with the Luina complex to form a clade of north temperate taxa, and the four Mexican genera (Psacalium, Robinsonecio, Barkleyanthus, and Pittocaulon) form a monophyletic group.     

A new genus of phreatoicidean isopod (Crustacea) from the north Kimberley region, Western Australia

A new genus and species of phreatoicidean isopod, Crenisopus acinifer, has been collected from a freshwater spring in the northern Kimberley region of Western Australia. Empirical cladistic analysis of 10 exemplars of phreatoicidean genera found a single cladogram. The new genus and species assumed a basal position in the Phreatoicidea, placing it within the family Amphisopodidae sensu lata. This family, however, was not monophyletic in the preliminary cladogram, suggesting that the taxonomic structure of the suborder must be revised. The cladogram provided evidence for the monophyly of the Phreatoicidae and its New Zealand clade. The analysis suggested that clades of modern phreatoicideans diverged from one another during the Mesozoic Era after they entered fresh water, but prior to the fragmentation of East Gondwana.     

Relationships of extant lower Brachycera (Diptera): a quantitative synthesis of morphological characters

With over 80 000 described species, Brachycera represent one of the most diverse clades of organisms with a Mesozoic origin. Larvae of the majority of early lineages are detritivores or carnivores. However, Brachycera are ecologically innovative and they now employ a diverse range of feeding strategies. Brachyceran relationships have been the subject of numerous qualitative analyses using morphological characters. These analyses are often based on characters from one or a few character systems and general agreement on relationships has been elusive. In order to understand the evolution of basal brachyceran lineages, 101 discrete morphological characters were scored and compiled into a single data set. Terminals were scored at the family level, and the data set includes characters from larvae, pupae and adults, internal and external morphology, and male and female terminalia. The results show that all infraorders of Brachycera are monophyletic, but there is little evidence for relationships between the infraorders. Stratiomyomorpha, Tabanomorpha, and Xylophagomorpha together form the sister group to Muscomorpha. Xylophagomorpha and Tabanomorpha are sister groups. Within Muscomorpha, the paraphyletic Nemestrinoidea form the two most basal lineages. There is weak evidence for the monophyly of Asiloidea, and Hilarimorphidae appear to be more closely related to Eremoneura than other muscomorphs. Apsilocephalidae, Scenopinidae and Therevidae form a clade of Asiloidea. This phylogenetic evidence is consistent with the contemporaneous differentiation of the main brachyceran lineages in the early Jurassic. The first major radiation of Muscomorpha were asiloids and they may have diversified in response to the radiation of angiosperms in the early Cretaceous.     

PHYLOGENETIC ANALYSES OF THE BRYOPSIDALES (ULVOPHYCEAE,CHLOROPHYTA) BASED ON RUBISCO LARGE SUBUNIT GENE SEQUENCES1

Current taxonomy of the Bryopsidales recognizes eight families; most of which are further categorized into two suborders, the Bryopsidineae and Halimedineae. This concept was supported by early molecular phylogenetic analyses based on rRNA sequence data, but subsequent cladistic analyses of morphological characters inferred monophyly in only the Halimedineae. These conflicting results prompted the current analysis of 32 taxa from this diverse group of green algae based on plastid‐encoded RUBISCO large subunit (rbcL) gene sequences. Results of these analyses suggested that the Halimedineae and Bryopsidineae are distinct monophyletic lineages. The families Bryopsidaceae, Caulerpaceae, Codiaceae, Derbesiaceae, and Halimediaceae were inferred as monophyletic, however the Udoteaceae was inferred as non‐monophyletic. The phylogenetic position of two taxa with uncertain subordinal affinity, Dichotomosiphon tuberosus Lawson and Pseudocodium floridanum Dawes & Mathieson, were also inferred. Pseudocodium was consistently placed within the halimedinean clade suggesting its inclusion into this suborder, however familial affinity was not resolved. D. tuberosus was the inferred sister taxon of the Halimedineae based on analyses of rbcL sequence data and thus a possible member of this suborder.     

A molecular phylogeny of heterodont bivalves (Mollusca: Bivalvia: Heterodonta): new analyses of 18S and 28S rRNA genes

A new molecular phylogeny is presented for the highly diverse, bivalve molluscan subclass Heterodonta. The study, the most comprehensive for heterodonts to date, used new sequences of 18S and 28S rRNA genes for 103 species from 49 family groups with species of Palaeoheterodonta (Trigoniidae, Margaritiferidae and Unionidae) as outgroups. Results confirm previous analyses that the Carditidae/Astartidae/Crassatellidae clade is basal to all other heterodonts including Anomalodesmata (often classified as a separate subclass or order). Thyasiroidea occupy a near basal position between the Crassatelloidea and Anomalodesmata. Lucinidae form a well‐supported monophyletic group distinct from Thyasiridae and Ungulinidae. The Solenoidea and Hiatelloidea link as sister groups distant from the Tellinoidea and Myoidea, respectively, where they had been previously associated. The position of the Gastrochaenidae is unstable but does not group with myoidean taxa. Species of four families of Galeommatoidea form a clade that also includes Sportellidae of the Cyamioidea. The Cardioidea and Tellinoidea form highly supported, long branched, individual clades but group as sister taxa. A major clade including Veneroidea, Mactroidea, Myoidea and other families is given the unranked name Neoheterodontei. There is no support for a separate order Myoida (Myoidea and Pholadoidea). Dreissenidae group within the clade including Myidae, Corbulidae, Pholadidae and Teredinidae. The Corbiculoidea is confirmed as polyphyletic with the Sphaeriidae and Corbiculidae forming separate clades within the Neoheterodontei; Corbiculidae grouping with the Glauconomidae. Hemidonacidae are unrelated to the Cardiidae, as previously proposed, but nest within the Neoheterodontei. The Gaimardiidae group near to the Ungulinidae and not with Cyamioidea where most recently classified. The family Ungulinidae, previously classified in the Lucinoidea, forms a well‐supported clade within the Neoheterodontei and is elevated to superfamily rank — Ungulinoidea. The monophyletic status of Glossoidea, Arcticoidea and Veneroidea is unconfirmed. A brief review of the fossil record of the heterodonts indicates that the basal clades of Crassatelloidea, Anomalodesmata and Lucinoidea diverged very early in the Lower Palaeozoic. Other groups such as the Hiatelloidea, Solenoidea, Gastrochaenidae probably were of late Palaeozoic origins. The Cardioidea and Tellinoidea originated in the Triassic while major groups of Neoheterodontei radiated in the Late Mesozoic. The phylogenetic position of the Thyasiroidea and Galeommatoidea suggests a longer fossil history than has so far been recognized.     

Phylogeny and infrageneric classification of Symplocos (Symplocaceae) inferred from DNA sequence data

Symplocos comprises ～300 species of woody flowering plants with a disjunct distribution between the warm-temperate to tropical regions of eastern Asia and the Americas. Phylogenetic analyses of 111 species of Symplocos based on the nuclear ribosomal internal transcribed spacer (ITS) region and the chloroplast genes rpl16, matK, and trnL-trnF yielded topologies in which only one of the four traditionally recognized subgenera (Epigenia; Neotropics) is monophyletic. Section Cordyloblaste (subgenus Symplocos; eastern Asia) is monophyletic and sister to a group comprising all other samples of Symplocos. Section Palura (subgenus Hopea; eastern Asia) is sister to a group comprising all other samples of Symplocos except those of section Cordyloblaste. Symplocos wikstroemiifolia (eastern Asia) and S. tinctoria (southeastern United States), both of subgenus Hopea, form a clade that groups with S. longipes (tropical North America) and the species of subgenus Epigenia. The remaining samples of subgenus Hopea (eastern Asia) form a clade. Section Neosymplocos (subgenus Microsymplocos; Neotropics) is well nested within a clade otherwise comprising the samples of section Symplocastrum (subgenus Symplocos; Neotropics). Section Urbaniocharis (subgenus Microsymplocos; Antilles) groups as sister to the clade comprising Symplocastrum and Neosymplocos. The data support the independent evolution of deciduousness among section Palura and S. tinctoria. The early initial divergence of sections Cordyloblaste and Palura from the main group warrants their recognition at taxonomic levels higher than those at which they are currently placed. An inferred eastern Asian origin for Symplocos with subsequent dispersal to the Americas is consistent with patterns from other phylogenetic studies of eastern Asian-American disjunct plant groups but contrary to a North American origin inferred from the earliest fossil occurrences of the genus.     

Ostracods had colonized estuaries by the late Silurian

The fossil record of terrestrialization documents notable shifts in the environmental and physiological tolerances of many animal and plant groups. However, for certain significant components of modern freshwater and terrestrial environments, the transition out of marine settings remains largely unconstrained. Ostracod crustaceans occupy an exceptional range of modern aquatic environments and are invaluable palaeoenvironmental indicators in the fossil record. However, pre-Carboniferous records of supposed non-marine and marginal marine ostracods are sparse, and the timing of their marine to non-marine transition has proven elusive. Here, we reassess the early environmental history of ostracods in light of new assemblages from the late Silurian of Vietnam. Two, low diversity but distinct ostracod assemblages are associated with estuarine deposits. This occurrence is consistent with previous incidental reports of ostracods occupying marginal and brackish settings through the late Silurian and Devonian. Therefore, ostracods were pioneering the occupation of marginal marine and estuarine settings 60 Myr before the Carboniferous and they were a component of the early phase of transition from marine to non-marine environments.     

Ecdysozoa: The Relationship between Cycloneuralia and Panarthropoda

The hypothesis that molting protostomes such as nematodes and arthropods form a monophyletic group known as Ecdysozoa is directly opposed to Articulata, in which some segmented protostomes such as annelids and arthropods form a monophyletic taxon. Ultrastructural and cladistic studies have led to the widely accepted hypothesis that nematodes belong among the protostomes. While early molecular studies suggested that nematodes were basal triploblasts, more recent molecular evidence suggests that this was an artifact of ‘long branch attraction’ and 18S rRNA gene, total evidence and hox gene studies all support the placement of nematodes within Ecdysozoa. The branching pattern within Ecdysozoa has been difficult to elucidate, but it now appears that priapulids and kinorhynchs form the earliest branching clade, followed by nematodes + nematomorphs, and finally the panarthropods. This suggests that Cycloneuralia is paraphyletic and that arthropods are the most derived of the ecdysozoans.     

甘肃玉门下沟地区早白垩世下沟组介形类

甘肃玉门下沟地区下沟组介形类化石十分丰富,该地区下沟组介形类化石共计9属4亚属,21种,本文描述了其中4新种,即Cypridea(Cyamocypris)xiagouensissp.nov.,Cypridea(Cypridea)subunicostatasp.nov.,Stenestroemiasubpeculiarissp.nov.和Stenestroemiaxiagouensissp.nov.。该介形类化石组合尤以Cypridea最为繁盛,通过分析介形类属种的形态特征和化石组合特征并结合岩性特征,推断下沟组的地质时代为早白垩世巴列姆期;并认为下沟组为水动力较弱的淡水-微咸水河湖相沉积。     

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.     

PHYLOGENY OF THE ULVOPHYCEAE (CHLOROPHYTA): CLADISTIC ANALYSIS OF NUCLEAR-ENCODED rRNA SEQUENCE DATA1

Cladistic analysis of nuclear-encoded rRNA sequence data provided us with the basis for some new hypotheses of relationships within the green algal class Ulvophyceae. The orders Ulotrichales and Ulvales are separated from the clade formed by the remaining orders of siphonous and siphonocladous Ulvophyceae (Caulerpales, Siphonocladales /Cladophorales [S/C] complex, and the Dasycladales), by the Chlorophyceae and Pleurastrophyceae. Our results suggest that the Ulvophyceae is not a monophyletic group. Examination of inter- and intra-ordinal relationships within the siphonous and siphonocladous ulvophycean algae revealed that Cladophora, Chaetomorpha, Anadyomene, Microdictyon, Cladophoropsis and Dictyosphaeria form a clade. Thus the hypothesis, based on ultrastructural features, that the Siphonocladales and Cladophorales are closely related is supported. Also, the Caulerpales is a monophyletic group with two lineages; Caulerpa, Halimeda, and Udotea comprise one, and Bryopsis and Codium comprise the other. The Dasycladales (Cymopolia and Batophora) also forms a clade, but this clade is not inferred to be the sister group to the S/C complex as has been proposed. Instead, it is either the sister taxon to the Caulerpales or basal to the Caulerpales and S/C clade The Trentepohliales is also included at the base of the siphonous and siphonocladous ulvophycean clade. The Pleurastrophyceae, which, like the Ulvophyceae, posses a counter-clockwise arrangement of flagellar basal bodies, are more closely related to the Chlorophyceae than to the Ulvophyceae based on rRNA sequences. Thus, the arrangement of basal bodies does not diagnose a monophyletic group. Previously reported hypotheses of phylogenetic relationships of ulvophycean algae were tested. In each case, additional evolutionary steps were required to obtain the proposed relationships. Relationships of ulvophycean algae to other classes of green algae are discussed.     

93 Progress in characterizing the symbiodinium sp. in soritid foraminifera

Our research seeks to clarify the phylogeny of the Caulerpales through analyses of rbcL (large subunit of ribulose 1,5 biphosphate carboxylase/oxygenase) gene sequences. In a review of caulerpalean taxonomy, Hillis-Colinvaux (1984) recognized two suborders (Bryopsidineae and Halimedineae) on the basis of anatomical, physiological, and habitat characteristics. The Bryopsidineae (including the genera Bryopsis, Derbesia , and Codium ) have cosmopolitan distributions, non-holocarpic reproduction, and homoplasty, while the Halimedineae (including Caulerpa, Halimeda, and Udotea) have tropical to subtropical distributions, holocarpic reproduction, and heteroplasty. Previous phylogenetic analyses based on 18S rRNA sequence data supported the hypothesis of two monophyletic suborders within the Caulerpales (Zechman et al 1990). However, cladistic analyses of morphological characters (Vroom 1998) suggested that only the Halimedineae was monophyletic. Preliminary maximum likelihood and Bayesian analyses suggest the Halimedineae and Bryopsidineae form separate monophyletic groups, with robust support (bootstrap and posterior probabilities) for the former and moderate to poor support for the latter. The families of the Halimedineae (Caulerpaceae, Udoteaceae) form monophyletic sister groups with robust support. The freshwater family Dichotomosiphonaceae was inferred to be basal to the marine Halimedineae clade. The families within the Bryopsidineae (Derbesiaceae, Bryopsidaceae, Codiaceae) each form distinct monophyletic groups. The Codiaceae forms a basal monophyletic group to the sister clade of Bryopsidaceae and Derbeseaceae. This research was partially supported from a NSF grant (DEB-0128977 to FWZ).