AN ATLANTIC POPULATION OF PIKEA CALIFORNICA (DUMONTIACEAE,RHODOPHYTA)1

The marine red alga Pikea californica Harvey, previously known only from the east coast of Japan and the west coast of North America, was found in 1983 to be abundant in the surge zone throughout the Isles of Scilly archipelago, off SW England. Examination of herbarium material showed that the population was present in 1967. All plants observed in July 1983 and September 1984 were sterile, but reproductive male and female plants were collected in November 1983. The habitat and phenology of P. californica in the Isles of Scilly closely resemble those of Paczfic populations. English plants are vegetatively and reproductively identical to the type and other California specimens. They can easily be distinguished from Sphaerococcus coronopifolius Stackhouse (Sphaerococcaceae, Gigartinales), the most similar species in the flora of the British Isles, by the presence in transverse section of several lacunae, representing axial and whorlbranchletjilaments, in contrast to the single axial filament of S. coronopifolius. It is possible that the Isles of Scilly population of P. californica is a relict of a species once more widespread, but it seems more likely that it is another example of the well-established pattern of marine introductions into the British Isles from the North Paczfic. The range of temperature regimes occupied by P. californica in the Pacific suggests that the species could become more widespread in Europe, but at present it appears to be confined to the Isles of Scilly.     

The effects of sulphur dioxide pollution on bark epiphytes

Abstract

Sematophyllum substrumulosum (Hampe) Broth. was found in 1995 on a decaying trunk of Pinus in Tresco, Isles of Scilly, the first report of the species in the British Isles.     

African Hepatics

Abstract

Lophocolea bispinosa, new to the British Isles, is described in detail. This small dioecious species, which may have been introduced from New Zealand, is well established in the Isles of Scilly, especially in and around the Abbey Gardens in Tresco.     

Underwater observations on the vertical distribution of algae at St Mary's,Isles of Scilly

The vertical distribution of benthic marine algae on a sublittoral cliff in the Isles of Scilly is described and briefly compared with that found in other parts of the British Isles.     

The distribution and reproduction of Pterosiphonia complanata

The geographical distribution of the red alga Pterosiphonia complanata (Clem.) Falkenb. is described. New records confirm that it is restricted to the warmer waters of the North Atlantic and extend its known distribution in the British Isles where it is at the northern limits of its range. The apparent scarcity and restricted distribution of the species in the British Isles and the absence of sexual plants throughout its range are discussed in relation to the habitat and possible life history of the species.     

SYSTEMATICS AND PHYLOGEOGRAPHY OF THE INVASIVE RED ALGA, POLYSIPHONIA HARVEYI

Polysiphonia harveyi Bailey was first described from Connecticut in 1848 and morphologically similar species, such as P. japonica and P. strictissima , have subsequently been described many times from different localities such as Japan and New Zealand, placing the taxonomy and nomenclature of this morphologically variable species in confusion. Polysiphonia harveyi is regarded as an alien in the British Isles and the north-eastern North Atlantic and is reported to be spreading rapidly. The first confirmed collection of P. harveyi from the British Isles was in 1908; the source of the British introduction remains unknown. In conjunction with breeding data, rbc L sequences for samples of P. harveyi , P. strictissima , P. japonica and P. akkeshiensis collected from New Zealand, Atlantic and Pacific North America, Japan and Europe, reveal that P. harveyi, P. japonica and P. akkeshiensis constitute a single biological species. The correct name for this is P. harveyi , whilst P. strictissima from New Zealand is a sibling species, distinct from P. harveyi. The center of genetic diversity of P. harveyi is in Japan. The original source of the introduced P. harveyi in the British Isles, Europe and Nova Scotia appears to be Hokkaido, Japan. Separate introductions from a single source population into New Zealand and Pacific and Atlantic North America from Honshu, Japan, apparently have occurred.     

Paramoeba: A Common Marine Genus

Amoebae of the genus Paramoeba Schaudinn, 1896, have been found in British waters, further attesting to the wide distribution and common occurrence of these unusually interesting marine protozoa. The British strains belong to the species P. pemaquidensis Page, 1970, first described from the Atlantic coast of North America. The Nebenkörper appears to be characteristic of a morphologically and systematically homogeneous group of amoebae.     

Differential Parasitism of Native and Introduced Snails: Replacement of a Parasite Fauna

The role of parasites in a marine invasion was assessed by first examining regional patterns of trematode parasitism in the introduced Japanese mud snail, Batillaria cumingi (= B. attramentaria), in nearly all of its introduced range along the Pacific Coast of North America. Only one parasite species, which was itself a non-native species, Cercaria batillariae was recovered. Its prevalence ranged from 3 to 86%. Trematode diversity and prevalence in B. cumingi and a native sympatric mud snail, Cerithidea californica, were also compared in Bolinas Lagoon, California. Prevalence of larval trematodes infecting snails as first intermediate hosts was not significantly different (14% in B. cumingi vs 15% in C. californica). However, while the non-native snail was parasitized only by one introduced trematode species, the native snail was parasitized by 10 native trematode species. Furthermore, only the native, C. californica, was infected as a second intermediate host, by Acanthoparyphium spinulosum(78% prevalence). Given the high host specificity of trematodes for first intermediate hosts, in marshes where B. cumingi is competitively excluding C. californica, 10 or more native trematodes will also become locally extinct.     

A new xanthone-containing Micarea from Northwest Europe and the Pacific Northwest of North America

Abstract:Micarea xanthonica sp. nov. is described from the western British Isles, westernmost Norway and the Pacific Northwest of North America. It belongs to the M. prasina group, but differs from related species in possessing xanthones in the thallus.     

THE GENUS PIKEA (DUMONTIACEAE,RHODOPHYTA) IN ENGLAND AND THE NORTH PACIFIC: COMPARATIVE MORPHOLOGICAL,LIFE HISTORY,AND MOLECULAR STUDIES1

A Pikea species attributed to Pikea californica Harvey has been established in England since at least 1967. Previously, this species was believed to occur only in Japan and Pacific North America. Comparative morphological studies on field-collected material and cultured isolates from England, California, and Japan and analysis of organellar DNA restriction fragment length polymorphisms, detected using labeled organellar DNA as a non-radioactive probe, showed that English Pikea is conspecific with P. californica from California. Both populations consist of dioecious gametophytes with heteromorphic life histories involving crustose tetrasporophytes; 96% of organellar DNA bands were shared between interoceanic samples. A second dioecious species of Pikea, P. pinnata Setchell in Collins, Holden et Setchell, grows sympatrically with P. californica near San Francisco but can be distinguished by softer texture, more regular branching pattern, and elongate cystocarpic axes. Pikea pinnata and P. californica samples shared 49–50% of organellar DNA bands, consistent with their being distinct species. Herbarium specimens of P. robusta Abbott resemble P. pinnata in some morphological features but axes are much wider; P. robusta may represent a further, strictly sub-tidal species but fertile material is unknown. Pikea thalli from Japan, previously attributed to P. californica and described here as Pikea yoshizakii sp. nov., are monoecious and show a strikingly different type of life history. After fertilization, gonimoblast filaments grow outward through the cortex and form tetrasporangial nemathecia; released tetraspores develop directly into erect thalli. Tetrasporoblastic life histories are characteristic of certain members of the Phyllophoraceae but were previously unknown in the Dumontiaceae. Japanese P. yoshizakii shared 55 and 56% of organellar DNA bands with P. californica and P. pinnata, respectively; phylogenetic analysis indicated equally distant relationships to both species. Pikea yoshizakii or a closely similar species with the same life history occurs in southern California and Mexico.     

The recent geographical expansion of <Emphasis Type="Italic">Caprella californica</Emphasis> (Caprellidea: Caprellidae) around the coastline of Australia

The amphipod Caprella californica is native to California, but is known from the Pacific coast of North America, Mexico, Chile, Japan, Hong Kong and South Africa. C. californica is able to raft on kelp (Morris et al. 1980), and has been recorded on man-made structures such as rafts, settlement ropes and biofouling prone assemblages on ship hulls. Of interest is the recent rapid expansion of Caprella californica in Australian waters from its first recorded sighting in Sydney Harbour in 2002, to several recorded sightings over the last 4 years at Cockburn Sound, Western Australia, Hobsons Bay, Victoria, and the Port of Cairns, Queensland.     

Competitive displacement and predation between introduced and native mud snails

Experimental field and laboratory studies indicate that Cerithidea californica, a native mud snail, is restricted to only a portion of its normal habitat range in San Francisco Bay as a result of direct interactions with an introduced ecological equivalent, Ilyanassa obsoleta. The native snail typically inhabits marsh pans, tidal creeks and mudflats in estuaries along the Pacific coast. However, in San Francisco Bay it is confined to pans for most of the year, while the non-native snail inhabits the creeks and mudflats. Experiments and field monitoring demonstrate that this abnormal distribution pattern is caused by 1) interference competition for space in the form of an adult-adult behavioral avoidance by C. californica in the presence of invading I. obsoleta, and 2) predation by I. obsoleta on the eggs and juveniles of C. californica. The competitive exclusion of C. californica by I. obsoleta has not led to the extinction of the native snail because of the existence of a refuge for C. californica in pan habitats, beyond the physiological tolerances of I. obsoleta. As a consequence of the seasonal migrations of both species and changes in abiotic factors along the habitat gradient, repeated competitive displacements, rather than a one-time competitive exclusion, are observed between these two species. This is the first documented case of the competitive displacement of an endemic marine intertidal species by an introduced ecological equivalent.     

BIODIVERSITY RESEARCH: Genetic diversity in two introduced biofouling amphipods (Ampithoe valida & Jassa marmorata) along the Pacific North American coast: investigation into molecular identification and cryptic diversity

Aim We investigated patterns of genetic diversity among invasive populations of Ampithoe valida and Jassa marmorata from the Pacific North American coast to assess the accuracy of morphological identification and determine whether or not cryptic diversity and multiple introductions contribute to the contemporary distribution of these species in the region. Location Native range: Atlantic North American coast; Invaded range: Pacific North American coast. Methods We assessed indices of genetic diversity based on DNA sequence data from the mitochondrial cytochrome c oxidase subunit I (COI) gene, determined the distribution of COI haplotypes among populations in both the invasive and putative native ranges of A. valida and J. marmorata and reconstructed phylogenetic relationships among COI haplotypes using both maximum parsimony and Bayesian approaches. Results Phylogenetic inference indicates that inaccurate species‐level identifications by morphological criteria are common among Jassa specimens. In addition, our data reveal the presence of three well supported but previously unrecognized clades of A. valida among specimens in the north‐eastern Pacific. Different species of Jassa and different genetic lineages of Ampithoe exhibit striking disparity in geographic distribution across the region as well as substantial differences in genetic diversity indices. Main conclusions Molecular genetic methods greatly improve the accuracy and resolution of identifications for invasive benthic marine amphipods at the species level and below. Our data suggest that multiple cryptic introductions of Ampithoe have occurred in the north‐eastern Pacific and highlight uncertainty regarding the origin and invasion histories of both Jassa and Ampithoe species. Additional morphological and genetic analyses are necessary to clarify the taxonomy and native biogeography of both amphipod genera.     

Two New Species of Interstitial Marine Triclads from the North American Pacific Coast, with Comments on Evolutionary Trends and Systematics in Tricladida (Turbellaria)

Holmquist, Ch. and Karling, T. G. (Section of Invertebrate Zoology, Swedish Museum of Natural History, Stockholm, Sweden.) Two new species of marine triclads from the North American Pacific coast, with comments on evolutionary trends and systematics in Tricladida (Turbellaria). Zool. Scripta 1(3–4): 175–184, 1972.–Two marine triclads, Oregoniplana opisthopora gen. et sp.n. and Pacificides psammophilus gen. et sp.n. are described from the Pacific coast of USA. They are inhabitants of sand in the surf zone. They are provisionally included in the family Procerodidae but their anatomy is aberrant in several respects; they elucidate some evolutionary trends as well as some unsatisfactory points in the systematics of the aquatic triclads.     

Evolutionary and biogeographical patterns within the smelt genus Hypomesus in the North Pacific Ocean

Aim We address questions about trans‐Pacific distributions of marine organisms and the North Pacific Ocean as a centre of marine biodiversity through a phylogenetic and biogeographical study of a pan‐Pacific genus of Northern Hemisphere smelts (Hypomesus, Pisces: Osmeridae). Location North Pacific Ocean. Methods Relationships of the five species of Hypomesus from throughout the North Pacific were reconstructed through maximum likelihood and Bayesian phylogenetic analyses of sequence data from two mitochondrial (cytb, 16S) and three nuclear (ITS2, S71, RAG1) gene regions of five to 25 individuals per species, totalling 3588 characters. The resulting phylogenies were used to test hypotheses of species relationships and geographical origins using both dispersal‐based and maximum likelihood methods for inferring ancestral areas (lagrange ). Cytb sequence divergence and a Bayesian approach (beast ) were used to estimate the timeframe of Hypomesus evolution, which was compared with work on similarly distributed taxa. Results Hypothesized trans‐Pacific Ocean relationships based on lateral line scale counts were not supported by the phylogeny, suggesting parallel evolution of this phenotype, although we found one such relationship between the western H. japonicus and the two eastern Pacific species (H. pretiosus and H. transpacificus). Dispersalist approaches rejected an early proposal of a double‐compression vicariant mechanism as well as an eastern Pacific origin. Results from the lagrange analysis suggested a more widespread ancestor, although also supporting a role for the western Pacific. Divergence estimates suggested that most splits between species occurred in the mid‐Miocene, and the most recent speciation event, between the eastern Pacific species, occurred in the Pliocene to early Pleistocene. Main conclusions Our molecular data indicate that the character historically used to define relationships within Hypomesus, lateral line scale count, does not reflect ancestry within the genus. Biogeographical reconstructions suggest an important role for the western North Pacific in the diversification of Hypomesus. While uncertainty remains over the date of origin for this genus, estimates place the divergences during periods of climatic cooling that have been important in generating diversity in a number of similarly distributed organisms. Additional comparative data will provide further insight into the relative importance of the western region in generating diversity in the North Pacific Ocean.     

Gene flow in the anemone Anthopleura elegantissima limits signatures of local adaptation across an extensive geographic range

Species inhabiting marine environments face a wide range of environmental conditions that vary spatially across several orders of magnitude. The selective pressures that these conditions impose on marine organisms, in combination with potentially high rates of gene flow between distant populations, make it difficult to predict the extent to which these populations can locally adapt. Here, I identify how selection and gene flow influence the population genetic structure of the anemone Anthopleura elegantissima along the Pacific coast of North America. Isolation by distance is the dominant pattern across the range of this species, with a genetic break near Pt. Conception, CA. Furthermore, demographic modelling suggests that this species was historically confined to southerly latitudes before expanding northward. Outlier analyses identify 24 loci under selection (out of ~1,100), but the same analysis on simulated genetic data generated using the most likely demographic model erroneously identified the same number of loci under selection, if not more. Taken together, these results suggest that demographic processes are the dominant force shaping population genetic patterns in A. elegantissima along the Pacific coast of North America. I discuss these patterns in terms of the evolutionary history of A. elegantissima, the potential for local adaptation, and their consequences with respect to interactions with the endosymbiont Breviolum muscatinei across their geographic range.     

Cryptic species in Pacific sipunculans (Sipuncula: Phascolosomatidae): east‐west divergence between non‐sister taxa

Cryptic diversity, i.e. diversity observable in genetic but not in morphological traits, is prevalent in marine invertebrates and presents one of the greatest obstacles to obtaining accurate estimates of species richness. Sipunculans, commonly called peanut worms, are marine annelids in which high levels of cryptic diversity have previously been documented. In this study, we use genetic identification techniques to examine divergence of two lineages of Pacific sipunculans, both known under the name Phascolosoma agassizii. One lineage is isolated to the eastern Pacific coast while the other one inhabits the western Pacific coast. These clades are reciprocally monophyletic and are not recovered as sister taxa, suggesting relatively early divergence within Phascolosoma. Furthermore, we did not find support for a genetic distinction between the western Pacific Phascolosoma agassizii agassizii and Phascolosoma agassizii kurilense, a subspecies reported from the Kuril Islands. Considering that the type locality for P. agassizii is in the Eastern Pacific, we suggest that the western clade, including the samples from the Kuril islands, represent a new, undescribed species.     

Coccolithophorids from the west coast of Baja California, Mexico

Studies on coccolithophorids in Mexico are rather scarce, probably due to the use of traditional methods for studying marine phytoplankton (e.g. collection, preservation and analysis). This is the first study of the coccolithophorid flora from west coast of Baja California, Mexico. Bottle samples (4 l) were taken at various depths (5, 25 and 50 m), at fixed stations located on perpendicular transects along the west coast of Baja California, considering three different zones: North, Central and South. A total of 32 samples were studied by optical and scanning electron microscopy, yielding 24 taxa identified (17 species and 5 nominal varieties, plus 2 different varieties). The coccolithophorid assemblages are considered subtropical and coastal (with many cosmopolitan taxa). Emiliania huxleyi and Gephyrocapsa oceanica were the most abundant (relative abundance) and widespread species in the study area. We report 15 new records for the Mexican Pacific. The zonal and vertical distribution of some taxa are briefly discussed, as well as the taxonomy of Rhabdosphaera claviger, Helicosphaera carteri, H. hyalina and related taxa.     

Diversity and distribution of foliose Bangiales (Rhodophyta) in West Greenland: a link between the North Atlantic and North Pacific

Greenland is a continental island in the northern part of the North Atlantic where the foliose Bangiales flora is poorly known. It is an important area for the study of algal biogeography because of the region’s glacial history, in which Greenland has been alternately exposed to or isolated from the North Pacific via the Bering Strait. A molecular study using 3′ rbcL + 5′ rbcL–S sequences was undertaken to assess the diversity of foliose Bangiales on the west coast of Greenland and rbcL sequences were used to study the Greenland flora in a larger phylogenetic and floristic context. New and historic collections document seven species in four genera from the west coast of Greenland. All species had a close link to North Pacific species, being either conspecific with them or North Atlantic–North Pacific vicariant counterparts.     

Athalamia hyalina (Sommerf.) S.Hatt. in Scotland,new to the British Isles

Abstract

The liverwort Athalamia hyalina (Sommerf.) S.Hatt. and the family Cleveaceae are reported as new to the British Isles from the eastern Scottish Highlands. The Scottish plants are described and illustrated and the significance of the discovery is assessed. In Scotland, Athalamia hyalina occurs on thin soil on eroding limestone ledges in a montane habitat with a continental climate. It is in active growth in the winter months, producing spores in spring. Its range is restricted but it occurs within a protected area and is not threatened at present. The species is widespread in the northern hemisphere.