Localisation of gamma aminobutyric acid (GABA)-like immunoreactivity in the echinoderm Asterias rubens

Gamma amino butyric acid (GABA) is believed to be the principal inhibitory neurotransmitter in the mammalian central nervous system, a function that has been extended to a number of invertebrate systems. We have used a specific antiserum raised against GABA to demonstrate GABA-like immunoreactivity in the radial nerve cord (RNC), tube feet and the digestive system of the asteroid Asterias rubens. In the RNC, immunoreactivity was restricted to ectoneural fibres and cell bodies while in the tube feet fibres were revealed in the basal nerve ring and longitudinal nerve. In the gut, extensive labelling was apparent in the basi-epithelial plexus as well as in mucosal perikarya.     

Localization of S1- and S2-like immunoreactivity in the nervous system of the brittle star Amphipholis squamata (Delle Chiaje 1828).

The recent isolation and characterization of the SALMFanide neuropeptides S1 GFNSALMFamide; and S2 (SGPYSFNSGLTFamide) from the sea stars. Asterias rubens and Asterias forbesi have initiated numerous studies on their morphological localization and distribution within the phylum Echinodermata. It has been shown by immunocytochemistry and radioimmunoassay that these peptides are widely distributed in the nervous system of some asteroids, echinoids and ophiuroids. A physiological approach has also shown that S1 and S2 potentiate the luminescence of the small ophiuroid Amphipholis squamata. In the present study. S1- and S2-like immunoreactivity have been localized in A. squamata by immunocytochemistry on both wholemount preparation and histological sections. The results reveal a widespread neuronal distribution of S1-like immunoreactivity in the circumoral ring, radial nerve cord, and tube feet. S1-like immunoreactivity was found to be associated with axons and cell bodies in both the ectoneural and hyponeural components of the nervous. S2-like immunoreactivity was detected only in the ectoneural plenus of the circumoral ring and radial nerve cord.     

The aboral haemal system of the sea star,Asterias rubens (Echinodermata,Asteroidea): An ultrastructural and histochemical study

Summary The aboral parts of the haemal system of the sea star Asterias rubens are described, based on light and electron microscopy. These parts are (1) the mesenteric strands along the pyloric caeca and the pyloric stomach, (2) the gastric haemal tufts, and (3) the aboral haemal ring. The mesenteric haemal strands are very limited in size and distribution and, therefore, do not seem to have a major function in nutrient translocation. The myoepithelial cells of the gastric haemal tufts have the typical features of choanocytes; their ultrastructural characteristics corroborate the possible absorptive role of the gastric haemal tufts. The myoepithelial cells of the aboral haemal ring often show distinct apical bulbs of cytoplasm suggesting apocrine secretion of PAS-positive materials which are found in the surrounding aboral coelomic ring. These cells contain large stores of particulate glycogen and typical 1–2 m electrondense globules.The ground substance of the haemal tissues, which contains collagen fibers, reticular fibrils, and numerous amoeboid phagocytes, has been analyzed histochemically. Sulfated glycosaminoglycans are almost completely absent; the predominant components are polysaccharides, proteins, and/or glycoproteins. Lipids have not been demonstrated.The possible functions of the haemal tissues and associated coelomic channels are discussed.     

A comparative study on the influence of manganese on the bactericidal response of marine invertebrates

Manganese, Mn, is a naturally abundant metal in marine sediments. During hypoxic conditions the metal converts into a bioavailable state and can reach levels that have been shown immunotoxic to the crustacean Nephrops norvegicus. For this species it has previously been shown that exposure to 15 mg L⁻¹ of Mn decreased the number of circulating haemocytes while it for the echinoderm Asterias rubens increased the number of coelomocytes. Here, we compared if five days of exposure to the same concentration of Mn affects the bactericidal capacity of these two species and the mollusc Mytilus edulis when inoculated with the bacterium Vibrio parahaemolyticus. Viable counts of the bacteria were investigated at a time-course post-injection in the blood and the digestive glands of Mn-exposed and un-exposed (controls) animals. Accumulation of Mn was also analyzed in these tissues. When exposed to Mn the haemocyte numbers were significantly reduced in M. edulis and it was shown that the bactericidal capacity was impaired in the mussels as well as in N. norvegicus. This was most obvious in the digestive glands. These two species also showed the highest accumulation of the metal. In A. rubens the bactericidal capacity was not affected and the metal concentration was similar to the exposure concentration. After a recovery period of three days the concentration of Mn was significantly reduced in all three species. However, in M. edulis and N. norvegicus it was still double that of A. rubens which could explain the remaining bactericidal suppression observed in N. norvegicus. This study pointed out that exposure to such Mn-levels that are realistic to find in nature could have effects on the whole organism level, in terms of susceptibility to infections. The effect seemed associated to the accumulated concentration of Mn which differed on species level.     

Secretory Radial Glia in the Ectoneural System of the Sea Star Asterias rubens (Echinodermata)

Previous studies of epithelial nervous systems have focused on the neuronal elements, but generally neglected the origin of neuro–glial interactions. In this study, we use a polyclonal antiserum directed against Reissner's substance to label non-neuronal bipolar cells in the ectoneural part of the radial nerve cord in the sea star Asterias rubens. Ultrastructural results show secretory activity in these bipolar cells. Immunolabelled material is released into the extracellular matrix in the hyaline layer as well as in the region of the basal end-feet. As a first step towards characterising the antigen, a specific protein band of 36 kD was demonstrated with immunoprecipitation. Cells of this type: (1) traverse the epithelium to full extent from the outer surface to the basal lamina; (2) carry a single apical cilium; (3) contain conspicuous bundles of intermediate filament; (4) produce a secretion which is, at least in part, homologous to the Reissner's substance which is produced by a primitive radial glia cell type in chordates. It is concluded that the bipolar cells in the ectoneural part of the surface epithelium of the sea star Asterias rubens are secretory radial glia, which evidently have a common origin to the radial glia which secretes Reissner's substance in chordates.     

Über den Feinbau des hyponeuralen Nervensystems des Seesternes (Asterias rubens L.)

Zusammenfassung Langes Nerv, ein Teil des hyponeuralen Nervensystems der Asteroiden, wurde licht-, fluoreszenz- und elektronenmikroskopisch untersucht. Er zeigt die typische Gliederung in Kern- und Faserschicht. Die großen unipolaren Ganglienzellen reichen mit kolbenförmigen Ausläufern in das Cölom. Ihre basalen Fortsätze ziehen in die Faserschicht. Cölomepithelzellen liegen den Nervenzellen in unregelmäßigen Abständen als Deckzellen kappenartig auf oder sind als Stützzellen ausgebildet. Deck- und Stützzellen werden als Gliazellen aufgefaßt. Unterhalb der Kernschicht wurden licht- und elektronenmikroskopisch Zellen beobachtet, die für neurosekretorische Elemente gehalten werden. Der Feinbau der erwähnten Zelltypen wird beschrieben und diskutiert. Der histochemische Nachweis auf biogene Amine in Langes Nerv fiel negativ aus.

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The fine structure of the hyponeural nerve system of the starfish (Asterias rubens L.)

Summary The nerve of Lange, part of the starfish hyponeural nervous system, was investigated with the light-, fluorescence- and electron microscopes in Asterias rubens. It consists of two layers, one containing perikarya, the other fibres. The big nerve cells are unipolar and possess club-shaped processes which extend into the coelom. At their basis, the axon merges into the fibrous layer. Irregularly spaced coelomic epithelial cells cover partly the ganglion cells or constitute supporting elements. Covering and supporting cells are interpreted to represent glia cells. Underneath the perikarya layer, cells have been found by both the light and electron microscopes which are considered to be neurosecretory elements. The fine structure of the various cell types is described and discussed. Histochemical tests for biogenic amines were negative.

Herrn Prof. Dr. G. Birukow zum 60. Geburtstag gewidmet.     

Anatomy of the ovaries of the starfish Asterias rubens (Echinodermata)

Summary The ovaries of the starfish Asterias rubens were studied histologically and ultrastructurally. The reproductive system in female specimens consists of ten separate ovaries, two in each ray. Each ovary is made up of a rachis with lateral primary and secondary folds: the acini maiores and acini minores. The ovarian wall is composed of an outer and an inner part, separated by the genital coelomic sinus. The ovarian lumen contains oocytes in various phases of oogenesis, follicle cells, nurse cells, phagocytosing cells and steroid-synthesizing cells.Oogenesis is divided into four phases: (i) multiplication phase of oogonia, (ii) initial growth phase of oocytes I, (iii) growth phase proper of oocytes I, and (iv) post-growth phase of oocytes I. The granular endoplasmic reticulum and the Golgi complex of the oocytes appear to be involved in yolk formation, while the haemal system, haemal fluid and nurse cells may also be important for vitellogenesis. The haemal system is discussed as most likely being involved in synchronizing the development of the ovaries during the annual reproductive cycle and in inducing, stimulating and regulating the function of the ovaries.Steroid-synthesizing cells are present during vitellogenesis; a correlation between the presence of these cells and vitellogenesis is discussed.     

Impact scenario for the invasive red king crab <Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis> (Tilesius, 1815) (Reptantia,Lithodidae) on Norwegian,native, epibenthic prey

Large invasive predators like the king crab, Paralithodes camtschaticus, deserve particular attention due to their potential for catastrophic ecological impact on recipient communities. Conspicuous, epibenthic prey species, such as the slow growing commercial scallop Chlamys islandica, are particularly exposed to the risk of local extinction. A research program integrating experiments and field monitoring is attempting to predict and track the impact of invasive king crab on scallop beds and associated fauna along the north Norwegian coast. The claw gape of the crab shows no limitations in handling the flat-bodied scallop. However, the potential impact of the crab on scallop may depend on the availability of other calcified prey associated with scallop beds, such as the sea star, sea urchin, and blue mussel, all species recorded in the diet of P. camtschaticus. To address this issue, a laboratory experiment on foraging behaviour of P. camtschaticus was conducted. The experimental results show that all size classes of red king crab prefer scallops, but small juveniles and medium sized crabs demonstrate active selection for starfish (Asterias rubens) that equals or surpasses the electivity of the large crab. The selection of sea urchin (Strongylocentrotus droebachiensis) and blue mussel (Mytilus edulis) is slightly positive or neutral for the three crab size classes. These results suggest that scallop beds with a rich associated fauna are less vulnerable to red king crabs predation and possibly more resilient than beds with few associated species. Also, crab size distribution is likely relevant for invasion impact, with increasing abundance of small and medium sized crabs being detrimental for alternative calcified prey associated with scallop beds. Successive stages of crab invasion will see an acceleration of scallop mortality rates associated with (i) decreasing availability of alternative prey, due to protracted predation pressure intensified by recruitment of juvenile crabs, and (ii) increased number of large crabs. Estimates of crab density and intake rates suggest that the accelerated loss rates will eventually endanger scallop beds persistence.     

Cellular Responses of Congenital Immunity in the Starfish <Emphasis Type="Italic">Asterias rubens</Emphasis>

The work deals with analysis of changes of cellular defense factors in the starfish Asterias rubens in response to injection of human erythrocytes (HE). The number of circulating coelomocytes, dynamics of their production of active oxygen forms, activity of peroxidase, and dynamics of elimination of human hemoglobin from coelomic fluid were estimated before immunization with HE as well as at 6–144 h. The number of coelomocytes was counted in Goryaev chamber, production of active oxygen forms was determined in the test of spontaneous and zymosan-induced reduction of Tetrazolium Nitro Blue, peroxidase activity—in a color enzymatic reaction. Time of human hemoglobin elimination from the coelomic fluid was determined by spectrophotometric method by hemoglobin binding with acetone cyanohydrin with formation of a colored product. It is revealed that injection of human erythrocytes into the starfish Asterias rubens leads to a decrease of the number of coelomocytes in 24–96 h and to an increase of their specific production of active oxygen forms in 96–120 h after the HE injection. In coelomic fluid of Asterias rubens the presence of peroxidase activity is established. The circulation time of human hemoglobin released from erythrocytes in coelomic fluid of these animals does not exceed 24 h. It is suggested that the cellular defense reactions are the major factor of the starfish congenital immunity.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 2, 2005, pp. 107–113.Original Russian Text Copyright © 2005 by Kudryavtsev, D’yachkov, Kazakov, Kanaikin, Kharazova, Polevshchikov.     

Structural analysis of the starfish SALMFamide neuropeptides S1 and S2: The N-terminal region of S2 facilitates self-association

The neuropeptides S1 (GFNSALMFamide) and S2 (SGPYSFNSGLTFamide), which share sequence similarity, were discovered in the starfish Asterias rubens and are prototypical members of the SALMFamide family of neuropeptides in echinoderms. SALMFamide neuropeptides act as muscle relaxants and both S1 and S2 cause relaxation of cardiac stomach and tube foot preparations in vitro but S2 is an order of magnitude more potent than S1. Here we investigated a structural basis for this difference in potency using spectroscopic techniques. Circular dichroism spectroscopy showed that S1 does not have a defined structure in aqueous solution and this was supported by 2D nuclear magnetic resonance experiments. In contrast, we found that S2 has a well-defined conformation in aqueous solution. However, the conformation of S2 was concentration dependent, with increasing concentration inducing a transition from an unstructured to a structured conformation. Interestingly, this property of S2 was not observed in an N-terminally truncated analogue of S2 (short S2 or SS2; SFNSGLTFamide). Collectively, the data obtained indicate that the N-terminal region of S2 facilitates peptide self-association at high concentrations, which may have relevance to the biosynthesis and/or bioactivity of S2 in vivo.     

The relationship between specific dynamic action (SDA) and growth in the common starfish,Asterias rubens L.

Summary After feeding the metabolic rate of animals rapidly increases to a peak level and thereafter slowly declines to pre-feeding level. This phenomenon has been termed the specific dynamic action of food. The processes causing the increase in metabolism are uncertain. In Asterias rubens there was a close relationship between the magnitude of SDA and growth rate (coefficient of determination=r ²=0.85), suggesting that the increased metabolic expenditure following feeding represent the energetic cost of growth.     

Benefit from an invader: American slipper limpet <Emphasis Type="Italic">Crepidula fornicata</Emphasis>reduces star fish predation on basibiont European mussels

Introduced species have recently become a major concern in ecological research and aquatic conservation. This is due to an increasing appearance of introduced species at a global scale and a multitude of negative impacts on native biota. However, impacts of introduced species are not necessarily only negative. The epizootic American slipper limpet Crepidula fornicata, native at North American Atlantic shores, was introduced to Europe in the 1870s and is now widespread along the Atlantic coast of Europe. Negative effects like trophic and spatial competition have been reported. In its major basibiont in the Wadden Sea, the blue mussel Mytilus edulis, attached limpets reduce survival and growth. However, a laboratory experiment also showed sea star (Asterias rubens) predation on mussels with limpet epigrowth to be three times lower than in unfouled mussels. Hence, although negatively affected by C. fornicatain one way, this epigrowth is beneficial for fouled mussels in another. This indicates that the actual impact of an introduced species is a complex interplay of positive and negative effects which may only be revealed experimentally.     

Effect of excretion-secretion products of some fouling species on the biochemical parameters of blue mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> L. (Mollusca: Bivalvia) in the White Sea

The effect of excretion-secretion products (ESP) of five abundant fouling invertebrate species (bivalve mollusks Hiatella arctica and Mytilus edulis, solitary ascidia Styela rustica, sponge Halichondria panacea, and sea star Asterias rubens, inhabiting the White Sea) on the biochemical status of blue mussel M. edulis was assessed by the dynamics of lysosomal enzymes activity (nucleases, glycoside hydrolases, and cathepsins). ESP of conspecific species had no effect on the metabolism of the mollusks of this species. ESP of A. rubens, S. rustica, and H. panicea activated the same enzymes. First, acid RNase and glycoside hydrolases activity increased, but in different ways. The metabolites of H. arctica affected the activity of proteometabolism enzymes.     

Humoral responses of congenital immunity in the starfish <Emphasis Type="Italic">Asterias rubens</Emphasis>

The work presents analysis of changes of humoral protective factors in the starfish Asterias rubens in response to injection of human erythrocytes (HE). The total protein concentration and the titers of hemagglutinins and hemolysins in starfish coelomic fluid, as well as the time of human hemoglobin elimination from circulation were estimated for 6–144 h of the experiment. The hemagglutinin titer was determined in hemagglutination reactions, the hemolysin titer—in hemolysis reaction. Time of human hemoglobin elimination from coelomic fluid was determined in a color enzymatic reaction. The starfish coelomic fluid was revealed to contain soluble factors that are able to interact with antigen— antibody complexes of mammals and have an opsonizing activity. It is established that injection of HE does not change the total protein concentration per 1 ml coelomic fluid, but affects dynamics of changes of the hemagglutinins titer. Time of hemoglobin elimination from circulation does not exceed 24 h. Humoral factors of coelomic fluid of the starfish Asterias rubens play an auxiliary role in congenital immunity reactions.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 1, 2005, pp. 23–28.Original Russian Text Copyright © 2005 by Kudryavtsev, Dyachkov, Kazakov, Kanaikin, Kharazova, Polevshchikov.     

Associational resistance of fouled blue mussels (<Emphasis Type="Italic">Mytilus edulis</Emphasis>) against starfish (<Emphasis Type="Italic">Asterias rubens</Emphasis>) predation: relative importance of structural and chemical properties of the epibionts

Several epibiotic species reduce starfish (Asterias rubens) preference for the blue mussel Mytilus edulis in the Baltic. The aim of this study was to reveal whether this associational resistance was caused by structural or chemical aspects of the different epibionts. To assess structural epibiont effects, an in situ experiment was conducted with unfouled mussels and mussels equipped with artificial epibionts (dummies) exposed to natural predation by A. rubens. The chemically inert dummies closely matched the structural properties of the locally common epibionts Balanus improvisus (barnacle), Ceramium strictum (red alga), Halichondria panicea (sponge), and Laomedea flexuosa (hydrozoan). Starfish fed indiscriminately in all treatments. Chemical effects of epibionts on the attractiveness of mussels for A. rubens were investigated by incorporating freeze-dried epibionts or mussel tissue into Phytagel pellets at natural concentrations. Starfish were allowed to choose among these structurally similar but chemically different prey items in an in vitro experiment. The predators exhibited significant preferences among the food pellets, which closely matched their preferences for corresponding natural mussel–epibiont associations. Thus, chemical aspects of epibionts appear to play a larger role in this associational resistance than do structural aspects. Implications of these indirect interactions for benthic communities are discussed.Communicated by H.-D. Franke     

Interactive effects of haloclines and food patches on the vertical distribution of 3 species of temperate invertebrate larvae

In laboratory experiments, we examined the effect of haloclines and determined whether the presence of food patches overrides this effect on larval vertical distribution of the sea star Asterias rubens, the sea urchin Strongylocentrotus droebachiensis and the mussel Mytilus edulis. We experimentally constructed haloclines in which the salinity of the bottom water layer was 35 and that of the top layer was 21, 24, 27, and 30 (21/35, 24/35, 27/35, and 30/35) for A. rubens and S. droebachiensis, and 24, 27, 30 and 32 (24/35, 27/35, 30/35, and 32/35) for M. edulis. For each species and stage, additional halocline treatments (A. rubens: 24/32 and 27/32; 4-arm S. droebachiensis: 21/29 and 24/32; 6-arm S. droebachiensis: 24/29 and 24/32; M. edulis: 27/32 and 30/32) were used to determine whether the larval response to inhibitory salinity gradients was due to the absolute salinity of the top layer or the relative salinity difference between the two layers. Also, we measured the density of A. rubens and M. edulis to determine whether the specific gravity of larvae can explain the observed vertical distributions. Larvae aggregated at and below the halocline and these aggregations were more pronounced with increasing strength of the vertical salinity gradient. Threshold salinities in the top layer which inhibited ~ 100% of the larvae from crossing the halocline were 24 for A. rubens and M. edulis, and 21 for S. droebachiensis. These distributional patterns were not the result of larval density, which was greater than all treatment water densities for M. edulis and S. droebachiensis and lower for A. rubens. The effect of the presence of a food patch at inhibitory haloclines (A. rubens: 24/35 and 27/35; 4-arm S. droebachiensis: 21/34 and 24/34; M. edulis: 27/35) was determined by using three algal densities: 0, 5000 or 10 000 cells ml^- 1Thalassiosira pseudonana in either the top or the bottom water layer. For both A. rubens and M. edulis, the number of larvae at the halocline increased in the presence of a food patch, but this effect did not depend on algal density in the patch. For 4-arm S. droebachiensis, there was no effect of the presence of a food patch on larval vertical distribution. Our results suggest that low salinity may act as a barrier to vertical movement and that the presence of food patches above the halocline may strengthen the larval aggregation response to inhibitory haloclines.     

Density-dependent ant attendance and its effects on the parasitism of a honeydew-producing scale insect,Ceroplastes rubens

The intensity of attendance by a honeydew-foraging ant, Lasuis niger, on the red wax scale insect, Ceroplastes rubens, was estimated at different manipulated densities in the field. The time that individual ants were present and the total attendance time (seconds x number of ants) of ants on scale-infested twigs significantly increased as the density of C. rubens increased, i.e. ant attendance was density dependent. To determine the effects of density dependence of ant attendance on parasitism of C. rubens by Anicetus beneficus, we measured parasitism rates in the field at different density levels of C. rubens both with ant attendance and with ants excluded. Parasitism rates were higher when ants were excluded, at each density level. Although the parasitism rate significantly deceased as scale density increased, whether or not ants attended, the difference in parasitism rate between density levels was strikingly less without ant attendance. Therefore, the density-dependent decrease of parasitism rate was more pronounced with ant attendance. Mortality not due to parasitism showed density dependence in both conditions and did not change when ants were excluded. These results indicate that attending ants reduce parasitism and that, as a consequence of the density dependence of ant attendance, the efficiency of reduction of parasitism by ants is enhanced at higher densities of C. rubens.     

The Influence of Salinity on Early Ontogeny of the Mussel Mytilus edulisand the Starfish Asterias rubensfrom the White Sea

The influence of increased and decreased salinity on early larvae of the mussel Mytilus edulisL. and the starfish Asterias rubensfrom the White Sea is studied. Fertilized egg cells, embryos, larvae, and yearlings of the two species were compared. Salinity tolerance changes with the stage of development of mussels and starfish. Morphological changes occurring in eggs and embryos exposed to extremely high and low salinities are reported.     

Interference of host plant morphology and phenology and their correlation with abundance patterns of the leaf galling sawfly <Emphasis Type="Italic">Pontania proxima</Emphasis>

The host taxon preference of Pontania proxima (Serville 1823) (Tenthredinidae, Hymenoptera) was investigated by observing densities of galls on previously genotypically and phenotypically characterized clones representing three taxa of a hybrid complex, i.e., Salix alba, Salix × rubens, and Salix fragilis. Gall densities among these three taxa were observed by using two experimental designs: (1) an indoor experiment in a greenhouse flight cage, and (2) an outdoor experiment on a plantation of cuttings. Subsequently, observed gall densities were related with selected, characteristic phenotypical properties of the host plants. In the indoor experiment, S. fragilis was clearly preferred by P. proxima, while in the outdoor experiment, S. × rubens revealed the highest gall densities. The factor “foliation start” was excluded in the indoor experiment, but best explained the preference of S. × rubens in the outdoor experiment. The results of a linear regression model affirmed on the one hand that morphological properties should be expected as relevant signals during the host plant selection process of P. proxima. On the other hand, it was shown that other phenotypical factors such as foliation start in spring contribute to an interference of factors being relevant for host plant selectivity. The earlier foliation start of the morphological intermediate S. × rubens in the outdoor experiment shifts resource availability towards that taxon at an early oviposition phase of P. proxima and therefore entails a different gall distribution pattern with a preference for the hybrid under natural conditions.     

CULTURE STUDIES ON THE RELATIONSHIP BETWEEN SCHIZYMENIA AND HAEMATOCELIS (GIGARTINALES,RHODOPHYCEAE) FROM THE PACIFIC COAST OF NORTH AMERICA1

Carpospores from Schizymenia pacifica (Kylin) Kylin (Gymnophlaeaceae) from California formed crusts anatomically identical to Haematocelis rubens J. Agardh (Cruoriaceae). Tetraspores of H. rubens from Monterey, California, and Baja California, Mexico, germinated to form basal discs from which arose upright multiaxial blades with a filamentous medulla and cortical gland cells. Pro-carps and spermatangia were present on the same blades; subsequently, cystocarps characteristic of Schizymenia pacifica developed. Re-examination of herbarium specimens suggests that the foliose tetrasporangial phases previously reported as S. pacifica are referable to Halymenia, Dilsea, Cryptonemia, or Turnerella. Schizymenia pacifica (type locality: San Juan Islands, Washington) thus is considered to be the gametophyte in the life history of Haematocelis rubens (type locality: Brest, France), which has also been reported to be the tetrasporophyte of S. dubyi (Chauvin ex Duby) J. Agardh (type locality: Cherbourg, France). Atlantic and Pacific gametophytes and tetrasporophytes are anatomically very similar, suggesting that only one species is involved, but critical studies must be made before a decision on this taxonomic question can be reached. Haematocelis zonalis Dawson et Neushul (type locality: Anacapa Island, California) is considered to be a growth form of the tetrasporangial phase of S. pacifica.