Molecular phylogeny of the Sphaerophorus globosus species complex

The Sphaerophorus globosus complex (Lecanorales, lichenized Ascomycota) shows a large morphological variation, and three relatively distinct morphotypes can be distinguished in parts of the distribution area. Here, we utilize a multigene‐based maximum‐parsimony approach (nITS+ LSU rDNA, mtSSU rDNA, β‐tubulin, and actin) to investigate whether these morphotypes constitute distinct species. The results show that there are at least two well‐supported monophyletic groups that we interpret as phylogenetic species within the S. globosus complex. These species do not completely correspond to the predefined morphotypes. One group, an apparently undescribed species, contains noncoralloid specimens from the North American Pacific Northwest. The other group, S. globosus, consists of two well‐supported monophyletic groups: one contains coralloid epiphytic specimens from the North American Pacific Northwest that are morphologically indistinguishable from epiphytic specimens from Europe and are presently interpreted as belonging to the same species and the other is morphologically variable and contains terrestrial specimens from Europe, North America, and southernmost South America and coralloid epiphytic and epilithic specimens from Europe. The results suggest that the population in southernmost South America originated by long‐distance dispersal from arctic populations in the Northern Hemisphere.     

Pseudo-nitzschia pungens (Bacillariophyceae): A cosmopolitan diatom species?

Genetic, reproductive and morphological variation were studied in 193 global strains of the marine diatom species Pseudo-nitzschia pungens (Grunow ex Cleve) Hasle to assess potential intraspecific variation and biogeographic distribution patterns. Genetic differentiation between allo- and sympatric strains was investigated using the ITS1–5.8S–ITS2 rDNA region. Three ITS clades were found. Clones of opposite mating type were sexually compatible within clades I or II, and viable F1 hybrid offspring were produced in crosses between them. The molecular differences between these clades were correlated with slight but consistent morphological differences. At present, nothing can be said about morphology and mating behavior for clade III clones because only ITS data were available. The three ITS clades showed different geographic distributions. Clade II was restricted to the NE Pacific, whereas clones belonging to clade III originated from geographically widely separated areas (Vietnam, China and Mexico). ITS clade I was recovered in all locations studied: the North Sea (Belgium, The Netherlands, France), the eastern and western N Atlantic (Spain, Canada), the NW and S Pacific (Japan, New Zealand) and the NE Pacific (Washington State). Clade I thus appears to be globally distributed in temperate coastal areas and provides the first strong evidence to date for the global distribution of a biologically, genetically and morphologically defined diatom species.     

An introduced population of Chorda asiatica (Chordaceae,Laminariales) in Puget Sound,Pacific coast of North America

Northeastern Pacific Ocean and northwestern Atlantic Ocean populations of Chorda species, which have not been examined in previous phylogenetic studies, were investigated. All specimens that were collected in Hood Canal, Puget Sound, WA, USA, Pacific coast of North America, showed identical ITS‐5.8S rDNA sequences, and they were included in the clade of Japanese Chorda asiatica. With morphological data added to the molecular data, they were identified as C. asiatica and were concluded to be non‐indigenous populations, most likely introduced with oyster spat together with Sargassum muticum. Specimens collected in New York, NY, USA, Atlantic coast of North America, were genetically closest to C. filum from Newfoundland and were identified as C. filum. The genetic divergence of the North Atlantic populations of C. filum was relatively small compared to that of Japanese C. asiatica considering their broader distributional ranges on both sides of the Atlantic.     

Species delimitation and DNA barcoding of Atlantic Ensis (Bivalvia,Pharidae)

Ensis Schumacher, 1817 razor shells occur at both sides of the Atlantic and along the Pacific coasts of tropical west America, Peru, and Chile. Many of them are marketed in various regions. However, the absence of clear autapomorphies in the shell and the sympatric distributions of some species often prevent a correct identification of specimens. As a consequence, populations cannot be properly managed, and edible species are almost always mislabelled along the production chain. In this work, we studied whether the currently accepted Atlantic Ensis morphospecies are different evolutionary lineages, to clarify their taxonomic status and enable molecular identifications through DNA barcoding. For this, we studied 109 specimens sampled at 27 sites, which were identified as belonging to nine of those morphospecies. We analysed nucleotide variation at four nuclear (18S, 5.8S, ITS1, and ITS2) and two mitochondrial (COI and 16S) regions, although the 18S and 5.8S regions were not informative at the species level and were not further considered. The phylogenetic trees and networks obtained supported all morphospecies as separately evolving lineages. Phylogenetic trees recovered Ensis at each side of the Atlantic as reciprocally monophyletic. Remarkably, we confirm the co‐occurrence of the morphologically similar E. minor (Chenu, 1843) and E. siliqua (Linné, 1758) along the NW Iberian coast, a fact that has been often overlooked. In South America, a relevant divergence between E. macha (Molina, 1792) individuals from Chile and Argentina was unveiled and suggests incipient speciation. We also confirm the occurrence of the North American species E. directus (Conrad, 1843) as far south as north‐eastern Florida. Among the genomic regions analysed, we suggest COI as the most suitable DNA barcode for Atlantic Ensis. Our results will contribute to the conservation and management of Ensis populations and will enable reliable identifications of the edible species, even in the absence of the valves. The name Ensis coseli Vierna nom. nov. is proposed to replace E. minor Dall, 1899 non (Chenu, 1843).     

rbcL sequences reveal multiple cryptic introductions of the Japanese red alga Polysiphonia harveyi

In Europe, the last 20 years have seen a spectacular increase in accidental introductions of marine species, but it has recently been suggested that both the actual number of invaders and their impacts have been seriously underestimated because of the prevalence of sibling species in marine habitats. The red alga Polysiphonia harveyi is regarded as an alien in the British Isles and Atlantic Europe, having appeared in various locations there during the past 170 years. Similar or conspecific populations are known from Atlantic North America and Japan. To choose between three competing hypotheses concerning the origin of P. harveyi in Europe, we employed rbcL sequence analysis in conjunction with karyological and interbreeding data for samples and isolates of P. harveyi and various congeners from the Pacific and North Atlantic Oceans. All cultured isolates of P. harveyi were completely interfertile, and there was no evidence of polyploidy or aneuploidy. Thus, this biological species is both morphologically and genetically variable: intraspecific rbcL divergences of up to 2.1% are high even for red algae. Seven rbcL haplotypes were identified. The four most divergent haplotypes were observed in Japanese samples from Hokkaido and south-central Honshu, which are linked by hypothetical 'missing' haplotypes that may be located in northern Honshu. These data are consistent with Japan being the centre of diversity and origin for P. harveyi. Two non-Japanese lineages were linked to Hokkaido and Honshu, respectively. A single haplotype was found in all North Atlantic and Mediterranean accessions, except for North Carolina, where the haplotype found was the same as that invading in New Zealand and California. The introduction of P. harveyi into New Zealand has gone unnoticed because P. strictissima is a morphologically indistinguishable native sibling species. The sequence divergence between them is 4-5%, greater than between some morphologically distinct red algal species. Two different types of cryptic invasions of P. harveyi have therefore occurred. In addition to its introduction as a cryptic sibling species in New Zealand, P. harveyi has been introduced at least twice into the North Atlantic from presumed different source populations. These two introductions are genetically and probably also physiologically divergent but completely interfertile.     

Species identification of Alnus (Betulaceae) using nrDNA and cpDNA genetic markers

One nuclear and three chloroplast DNA regions (ITS, rbcL, matK and trnH-psbA) were used to identify the species of Alnus (Betulaceae). The results showed that 23 out of all 26 Alnus species in the world, represented by 131 samples, had their own specific molecular character states, especially for three morphologically confused species (Alnus formosana, Alnus japonica and Alnus maritima). The discriminating power of the four markers at the species level was 10% (rbcL), 31.25% (matK), 63.6% (trnH-psbA) and 76.9% (ITS). For ITS, the mean value of genetic distance between species was more than 10 times the intraspecific distance (0.009%), and 13 species had unique character states that differentiated them from other species of Alnus. The trnH-psbA region had higher mean values of genetic distance between and within species (2.1% and 0.68% respectively) than any other region tested. Using the trnH-psbA region, 13 species are distinguished from 22 species, and seven species have a single diagnostic site. The combination of two regions, ITS and trnH-psbA, is the best choice for DNA identification of Alnus species, as an improvement and supplement for morphologically based taxonomy. This study illustrates the potential for certain DNA regions to be used as novel internet biological information carrier through combining DNA sequences with existing morphological character and suggests a relatively reliable and open taxonomic system based on the linked DNA and morphological data.     

Molecular identification of Anisakis simplex sensu stricto and Anisakis pegreffii (Nematoda: Anisakidae) from fish and cetacean in Japanese waters

Parasites morphologically consistent with Anisakis simplex sensu lato collected from the coast of Japan and Western North Pacific Ocean were examined by PCR-RFLP of the ITS region (ITS1, 5.8 subunit rRNA gene and ITS2) and mtDNA cox1. The RFLP patterns of rDNA generated by HinfI and HhaI showed that 100% of the larvae collected from Hokkaido and 94% of adults collected from Western North Pacific Ocean were identified as A. simplex sensu stricto. On the other hand, 97% of the larvae collected from Fukuoka prefecture were identified as A. pegreffii. A hybrid genotype was found in adults in Western North Pacific Ocean and larva in Fukuoka prefecture. These findings revealed that A. simplexs. str. is primarily distributed in the North Pacific Ocean and A. pegreffii is primarily distributed in the southern Sea of Japan. RFLP analysis of mtDNA cox1 showed different patterns between A. simplex s. str. and A. pegreffii after digestion with HinfI. This polymorphism obtained by RFLP analysis of mtDNA cox1 proved the usefulness as new genetic markers to distinguish two sibling species.     

Reassessment of the taxonomic status of Gelidium subfastigiatum (Gelidiales, Rhodophyta)

The taxonomic relationship between Gelidium elegans Kützing and Gelidium subfastigiatum Okamura, two morphologically similar species of the red algal genus Gelidium (Gelidiaceae) growing in the north‐western Pacific, was critically re‐examined. Gelidium subfastigiatum has been distinguished from G. elegans by its more robust thalli, which have antrorse tooth‐like branches, although their distinction has been said to be often difficult or impossible. We determined the nuclear encoded internal transcribed spacer 1 (ITS1) for 14 samples from eight populations of this G. elegans/ G. subfastigiatum complex, and two types of ITS1 sequences were found. Analysis of seasonal variations of subterminal portions of major branches revealed that this complex includes two groups: one possessing the type 1 ITS1 sequence and antrorse tooth‐like branches that are subterminally thickened and widened during only colder months, and another possessing the type 2 ITS1 sequence and thin and narrow branches throughout the year. These groups should be recognized as separate species; the former is assigned to G. subfastigiatum and the latter to G. elegans.     

DNA barcoding of European Herbertus (Marchantiopsida, Herbertaceae) and the discovery and description of a new species

DNA barcoding of a group of European liverwort species from the genus Herbertus was undertaken using three plastid (matK, rbcL and trnH-psbA) and one nuclear (ITS) marker. The DNA barcode data were effective in discriminating among the sampled species of Herbertus and contributed towards the detection of a previously overlooked European Herbertus species, described here as H. norenus sp. nov. This species shows clear-cut differences in DNA sequence for multiple barcode regions and is also morphologically distinct. The DNA barcode data were also useful in clarifying taxonomic relationships of the European species with some species from Asia and North America. In terms of the discriminatory power of the different barcode markers, ITS was the most informative region, followed closely by matK. All species were distinguishable by ITS alone, rbcL + matK and various other multimarker combinations.     

Phylogenetic relationships within Korthalsella (Viscaceae) based on nuclear ITS and plastid trnL-F sequence

The nuclear encoded internal transcribed spacer (ITS) region and the plastid encoded trnL-F region were sequenced for 25 populations of Korthalsella, a genus of reduced, monoecious, Old World misletoes. The molecular study confirms the hypothesis that branch shape and cladotaxy (the arrangement of branches with respect to their parent axis) are unreliable indicators of relationship in the genus and demonstrates that many of the taxa previously recognized are not monophyletic. Both gene regions identify three major subgroups within the genus and find lower level relationships within these subgroups highly correlated with geographic distance. An analysis based upon 18S and rbcL sequences identifies Ginalloa as the sister group to Korthalsella, which together with the branching order within the genus, indicates that Korthalsella originated in Papuasia and aids in elucidating evolution of the peculiar inflorescence structure. There are problems associated with species delimitation when evolutionary units are more restricted than morphological lineages, and justification is offered for recognizing only morphologically diagnosable monophyletic lineages as species. Varying substitution rates and differing modes of inheritance in ITS and trnL-F result in complementary utility of the two regions for elucidating infrageneric relationships in Korthalsella.     

Delineation of Chondrus (Gigartinales, Florideophyceae) in China and the origin of C. crispus inferred from molecular data

Complete nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) sequences were obtained for 18 Chondrus populations collected at 15 sites from eight countries worldwide. Pairwise comparisons with the multiple alignment revealed that intraspecific divergences of ITS sequences ranged from 0.3 to 1.8% in C. crispus Stackhouse (except for the entity SVLH from France) and from 0.0 to 0.6% in C. ocellatus Holmes, whereas interspecific divergences in Chondrus varied from 1.4 to 5.0%. Three phylogenetic methods (neighbour joining, maximum parsimony and maximum likelihood) confirmed three main lineages: the North Atlantic lineage containing entities of C. crispus from Canada, France, Germany, England, Portugal, Ireland and Wales; a second lineage comprising three species: C. sp. 1, C. armatus (Harvey) Yamada et Mikami, and C. pinnulatus (Harvey) Okamura from the Northern Pacific; and a third lineage containing just one species: C. ocellatus from the Northern Pacific. Chondrus yendoi Yamada et Mikami separated from other Chondrus species singly. nrDNA ITS data indicate that a previous assignment of C. sp. 2 to Mazzaella japonica (Mikami) Hommersand may be incorrect, and additional evidence is needed to resolve the generic placement of this entity. It is inferred from the nrDNA ITS data that three Chondrus species are presently known in China with two, C. ocellatus and C. nipponicus, in Qingdao and two, C. armatus and C. nipponicus, in Dalian. We hypothesize that the ancestor of North Atlantic C. crispus had a Pacific origin, and that the present distribution of C. crispus in the Atlantic Ocean correlates with a trans-Arctic dispersal and vicariance events associated with Pleistocene glaciation maxima.     

Hybridization studies in Bostrychia. 1: B. radicans (Rhodomelaceae, Rhodophyta) from Pacific and Atlantic North America

Bostrychia radicans(Montagne) Montagne is a pantropical/temperate red alga associated with mangroves and saltmarsh plants. Collections were made from a similar north-south geographic distribution along both the Pacific and Atlantic coasts of North America. Hybridization studies were performed with cultured isolates to assess the extent of interfertility and reproductive isolation along these two coastlines. All male and female gametophytes derived from single tetrasporophytes were intercompatible. Almost all isolates extending over 1500 km of coast line from northern Pacific Mexico are compatible, forming cystocarps that released viable carpospores. Even isolates which morphologically would be placed in two species [B. radicans and B. moritziana(Sender ex Kützing) J. Agardh], based on the presence or absence of monosiphonous branches, were capable of hybridizing. Crosses of isolates from the Atlantic USA showed a greater amount of incompatibility. Certain isolates were not compatible with any other isolates including isolates collected in close proximity (North Carolina isolates), while other isolates from the same locality were compatible (South Carolina). An isolate from South Carolina formed tetrasporophytes with isolates from Pacific Mexico but tetraspores were not viable. Certain incompatible crosses formed ‘pseudocystocarps’ but viable carposporophytes did not develop. Generalizations about reproductive isolation within a species must also consider differences between populations from different biogeographic regions that may reflect different paleoclimatological histories, founder effects and unique dispersal events.     

Intraspecific sterility barrier confirms that introduction of Sphaerotrichia divaricata (Phaeophyceae,Chordariales) into the Mediterranean was from Japan

Crossing studies revealed an intraspecific sterility barrier on the level of zygote formation between Japanese Sphaerotrichia divaricata and isolates of the same species from the Northeast Pacific and the North Atlantic. Because no consistent morphological differences exist between sporophytes from Japan and other areas, we propose not to distinguish the intersterile populations as different species. Japanese Sphaerotrichia and isolates from a recently detected population in the Étang de Thau, French Mediterranean coast, are interfertile. The crossing studies support the assumption that this Mediterranean population is a recent introduction from Japan.     

Biogeography and systematics of Hildenbrandia (Rhodophyta,Hildenbrandiales) in North America: inferences from morphometrics and rbcL and 18S rRNA gene sequence analyses

Morphometric analysis and phylogenetic analysis of sequences of the rbcL chloroplast gene (which codes for the large subunit of the ribulose-1,5-bisphosphate carboxylase/oxygenase enzyme) and the nuclear 18S ribosomal RNA (rRNA) gene were carried out on 26 specimens of marine and freshwater Hildenbrandia from North America. Nineteen marine specimens were collected from Alaska to Costa Rica on the Pacific coast and from Newfoundland to Connecticut on the Atlantic coast. Seven freshwater samples were collected from Texas, Costa Rica, St Lucia and Puerto Rico. Three groups of samples were distinguished by morphometric analysis: one containing all freshwater samples (H. angolensis Welwitsch ex West et West), one consisting of a marine sample with parallel tetrasporangial divisions (H. occidentalis Setchell ex Gardner) and one group with non-parallel tetrasporangial divisions (H. rubra (Sommerfelt) Meneghini. These groupings were partially incongruent with those obtained by analyses of the molecular data. Parsimony and distance analyses of the rbcL gene resulted in trees in which Atlantic and Pacific clades were largely resolved. However, an Alaskan sample was included in the Atlantic group, which may indicate a trans-Arctic invasion event. The freshwater samples were paraphyletic for the rbcL gene, among the marine collections, which supports the concept of multiple invasions establishing the freshwater populations in North America. The 18S rRNA gene sequence data indicate that the freshwater samples are monophyletic with the exception of the unresolved position of the H. occidentalis sample. The freshwater samples form a monophyletic clade when multiple outgroups are used. The rbcL data appear to be mutationally saturated above approximately 17% divergence, which makes interpretation of phylogenetic signal among distant groups difficult. This may be a result of the asexual reproduction of the alga.     

PCR primers for selective detection of intra-species variations in the bloom-forming cyanobacterium,Microcystis

Members of the cyanobacterial genus Microcystis commonly form blooms in eutrophic freshwater systems, and some produce cyclic heptapeptide hepatotoxins called microcystins, thereby often causing serious water management problems. Microcystis species were unified into the single Microcystis aeruginosa classification based on 16S rRNA gene sequences and DNA–DNA re-association experiments; however, the morphological features of the organisms differ in different culturing conditions. Here, we describe a new real-time quantitative PCR (qPCR) method of determining Microcystis intradiversity using the SYBR Green I assay. We analyzed 71 Microcystis 16S-23S rDNA internal transcribed spacer region (16S-23S ITS) sequences, designed three group-specific PCR primers that successfully selected a morphologically M. wesenbergii-like non-toxic group (Group-3), and differentiated between M. viridis-like toxic group (Group-4) and M. aeruginosa-like Group-1 organisms including toxic and non-toxic Microcystis strains. The primers covered 76% of the Microcystis 16S-23S ITS regions from all over the world (six continents) included in GenBank. We constructed a mixed culture with representative Microcystis strains from each group, and estimated their cell densities by qPCR over 7 weeks. Group-1 and Group-3 grew exponentially for 4 weeks; however, the growth of Group-4 declined after 2 weeks, revealing different growth properties for the Microcystis groups in the mixed culture. Finally, we applied this method to natural Microcystis blooms at four freshwater sites, and found the dominance of Group-1 in three blooms and of Group-3 in one bloom, thereby showing the geographically uneven distribution of Microcystis genotypes. The developed qPCR technique targeting the 16S-23S ITS region is both rapid and simple and is useful for selective quantification of group variations among sympatric Microcystis genotypes, such as in mixed cultures and the natural environment.     

Description of a new marine species of Askenasia Blochmann, 1895 (Ciliophora,Haptoria), with notes on its ecology

A marine planktonic ciliate, belonging to the genus Askenasia Blochmann, 1895, is described with notes on its distribution and ecology. Specimens of this new species were collected from four coastal sites across the northern hemisphere. Samples were collected between March and December, from depths of 1-20 m. Relatively low (< 1 ml(-1)) densities were recorded from Atlantic and Pacific Oceans and North Sea coastal sites, whereas samples from the English Channel suggested that this species has the ability to form blooms. Specimens were protargol-stained, revealing the key features of the genus, including the diagnostic sub-equatorial kinety belt consisting of three unciliated monokinetids. However, the species is larger than other Askenasia with a single distinctive, rope-like, scalloped macronucleus. This species also appears to have an extra somatic kinety belt, which may be present but has not been observed in other Askenasia species. Based on size, kinety structure, kinety number, and macronuclear shape a new species has been established.     

锦葵科植物DNA条形码通用序列的筛选

对锦葵科植物样品的ITS、ITS2、rbcL、matK和psbA-trnH序列进行PCR扩增和测序, 比较各序列的扩增效率、测序成功率、种内和种间变异的差异以及barcoding gap图, 使用BLAST1和Nearest Distance方法评价不同序列的鉴定能力, 进而从这些候选序列中筛选出较适合锦葵科植物鉴别的DNA条形码序列。结果表明, ITS序列在采集的锦葵科植物11个种26个样品中的扩增成功率较高, 其种内、种间变异差异和barcoding gap较ITS2、psbA-trnH及rbcL序列具有更明显的优势, 且纳入60个属316个种共1 228个样品的网上数据后, 其鉴定成功率可达89.9%。psbA-trnH序列的扩增和测序成功率最高, 其鉴定成功率为63.2%, 并能鉴别一些ITS序列无法鉴别的种。实验结果表明, ITS和psbA-trnH是较适合鉴别锦葵科植物的DNA条形码序列组合。     

PORPHYRA REDIVIVA SP. NOV. (RHODOPHYTA): A NEW SPECIES FROM NORTHEAST PACIFIC SALT MARSHES1

A new species, Porphyra rediviva (Bangiales, Rhodophyta), is described from the northeast Pacific based on morphological, cytological, reproductive, ecological, and molecular characters. This species occurs at high intertidal levels in salt marshes along the coasts of Washington, Oregon, and northern California and exhibits a growth optimum at reduced salinity. It is further distinguished by a distinct demarcation between male and female sectors of the gametophytic thalli of epilithic specimens. The species is found most commonly in the drift or trapped in Salicornia beds, but these detached blades never have been found with sporangia or gametangia. Molecular analyses using restriction fragment length polymorphism patterns of polymerase chain reaction–amplified ribosomal DNA (rDNA) show that this salt marsh Porphyra is conspecific throughout its range and is distinct from other Pacific Porphyra species with similar reproductive patterns. Based on molecular data, P. rediviva is related most closely to P. purpurea from the North Atlantic. Fixed rDNA polymorphisms between the two taxa, however, support ecological and cytological evidence that they should be considered different species.     

Pseudocyphellaria crocata, P. neglecta and P. perpetua from the Northern and Southern Hemispheres are a phylogenetic species and share cyanobionts

Pseudocyphellaria crocata, P. neglecta and P. perpetua specimens were examined to investigate links between genetic variation and morphology, geographical distribution and cyanobiont specificity. Fungal internal transcribed spacer (ITS), beta-tubulin and cyanobacterial tRNA(Leu) (UAA) intron sequences were used to investigate symbiont diversity in these lichens. Specimens were morphologically distinct but could not be distinguished by ITS sequences. Phylogenetic analyses split the P. crocata specimens into two clades, the larger of which contained P. neglecta and P. perpetua. Five cyanobionts were identified; two of these were in a number of specimens, while three were each restricted to a single lichen thallus. Fungus-specific molecular markers indicated that all specimens belonged to a single phylogenetic species. However, this may contain a cryptic species. Geography was linked to genetic diversity with Canadian specimens forming a monophyletic group, and most Southern Hemisphere specimens grouping together, although Chile represented a hot spot of genetic diversity. There was no connection between fungal genetic diversity and cyanobiont choice, consistent with the presence of a common pool of cyanobionts.     

Distribution, reproduction and feeding of the Greenland shark Somniosus (Somniosus) microcephalus, with notes on two other sleeper sharks, Somniosus (Somniosus) pacificus and Somniosus (Somniosus) antarcticus

The size and depth distribution, stomach contents and reproductive status of Somniosus ( Somniosus ) microcephalus, Somniosus ( Somniosus ) pacificus and Somniosus ( Somniosus ) antarcticus were examined from specimens collected from the North and South Atlantic, North and South Pacific, and the Southern Ocean. Specimens ranged in size from 42 to 480 cm total length, L _T, and were taken from depths of 35–1280 m. Stomach contents included coelenterates, gastropods, cephalopods, echinoderms, crustaceans, elasmobranchs, teleosts, penguins, marine mammals and human waste. Female S. ( S. ) microcephalus mature at c . 450 cm and S. ( S. ) antarcticus at c . 435 cm L _T; a female S. ( S. ) pacificus of 430 cm was mature. Male S. ( S. ) microcephalus mature at c . 300 cm, but male S. ( S. ) antarcticus may not mature until c . 400 cm L _T. The size at birth in these three species of Somniosus is c . 40 cm L _T.