Observations on the ciliary feeding mechanism of the brachiopod Crania anomala

In young Crania anomala with a trocholophe or an early schizolophe one inhalant current enters the anterior gape, filters past the single bell-shaped cirrous basket and spills out diffusely as exhalant current both anteriorly and laterally. Late schizolophe or early spirolophe forms two separate cirrous baskets which produce two separate inhalant currents: the exhalant current still diffuses out anteriorly and laterally. In later stages either one single exhalant current comes out at the anteromedial region, or three exhalant currents, including an additional one at each posterolateral region.
The roof of the visceral cavity is attached in five places to the dorsal valve of Crania to form a mantle recess, an anterior passage and two lateral passages. A hole bored through the dorsal valve into the mantle recess or the anterior passage lets out exhalant current. The palaeobiological significance of this lies in the possible use of the hole in the perforate shell valve of the siphonotretid fossil inarticulate Schizambon australis as an exhalant opening. In this species the hole leads into the mantle recess, which also communicates via a lateral passage with each posterolateral part of the mantle space.     

Lingulichnites, a new trace fossil genus for lingulid brachiopod burrows

Holocene lingulid brachiopods are well-known burrowing organisms. Fossil lingulid burrows have been reported from rocks in Europe and North America that range from Ordovician and Devonian through Pennsylvanian. However, the latest authoritative compendium on trace fossils, The Treatise on Invertebrate Paleontology (1975). makes no mention of lingulid burrows. The obvious reason for this omission is that the burrows, although important paleontologically and ichnologically, have never been named formally thereby making it awkward to include them in faunal lists. The monotypic genus Lingulichnites is proposed to remedy this problem. The type specimens are from Upper Devonian rocks in northeastern Ohio.     

Discussion of the Early Devonian rhynchonellid brachiopod genus Borealirhynchia Su, 1976

The Early Devonian brachiopod genus Borealirhynchia was established by Su, 1976. Phylum Brachiopoda (Cambrian to Devonian). In: Paleontological Atlas of North China, Inner Mongolia Volume 1. Geological Publishing House Beijing, pp. 155-227 (in Chinese). It has not been previously described in detail, nor have transverse serial sections of the internal features of Borealirhynchia delerensis, the type species, been published. In this paper Borealirhynchia, along with a few species previously assigned to it, is analysed and discussed. Detailed transverse serial sections of the internal features of B.? lata Su, 1976, are provided, based on well-preserved specimens collected from the Lower Devonian strata of Dong Ujimqin Qi, northeastern Inner Mongolia. Borealirhynchia? gigantea Su, 1976 and Latonotoechia multicosta Su, 1976 are considered to be synonyms of B.? lata Su with the same external and internal characters present in all three species. Some Lower Devonian strata, in which Borealirhynchia was found and reported, from Dong Ujimqin Qi, northeastern Inner Mongolia, are fully described.     

Molecular systematics, biogeography and population structure of neotropical freshwater needlefishes of the genus Potamorrhaphis

Phylogenetic relationships of populations and species within Potamorrhaphis, a genus of freshwater South American needlefishes, were assessed using mitochondrial cytochrome b sequences. Samples were obtained from eight widely distributed localities in the Amazon and Orinoco rivers, and represented all three currently recognized species of Potamorrhaphis. The phylogeny of haplotypes corresponded imperfectly to current morphological species identities: haplotypes from P. guianensis, the most widespread species, did not make up a monophyletic clade. Geography played a strong role in structuring genetic variation: no haplotypes were shared between any localities, indicating restricted gene flow. Possible causes of this pattern include limited dispersal and the effects of current and past geographical barriers. The haplotype phylogeny also showed a complex relationship between fishes from different river basins. Based on the geographical distribution of clades, we hypothesize a connection between the middle Orinoco and Amazon via rivers of the Guianas. More ancient divergence events may have resulted from Miocene alterations of river drainage patterns. We also present limited data for two other Neotropical freshwater needlefish genera: Belonion and Pseudotylosurus. Pseudotylosurus showed evidence of substantial gene flow between distant localities, indicating ecological differences from Potamorrhaphis.     

Age and distribution of the Late Devonian brachiopod genus Dzieduszyckia Siemiradzki, 1909 in southern China

Conodont biostratigraphical work was done at four sections recently found with occurrence of the rhynchonellide brachiopod genus, Dzieduszyckia Siemiradzki, in southern Guangxi and in the border area between Dushan County of Guizhou and Nandan County of Guangxi, South China. These sections represent two different types of facies, i.e., carbonate platform and intraplatform basin. The conodont analysis reveals that this genus occurs in the Upper triangularis Zone and the Middle crepida Zone at the Dazhai Section, through the Lower to Upper crepida zones at Dalong, and is restricted within the Upper rhomboidea Zone at the two intraplatform basin sections (Changtang and Duli). This result demonstrates that the occurrence of these peculiar rhynchonellide brachiopods in South China, regardless of the depositional environments, is within the Lower Famennian instead of the previously suggested Upper Famennian. Furthermore, this brachiopod genus in South China began to inhabit on the carbonate platform almost since the beginning of the Famennian and did not extend to the intraplatform basin facies until the late Early Famennian.Available biostratigraphic data indicate that during the Early and Middle Famennian, Dzieduszyckia is widely distributed not only in South China, but also throughout the world, such as Morocco and southern Ural.Observation on the new collections from the four studied sections reveals that the peculiar rhynchonellide brachiopods have a great morphological variation within each section. Significant differences existed among the collections from different sedimentary settings and localities, probably reflecting the environmental and geographic constraint on the morphology of Dzieduszyckia. Samples from different layers in the same section have nearly identical morphological variation, suggesting the temporal inheritance in morphology of the rhynchonellide brachiopod.     

中华真地鳖低龄若虫消化道结构及取食习性

解剖喂食不同饲料中华真地鳖EupolyphagasinensisWalker的低龄若虫 ,结果表明 ,低龄若虫消化道与成虫消化道结构相同 ,具有胃盲囊和马氏管 ;嗉囊、中肠和后肠分别占消化道总长的比率与中龄若虫相同 ,具有消化食物的能力。观察消化道各部分的滞留物变化情况 ,发现 1龄若虫取食了饲养土中的腐殖质和配合饲料 ,表明孵化后的若虫需要喂食以满足营养需要。     

Cyrtinoides Yudina and Rzhonsnitskaya, 1985, an aberrant Middle Devonian ambocoeliid brachiopod genus from China

Here we redescribe and reillustrate specimens of an ambocoeliid brachiopod previously described as Echinocoelia guangsiensis Sun, 1992 from the late Eifelian–earliest Givetian Mingtang Formation of the Liujing section in Guangxi Autonomous Region. The internal structure of the species, and especially the presence of a spondylium with tichorhinum in the ventral valve indicates that the species represents the aberrant genus Cyrtinoides Yudina and Rzhonsnitskaya, 1985. It seems probable that the anterior part of the tichorhinum in Cyrtinoides accommodated the diductor attachments. Geographic distribution of Cyrtinoides is restricted to the Northern Hemisphere and shows a disjunct pattern. This genus has not hitherto been identified from China.     

Life history variation between species of the relictual genus Borderea (Dioscoreaceae): phylogeography, genetic diversity, and population genetic structure assessed by RAPD markers

The genus Borderea consists of two species, B. pyrenaica and B. chouardii, taxa which have been previously considered as conspecific due to their overall close morphology. These two sole species of the rare genus of Dioscoreaceae are endemic to the Pyrenees (Spain, France). This mountain range likely operated as a refugium for these plants during the last glaciations. B. chouardii is only known from a single population in the Spanish Prepyrenees and has been classified as at risk of extinction in the Red List of Endangered Species (IUCN); B. pyrenaica shows a narrow distribution range in the central Pyrenees and Prepyrenees. We analysed genetic variation, population structure and differentiation in these two taxa using RAPD markers. Our study was conducted on the same seven populations for which very low levels of genetic differentiation were detected previously through allozyme analysis. By contrast, high levels of genetic variability were detected through the RAPD hypervariable markers. Twelve RAPD primers produced 112 distinct bands in the 397 surveyed individuals, totalling 395 different RAPD phenotypes. Only four bands were monomorphic across all samples of Borderea, whereas 21 of the polymorphic bands were species‐specific (20 for B. chouardii, and one for B. pyrenaica). The largest genetic distances were those between the B. chouardii and the B. pyrenaica phenotypes. An analysis of molecular variance showed greater variance between groups (B. chouardii vs. B. pyrenaica, 76.08%) than within groups (3.60%). RAPD band specificity, phenotypic distances, and the partitioning of variance all support the taxonomic separation of the two species. Statistical evaluation of within‐ and among‐population RAPD genetic variability in B. pyrenaica showed that genetic variability was higher within populations (>80%) than among them. No clear pattern of RAPD differentiation could be observed among the six studied populations of this taxon though slight differences in genetic diversity could be observed in the more isolated Prepyrenean populations compared with the more widespread Pyrenean ones. These results suggest a recent postglacial origin of the present B. pyrenaica populations. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80 , 483–498.     

First Occurrence of the brachiopod family Erymnariidae Cooper in the Upper Cretaceous of southern Italy

The rhynchonellid family Erymnariidae Cooper includes the new genus Costerymnaria together with Erymnaria Cooper, which comprises all the known erymnariids, and Erymnaria matensis (Capasso) from the Cenomanian of the Matese Mountains in southern Italy, which is revised herein. Costerymnaria includes three new forms: Costerymnaria italica sp. nov. and Costerymnaria sp. from the Cenomanian of the Matese Mountains, and Costerymnaria apula sp. nov. from the uppermost Campanian of the Salentine Peninsula, also in southern Italy. The shell ultrastructure and mode of life together with the taphonomy of these taxa are discussed. The occurrence of these rhynchonellids extends the stratigraphical range of the family Erymnariidae, its first appearance being in the Cenomanian, and also its geographical distribution to include the southernmost part of Italy. The erymnariids are, therefore, typical Tethyan forms. Erymnaria is one of the few brachiopods to have survived the Cretaceous-Paleogene boundary events. Along with Costerymnaria it probably developed in parallel from a common ancestral stock during the Late Cretaceous.     

Shell structure,ornamentation and affinity of the problematic early Cambrian brachiopod Heliomedusa orienta

The origin of the Brachiopoda has long been a hotly debated topic, and various models have been proposed following the latest finds of exceptionally preserved material. The lower Cambrian (Stage 3) Heliomedusa orienta from the Chengjiang Konservat-Lagerstätte, eastern Yunnan of South China, is an important example of exceptional preservation. A wide variety of affinities have been proposed for Heliomedusa, but recently it has been suggested to reside within the mickwitziids, which may form a stem group to the Brachiopoda. Detailed studies of exceptionally preserved Heliomedusa have increased our knowledge of the soft-part anatomy of this important early brachiopod, but unfortunately, almost nothing is known about its shell structure. Here, we describe new exceptionally preserved specimens from the Chengjiang biota to better reveal both shell structure and ornamentation. Its reticulate–pustulose ornament and tubular structure are reminiscent of traits seen in other mickwitziid brachiopods. In addition, two types of setae can be observed. Apart from the pyritized marginal mantle setae, some tubules are filled with iron oxides, potentially representing thinner and shorter penetrative setae. Both valves of H. orienta appear to have been less mineralized as compared to Mickwitzia monilifera, and the two species differ in diameter and density of tubules and pustules, and in terms of slightly less projected profile of ventral valve with lower umbo posteromedially placed. Although Heliomedusa clearly is closely related to Mickwitzia, their different preservational modes (compacted poorly mineralized/noncompacted mineralized) make detailed comparison difficult; they are provisionally kept as separate genera pending further studies of better-preserved Chinese material.     

Egg energetics, fertilization kinetics, and population structure in echinoids with facultatively feeding larvae

Larvae of marine invertebrates either arise from small eggs and feed during their development or arise from large eggs that proceed to metamorphosis sustained only from maternal provisioning. Only a few species are known to possess facultatively feeding larvae. Of about 250 echinoid species with known mode of development, only two, Brisaster latifrons and Clypeaster rosaceus, are known to develop through facultatively planktotrophic larvae. To obtain more information on this form of development and its consequences, we determined egg size and egg energetic and protein content of these two species. We found that eggs of B. latifrons resemble those of species with nonfeeding larvae in these characteristics more than those of C. rosaceus. We also compared DNA sequences of the cytochrome oxidase (COI) gene from the Caribbean C. rosaceus to those of the sympatric planktotrophic developer C. subdepressus and also to those of the eastern Pacific species C. europacificus to estimate the degree of divergence between species with different developmental modes. Comparison of COI sequences of C. rosaceus from Panama and Florida revealed that there is no geographic differentiation in this species. Cross-fertilization experiments between C. rosaceus and C. subdepressus indicated that bidirectional gametic incompatibility has evolved between the two species.     

Cephalopod and brachiopod fossils from the Pacific: Evidence from the Upper Cretaceous of the Magellan Seamounts

Maastrichtian cephalopods and a brachiopod were dredged from the Butakov, Fedorov, Kotsebu, Il’ichev, Govorov, Gelendzhik, and Ita-Mai-Tai guyots in the Magellan Seamounts. The ammonoids Hypophylloceras sp., Phyllopachiceras sp., Anagaudryceras? sp. A, Anagaudryceras? sp. B, Gaudryceras aff. propemite Marshall, Gaudryceras sp., and Pseudophyllites cf. indra (Forbes), and the single brachiopod Basiliolidae gen. and sp. indet. are a first discovery in this oceanic region, following earlier finds of belemnites (Dimitobelus? sp., Dimitobelidae gen. and sp. nov., and Belemnitella? sp.), and two ammonoid species (Zelandites aff. japonicus Matsumoto and Tetragonitidae gen. and sp. indet.). The Late Cretaceous Magellan Seamounts dimitobelid belemnite fauna shows affinities with southern high latitude forms (New Zealand) and the ammonoid fauna with northern, middle and high latitude ones (Hokkaido-Sakhalin and/or Kamchatka). This suggests by the end of the Cretaceous major surface palaeo-currents from S and N sides in direction of the central Palaeo-Pacific, a position coinciding with the plate tectonic reconstruction of the Magellan Seamounts.     

Growth rate and substrate-related mortality of a benthic brachiopod population

Collins, M. 1991 01 15: Growth rate and substrate-related mortality of a benthic brachiopod population. Lethaia , Vol. 24, pp. 1–11. Oslo. ISSN 0024–1164.
Vital staining and careful examination of potential substrates enabled an accurate census of Terebratulina retusa to be made and prompted a study of their population dynamics. Seasonal samples of T. retusa from a deep water Modiolus -brachiopod assemblage were always dominated by small (>1 mm) individuals as growth rate of the post-larvae, estimated from changes in mean cohort length. was unexpectedly slow. Six months after settlement the animals had barely doubled in length, a rate of increase consistent with laboratory studies, but an order of magnitude less than conventional estimates. As the attainment of a size refuge is the only documented strategy by which articulate brachiopods counter overgrowth or disturbance this observation has profound implications for survival. Mortality of T. retusa in the Firth of Lorn, from different substrates, followed an unexpected pattern. Virtually the only substrate on which adult T. rehusa were recorded was the surface of M. modiolus shells, although juvenile T. retusa attached to this substrate suffered enhanced levels of mortality. Grazing pressures and spatial competition, believed to be reduced on complex surfaces, may account for the elevated mortality levels of M. modiolus-attached post-larvae prior to the apparent size refuge at a length of 2 mm. * Brachiopoda, Terebratulina, growth rate, disturbance, ecology, population structure .     

The genus Luppovia and the phylogeny of Cretaceous heteromorphic ammonoids

The unique preservation of heteromorphic shells of Luppovia Kakabadze, Bogdanova & Mikhailova 1978 from the Aptian deposits of Bolshoj Balkhan (western Turkmenia) made it possible to study the microstructure, internal shell characteristics and suture ontogeny of this genus. Microstructural investigations revealed that the dorsal shell wall in Luppovia is composed of three layers in contrast to that of monomorphic ammonoids, which is single-layered. This ability of secreting different numbers of layers in monomorphs and heteromorphs demonstrates plasticity of secreting activity of the mantle epithelium. Data obtained from the study of internal shell structure and suture ontogeny have been compared. Both these methods of investigation lead to the conclusion that the genus Luppovia belongs to the order Ammonitida. The results obtained confirm the viewpoint that the Cretaceous heteromorphic superfamilies Turrilitaceae and Ancylocerataceae have independent origins and belong to two different orders, Lytoceratida and Ammonitida, respectively. □ Ammonoidea , Luppovia, shell structure, ontogeny, phylogeny, Cretaceous.     

Shell structure and affinities of the enigmatic Lower Ordovician articulate brachiopod Lycophoria Lahusen, 1886

Wright, A. D. 1992 04 15: Shell structure and affinities of the enigmatic Lower Ordovician articulate brachiopod Lycophoria Lahusen. 1886. Lethaia . Vol. 25, pp. 125–129. Oslo. ISSN 0024–1164.
The enigmatic Baltoscandian Lower Ordovician brachiopod Lycophoriu has a combination of morphological characters that makes it difficult to place taxonomically. The more recent assignments of the genus have been with the Porambonitacea, the Triplesiacea and the Orthacea. A basic character in articulate brachiopods is the differentiation of the secondary shell into either stacked fibres or laminar sheets. The hitherto unknown shell structure in Lycophoria has been examined under the electron microscope and is shown to be fibrous, which is taken as ruling out any close affinity with the lamellar shelled Triplesiacea. Despite superficial similarities, features of the shell interior are not compatible with the pentameride Porambonitacea and although there are differences from the typical orthacean, these are no greater than those of the accepted orthid Producrorrhis. Lycophoria , in the monotypic family Lycophoriidae, is accordingly best regarded as a specialized offshoot of the basic orthacean stock. * Shell microstructure, Lycophoridae, Orrhacea, Porambonitacea, Triplesiacea, Lower Ordovician, Baltoscandia .     

New species and biostratigraphic significance of middle Palaeozoic brachiopod genus Linguopugnoides Havliček

Linguopugnoides Havli?ek 1960, originally based on 3 Early Devonian (Lochkovian‐Pragian) species from the Czech Republic, is now construed as embracing at least 25 species distributed over all northern hemisphere continents as well as Australia, and extending from late Llandovery to early Emsian. Species‐diversity peaked during the Lochkovian when the genus was widespread, with 15 species having been reported. Four species are described as new. L. praecarens sp.nov. from the latest Silurian (Pridoli) of the Turkestan Range (South Tien Shan) is considered to be ancestral to the numerous, mainly late Lochkovian‐Pragian forms that appeared during the great diversification of the genus during the early Devonian. Three new species are described from the Lochkovian of the Zeravshan Range, Uzbekistan: L. rectiplicatus, L. diversiplicatus as well as the previously figured but not described L. kimi Rzhonsnitskaya. Species of Linguopugnoides have biostratigraphic and biogeographic significance and have obvious value for inter‐regional correlation.     

Disturbance and contrasting patterns of population structure in the brachiopod Terebratulina septentrionalis (Couthouy) from two subtidal habitats

The population structures of Terebratulina septentrionalis (Couthouy) from exposed upper rock surface and semi-cryptic rock wall habitats at 33 m depth in the Gulf of Maine differ. Over a 3-yr period, population densities were consistently higher in rock wall habitats. Although both populations were dominated by juveniles (1–4 mm shell length), size-frequency distributions constructed from upper rock surface and rock wall populations were significantly different, as a result of a greater frequency of large brachiopods (> 20 mm shell length) in rock wall populations. Prominent modes occurred at 14–15 mm shell length in upper surface populations and at 19–20 mm length in rock wall populations. Recruitment was higher in rock wall habitats where ambient light intensities were significantly lower than on upper rock surfaces. Differences in recruitment are either the result of larval selection for shaded rock walls or differential juvenile mortality between habitats. The larvae of Terebratulina settle on a diverse array of substrata. These include bedrock, sandy polychaete tubes and algae in upper surface habitats and bedrock, calcareous polychaete tubes, and ascidians in rock wall habitats. Individuals attached to polychaete tubes and algae in upper surface habitats do not attain large body size (> 13 mm shell length). It is suggested that these differences in population structure reflect the greater intensity of disturbance in upper surface habitats. For example, the cod, Gadus morhua (Linnaeus), ingests brachiopods attached to algae and polychaete tubes in this habitat. Gastropod predation affects brachiopods in upper surface habitats but not in rock wall habitats. Predation by gastropods and asteroids is not size-specific. These results are consistent with the hypothesis that predation contributed to the decline in the abundance and diversity of articulate brachiopods since the Mesozoic, and suggest that the restriction of recent populations to semi-cryptic rock wall and crevice habitats is, in part, controlled by disturbance.     

Variable pedicle morphology in a population of the Recent brachiopod Terebratulina septentrionalis

Extremely variable pedicle morphology is described in a large sample of the Recent articulate brachiopod Terebratulina septentrionalis (Couthouy) from off the coast of Nova Scotia. The majority of these specimens were attached to the shells of living or dead scaphopods by a dense network of pedicle rootlets. Other brachiopods had been lying on the sea-floor anchored solely by the weight of sediment enmeshed within the bush-like network of pedicle rootlets. Some brachiopod larvae had settled on the exposed pedicle rootlets of adults, presumably because of the scarcity of other suitable substrate. Such a mode of life is thought 'to indicate that these brachiopods could survive a further reduction in the available substrate and it is suggested that, should such conditions persist, changes in hard-part morphology would enable descendants of the species to adopt a predominantly free-lying mode of life. Likely morphological adaptions are suggested, based on examples from the fossil record. This evolutionary trend, from attached to free-lying and perhaps vice versa, has occurred many times in the history of the Phylum Brachiopoda, and it is suggested that the mode of life of this T. septentrionalis population provides an important insight into at least one of the possible evolutionary pathways which bring about such transformations.     

Allozyme analyses of the genus Trisopterus: taxonomic status and population structure of the poor cod

Genetic analysis of the four Trisopterus (Gadidae) taxa suggests that the interrelationships of the two morphs of poor cod ( T. minutus minutus in the Atlantic and T. minutus capelanus in the Mediterranean) should be reconsidered. The Mediterranean poor cod T. m. capelanus is more closely related to bib T. luscus than to the Atlantic poor cod, so the population structure in the Atlantic and Mediterranean poor cod must be considered separately. Among 635 Atlantic individuals there was some evidence of poor cod population differentiation (allele frequency heterogeneity test P <0·0005; F _ST=0·0135, P ≤0·0005). Levels of genetic variation were similar to those reported for related gadoid species. Some differentiation was present on the Norwegian coast (samples from Trondheimsfjord) and between the Faeroe Islands (Faeroe Bank) and the adjacent European coastal location. In contrast no statistically significant population differentiation was evident in Mediterranean poor cod, but fewer samples and individuals were screened.