Arachnids from the Carboniferous of Russia and Ukraine,and the Permian of Kazakhstan

New finds of Late Palaeozoic arachnids, based on three well-preserved carapaces from the Carboniferous of Russia and Ukraine and one complete, albeit poorly preserved, specimen from the Permian of Kazakhstan, are described. The spider genus Arthrolycosa is reported from the Late Carboniferous (Late Pennsylvanian: Kasimovian–Gzhelian) of Chunya in the Tunguska Basin of Siberia; it is the first find of a spider outside the Carboniferous tropics. Another fossil assigned to the same genus comes from the Late Carboniferous (Early Pennsylvanian: Bashkirian) of Kamensk–Shakhtinsky in the Donets Basin of Russia; it is probably the oldest fossil spider known. A thelyphonid (whip scorpion) carapace is described from the Late Carboniferous (Late Pennsylvanian: Kasimovian) of the adjacent Lugansk Province of the Donets Basin of Ukraine.     

Three new species of Loxosoma (Entoprocta) from Phuket, Thailand, with a review of the genus

Three new species of Loxosoma are described, L. nung and L. song , on the polychaete Pectinaria brevispinis from the reef flat in front of Phuket Marine Biological Center, and L. sum on the polychaete Axiothella obockiensis from a sand flat at Nai Yang Beach, Phuket Island. The genus Loxosoma is briefly reviewed. Species originally referred to Loxosoma but now transferred to Loxosomella are listed; insufficiently characterized species probably belonging to Loxosomella are listed as well. The monospecific genus Loxostemma is synonymized with Loxosoma . The subgenus name Loxosomina is proposed to replace the junior homonym Loxomorpha .     

Enigmatic polychaete jaws from the Silurian of Gotland, Sweden

The jaws of the new polychaetaspid polychaete, Oenonites? honki, from the Silurian of Gotland, Sweden, differ from most Palaeozoic polychaete jaws. They exhibit enigmatic microstructural features in that they appear rough and give a corroded, or weathered impression. The altered microstructure of the jaws suggests a jaw chemistry and/or composition differing in some way from that of the co‐occurring polychaete taxa. The jaws appear to have limited preservational potential and/or were particularly susceptible to secondary processes, resulting in microstructural alteration. Commonly, a row of distinct pits occurs on the outer face, especially of the first right maxillae (MIr). Because these pits are interpreted as associated with the dentary, the term ‘denticle marks’ is suggested. The pits may be the result of primary or secondary physical wear, or, more probably, secondary chemical alteration of localized mineral deposits. The primary function of such mineral deposits was to harden those parts of the surface that were exposed to great stress. The restricted occurrence of O.? honki, coupled with occasional increases in abundance (especially in the Halla Formation, unit b), indicates a preference for shallow marine, high‐energy environments, particularly in reefal pockets with calcilutitic sediments. Highest frequency coincides with faunas characteristically containing a few labidognath species also displaying high frequencies.     

Formation and diagenesis of Visean trace fossils from Ireland

Tube-like trace fossils occur within dolomitised Visean pelmicrites in County Fermanagh, Northern Ireland. The pelmicrites are associated with algal laminated carbonates and evaporites which imply deposition in a coastal sabkha. The tubes exhibit a preferred orientation caused by minor current systems. Thin sections and scanning electron micrographs show that in life the tubes were characteristically bilaminar, with an internal sheath of organic material and an organically cemented tube wall. This structure resembles that of modern polychaete worms. Comparison with a Bahaman polychaete suggests that the Visean worms inhabited a subtidal algal mat. The diagenetic history of the tubes is one of progressive dolomitisation and is closely linked to the presence of organic substances in the walls of the tubes and the mucus sheath which lined the tubes during the worm's life. The presence of the organic matter may have been a prerequisite for the formation of the dolomite observed in the tubes. Ichnofossils, diagenesis, dolomitisation, sabkha environment, Polychaeta, algal mats. Carboniferous, Visean, Northern Ireland, Fermanagh.     

Late Paleozoic faunal, climatic, and geographic changes in the Baoshan block as a Gondwana-derived continental fragment in southwest China

The Carboniferous and Permian of the Baoshan block consist of three major depositional sequences: a Lower Carboniferous carbonate sequence, a Lower Permian siliciclastic sequence, and a Middle Permian carbonate sequence. These three sequences were interrupted by two major regressive events: first, the Namurian Uplift ranging in age from Serpukovian to Gzhelian, and second, the Post-Sakmarian Regression occurring probably at Artinskian time in the Baoshan block, although the precise time interval of the latter event is still unclear. The Baoshan block is characterized by warm-water, highly diverse and abundant faunas during the Early Carboniferous, by cold-water and low diversity faunas during the Early Permian, and by possibly warm-water but low diversity faunas during the Middle Permian. The Sweetognathus bucaramangus conodont fauna constrains the upper boundary of the diamictite-bearing siliciclastic deposits (Dingjiazhai Formation) to the Sakmarian to early Artinskian, as well as the eruption of the rifting basalts (Woniusi Formation) to, at least, the post-early Artinskian. Paleozoogeographically, affiliation of the faunas in the Baoshan block changed from Eurasian in the Early Carboniferous, to Peri-Gondwanan in the Early Permian, and to Marginal Cathaysian/Cimmerian in the Middle Permian. Cimmerian blocks have more or less comparable geohistory to one another in the Carboniferous and Permian. During the Middle Permian, the eastern Cimmerian blocks such as Sibumasu (s.s), Baoshan, and Tengchong are not far from the palaeoequator, but apparently more distant than the western Cimmerian blocks based on the presence or absence of some index taxa such as the fusulinaceans Eopolydiexodina and Neoschwagerina, and the corals Thomasiphyllum and Wentzellophyllum persicum.     

Posidonia becheri Bronn, 1828 from the Tournaisian of SE Turkey: A palaeobiogeographic enigma

The posidoniform bivalve species Posidonia becheri Bronn, 1828, has been identified for the first time in the Lower Carboniferous (Tournaisian) sandy limestone-dark grey shale deposits of Hakkari Province, south-eastern Turkey. Palaeogeographically, this area was located at the northern tip of the Gondwanan Arabian Palaeozoic platform at the southern Palaeotethyan margin during the Carboniferous. The closest localities to this new occurrence are the Lower Carboniferous of northern England, Germany (Kulm Basin), Poland (Walbrzych Basin), Northwest Belgium, Spain (Cantabrian Mountains), Portugal, and Northwest Turkey (Zonguldak Basin). All these locations are considered parts of the Avalonian or Perigondwanan terranes, and were located NW of the Palaeotethys. Hence, our new finding from the SE Palaeotethyan margin, together with the data from Morocco, indicates that this posidoniid bivalve had probably been transported by oceanic currents in its larval stage to lower palaeolatitudes (about 50° S) within the Palaeotethyan Ocean during the Early Carboniferous, or alternatively, the northern Arabian platform margin was located in lower latitudes than previously suggested.     

Commensal symbiosis between agglutinated polychaetes and sulfate‐reducing bacteria

Pendant bioconstructions occur within submerged caves in the Plemmirio Marine Protected Area in SE Sicily, Italy. These rigid structures, here termed biostalactites, were synsedimentarily lithified by clotted‐peloidal microbial carbonate that has a high bacterial lipid biomarker content with abundant compounds derived from sulfate‐reducing bacteria. The main framework builders are polychaete serpulid worms, mainly Protula with subordinate Semivermilia and Josephella. These polychaetes have lamellar and/or fibrillar wall structure. In contrast, small agglutinated terebellid tubes, which are a minor component of the biostalactites, are discontinuous and irregular with a peloidal micritic microfabric. The peloids, formed by bacterial sulfate reduction, appear to have been utilized by terebellids to construct tubes in an environment where other particulate sediment is scarce. We suggest that the bacteria obtained food from the worms in the form of fecal material and/or from the decaying tissue of surrounding organisms and that the worms obtained peloidal micrite with which to construct their tubes, either as grains and/or as tube encompassing biofilm. Peloidal worm tubes have rarely been reported in the recent but closely resemble examples in the geological record that extend back at least to the early Carboniferous. This suggests a long‐lived commensal relationship between some polychaete worms and heterotrophic, especially sulfate‐reducing, bacteria.     

The earliest evidence of damselfly‐like endophytic oviposition in the fossil record

The reproductive strategy of insects of inserting eggs into plant tissue (endophytic oviposition) is known from the Late Carboniferous onwards. The earliest known ovipositional scars are large, that is up to 38 mm long, and irregular both in size and in shape, and they are not arranged in a regular pattern. Oviposition patterns resembling those of present‐day Odonata are first reported from the Late Palaeozoic. These egg cavities are generally of smaller size and have a regular oval shape. They are usually arranged in longitudinal rows or in a zigzag configuration. The most likely tracemakers were gracile damselfly‐like insects such as the Archizygoptera, a group closely related to modern Zygoptera. In this paper, the earliest evidence of endophytic oviposition resembling the ‘Coenagrionid Type’ of Odonatoptera is described. It derives from the Wettin member of the Siebigerode Formation of the Saale‐Basin in Central Germany (Upper Carboniferous, Gzhelian) and consists of about 49 elliptical scars with lengths of about 2 mm, probably deposited on a leaf of Cordaites. The arrangement of the scars in short transverse rows, their regular size and elliptical shape suggest that the tracemaker was probably a member of the extinct odonatopteran suborder Archizygoptera. If so, the tracefossil described here would be the earliest evidence for this endophytic oviposition in an ancestral group of modern Zygoptera.     

Decline in diversity of early Palaeozoic loosely coiled gastropod protoconchs

Quantitative data on molluscan larval conch fossil assemblages of ages ranging from the Ordovician (Argentina and the Baltic region), through Silurian (Austria), Devonian (Poland) to Carboniferous (Texas) supplement knowledge of early planktonic gastropods communities transformations. They show that larval shells of the bilaterally symmetrical bellerophontids and dextrally coiled gastropods with a hook-like straight apical portion of the first whorl initially dominated. Their relative frequency, as well as that of the sinistrally coiled ‘paragastropods’, diminished during the Ordovician and Silurian to virtually disappear in the Late Devonian and Early Carboniferous. Already during the Ordovician, diversity of larvae with gently loosely coiled first whorl increased, to be replaced then with more and more tightly coiled forms. Both the aperture constrictions and mortality peaks, probably connected with hatching and metamorphosis, indicate that the Ordovician protoconchs with hook-like first coil represent both the stage of an embryo developing within the egg envelope and a planktonic larva. The similarity of the straight apex to larval conchs of hyoliths and advanced thecosome pteropods is superficial, as these were not homologous stages in early development.     

山东南部太原组一种新的具解剖构造的鳞木目茎--Diaphorodendron rhombicum sp.nov.

报道了产于山东枣庄矿区太原组16号煤层煤核(早二叠世早期或晚石炭世晚期)中一种具解剖构造的鳞木目茎.茎呈压扁状,长轴约6 cm,短轴约2.5 cm.中柱、外部皮层、周皮和叶座均保存.茎具原生中柱,无次生木质部发育,外部皮层由较发育的径向的厚壁的细胞条带和已经毁坏的薄壁的细胞区域交替排列构成.周皮较发育,厚约4～5 mm,由木栓层和栓内层构成.其中栓内层较厚,细胞构造均一,或在有些地方分化为弦向的薄壁的细胞条带和l厚壁的细胞条带,二者交替排列.其中薄壁的细胞条带常保存不好而形成弦向的裂隙.叶座的高和宽近相等,呈近正菱形.叶痕盔形或双凸镜形,位于叶座上部,微微突出于叶座表面之上.叶座表面平坦,未见明显的中脊和横皱纹.叶迹在叶座内近水平状延伸,但在近叶座表面处略向上然后向外弯曲成不太明显的"S"形进入叶痕内.径切面上叶舌穴略向上斜伸,具一宽大的基部,其开口直接位于叶痕顶角处.叶舌大,宽卵球形,长轴达1.2 mm,短轴达1 mm.与目前已知的鳞木目几个属的茎比较,当前标本与Diaphorodendron属的茎最为接近,仅在叶座上有些不同,本文将其归入该属内.Diaphorodendron属目前共有3个种,全分布于欧美植物区晚石炭世中期(威斯法期),它们与当前标本区别明显,因此,将当前标本归入新种D.rhombicum内.本文是国内首次报道Diaphorodendron属在华夏植物区的存在.其高和宽近相等的叶座形态可能表明了一种进化的特征,这从其所在地层的地质时代(早二叠世早期或晚石炭世晚期)较欧美植物区的3个种(晚石炭世中期)较新这一事实得到支持.     

Geological history and phylogeny of Chelicerata

Chelicerata probably appeared during the Cambrian period. Their precise origins remain unclear, but may lie among the so-called great appendage arthropods. By the late Cambrian there is evidence for both Pycnogonida and Euchelicerata. Relationships between the principal euchelicerate lineages are unresolved, but Xiphosura, Eurypterida and Chasmataspidida (the last two extinct), are all known as body fossils from the Ordovician. The fourth group, Arachnida, was found monophyletic in most recent studies. Arachnids are known unequivocally from the Silurian (a putative Ordovician mite remains controversial), and the balance of evidence favours a common, terrestrial ancestor. Recent work recognises four principal arachnid clades: Stethostomata, Haplocnemata, Acaromorpha and Pantetrapulmonata, of which the pantetrapulmonates (spiders and their relatives) are probably the most robust grouping. Stethostomata includes Scorpiones (Silurian–Recent) and Opiliones (Devonian–Recent), while Haplocnemata includes Pseudoscorpiones (Devonian–Recent) and Solifugae (Carboniferous–Recent). Recent works increasingly favour diphyletic mite origins, whereby Acaromorpha comprises Actinotrichida (Devonian–Recent), Anactinotrichida (Cretaceous–Recent) and Ricinulei (Carboniferous–Recent). The positions of the Phalangiotarbida (Devonian–Permian) and Palpigradi (Neogene–Recent) are poorly resolved. Finally, Pantetrapulmonata includes the following groups (listed here in their most widely recovered phylogenetic sequence): Trigonotarbida (Silurian–Permian), Uraraneida (Devonian–Permian), Araneae (Carboniferous–Recent), Haptopoda (Carboniferous), Amblypygi (?Devonian–Recent), Thelyphonida (Carboniferous–Recent) and Schizomida (Paleogene–Recent).     

Polychaete worms--a vector for white spot syndrome virus (WSSV)

The present work provides the first evidence of polychaete worms as passive vectors of white spot syndrome virus (WSSV) in the transmission of white spot disease to Penaeus monodon broodstocks. The study was based on live polychaete worms, Marphysa spp., obtained from worm suppliers/worm fishers as well as samples collected from 8 stations on the northern coast of Tamilnadu (India). Tiger shrimp Penaeus monodon broodstock with undeveloped ovaries were experimentally infected with WSSV by feeding with polychaete worms exposed to WSSV. Fifty percent of polychaete worms obtained from worm suppliers were found to be WSSV positive by 2-step PCR, indicating high prevalence of WSSV in the live polychaetes used as broodstock feed by hatcheries in this area. Of 8 stations surveyed, 5 had WSSV positive worms with prevalence ranging from 16.7 to 75%. Polychaetes collected from areas near shrimp farms showed a higher level of contamination. Laboratory challenge experiments confirmed the field observations, and > 60% of worms exposed to WSSV inoculum were proved to be WSSV positive after a 7 d exposure. It was also confirmed that P. monodon broodstock could be infected with WSSV by feeding on WSSV contaminated polychaete worms. Though the present study indicates only a low level infectivity in wild polychaetes, laboratory experiments clearly indicated the possibility of WSSV transfer from the live feed to shrimp broodstock, suggesting that polychaete worms could play a role in the epizootiology of WSSV.     

Observation of large, non-covalent globin subassemblies in the approximately 3600 kDa hexagonal bilayer hemoglobins by electrospray ionization time-of-flight mass spectrometry

A non-covalent globin subassembly comprising 12 globin chains (204 to 214 kDa) was observed directly by electrospray ionization time-of-flight mass spectrometry in the native hexagonal bilayer hemoglobins from the oligochaetes Lumbricus terrestris and Tubifex tubifex, the polychaetes Tylorrhynchus heterochaetus, Arenicola marina, Amphitrite ornata and Alvinella pompejana, the leeches Macrobdella decora, Haemopis grandis and Nephelopsis oscura and the chlorocruorin from the polychaete Myxicola infundibulum, over the pH range 3.5-7.0. The Hb from the deep-sea polychaete Alvinella exhibited in addition, peaks at approximately 107 kDa and at approximately 285 kDa, which were assigned to subassemblies of six globin chains and of 12 globin chains with three non-globin linker chains, respectively. The experimental masses decreased slightly with increased de-clustering potential (60 to 160 V) and were generally 0.1 to 0.2 % higher than the calculated masses, due probably to complexation with cations and water molecules.     

Decay of Branchiostoma: implications for soft-tissue preservation in conodonts and other primitive chordates

Decay experiments on the cephalochordate Branchiostoma lanceolatum ('amphioxus') demonstrate that the most decay resistant structures are the notochord sheath and the cartilaginous rods which support the gill bars. However, even more labile soft parts, such as the muscles and skin may survive for at least 124 days under totally anoxic conditions. As the chevron-shaped muscles of the myomeres shrink and collapse, those on opposite sides of the trunk maybe displaced, resulting in pronounced offsetting. Only 1.42% of the initial dry weight of Branchiostoma is resistant to alkali and acid hydrolysis, compared to 46% in the polychaete Nereis virens. Branchiostoma is only likely to be fossilized as a result of decay inhibition and replication by early diagenetic minerals. The results of these experiments cast light on the interpretation of a number of primitive fossil chordates. There is no reason to infer extracellular decay-resistant cuticle in the Burgess Shale Pikaia. The axial lies preserved in the conodont animal specimens from the Carboniferous of Edinburgh, Scotland, represent the notochord. The displacement of the elements to one side of the head reflects the true position of the apparatus - the surrounding tissue has been lost through decay. The chevron-shaped structures in the Carboniferous chordate Conopiscius are the muscles of the myomeres, not external scales. The lines delineating the segments in the Silurian Jamoytius most likely represent the myosepta. There is some doubt about the nature of the only specimen interpreted as a fossil cephalochordate, Palaeobranchiostoma hamatotergum from the Permian of South Africa. □ Taphonomy, decay, softparts, Cephalochordata , Branchiostoma, lancelet, Chordata , Pikaia, conodont , Conopiscius, Jamoytius, Palaeobranchiostoma.     

Morphology, molecular data, and development of Zschokkella mugilis (Myxosporea, Bivalvulida) in a polychaete alternate host, Nereis diversicolor

The morphology of Zschokkella mugilis Sitjà-Bobadilla and Alvarez-Pellitero, 1993 (Myxosporea, Bivalvulida) in Nereis diversicolor O. F. Müller, 1776 is described for the first time. The molecular data show that the actinospore has 100% similarity to the myxospore of Z. mugilis. Fully mature actinospores are tri-radiate, the spore body has a small process, and the sporoplasm has 2 inner daughter cells. In the polychaete, the spores of the parasite develop in groups of 8 inside pansporocysts. The schizogony phase takes place in the intestinal epithelium, while gametogony and sporogony occur in the coelom of the polychaete. Observations indicate that mature spores are released only during the polychaete reproductive season. Infection was detected only in the winter and spring. In the Aveiro estuary (Portugal), the overall prevalence of infection of the polychaete was 0.5%.     

AGGREGATION BEHAVIOUR IN JUVENILE MILLIPEDES FROM THE UPPER CARBONIFEROUS OF MAZON CREEK, ILLINOIS

Abstract:  Two ironstone nodules are described from the Braidwood Biota of the Upper Carboniferous Mazon Creek Lagerstätte, Illinois, each preserving numerous juvenile millipedes referred to Euphoberia sp. The millipedes belong to different stadia, as evidenced by segment number, but are similar in size so probably nearly the same age. These juvenile euphoberiids differ from adults in having shorter pleurotergal spines, a reduced number of ocelli and a series of reduced, apodous trunk rings posteriorly. These nodules provide the first evidence of aggregation behaviour in Palaeozoic millipedes. Aggregation in juvenile euphoberiids is hypothesized to serve as a defence mechanism, compensating for the reduced length of their pleurotergal spines relative to adults, possibly through a collective chemical defence.     

Attached vermiform gastropods in Carboniferous marginal marine stromatolites and biostromes

Tubiform fossils conventionally referred to Serpula cf. advena Salter and species of Spirorbis Lamarck from the British Lower Limestone Shales and Border Group (Lower Carboniferous) are re-examined. They occur in peritidal carbonate environments of schizohaline aspect. These fossils superficially resemble calcareous polychaete tubes but have skeletal characters, including molluscan wall structure, numerous internal septa, and protoconch, which indicate that they represent a new group of substrate-attached, disjunctly coiled gastropods. They resemble archaeogastropods in internal morphology of the skeleton but show parallels in external form and occurrence with the extant Vermetidae. There are two principal modes of occurrence: (1) erect tubes forming intertidal biostromes associated with non-skeletal algal laminites, and (2) prostrate discoidal tubes encrusting subtidal skeletal stromatolites or occasionally forming larger irregular bioherms. These biostromes and bioherms are comparable in structure to Recent vermetid reef developments.     

Reproduction and larval development ofManayunkia aestuarina (Bourne, 1883) (Polychaeta,Sabellidae) in a coastal region of the southern Baltic

The reproduction and larval development ofManayunkia aestuarina, a polychaete typical of brackish lenitic waters, was studied in a tideless shallow region on the south Baltic coast in 1990. Reaching abundances of up to 50 000 ind./m², it is an important element of the benthic community in this area. Reproduction started in late March/early April, when the females deposited their eggs in the tubes. On the average, 4 (maximum: 16) developing embryos were found in a maternal tube during the reproduction period. The females probably produced a mean of about 12 eggs. Development in the maternal tube lasted about 8 weeks. The first juveniles were found outside the tubes in mid-May. The survival rate during the first few weeks was estimated to be 15–20%. After reproducing, the adult animals survived until October. The changes involved in the development from eggs to juvenile animals are illustrated by drawings.     

Early Carboniferous plants of the Arkhangelsk Region,Russia

Eight species of fossil plants are described for the first time from the Lower Carboniferous of the Arkhangelsk Region. One of these species, Adiantites lisitzynii O. Orlova et Jurina, is new. The taxonomic composition of the assemblage of 20 species indicates a woody vegetation of the Euramerian aspect. The rich assemblage recovered for the first time from terrigenous deposits of the Arkhangelsk Region dates them to the Visean (Early Carboniferous).     

Polychaete fauna associated with holdfasts of the large brown alga Himantothallus grandifolius in Admiralty Bay, King George Island, Antarctic

The polychaete community associated with holdfasts of the brown alga Himantothallus grandifolius in Admiralty Bay has been studied. It is the first study of its kind in this area and only the second in the Antarctic. Samples were collected in the summer season of 1979/1980 from a depth range of 10–75 m. Seventy-eight species were found on 19 holdfasts. The community was dominated by Brania rhopalophora and Neanthes kerguelensis. Analysis of similarity showed that polychaete fauna associated with this habitat did not show any partitioning related to depth. Regression analysis showed that densities of both species and individuals decreased with increased holdfast volume. A positive correlation was found between the number of individuals and holdfast volume. Polychaetes from 10 feeding guilds were found with dominance of macrophagous motile herbivores and sessile filter feeders. The complex habitat provided by holdfasts is a shelter for a rich polychaete fauna and may function as important protection from disturbance in the shallow areas of Admiralty Bay.