Study of the Trophi of <Emphasis Type="Italic">Testudinella</Emphasis> Bory de St. Vincent and <Emphasis Type="Italic">Pompholyx</Emphasis> Gosse (Rotifera: Testudinellidae) by Scanning Electron Microscopy

The fine morphology of the trophi of Pompholyx sulcata and nine species of Testudinella (Rotifera, Monogononta, Flosculariacea, Testudinellidae) was studied by scanning electron microscopy. The number of unci teeth and arched rami scleropili, and the shape of the major unci teeth and fulcrum are considered to be reliable additional characters for identification.     

A gentle method for the preparation of hard parts (trophi) of the mastax of rotifers and scanning electron microscopy of the trophi ofBrachionus plicatilis (Rotifera)

Summary Trophi of the rotiferBrachionus plicatilis were prepared by dissolving rotifer tissues and lorica with sodium dodecyl sulfate (SDS) and dithiothreitol (DTT) and were examined by scanning electron microscopy in order to obtain information on the functional morphology of these structures. The trophi are not composed of distinct parts but form a continuous structure of rigid pieces and connecting membranous regions. The membranous components allow movements of the rigid parts against each other and/or restrict the extent of such movements. The main hinge for the movement of the trophi is the membranous connection between the two rami; movements of rami and unci occur together since these parts are tightly connected by two narrow membranes in the subuncus region. The subunci seem to constitute masticating devices which act against grooved ridges of the rami and might make it feasible to disintegrate nutrient particles to as small as 1 m. Crushing of coarser nutrients might be performed by the opposite surfaces of the two rami.Abbreviations br bulla rami - c crest along the ventral surface of the manubrium - cd distal part of the manubrium (cauda) - cv proximal part of the manubrium (clava) - d1 entrance from the bowl-shaped recess at the dorsal side of the manubrium into one of the (three) cavities within the proximal part of the manubrium - d2 second dorsal entrance into one of the (three) cavities within the proximal part of the manubrium - eu edge at the distal end of the uncus which fits into a notch at the proximal end of the manubrium - gr small, oblong grooves at the distal surface of the reinforced projecting ridges of the rami - f fulcrum - h hinge between the two rami - l ligaments extending from the central membranes to the dorsal surfaces of the unci - m central membranous structures - ma manubrium - p partition between the cavities within the ramus - ps large, proximal surfaces of the rami - r ramus - rd reinforced ridge on the anterio/dorsal part of the ramus - rv ventral, triangular surface of the ramus - su subuncus - sur root-like structures connecting the subuncus with the uncus plate - t teeth-like proximal endings of the uncus ridges - u uncus - um membranous connection between uncus and manubrium - ur membranous connection between uncus and ramus in the subuncus region - uvr ridges on the ventral side of the uncus - ve ventral entrance into one of the (three) cavities within the proximal part of manubrium     

Scleritome construction,biofacies, biostratigraphy and systematics of the tommotiid Eccentrotheca helenia sp. nov. from the Early Cambrian of South Australia

Abstract: Large collections of Eccentrotheca helenia sp. nov. from the lower Cambrian Wilkawillina and Ajax limestones in the Arrowie Basin, South Australia, contain abundant low, cap‐shaped and high, laterally compressed isolated sclerites in addition to partially articulated tubular specimens. The scleritome of Eccentrotheca helenia sp. nov. is fully described for the first time and shown to be formed by ontogenetic fusion of sclerites into successively stacked sclerite rings, forming a larger, tubular structure. The apical termination of the tube is highly variable, but is primarily constructed by low, cap‐shaped sclerites and characterised by a central aperture of variable inclination. The adapical portion of the tube is predominantly constructed by high, laterally compressed sclerites, but individual sclerite rings can contain both cap‐shaped and laterally compressed sclerites along with sclerites of intermediate morphology. The apical aperture presumably housed organic structures for attachment to a hard substrate, but the scleritome also occasionally preserves small lateral perforations between fused sclerites, which may have served to stabilise the scleritome by providing additional points of anchorage. In the Arrowie Basin, E. helenia is found in association with archaeocyath‐microbial‐spongiomorph‐dominated bioherms and most likely inhabited pendant or cryptic habitats within these bioherms. Eccentrotheca‐like sclerites form an integral part of the scleritomes of many tommotiids which may confuse taxonomic analysis. Sclerites previously assigned to ‘E.’guano, consistently occur together with sclerites of Kulparina rostrata in stratigraphic intervals consistently older than strata hosting E. helenia. Rare fused specimens indicate that the sclerites of K. rostrata and ‘E.’guano belong to the same scleritome.     

The mouth apparatus of the Cambrian gilled lobopodian Pambdelurion whittingtoni

Omnidens is a large feeding apparatus composed of circlets of teeth, first documented from the early Cambrian of China. Originally interpreted as the oral cone of a radiodontan, it was later reinterpreted as the introvert of a priapulan. In both cases the Omnidens mouthparts underpinned estimates of gigantic (c. 2 m) body size. Recent evidence has been used to suggest that pharyngeal teeth and radially‐arranged oral plates in the stem‐group onychophoran Hallucigenia and the lower stem‐group euarthropod Jianshanopodia are homologous to structures of the introvert in priapulans and other scalidophorans, and are thus primitive characters for moulting animals (Ecdysozoa) as a whole. Here we show that the early Cambrian gilled lobopodian Pambdelurion whittingtoni from Sirius Passet, Greenland, possesses a mouth apparatus identical to Omnidens, being composed of the same three zones with detailed similarities of sclerites in each zone. An oral cone with rings of pharyngeal teeth, radial plates and outer scalid‐like plates are ecdysozoan characters retained in the euarthropod stem group. Omnidens from China probably belongs to an unrecognized Pambdelurion‐like animal rather than being part of a giant priapulan.     

Spermcasting of spermatozeugmata by the bivalves Nutricola confusa and N. tantilla

The dynamics and consequences of the varied reproductive modes of marine invertebrates is a rich and vibrant field of inquiry for ecological and evolutionary studies. One mode of reproduction that is not as well‐studied as others is “spermcasting” or “spermcast mating,” when males broadcast sperm and females retain eggs and brood developing embryonic stages. This type of reproduction occurs in two small (maximum adult shell length ~5–6 mm) venerid bivalves, Nutricola confusa and N. tantilla, that live in protected bays of the temperate eastern Pacific. Females of these species brood developing embryos in chambers formed by the inner demibranchs, and release fully formed juveniles. We discovered that upon exposing clams to fluvoxamine, a selective serotonin reuptake inhibitor, males release spermatozeugmata, clusters of sperm cells attached by their heads to a central core. Spermatozoa of Nutricola have unusually long, needle‐shaped heads that are approximately one quarter of the total length of the cell. These heads are curled and “packaged” into the hemispherical‐shaped cores of spermatozeugmata. The cores are about one‐third as long as the heads, and the tails protrude out of the opposite side of the cap of the core. The spermatozeugmata display two different swimming patterns, one where the tails beat in synchrony, and the other where they do not. The size of the cores is not significantly different in the two species, but spermatozeugmata of N. tantilla have significantly longer and wider tails than those of N. confusa. Advantages to spermcasting spermatozeugmata instead of individual spermatozoa may include enhanced dispersal and increased probabilities of fertilization. One consequence of spermatozeugmata (rather than individual spermatozoa) entering female brood chambers might be lowering of the effective population size. For species like these, which lack pelagic larvae, spermatozeugmata could increase dispersal and gene flow.     

Chancelloriid sclerites from the Lower Cambrian (Meishucunian) of eastern Yunnan,China, and the early history of the group

Chancelloriids are a group of enigmatic sessile animals that are covered with sclerites shaped as rosettes of spines, producing an appearance like that of a barrel cactus. They are known only from Cambrian rocks. Isolated sclerites of chancelloriids are widespread in small shelly faunas, but they have proven difficult to treat taxonomically due to the variation within and between individual animals. We report on large samples of chancelloriid sclerites from the Meishucunian (pre‐trilobitic Lower Cambrian) of eastern Yunnan Province, China, including material from the Dahai Member of the Zhujiaqing Formation (the Zhujiaqing section, Dahai, Huize County) and the Shiyantou Formation (the Xiaotan section, Yongshan County). The material from the Dahai Member appears to come from a single species, Chancelloriella irregularis. Statistical analysis of morphotype co‐occurrences in different samples suggests that several species are represented in the material from the Shiyantou Formation, which we herein tentatively place in four species, Allonnia erromenosa, Allonnia tetrathallis, Archiasterella charma sp. nov. and Archiasterella cf. pentactina. We suggest therefore that careful study of large collections of isolated chancelloriid sclerites permits the identification of different species, opening the possibility of their use in evolutionary or stratigraphical studies. In particular, in South China, it seems that Chancelloriella irregularis is characteristic of rocks of the Paragloborilus subglobosus – Purella squamulosa Assemblage Zone and the Watsonella crosbyi Assemblage Zone, whilst Archiasterella and Allonnia first appear in the overlying Sinosachites flabelliformis – Tannuolina zhangwentangi Assemblage Zone. C. irregularis is thus amongst the oldest well‐characterized chancelloriids, and the irregularity and poor organization of its sclerites relative to those of younger forms support the hypothesis that chancelloriid sclerites are compound structures arising from the fusion of originally separate elements, perhaps homologous with sclerites of halkieriids and other coeloscleritophorans. The similarity between the arrangement of rays in a chancelloriid sclerite and the arrangement of bubbles in small bubble clusters suggests that in many cases, aspects of the form of chancelloriid sclerites are the result of simple physical processes.     

Rice RAD51 paralogs play essential roles in somatic homologous recombination for DNA repair

Synthesis‐dependent strand annealing (SDSA) and single‐strand annealing (SSA) are the two main homologous recombination (HR) pathways in double‐strand break (DSB) repair. The involvement of rice RAD51 paralogs in HR is well known in meiosis, although the molecular mechanism in somatic HR remains obscure. Loss‐of‐function mutants of rad51 paralogs show increased sensitivity to the DSB‐inducer bleomycin, which results in greatly compromised somatic recombination efficiencies (xrcc3 in SDSA, rad51b and xrcc2 in SSA, rad51c and rad51d in both). Using immunostaining, we found that mutations in RAD51 paralogs (XRCC3, RAD51C, or RAD51D) lead to tremendous impairment in RAD51 focus formation at DSBs. Intriguingly, the RAD51C mutation has a strong effect on the protein loading of its partners (XRCC3 and RAD51B) at DSBs, which is similar to the phenomenon observed in the case of blocking PI3K‐like kinases in wild‐type plant. We conclude that the rice CDX3 complex acts in SDSA recombination while the BCDX2 complex acts in SSA recombination in somatic DSB repair. Importantly, RAD51C serves as a fulcrum for the local recruitment of its partners (XRCC3 for SDSA and RAD51B for SSA) and is positively modulated by PI3K‐like kinases to facilitate both the SDSA and SSA pathways in RAD51 paralog‐dependent somatic HR.     

The ultrastructure of the mastax of Filinia longiseta (Flosculariaceae, Rotifera): Informational value of the trophi structure and mastax musculature

The study contributes to the discussion of mastax evolution within Rotifera by giving an insight into the ultrastructure of the mastax in the rotifer species Filinia longiseta (Flosculariacea) and additionally into the bdelloid rotifer species Adineta vaga and Zelinkiella synaptae. The existence of cuticularized jaw elements (trophi) in the mastax, a muscular pharynx, is one of the defining rotiferan characters and the basis on which the monophyletic taxon Gnathifera Ahlrichs 1995a, comprising Rotifera, Gnathostomulida, Micrognathozoa and Acanthocephala, was erected. By means of SEM observations of the trophi and ultrathin serial sections (TEM) of the mastax, the internal and external organization of the jaw elements of F. longiseta is reconstructed. TEM sections of the incus of Filinia demonstrate that the fulcrum and the rami are built up by multitudes of tiny cuticular tubes. While tubular substructures in the rotiferan fulcrum have been described previously, distinct cuticular tubes as a substructure of the ramus have only been described for species belonging to the taxa Seisonidea and Bdelloidea so far ( [Koehler and Hayes, 1969] and [Ahlrichs, 1995b]). By comparing the appearance and arrangement of the cuticular tubes in the rami of F. longiseta to those found in species of Seisonidea and Bdelloidea, a higher degree of resemblance between the structures in F. longiseta and Bdelloidea can be reported. The occurrence of the ramus substructures in species of Seisonidea (Paraseison annulatus and Seison nebaliae) is given consideration to represent an intermediate between the ramus substructure of Bdelloidea/Flosculariacea and Ploima. Additionally, the mastax musculature of F. longiseta, being associated with the trophi, is described: A total of seven muscles are found that directly insert the jaw elements or are indirectly associated with them via muscle-to-muscle connections.     

Lasiolactols A and B Produced by the Grapevine Fungal Pathogen Lasiodiplodia mediterranea

A strain of Lasiodiplodia mediterranea, a fungus associated with grapevine decline in Sicily, produced several metabolites in liquid medium. Two new dimeric γ‐lactols, lasiolactols A and B ( 1 and 2 ), were characterized as (2S*,3S*,4R*,5R*,2′S*,3′S*,4′R*,5′R*)‐ and (2R*,3S*,4R*,5R*,2′R*,3′S*,4′R*,5′R*)‐(5‐(4‐hydroxymethyl‐3,5‐dimethyl‐tetrahydro‐furan‐2‐yloxy)‐2,4‐dimethyl‐tetrahydro‐furan‐3‐yl]‐methanols by IR, 1D‐ and 2D‐NMR, and HR‐ESI‐MS. Other four metabolites were identified as botryosphaeriodiplodin, (5R)‐5‐hydroxylasiodiplodin, (–)‐(1R,2R)‐jasmonic acid, and (–)‐(3S,4R,5R)‐4‐hydroxymethyl‐3,5‐dimethyldihydro‐2‐furanone ( 3  –  6 , resp.). The absolute configuration (R) at hydroxylated secondary C‐atom C(7) was also established for compound 3 . The compounds 1  –  3 , 5, and 6 , tested for their phytotoxic activities to grapevine cv. Inzolia leaves at different concentrations (0.125, 0.25, 0.5, and 1 mg/ml) were phytotoxic and compound 5 showed the highest toxicity. All metabolites did not show in vitro antifungal activity against four plant pathogens.     

A critical review of ontogenetic development in Terebellidae (Polychaeta)

Garraffoni, A.R.S. and Lana, P.C. 2009. A critical review of ontogenetic development in Terebellidae (Polychaeta). —Acta Zoologica (Stockholm) 91 : 390–401. This study reviews the ontogenetic variability of the head, the first segments and the uncini in Terebellidae, based on primary literature and development series of four terebellid species. We test hypotheses on character homologies and indicate informative characters for future phylogenetic analyses. The prostomium, identified as the region above the prototroch band of the larva, in addition to being the region of origin of the buccal tentacles, contains a series of nerves originating from the cerebrum. The peristomium, which contains the mouth, is innervated by the stomogastric nerve and consists of upper and lower lips and an internal pharynx. The loss of the first notochaetae and neurochaetae in the course of development is a recurrent pattern in terebellids. The claviform chaetae disappear with age and growth, and can be used to define the larval stage. Chaetogenesis shows that the long shaft‐shaped manubrium and posterior process develop from different regions. The uncini terminology ‘double rows’ was reinterpreted and renamed ‘inverted rows’, which better reflects the inversion of chaetal positions during ontogenetic development.     

Paterimitra pyramidalis from South Australia: scleritome,shell structure and evolution of a lower Cambrian stem group brachiopod

The tommotiid Paterimitra pyramidalis Laurie, 1986, is redescribed based on well‐preserved material from the lower Cambrian Wilkawillina, Wirrapowie and Ajax limestones of the Flinders Ranges, South Australia. The material shows that the scleritome of Paterimitra pyramidalis includes three sclerite morphotypes (S1, S2 and L). Detailed shell microstructure studies show striking similarities with both the paterinid brachiopod Askepasma toddense and the tommotiid Eccentrotheca helenia, which strengthens the suggested evolutionary link between tommotiids and brachiopods. Based on the partly articulated specimens and similarities in shell microstructure and sclerite morphology with Eccentrotheca, Paterimitra pyramidalis is reconstructed as a tube‐dwelling, epifaunal, sessile, filter‐feeder with an organic pedicle‐like attachment structure. The proposed reconstruction of the scleritome comprises a basal unit composed of one S1 and one S2 sclerite, as well as an unresolved number of L sclerites lining a coniform tubular structure.     

Teisseirei barattinia Roselli : the first sphinx moth trace fossil from palaeosols,and its distinct type of wall

The trace fossil Teisseirei barattinia, found in Cenozoic formations of Uruguay and Argentina, is an elongated chamber recognizable by its depressed cross‐section, antechamber, and its multi‐layered lining with an inner surface texture composed of densely packed sub‐rectangular to sub‐triangular pits. Our recent behavioural observations on larval and pupal stages of Sphingidae (Lepidoptera), particularly on Manduca rustica, suggest that Teisseirei barattinia is the pupation chamber of a sphinx moth. Last instar larvae of Manduca rustica, Eumorpha anchemolus and E. labruscae were placed in terraria to observe their burrowing behaviour and to recover pupation chambers. Chambers show depressed or plane convex cross‐sections as T. barattinia. The internal surface texture of walls is also similar to that of T. barattinia. The same pattern could be obtained experimentally by pressing the true legs of Manduca rustica larva against plasticine. The multi‐layered wall structure, shown by T. barattinia, is a new type of lining for insect trace fossils in palaeosols that result from soil packing combined with discharges of abundant liquid excretion by soft‐bodied larvae, as in the case of Manduca rustica. T. barattinia is the first trace fossil documented in palaeosols attributed to sphinx moths and supported by macro and micromorphological comparisons with extant pupation chambers. The shallow emplacement of moth pupation chambers in soils suggests that T. barattinia would be a good indicator of palaeosol upper horizons.     

Macroautophagy inhibition maintains fragmented mitochondria to foster T cell receptor‐dependent apoptosis

Mitochondrial dynamics and functionality are linked to the autophagic degradative pathway under several stress conditions. However, the interplay between mitochondria and autophagy upon cell death signalling remains unclear. The T‐cell receptor pathway signals the so‐called activation‐induced cell death (AICD) essential for immune tolerance regulation. Here, we show that this apoptotic pathway requires the inhibition of macroautophagy. Protein kinase‐A activation downstream of T‐cell receptor signalling inhibits macroautophagy upon AICD induction. This leads to the accumulation of damaged mitochondria, which are fragmented, display remodelled cristae and release cytochrome c, thereby driving apoptosis. Autophagy‐forced reactivation that clears the Parkin‐decorated mitochondria is as effective in inhibiting apoptosis as genetic interference with cristae remodelling and cytochrome c release. Thus, upon AICD induction regulation of macroautophagy, rather than selective mitophagy, ensures apoptotic progression.     

寒武纪叶足动物链状心网虫躯干骨板功能形态学研究*

链状心网虫(Cardiodictyon catenulum)是寒武纪澄江生物群中较为常见的叶足动物, 其躯干骨板的形态一直存在较大争议。本项研究显示该叶足动物的躯干具有一纵列马鞍状骨板, 每个体节具有单一的骨板, 每个骨板从背部延伸至躯干两侧。因此该叶足动物的骨板与其余具有成对或环状分布的躯干骨板的叶足动物存在显著的区别。骨板中央存在一个圆锥形凸起, 骨板边缘显著增厚且呈锯齿状。链状心网虫的躯干骨板边缘增厚和鞍点的凸起提升了整体的刚性; 锯齿状边缘也指示了更优的保护及防御功能。本项研究还发现链状心网虫骨板表面具有显微筛状结构, 筛孔被充填并保存为众多等距离分布的黄铁矿化瘤突, 与微网虫、怪诞虫及爪网虫躯干骨板的显微网状结构类似, 可能为纤细乳突的出口。本文认为: 寒武纪叶足动物的躯干骨板普遍具有显微筛状结构; 这些骨板除了保护与防御, 可能还有感觉的功能。每个躯干体节对应骨板为寒武纪叶足动物的独有衍征, 可能为背骨板的早期形态, 也可能由成对骨板愈合而来。     

On the origin of the putative furca of the Ostracoda (Crustacea)

The posterior end of body of the extant ostracods exhibits a pair of variously shaped appendages, commonly designated as furca(e), uropods or caudal rami, used for feeding and/or locomotion. It is here shown that the so-called furca of all extant ostracods has evolved from the (probably epipodal) vibratory plates of a pair of uropods. The transformation comprised the following steps: (a) complete reduction of the uropodal protopodite and endopodite; (b) sclerotisation of the lateral walls of the vibratory plates; (c) transformation of the branchial filaments into spines and/or claws; (d) re-orientation of the plates from posterodorsal to posteroventral. These modifications are suggested to have evolved in parallel with a change in function, from respiratory to locomotory and/or feeding. The most primitive condition, reminiscent of the ancestral state of character, is seen in the Platycopida: the ‘furca’ still appears similar in shape to the vibratory plates of the pair of sixth limbs. In the Podocopida the uropodal plates have been modified into plate-like, more often into rod-shaped rami mainly used for locomotion. In both the Platycopida and Podocopida the anus has remained in its original place, posterior to the ‘furcal’ plates or rami. In the Myodocopida and Halocyprida the uropodal vibratory plates are transformed into heavily developed lamellae bearing sturdy spines. They are activated by a complex apparatus of muscles and sclerites, the development of which necessitated the displacement of the anus from the end of the body towards its present place, anterior to the ‘furca’. The furca of the Ostracoda being not a ‘true’ furca, a change in terminology is proposed: uropodal plates or lamellae in the Platycopida, Palaeocopida and Myodocopida/Halocyprida; uropodal rami in the Podocopida. The so-called furcae of the Ostracoda being homologous structures, it is concluded that all extant ostracods belong to a monophyletic lineage.     

Cryptic Speciation in the Genus Cryptoglena (Euglenaceae) Revealed by Nuclear and Plastid SSU and LSU rRNA Gene

The photosynthetic euglenoid genus Cryptoglena is differentiated from other euglenoid genera by having a longitudinal sulcus, one chloroplast, two large trough‐shaped paramylon plates positioned between the chloroplast and pellicle, and lack of metaboly. The genus contains only two species. To understand genetic diversity and taxonomy of Cryptoglena species, we analyzed molecular and morphological data from 25 strains. A combined data set of nuclear SSU and LSU and plastid SSU and LSU rRNA genes was analyzed using Bayesian, maximum likelihood, maximum parsimony, and distance (neighbor joining) methods. Although morphological data of all strains showed no significant species‐specific pattern, molecular data segregated the taxa into five clades, two of which represented previously known species: C. skujae and C. pigra, and three of which were designated as the new species, C. soropigra, C. similis, and C. longisulca. Each species had unique molecular signatures that could be found in the plastid SSU rRNA Helix P23_1 and LSU rRNA H2 domain. The genetic similarity of intraspecies based on nr SSU rDNA ranged from 97.8% to 100% and interspecies ranged from 95.3% to 98.9%. Therefore, we propose three new species based on specific molecular signatures and gene divergence of the nr SSU rDNA sequences.     

Rhinomonas nottbecki n. sp. (Cryptomonadales) and Molecular Phylogeny of the Family Pyrenomonadaceae

The cryptomonad Rhinomonas nottbecki n. sp., isolated from the Baltic Sea, is described from live and fixed cells studied by light, scanning, and transmission electron microscopy together with sequences of the partial nucleus‐ and nucleomorph‐encoded 18S rRNA genes as well as the nucleus‐encoded ITS1, 5.8S, ITS2, and the 5′‐end of the 28S rRNA gene regions. The sequence analyses include comparison with 43 strains from the family Pyrenomonadaceae. Rhinomonas nottbecki cells are dorsoventrally flattened, obloid in shape; 10.0–17.2 μm long, 5.5–8.1 μm thick, and 4.4–8.8 μm wide. The inner periplast has roughly hexagonal plates. Rhinomonas nottbecki cells resemble those of Rhinomonas reticulata, but the nucleomorph 18S rRNA gene of R. nottbecki differs by 2% from that of R. reticulata, while the ITS region by 11%. The intraspecific variability in the ITS region of R. nottbecki is 5%. In addition, the predicted ITS2 secondary structures are different in R. nottbecki and R. reticulata. The family Pyrenomonadaceae includes three clades: Clade A, Clade B, and Clade C. All Rhinomonas sequences branched within the Clade C, while the genus Rhodomonas is paraphyletic. The analyses suggest that the genus Storeatula is an alternating morphotype of the genera Rhinomonas and Rhodomonas and that the family Pyrenomonadaceae includes some species that were described multiple times, as well as novel species.     

Morphology,ultrastructure, and molecular phylogeny of Wangodinium sinense gen. et sp. nov. (Gymnodiniales,Dinophyceae) and revisiting of Gymnodinium dorsalisulcum and Gymnodinium impudicum

The genus Gymnodinium includes many morphologically similar species, but molecular phylogenies show that it is polyphyletic. Eight strains of Gymnodinium impudicum, Gymnodinium dorsalisulcum and a novel Gymnodinium‐like species from Chinese and Malaysian waters and the Mediterranean Sea were established. All of these strains were examined with light microscopy, scanning electron microscopy and transmission electron microscopy. SSU, LSU and internal transcribed spacers rDNA sequences were obtained. A new genus, Wangodinium, was erected to incorporate strains with a loop‐shaped apical structure complex (ASC) comprising two rows of amphiesmal vesicles, here referred to as a new type of ASC. The chloroplasts of Wangodinium sinense are enveloped by two membranes. Pigment analysis shows that peridinin is the main accessory pigment in W. sinense. Wangodinium differs from other genera mainly in its unique ASC, and additionally differs from Gymnodinium in the absence of nuclear chambers, and from Lepidodinium in the absence of Chl b and nuclear chambers. New morphological information was provided for G. dorsalisulcum and G. impudicum, e.g., a short sulcal intrusion in G. dorsalisulcum; nuclear chambers in G. impudicum and G. dorsalisulcum; and a chloroplast enveloped by two membranes in G. impudicum. Molecular phylogeny was inferred using maximum likelihood and Bayesian inference with independent SSU and LSU rDNA sequences. Our results support the classification of Wangodinium within the Gymnodiniales sensu stricto clade and it is close to Lepidodinium. Our results also support the close relationship among G. dorsalisulcum, G. impudicum, and Barrufeta. Further research is needed to assign these Gymnodinium species to Barrufeta or to erect new genera.     

贵州织金寒武系戈仲伍组钉形类骨片化石研究*

钉形类(nail-shaped)骨片化石是华南寒武纪早期地层中常见的一类具矿化骨骼的小壳化石。本文系统研究了贵州织金戈仲伍剖面寒武系戈仲伍组的钉形类骨片化石, 发现织金地区钉形类化石主要以织金钉类和疑似的寒武钉类为主, 共4属9种。相较于前人研究, 本文新发现了织金钉类: Zhijinites tumourifomis、Z. lubricus、Z. clavus, 和疑似的寒武钉类: ?Deiradoclavus sp.、?Cambroclavus sp.。排除埋藏学假象后, 分析了钉形类不同化石属种保存方式及形态结构, 发现Zhijinites的多数种都存在盘体顶面凹陷结构, 并且Zhijinites部分种的锥体内壁有收缩现象或具有十字交错纤维结构, 这些发现能较好地揭示出Zhijinites各形态种间的相似性和差异性。分析钉形化石时空分布特点发现, 目前钉形类骨片化石最早在织金地区有化石记录, 之后在扬子地台内部辐射扩散, 并几乎同时辐射扩散至邻近陆块。此外, 本文讨论的疑似寒武钉类化石时代可下延至寒武纪幸运期, 可能是目前该类化石在全球的最早记录, 为探索寒武钉类化石的系统演化和地层学意义提供了新信息。