The cranial morphology and relationships of the aberrant Carboniferous amphibian Spathicephalus mirus Watson

The skull of Spathicephalus mirus Watson, an amphibian from the Namurian, basal Upper Carboniferous, of Scotland is described. It shares with the Loxommatoidea a closed palate, palatal ornament and antorbital vacuities, and the family Spathicephalidae is recognized as the sister group of the Loxommatidae. A new diagnosis of the Loxommatoidea is presented together with one of the Spathicephalidae. An analysis of the functional morphology of the Spathicephalus skull suggests that it was incapable of rapid jaw closure required for catching fish. Instead it is proposed that Spathicephalus was a sluggish bottom-dwelling filter-feeder of small, soft invertebrates.     

The water vascular system and functional morphology of Paleozoic asteroids

Asteroids of all geologic ages share a single basic body form, surficial skeletal arrangement, and aspects of water vascular construction. In almost all described Paleozoic species, however, either podial pores to the interior of the arm were lacking, or they are directed laterally, above the adambulacrals. They are internal and above the ambulacrals in known post-Paleozoic species and the Pennsylvanian Calliasterella. Certain features of the ambulacral skeletal arrangement also differ. Calliasterella is the closest known Paleozoic relative of post-Paleozoic asteroids. Classifications of asteroids that stress only overall form and surticial skeletal arrangement erroneously include Paleozoic and Holocene species in common ordinal or even lower level groupings. Taxonomic revision is premature: however, most known Paleozoic asteroids represent primitive lineages. Transitional forms allow reconstruction of events leading to the modern arrangement. Ampullar and skeletal arrangements of post-Paleozoic asteroids appear to offer some functional advantages over those of their precursors, but as early as the Ordovician, diverse feeding habits had evolved and ecological roles paralleled those of Holocene species.     

Mechanisms of light organ occlusion in flashlight fishes, family Anomalopidae (Teleostei:Beryciformes), and the evolution of the group

The circumtropical, nocturnal, shore-fish family Anomalopidae is characterized by a subocular luminous organ containing symbiotic luminous bacteria. The five known species are placed in four genera, one of which is new. Phthanophaneron is restricted to the eastern Pacific, Kryptophanaron to the western Atlantic, Photoblepharon is Indo-West Pacific in distribution and Anomalops is west Pacific. The symbiotic bacteria emit light continuously, and two superficially different mechanisms of occluding the glowing face of the organ are found. In Photoblepharon a black shutter of elastic skin is drawn up over the face of the organ, whereas in Anomalops the organ is rotated downward, so that only the heavily pigmented back of the organ is exposed. In Phthanophaneron and Kryptophanaron, both rotational and shutter mechanisms are present. Elucidation of the structures and linkages involved in light-organ occlusion reveals that the superficially different mechanisms are based on a common functional complex. In all four genera, the light organ is supported by a cartilaginous cup that articulates anteriorly with a cartilaginous stalk. Motive power for both the shutter and rotational mechanisms is supplied by the adductor mandibulae through a complex biomechanical linkage involving the ethmomaxillary ligament and a ligament unique to anomalopids, the Ligament of Diogenes. The structures involved in shutter erection and organ rotation are illustrated and described in detail for Photoblepharon and Anomalops and are compared with those in the other two forms; a functional hypothesis is advanced. Extrafamilial relationships of the Anomalopidae are discussed, and a hypothesis of the phylogenetic relationships of the four genera is derived from a cladistic analysis involving 19 non-light-organ characters and corroborated by some light-organ characters. Most characters associated with the light-organ complex cannot be polarized by conventional outgroup comparison, and the evolution of the light organ occlusion mechanisms is interpreted in light of the hypothesized phylogeny and a hypothesized ancestral mechanism. We propose that the common ancestor of anomalopids possessed a forced rotational mechanism like that of Phthanophaneron and Kryptophanaron. This was refined to a more efficient flipping rotational mechanism in Anomalops, the sister group of the lineage comprising the other three genera, within which the shutter mechanism was progressively refined. The ostensibly unnecessary complexity of the shutter mechanism is apparently a result of functional-morphological constraints imposed on the system by the pre-existence of a rotational mechanism. A brief zoogeographic scenario is proposed.     

Pseudotracheal tubes, larval head, and mycophagy in Sepedophilus (Coleoptera: Staphylinidae: Tachyporinae)

Newton (in: Wheeler, Q.; Blackwell, M. (eds), Fungus-Insect Relationships: Perspectives in Ecology and Evolution . New York: Columbia University Press, pp. 302–353, 1984) characterized five types of Sepedophilus larvae based on head structures and the external and internal features of the head of larvae of Sepedophilus type C are described in detail herein. A functional interpretation of structures involved with feeding is made on the basis of morphological and behavioural observations. Types C and D larvae possess tube-like epipharyngeal structures resembling dipteran labial pseudotrachea, which may play an important role in a specialized liquid-feeding process. Based on a preliminary analysis of head characters delimited by Newton (1984) it is shown that mycophagy has evolved once from a predatory ancestor, although some Sepedophilus groups may have mixed feeding strategies. The epipharyngeal tubes are demonstrated to be unique to mycophagous Sepedophilus in Coleoptera whereas the overall head structure is very similar to mycophagous larvae in the family Sphindidae.     

A comparative study of Lower Cambrian Halkieria and Middle Cambrian Wiwaxia

Two Cambrian lepidote metazoans known from different respective types of preservation have been compared in order to elucidate their biology and affinities. The widely distributed Lower Cambrian Halkieria is represented by isolated hollow sclerites, probably of originally calcareous composition. The Middle Cambrian Wiwaxia is known from the Burgess Shale as isolated sclerites (scales and spines) and as more or less complete individuals. Although Halkieria sclerites were mineralized and those of Wiwaxia were probably not, there are fundamental structural and morphological similarities between the two. Both bad an imbricating scaly and spiny armour consisting of hollow sclerites with a longitudinally fibrous structure. The sclerites did not grow, but were probably moulted during the course of ontogenetic growth. Halkieria and Wiwaxia are regarded as closely related. Both are referred to the Order Sachitida He 1980. The sclerite armour of Halkieria is reconstructed on the template provided by Wiwaxia. The interpretation of sachitid sclerites as protective armour is an alternative to the interpretation by Jell (1981, Alcheringa 5 )that sachitid sclerites were respiratory organs in an animal of probable annelid affinities. Sachitids are interpreted as sluggish, benthic deposit feeders that do not belong to any recognized phylum.     

On the origin systematic position of the calcareous-shelled inarticulate brachiopods

Available data on the anatomy, ontogeny embryology of Brachiopoda ( sensu lato ) suggest that this Phylum in the traditional view is in fact a clade of organization includes two stocks of lophophorate organisms of quite different origins. Their rank does not correspond to existing Class divisions. The phosphatic-shelled in articulates are regarded as a separate Class Lingulata. The Phylum Brachiopoda ( sensu stricto ) is restricted to the calcareous-shelled inarticulate articulate lineages. Ancestors of the calcareous-shelled brachiopods probably differentiated from the protolophophorates before the radiation of the other lophophorate stocks took place. The articulation of the valves appeared independently in several lineages during the early stages of brachiopod evolution.     

淡水龟科具闭壳结构龟类分类及系统进化研究进展

闭壳龟类是淡水龟科(Bataguridae)中一群具有"闭壳"结构的水栖或半水栖龟类的总称,即腹甲的腹盾和胸盾之间以可动的铰链韧带相连,使背甲和腹甲可以全部或部分闭合,它们是盒龟属(Cistoclemmys)、闭壳龟属(Cuo-ra)、锯缘龟属(Pyxidea)、齿缘龟属(Cyclemys)和果龟属(Notochelys),前4个属的龟类在中国均有分布。近几十年来,由于食用、传统中医药开发和宠物贸易的兴起,导致许多闭壳龟类野生物种数量急剧减少,并且当前许多亚洲闭壳龟的分类工作过多的依赖于市场购买的物种样本,这就使我们对闭壳龟属及种的归属划分变的较困难,因此对闭壳龟类物种种的界限的划分及属间系统发育关系的研究仍然是一个艰巨的挑战。通过对淡水龟科具有闭壳结构龟类的形态学研究,细胞遗传学研究以及分子系统学研究等进行了综述,以期为闭壳龟类的相关保护研究提供参考。     

Phylogeny of the flyingfish family Exocoetidae (Teleostei, Beloniformes)

The phylogeny of the flyingfish family Exocoetidae is studied cladistically, using 41 morphological characters encompassing early life history, and external and internal features. The monophyly of the family is supported by 10 synapomorphies. Within the family,Oxyporhamphus is the sister group to all other genera, the monophyly of the latter being defined by 10 synapomorphies.Fodiator is the sister group of genera characterized by the presence of chin barbels in juveniles.Parexocoetus is the sister group ofExocoetus, Cypselurus, Prognichthys andHirundichthys, the latter being defined by four synapomorphies. In the latter group,Exocoetus is the sister group of the other three genera. The phylogeny of the Exocoetidae is characterized by the stepwise upgrading of gliding capability, with sequential modifications of the caudal, pectoral and pelvic fins. The subfamily Oxyporhamphinae is resurrected.     

Setal morphology and cirral setation of thoracican barnacle cirri: adaptations and implications for thoracican evolution

Thoracic cirripedes are sessile crustaceans that use six pairs of thoracic appendages (the cirri) to catch and handle food. We used scanning electron microscopy to examine the cirri, which include one to three pairs of maxillipeds in six species of thoracican barnacles, in search of correlations between cirral setation and feeding mode. The species studied comprise both pedunculate and sessile forms and represent a wide range of marine habitats as well as morphologies, viz., Ibla cumingi , Octolasmis warwickii , Capitulum mitella , Pollicipes polymerus , Tetraclita japonica japonica and Megabalanus volcano . Of the pedunculates, I. cumingi has the least complex setation pattern consisting of only serrulate types. This is consistent with its very simplified feeding mode and an apparent inability to discriminate between food items. Octolasmis warwickii is slightly more modified, while both P. polymerus and C. mitella have a more diversified setation. The balanomorphan species exhibit by far the most complex cirral setation. This is consistent with the several types of suspension feeding seen in these species, their ability to identify and sort captured food items and even to perform microfiltration in the mantle cavity using the setae on their three pairs of maxillipeds. Our results indicate that in thoracican barnacles, adaptations in feeding behaviour are associated with changes in the setation pattern of the cirri. In addition, the setal types and their distribution on the cirri are potential new characters in future morphology-based analyses of the phylogeny of the Cirripedia Thoracica.     

南五味子属花的形态及其系统学意义

借助扫描电镜观察了南五味子属(Kadsura)中黑老虎(K.coccinea)、南五味子(K.japonica)和狭叶南五味子(K.angustifolia)雄花和雌花的形态发生过程, 三种植物花发育早期相似而发育后期出现分异。根据花形态发生早期的相似性, 支持南五味子属为单系起源;根据花形态发生后期的分异状态, 支持将南五味子属分为离蕊南五味子亚属(Subgenus Cosbaea)和南五味子亚属(Subgenus Kadsura)。借助扫描电镜观察了短梗南五味子(K.borneensis)和披针叶南五味子(K.lanceolata)花的形态, 将南五味子和狭叶南五味子的花与短梗南五味子和披针叶南五味子的花比较, 赞成在南五味子亚属下设南五味子组(Section Kadsura)和南洋南五味子组(Section Sarcocarpon)。根据在狭叶南五味子中观察到的两性花痕迹和在五味子属(Schisandra)东亚五味子(S.elongata)花中观察到的两性花, 本文认为现存五味子科(Schisandraceae )植物的单性花可能由具两性花结构的祖先演化而来。根据五味子科植物柱头与八角科(Illiciaceae)植物柱头的相似性, 不支持将五味子科从八角目(Illiciales)中分出而成立五味子目(Schisandrales)的观点。     

Initial morphological diversity as a criterion in deciphering turbellarian phylogeny

The most profound structural variety in morphofunctional systems and morphogenetic mechanisms, i.e. the highest morphological diversity, is observed in those groups where these systems and mechanisms are evolutionarily most primitive. Here, such variety can involve the basic body plan of a given phylum and the types of morphogenesis characteristic of it. This correlation provides a new criterion of evolutionary primitiveness, namely, the criterion of initial morphological diversity.The highest morphological diversity among turbellarian groups is observed in the order Acoela. Acoel turbellarians are archaic in most of their features, apparently being a group near the base of the turbellarian phylogenetic tree. Among other turbellarians there are a few groups that also are archaic in some few features (above all, the Catenulida), although on the whole they are more advanced than the Acoela. The Turbellaria as a whole is notable for its morphological diversity in comparison with other classes of the Scolecida.     

The postcranial skeleton of the Devonian tetrapod Tulerpeton curtum Lebedev

Postcranial remains of the Russian Late Devonian tetrapod Tulerpeton include the hexadactylous fore limb, hind limb, anocleithral pectoral girdle, squamation, and associated disarticulated postcranial bones. A cladistic analysis indicates that Tulerpeton is a reptiliomorph stem-group amniote and the earliest known crown-group tetrapod: Acanthostega and Ichthyostega are successively more derived plesion stem-group tetrapods and do not consititute a monophyletic ichthyostegalian radiation. Previous analyses suggesting a profound split in tetrapod phylogeny are thereby corroborated, and likewise the interpretation of Westlothiana as a stem-group amniote. The divergence of reptiliomorphs from batrachomorphs occurred before the Devonian-Carboniferous boundary. Tulerpeton originates from an entirely aquatic environment with a diverse fish fauna. The morphologies of its limbs and those of Devonian stem-tetrapods suggest that dactyly predates the elaboration of the carpus and tarsus, and that Polydactyly persisted after the evolutionary divergence of the principal lineages of living tetrapods. The apparent absence of a branchial lamina and gill skeleton suggests that Tulerpeton was primarily air-breathing, whereas contemporary stem-group tetrapods and more recent batrachomorphs retained greater emphasis on gill-breathing.