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1.
Trochoidea are a large superfamily of morphologically and ecologically diverse marine gastropods. We present here an appraisal of the composition and relationships among trochoidean families based on molecular data, with an especial focus on the family Trochidae. Bayesian analyses of sequences from three genes (18S rRNA, 28S rRNA and COI) including data from 162 vetigastropod species show that the gastropod family Trochidae (sensu  Hickman & McLean (1990 ), Natural History Museum Los Angeles County Science Series, 35, 1–169) is not monophyletic. Recognition of Chilodontidae, Solariellidae and Calliostomatidae at the family level is supported. Our new, more limited, definition of Trochidae includes the subfamilies Stomatellinae, Lirulariinae and Umboniinae and redefined Trochinae, Cantharidinae and Monodontinae. Halistylinae are provisionally retained in the Trochidae based on previous morphological studies. As redefined, Trochidae are a predominantly shallow‐water radiation in the tropics and subtropics. Some subfamilies and genera previously included in Trochidae have been moved to an enlarged family Turbinidae. The family Turbinidae has been redefined to include Turbininae, Skeneinae, Margaritinae, Tegulinae, Prisogasterinae and most surprisingly the commercially important genus Tectus Montfort, 1810. The new definition of Turbinidae means that the family includes both predominantly shallow and deep‐water clades as well as genera that are distributed across the globe from the poles to the tropics. A greater range of habitat is now seen in Turbinidae than in Trochidae. The redefined Trochidae and Turbinidae, together with Solariellidae, Calliostomatidae and Liotiidae, make up the superfamily Trochoidea. Phasianellidae and Colloniidae are recognized as belonging in a new superfamily, Phasianelloidea, and Angaria Röding, 1798 is recognized as belonging in a new superfamily, Angarioidea. Placement of Areneidae into a superfamily awaits further work.  相似文献   

2.
Williams, S.T. (2012). Advances in molecular systematics of the vetigastropod superfamily Trochoidea. —Zoologica Scripta, 41, 571–595. The gastropod superfamily Trochoidea Rafinesque, 1815 is comprised of a diverse range of species, including large and charismatic species of commercial value as well as many small or enigmatic taxa that are only recently being represented in molecular studies. This study includes the first sequences for rarely collected species from the genera Gaza Watson, 1879, Callogaza Dall, 1881, Antimargarita Powell, 1951 and Kaiparathina Laws, 1941. There is also greater taxon sampling of genera that have proved difficult to place in previous phylogenetic analyses, like Tectus Montfort, 1810, Tegula Lesson, 1832, Margarites Gray, 1847, Margarella Thiele, 1893 and trochoid skeneimorphs. There is also greater sampling of poorly represented families Solariellidae and Liotiidae. Bayesian analysis of combined gene data sets based on four (28S, 12S, 16S and COI) or five genes (plus 18S) suggests that there are eight, possibly nine families in Trochoidea including the families Margaritidae and Tegulidae, which are recognized for the first time at familial rank. Other trochoidean families confirmed are Calliostomatidae, Liotiidae, Skeneidae, Solariellidae, Trochidae and Turbinidae. A clade including Cittarium and the commercially important genera Rochia and Tectus may represent a possible ninth family, but this is not formally recognized or described here and awaits confirmation from further studies. Relationships among families were not generally well supported except in the 5‐gene tree. In the 5‐gene tree, Turbinidae, Liotiidae, Tegulidae, Cittarium, Rochia and Tectus form a well‐supported clade consistent with the previous molecular and morphological studies linking these groups. This clade forms another well‐supported clade with Margaritidae and Solariellidae. Trochidae is sister to Calliostomatidae with strong support. Subfamilial relationships within Trochidae are consistent with recent molecular studies, with the addition of one new subfamily, Kaiparathininae Marshall 1993 (previously a tribe). Only two subfamilies are recognized within Turbinidae, both with calcareous opercula: Prisogasterinae and Turbininae. Calliostomatidae includes a new subfamily Margarellinae. Its assignment to Calliostomatidae, although well supported by molecular evidence, is surprising considering morphological evidence.  相似文献   

3.
A new foraminiferal subfamily, Petschoricinae subfam. nov., with the type genus Petschorica Suchov, 2012, from the Ufimian (Upper Permian) of the Pechora Province is described. The subfamily belongs to the family Saccamminidae and differs from all other subfamilies of this family in the presence of small supplementary apertures, which are irregular in shape and scattering on the test surface. The family Saccamminidae is included in the order Saccamminida of the subclass Hormosinana Mikhalevich, 1992, class Nodosariata Mikhalevich, 1992.  相似文献   

4.
Abstract This paper reports a new subfamily, a new genus and a new species, that is, Pacrinae subfam. nov., Pacris gen. nov and Pacris xizangensis sp. nov in Gomphoceridae. The new subfamily is allied to Orinhippinae of Gomphoceridae and it differs from the latter by wings and tympanum absent. The new genus is similar to Orinhippus Uvarov, 1921 but differs from the latter in: (i) foveolae absent; (ii) tegmina absent; (iii) tympanum absent; (iv) hind margin of pronotum with incised in the middle. Type specimens are deposited in the Museum of Hebei University, Baoding, China.  相似文献   

5.
The taxonomic scheme of the two families of the order Isocrinida (Isocrinidae and Pentacrinidae) is given. The first family is divided at five subfamilies: Balanocrininae, Isocrininae, Metacrininae, Diplocrininae and Isselicrininae. Six genera are included in subfamily Balanocrininae: Balanocrinus (four species found in USSR), Laevigatocrinus (USSR: 3 species), Margocrinus (USSR: 4 species), Percevalicrinus (USSR: 5 species), Singularocrinus nov. gen. (monotypic) and Terocrinus nov. gen. (USSR: 1 species). Five fossil genera are included in subfamily Isocrininae: Chariocrinus (USSR: 1 species), Chladocrinus (USSR: 4 species), Isocrinus (USSR: 6 species), Raymondicrinus nov. gen. (Oligocene of USA : 2 species) and Tyrolecrinus nov. gen. (6 triassic species). Fossil representatives of three genera, namely, Metacrinus (Miocene-Recent), Nielsenicrinus (USSR: 4 species) and Cainocrinus (USSR: 1 species) are noted in subfamily Metacrininae. Five genera are included in subfamily Isselicrininae: Austinocrinus (USSR: 5 species), Buchicrinus (USSR: 5 species), Doreckicrinus (USSR: 1 species?), Isselicrinus (USSR: 4 species) and Praeisselicrinus (USSR: 1 species). Two genera are included in family Pentacrinidae: Pentacrinus (USSR: 1 species) and Seirocrinus (USSR: 4 species). Besides, the localities of 24 isocrinid species, systematic position of which is unknown, are listed (from Triassic upon Cretaceous). Three erroneous attributions to Isocrinida in USSR are pointed out. In the conclusion an outline of the phylogeny of the Isocrinida is discussed. For a majority of the wide-spread species in USSR figures are given.  相似文献   

6.
7.
Early Paleogene insectivore mammal associations of Asia include true insectivores (superorder Insectivora: order Lipotyphla: suborders Erinaceomorpha and Soricomorpha; orders Didymoconida and Leptictida) and insectivore-like placentals (superorder Ferae: order Cimolesta: suborders Didelphodonta, Palaeoryctida, and Pantolesta). The associations from Mongolia are the most taxonomically diverse. The Late Paleocene association from the Zhigden Member of the Naran-Bulak Formation of the Tsagan-Khushu and Naran-Bulak localities includes the following soricomorph insectivores: the micropternodontid Sarcodon pygmaeus Matthew et Granger and Hyracolestes ermineus Matthew et Granger (Sarcodontinae), the geolabidid Gobigeolabis verigranum Lopatin, the nyctitheriid Praolestes nanus Matthew, Granger et Simpson, P. maximus Kondrashov, Lopatin et Lucas (Praolestinae subfam. nov.), Jarveia erronea Kondrashov, Lopatin et Lucas (Asionyctiinae). Moreover, the Zhigden association includes the didymoconid Archaeoryctes euryalis Lopatin (Ardynictinae), the palaeoryctid Pinoryctes collector gen. et sp. nov., and the pantolestid Zhigdenia nemegetica gen. et sp. nov. (Pantolestinae). The Early Eocene association from the Bumban Member of the Naran-Bulak Formation of the Tsagan-Khushu locality includes the micropternodontid Prosarcodon maturus Lopatin et Kondrashov (Sarcodontinae); the nyctitheriids Bumbanius rarus Russell et Dashzeveg (Praolestinae), Oedolius perexiguus Russell et Dashzeveg, Edzenius lus gen. et sp. nov. (Asionyctiinae), and Eosoricodon terrigena Lopatin (Eosoricodontinae); the plesiosoricid Ordolestes ordinatus gen. et sp. nov. (Butseliinae); and the cimolestids Naranius infrequens Russell et Dashzeveg, Tsaganius ambiguus Russell et Dashzeveg, and Bagalestes trofimovi gen. et sp. nov. (Cimolestidae). The Middle Eocene association from the Khaychin Formation of the Khaychin-Ula 2 and Khaychin-Ula 3 localities includes the erinaceomorphs Eogalericius butleri Lopatin and Microgalericulus esuriens gen. et sp. nov. (Erinaceidae, Galericinae), the soricomorphs Metasarcodon reshetovi Lopatin et Kondrashov (Micropternodontidae, Sarcodontinae), Soricolestes soricavus Lopatin (Soricidae, Soricolestinae), and Asiapternodus mackennai Lopatin (Apternodontidae, Asiapternodontinae subfam. nov.); the didymoconids Ardynictis captor Lopatin (Ardynictinae), Khaichinula lupula gen. et sp. nov. (Didymoconinae), Kennatherium shirense Mellett et Szalay, and Erlikotherium edentatum gen. et sp. nov. (Kennatheriinae subfam. nov.); and the palaeoryctid Nuryctes gobiensis Lopatin et Averianov (Palaeoryctidae). Late Paleocene insectivores from the Dzhilga 1a locality (Kazakhstan) comprise the nyctitheriids Voltaia minuta Nessov and Jarveia minuscula Nessov (Asionyctiinae). The faunal assemblage dated terminal Early Eocene from the Andarak 2 locality (Kyrgyzstan) includes the micropternodontid Metasarcodon udovichenkoi (Averianov), the erinaceid Protogalericius averianovi gen. et sp. nov. (Galericinae), and the palaeoryctids Nuryctes alayensis Lopatin et Averianov and Palaeoryctidae gen. et sp. indet. From the end of the Paleocene to the onset of the Middle Eocene, the taxonomic composition and ecological structure of insectivore communities of Central Asia gradually changed, insectivore-like placentals and primitive soricomorph groups were replaced by the Recent families of Lipotyphla. The morphological and evolutionary study of Early Paleogene Asian insectivores has provided important data on phylogenetic relationships of the Insectivora. The family Micropternodontidae is divided into the subfamilies Sarcodontinae and Micropternodontinae. The earliest insectivore family Geolabididae is recorded in the Paleogene of Asia. A new classification of the family Nyctitheriidae, dividing it into the subfamilies Nyctitheriinae, Amphidozotheriinae, Asionyctiinae, Eosoricodontinae, and Praolestinae subfam. nov., is proposed. Based on the morphological continuity between Eosoricodontinae (Nyctitheriidae) and Soricolestinae (Soricidae), the family Soricidae is proposed to originate from eosoricodontine nyctitheriids. The family Plesiosoricidae is divided into the subfamilies Butseliinae and Plesiosoricinae. A new subfamily, Asiapternodontinae subfam. nov., is established in the family Apternodontidae. The analysis of evolutionary transformations of the dental system suggests the continuity of molar types in the suborder Soricomorpha, which supports the validity of the infraorders Tenrecomorpha and Soricota (the latter includes the superfamilies Micropternodontoidea, Nesophontoidea, Soricoidea, Talpoidea, and Solenodontoidea). The subfamily Galericinae (Erinaceidae) is recorded in Asia at the Early-Middle Eocene boundary. The family Didymoconidae is divided into the subfamilies Ardynictinae, Didymoconinae, and Kennatheriinae subfam. nov. Some members of the subfamily Kennatheriinae display a clear edentate functional pattern, which is atypical for insectivores and is interpreted as an adaptation for feeding on colonial insects. The following scenario of insectivore evolution, describing the major stages of their history, is proposed: (1) in the first half of the Late Cretaceous, the first occurrence of Insectivora (probably in North America); (2) in the second half of the Late Cretaceous, the primary radiation of Insectivora, establishment of Leptictida, Didymoconida, and Lipotyphla; detachment of Erinaceomorpha and Soricomorpha; (3) at the Cretaceous-Paleocene boundary, the primary radiation of Soricomorpha and establishment of Tenrecomorpha (Africa) and Soricota (North America); (4) in the Paleocene, expansion of Soricota in the Northern Hemisphere, the primary radiation of Erinaceomorpha, and emergence of Erinaceidae (North America); (5) at the Paleocene-Eocene boundary, radiation of Soricota and Erinaceidae; (6) at the Early-Middle Eocene boundary, appearance of Soricidae, Talpidae, and Galericinae; (7) in the Middle Eocene-Oligocene, replacement of primitive groups by Recent families and related groups and the formation of the Recent subfamilial diversity of the families Soricidae, Talpidae, Erinaceidae, and Tenrecidae; (8) in the Miocene-Pliocene, disappearance of primitive groups of the Recent families, a decrease in the diversity of Erinaceomorpha, extensive radiation of Soricidae and the formation of the Recent generic diversity of insectivores.  相似文献   

8.
New taxa of Orthoptera Ensifera are described in the families Mogoplistidae [Protomogoplistes asquamosus gen. et sp. nov. (Upper Cretaceous) in the subfamily Protomogoplistinae subfam. nov. and Archornebius balticus gen. et sp. nov. (Eocene), Pseudarachnocephalus gen. nov., P. dominicanus sp. nov., and P. latiusculus sp. nov. (all Miocene) in Mogoplistinae] and Gryllidae [Eopentacentrus borealis gen. et sp. nov. (Eocene), ?Grossoxipha feminea sp. nov. (Miocene), and Apentacentrus copalicus sp. nov. in the subfamily Pentacentrinae, ?Cyrtoxipha electrina sp. nov. and ?Cyrtoxipha illegibilis sp. nov. (both Miocene) in Trigonidiinae, and Baltonemobius fossilis gen. et sp. nov. (Eocene) in Nemobiinae]. The Miocene genera Proanaxipha Vickery et Poinar and Grossoxipha Vickery et Poinar are transferred from the subfamily Trigonidiinae to Pentacentrinae. P. latoca Vickery et Poinar and Abanaxipha longispina Vickery et Poinar are redescribed; the male of the latter species is described for the first time.  相似文献   

9.
Two new genera (monotypic Samarabatrachus gen. nov. (S. bjerringi sp. nov.) and Syrtosuchus gen. nov. (including S. samarensis (Sennikov, 1981) and S. morkovini sp. nov) and a new species of the genus Selenocara Bjerring (S. rossica sp. nov.) are described based on revision of the original material of the form previously known as Wetlugasaurus samarensis. The genera Selenocara and Samarabatrachus gen. nov. positioned at the base of radiation of Triassic capitosaurids are combined into a new subfamily, Selenocarinae subfam. nov. The genus Syrtosuchus gen. nov., which is undoubtedly a derivative of early capitosaurids (Selenocara or a closely related genus), shows some typical benthosuchid features and is assigned to a separate benthosuchid subfamily, Syrtosuchinae subfam. nov. The diagnoses of the genera Wetlugasaurus Riabinin and Selenocara are amended. For the territory of the Obschii Syrt Highland, the genera Selenocara, Samarabatrachus gen. nov., and Syrtosuchus gen. nov. are regarded as key members of a separate Early Triassic tetrapod assemblage (Selenocara–Syrtosuchus Fauna), which is intermediate between the Tupilakosaurus and Benthosuchus faunas and dated Late Induan (Dienerian).  相似文献   

10.
In order to place a newly discovered species Antigracilus costatus gen. sp. n. from the Lower Cretaceous Yixian Formation (China) and to assess previously unplaced fossil taxa, we investigated the relationships of extant and extinct lineages of Histeridae based on three data sets: (i) 69 morphological characters belonging to 48 taxa (representing all 11 subfamilies and 15 of 17 tribes of modern Histeridae); (ii) partitioned alignment of 6030 bp from downloaded nucleotide sequences (28S, CAD, COI, 18S) of 50 taxa (representing 10 subfamilies and 15 of 17 tribes of modern Histeridae); and (iii) a combined morphological and molecular dataset for 75 taxa. Phylogenetic analyses of the morphology and combined matrices recovered the new Lower Cretaceous taxon as a sister group to remaining Histeridae and it is placed in †Antigracilinae subfam. n. †Antigracilinae constitutes the earliest record of Histeridae from the Lower Cretaceous Yixian Formation (∼125 Myr), backdating the minimum age of the family by 25 Myr from the earliest Cenomanian (~99 Myr) to the Barremian of the Cretaceous Period. Our molecular phylogeny supports Histeridae to be divided into seven different clades, with currently recognised subfamilies Abraeinae (sensu lato), Saprininae, Chlamydopsinae, and Histerinae (sensu lato) recovered as monophyletic, while Dendrophilinae, Onthophilinae, and Tribalinae are polyphyletic taxa. The Burmese amber species †Pantostictus burmanicus Poinar & Brown is placed as a sister group to the tribe Plegaderini (Abraeinae) and was assigned as a new tribe Pantostictini trib. n. Both molecular and combined phylogenies recovered the subfamilies Trypanaeinae and Trypeticinae deeply within the subfamily Abraeinae (sensu lato), and they are downgraded into Trypanaeini stat. n. and Trypeticini stat. n.  相似文献   

11.
We describe the oldest Kalligrammatidae, two distantly related species of different subfamilies from the Lower Jurassic (lower Toarcian) of Germany: Liassopsychops curvatus Bode, 1953, sit. nov. (Liassopsychopinae n. subfam.) and Ophtalmogramma klopschari n. gen. n. sp. (Kallihemerobiinae). They lived in warm and relatively dry conditions. Subfamily Liassopsychopinae includes the Jurassic genera Liassopsychops and Huiyingogramma, sit. nov., which bear forewings characterized by Sc and RA not fused distally; MP, CuA, CuP, and A1 dichotomously branched; and a well-developed central eye-spot. The forewing of Ophtalmogramma n. gen. is most similar to that of Apochrysogramma Yang et al., 2011. The diversity of early Toarcian kalligrammatids indicates a late Triassic–earliest Jurassic origin of the family. A modified classification of the central eye-spots is proposed based on the presence/absence of four main components, i.e., the central pigmented disc (A), swellings (B), ocules (C), and outer rings (D). The function of the swellings is unclear, but they may have served as pheromone containers.  相似文献   

12.
The bivalve family Ostreidae has a worldwide distribution and includes species of high economic importance. Phylogenetics and systematic of oysters based on morphology have proved difficult because of their high phenotypic plasticity. In this study we explore the phylogenetic information of the DNA sequence and secondary structure of the nuclear, fast-evolving, ITS2 rRNA and the mitochondrial 16S rRNA genes from the Ostreidae and we implemented a multi-locus framework based on four loci for oyster phylogenetics and systematics. Sequence-structure rRNA models aid sequence alignment and improved accuracy and nodal support of phylogenetic trees. In agreement with previous molecular studies, our phylogenetic results indicate that none of the currently recognized subfamilies, Crassostreinae, Ostreinae, and Lophinae, is monophyletic. Single gene trees based on Maximum likelihood (ML) and Bayesian (BA) methods and on sequence-structure ML were congruent with multilocus trees based on a concatenated (ML and BA) and coalescent based (BA) approaches and consistently supported three main clades: (i) Crassostrea, (ii) Saccostrea, and (iii) an Ostreinae-Lophinae lineage. Therefore, the subfamily Crassotreinae (including Crassostrea), Saccostreinae subfam. nov. (including Saccostrea and tentatively Striostrea) and Ostreinae (including Ostreinae and Lophinae taxa) are recognized. Based on phylogenetic and biogeographical evidence the Asian species of Crassostrea from the Pacific Ocean are assigned to Magallana gen. nov., whereas an integrative taxonomic revision is required for the genera Ostrea and Dendostrea. This study pointed out the suitability of the ITS2 marker for DNA barcoding of oyster and the relevance of using sequence-structure rRNA models and features of the ITS2 folding in molecular phylogenetics and taxonomy. The multilocus approach allowed inferring a robust phylogeny of Ostreidae providing a broad molecular perspective on their systematics.  相似文献   

13.
In the framework of a large-scale rock sampling in Continental Antarctica, a number of yeasts have been isolated. Two strains that are unable to grow above 20 °C and that have low ITS sequence similarities with available data in the public domain were found. The D1/D2 LSU molecular phylogeny placed them in an isolated position in the genus Taphrina, supporting their affiliation to a not yet described species. Because the new species is able to grow in its anamorphic state only, the species Taphrina antarctica f.a. (forma asexualis) sp. nov. has been proposed to accommodate both strains (type strain DBVPG 5268T, DSM 27485T and CBS 13532T). Lalaria and Taphrina species are dimorphic ascomycetes, where the anamorphic yeast represents the saprotrophic state and the teleomorph is the parasitic counterpart on plants. This is the first record for this genus in Antarctica; since plants are absent on the continent, we hypothesize that the fungus may have focused on the saprotrophic part of its life cycle to overcome the absence of its natural host and adapt environmental constrains. Following the new International Code of Nomenclature for Algae, Fungi and Plants (Melbourne Code 2011) the reorganization of TaphrinaLalaria species in the teleomorphic genus Taphrina is proposed. We emend the diagnosis of the genus Taphrina to accommodate asexual saprobic states of these fungi. Taphrina antarctica was registered in MycoBank under MB 808028.  相似文献   

14.
The phylogeny and taxonomy of the brachiopod family Linoproductidae are revised. The change in the distributional pattern of spines and distinctive structure of the median lobe of the cardinal process are shown to be the main apomorphies in the family evolution. A new subfamily, Linispininae, and the included new genera, Linispinella and Linispinus, are described. In the nominotypical subfamily Linoproductinae, a new genus Linoproductoides and two new species included in this genus are described from the Vereiskian deposits of the Moscow Region. The new species Linispinus riparius (Trautschold), L. longus sp. nov., and L. staricensis (Ivanov) are described from the Kashirskian deposits. Another new species is tentatively described as “Linoproductus” kabanovi.  相似文献   

15.
To elucidate the evolutionary relationships of the major lineages within the moth family Nolidae, we analysed a molecular dataset comprising eight independent gene regions (6.4 kbp), cytochrome c oxidase subunit I (COI) from the mitochondrial genome, and elongation factor‐1α (EF‐1α), ribosomal protein S5 (RpS5), carbamoylphosphate synthase domain protein (CAD), cytosolic malate dehydrogenase (MDH), glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), isocitrate dehydrogenase (IDH) and wingless genes from the nuclear genome, using parsimony and model‐based evolutionary methods (maximum likelihood and Bayesian inference). Our analyses revealed a well‐resolved phylogenetic hypothesis, again recovering the six previously recognized families within Noctuoidea (i.e. Oenosandridae, Notodontidae, Euteliidae, Erebidae, Nolidae and Noctuidae), and monophyly of the quadrifid Noctuoidea (i.e. Euteliidae, Erebidae, Nolidae and Noctuidae). The family Nolidae is diagnosed and characterized by two synapomorphies from morphology: construction of a ridged boat‐shaped cocoon that bears a vertical exit slit at one end; and two other morphological character states: elongation of the forewing retinaculum into a bar‐like or digitate condition and possession of a postpiracular counter‐tympanal hood. We present a new phylogenetic hypothesis for Nolidae consisting of eight strongly supported subfamilies, two of which are erected here: Diphtherinae, Risobinae, Collomeninae subfam. nov., Beaninae subfam. nov., Eligminae, Westermanniinae, Nolinae and Chloephorinae. Where we are able, each monophyletic lineage is diagnosed by morphological autapomorphies and within each subfamily, monophyletic tribes and subtribes are circumscribed, most of which are also diagnosable by morphological apomorphies. We also describe two new taxa: Gelastocerini trib. nov. and Etannina subtrib. nov. The Neotropical subfamily Diphtherinae, here newly circumscribed, is considered to be the plesiomorphic sister lineage to the rest of Nolidae. Diphtherinae are characterized by loss of the proximal pair of metatibial spurs in males and by the presence of a frontal tubercle, which is presumably associated with a derived strategy of emergence from the cocoon.  相似文献   

16.
Testicular spermatozoa and sperm development in the archaeogastropod Calliotropis glyptus Watson (Trochoidae: Trochidae) are examined using transmission electron microscopy and formalin-fixed tissues. During spermiogenesis, the acrosome, formed evidently through fusion of Golgi-derived proacrosomal vesicles, becomes deeply embedded in the condensing spermatid nucleus. Two centrioles (proximal and distal), both showing triplet microtubular substructure, are present in spermatids—the distal centriole giving rise to the sperm tail and its associated rootlet. During formation of the basal invagination in the spermatid nucleus, centrioles, and rootlet move towards the nucleus and come to lie totally within the basal invagination. Mitochondria are initially positioned near the base of the nucleus but subsequently become laterally displaced. Morphology of the mature spermatozoon is modified from that of the classic primitive or ect-aquasperm type by having 1) the acrosome embedded in the nucleus (the only known example within the Mollusca), 2) a deep basai invagination in the nucleus containing proximal and distal centrioles and an enveloping matrix (derived from the rootlet), 3) laterally displaced periaxonemal mitochondria, and 4) a tail extending from the basal invagination of the nucleus. Implantation of the acrosomal complex and centrioles within imaginations of the nucleus and lateral displacement of mitochondria effectively minimize the length of the sperm head and midpiece. Such modifications may be associated with motility demands, but this remains to be established. The unusual features of C. glyptus spermatozoa, though easily derivable from ‘typical’ trochoid sperm architecture, may prove useful in delineating the genus Calliotropis or tracing its relationship to other genera within the trochid subfamily Margaritinae.  相似文献   

17.
The family Asclepiadaceae (Dicotyledones) was created by Brown in 1810 by splitting in two the family Apocynaceae of Jussieu established in 1789. The morphological characters used to make this distinction were mainly palynological, such as presence of tetrads or pollinia and number and orientation of pollinia. Those characters, still used in higher taxonomic delimitation (families, subfamilies, and tribes), are here critically reexamined and compared to a molecular phylogeny obtained with one of the more variable plastid genes (matK) of 46 species in the order Gentianales. In this molecular phylogeny, Asclepiadaceae form a monophyletic group derived from within Apocynaceae. Each of the subfamilies of Asclepiadaceae is monophyletic and based on reliable palynological characters, but palynological characters are not useful to delimit tribes of the subfamily Asclepiadoideae. Based on the molecular data, these tribes have undergone parallelisms in several reproductive traits.  相似文献   

18.
19.
20.
The analysis of the morphological features of the genera of the family Linoproductidae in the Late Paleozoic substantiates its three subfamilies as three evolutionary trends beginning with the initial subfamily Coopericinae Lazarev, 2004, which is known from the beginning of the Early Carboniferous and two its derivatives: subfamily Linipalinae subfam. nov., which appeared in the Podolskian Time (Upper Moscovian Age), and subfamily Linoproductinae Stehli, 1954, which appeared in the Kasimovian Age. The problems and prospects of the further detailing of the system of these subfamilies are discussed. Three new species of the genus Sublinoproductus are described from the Lower Permian of Northern Timan.  相似文献   

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