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1.
Envall  Mats  Norenburg  Jon L. 《Hydrobiologia》2001,456(1-3):145-163
Interstitial nemerteans of the genus Ototyphlonemertes are difficult to organize into traditional morphospecies. They occur in a multitude of slightly different local varieties that form a seemingly continuous morphological cline. In this paper, we summarize most published morphological data on the group, plus 73 new records of geographic varieties from the Mediterranean Sea in the East to the Sea of Japan in the West. We summarize morphological variation, partition traits into character and character states, propose a standardized protocol for examination of live specimens and discuss the phylogenetic structure of the group. The phylogenetic discussion leads to a hypothesis that partitions all varieties (including the established species) into six groups. These are the smallest morphologically homogenous sets of varieties (corresponding to traditional morphospecies) we can diagnose on phylogenetically reliable traits. Variation within the groups appears to be unreliable phylogenetic markers that may distinguish ecological forms rather than relatedness. However, we distinguish four of the groups by combinations of two traits, one apomorphy for a more inclusive group and one plesiomorphy, and the remaining two by one trait each that may be either a unique plesiomorphy or an apomorphy depending on the rooting, and most of them may thus join paraphyletic groups of cryptic monophyletic units. We call this kind of group phylomorph and name them the Duplex-, Pallida-, Cirrula-, Fila-, Lactea- and Macintoshi-morph (referring to the first established species within each group, i.e. Ototyphlonemertes duplex, O. pallida, O. cirrula, O. fila, O. lactea and O. macintoshi respectively). The phylogenetic scheme provides a simple tool to allocate geographical varieties to a group of possible `species' and a phylogenetic null-hypothesis for further tests with genetic data.  相似文献   

2.
Two species of the interstitial nemerteans from the intertidal zone of Van Phong Bay (southern Vietnam) are described. By the structure of the proboscis and statocysts, the nemertean Ototyphlonemertes ani sp. n. can be referred to the species group “Lactea” (sensu Envall, Norenburg, 2001), but it differs from other species of this group by the presence of cerebral organs and caudal cirri. The second species new for the region is very similar to O. martynovi, but differs from it in having 2 to 3 cephalic cirri in group C (instead of 4 to 6 cirri found in O. martynovi).  相似文献   

3.
Mats  Envall 《Journal of Zoology》1996,238(2):253-277
The species Ototyphlonemertes correae sp. nov. and O. duplex Bürger, 1895 (Ototyphlonemertidae) are described. The new species possesses a smooth stylet, oligogranular statolith and nephridia. Phylogenetic relationships are reconstructed for 21 Ototyphlonemertes species, based on an analysis of 18 morphological characters, totalling 43 character states. The most informative characters are stylet structure, basis shape, statolith shape and nephridia. Based on the phylogeny, the subgenus Otohelicophora (Greek, helicophora meaning the spiral carriers) is separated, which is defined with reference to the synapomorphy 'spiral stylet'.  相似文献   

4.
Zusammenfassung Ototyphlonemertes pallida (Keferstein, 1862) hat zwei Statocysten, die unmittelbar hinter den Dorsalganglien auf den verlängerten Ventralganglien liegen. Jede Statocyste besteht aus einer Statolithenkammerzelle, mehreren Nervenzellen und einer Anzahl Hüllzellen und ist von einer dicken Basalmembran umgeben. Die Statolithenkammerzelle umschließt in der Regel drei Statolithenkammern, die von einer doppelten Membran umgeben sind und untereinander in Verbindung stehen. Sie enthalten je einen frei beweglichen Statolithen. Cilien und Ciliarstrukturen fehlen. Auf der Dorsalseite der Statocyste liegen mehrere stark verästelte Nervenzellen, die einen gemeinsamen Strang bilden. In der Nähe der Statolithenkammerzelle spalten sie sich auf und bilden pro Kammer eine oder mehrere synaptische Platten mit elektrischen Synapsen. Die Statolithenkammerzelle wird von zahlreichen Hüllzellen umgeben, die durch Desmosomen fest verbunden und zusätzlich in der ventralen Hälfte der Statocyste an den Außenseiten stark miteinander verzahnt sind. Die Hüllzellen unterscheiden sich im Aufbau deutlich von den beiden anderen Zelltypen und sind nicht an der Reizperzeption oder Reizleitung beteiligt. Zu den cilienlosen Statocysten bei Coelenteraten, Turbellarien, Holothurien, Xenoturbella und Tunicaten-Larven bestehen keine engeren morphologischen Beziehungen. Die Statocyste von O. pallida stellt eine Bildung sui generis innerhalb der Nemertinen dar.
Ultrastructure of the Statocyst of Ototyphlonemertes pallida (Keferstein, 1862) (Nemertini)
Summary Ototyphlonemertes pallida (Keferstein, 1862) has two statocysts, which are situated just behind the dorsal ganglions on the elongations of the ventral ganglions. Each statocyst consists of one statolith chamber cell, some nerve cells and a number of covering cells and is surrounded by a thick basement membrane. Usually the statolith chamber cell encloses three statolith chambers, which are intercommunicated and surrounded by a double membrane. Each chamber contains a single mobile statolith. Cilia and ciliary structures are lacking. Within the dorsal part of the statocyst some very ramified nerve cells are situated, which form a nerve fibre. In the vicinity of the statolith chamber cell the nerve cells split up into synaptical plates with electric synapses; there are one or several synaptical plates at the level of each chamber. The statolith chamber cell is surrounded by numerous covering cells, which are connected by desmosomes and additionally linked together at the outside in the ventral part of the statocyst. With regard to their structure the covering cells differ greatly from the other cell types, and they do not participate in impulse perception and impulse conduction. There do not exist any closer morphological relations to the statocysts lacking cilia in Coelenterates, Turbellaria, Holothuria, Xenoturbella and Tunicata. The statocyst of O. pallida represents an indigenous structure within the Nemerteans.

Abkürzungen bm Basalmembran - d Dendrit - de Desmosom - dg Dorsalganglion - dm doppelte Membran der Statolithenkammer - ds deltaförmige Strukturen - ep Epidermis - es elektrische Synapse - hms Hautmuskelschlauch - hz Hüllzelle - k Zellkern - m Mitochondrium - ma abgewandeltes Mitochondrium - mu Muskulatur - n Nervenstrang - nv Neurosekretvesikel - nz Nervenzelle - rs Rüsselscheide - sc Statocyste - sk Statolithenkammer - skz Statolithenkammerzelle - sp synaptische Platte - st Statolith - v Vakuole - vg Ventralganglion  相似文献   

5.
The fixation of trans-(NH3)2Cl2 Pt(II) to poly(I)·poly(C) at low rb (< 0.05) leads to the formation of two complexed species. The major species (ca. 82% of bound platinum) involves coordination of platinum to a single hypoxanthine base, while the other species involves coordination of two hypoxanthine bases, which are either far apart on the same strand or on separate poly(I) strands, to the platinum. These same two species are found after reaction with poly(I), as are two other species throughout the entire rb range studied (rb = 0–0.30). The latter two species are assigned to trans-Pt bound to two bases on a poly(I) strand with (a) one or (b) two free bases between the two bound bases. These two species, (a) and (b), account for ca. 35% of the bound platinum, although the 1:1 species remains dominant (ca. 55%). These two additional species are observed at high rb (>0.075) after reaction with poly(I)·poly(C) but as very minor species. They are formed by reaction with melted poly(I) loops. Also at high rb, we have observed a shifted cytidine H5 resonance arising from interaction of trans-Pt with a melted loop of poly(C). Most probably, this arises from an intramolecular poly(I) to poly(C) crosslink. Results from the reaction of trans-Pt with poly(C) are presented for comparison.  相似文献   

6.
An endangered tetraploid spined loach species, Cobitis takenoi (Cypriniformes: Cobitidae; hereafter called Tango loach) is known to inhabit only a single river in Kyoto Prefecture, Japan. Since Tango loach was discovered recently, in 2010, and only described in 2016, its morphology, ecology, and genetics are not well studied. Another tetraploid spined loach species Cobitis sp. BIWAE type A (hereafter, called Ohshima loach) inhabits the same river. The two loaches are reported as morphologically distinguishable from each other. Although the habitats of the two species in the river are segregated (Ohshima loach and Tango loach inhabit the upper and lower reaches, respectively), they overlap to a small degree in the boundary area. Recently, some individuals with morphological characteristics that are intermediate between the two species were found in the overlap zone. It was suspected that hybrids between the two species were produced since breeding seasons of the two species overlapped. To investigate whether the two species produce hybrids, we performed mitochondrial and nuclear DNA analyses on the unidentifiable individuals. Eight individuals unidentifiable to the species level collected in the river between 2017 and 2018 were examined and compared with the Tango and Ohshima loach species. Using mitochondrial DNA (mtDNA) cytochrome b analysis, we found that six individuals had mtDNA types identical to Tango loach and two individuals had mtDNA types identical to Ohshima loach. Furthermore, sequencing analysis of nuclear recombination activating gene 1 (RAG-1) revealed that each species had species-specific alleles. The phylogenetic analysis indicated that alleles in Tango loach were divided into two clusters and those from Ohshima loach formed a single cluster. There were no discrepancies in the combination between mtDNA and nuclear DNA species types within each specimen. DNA fingerprinting analysis (AFLP) showed that the species-unidentifiable individuals exhibited distinctly segregated genetic groups corresponding with Tango and Ohshima loaches. In summary, no hybrids were detected from among any unidentifiable individual examined in this study. New conventional genetic method for discriminating the two sympatric loach species developed here can be effective tool for the conservation of the Tango loach since there was no strict diagnostic morphological character between them.  相似文献   

7.
8.
Prior to this study, the genus Heraeus Stål, 1862 included 14 species, all of which are restricted to the Western Hemisphere. Three species are known from the Nearctic Region, nine from the Neotropical Region, and two mainly tropical elements are distributed in both regions. In this contribution, we consider Heraeus cincticornis Stål, 1874 a junior synonym of Heraeus elegans (Walker, 1873), select a lectotype for Heraeus coquilletti Barber, 1914, and neotype for Lygaeus triguttatus Guérin‐Méneville, 1857, and describe 28 new species. In addition, the two new genera, Baranowskiobius gen. nov., to include H. elegans (Baranowskiobius elegans comb. nov.) and two new species, and Paraheraeus gen. nov., to include Heraeus eximius Distant, 1882 (Paraheraeus eximius comb. nov.), are described. Previously described species and new taxa are (re)described and illustrated, including male genitalia. Scanning electron micrographs, general habitus photographs, and distribution maps are included for all species studied. A phylogenetic analysis comprising 46 terminal taxa and 50 morphological characters was performed, and five species groups were hypothesized, including the coquilletti, caliginosus, guttatus, illitus, and plebejus groups. All known species of Heraeus and the new genera are included in the phylogenetic analysis. The type species of the genera Myodocha Latreille, 1807, Orthaea Dallas, 1852, and Paisana Dellapé, 2008 are used as out‐groups.  相似文献   

9.
10.
Morphological and DNA data show that effused representatives of the Auriculariales (Basidiomycota) with sphaeropedunculate basidia belong to eleven genera of which seven are dealt with in this study. Among them, Myxarium is the largest genus containing 21 accepted species of which nine are reintroduced below and five are described as new. Protodontia is limited to three species only, P. subgelatinosa (the generic type) and two newly described species from Africa. Protoacia is a new monotypic genus for P. delicata, sp. nov., widely distributed on coniferous hosts in Eurasia. Myxariellum is erected for two new species with smooth hymenophore from northwestern North America while Gelacantha is introduced for G. pura, a new species with hydnoid hymenophore from Caucasus. Our data do not confirm the present synonymy of Sebacina sphaerospora with Tremella glaira, and these species are placed in two separate genera – Hydrophana, gen. nov., and Ofella, gen. nov., respectively. A key to European Myxarium and similar‐looking species is included.  相似文献   

11.
瑞香属和荛花属为瑞香科瑞香亚科的落叶或常绿灌木,中国西南部是瑞香属和荛花属的重要分化中心。全世界共有瑞香属95种、荛花属70种,中国分布有瑞香属52种、荛花属49种。瑞香属和荛花属的分类学研究一直存在不同程度的分歧。花盘形状和果实类型在传统分类中一直是区分瑞香属和荛花属的典型特征,而花盘形态和果实类型在2个属中存在交叉和过渡,部分植物分类学家根据这些特征将两个属进行过不同程度的归并。该研究采用数量分类法对瑞香属77种(变种)和荛花属62种(变种)植物,选取32个形态学性状进行聚类分析和主成分分析。结果表明:聚类分析和主成分分析均显示两属均未形成单系类群。在主成分分析中,前3个主成分分析的贡献值为35.56%,传统分类中用来区分两属的花盘形状、叶序及果实类型等特征对前3个主成分贡献相对较小,因此,传统分类学中对这两个属进行区分的性状并没有典型的分类学意义。同时,聚类图和主成分分析得到的散点图均不能将这两个属区分开来。数量分类研究结果显示两属植物存在明显的交叉,支持瑞香属和荛花属不是两个独立自然类群的观点。  相似文献   

12.
The Meiglyptini comprise eight species of woodpeckers grouped into three genera, two of which contain three species ( Meiglyptes and Mulleripicus), while one genus includes two species ( Hemicircus). The purpose of this study is to describe the mandibular apparatus found in six species of Meiglyptini and to compare them with each other and with other woodpecker species. The results reveal a number of structures that are worth mentioning: (i) the components of the external mandibular adductor system of Hemicircus concretus, particularly the M. adductor mandibulae externus caudalis medialis, are underdeveloped compared with the other investigated species; (ii) the muscles of the internal mandibular system are structurally different among Meiglyptes species and are less developed, both in size and in structure, in H. concretus; (iii) the M protractor quadrati is vestigial in Meiglyptes species; (iv) the muscles of the protractor system of the quadrate are relatively undeveloped in H. concretus; (v) most of the muscles of the pterygoideus system are structurally differentiated in Meiglyptes species. It appears that the complexity of the mandibular apparatus is associated with the type of food consumed, as the apparatus of the frugivorous species H. concretus is markedly different from that of the insectivorous species.  相似文献   

13.
In a survey on heterostigmatic mites (Acari: Prostigmata: Heterostigmata) associated with insects including ants in northwestern Iran, two new species of myrmecophilous mites of the genus Scutacarus (Acari: Scutacaridae) were found. They are S. shajariani sp. nov. phoretic on Tetramorium sp. (Hymenoptera: Formicidae) and S. ebermanni sp. nov. phoretic on Messor sp. The mentioned new species belong to groups of species with reduced setae e and h2, and no setae 4b, respectively. These two new species are described and illustrated, and world keys are provided for respective species groups.  相似文献   

14.
In a previous study on wild populations of Pyropia, the occurrence of two possible new species (Pyropia sp. 2 and Pyropia sp. 3) which are closely related to the two commercially important Pyropia species, P. yezoensis and P. tenera, was confirmed as the result of molecular phylogenetic analyses. To characterize the morphological features of the two wild Pyropia species, we collected Pyropia blades in a natural population in which Pyropia sp. 3 was known to occur, and carried out molecular identification before detailed morphological observations. Through the molecular identification we found, unexpectedly, that Pyropia sp. 2 blades grew sympatrically in the same site. Therefore, after molecular identification, we examined in detail the external morphology and anatomy of the two wild Pyropia species using more than 10 blades each. As a result, it is concluded that all of the blades of the two species are morphologically identical to P. yezoensis, but distinct from P. tenera. It is therefore considered that both of the two wild Pyropia species are cryptic species within the P. yezoensis complex. Furthermore, this study revealed that the two cryptic species grew sympatrically, even on the same rocks within the natural habitat.  相似文献   

15.
The genus Triticum L. includes the major cereal crop, common or bread wheat (hexaploid Triticum aestivum L.), and other important cultivated species. Here, we conducted a phylogenetic analysis of all known wheat species and the closely related Aegilops species. This analysis was based on chloroplast matK gene comparison along with trnL intron sequences of some species. Polyploid wheat species are successfully divided only into two groups – Emmer (sections Dicoccoides and Triticum) and Timopheevii (section Timopheevii). Results reveal strictly maternal plastid inheritance of synthetic wheat amphiploids included in the study. A concordance of chloroplast origin with the definite nuclear genomes of polyploid species that were inherited at the last hybridization events was found. Our analysis suggests that there were two ancestral representatives of Aegilops speltoides Tausch that participated in the speciation of polyploid wheats with B and G genome in their genome composition. However, G genome species are younger in evolution than ones with B genome. B genome-specific PCR primers were developed for amplification of Acc-1 gene.  相似文献   

16.
Cryptic species are rarer than their combined, morphologically recognisable species. Each cryptic species may have its own habitat requirements and distribution, and each should be considered separately in biodiversity conservation. This investigation explores how well the two cryptic species of the wetland moss Hamatocaulis vernicosus (Mitt.) Hedenäs s.l., included in Annex II of the EU Habitat Directive, are safeguarded in existing protected sites in Sweden. Further, the northern distribution limit of the southern of the two cryptic species is explored. The distributions of the two cryptic species and their intraspecific variation are judged by the nuclear ITS1?+?2 and the two chloroplast markers rpl16 and trnL-trnF for a set of 89 specimens. The genetic differences between the two cryptic species are significant, but there are no differences between the protected and non-protected subsets within the respective species. The protected areas therefore represent these two species’ genetic variation well. The populations of both cryptic species appear stable, according to their genetic signals. One of the two cryptic species occurs almost throughout Sweden, whereas the other occurs only to the south of the southern limit of the southern boreal zone, except for two finds slightly further north in climatically mild areas.  相似文献   

17.
《Journal of bryology》2013,35(2):137-146
Abstract

Epiphytic bryophytes were studied on two tree species with different bark characteristics (Alnus glutinosa and Carpinus betulus) in two vertical ranges (0–60 and 60–200 cm height above ground on the trunk) in a stream valley in the Carpathian Basin (N.W. Hungary). There is a significant difference in the species composition of the trees. Dicranum montanum and Platygyrium repens occurred significantly more often on Alnus glutinosa, whereas Frullania dilatata and Radula complanata were more often on Carpinus betulus in both vertical ranges. Orthotrichum species were typical only in the vertical range 60–200 cm on Carpinus betulus, whereas Plagiothecium nemorale and Metzgeria furcata were typical of Alnus glutinosa and Carpinus betulus, respectively, in the vertical range 0–60 cm. Although most of the bryophyte species have significant phorophyte preferences, Hypnum cupressiforme (in both vertical ranges) and Isothecium alopecuroides (in vertical range 0–60 cm) are indifferent in this respect. Our findings showed clearly that phorophyte preference and vertical position on the trunk are not independent variables. We investigated the independence of the frequencies and abundances of bryophyte species in the two vertical ranges separately on the two tree species. The species form four different groups: (1) species with greater abundance in the higher vertical range; (2) species with smaller abundance in the higher vertical range; (3) indifferent species with nearly uniform abundances in both vertical ranges; (4) species present only in one vertical range. It was found that even a single bryophyte species can show different vertical preferences depending on tree species. No significant relationships were found between the abundances of bryophytes and distance from the stream, slope of the bark surface and trunk circumference. Species-specific traits appear to explain individual phorophyte preferences; however, in several cases chemically mediated effects of the bark appeared to be important.  相似文献   

18.
Aim The aims of this study were (1) to investigate whether the two growth forms of Darwiniothamnus Harling (Asteraceae) originated from the colonization of a single ancestor, (2) to identify the closest relative(s) of Darwiniothamnus, and (3) to review molecular phylogenies from other plant groups to infer the origin of Galápagos endemics. Location Darwiniothamnus is endemic to the Galápagos Islands. Methods All putative relatives of Darwiniothamnus plus 38 additional species were included. Nucleotide sequences of the internal transcribed spacers of the nuclear ribosomal DNA were used for Bayesian and parsimony analyses. Results Darwiniothamnus is polyphyletic. Two species (D. lancifolius (Hook. f.) Harling and D. tenuifolius (Hook. f.) Harling) are woody shrubs that usually grow to 1–2 m in height; they belong to a clade composed of species otherwise restricted to the Caribbean. These two species are sister to Erigeron bellidiastroides Griseb., a herbaceous species endemic to Cuba. The third species (D. alternifolius Lawesson & Adsersen) is a perennial herbaceous plant, woody at the base and reaching only up to 50 cm in height. It is sister to two Chilean (Coquimbo–Valparaiso region) species that also have a perennial herbaceous habit: E. fasciculatus Colla and E. luxurians (Skottsb.) Solbrig. They are placed in an assemblage restricted to South America. The review of previous molecular phylogenetic studies revealed that two of the endemic genera and endemic species of three non‐endemic genera have their closest relatives in South America. Endemic species belonging to three non‐endemic genera have sister species in North America or the West Indies. One endemic genus and endemic species in three non‐endemic genera have sister taxa with a widespread continental distribution, or their molecular phylogenies yielded equivocal results. Main conclusions The flora of Galápagos has affinities with both North America (including the Antilles) and South America. Darwiniothamnus exhibits both patterns: two species of this genus are sister to a taxon endemic to Cuba, supporting a connection between the Cocos plate and the West Indies; the third species, D. alternifolius, provides a link with the Coquimbo–Valparaiso region, suggesting a biogeographical connection between the Nazca plate and southern South America.  相似文献   

19.
Morphological, behavioural and biochemical characters of 9 cosmopolitan, benthic species of the nemertean genus Lineus are used both to clarify their taxonomy and to discuss their phylogenetic relationships. Data analysis shows that all fissiparous species of Lineus collected in the world seas up to date can be placed in a single species, L. sanguineus, with three recognisable subspecies, L. s. sanguineus, L. s. nigricans and L. s. pseudolacteus. These taxa were originally described as separate species mainly according to their geographic origin under the names L. sanguineus (shores of European seas), L. socialis (Atlantic North American shores), L. vegetus (Pacific North American shores), L. pseudolacteus (shores of the English Channel) and L. nigricans (Mediterranean coasts of Italy and France). Examination of the character value matrix suggests a phylogenetic tree developing from two ancestral branches. The first branch includes the two related species L. ruber and L. viridis, the second branch the three species L. longissimus, L. lacteus and L. sanguineus. This approach to the taxonomic and phylogenetic relationships of Lineus nemertean species is in agreement with the intra- and interspecies histocompatibility data in nemerteans: (i) grafts transplanted from donors to recipients of the same species succeed and grafts transplanted from donors to recipients of different species fail; (ii) grafts are rejected more rapidly when the donor and recipient species diverged earlier in evolution and, a contrario, grafts are accepted better when the donor and recipient species have been more recently isolated.  相似文献   

20.
The calanoid copepods of the Nile system   总被引:3,自引:3,他引:0  
At least 11 or 12 calanoid taxa occur in the Nile system. One species is typical of the river and of Lake Chad (Th. galebi); two are restricted to Lake Victoria (Th. galeboides, T. stuhlmanni), but both might be only subspecies to more widespread species. One is restricted to Lakes Edward and George (T. worthingtoni) but is a little known species. No calanoids are on record from Lakes Albert and Kyoga, while the species reported from Lake Turkana (T. banforanus) is out of range, and almost certainly represents an erroneous record. Among the remaining species, four are East-African, ranging from the southern tip of the continent to the Ethiopian plateau and the Nile valley (P. schultzei, Th. mixtus, T. kraepelini, T. cf orientalis), while two are Sahelian species that span Africa from east to west (M. mauretanicus, T. processifer et ssp.).Two new synonyms are introduced. One new subspecies (T. processifier friedae) is described from the Ethiopian plateau. It is suggested that Tropodiaptomus orientalis (Brady, 1886), the type species of its genus, should not be considered a nomen dubium, but should be redescribed on its type female(s) and on topotypical males from Sri Lanka.  相似文献   

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