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1.
PER SUNDBERG 《Zoological Journal of the Linnean Society》1989,97(1):57-68
A phenetic classification based on overall morphological similarity between the species in the family Plectonemertidae (genera Plectonemertes, Campbellonemertes, Potamonemertes, Leptonemertes, Katechonemertes, Argonemertes, Anliponemertes, and Acteonemertes) was undertaken and the result compared with a cladistic and an evolutionary classification. Similarity between species was computed by Gower's general coefficient of similarity and various techniques were used to find patterns in the similarity matrix: single-linkage, average-linkage, and complete-linkage clustering, together with principal coordinate analysis. Although the explicit aim of phenetics is not to estimate the phylogeny, the classification based on overall similarity still portrays phylogeny better than an intuitive assessment of morphological similarity, as judged by the cladistic analysis. The classification does not support the previously proposed hypothesis that the two freshwater genera Campbellonemertes and Potamonemertes have descended from a terrestrial ancestor. 相似文献
2.
Phylogeny and Cladistic Classification of the Paramonostiliferous Family Plectonemertidae (Phylum Nemertea) 总被引:4,自引:0,他引:4
Abstract— Numerical phylogenetic analysis of nemertean species from the genera Plectonemertes, Katechonemertes and Acteonementes (marine), Argonemertes, Antiponemertes and Leptonemertes (terrestrial), Potamonemertes and Campbellonemertes (freshwater) in the family Plectonemertidae was carried out with the following aims. (1) To estimate the evolutionary relationships between and among these species. (2) To lest the hypothesis of Moore and Gibson that the analysed freshwater species originated from a terrestrial ancestor. (3) To classify the species in monophyletic genera. The analysis did not confirm the hypothesis that the freshwater habitat has been colonised via land. Instead, it suggests that both terrestrial and freshwater species within this family have evolved from a marine ancestor. The cladogram suggests that Antiponemetes is paraphyletic, and it is combined with Argonemertes to form a monophyletic genus. 相似文献
3.
A. V. Chernyshev 《Russian Journal of Marine Biology》2008,34(4):258-262
Data on the larval development of Quasitetrastemma stimpsoni and Q. nigrifrons are presented. In both species, fertilization is external; the development passes through a free-swimming larval stage, the “hidden larva.” The larva has three pairs of eyes. After settling, the eyes of the second pair fuse with eyes of the first pair or are completely reduced. The basis and stylets are formed in 7–8 days after fertilization. Larvae of Q. stimpsoni settle on day 9–10 after fertilization; and Q. nigrifrons, on day 7–8. 相似文献
4.
5.
PER SUNDBERG 《Zoological Journal of the Linnean Society》1985,85(3):247-266
The applicability of numerical methods to the taxonomy of the Phylum Nemertea is assessed for a group of hoplonemertean species. The classifications obtained from various cluster and ordination methods are evaluated with reference to their predictability, i.e. the number of character or character states that can be predicted about species A knowing that it belongs to class a. 相似文献
6.
P. VORSTER 《Botanical journal of the Linnean Society. Linnean Society of London》1996,121(3):271-280
In the past, the two species of Courtoisina were placed either in Cyperus L., Mariscus Vahl, or in Courtoisia Nees (now Courtoisina Sojak). While these species show undoubted external similarities to both Cypm and Muriscus , they differ by their widely winged glumes and the arrangement of the veins of the glumes. They also differ profoundly from Mariscus and most species of Cypm in anatomical characteristics, and it is concluded that these differences warrant separate generic status. 相似文献
7.
We estimated the phylogenetic position of the pseudosegmented ribbon worm Annulonemertes minusculus to test proposed evolutionary hypotheses to explain these body constrictions. The analysis is based on 18S rDNA sequences and shows that the species belongs to an apomorphic clade of hoplonemertean species. The segmentation has no phylogenetic bearing as previously discussed, but is a derived character probably coupled to the species' interstitial habitat. 相似文献
8.
RAY GIBSON DANIEL E. WICKHAM ARMAND M. KURIS 《Zoological Journal of the Linnean Society》1990,98(2):185-198
A new genus and species of monostiliferoidean enoplan nemertean from Alaska is described and illustrated. The nemertean, Alaxinus oclairi gen. et sp. nov. , was found on the egg mass of a red king crab, Paralithodes camtschatica. 相似文献
9.
R. Contreras-Lichtenberg 《Hydrobiologia》1996,318(1-3):17-23
The characters of the genitalia of the females of Glyptotendipes glaucus (Meigen, 1818), Glyptotendipes pallens (Meigen, 1804), Glyptotendipes paripes (Edwards, 1929), Glyptotendipes gripekoveni (Kieffer, 1913), Glyptotendipes aequalis (Kieffer, 1922), Glyptotendipes barbipes (Staeger, 1839) and Glyptotendipes salinus Michailova, 1987 are described. A key for the identification of these species is given.The taxonomic status of Glyptotendipes aequalis is discussed. 相似文献
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11.
A new genus and species of monostiliferous hoplonemertean, Diopsonemertes acanthocephala gen. et sp. nov., is described from Otsuchi Bay, Japan. Significant anatomical features of the new form include a body wall longitudinal musculature anteriorly divided into inner and outer layers by connective tissue, no pre-cerebral septum, the presence of a thin coat of diagonal muscle fibres between the body wall longitudinal and circular muscle layers in the foregut body region, cephalic retractor muscles derived only from the inner portion of the divided longitudinal muscles and a rhynchocoel more than half the body length. 相似文献
12.
RAY GIBSON F.L.S. DANIEL E. WICKHAM ARMAND M. KURIS 《Zoological Journal of the Linnean Society》1990,98(3):185-198
A new genus and species of monostiliferoidean enoplan nemertean from Alaska is described and illustrated. The nemertean, Alaxinus oclairi gen. et sp. nov. , was found on the egg mass of a red king crab, Paralithodes camtschatica . 相似文献
13.
Masaharu Motokawa 《Journal of Zoology》2004,263(2):147-157
14.
WILHELM FOISSNER THORSTEN STOECK SABINE AGATHA MICAH DUNTHORN 《The Journal of eukaryotic microbiology》2011,58(5):397-415
ABSTRACT. Using nine new taxa and statistical inferences based on morphological and molecular data, we analyze the evolution within the class Colpodea. The molecular and cladistic analyses show four well‐supported clades: platyophryids, bursariomorphids, cyrtolophosidids, and colpodids. There is a widespread occurrence of homoplasies, affecting even conspicuous morphological characteristics, e.g. the inclusion of the micronucleus in the perinuclear space of the macronucleus. The most distinct changes in the morphological classification are the lack of a basal divergence into two subclasses and the split of the cyrtolophosidids into two main clades, differing mainly by the presence vs. absence of an oral cavity. The most complex clade is that of the colpodids. We partially reconcile the morphological and molecular data using evolutionary systematics, providing a scenario in which the colpodids evolved from a Bardeliella‐like ancestor and the genus Colpoda performed an intense adaptive radiation, giving rise to three main clades: Colpodina n. subord., Grossglockneriina, and Bryophryina. Three new taxa are established: Colpodina n. subord., Tillinidae n. fam., and Ottowphryidae n. fam. Colpodean evolution and classification are far from being understood because sequences are lacking for most species and half of their diversity is possibly undescribed. 相似文献
15.
G. H. RUA 《Botanical journal of the Linnean Society. Linnean Society of London》1996,121(3):229-241
Fifty-eight quantitative and qualitative exomorphological characters were recorded on 48 herbarium specimens belonging to rhizomatous species belonging to the genus Poa. These were treated as OTUs and analysed, together with the data from caespitose species treated in a previous paper, using cluster analysis, principal component analyses and stepwise discriminant analyses. The following hypotheses are proposed and discussed. (1) There is no evidence supporting the hypothesis that growth habit characterizes supraspecific entities. (2) P. trivialis, P. secunda, P. subenervis and probably P. compressa seem to be well defined species; those remaining are not discriminated through phenetic analysis. (3) There are no phenetic gaps between the rhizomatous species included in the P. oligeria—P. yaganica-P. chrysantha complex and the caespitose P. hachadoensis it is not clear that this single character supports its segregation. (4) The obscurity of the pattern of the species related to P. pratensis-P. nemoralis is probably explained by the capability of P. pratensis to introgress with taxonomically distant species and by the possibility of seasonal intraindividual variation of some characters. (5) The geographical origin of some species postulated as introduced seems to be doubtful. 相似文献
16.
J. Bastow Wilson Michael G. Daker John P. Savidge 《Plant Systematics and Evolution》1990,172(1-4):51-63
The taxonomy of the genusFumaria has not been considered in detail sincePugsley's work in 1919 ff., and few modern methods have been applied to it. In a phenetic study, 33 populations of 11Fumaria spp. were grown in uniform conditions, and seven morphological characters measured. After re-expression and transformation the data were analysed by cluster analysis and principal components analysis. Alternative analyses did not indicate contradictory taxonomic conclusions. Artificial crosses gave some evidence on interfertility, and suggestedF. occidentalis to be an allopolyploid ofF. bastardii ×F. capreolata.
Pugsley's subsectional classification is supported within sect.Parviflora, but not within sect.Grandiflora. His two sections are seen to be meaningful, but not discrete. 相似文献
17.
NIGEL MAXTED F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1990,102(2):103-122
Morphological data were gathered from 126 herbarium specimens representing ten species of Psophocarpus. Specimens were scored for 29 vegetative, 46 inflorescence, 16 legume and six seed characters. The data were analysed using cluster analysis and ordination and the results used to produce an overall phenetic classification. The proposed classification includes a tenth species recently distinguished, but undescribed by Verdcourt. Keys are provided to the subgenera and sections, as well as the ten taxa recognized and the classification is discussed in relation to previous classifications of the genus. 相似文献
18.
Nemerteans are predators of a wide variety of animals, but little is known of their role as prey for other animals. The presence of toxins in the tissues and secretions of these worms has led to the assumption usually suggested that they are ingested only rarely. However, analysis of a Food Habits Data Base from the United States National Marine Fisheries Service, compiled for fishes collected in the Atlantic Ocean from the Canadian border to Cape Hatteras, North Carolina (1973–1990), showed that nemerteans were recovered from the stomachs of 27 species of fishes in 14 families. They were found in 223 of 26 642 (0.84%) fish stomachs examined in the laboratory, but only in 0.09% of 58 812 fish examined in the field. Among species in the former category, for which 1000 were examined, the winter flounder, Pseudopleuronectes americanus(Walbaum), and the yellowtail flounder, Limanda ferruginea (Storer), had the greatest frequency of nemerteans, 71 of 1545 (4.6%) and 33 of 1045 (3.2%), respectively. These nemerteans were identified as Nemertea, Cerebratulus sp. or Micrura sp., but it is likely that they were all of a Cerebratulus-like type. Nemerteans have also been recorded from the guts of eight additional species (including four additional families) of fishes collected from the western Atlantic Ocean, Gulf of Mexico, eastern Pacific Ocean (Washington, Alaska), North Sea and Indian Ocean off South Africa. The black-bellied plover, Pluvialis squatarola(L.), semipalmated plover, Charadrius semipalmatus Bonapart and the herring gull, Larus argentatus Pontoppidan are the only three species known to feed on nemerteans (Cerebratulus lacteus (Leidy) and Paranemertes peregrina Coe by the black-bellied plover and C. lacteus by the other species). Several species of nemerteans are known to ingest other nemerteans, and several arthropods, a squid, and a few other invertebrates also feed on these worms. On the other hand, careful laboratory studies have shown that some members of the Palaeonemertea, Heteronemertea and Hoplonemertea, when fed to various species of fishes, crustaceans (Astacidea, Anomura, Brachyura and Amphipoda) and a polychaete, were rejected, usually violently. There is a history of using large nemerteans, e.g. Cerebratulus lacteus and Polybrachiorhynchus dayi, as bait by sport fishermen in the United States and South Africa. The incongruity of successfuly using these toxic animals to catch fish is discussed in relation to conclusions on the importance of nemerteans as prey in the marine environment. 相似文献
19.
A new species of the subfamily Barbinae, Tor yingjiangensis, is recognized from Yunnan province, China. It can be distinguished from other Tor species by the following combination of characters: last simple dorsal-fin ray osseous and non-serrated; no forward directed
predorsal procumbent spine; head length considerably longer than body depth; no tubercles on the snout or sides of the face;
18–20 gill rakers on the outside of first gill arch; 24–26 lateral line scales; median lobe of lower lip short, its posterior
margin truncate, not extending to the vertical across the inner corners of the mouth; and the condition of the lower lip consistent
in individuals of different sizes. The new species has been misidentified previously as Tor putitora (Hamilton, F. 1822. An account of the fishes found in the River Ganges and its Branches. Edinburgh & London. 405 pp), which
occurs in the Ganges and Indus River basins. The new species can easily be distinguished from T. putitora by having 3–3.5 (vs. 2.5) scales from lateral line to pelvic-fin origin, shorter caudal peduncle length (13.0% vs. 17.2%
of standard length), lesser body depth (26.4% vs. 24.0% of standard length) and longer caudal peduncle depth (12.0% vs. 10.9%
of standard length), no longitudinal stripe present along side of body, and eyes visible in ventral view of head. 相似文献