Hybridisation between introduced and native species is an increasingly important issue concerning environmental stakeholders because it decreases genetic integrity of native stocks. However, hybridisation could also happen between non-native species even if these species belong to different genera. Our study illustrates this particular aspect of alien species invasion with the attempt of artificial hybridisation between sunbleak Leucaspius delineatus and topmouth gudgeon Pseudorasbora parva, both recent additions to the freshwater fish fauna of England. The crossed fertilisation of L. delineatus ova with P. parva sperm lead to viable eggs with a very high hatching rate of 86% although hybrids failed to develop beyond the 1st larval step. Early morphological development of these hybrids was quantified and compared to the early development of the pure bred species.
The taxonomy of myxosporeans was traditionally dependent solely upon the spore morphological and morphometric data. Intensive reports of intraspecific morphological variation, however, are increasingly challenging the taxonomic approaches for myxosporeans. In the present work, the morphological pleomorphism of myxospores of Myxobolus drjagini (Akhmerov, 1954) was observed. More interestingly, all of these pleomorphic myxospores occurred in the same plasmodium of M. drjagini, which refutes the previous hypothesis that morphological variation of M. drjagini was derived from its responses to differences in nutrition and immunological responses associated with different host tissues. Bearing the intraspecific morphometric and morphotype variation in mind, the combination of morphological, ecological and molecular data should be applied to the species identification and delimitation for myxosporeans. This is the first reported myxobolid species with high pleomorphic myxospores which are present in the same plasmodium.
We tested the hypothesis that invasive (IN) species could capture resources more rapidly and efficiently than noninvasive (NIN) species. Two IN alien species, Ageratina adenophora and Chromolaena odorata, and one NIN alien species, Gynura sp. were compared at five irradiances. Photon-saturated photosynthetic rate (Pmax), leaf mass (LMA) and nitrogen content (NA) per unit area, and photosynthetic nitrogen utilization efficiency (PNUE) increased significantly with irradiance. LMA, NA, and PNUE all contributed to the increased Pmax, indicating that both morphological and physiological acclimation were important for the three alien species. Under stronger irradiance, PNUE was improved through changes in N allocation. With the increase of irradiance, the amount of N converted into carboxylation and bioenergetics increased, whereas that allocated to light-harvesting components decreased. The three alien species could adequately acclimate to high irradiance by increasing the ability to utilize and dissipate photon energy and decreasing the efficiency of photon capture. The two IN species survived at 4.5 % irradiance while the NIN species Gynura died, representing their different invasiveness. Ageratina generally exhibited higher respiration rate (RD) and NA. However, distinctly higher Pmax, PNUE, Pmax/RD, or Pmax/LMA were not detected in the two invasive species, nor was lower LMA. Hence the abilities to capture and utilize resources were not always associated with invasiveness of the alien species. and Y. L. Feng, J. F. Wang, W. G. Sang.
In two successive years (2003 and 2004), a set of 16 commercial sugar beet cultivars was established in Randomized Complete Block experiments at two sites in central Greece. Cultivar combination was different between years, but not between sites. Leaf sampling took place once during the growing season and leaf area, LA [cm2], leaf midvein length, L [cm] and maximum leaf width, W [cm] were determined using an image analysis system. Leaf parameters were mainly affected by cultivars. Leaf dimensions and their squares (L2, W2) did not provide an accurate model for LA predictions. Using L×W as an independent variable, a quadratic model (y = 0.003 x2 - 1.3027 x + 296.84, r 2 = 0.970, p<0.001, n = 32) provided the most accurate estimation of LA. With compromises in accuracy, the linear relationship between L×W and LA (y = 0.5083 x + 31.928, r 2 = 0.948, p<0.001, n = 32) could be used as a prediction model thanks to its simplicity. and J. T. Tsialtas, N. Maslaris.
Heteroblasty of sugar beet cultivar Rizor was studied under field conditions for three growing seasons (2003, 2005, 2006) in a Randomized Complete Block (RCB) design experiment. Eleven leaf samplings, from early June till the end of October, were conducted each year and leaf shape parameters [leaf area (LA), centroid X or Y (CX or CY), length (L), width (W), average radial (AR), elongation (EL), shape factor (SF)] were determined by an image analysis system. During samplings, Leaf Area Index (LAI) was measured non-destructively. Significant year and sampling effects were found for all traits determined. With the progress of the growing season, leaves became smaller (LA, L, W, and AR were decreased) and rounded. The largest leaves were sampled in 2006 when LAI was highest. LA was strongly correlated with L and W with simple functions (y = 0.1933 x2.2238, r 2 = 0.96, p<0.001, and y = 28.693 x - 192.33, r 2 = 0.97, p< 0.001, respectively), which could be used for non-destructive LA determination. Also, LAI was significantly related with LA and leaf dimensions (L, W) suggesting that an easy, non-destructive determination of LAI under field conditions is feasible for sugar beet cv. Rizor. and J. T. Tsialtas, N. Maslaris.
Margaritaella gracilis gen. n. et sp. n. (Proteocephalidea: Proteocephalinae) found in the intestine of Callichthys callichthys (Linnaeus) from the Paraná River basin is described. The new genus is placed in the Proteocephalinae because of the medullary position of the genital organs. It differs from all known genera included in the Proteocephalinae by the following combination of characters: 1) scolex with a conspicuous cluster of drop-shaped gland cells posterior to suckers; 2) strobila with a low number of proglottides, all much longer than wide; 3) testes arranged in one field, composed of two parallel rows of testes separated by the uterus; 4) ovary delicate, H-shaped, with branches slender and deeply folliculate at the edges, located at 25-35% from the posterior end; 5) uterus largely extended posterior to the ovary but not reaching the end of proglottis; and 6) vitelline follicles in two narrow lateral bands, largely extended posterior to the ovary. Scanning electron microscopy revealed three types of microtriches on the tegument surface: acicular and capiliform filitriches and gladiate spinitriches. The relative size of the ovary, a character recently used in the systematics of the proteocephalidean cestodes, was calculated for the new species and compared with other species of the group. M. gracilis is the first record of a proteocephalidean cestode parasitizing a callichthyid catfish.
South African clinids are a major component of the temperate intertidal regions that are also known to participate in life cycles and transmission of several groups of parasites. However, the knowledge of trematode diversity of these fishes is incomplete. In this study, two species of Clinus Cuvier, the super klipfish Clinus superciliosus (Linnaeus) and the bluntnose klipfish Clinus cottoides Valenciennes, were collected from six localities along the South African coast and examined for the presence of trematodes. Metacercariae of Cardiocephaloides Sudarikov, 1959 were found in the eye vitreous humour and brain of C. superciliosus and in the eye vitreous humour of C. cottoides. Detailed analyses integrating morphological and molecular sequence data (28S rDNA, ITS2 rDNA-region, and COI mtDNA) revealed that these belong to two species, Cardiocephaloides physalis (Lutz, 1926) and an unknown species of Cardiocephaloides. This study provides the first report of clinid fishes serving as intermediate hosts for trematodes, reveals that the diversity of Cardiocephaloides in South Africa is higher than previously recorded, and highlights the need for further research to elucidate the life cycles of these trematode species. The broad geographical distribution of Cardiocephaloides spp. was confirmed in the present study based on molecular sequence data. The host-parasite interactions between clinid fishes and metacercariae of Cardiocephaloides are yet to be explored.
Czech morphological dictionary developed originally by Jan Hajič as a spelling checker and lemmatization dictionary. Currently it contains full morphological information for each covered wordform, as well as some derivational, semantic and named entity information.
MorfFlex CZ 2.0 is the Czech morphological dictionary developed originally by Jan Hajič as a spelling checker and lemmatization dictionary. MorfFlex is a flat list of lemma-tag-wordform triples. For each wordform, full inflectional information is coded in a positional tag. Wordforms are organized into entries (paradigm instances or paradigms in short) according to their formal morphological behavior. The paradigm (set of wordforms) is identified by a unique lemma. Apart from traditional morphological categories, the description also contains some semantic, stylistic and derivational information. For more details see a comprehensive specification of the Czech morphological annotation http://ufal.mff.cuni.cz/techrep/tr64.pdf .
Taxonomic analyses of four Sabanejewia balcanica populations from Croatia included morphological (morphometric, meristic, phenotypical) and mitochondrial DNA analyses. Comparative analyses of 24 morphometric characters revealed some differences between populations. The specimens from the Drava River are significantly larger than specimens from other populations, whereas the individuals from the Voćinska River represent the smallest European S. balcanica specimens. Due to similarities in morphometric ratios, in the Tree Diagram of Euclidean distances, the Drava and Petrinjčica Rivers populations formed a separate cluster, while the populations from the Rijeka and Voćinska Rivers formed a second cluster. These morphometrical differences are also corroborated by t-test results. Differences among fishes from different populations also exist in external morphology characters, such as spots on the caudal peduncle and the position of the suborbital spine. Mitochondrial DNA analyses enabled us to infer the phylogenetic placement of four Croatian populations within the genus Sabanejewia. All Croatian samples clustered within the two sublineages of the Danubian-Balkanian complex. Samples from the Voćinska River, as well as one sample from the Drava River were included in the “S. balcanica” (VI) sublineage. The remaining samples, including the two remaining haplotypes from the Drava River, were comprised within “S.montana-S.bulgarica-S.balcanica” (III) sublineage.