Acanthocephalan infections in Atherina boyeri (Pisces: Atherinidae) from Tirso.

Infections by the acanthocephalan Telosentis exiguus (Von Linstow, 1901) and another unknown acanthocephalan were studied in the sand smelt Atherina boyeri (Risso, 1810) from the Tirso River mouth in Sardinia. Only a few specimens of T. exiguus (1 male and 2 cystacanths) were found in the host digestive tract; some larvae of an unidentified acanthocephalan encysted in the liver of A. boyeri were also found and are described.     

Phylogenetic relationships of Atherina hepsetus and Atherina boyeri (Pisces: Atherinidae) populations from Greece, based on mtDNA sequences

The genetic divergence and the phylogenetic relationships of six Atherina boyeri (freshwater and marine origin) and five Atherina hepsetus populations from Greece were investigated using partial sequence analysis of 12s rRNA, 16s rRNA and control region mtDNA segments. Three different well divergent groups were revealed; the first one includes A. boyeri populations living in the sea, the second includes A. boyeri populations living in the lakes and lagoons whereas the third one includes all A. hepsetus populations. Fifty-seven different haplotypes were detected among the populations studied. In all three mtDNA segments examined, sequence analysis revealed the existence of fixed haplotypic differences discriminating A. boyeri populations inhabiting the lagoon and the lakes from both the coastal A. boyeri and the A. hepsetus populations. The genetic divergence values estimated between coastal (marine) A. boyeri populations and those living in the lagoon and the lakes are of the same order of magnitude as those observed among coastal A. boyeri and A. hepsetus populations. The results obtained by different phylogenetic methods were identical. The deep sequence divergence with the fixed different haplotypes observed suggests the occurrence of a cryptic or sibling species within A. boyeri complex.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 151–161.     

Histopathology in Atherina boyeri (Pisces: Atherinidae) resulting from infection by Telosentis exiguus (Acanthocephala)

The histopathology developing in the sand smelt Atherina boyeri Risso 1810 from Northern Italy as the result of a natural infection by Telosentis exiguus Von Linstow 1901 (Acanthocephala) was studied and described. Microscope examination of sections of intestinal tissues showed that the parasites did not penetrate through all intestinal layers, and that damage was mostly limited to the epithelium.     

Multilocus phylogenetic analysis of the genus Aeromonas

A broad multilocus phylogenetic analysis (MLPA) of the representative diversity of a genus offers the opportunity to incorporate concatenated inter-species phylogenies into bacterial systematics. Recent analyses based on single housekeeping genes have provided coherent phylogenies of Aeromonas. However, to date, a multi-gene phylogenetic analysis has never been tackled. In the present study, the intra- and inter-species phylogenetic relationships of 115 strains representing all Aeromonas species described to date were investigated by MLPA. The study included the independent analysis of seven single gene fragments (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD), and the tree resulting from the concatenated 4705 bp sequence. The phylogenies obtained were consistent with each other, and clustering agreed with the Aeromonas taxonomy recognized to date. The highest clustering robustness was found for the concatenated tree (i.e. all Aeromonas species split into 100% bootstrap clusters). Both possible chronometric distortions and poor resolution encountered when using single-gene analysis were buffered in the concatenated MLPA tree. However, reliable phylogenetic species delineation required an MLPA including several “bona fide” strains representing all described species.     

Morphological variation in British Atherinids, and the status of Atherina presbyter Guvier (Pisces: Atherinidae)

A series of morphometric and meristic analyses conducted on specimens of sand smelt, Atherina , from populations around the British Isles, and including classic A. boyeri and A. presbyter forms, has shown that the characteristics variously used in the past to distinguish these two species are invalid. Multivariate analyses showed no significant splitting of the material into two groups which might correlate to these two species; classic A. boyeri and the very large Atlantic coast A. presbyter individuals represent the tails of a continuum of form. From these and published data, it is concluded that the A. boyeri morphology varies under the influence of conditions of temperature and salinity during embryo development, and the isolation of populations maintains comparative morphological distinctions resulting from local selection and random genetic drift.     

On the reproductive biology of the sand smelt Atherina boyeri Risso (Pisces: Atherinidae) and its evolutionary potential

The small, typically estuarine fish Atherina boyeri Risso forms local populations which can differ greatly in their population biology and morphology; this species is viewed as being on the brink of speciation. This analysis of the reproductive strategy shows that A. boyeri can rapidly adapt its life history and morphology to environments ranging from freshwater to polyhaline coastal lagoons and oceanic waters. The optimum strategy is shown to be tied to temperate seasonality: the cold winters act to lengthen the life cycle, and result in cyclic switching of energy between reproduction, somatic growth and fat storage. The adaptability of the fish to a range of environmental characters is viewed as being due to natural selection acting to produce a genotype capable of a flexible phenotypic response. This flexibility is essential for survival in the highly variable inshore/brackish habitat. It is argued that such preadaptive plasticity, coupled with the potential for populations to become isolated, produces ideal conditions for speciation. The importance of the coastal, estuarine and lagoonal environment as a springboard for teleost evolution is discussed.     

Some biological parameters of the Mediterranean sand smelt Atherina (Atherina) hepsetus, Linnaeus, 1758 (Pisces: Atherinidae) from the middle eastern Adriatic (Croatian coast)

Data on the length–weight relationship, age, growth, sex ratio and mortality were analysed for the Mediterranean sand smelt, Atherina (Atherina) hepsetus L. (total = 2805; males = 1258; females = 1547) collected in the eastern middle Adriatic island area during the reproductive period (February to April) in 2002. The total length of sampled specimens ranged from 3.8 to 14.5 cm and the weight from 0.28 to 22.39 g. The overall sex ratio was 1.23 : 1 in favour of females, significantly different from the expected 1 : 1 ratio (χ² = 29.76; P < 0.05). All individuals >13.4 cm were females. The oldest collected male and female specimens were 5 years old. The von Bertalanffy growth formula was estimated for females (L_∞ = 15.79 (1−e^{−0.43(t+0.049)}) and males (L_∞ = 15.25 (1−e^{−0.43(t+0.018)}). The power values (b) of the length–weight relationship were very similar for both sexes (b = 3.14) and indicated a slightly allometric growth. The instantaneous rates of mortality for all collected fish were Z = 1.44 year⁻¹; M = 0.94 year⁻¹ and F = 0.50 year⁻¹. The exploitation ratio was E = F/Z = 0.35. The value for M is highly uncertain, however, as well as those values for F and E.     

Age and Growth of Atherina Atherina boyeri (Atherinidae) from Southwestern Crimea (Black Sea)

Journal of Ichthyology - The size and age structure and growth of Atherina boyeri from southwestern Crimea were studied. The ratio of males and females was 1.00 : 1.38, the proportion of males...     

多基因联合分析棒束孢属Isaria（Ascomycota,Cordycipitaceae）系统发育关系

对棒束孢属Isaria及近缘属物种开展5基因（nrSSU、nrLSU、tef-1α、rpb1和 rpb2）测序并联合分析,结合GenBank相关类群序列,探讨棒束孢属系统发育关系,最终获得95个菌株、58个明确分类群的2-5基因序列。利用MEGA和MrBayes软件进行多基因聚类分析,结果表明棒束孢属多系起源于虫草菌科中,分3个不同分支。A支主要由Isaria cicadae、I. teniupes、I. coleopterorum、I. fumosorosea和I. cateniannulata等组成;B支包括I. poprawkii、I. locustica、I. javanica、I. amoenerosea和I. cateniobliqua;C支仅有I. farinosa。分支间被Cordyceps militaris、C. ninchukispora、C. pruinosa等隔开。棒束孢在形态上,主要以瓶梗基部膨大、尖端变细及孢子呈链状等特征与其他类群分开,但同时也发现有棒状分生孢子梗和单孢子类型。基于节点的分歧时间预测分析,推测棒束孢属首次分化于70Mya,但棒束孢属主要物种形成却在60-55Mya,且3个分支的棒束孢物种为快速同时形成,而后大多数类群表现遗传稳定。同时发现,与Isaria Clade A较近一支有粉被玛利亚霉Mariannaea pruinosa（C. pruinosa无性型）和蛹草蚧霉Lecanicillium militaris（C. militaris无性型）;与粉棒束孢距离最近一支有Akanthomyces aculeatus（C. tuberculata无性型）和L. attenuatum（C. confragosa无性型）,是两个不同的属征分类群,且相互间遗传距离较近。根据棒束孢属及其近缘种属形态特征的复杂性推测,棒束孢属在快速物种形成中,其近缘类群存在一定程度的丢失和选择性演化。     

Atherina punctata and Atherina lagunae (Pisces,Atherinidae), new species found in the Mediterranean sea. 2. Molecular investigations of three Atherinid species

On the basis of morphoanatomical parameters, the sand smelt species (Atherina boyeri Risso, 1810) is viewed as a highly polymorphic complex. In this study, intraspecific sequence variation in a portion of the cytochrome b gene was examined in 88 individuals from Tunisia and France. The correlation between the results of statistical analysis of the sequence data using a variety of tree-building algorithms and morphoanatomical analyses demonstrated the subdivision into three putative species: A. boyeri, which only includes non-punctuated fishes, A. punctata, which corresponds to punctuated fishes and A. lagunae, which corresponds to atherines living in lagoons.     

Atherina punctata and Atherina lagunae (Pisces,Atherinidae), new species in the Mediterranean Sea. 1. Biometric investigations of three Atherinid species

Discriminative canonical analysis of 87 biometric parameters in the marine and lagoon atherinids of 'Atherina boyeri' complex from the Mediterranean Sea helps defining three distinct atherinid groups: marine punctuated, marine unpunctuated and lagoon atherinids. Each atherinid group constitutes a clearly independent original entity. Besides, each one is a more or less heterogeneous group with geographical disparities, characterising specimen collected from France and Tunisia. Concordance of biometric, biochemical and genetic results as well help define two new species of atherinids: Atherina punctata = punctuated marine atherinids, and Atherina lagunae = atherinids living in lagoon environments.     

Karyotype analysis in three species of the genus Chirostoma (Atheriniformes: Atherinidae)

Karyotype analyses of three Chirostoma species, C. estor, C. patzcuaro, and C. jordani from Mexico, are presented. C. estor and C. jordani have both a diploid number of 2N = 48 and a fundamental number of NF = 68, but different karyotype formulae. The co-occurrence of these karyotypes with morphometric and allozymatic primitive features so far reported suggests that the ancestral karyotype of the genus Chirostoma was similar to the one shown by these species. The divergent karyotype of C. patzcuaro (2N = 44 and NF = 44) could be related to its endemism and to the relatively small size of its populations. Received: February 7, 2001 / Revised: September 7, 2001 / Accepted: October 11, 2001     

Reproduction in Odontesthes bonariensis (Atherinidae: Pisces) from north-western Argentina

The spawning biology of silver fish, Odontesthes bonariensis (Cuvier and Valenciennes 1835), from north-western Argentina was studied from monthly captures between November 1997 and March 1999. The spawning period and lengths thereof were analysed using gonadosomatic index (GSI) curves and monthly percentage distributions of maturation stages. A single spawning season with two peaks (late winter and early autumn) within 1 year was identified. Also discussed is the relationship between GSI and Fulton's condition factor K.     

Taxonomic review of the genus Hypoatherina Schultz 1948 (Atheriniformes: Atherinidae)

The marine atherinid fishes of the genus Hypoatherina Schultz 1948 (Atherinidae: Atherinomorinae) were redefined from both morphological and molecular analyses, and eight of the ten included species were redescribed. In the molecular phylogeny, four regions of mitochondrial DNA were analyzed. The results of both trees of maximum likelihood and Bayesian analyses indicated the paraphyly of the former Hypoatherina. “Atherina” valenciennei and “Atherina” woodwardi, both formerly belonging to Hypoatherina, show closer relationships with Atherinomorus duodecimalis and Atherinomorus aetholepis. “Hypoatherina” celebesensis is also apart from the clade including the majority of Hypoatherina species. In contrast, H. panatela, formerly regarded as a member of the genus Stenatherina Schultz 1948, is included in the present Hypoatherina clade. The present molecular phylogeny of the genus Hypoatherina can be supported by morphology. The genus Hypoatherina is redefined by the following combinations of characters: ascending process of premaxilla long and slender, its height more than 2.7 times the maximum width; both anterior and posterior lateral processes of premaxilla narrow and deep, the anterior process almost the same as or slightly deeper than the posterior process; premaxilla not tapering posteriorly; posterior upper margin of dentary with a prominent process; upper posterior limb of dentary with round or somewhat angular posteroventral corner; anterior preopercular ridge with a deep notch just above the corner; anus situated posterior to or slightly anterior to appressed pelvic-fin tip in adults; dorsoventral height of exposed area in the midlateral scale (third) row wide, almost equal to the maximum height of the scale, and almost the same height as scales just above or below the midlateral row. The redefined Hypoatherina includes the following ten species: H. barnesi—widely distributed in the Indo-Pacific; H. gobio (lectotype designated herein)—restricted to the Red Sea; H. golanii—restricted to the Gulf of Aqaba, inner Red Sea; H. klunzingeri—from Mozambique to eastern South Africa; H. lunata—distributed in Japan and Indonesia; H. panatela—from western and central Pacific Ocean; H. temminckii—widely distributed in the Indo-West Pacific (neotype designated herein); H. tropicalis—restricted to the northeastern coast of Australia; H. tsurugae—occurring in Japan and South Korea; and H. uisila—distributed in the western and central Pacific Ocean.     

Morphological phylogenetic analysis of the Africana genus (Nematoda: Heterakidae)

A morphological phylogenetic hypothesis of the relationships among the species of Africana is provided. The phylogenetic analysis suggests that Squamata or Amphibia were ancestral hosts for species of Africana, with dispersal events to Testudinidae; a second transfer to amphibians is also suggested. On the basis of biological data for these parasites and the paleogeographic reconstructions, a South American origin for Africana spp. is indicated, with subsequent dispersal events to Africa. It is further proposed that Chamaleonidae acquired species of Africana after their 'out-of-Madagascar' dispersal events to Africa.     

Reproductive behavior of the Atlantic silverside,Menidia menidia (Pisces,Atherinidae)

Synopsis The spawning behavior of the Atlantic silverside,Menidia menidia, was studied at two sites on the North Edisto River estuary in South Carolina. Prespawning schools moved back and forth along the shoreline as the time of high tide approached. Spawning runs took place in the upper intertidal zone at high tide.Spawning fish deposited their eggs on three types of substrates: 1) the lower stems of cordgrass plants,Spartina alterniflora, 2) detrital mats, and 3) exposed cordgrass roots along erosional scraps. Spawning behavior during egg deposition and fertilization was similar for all three substrates. Females released eggs during a rapid fluttering motion of the posterior half of the body. A similar movement accompanied release of sperm by males. Behavior of fish just prior to spawning insured deposition of gametes at locations that provided protection from thermal and drying stress during development. Eggs were deposited at mean intertidal elevations of 1.8 and 1.5 meters above mean low water (MLW) at respective study sites. They were exposed to the atmosphere for approximately ten hours between successive high tides.During spawning runs in which eggs were deposited at the base of cordgrass plants, ambient dissolved oxygen concentrations of the water in the spawning area were sometimes reduced to < 1.0 mg. 1^–1. Spent fish, apparently incurring an oxygen debt while spawning, formed a nonschooling aggregation offshore from the spawning zone.The recurrent use of specific spawning substrates for egg deposition resulted in an uneven distribution of spawning runs along the shoreline at each study site.Contribution No. 409 to the Gulf Breeze Environmental Research Laboratory. Contribution No. 377 to the Belle W. Baruch Institute for Marine Biology and Coastal Research.     

Biology of the Sand Smelt, Atherina presbyter (Teleostei: Atherinidae), Off the Canary Islands (central-east Atlantic)

Atherina presbyter is a common fish off the Canary Islands. Age, growth, reproduction, and mortality of the species are studied based on sampling carried out from July 1995 to June 1996. The parameters of the total length–total weight relationship are: a=0.004521, and b=3.0771. Otoliths age readings indicate that the sampled population consists of four age groups (0–III years). The von Bertalanffy growth parameters for all individuals are: L=122mm total length, k=0.79year^–1, and t₀=–0.21 years. Individuals grow quickly in their immature first year, attaining approximately 60% of their maximum length. After the first year, the annual growth rate drops rapidly, because the energy is probably diverted to reproduction. It is a gonochoristic species with no evidence of sexual dimorphism. The gonad is present as a single diffuse testis in males and as a single discrete ovary in females. The overall ratio of males to females is not significantly different from 1:1. The reproductive period of the species is protacted (February to June). The peak of the reproductive effort occurs in April–May. The size at first maturity is 68mm. The population is being heavily exploited.     

Preliminary phylogenetic analysis of the fern genus Lomariopsis (Lomariopsidaceae)

A preliminary phylogenetic analysis is presented forLomariopsis based on sequence data from the chloroplast intergenic spacertrnL-trnF. The analysis includes 27 (60%) of the approximately 45 species in the genus. A strict consensus of six most parsimonious trees supports two main clades—theSorbifolia-group and theJapurensis-group—previously proposed based on heteroblastic leaf development. TheSorbifolia-group is entirely neotropical and includes all the Antillean species. The species in this clade had either smooth or crested spores, but the tree was ambiguous whether these spore types define two separate clades. TheJapurensis-group consists of two clades, one primarily neotropical and the other entirely paleotropical. Within the neotropical clade nests a clade of two African species, which have long-spiny spores typical of the neotropical clade and unlike those found in the African-Madagascan clade. The occurrence of these two species in Africa is best explained by longdistance spore dispersal of their ancestral species from the neotropics to Africa. Within the paleotropical clade of theJapurensis-group, a clade of three African species is nested among seven species from Madagascar (all the species from that island). Within the genus as a whole, a derived character—the abortion of the rachis apex and its replacement by the distal lateral pinna assuming a terminal position—was found to have evolved separately in each of the four species with this kind of leaf apex. A scanning electron microcope study of the spores revealed five types, and a transformation series for these different types is proposed. Characters of spore morphology and heteroblastic leaf development agreed with many of the clades in the phylogenetic tree. This study represents the first phylogeny for the genus.     

Age, growth and mortality of a semi-isolated lagoon population of sand smelt, Atherina boyeri (Risso, 1810) (Pisces: Atherinidae) in an estuarine system of northern Greece

Age, growth and mortality of the sand smelt, Atherina boyeri (Risso, 1810), were studied in the Vistonis estuarine system in northern Greece from February 1989 to August 1990. Overall male : female sex ratio was 1 : 2.5, statistically different from unity. Total lengths ranged between 13 and 105 mm. Age determination based on scale readings showed that the population comprised five age‐groups. Sand smelt grew allometrically (b = 3.22) and rapidly during the first year, achieving 60% of their growth. Growth parameters of the population were: L_∞ = 116.97 mm, K = 0.35 year⁻¹ and t_o = −0.99 years. Growth index ϕ′ was 3.69 of all individuals studied. The mean growth index was significantly lower for the Mediterranean lagoon (ϕ′ = 3.73, SD = 0.1) than for Atlantic populations (ϕ′ = 3.92, SD = 0.06). Total mortality rate was Z = 1.29 year⁻¹ and natural mortality M = 0.95 year⁻¹. Males had a lower life span than females, the latter dominating length classes >60 mm. Exploitation rate of the studied population was E = 0.26, suggesting that stock size might increase and generate improved possibilities for exploitation.