Crustaceana

Fryer, Geoffrey

doi: 10.1163/156854099504004pmid: N/A

AbstractA recent phylogenetic analysis of certain branchiopod crustaceans has many defects. It uses many characters of no phylogenetic significance, others whose state is wrongly assessed, and others that are inapplicable to the organisms concerned. Based as it is on such imperfect information, some of its conclusions are unacceptable, though, ironically, some correct associations are made on the basis of incorrect facts. Une analyse phylogenetique recente de certains crustaces branchiopodes presente beaucoup de defauts. Elle utilise beaucoup de caracteres sans signification phylogenetique, d'autres dont l'etat est mal evalue, et d'autres encore qui ne sont pas applicables aux organismes concernes. Fondees sur une telle information imparfaite, certaines de ses conclusions sont inacceptables, encore que, ironiquement, plusieurs associations soient correctes, bien que fondees sur des faits incorrects.

Flores, Augusto; Negreiros-Fransozo, Maria Lucia

doi: 10.1163/156854099504013pmid: N/A

AbstractThe allometric growth of secondary sexual characters in Pachygrapsus transversus is investigated from the 2nd crab stage onward. Clear sexual dimorphism is restricted to abdominal morphology, but ANCOVA analyses showed that chelae become larger in males and the carapace becomes wider in females. Size at the puberty moult in both sexes was estimated using Somerton's computer techniques. Mature II analyses applied to bi-log gonopod length vs. carapace length relationships indicated a puberty moult at 5.0 mm in males. In females, Mature I analyses detected the overlapping growth phase lines in bi-log carapace length vs. abdomen width scatterplots. Fitting the logistic equation provided an estimate of 50% maturity at 5.5 mm. The regression lines separate young and resting individuals from the potentially reproductive females, but they do not separate young from adult crabs. Year-round monthly samples showed that the proportion of small adult-like females is higher during the breeding season. After breeding, females may moult to a young-like morphotype, as observed in controlled laboratory conditions. Moulting to a resting condition splits smaller mature females into different "growth phase" lines. Therefore, estimates of female size at sexual maturity by means of abdomen allometric growth analyses are inadequate in this species. El crecimiento alometrico de los caracteres sexuales secundarios de Pachygrapsus transversus ha sido investigado desde el segundo estadio pos-larval. El dimorfismo abdominal es la unica caracterostica que permite distinguir claramente los sexos, pero los analisis de covarianza aplicados a las regresiones obtenidas demuestran que las quelas se vuelven m as grandes en machos y que el caparazon se vuelve mas ancho en hembras. La talla en que ambos sexos alcanzan la maturidad sexual ha sido estimada atraves de las tecnicas de Somerton. La aplicacion del programa Mature II a la regresion bi-log entre el largo del caparazon y el largo del gonopodo indica que la muda de la pubertad de los machos ocurre a los 5,0 mm. En las hembras, el programa Mature I detecto la sobreposicion de loneas de regresi on en los diagramas de dispersion de la regresion bi-log entre el largo del caparazon y el ancho del abdomen. Del ajuste de la ecuacion logostica se obtiene que 50% de las hembras son sexualmente adultas a los 5,5 mm. Estas rectas de regresion separan las hembras con potencial reproductivo de los indivoduos j ovenes y aquellos en reposo sexual. Sin embargo, las rectas no separan jovenes de adultos. Muestreos mensuales a lo largo de un ano indican que la proporcion de hembras de talla puberal con morfologia adulta es mas elevada durante el peroodo reproductivo. Despues de la reproduccion, estas hembras pueden obtener en la siguiente muda una condicion morfologica semejante a la joven, como fue verificado en condiciones de laboratorio controladas. La obtencion del reposo sexual divide a las hembras de talla puberal en rectas de regresion distintas, por lo que las estimativas de talla a la maturidad sexual atraves del analisis del crecimiento alometrico del abdomen son inadequadas para esta especie.

Hryniewiecka-Szyfter, Zofia; Gabala, Elzbieta; Babula, Adam

doi: 10.1163/156854099504022pmid: N/A

AbstractUltrastructural observations show that in Saduria entomon (L., 1758) sperm bundles are organized already in the testis, and that a crucial function in this process is played by Sertoli cells, whose protrusions are connected with maturing spermatids. The specific arrangement of maturing spermatids around a Sertoli cell protrusion and their turned-out tails lying centrally in channels reflect the arrangement of spermatozoa in a later bundle. One might assume, therefore, that the pattern along which sperm bundles are organized, which results from their specific structure, is made possible by the way in which the lumen of the testis is penetrated by protrusions of the Sertoli cells. A further role of the Sertoli cells is to produce and secrete matrix components and precursor material for extracellular tubules. Both structures are permanent elements of sperm bundles in isopods. In S. entomon extracellular tubules have a diameter of 80 nm, and their assembling proceeds in close contact with the membrane of a Sertoli cell protrusion. Des observations ultrastructurales montrent que, chez Saduria entomon (L., 1758), les masses spermatiques sont deja organisees dans le testicule et qu'un role crucial dans le processus est joue par les cellules de Sertoli, dont les protrusions sont connectees avec les spermatides en maturation. L'arrangement specifique de ces dernieres autour d'une protrusion de cellule de Sertoli et de leurs queues retournees en position centrale dans les canaux reflete l'arrangement des spermatozoodes dans une masse ulterieure. On peut de ce fait presumer que le modele suivant lequel les masses spermatiques sont organisees, et qui resulte de leur structure specifique, est rendu possible par la facon par laquelle les protrusions des cellules de Sertoli penetrent le testicule. Un autre role des cellules de Sertoli est de produire et de secreter les composants de la matrice et le materiel precurseur pour les tubules extracellulaires. Les deux structures sont des elements permanents des masses spermatiques chez les isopodes. Chez S. entomon, les tubules extracellulaires ont un diametre de 80 nm, et leur assemblage s'effectue en etroit contact avec la membrane d'une protrusion de cellule de Sertoli.

Guiasu, Radu Cornel; Dunham, David

doi: 10.1163/156854099504031pmid: N/A

AbstractDuring contests between evenly size-matched Cambarus bartonii bartonii crayfish males of reproductive form (Form I), the eventual winners performed significantly more total initiation acts, Lunge and Claws Raised initiation behaviours than the eventual losers. There were no significant differences between the numbers of Ambivalent Contact initiation acts and tail flip escape behaviours, respectively, performed by the winners and the losers. During intraspecific, intra-form contests, C. b. bartonii Form I males used the same three main types of initiation acts as Form I males of the closely related species Cambarus robustus. The highly aggressive Lunge initiation act plays a much more important role in the establishment of the dominant-subordinate relationship in the C. robustus intraspecific, intra-form Form I contests than in the C. b. bartonii contests of the same type. The eventual C. b. bartonii losers were considerably less submissive in the intraspecific contests in comparison to the interspecific contests against C. robustus. The decline in both the number of fights and the time spent fighting, which accompanied the establishment of the dominant-subordinate relationship in the C. robustus intraspecific contests, did not take place during the C. b. bartonii intraspecific contests. Pendant les confrontations entre ecrevisses males de taille assortie de l'espece Cambarus bartonii bartonii, appartenant a la forme reproductive (Forme I), les gagnants eventuels accomplissent de facon significative un plus grand nombre total d'actes d'engagement ("Lunge" et "Claws Raised") que les perdants eventuels. Il n'y avait pas de differences significatives entre les nombres des actes d'engagement "Ambivalent Contact" et de degagement "en coup de queue", respectivement, accomplis par les gagnants et les perdants. Pendant les confrontations intraspecifiques, intraformes, les males de C. b. bartonii utilisaient les trois memes types principaux d'actes d'engagement que les males Forme I de l'espece tres proche Cambarus robustus. L'acte d'engagement hautement agressif "Lunge" joue un role beaucoup plus important dans l'etablissement de la relation dominant-domine dans les confrontations intraspecifiques, intraformes Forme I, chez C. robustus, que dans les confrontations de meme type chez C. b. bartonii. Les eventuels perdants de C. b. bartonii etaient considerablement moins soumis dans les combats intraspecifiques que dans les combats interspecifiques contre C. robustus. Le declin, a la fois dans le nombre des combats et dans le temps passe a combattre, qui accompagnait l'etablissement de la relation dominant-domine dans les rencontres intraspecifiques chez C. robustus, n'intervenait pas pendant les rencontres intraspecifiques chez C. b. bartonii.

Lembo, Giuseppe; Silecchia, Teresa; Carbonara, Pierluigi; Acrivulis, Alessandra; Spedicato, Maria

doi: 10.1163/156854099504040pmid: N/A

AbstractThe spatial distribution of the abundance indices of the deep-water rose shrimp Parapenaeus longirostris was investigated applying geostatistical techniques on data collected in the central southern Tyrrhenian Sea from bottom trawl surveys carried out in the autumn since 1994. Experimental variograms (auto and cross) were constructed on the variable "abundance index", expressed in kg/km2, and those variogram models best describing the spatial continuity were detected and validated by the jackknife technique. The spatial structure of the "abundance index", exhibiting a similar pattern throughout the surveys, was described by a spherical model and characterized by a spatial continuity at a small scale level in the whole area. The linear geostatistical approach was applied by different kriging techniques and the estimates extended to the spatio-temporal dimension, in this case adopting the co-regionalized models and applying the cokriging technique. This method applied to the spatial dimension (abundance index and depth). Also, linking the spatial and temporal dimension of the abundance indices, measured in two different years, contributed to represent a more accurate picture of the abundance distribution, and allowed the detection of a temporal persistence of the localization of areas with higher abundance, reducing the standard deviation of the estimation error. This information, if coupled with an analysis of the geographical allocation of the fishing effort, could be of importance in stock assessment, allowing some variant application of the composite surplus production models. La distribution spatiale des indices d'abondance de la crevette rose d'eau profonde Parapenaeus longirostris a ete etudiee en appliquant les techniques de la geostatistique aux donnees collectees dans le centre-sud de la mer Tyrrhenienne au cours des campagnes de chalutage demersal realisees pendant l'automne, depuis 1994. Les variogrammes experimentaux (auto et cross) ont ete construits sur la variable "indice d'abondance", exprimee en kg/km2, et les modeles de variogramme decrivants le mieux la continuite spatiale ont ete determines et valides par la technique du "jackknife". La structure spatiale de l'indice d'abondance a presente le meme aspect pour tous les echantillonages; elle a ete decrite au moyen d'un modele spherique et caracterisee par une continuite spatiale a petite echelle dans toute la zone. La geostatistique lineaire a ete appliquee en utilisant differentes techniques du krigeage, et les estimations ont ete etendues a la dimension spatio-temporelle en appliquant les modeles coregionalises et la technique du cokrigeage. Cette methode, appliquee soit dans la dimension spatiale (indice d'abondance et profondeur), soit dans la dimension spatio-temporelle en considerant l'indice d'abondance echantillonne en deux annees differentes, a contribue a representer une image plus precise de la distribution de l'abondance, et a permis de detecter une persistance temporelle de la localisation des aires a plus grande abondance, en reduisant l'ecart type de l'erreur d'estimation. Cette information, avec l'analyse de l'allocation geografique de l'effort de peche, pourrait etre importante dans l'evaluation des stocks, en permettant l'application, avec quelques variantes, des modeles composites de production.

doi: 10.1163/156854099504059pmid: N/A

doi: 10.1163/156854099504068pmid: N/A

doi: 10.1163/156854099504077pmid: N/A