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... The reproductive biology of this species has been studied in the Mediterranean and some differences in the spawning season and the size at maturity have emerged in the different areas investigated (e.g. Mangold-Wirz, 1963; Guerra, 1978; Mangold, 1983 Mangold, , 1989 Sanchez & Obarti, 1993; Quetglas et al., 1998; Tirado-Narvaez et al., 2003; González et al., 2011; Cuccu et al., 2013). The available sexual maturity scales used for O. vulgaris are more or less detailed and criteria adopted to divide the different stages depend, in some cases, on the morphologic status of the gonads and/or on other features such as the dimensions of the sexual products (e.g. ...
... In fact, the spawning females were collected from dens as were the spent specimens (stage 6) in which the ovaries contained post ovulatory follicles and atretic cells as a result of the ovulation process. Potential Fecundity estimated in mature females (stage 4) is in agreement with previous studies for Mediterranean and Atlantic specimens (e.g. Mangold, 1989; Silva et al., 2002; Otero et al., 2007), even if we have never analyzed specimens as large as the Atlantic samples (up to 6000 g). The maximum size of the oocytes (4 mm) in mature females is bigger than those reported by several authors (e.g. ...
... In mature males, the maximum number of spermatophores is higher than those reported for other Mediterranean areas (Mangold-Wirz, 1963; Guerra, 1975), similar to that found by Silva et al. (2002) in the Gulf of Cádiz, and markedly lower than that given by Otero et al. (2007) for the Galician waters. Moreover, their lengths are in agreement with Mediterranean literature (Mangold-Wirz, 1963; Mangold, 1983 Mangold, , 1989) and lower than those for the Atlantic (Silva et al., 2002; Otero et al., 2007). Overall, the scales proposed in this study allow easy identification of the different phases of sexual maturation for the two genders of O. vulgaris and could be an important tool to define assessment models for sound management of the species, considering also that environmental variability seems to have an effect on stock fluctuation (e.g. ...
In this paper we report information about the sexual maturity process of 245 Octopus vulgaris specimens (75 females and 170 males) from the Mediterranean Sea. For both sexes, six stages of sexual maturity (immature, developing, maturing, mature, spawning, and spent) are identified on the basis of macroscopic and microscopic observations of the reproductive system and linked with some reproductive indices. A good correspondence between gonad appearance and its histological structure is observed, highlighting, in females, how oviducal gland morphology plays a crucial role in the macroscopic evaluation of maturity. The Gonadosomatic and Hayashi indices, in the two genders, and the Oviducal Gland index in females alone do not allow distinguishing all the stages in an irrefutable way. Data on the potential fecundity, oocyte and spermatophore size are reported and compared with literature. In addition, spermatophore components are also computed. The results reported in this paper lead to easy identification of the different phases of sexual maturation of O. vulgaris and could constitute an important tool for defining assessment models in view of sound management of this species.
... Adis (2002) les estime compris entre 1 250 et 1 500. 1 400 espèces semble être le chiffre le plus raisonnable. Brignoli (1978), Hubert (1979) et Hillyard (1992 Millot (1968b), Kaestner (1968) et Rollard (1991 notent le chiffre de 60 espèces, Hillyard (1992) mentionne 70 espèces d'Amblypyges dans le monde, 100 d'après Dupré (1996) et Schiedjok (1998), et 130 selon MacGavin (2000. Hubert (1979) en propose 770 espèces, ce qui est, à notre avis, une coquille. ...
... De 1 à 3 espèces fossiles suivant Selden (1999). Millot (1968b) en mentionnait déjà 4. ...
The number of Arachnids species recorded in France and in the world (Arthropoda : Arachnida). The species number of Arachnida described in France and in the world is proposed. We mainly focus on the eleven orders still alive today as well as on fossil orders or species.
... Scorpions (Class Arachnida, Order Scorpiones) are chelicerates with an ancient history that have changed little since the Silurian (450 million years) (Millot and Vachon, 1968) and are considered as one of the oldest known terrestrial lineages (Zouari et al., 2006). Therefore, they have been chosen as models to perform biochemical studies as those carried out by Louati et al. (2011) and Zouari et al. (2005) where digestive enzymes were studied, thus allowing for the interpretation of the digestive process in animals with primitive traits. ...
... Features of this mating system share commonalities with L. plei, L. pealeii, L. opalescens and L. forbesi as partially reviewed in Mangold (1989), Hanlon and Messenger (1996) and Hanlon (1998). The mating systems of Loligo show some striking differences with another loliginid, the Caribbean reef squid S. sepioidea (Moynihan, 1985;Hanlon and Messenger, 1996), thus care must be invoked before generalizations are made about loliginid squid mating systems. ...
The chokka squid migrates to coastal waters to spawn, and its behavior on shallow spawning aggregations was analyzed by video sequences taken during SCUBA diving. Most squids were paired (M/F) on the spawning sites, yet mate pairing duration was brief. Near to egg masses, a few lone large males were always present and would fight consort males to obtain access to paired females. Paired 'consort' males won 16 agonistic contests while unpaired 'intruder' males won 9; thus there was a considerable turnover rate for consortships. The larger male won in 14 of the 25 contests. Fighting involved mainly visual signalling but escalated to moderate physical contact (Fin beating) but not injury. Both sexes had multiple mates even within several hours. Two methods of mating were observed, each with different placement of spermatophores, and a third method possibly exists. Large paired males mated in the 'male-parallel' position and inserted spermatophores near the oviduct; egg laying usually occurred shortly thereafter. Small sneaker males were often successful in mating a paired female; they copulated in a modified 'head-head' position in which they attempted to place spermatophores amidst the female's arms. Remarkably, sneakers seemed to recognize when females were holding an egg capsule and then timed their copulation attempt at that time. Sneakers did not engage large male consorts in contests, and consorts seldom chased them away when they mated a female. The 'cuckolded' consorts did not attempt to mate females again before they laid the egg capsule. Males guarded females as they descended periodically to lay individual egg capsules. All of these features indicate a high level of sperm competition. There were no lone females on spawning sites, and all arrived there with stored sperm in the seminal receptacle, having presumably mated in the typical 'head-head' position previously. Females rarely rejected males (consorts or sneakers) and it is possible that they exerted some choice of male sperm. There was no form of parental care of the eggs or paralarvae. Reproductive tactics are discussed in relation to the life cycle of this valuable fishery species.
... In addition, the incompleteness of the fossils, in this case the systematic lack of the head shield and ventral rotation of frontal appendages, are clear indicators of their exuvial nature as previously reported [15]. This state of preservation resembles the “open molt position” of a number of modern decapod crustaceans [21,22], as well as fossil lobsters and other fossil decapods [23,24]. ...
Background
The Burgess Shale is well known for its preservation of a diverse soft-bodied biota dating from the Cambrian period (Series 3, Stage 5). While previous paleoecological studies have focused on particular species (autecology) or entire paleocommunities (synecology), studies on the ecology of populations (demecology) of Burgess Shale organisms have remained mainly anecdotal.
Results
Here, we present evidence for mass molting events in two unrelated arthropods from the Burgess Shale Walcott Quarry, Canadaspis perfecta and a megacheiran referred to as Alalcomenaeus sp.
Conclusions
These findings suggest that the triggers for such supposed synchronized molting appeared early on during the Cambrian radiation, and synchronized molting in the Cambrian may have had similar functions in the past as it does today. In addition, the finding of numerous juvenile Alalcomenaeus sp. molts associated with the putative alga Dictyophycus suggests a possible nursery habitat. In this nursery habitat a population of this animal might have found a more protected environment in which to spend critical developmental phases, as do many modern species today.
... Les céphalopodes sont considérés comme les mollusques les plus sophistiqués des points de vues morphologique, anatomique, physiologique et comportemental (Mangold, 1989;Brusca and Brusca, 2002). Leur capacité natatoire très développée leur permettent de réaliser des cycles migratoires sur des distances importantes, une caractéristique les rapprochant du mode de vie des poissons (Boyle and Rodhouse, 2005). ...
The English Channel cuttlefish Sepia officinalis is the most important cephalopod stock in the N-E Atlantic but is only managed by local measures, mainly due to a lack of suitable tools. The objective of this work is therefore to improve the knowledge of its population dynamic, particularly the parameters influencing the resource abundance. After a summary of the state of the art, in a first step, the exploration of the stock structure during the reproduction period revealed that, in a warming and high fishing pressure context, the life history traits of cuttlefish have changed and a percentage of one year old cuttlefish are mature. In a second step, the influence of the fuel price on the spatial allocation of the French trawling effort was highlighted and this metier is the most suitable to derive cuttlefish abundance indices. In a third step, a two stage biomass model, a suitable model to assess exploited marine populations with poor age data, was developed and enabled the development of two indicators of the fishing impact on the exploited cohort: the stock-recruitment relationship and the exploitation rate. In a fourth and final step, the contribution of 3 spawning areas to the recruitment was explored using 3 different techniques. Results indicate that the central stock is a mix between different spawning areas and seems to be influenced by different environmental and anthropic parameters. Finally, results are discussed in the context of each life cycle phase (reproduction, pre-recruit stage, recruitment and exploitation) and perspectives are presented.
... In contrast to other Arachnida, an endosternite is missing in Solifugae (Firstman, 1973). The dorsal apodeme of coxae II is, instead, in a comparable position (Figure 1c,d) (Firstman, 1973;Kittary, 1848;Millot, 1949;Pocock, 1902;Schimkewitsch, 1895). This apodeme is formed by dorsal processes composed of the dorsal edges of coxae II. ...
The locomotory system of Solifugae is distinct from that of other Arachnida in several ways. Only three pairs of legs are involved in locomotion, while the first pair function as sensory appendages. Morphologically, the proximal region of the locomotory system in Solifugae is characterized by fused coxae. Within the prosoma of Solifugae, an endosternite is missing: in other Arachnida, this endosternite serves as the proximal attachment site for a portion of the extrinsic musculature. How then do these skeletal modifications influence the muscular anatomy in the proximal region of the locomotory system? To answer this question, we studied the skeletomuscular anatomy of Galeodes granti at the interface between the prosoma and legs, reinvestigating the complex muscular anatomy of this body region for the first time in over 80 years and—for the first time—using detailed micro‐computed tomography scans to analyze the skeletomuscular morphology. Specimens of three further species were checked for comparison. The analysis revealed differences in the number and composition of coxa‐trochanter muscles in each of the four pairs of legs. These are compared in the light of serial homology. The comparison between the proximal locomotory system of Solifugae and that of other Arachnida unveils a series of analogies. Primarily, the coxa‐trochanter joint is the most proximal joint to move the leg relative to the prosoma. Therefore, we argue that from a morpho‐functional point of view, the coxa‐trochanter muscles in Solifugae should be considered secondary extrinsic musculature. Thus, the legs gain a stable, articulated joint in the most proximal region of the leg to the prosoma, which might be advantageous for agile locomotion.
... Due to the poor mechanical digestive capacity of cuttlefish, digestion in cuttlefish mainly depends on digestive and hydrolysis enzymes in the intestine and hepatopancreas (Boucaud-Camou and Pequignat 1973;Boucher-Rodoni 1981). Cephalopods showed varied digestive capacities based on the components of the fodder and the stage of development (Mangold and Bidder 1989;Villanueva et al. 2002;Perrin et al. 2004). Thus, we aimed to explore the involvement of various enzymes regarding the digestion and absorption of lipids in S. lycidas fed different lipid levels, which will be very important in developing a reasonable artificial feed for the culture of S. lycidas. ...
The aim of this experiment was to determine the optimal initial food for hatchling cuttlefish and to investigate the influence of dietary composition on the growth, survival, and nutritional composition of cultured juvenile cuttlefish, Sepia pharaonis. Six experimental food groups were designated: Artemia nauplii, Calanus sinicus, frozen Hyperacanthomysis brevirostris, Ampithoe valida, H. brevirostris, and subadult Artemia. The results showed that survival, growth body biochemical composition of juvenile cuttlefish were significantly affected by experimental diets (P < 0.05). The optimum initial food was H. brevirostris, yielding a growth rate as high as 6.39%/d and survival rate reaching 81%. Growth rate was significantly positively correlated with dietary protein, Lys, Met, Phe, Iie, Leu, Trp, Arg, Gly, Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA), and 16:0 (P < 0.05). Survival was significantly positively correlated with dietary protein, Lys, Met, Phe, Val, Thr, Iie, Leu, Trp, Arg, Gly, EPA, DHA, and 16:0 (P < 0.05). The dietary protein, lipid, Met, Val, Thr, Leu, 18:0, and EPA were prone to accumulation within the body of juvenile cuttlefish (P < 0.05). These results demonstrate that juvenile cuttlefish exhibited the best growth rates and survival when fed a diet that supplied high-protein, low-fat, and larger quantities of Lys, Met, Phe, Val, Thr, Iie, Leu, Trp, Arg, Gly, EPA, DHA, and 16:0.
... Due to the poor mechanical digestive capacity of cuttlefish, digestion in cuttlefish mainly depends on digestive and hydrolysis enzymes in the intestine and hepatopancreas (Boucaud-Camou and Pequignat 1973;Boucher-Rodoni 1981). Cephalopods showed varied digestive capacities based on the components of the fodder and the stage of development (Mangold and Bidder 1989;Villanueva et al. 2002;Perrin et al. 2004). Thus, we aimed to explore the involvement of various enzymes regarding the digestion and absorption of lipids in S. lycidas fed different lipid levels, which will be very important in developing a reasonable artificial feed for the culture of S. lycidas. ...
This study was conducted to determine the effects of dietary lipids on the growth performance, muscle composition, and enzyme activities of the stomach, intestines, and liver of Sepia lycidas juveniles. Fish oil and soybean lecithin were selected as lipid sources to formulate six experimental diets containing lipid levels of 3.68, 4.15, 6.62, 8.09, 9.56, and 11.03%. The feed efficiency first declined and then rose, with the lowest value obtained in individuals fed the 8.09% lipid content diet; the protein efficiency ratio significantly decreased with an increased lipid level. The highest crude protein content and lowest crude lipid content were simultaneously obtained in individuals fed the 9.56% lipid content diet. The activities of pepsase, trypsin, and intestine lipase initially increased before decreasing. The highest activities of protease, trypsin, and lipase were obtained in individuals fed the 9.56% lipid content diet, while the highest activity of amylase was obtained in individuals fed the 6.62% lipid content diet. Hepatic glutamate pyruvate transaminase and glutamic oxaloacetic transaminase initially increased and then held steady, with the highest activities simultaneously obtained in individuals fed the 9.56% lipid diet. Our results suggest that dietary lipids at a level of 9.56% could be the optimal lipid requirement for S. lycidas to grow and maintain normal metabolism.
... Voici le catalogue des Esp?ces de France suivant CHAMBERLIN (1929, 1930a, 1930b), BECKER (1881), BELLMANN (2000), BERANGER-LEVEQUE & ROLLARD (1994, 1996, DOIGNON (1976), DRESCO (1947), ELLINGSEN (1908,1912), HARVEY (1990), HEURTAULT (1966, 1968, 1971, 1975, 1976, 1977, 1979a, 1979b, 1980, 1981, 1985, 1990), IORIO (2002IORIO ( , 2003aIORIO ( , 2003b, JEANNEL (1926), JUDSON (1988JUDSON ( , 1990JUDSON ( , 1993JUDSON ( , 1994JUDSON ( , 1996JUDSON ( , 1998a, KOVOOR & MUNOZ-CUEVAS (2000), LAGUARRIGUE (1950, LANCELEVEE (1884), LECLERC (1982,1983), , LOPEZ & MARCOU (1979), LOPEZ & al. (1985), MAHNERT (1988), PERRIER & al. (1929), SIMON (1872SIMON ( , 1879SIMON ( , 1896SIMON ( , 1907 et VACHON (1941VACHON ( , 1945VACHON ( , 1947VACHON ( , 1952VACHON ( , 1954VACHON ( , 1968 Chthonius (Chthonius) ischnocheles Beier, 1932 ;Chthoniuss (sic) ischnochele (sic) Fage, 1933 ;Chthonius (Chthonius) rhodochelatus Hadzi, 1933 ;Chthonius rhodochelatus Roewer, 1937 ; Chthonius reyi (sic) Sanfilipo, Timosi & Conci 1943 ;Chthonius ischnocheles Caporiacco, 1948 ;Chtonius (sic) (Chthonius) ischnocheles Beier, 1949 ; Chthonius ischnochelus (sic) Gilbert, 1951 ;Chthonius (Chthonius) dacnodes Navas, 1954 ;Cthonius (sic) ischnocheles Cloudsley-Thompson, 1959 ;Chthonius ischnocheles Howes, 1972 ; Chthonius iscnocheles (sic) Klausen, 1975 ;Chthonius ischnocheles ischnocheles Callaini, 1980. Il est ? ...
Since SIMON (1879), no catalog of French false-scorpions has been realised. HARVEY’s book (1990) is a list of the world species. This preliminary catalog attempts to draw up an inventory of the French fauna. For more than 3 000 Species in the world, France has more than 125 Species of Pseudoscorpions. Every Species is listed with its taxonomy, its synonymies but also with the detail of its distribution. A record of a fossil species is doubtful. Some Genera names will certainly be reactualized in the future.
The species of the genus Alurnus Fabricius (Coleoptera: Chrysomelidae: Cassidinae) are reviewed. Twenty-three species are recognized as valid. Alurnus bicolor from Colombia and A. crenatus from Bolivia are described as new species. Alurnus costalis dallieri Pic is elevated to full species status. Lectotypes are designated for A. humeralis Rosenberg, A. mutabilis Waterhouse, and A. salvini Baly. The species are redescribed and illustrated, and a key to the species is presented.
As a component of the primate shoulder, the clavicle is expected to reflect locomotor adaptations. Whereas previous work has generally focused on clavicular length and torsion, the shape of clavicular curvature may better distinguish taxa and provide additional information about upper limb use in locomotion. This study uses three-dimensional geometric morphometrics to analyze shape differences in the curvatures of the clavicle in different locomotor groups of anthropoid primates.
Sliding semi-landmarks were placed on clavicles of 10 Anthropoid primate species (total n = 85) that display a range of locomotor behaviors. Landmarks (k = 39) were chosen to capture the overall curvature of the clavicle in three dimensions.
The degree of ventral curvature in the clavicle represents a gradient from most-curved in suspensory genera (e.g., Ateles, Hylobates, and Pongo) to least-curved in genera that are rarely suspensory (e.g., Papio and Gorilla). This curvature may allow an increased range of craniodorsal movement without the clavicle impinging on the thoracic outlet. An inferior curvature of the medial clavicle is found in hominoids and brachiators. This curvature could help stabilize the shoulder and prevent superior dislocation of the clavicle in suspension. Finally, a superior curvature in the lateral part of the clavicle, most pronounced in quadrupedal monkeys, may be related to the relative position of the scapula and sternum.
Patterns of clavicular curvature in anthropoid primates reflect locomotor behavior and successfully distinguished among taxonomic and locomotor groups. In the future, this method could be used to assess locomotor behavior in fossil primates. Am J Phys Anthropol, 2015. © 2015 Wiley Periodicals, Inc.
© 2015 Wiley Periodicals, Inc.
From the last decades of the 19th century to the middle of the 20th century, the name Thysanura was used to include what today are recognized as two independent orders: the Microcoryphia, and the Archaeognatha. Current evidence supports Microcoryphia and Zygentoma as independent monophyletic orders, although the relationships among the families are disputed. This chapter tabulates families and subfamilies in these orders. Knowledge of fossils is essential for understanding the evolution of recent forms, the relationships between recent and fossil groups, and when the various groups began their independent evolutionary histories. The Microcoryphia and Zygentoma contribute to an understanding of the movements of tectonic plates and of paleoecology, allowing interpretations of recent distributions. Representatives of the Microcoryphia and Zygentoma are hosts of unicellular and multicellular endo‐ and ectoparasites. Microcoryphia and Zygentoma are preyed on by scorpions and spiders, Chilopoda, and insects such as the Nabidae and Reduviidae and Coleoptera.
Natural populations of Mediterranean commercial sponges have declined substantially over recent decades.The present study explored the distribution of genetic diversity of the endangered bath sponge Spongia lamella along the western Mediterranean and the Portuguese coast.Seven microsatellite markers were used to genotype 231 individuals scattered over nine populations. Basic genetic descriptors and population genetic analyses based on FST test, analyses of the molecular variance (AMOVA), Bayesian clustering, dissimilarity analysis of principal components, and demographic analyses were performed.Genetic differentiation between populations was large and highly significant (global FST = 0.236, P CT = 0.129, P = 0.003).Restricted gene flow owing to short‐distance larval dispersal and hydrographical barriers may be playing an important role in genetic differentiation.Recent bottlenecks were also detected for most populations of this sponge.The high levels of inbreeding, sub‐structuring, and modest levels of genetic diversity that characterized populations of S. lamella (mean value of genetic diversity 0.512), may compromise its long‐term survival. Only one population, from the Gibraltar Strait, presented high levels of genetic diversity (Ceuta, genetic diversity = 0.657), indicating a hotspot of genetic diversity for this species with special relevance for its conservation.Disease outbreaks and overexploitation may be the most important causes of genetic diversity impoverishment of S. lamella.Future conservation guidelines should focus on preserving genetic diversity within genetically impoverished populations by limiting exploitation, and increasing population size. Transplanting specimens from areas with high values of genetic diversity to areas with low diversity values or to areas that have recently experienced demographic declines could reverse the local and global recession of this species. Copyright © 2014 John Wiley & Sons, Ltd.
Litobothrium aenigmaticum Caira, Jensen, Waeschenbach, & Littlewood 2014 is a cestode species that parasitizes pelagic thresher sharks in Taiwan and the Gulf of California. A previous study using light microscopy suggested the scolex contains four types of unusual tissues, one of which was considered to aid in adhesion of the worm to the mucosa of the spiral intestine. The function of the other tissues was unknown. Also unknown was the function of two laterally paired ducts found extending throughout the length of the worm. The goal of the present study was to use transmission electron microscopy (TEM) to examine the internal anatomy of the scolex and cephalic peduncle of this tapeworm in more detail. Three specimens from Taiwan were examined with TEM and two with light microscopy. Transmission electron microscopy revealed that the laterally paired ducts were excretory, since they were closely associated with numerous protonephridia. The number of cell types, previously referred to as tissues, in the scolex was expanded to 11 based on a combination of features including cell size, nucleus size, ratio of the maximum diameter of the nucleus to maximum diameter of the whole cell, and types of observed organelles, as well as the presence or absence of cytoplasmic electron-dense and electron-lucent vesicles. The cytoplasm of all 11 cell types was found to include electron-dense vesicles, and all types were periodic acid-Schiff (PAS) positive. This suggests that the electron-dense vesicles may contain glycoproteins and/or mucoproteins. As all 11 cell types occurred within the region of the scolex that is surrounded by a papilla of host mucosa at the site of tapeworm attachment, we hypothesize that one or more of these cell types may produce a substance that induces this inflammatory reaction. The specific products in the secretory vesicles and how those products are released are still unclear, as are any relationships between or among the cell types in terms of products produced. Further research will be necessary to fully understand the complexity of this organism.
The midgut of Cryptocellus boneti was studied by light and electron microscopy. The epithelia of the diverticula and of the anterior part of the midgut tube are composed of two cell types: digestive and secretory. In contrast, the epithelia of posterior part of the midgut tube and of the stercoral pocket consist of one type of cells only. In some places, parts of the midgut system are connected by an intermediate tissue. Digestive cells are characterized by an apical system of tubules, nutritional vacuoles, and spherites; characteristic features of secretory cells are secretory granules and a prominent rough endoplasmic reticulum. Cells of the midgut tube appear not to be involved in the absorption of food. © 1994 Wiley-Liss, Inc.
We used spectrometry to study variation in the contents of minor (B, Cu, Fe, Mn and Zn) and major essential elements (Ca, K, Mg, Na and P) in the muscle tissue and digestive glands of Octopus vulgaris after 1, 2, 4 or 8 days of starvation and in fed controls. The contents of the major essential elements remained constant during 8 days of starvation. Na was the principal element found in both tissues, followed by K, P and Mg. The contents of the minor essential elements were higher in the digestive gland than in the muscle tissue, with increased contents of Fe, Mn and Zn (p < .05) during starvation, confirming the high capacity of this organ to accumulate trace minerals. In muscle tissues, B, Fe and Mn contents were lower and Cu and Zn contents higher, in starved animals than in fed animals (p < .05). Significant negative correlations between the digestive gland index and the contents of Cu, Fe and Zn suggested that the loss of weight of the digestive gland during starvation is responsible for this increase in mineral concentration. This and further information on variation in mineral content will help to optimize performance of diets formulated for the octopus.
Nautilida are present and sometimes abundant in various sedimentary environments of the Jurassic series (Sinemurian to Kimmeridgian) in Normandy, but in the majority of cases the individuals are mature or at a late stage of ontogenetic development. Comparative analysis of the palaeobiogeographic distribution of Nautilida according to their ontogenetic stages shows that early post-hatching specimens are present only in particular palaeoenvironments which are rarely visible and laterally limited in outcrop. The sedimentologic and palaeoecologic originality of the Carixian, Aalenian and Bajocian deposits bearing these peculiar specimens is related to their palaeogeographic position along the western border of the Anglo-Paris Basin, on the eastern margin of the Armorican Massif, where Jurassic deposits overlie Palaeozoic rocky reefs or shoals. The egg-laying places of the Jurassic Nautilida show palaeoenvironmental features similar to those of the recent Nautilus, having been controlled by the water temperature and the nature and morphology of the sea bottoms. A hard, anfractuous and stable substratum, low sedimentation rates and warm and well-oxygenated marine waters appear to have been required for egg-laying and for the embryonic development of these cephalopods. The discovery of early post-hatching fossil Nautilida is fundamental to a better understanding of their palaeobiogeographic distribution at local to global scales. The stenotopic nature of their egg-laying places explains the segregation between newly hatched individuals and the rest of the population and leads also to a distinction between the notions of ‘dispersal potential’ and ‘settlement potential’ for populations of Nautilida. Three palaeobiogeographic maps show that Nautilida were absent in the Jurassic Boreal realm. This exclusion could be closely dependent on the thermal requirements that govern their reproduction. By comparison, the contemporary occurrence of ammonoids in this realm appears to reflect differences in reproductive strategies.
A list of 256 references dealing with avian karyology is presented. This list is updated to April 1983 and covers 587 bird species, 385 non-passerines and 202 passerines. It includes 37 non-passerines and 29 passerines that were only studied in the period from 1902 onwards to the early 1950s using less sophisticated techniques (mostly on sectioned material of gonadal tissues). The remaining 348 non-passerines and 173 passerines were studied with more advanced techniques using colchicine-treated material of feather-pulp, embryonic tissue, bone-marrow, leucocyte or tissue culture. The species studied to date belong to 25 of the 26 avian orders and to 96 of the 160 avian families.
Prehensile-tailed platyrrhines (atelines and Cebus) and procyonids (Potos) display bony tail features that have been functionally and adaptively linked to their prehensile behaviors, particularly the need to resist relatively greater bending and torsional stresses associated with supporting their body weight during suspensory postures. We compared fiber architecture of the mm. intertransversarii caudae (ITC), the prime tail lateral flexors/rotators, in 40 individuals distributed across 8 platyrrhine and 2 procyonid genera, divided into one of two groups: prehensile or nonprehensile. We tested the hypothesis that prehensile-tailed taxa exhibit relatively greater physiologic cross-sectional areas (PCSAs) to maintain tail suspensory postures for extended periods. As an architectural trade-off of maximizing force, we also predicted prehensile-tailed taxa would exhibit relatively shorter, more pinnate fibers, and a lower mass to tetanic tension ratio (Mass/P(O)). Prehensile-tailed taxa have relatively higher PCSAs in all tail regions, indicating their capacity to generate relatively greater maximum muscle forces compared to nonprehensile-tailed taxa. Contrary to our predictions, there are no group differences in pinnation angles, fiber lengths or M/P(O) ratios. Therefore, the relatively greater prehensile PCSAs are driven largely by relative increase in muscle mass. These findings suggest that relatively greater ITC PCSAs can be functionally linked to the need for prehensile-tailed taxa to suspend and support their body weight during arboreal behaviors. Moreover, maximizing ITC force production may not come at the expense of muscle excursion/contraction velocity. One advantage of this architectural configuration is it facilitates suspension of the body while simultaneously maximizing tail contact with the substrate.
Fore- and hindlimb muscles were dissected in four species of Lipotyphla: the western European hedgehog Erinaceus europaeus (Erinaceidae, Erinaceinae); the moonrat Echinosorex gymnura (Erinaceidae, Hylomyinae or Galericinae); the tailless tenrec Tenrec ecaudatus (Tenrecidae, Tenrecinae); and the common European white-toothed shrew Crocidura russula (Soricidae, Soricinae). This work completely reviews the limb musculature of these walking mammals. Twelve myological characters were evaluated in order to disclose phylogenetic relationships. The cladogram obtained supported previous ones based on cranial and dental characters. This study shows that myological characters are valuable in phylogenetic analyses.
This article reviews the history of gyrodactylid research focussing on the unique anatomy, behaviour, ecology and evolution of the viviparous forms while identifying gaps in our knowledge and directions for future research. We provide the first summary of research on the oviparous gyrodactylids from South American catfish, and highlight the plesiomorphic characters shared by gyrodactylids and other primitive monogeneans. Of these, the most important are the crawling, unciliated larva and the spike sensilla of the cephalic lobes. These characters allow gyrodactylids to transfer between hosts at any stage of the life cycle, without a specific transmission stage. We emphasise the importance of progenesis in shaping the evolution of the viviparous genera and discuss the relative extent of progenesis in the different genera. The validity of the familial classification is discussed and we conclude that the most significant division within the family is between the oviparous and the viviparous genera. The older divisions into Isancistrinae and Polyclithrinae should be allowed to lapse. We discuss approaches to the taxonomy of gyrodactylids, and we emphasise the importance of adequate morphological and molecular data in new descriptions. Host specificity patterns in gyrodactylids are discussed extensively and we note the importance of host shifts, revealed by molecular data, in the evolution of gyrodactylids. To date, the most closely related gyrodactylids have not been found on closely related hosts, demonstrating the importance of host shifts in their evolution. The most closely related species pair is that of G. salaris and G. thymalli, and we provide an account of the patterns of evolution taking place in different mitochondrial clades of this species complex. The host specificity of these clades is reviewed, demonstrating that, although each clade has its preferred host, there is a range of specificity to different salmonids, providing opportunities for complex patterns of survival and interbreeding in Scandinavia. At the same time, we identify trends in systematics and phylogeny relevant to the G. salaris epidemics on Atlantic salmon in Norway, which can be applied more generally to parasite epidemiology and evolution. Although much of gyrodactylid research in the last 30 years has been directed towards salmonid parasites, there is great potential in using other experimental systems, such as the gyrodactylids of poeciliids and sticklebacks. We also highlight the role of glacial lakes and modified river systems during the ice ages in gyrodactylid speciation, and suggest that salmon infecting clades of G. salaris first arose from G. thymalli in such lakes, but failed to spread fully across Scandinavia before further dispersal was ended by rising sea levels. This dispersal has been continued by human activity, leading to the appearance of G. salaris as a pathogen in Norway. We review the history and current status of the epidemic, and current strategies for elimination of the parasite from Norway. Finally, we consider opportunities for further spread of the parasite within and beyond Europe.
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