Ontogenetic trajectories of septal spacing in Early Jurassic belemnites from Germany and France,and their palaeobiological implications

Based on well‐preserved belemnites, the ontogenetic trajectories of septal spacing between succeeding chambers were analysed. In the examined species (Passaloteuthis laevigata, Parapassaloteuthis zieteni and Pseudohasitites longiformis) that come from Buttenheim, Germany, and Lixhausen, France, the ontogenetic trajectories of septal spacing follow exponentially increasing trends with no decreasing phase of septal crowding during the earliest ontogenetic stage. The absence of a decreasing trend at the earliest ontogenetic stage is a unique character in contrast with those in modern cuttlefish and ancient and modern nautiloids, in which the decreasing trends are related to hatching events. These ontogenetic septal spacing trends suggest that the belemnite hatchlings had only a protoconch with no chamber. These belemnite hatchlings with no chamber and therefore small embryonic shell diameter are similar to those of ammonoids. Significant difference in a statistical test that compared the protoconch size between the two localities, might suggest that there was limited transportation at the embryonic stage, although it could also just indicate differences in regional environmental conditions, age and/or degree of time averaging which might differ between the examined taxa.     

Inflated protoconchs and internally dissolved, coiled protoconchs of nudibranch larvae: different developmental trajectories achieve the same morphological result

Abstract. Light and scanning electron microscopy were used to examine protoconch form in eight species of planktotrophic heterobranch larvae, including four nudibranch species with a coiled (type 1) protoconch, two nudibranch species with an inflated (type 2) protoconch, and two cephalaspid species with a coiled protoconch. The coiled protoconchs of the cephalaspids and nudibranchs have a similar form at hatching, and shell growth up to metamorphic competence is hyperstrophic. Shell added to coiled protoconchs during the larval stage overgrows all but the left wall of the initial protoconch that exists at hatching. The entire protoconch of cephalaspids, including overgrown areas, is retained through metamorphosis. However, during later larval development in nudibranchs with a coiled protoconch, overgrown shell is completely removed by dissolution. As a result, regardless of whether nudibranch larvae hatch with an inflated or coiled protoconch type, the protoconch is a large, hollow cup at metamorphic competence. The protoconch of nudibranchs is shed at metamorphosis and absence of a post-metamorphic shell is correlated with absence of visceral coiling in this gastropod group. Internal dissolution of the coiled protoconch in nudibranchs allows the left digestive gland to uncoil prior to metamorphic shell loss. Retention of overgrown protoconch whorls in cephalaspids allows the attachment plaque of the pedal muscle to migrate onto the parietal lip of the post-metamorphic shell. Release from this constraint in nudibranchs, in which the larval pedal muscles and the entire protoconch are lost at metamorphosis, may have permitted internal protoconch dissolution and precocious uncoiling of the visceral mass, as well as evolutionary emergence of the inflated larval shell type.     

Véligère planctotrophe du doridien Aegires punctilucens (D'Orbigny) (Mollusca: Nudibranchia: Notodorididae): Description et métamorphose

Different larval planktonic stages of the nudibranch Aegires punctilucens (D'Orbigny) are described. The youngest has a shell of the protoconch type 1 (Thompson) and a bilobed velum. After loss of the shell, the next stage is characterized by a large velum with broad and thick lobes. The mantel covers the body and has tubercles which grow progressively. Spicules appear in the mantle and in the foot; they are simple, triradiate or cross-shaped. A zone of hyaline denticles are present in the stomach lumen.Metamorphosis has been obtained under laboratory rearing. After the gradual resorption of the velum, the animal looks like a small dorid and is grey with white spots. The foot is slender and there are 14 tubercles always arranged in the same way and bristled with spicules.After discussing the species identification, the veliger is compared with other nudibranch larvae. The development of Aegires is very unusual with a two-stage metamorphosis, the first at the time of loss of the shell, and the second at loss of the velum cast. The intermediate stage between those two stages is planktonic.     

Reproduction and larval development of the gastropod <Emphasis Type="Italic">Cryptonatica janthostoma</Emphasis> (Gastropoda: Naticidae)

The larval morphology of the gastropod Cryptonatica janthostoma inhabiting the Northwest Pacific was described for the first time. Hatched planktotrophic veligers of C. janthostoma had shells 250 μm in height with 0.8 whorls, a bilobate velum with a dark brown pigmentation band shaped along its edge, pair of eye spots, tentacles and statocysts. The surface of the embryonal shell (protoconch 1) was covered with fine granules extended at the dorsal side and rounded at lateral surfaces. Concentric crests and growth lines occurred on part of the shell of late free-swimming larvae (protoconch 2) The velum of the C. janthostoma larvae remained bilobate during the pelagic stage of development, whereas it was divided in 4 lobes during larval development in most of the other species of the Naticidae family. The veliger of C. janthostoma was similar to that of Natica montagu from Danish waters [16] by its shape, pigmentation, shell sculpture and velum structure.     

Appearance of morphological novelty in a hybrid zone between two species of land snail

On the small oceanic island of Chichijima, two endemic species of land snails, Mandarina mandarina and M. chichijimana, have discrete distributions separated by a hybrid zone. This study investigates the potential of hybridization as a source of morphological novelty in these snails. Mandarina mandarina possesses a shell with a higher whorl expansion rate and a smaller protoconch than M. chichijimana, relative to shell size. The number of whorls and shell size of M. mandarina do not differ from those of M. chichijimana, because the effect of higher expansion rate on number of whorls and size of the former is compensated for by its smaller protoconch. The whorl expansion rate and protoconch diameter of the individuals from the hybrid populations are intermediate or typical of either of the two species, and their average values show clinal changes along the hybrid zone. However, the hybrid populations include exceptionally high shells with many whorls and flat shells with few whorls, which are never found in the pure populations of either species. In addition, gradual increases in variance in shell height and number of whorls were found from the edges to the center of the hybrid zone. A combination of low expansion rate (typical of M. chichijimana) and a small protoconch (typical of M. mandarina) produces a shell with an extremely large number of whorls because of the geometry of shell coiling. However, the combination of high expansion rate and a large protoconch produces a shell with an extremely small number of whorls. Because of the correlation between the number of whorls and shell height, shells with an exceptional number of whorls possess an extraordinarily high or flat spire. Hybrids can inherit a mosaic of characters that, as they play out during growth, lead to novel adult morphologies. These findings emphasize the importance of hybridization as a source of morphological variation and evolutionary novelty in land snails.     

Taxonomy and palaeobiology of the Bathonian (Middle Jurassic) tulitid ammonite Morrisiceras

Taxonomic revision of a number of species belonging to the Middle Bathonian tulitid genus Morrisiceras (Morrisiceras Buckman - macroconchs and Holzbergia Torrens - microconchs) from the Polish Jura (south-central Poland) and England, shows that the genus is in fact represented by one, albeit morphologically very plastic (especially macroconchs), species Morrisiceras morrisi (Oppel). In the Polish Jura area, all of the previously described morphotypes of the macroconch, along with its microconch Holzbergia, are characterized by their identical stratigraphic ranges, both being confined to the Middle Bathonian Morrisi Zone. Much smaller microconchs (males) may have attained maturity earlier than their macroconchs (females). Morphologically very plastic macroconchs seem to have attained full maturity at various shell diameters. Such phenomenon is known in recent coleoids and similarly may be the result of changing environmental conditions. Palaeobiogeographically, the main area occupied by the species was confined to the epicratonic seas, which spread across what is now present-day central and North-West Europe, with some occurrences in western Asia (Turkmenistan/Uzbekistan) and sporadic occurrence in a deep-water facies of Apulia (Italy). Taphonomical observations suggest that Morrisiceras shells have not undergone significant post-mortem drifting or transport after deposition. The preservation of some of the Morrisiceras morphotypes, occurring as dorso-ventrally flattened specimens in the host clays, may indicate that they were quickly buried in life position after they have landed on the sea-floor.     

First published record of urban malaria in Puerto Gaitán, Meta,Colombia

Patterns of malaria cases were compared between the department of Meta and the municipality of Puerto Gaitán, Colombia, to examine temporal change in malaria from 2005-2010. During this time frame in Meta the mean ratio was 2.53; in contrast, in Puerto Gaitán it was 1.41, meaning that a surprisingly high proportion of Plasmodium falciparum cases were reported from this municipality. A detailed analysis of data from Puerto Gaitán for 2009 and 2010 detected a significant difference (χ2, p < 0.001) in the distribution of plasmodia, with Plasmodium vivax more prevalent in 2009 and P. falciparum in 2010. Males had the highest number of cases but there was no difference in the distribution of cases between sexes and years. In both years, for both sexes, people 16-40 accounted for the majority of cases (58.9% in 2009; 60.4% in 2010). There were significant differences in the distribution of both P. vivax (χ2, p < 0.01) and P. falciparum cases (χ2, p < 0.05) by geographic setting (urban vs. non-urban) between years. Urban cases of both P. vivax and P. falciparum are recorded in this study for the first time in Puerto Gaitán, possibly the result of area wide displacement and migration due to armed conflict.     

Usefulness of the opercular nucleus for inferring early development in neritimorph gastropods

The early ontogeny of gastropods (i.e., planktotrophic vs. nonplanktotrophic) may be inferable from the morphology of the protoconch in adult shells. The protoconch consists of both embryonic and larval shells in species with planktotrophic development; the embryonic shell forms in the intracapsular period and the succeeding larval shell gradually develops during the larval period. In nonplanktotrophic species, on the other hand, there is no additional growth of the larval shell and the protoconch consists exclusively of a relatively large embryonic shell formed prior to hatching. This "shell apex theory" has been applied to many species of shell-bearing gastropods, but biotic and abiotic erosion of the apex often prevents detailed examination of the protoconch and subsequent inferences about ontogeny. I examined the gastropod operculum to test its utility for predicting developmental mode, drawing on the Neritimorpha as model taxa. Most aquatic members of Neritimorpha were found to bear an operculum with a clearly demarcated nucleus; SEM observations reveal four types of nuclei, which correspond to different types of protoconch morphologies and observed ontogenies for the study species. The nucleus is secreted before metamorphosis, fits into the shell aperture of the larva, and reflects early ontogeny as morphology, as does the protoconch. Moreover, the apparently organic (rather than calcareous) composition of the nucleus makes it nearly invulnerable to erosion and very advantageous, compared to the protoconch, in this ecologically diverse group, whose habitats range from freshwater streams and mangrove swamps to rocky shores and deep-sea hydrothermal vents. The measurements of the nucleus are also valuable for taxonomic purposes, especially in the species identification of veliger larvae and juvenile snails. On the other hand, the opercular nuclei of the Caenogastropoda and Heterobranchia are often eroded away in adult individuals; even if present, the morphology of the nuclei does not seem to clearly reflect early ontogeny in those groups.     

Internal embryonic brooding and development in the southern Australian micro-snail Tricolia rosea (Angas, 1867) (Vetigastropoda: Phasianellidae: Tricoliinae)*

ABSTRACT

Internal embryonic brooding has been suggested as an adaptation to enhance reproductive success in minute gastropods. It is rare in vetigastropods, previously known in only two species of Spectamen Iredale, 1924 (Solariellidae) from South Africa. Herein it is confirmed in the temperate Australian micro-snail Tricolia rosea (Angas, 1867), with up to 46 embryos observed within a gravid female. Embryos are brooded to an advanced stage, possessing a translucent, calcified shell and a calcified operculum. The initial protoconch is colourless, spirally sculptured and delineated by a consistent axial demarcation at the 0.75 whorl mark, when it measures 320?µm across. Beyond this, the second part of the protoconch is tinted pink, the strong spiral sculpture continues but the ribs and interstices are broader, with smoother surface microsculpture. At the 1.1 to 1.125 whorl mark the protoconch measures 400?µm across when transition to smooth teleoconch sculpture occurs. No brooded embryos possessed teleoconch sculpture. The potential relationship of protoconch morphology to embryonic development, hatching, feeding and release are considered. The mechanism of fertilisation is unknown, but embryos in a brood are at the same developmental stage. Unanswered questions in embryonic development and problems with protoconch terminologies in vetigastropods are also discussed.     

The expression of an engrailed protein during embryonic shell formation of the tusk-shell, Antalis entalis (Mollusca, Scaphopoda)

SUMMARY This study presents the first detailed account of the larval and early post-metamorphic development of a scaphopod species, Antalis entalis , since 1883. Special reference is given to the expression pattern of an engrailed protein during the formation of the embryonic (protoconch) and adult shell (teleoconch). We found that in the trochophore-like larva the engrailed protein is expressed in shell-secreting cells at the margin of the protoconch close to the mantle edge. During metamorphosis the growth of the protoconch and expression of the engrailed protein along its margin stop and the teleoconch starts to form. These data suggest a different genetic background regarding protoconch and teleoconch formation in the Scaphopoda and possibly all Conchifera, thus inferring a different evolutionary origin of both organs. The single anlage of the scaphopod protoconch contradicts earlier hypotheses of a monophyletic taxon Diasoma (Scaphopoda + Bivalvia), which has been mainly based on the assumption of a primarily bilobed shell in both taxa. Comparative data on engrailed expression patterns suggest nervous system patterning as the basic function of engrailed in the Bilateria. However, there are several independent gain-of-function events, namely segment compartmentation in the Annelida and Arthropoda, protoconch formation in the Mollusca, skeletogenesis in the Echinodermata, and limb formation in vertebrates. These findings provide further evidence that homologous genes may act in very different pathways of bilaterian body plan formation in various animal phyla.     

A Genetic Test of Sexual Size Dimorphism in Pre-Emergent Chinook Salmon

Sex differences in early development may play an important role in the expression of sexual size dimorphism at the adult stage. To test whether sexual size dimorphism is present in pre-emergent chinook salmon (Oncorhynchus tshawytscha), alevins were reared at two temperatures (10 °C and 15 °C) and sexed using the OtY1 marker on the Y-chromosome. Linear mixed models were used to test for sex differences in alevin size within families while controlling for the random effects of sire and dam nested within sire. Males and females did not differ in weight at 10 °C but males were heavier than females at 15 °C. Sex accounted for 2% of the within-family variance in weight. In addition, at 15°C, the relationship between weight and sex was greater in families with larger eggs. Whereas male-biased sexual size dimorphism was present at the juvenile stage, female-biased sexual size dimorphism was present at sexual maturity. Males were also younger than females at sexual maturity. A head start on growth by males may underlie their earlier maturation at a smaller size, thus leading to female-biased SSD at the adult stage.     

Hsp70 and lipid peroxide levels following heat stress in Xeropicta derbentina (Krynicki 1836) (Gastropoda,Pulmonata) with regard to different colour morphs

Terrestrial snails which live under dry and hot conditions need efficient mechanisms of adaptation to counteract the problems of desiccation and over-heating. A profoundly heat tolerant snail species is the Mediterranean Xeropicta derbentina, exhibiting different shell colour morphs ranging from pale white to darkly banded. Considering that dark-pigmented snails are believed to have a disadvantage due to faster heating, we investigated possible differences in the stress markers Hsp70 and lipid peroxideation between four pre-defined colour morphs which were exposed to different temperatures for eight hours. The highest Hsp70 levels were observed in response to 38-40 °C. Levels decreased when this temperature was exceeded. Snails of a pre-defined colour category 3 (with a large black band at the umbilicus side of the shell) showed the most prominent Hsp70 response. Lipid peroxideation levels also showed a maximum at 38 °C but displayed a second peak at rather high temperatures at which the Hsp70 level already had decreased (45-48 °C). Particularly pure white snails (category 1) and the most pigmented ones (category 4) were found to have different levels of lipid peroxidation at 38 °C and 45 °C compared to the other morphs. A hypothesis involving a combined two-phase defence mechanism, to which both, the Hsp70 protection system and the antioxidant defence system, may contribute, is discussed.     

Effects of Riyadh cement industry pollutions on some physiological and morphological factors of Datura innoxia Mill. plant

Cement factory emissions into air cause serious air pollution and affect the plant and animal life in the environment. Herein, we report the effects of cement industry emissions (O₃, SO₂ and NO₂) in air, as pollutants, at Riyadh City on Datura innoxia Mill. plant. Morphological characters including plant height, leaves area and number, fresh and dry weight of shoot and root systems of D. innoxia showed a significant reduction from their normal control plants as a response to exposure to pollutant emissions. Chlorophyll and carotenoid contents recorded reductions in values compared to control plant, and the lowest values of chlorophyll A, B, total chlorophyll, carotenoids and total pigments were 0.431, 0.169, 0.60, 0.343 and 0.943 mg/g respectively at a distance of 1–5 m from the cement factory in fruiting stage. These changes in values may be attributed to a probable deceleration of the biosynthetic process rather than degradation of pigments. Further D. innoxia showed a significant (P < 0.01) reduction in non-reducing and total sugars, protein and total lipid contents compared with the control plant. The root system recorded the lowest values of reducing sugars (0.350 mg/g f. wt.), non-reducing sugars (0.116 mg/g f. wt.), total sugars (0.466 mg/g f. wt.), protein content (0.931 mg/g f. wt.) and total lipids content (0.669 mg/g f. wt.) in fruiting stage at a distance of 1–5 m from the cement factory. The peroxidase activity of shoot and root systems of the studied plant was also significantly higher than those of control plant. Thus a highest value of (29.616 units/g f. wt.) peroxidase activity was recorded in vegetative stage of shoot system at a distance 1–5 m from the cement factory. Results of the study indicated that cement industry emission strongly influence the physiology and morphology of date palm D. innoxia which contribute date fruits, a staple food in the Arab world.     

Illegal harvesting and livestock grazing threaten the endangered orchid Dactylorhiza hatagirea (D. Don) Soó in Nepalese Himalaya

Harvesting of orchids for medicine and salep production is a traditional practice, and increasing market demand is spurring illegal harvest. Ethno‐ecological studies in combination with the effect of anthropogenic disturbance are lacking for orchids. We compared population density and structure, and tuber biomass of Dactylorhiza hatagirea (D. Don) Soó for three years in two sites: Manang, where harvesting of medicinal plants was locally regulated (protected), and Darchula, where harvesting was locally unregulated (unprotected). Six populations were studied along an elevation gradient by establishing 144 temporary plots (3 × 3 m²) from 3,400 to 4,600 m elevations. Mean density of D. hatagirea was significantly higher in the locally protected (1.31 ± 0.17 plants/m²) than in the unprotected (0.72 ± 0.06 plants/m²) site. The protected site showed stable population density with high reproductive fitness and tuber biomass over the three‐year period. A significant negative effect (p < .1) of relative radiation index (RRI) on the density of the adult vegetative stage and a positive effect of herb cover on juvenile and adult vegetative stages were found using mixed zero‐inflated Poisson (mixed ZIP) models. The densities of different life stages were highly sensitive to harvesting and livestock grazing. Significant interactions between site and harvesting and grazing indicated particularly strong negative effects of these disturbances on densities of juvenile and adult reproductive stages in the unprotected site. Semi‐structured interviews were conducted with informants (n = 186) in the villages and at the ecological survey sites. Our interview results showed that at the protected site people are aware of the conservation status and maintain sustainable populations, whereas the opposite was the case at the unprotected site where the populations are threatened. Sustainability of D. hatagirea populations, therefore, largely depends on controlling illegal and premature harvesting and unregulated livestock grazing, thus indicating the need for permanent monitoring of the species.     

Checklist of the helminth parasites of the genus Profundulus Hubbs, 1924 (Cyprinodontiformes,Profundulidae), an endemic family of freshwater fishes in Middle-America

From December 2012 to November 2014, 267 fish belonging to the family Profundulidae (representing nine of the 11 species of the genus Profundulus) were collected in 26 localities of Middle-America, across southern Mexico, Guatemala, and Honduras, comprising the distribution range of the genus, and analyzed for helminth parasites. Additionally, a database with all ten available published accounts of the helminth parasite fauna of this genus (the only genus within the family) was assembled. Based on both sources of information, a checklist containing all the records was compiled as a tool to address future questions in the areas of evolutionary biology, biogeography, ecology and phylogeography of this host-parasite association. The helminth parasite fauna of this fish group consists of 20 nominal species, classified in 17 genera and 14 families. It includes six species of adult digeneans, five metacercariae, two monogeneans, one adult cestode, three adult nematodes and three larval nematodes. The profundulid fishes are parasitized by a specialized group of helminth species (e.g. Paracreptotrema blancoi sensu Salgado-Maldonado et al. (2011b), Paracreptotrema profundulusi Salgado-Maldonado, Caspeta-Mandujano & Martínez Ramírez, 2011, Phyllodistomum spinopapillatum Pérez-Ponce de León, Pinacho-Pinacho, Mendoza-Garfias & García-Varela, 2015, Spinitectus humbertoi Mandujano-Caspeta & Moravec, 2000, Spinitectus mariaisabelae Caspeta-Mandujano Cabañas-Carranza & Salgado-Maldonado, 2007 and Rhabdochona salgadoi Mandujano-Caspeta & Moravec, 2000), representing the core helminth fauna that are not shared with other Middle-American fish species.     

OBSERVATIONS ON THE CHROMATINIC BODIES OF Streptomyces coelicolor

Colonies of Streptomyces coelicolor growing on cellophane and impression preparations from sporing colonies were stained for chromatin by the methods of Feulgen, DeLamater (1951), and Piéchaud (1954). The chromatinic bodies of the substrate hyphae have a great variety of configurations. During the development of the spores, elongated chromatinic structures in the young aerial hyphae separate into a number of subunits and a single round chromatinic body is included in each spore.     

Ontogenetic Torsion and Protoconch Form in the Archaeogastropod Haliotis kamtschatkana: Evolutionary Implications

Ontogenetic torsion in archaeogastropods has strongly influenced theories about early gastropod evolution, but the seminal studies by Crofts (1937, 1955) remain the major source of information about tissue movements during this developmental process. Computer-generated reconstructions of histological sections indicate that the cephalopodium of Haliotis kamtschatkana Jonas, 1845 rotates by a full 180° relative to the shell and visceral lobe during the first quarter of pre-metamorphic development. However, a portion of pallial epithelium, including some of the shell field, accompanies the rotating cephalopodium; a process facilitated by detachment of the pallium from the apertural rim of the protoconch. Transmission electron microscopy indicates that a tract of the larval retractor muscle, which Crofts (1955) implicated in the mechanism of torsion, inserts on both pedal and pallial cells. A deep invagination of shell field epithelium is a major focus of rotational torque. As a result of pallial deformation during cephalopodial rotation, the anus and gill rudiment are restricted to the right half of the larval body for 2 days after cephalopodial rotation by 180° has been completed. Scanning and transmission electron microscopy indicate that grooves in the lateral flanks of the protoconch correspond to the deep invagination of shell field epithelium. The grooves are not created by a coiling type of accrelionary shell growth or by flexion of the protoconch. A calcareous shelf is secondarily added to the periostracal template of the protoconch along its visceral apertural rim. Morphogenetic movements during ontogenetic torsion in this species are more complex than a simple rotation between cephalopodium and visceropallium and the protoconch shows no evidence of exogastric coiling. © 1997 Published by Elsevier Science Ltd on behalf of The Royal Swedish Academy of Sciences.     

THE PLANKTONIC VELIGER OF AMPHIBOLA CRENATA (GMELIN)

Amphibola crenata (Gmelin) has a well-developed planktonic veligerstage which remains in the plankton for several weeks and feedsactively. It resembles an opisthobranch veliger with a sinistralshell and conspicuous black larval kidney. After metamorphosisthe pitch of the coil of the shell is altered so that the bodywhorl grows, over the larval whorls and produces a dextrallycoiled adult shell with an internal protoconch. (Received 1 July 1980;