Phylogeny and origins of Enchytraeidae

Phylogenetic analyses of Achaetinae (Enchytraeidae: Oligochaeta) and other bisetate enchytraeids indicate that the achaetines include the earliest species of Enchytraeidae but that Achaetinae is not monophyletic. The earliest species of bisetate enchytraeid now extant are restricted to South America, Africa, and India. As this part of the enchytraeid lineage is ancestral to other enchytraeid taxa, it is suggested that Enchytraeidae may have arisen in South America or a contiguous Southern land mass.Less than 50% of the 11 genera of Enchytraeidae considered are supported by the results of these analyses as evolutionary or phylogenetic groups. Five are substantiated as monophyletic: Achaeta, Lumbricillus, Fridericia, Randidrilus, and Enchytronia. In addition to most of the achaetine genera, Marionina is shown to be in great need of revision. Its recognition is a continuing source of confusion to taxonomic resolution of Enchytraeidae.     

Terrestrial Enchytraeidae (Oligochaeta) and Parergodrilidae (Polychaeta) from Sweden, with description of a new enchytraeid species

Forty-four cnchytraeid species and one parergodrilid species are reportcd from terrestrial habitats in Sweden. Eighteen of the Enchytraeidae are ncw records, including Achueta bifollicula sp.n. Thc new species has 4046 segments; dorsal sctal follicles; follicle-like bodics vcntrally at IV and V; clitellum dorsally interrupted, with fields of hyaline cells; three pairs of primary septa1 glands, and one pair of secondary ones behind 5/6; dorsal blood vessel originating in VII; anteclitellar nephridia in three pairs at 6/7-8/9; long, large spermathecae reaching to X-XII; sperm funnels with a 1ength:width ratio G7:l; seminal vesicles extending through three scgments. The usefulness of the clitellar structure of A chaeta species as a taxonomic critcrion is discussed.     

Fridericia larix sp. nov. (Enchytraeidae, Oligochaeta) from Irish soils

A new species of Fridericia (Enchytraeidae, Oligochaeta) is described from soils in Ireland. It was found during sampling campaigns in the framework of a comprehensive taxonomic revision of the genus (Schmelz, 2003. Taxonomy of Fridericia (Oligochaeta, Enchytraeidae). Revision of species with morphological and biochemical methods. Abh. Naturw. Ver. Hamburg, N.F. 38, 1–415, figs. 1–73), but it was not included in that study. Fridericia larix sp. nov., named in reference to the type locality, belongs to the large and taxonomically difficult group of species with two diverticula per spermatheca. It is distinguished from all known congeners by the following combination of characters: (1) a maximum of four chaetae in ventral preclitellar bundles; (2) oesophageal appendages poorly branched; (3) no pharyngeal glands in segment VII; (4) coelomocytes without refractile vesicles; (5) clitellum girdle-shaped, cell distribution alike on all sides; (6) bursal slit of male copulatory organ mainly transverse; (7) no subneural glands; (8) spermathecal diverticula not stalked. Further distinguishing characters are: (9) an asymmetrical arrangement of chaetae in the first lateral postclitellar bundles, with one large chaeta and one small chaeta per bundle (Fig. 1b, “lc XVI”); (10) the length ratio of spermatozoa to spermatozoal nuclei (6:1–7:1); and (11) a wavy inner surface in parts of the epithelium of the spermathecal ampulla (Fig. 1i, arrow).See also Electronic Supplement at: http://www.senckenberg.de/odes/05-05.htm     

Marine Oligochaeta from the Koster Area, West Coast of Sweden, with Descriptions of Two New Enchytraeid Species

A total of 28 species of marine Oligochaeta (belonging to the families Naididae, Tubificidae and Enchytraeidae) are reported from eulittoral and sublittoral sediment samples taken in the Koster area on the Swedish West Coast. Lumbricillus algensis sp.n. and Grania ovitheca sp.n. are described and their morphological and taxonomical relations to other enchytraeids are discussed. L. algensis is characterized mainly by its spermathecae, which project into segment VI, and by its very large penial bulbs. G. ovitheca possesses no dorsal setae, the ventral setae being present posterior to the clitellum only, and its spermathecae consist of a narrow duct and a large egg-shaped to oval ampulla, filling most of the coelom of segment V. Four sublittoral species, Limnodriloides barnardi (Tubificidae), Lumbricillus semifuscus, Marionina sublitoralis and Grania roscoffensis (all Enchytraeidae) are reported as new to the Swedish fauna.     

Two new species of freshwater Oligochaeta from the North-west Iberian Peninsula: Krenedrilus realis sp. nov. (Tubificidae) and Cernosvitoviella bulboducta sp. nov. (Enchytraeidae)

Two new species of aquatic Oligochaeta are described from the North-west Iberian Peninsula: Krenedrilus realis sp. nov. (Tubificidae) and Cernosvitoviella bulboducta sp. nov. (Enchytraeidae). Krenedrilus realis is the fourth species in a genus of small and presumably plesiomorphic Tubificinae. It is closely related to K. sergei Giani, Erséus & Martínez-Ansemil, 1990. Cernosvitoviella bulboducta belongs to a genus of small amphibiotic enchytraeids. It is close to C. ampullax Klungland & Abrahamsen, 1981 and C. tatrensis (Kowalewski, 1916). Supplementary data to the diagnosis of C. tatrensis are given. The presence of two small glands attached to the gut immediately behind the pharyngeal bulb is noticed in C. bulboducta and C. tatrensis . This previously unknown character is probably more common in the genus than has been supposed.     

Demonstration of β-glucan receptors in the skin of aquatic mammals—a preliminary report

Using immunohistochemistry, the study clearly demonstrates three important β-glucan receptors (Ficolin/P35, MBL, Dectin-1; members of the lectin-complement pathway of innate immunity) in the integument of six marine and freshwater aquatic mammals (Northern fur seal, Common seal, Walrus, Coypu, Capybara, Otter), but only weakly in two dolphin species. Most of the non-dolphin mammals exhibited strong reactions, especially with regard to the skin glands (tubular apocrine glands, sebaceous glands), for L-Ficolin/P35 and MBL. Distinct reaction staining could also be observed in the epidermis and the outer epithelial sheath of primary hair follicles. Positive Dectin-1 staining was limited to secretory cells of the apocrine tubular glands, and to peripheral and central cells of sebaceous glands of the seals. The Capybara was the only animal to show a clear Dectin reaction in the epidermis (stratum granulosum). The findings are discussed with regard to the constant and high microbial challenge of the skin in the aquatic medium, and variations in hair density of the animals.     

石磺科3种贝类皮肤显微结构比较

应用石蜡切片和H.E染色技术,对石磺科(Onchidiidae)3个属的代表物种:瘤背石磺(Onchidium struma)、平疣桑椹石磺(Platevindex mortoni)和里氏拟石磺(Paraoncidium reevesii)的皮肤进行了组织学观察及参数测量比较。结果表明,3种石磺的皮肤虽然厚度不一,但基本结构相似,均由角质膜、表皮和真皮构成。角质膜是一层覆盖于表皮角质层上的蛋白质薄膜;表皮由多层上皮细胞构成,包括角质层、颗粒层和生发层;真皮包括疏松层和致密层,疏松层中嵌有颗粒腺和黏液腺两种腺体。3种石磺的皮肤厚度、各组织相对厚度及腺体数量等均存在差异。将结构差异与石磺的栖息环境进行比较分析后得到:陆栖为主的瘤背石磺皮肤表皮角质化程度高,颗粒腺发达;以水栖为主的里氏拟石磺表皮角质化程度相对低,黏液腺发达;而水陆两栖的平疣桑椹石磺,皮肤角质化程度介于前述二者之间,颗粒腺与黏液腺均不发达。研究结果体现了三者不同的生态适应特征,也为深入探讨海洋无脊椎动物从海洋向陆地进化的研究提供形态学依据。     

Ultrastructure of the body wall of three species of Grania (Annelida: Clitellata: Enchytraeidae)

De Wit P., Erséus C. and Gustavsson L.M. 2011. Ultrastructure of the body wall of three species of Grania (Annelida: Clitellata: Enchytraeidae). —Acta Zoologica (Stockholm) 92 : 1–11. The body wall of three species of Grania, including the cuticle, epidermis and the musculature, are studied using TEM. The cuticle is similar to previously studied enchytraeids, with an orthogonal grid pattern of collagen fibers. This pattern is also seen in Crassiclitellata, which has been suggested as the sister taxon of Enchytraeidae. Variation of epicuticular and fiber zone patterns seen in Naididae (formerly Tubificidae and Naididae) seem to be lacking in Enchytraeidae. The fiber thickness, however, varies between Grania species and may be a phylogenetically informative character. The epidermis consists of supporting cells, secretory cells and sensory cells. Basal cells, typical for Crassiclitellata, were not observed. The clitellum of Grania seems to consist of two types of gland cells, which develop from regular epidermal tissue. It is possible that more cell types exist in different regions of the clitellum, however. The body wall musculature is arranged somewhat differently from that of closely related taxa; this refers to the reduction of circular and outer, triangular longitudinal muscle fibers, while the inner, ribbon‐shaped longitudinal muscle fibers are well‐developed. A search was conducted for the cause of the peculiar green coloration of Grania galbina De Wit and Erséus 2007, and it was concluded that neither cyanobacteria nor epidermal pigment granules were present in the fixed material.     

Phylogenetics of some Enchytraeidae (Annelida: Oligochaeta): A preliminary investigation of relationships to the Haplotaxidae

In phylogenetic considerations of the Oligochaeta and the family Enchytraeidae, Propappus has been considered the ancestral or even the archetypal enchytraeid genus. Three nominal species are presently included in Propappus Michaelsen, 1905, P. volki Michaelsen, 1916, P. arhyncotus Sokolskaja, 1972, and the type species of the genus, P. glandulosus Michaelsen, 1905. Examination of type material of P. glandulosus and P. volki, as well as other material of the latter, showed that these species have a single pair of testes in segment XI and a single pair of ovaries in segment XIII. According to current classifications of the Oligochaeta, these species of Propappus cannot be retained in the Enchytraeidae. A phylogenetic analysis including two species of Propappus and 29 species of Haplotaxidae suggest a sister group relationship between Propappus and some Enchytraeidae and Haplotaxidae.     

Marine Oligochaeta of Jiaozhou Bay,Yellow Sea coast of China

Sixteen species of marine Oligochaeta (8 Tubificidae, 1 Naididae, 6 Enchytraeidae, 1 Megascolecidae) are recorded from the Qingdao area, at about 36° N on the Chinese Yellow Sea coast. Taxonomic remarks are given for most species, of which none appears new to science.Limnodriloides victoriensis Brinkhurst & Baker andEnchytraeus kincaidi Eisen, previously known from the Northeast Pacific, are described from Asia for the first time. These, as well asMonopylephorus rubroniveus Levinsen and aLumbricillus sp., are interpreted as members of a temperate fauna, while all the remaining species have previously been reported from Hong Kong (at about 22° N) and thus are regarded as subtropical/tropical forms in the Yellow Sea.     

Fine structure of reproductive glands in two primitive marine pulmonates (Basommatophora: Siphonariidae)

Within the clade Euthyneura the marine basommatophorans are particularly neglected. More morphological and molecular studies are needed because their phylogenetic relationships with other pulmonates remain unresolved. The present study examines the most conspicuous reproductive gland, the glandular complex in two marine limpets, Siphonaria capensis and S. serrata (Pulmonata: Basommatophora) at both gross and fine structural levels. These two sympatric species with different developmental modes were selected to compare the structure and function of this enormous glandular structure. In both S. capensis and S. serrata, the glandular complex shows an undifferentiated state composed of an acidophilic albumen gland and a basophilic mucous gland. The glands contain secretory cells and supporting cells (= ciliated cells) that are highly ciliated. When the histochemical properties of the glandular complex were compared with those of siphonariid egg masses (of each species) it could be established that the albumen gland was responsible for the production of perivitelline fluid whereas the mucous gland secreted substances that help in the assembly of mucous layers surrounding the egg capsules. We suggest that the presence of a single glandular complex comprised of two glands is the most primitive organization of reproductive glands in pulmonates. Furthermore, the histology, fine structure and histochemistry of these glands are very similar to those of the reproductive glands of opisthobranchs.     

Marine lifestyle is associated with higher baseline corticosterone levels in birds

Because seawater is hyperosmotic relative to body fluids of most vertebrates, marine lifestyle is expected to strongly influence the physiology of marine tetrapods. Regulating the salt content of body fluids is energetically costly; and osmoregulatory organs may not totally overcome salt load and/or water loss. As a consequence, marine lifestyle should influence physiological systems involved in the maintenance of the physiological balance (homeostasis), in the mobilisation of energetic resources (e.g., to fuel salt excretion), or in the acquisition of resources (e.g., fresh water). Corticosterone (CORT) is one such ‘generalist’ mediator that is linked with energy expenditure, physiological stress and that activates osmoregulation. As a consequence, CORT is expected to be overall higher in marine tetrapods but this hypothesis has never been tested. Using comparative analyses, we tested this hypothesis in birds, a lineage for which available data on baseline CORT allow comparing marine versus terrestrial species, and species with or without salt glands. We found that marine species (and species with salt glands) display significantly higher baseline CORT during the wintering (but not the breeding) stage. Although salt glands’ presence was tightly linked to phylogeny, our results suggest that marine lifestyle may impose a strong, but overlooked, influence on the allostasis‐related physiology of marine birds. Such habitat‐related variation in physiology is a major phenomenon to explore owing to its general implications for understanding the physiological basis of evolutionary transitions in habitat use. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 154–161.     

The structure of the cutaneous pedal glands in the banded snail Cepaea hortensis (Müller, 1774)

Although gastropods have been crawling through the ocean and on the land for 60 million years, we still know very little about the sticky mucus produced in their foot. Most research has been focused on marine species in particular and, to a lesser extent, on the well‐known terrestrial species Arion vulgaris and Cornu aspersum. Within this study, we aim to characterize the foot anatomy of a smaller representative of the family Helicidae, the banded snail Cepaea hortensis. We are particularly interested in the microanatomy of the foot glands, their position, and the histochemical nature of their secretory content. Characterization of the dorsal foot region of Cepaea hortensis reveals four glands, differing in their size and in the granules produced. Histochemically, three of them react positively for sugars (PAS staining and lectin affinity tests for mannose, glucose and N‐acetyl‐d ‐glucosamine) and acidic proteins (positive Alcian blue and Toluidine blue staining), indicating the presence of acidic glycosaminoglycans. The fourth gland type does not react to any of these dyes. The ventral pedal region includes two different gland types, which are positive for the presence of acidic glycoproteins, with a lectin affinity for mannose only. A comparison with Helix pomatia indicates differences regarding the number of glands and their contents. In Helix, only three gland types are described in the dorsal region of the foot, which show a similar granular appearance but nevertheless differ in their chemical composition. Congruently, there are two gland types in the ventral region in both species, whereas in Helix an additional sugar moiety is found. This raises the question whether these differences between the pedal glandular systems of both helicid species are the result of protection or size‐related adaptations, as they occur in the same habitat.     

Immunolocalization of Na/K–ATPase and Na/K/2Cl cotransporter in the tubular epithelia of sea snake salt glands

The sublingual salt gland is the primary site of salt excretion in sea snakes; however, little is known about the mechanisms mediating ion excretion. Na⁺/K⁺–ATPase (NKA) and Na⁺/K⁺/2Cl⁻ cotransporter (NKCC) are two proteins known to regulate membrane potential and drive salt secretion in most vertebrate secretory cells. We hypothesized that NKA and NKCC would localize to the basolateral membranes of the principal cells comprising the tubular epithelia of sea snake salt glands. Although there is evidence of NKA activity in salt glands from several species of sea snake, the localization of NKA and NKCC and other potential ion transporters remains unstudied. Using histology and immunohistochemistry, we localized NKA and NKCC in salt glands from three species of laticaudine sea snake: Laticauda semifasciata, L. laticaudata, and L. colubrina. Antibody specificity was confirmed using Western blots. The compound tubular glands of all three species were found to be composed of serous secretory epithelia, and NKA and NKCC were abundant in the basolateral membranes. These results are consistent with the morphology of secretory epithelia found in the rectal salt glands of marine elasmobranchs, the nasal glands of marine birds and the gills of teleost fishes, suggesting a similar function in regulating ion secretion.     

The photosensitive retinal pigments of fishes from relatively turbid coastal waters

Digitonin extracts have been prepared from the retinae of a dozen species of marine and euryhaline teleost fishes from turbid water habitats. Spectrophotometric analysis of the extracts shows that the photosensitive retinal pigments of these species have maximum absorption above 500 mµ. In nine species there are retinene₁ pigments with λ_max between 504 and 512 mµ. In the marine but euryhaline mullet, Mugil cephalus, there is a porphyropsin with λ_max 520 mµ. A mixture of rhodopsin and porphyropsin in an extract of a marine puffer, Sphoeroides annulatus, was disclosed by partial bleaching with colored light. In addition, one other species has a 508 mµ pigment, of which the nature of the chromophore was not determined. The habitats in which these fishes live are relatively turbid, with the water greenish or yellowish in color. The spectral transmission of such waters is probably maximal between 520 and 570 mµ. It is suggested that the fishes have become adapted to these conditions by small but significant shifts in spectral absorption of their retinal pigments. These pigments are decidedly more effective than rhodopsin in absorption of wavelengths above 500 mµ. This offers a possible interpretation of the confusing array of retinal pigments described from marine and euryhaline fishes.     

The ultrastructure and histology of the perinotal epidermis and defensive glands of two species of Onchidella (Gastropoda: Pulmonata)

Histology and electron microscopy were used to describe and compare the structure of the perinotal epidermis and defensive glands of two species of shell-less marine Systellommatophora, Onchidella capensis and Onchidella hildae (Onchidiidae). The notum of both species is composed of a layer of epithelial and goblet cells covered by a multi-layered cuticle. Large perinotal multi-cellular glands, that produce thick white sticky mucus when irritated, are located within the sub-epidermal tissue. The glands are composed of several types of large secretory cell filled with products that stain for acidic, sulphated and neutral mucins, and some irregularly shaped support cells that surround a central lumen. The products of the secretory cells are produced by organelles that are basal in position. The entire gland is surrounded by a well-developed capsule of smooth muscle and collagen, and in addition smooth muscle surrounds the cells within the glands. Based on the size of the gland cells, their staining properties, and the appearance of their stored secretions at the transmission electron microscope level, five different types of secretory cells were identified in O. capensis and four in O. hildae. The products of these cells, which are released by holocrine secretion, presumably mix in the lumen of the duct as they are forced out by contraction of the smooth muscle. The structural similarity of these glands to those of siphonariids, suggest that they have a common ancestry.     

Bimorphism in Male Verreaux’s Sifaka in the Kirindy Forest of Madagascar

Male primates in species with pronounced secondary sexual adornments can exhibit reversible or irreversible bimorphism, i.e., striking variation in the degree to which males express the adornments. Verreaux’s sifaka (Propithecus verreauxi verreauxi) use scent marking as a form of communication and exhibit sex differences in scent glands. Some males exhibit a pronounced brown staining around their sternal gland, whereas others do not. We studied morphological and behavioral characteristics of males in 6 social groups in Kirindy Forest, Madagascar, from November 2000 to March 2002 to evaluate the hypotheses that the bimorphism in male sifaka chest status represents alternative mating tactics and is a badge of status. Males are clearly divided into 2 categories: clean and stained chests, with rare, but informative, intermediate males. The chest staining probably results from the males scent marking with their sternal glands, because stained-chested males scent marked significantly more often than clean-chested males. Though sample sizes are small, chest status did not appear to depend on body size. Chest status is reversible and related to dominance rank. In each group, only 1 male, the dominant, was stained-chested, whereas all other (subordinate) males were clean-chested. These findings suggest that stained chests are visual and olfactory signals of dominance rank and that clean chests signal lack of competitive intent. Thus, this bimorphism may reflect alternative mating tactics used by males to maximize their reproductive success based upon their social environment.