The opercular brood chambers of Spirorbidae

Brood chambers of Januinae are cuticular and have to be shed to liberate the larvae, whereas those of Pileolaria are bounded by two epithelia and are used repeatedly. Links for interpreting these differences are to be found amongst some of the smaller genera of Pileolariinae. In Amplicaria and Vinearia the embryos are held between a pair of opercular plates, which form distal and proximal cups with the concavities facing each other. They are successive units in a series of sheddings and renewals, found generally in Spirorbidae even on non-brooding opercula. A Janua brood chamber corresponds with the distal component of such a pair, the proximal component being represented by the basal plate. In most Pileolariinae the brood chamber is formed entirely by the proximal component. Amongst Nidificaria species, some hold the embryos in a simple cup with no distal protection, but others have the aboral side of the cup extended and growing over distally, like the dorsal lip of a blastopore. The aperture that remains may be almost closed but can open again to liberate the larvae. Brood chambers of Pileolaria are exactly like that, except that they lack any calcification proximally. Those of Jugaria and Bushiella are similar, but with additional protection through retention of distal plates. Protoleodora species are subarctic and very close to Jugaria and Bushiella in distribution and morphology, but they have less calcification, readily lose their distal plates, and develop soft-walled brood pouch extensions which can accommodate very large broods. There seem to be tenuous links between the Pileolariinae and the Romanchellinae, southern hemisphere spirorbids which incubate in their tubes. Fertilization and spawning need further study.     

Seed germination in Gactaceae

The mode of germination of representatives of 89 genera of the Cactaceae, 4 genera of Portulacaceae and 1 genus of Phytolaccaceae was studied. Most of the species of the Cactaceae germinate by means of a seed lid (operculum). In the Cactaceae studied 11 kinds of germination could be distinguished, 3 of which were with, and 8 without, operculum formation.
Opercula are restricted in their occurrence to the subfamilies Cactoideae (Cereoideae) and Pereskioideae and are not found in the subfamily Opuntioideae. Within the subfamily Cactoideae operculum formation was found to occur in all tribes and in all investigated subtribes. Opercula were also found in two genera of the related family of the Portulacaceae. In the Phytolaccaceae no operculum formation was observed.     

The morphology of the sphaeromatid brood pouch (Crustacea: Isopoda: Sphaeromatidae)

The structure of the brood pouch and mouthparts of ovigerous female sphaeromatids is described. Taxonomically, these are shown to be important generic characters and some attempt is made to relate structure to function. Expanded maxillipeds (which produce a current of water through the marsupium) are shown to occur only in genera which have oostegites overlapping in the mid-line and reaching the mouthparts anteriorly. The reduction of the mouthparts of some genera cannot be explained, but it may conserve energy at the final moult. No platybranchiate genera (subfamily Cassidininae) have the mouthparts reduced but some have the maxilliped expanded. Some correlation between brood pouch structure and habitat is suggested. Genera with a brood pouch composed only of oostegites (and hence liable to disruption by turbulence and particle abrasion) occur sublittorally or, if intertidal, adopt a protected, crevice dwelling habit. Genera with a brood pouch composed of large opposing pockets (which are more able to resist disruption) occur intertidally or in shallow water, and may be found in wave-washed sand. Some wood-boring species of the genus Sphaeroma Latreille show a reduced number of oostegites when compared with non-boring species. This presumably relates to their burrowing habit.     

竹节虫化石在中国的首次发现及其生物学特征 (竹节虫目:神科,新科)(英文)

本文建立竹节虫目昆虫化石1新科,即Haginhasmatidae,包括3新属,3新种和一个本命名种：Hagiphasmaparadoxagen．etsp．nov,Aethephasmamegistagen．etsp．nov．和Orephasmaeummphagen．etsp.nov,并给出新科内属的检索表。对消化道痕迹和保存完好的亚生殖板进行了分析,并与现代类群作了比较。竹节虫化石在我国是首次报道,所有化石材料均采自河北省和辽宁省晚珠罗世义县组地层中,保存在中国地质博物馆。     

The opercular moult in Spirorbis spirorbis (L.) and S. pusilloides Bush (Polychaeta: Serpulidae)

Opercular moult has been examined in two spirorbids, the tube-incubating Spirorbis spirorbis (L.) and the opercular incubating Spirorbis pusilloides Bush. In both species epithelial ingrowth cuts off the old operculum and a new one differentiates on the proximal side of the constriction. The immediate fate of the severed tissues differs in the two species; in S. spirorbis the epithelia slowly wither as the platelike operculum finally breaks away by rupture of the cuticle while in S. pusilloides there is a cataclysmic autolysis of the epithelial tissues although the cuticle is retained and functions as an incubation chamber which ruptures at the close of incubation to release the larvae and is then shortly discarded.Opercular moult, rare in the immature animal in either species, normally begins with the onset of breeding. In S. pusilloides it is an essential preliminary to brooding and throughout the breeding season opercular moult rigidly alternates with brood incubation to produce a new incubation chamber for each successive brood. In S. spirorbis there is also some evidence of a partial correlation between brooding and opercular moult but the two events overlap and moulting is less frequent than the production of broods. A brief consideration is given to the evolution of the brooding habit and the tentative conclusion reached that opercular incubation has evolved twice in the Spirorbinae.     

Slapylitidae: a new family of hyolithids (Cambrian–?Devonian; Baltica,Laurentia, Gondwana)

Hyoliths are usually preserved as isolated skeletal elements consisting of conch, operculum, and helens. The occurrence of a conch associated with an operculum is ordinarily exceptional, and the co-occurrence of helens with other skeletal parts is a great rarity. The extraordinary finds of hyolithid conchs associated with opercula in situ are relatively abundant in the Cambrian and Ordovician clastic sediments of the Barrandian area in the Czech Republic. The platyclaviculate operculum with clavicles divided by longitudinal walls into channels characterizes members of the newly established family Slapylitidae fam. nov., which includes two genera: Slapylites Marek, 1980 known from the mid-Cambrian of West Gondwana and Baltica and Nevadalites Marek, 1976 documented from the Late Cambrian of Laurentia. To this family most probably belongs also an operculum from the Cambrian Series 2–Series 3 boundary of North Greenland and poorly known material from the Middle Devonian of Bolivia.     

Differentiation of Paenibacillus larvae subsp. larvae,the cause of American foulbrood of honeybees,by using PCR and restriction fragment analysis of genes encoding 16S rRNA

A rapid procedure for the identification of Paenibacillus larvae subsp. larvae, the causal agent of American foulbrood (AFB) disease of honeybees (Apis mellifera L.), based on PCR and restriction fragment analysis of the 16S rRNA genes (rDNA) is described. Eighty-six bacterial strains belonging to 39 species of the genera Paenibacillus, Bacillus, Brevibacillus, and Virgibacillus were characterized. Amplified rDNA was digested with seven restriction endonucleases. The combined data from restriction analysis enabled us to distinguish 35 profiles. Cluster analysis revealed that P. larvae subsp. larvae and Paenibacillus larvae subsp. pulvifaciens formed a group with about 90% similarity; however, the P. larvae subsp. larvae restriction fragment length polymorphism pattern produced by endonuclease HaeIII was found to be unique and distinguishable among other closely related bacteria. This pattern was associated with DNA extracted directly from honeybee brood samples showing positive AFB clinical signs that yielded the restriction profile characteristic of P. larvae subsp. larvae, while no amplification product was obtained from healthy larvae. The method described here is particularly useful because of the short time required to carry it out and because it allows the differentiation of P. larvae subsp. larvae-infected larvae from all other species found in apiarian sources.     

Comparative morphology of the amphibian opercularis system: I. General design features and functional interpretation

The morphology of the opercularis system of anuran and caudate amphibians suggests that it acts to produce motion of the operculum that in turn produces fluid motion within the inner ear. The operculum and opercularis muscle form a lever system, with a narrow connection between the operculum and otic capsule acting as a fulcrum about which the operculum moves in response to forces applied via the muscle. The opercula of many species possess a muscular process on which the muscle inserts, thereby increasing the moment arm through which the muscle acts. The tonicity of the opercularis muscle allows tensile forces produced by substrate vibration or other mechanical energy applied to the forelimb to be effectively transmitted to the operculum; the elasticity of the connective tissue holding the operculum in place should act to return the operculum to its original position. The opercularis systems of frogs and non-plethodontid salamanders are similar structurally and functionally; that of plethodontid salamanders is structurally distinct but also functions as a lever system. Fluid motion produced by opercular motion could stimulate various end organs of the inner ear; the saccule, lagena, and amphibian papilla are in close approximation and wave energy could directly affect their otoconial or tectorial structures. In those anurans with a tympanic ear, the stapedial footplate and operculum articulate, but this articulation allows both to move independently. The stapes-tympanum complex and opercularis system therefore appear to be independent functional systems, and it is unlikely that the opercularis system modulates middle ear responsiveness. The general design of the opercularis system is consistent with a function in reception of substrate vibrations.     

An Ultrastructural Study of Spermatozoa of the Majidae with Particular Reference to the Aberrant Spermatozoon of Macropodia longirostris (Crustacea,Decapoda, Brachyura)

A total of 17 species, in 14 genera of majids have been examined for sperm ultrastructure. The present account describes the sperm of six of these species, in two subfamilies: Pisinae—Sphenocarcinus orbiculatus and Sphenocarcinus stuckiae and Inachinae—Cyrtomaia furici, Grypacheus hyalinus, Platymaia rebierei and Macropodia longirostris. M. longirostris has the only eubrachyuran sperm in which the acrosome is known to depart radically from a subspheroidal form. The acrosome is semilunar in shape and is bordered by a very thin layer of cytoplasm and an unusually uniform, narrow band of chromatin. The apical surface of the acrosome is almost flat, though slightly concave, whereas the posterior surface forms a hemisphere, and is almost completely occupied by the thin, centrally perforate, electron dense operculum. The bulk of the acrosome consists of a homogeneous, moderately electron dense outer acrosome zone. This surrounds a small inner acrosome zone internal to which is an ellipsoidal, pale perforatorium capped by a central acrosome zone. Majid sperm are distinguished by a flattened and/or centrally depressed operculum; a further characteristic is that the pointed perforatorium is relatively short and frequently does not reach the operculum. They vary inter alia with regard to presence or absence of a posterior median process and, apparently, of centrioles and of microtubules in the nuclear arms, and in the number of these arms. Perforation of the operculum, seen in the Pisinae, is not constant in the Inachinae. Spermatozoal ultrastructure offers no certain support for a close relationship of majids with parthenopids or hymenosomatids.     

Structure and Macromolecular Composition of the Seed Coat of the Musaceae

Mature seed coats of representatives of all three genera ofMusaceae were analysed for macromolecular composition with variousmass spectrometric techniques and compared with scanning electronmicroscopy and light microscopy in combination with histochemicaltechniques. Mass spectrometric techniques are more sensitiveand more specific in identifying macromolecular compounds thanhistochemical methods. The macromolecular ‘fingerprint’of the seed coats of Musaceae showed unique components of aromaticphenols. The seed coat structure of all three genera is homogeneouswithin the Musaceae. It is characteristic at the family leveland most complex within the Zingiberales. Very remarkable arethe separation of the outer cell walls from the exotestal layer,exposing a secondary surface with silica crystals, and the relativelythick mesotesta which protects the seed, e.g. against the bitingforces and passage through the digestive tracts of dispersingagents. Germination takes place with an operculum and is facilitatedby a predetermined rupture layer in the micropylar collar. Themusaceaous seed presents a good example of the solution of conflictingdemands of protection and germination. Musaceae; Musa; Ensete; Musella; seed coat; pyrolysis (gas chromatography) mass spectrometry; histochemistry; anatomy; macromolecules; silica; lignin; cellulose; vegetable polyphenols; operculum; germination     

Ovoviviparity in the genus Excirolana (Crustacea: Isopoda)

Studies on the intertidal sand-beach isopod, Excirolana chiltoni , have shown the species to be ovoviviparous. Large yolk-filled eggs are deposited into paired uteri of the female where they remain throughout gestation. Intrauterine development progresses through five stages and terminates upon birth of the manca which is morphologically similar to the adult but lacks the eighth pair of thoracic legs. The oostegites while present are much reduced and form a genital operculum rather than a brood pouch as they do in the majority of free living isopods. Six other species of Excirolana examined in the course of this investigation show evidence of internal incubation. Ovoviviparity thus appears to be characteristic of the entire genus, members of which live on exposed sand beaches throughout tropical and warm temperate regions of the world. Internal retention of embryonic stages provides protection against a number of environmental stresses peculiar to this sort of habitat.     

Indopottia zanderi (Bryophyta,Pottiaceae) gen. et sp. nov. from the Western Ghats of India

Abstract

Indopottia zanderi, a new genus and species of the Pottiaceae, is described from the Silent Valley National Park in the Western Ghats in Peninsular India. The distinctive features of Indopottia are the leaf cells being weakly convex on both surfaces, costal stereid-band semicircular in cross-section, guide cells rounded-ovate or semicircular, seta short and operculum very long. The affinities of the allied genera, Ganguleea, Tortula and Weisiopsis, are discussed. The new genus Indopottia may be placed in the tribe Hyophileae.     

Weight loss of the female during the first brood as a factor influencing second brood initiation in Great Tits Parus major and Blue Tits P. caeruleus

We tested the hypothesis that the weight lost by female Great and Blue Tits Parus major and P. caeruleus while raising their first brood influences their ability to start a second brood. The evening weight of female parents was recorded when the nestlings were 5 and 13 days old, in different years and habitats. Several predictions were tested: (1) both species lose weight while raising nestlings and Great Tit females which start a second brood lose less weight than females which do not; (2) differences in the average weight lost between years and areas correlate with differences in the proportion of second broods; (3) the relative weight loss in Blue Tits, which only rarely undertake second broods, is higher than in Great Tits in which second broods are more common. Other factors also are related to the probability of undertaking a second brood: more second broods are undertaken by more successful females, adult females and females that lay earlier.
The comparison of Great and Blue Tits suggests that the two species use different reproductive strategies.     

Anatomy in Toledonia warenella n. sp. (Gastropoda: Opisthobranchia: Diaphanidae) visualized by three-dimensional reconstruction

Abstract. A new species in the cephalaspidean family Diaphanidae, Toledonia warenella n. sp., is described from New South Wales, Australia. Three-dimensional, computer-aided reconstructions of the anatomy, based on serial histological sections, show that T. warenella n. sp. has some features in common with other diaphanids, including lack of jaws, gizzard plates, or an operculum. A gill was not detected in the mantle cavity, which is dominated by large, triangular, opposed ciliary bands and a kidney with lobed edges. The buccal mass is large with thick, muscular walls, perhaps indicative of a suctorial feeding behavior. Comparison with other diaphanid genera was hindered by lack of detailed published anatomical data, but shell and radula morphology suggests a close relationship between the new species and the polar genera Toledonia and Bogasonia (members of Toledoniinae), and for this reason, it is provisionally included in Toledonia. The systematics of Diaphanidae are addressed in the light of the anatomical data presented here.     

Testes investment and spawning mode in pipefishes and seahorses (Syngnathidae)

Externally fertilizing fishes are predicted to invest heavily in testes, because large numbers of sperm should be favoured by the high risk of sperm competition from sneaker males, and/or the dilution of ejaculates when shed into open water. Using museum specimens, we measured testes mass and body mass of 83 mature males, belonging to 21 genera of the family Syngnathidae (pipefishes and seahorses). In this family all species show paternal care, ranging in degree from eggs being attached to the skin of the male, to eggs being completely enclosed and nurtured within a brood pouch. The former, 'unprotected' group, is thought to have external fertilization, whereas in the latter, 'protected' group, males fertilize the eggs internally in their brood pouch. Smaller relative testes investment was thus predicted for genera that have protected compared with unprotected brood care. However, we found this not to be the case. Instead, all genera showed the same relationship between testes and body mass, regardless of brooding type. The possible implications of this surprising result are discussed, including the possibility that the mode of fertilization might have been misjudged for the pouchless syngnathids.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 369–376.     

Hydrodynamic sorting and ecology of a Pleistocene mammalian assemblage from California (U.S.A.)

Bulk sediment samples and surface collections were made from deltaic distributary channel deposits for a paleoecological investigation in the Late Pleistocene Montezuma Formation at Rodeo, California (U.S.A.). Over 1300 kg of bulk samples were screenwashed, and all particles greater than 1.3 mm were saved for analysis. About 3400 identifiable vertebrate specimens of 36 genera (40 species) were recovered. Variations from the expected per cent preservation for selected skeletal elements of small mammal general (N = 1889), for elements of nine rodent genera compared (N = 1136), for cheek teeth of six rodent genera (N = 447), and sediment particle size distribution of a representative locality (464 kg sample) provide qualitative and quantitative information about the effects of hydrodynamic sorting on the preservation of small mammal fossils. Elements which are small, long, and slender, or have large surface to volume ratios are extremely rare. Frequency of preservation and size of cheek teeth decrease in the order: M1, M2, P4-M3, P3. The greatest mass of sediment is in the 1.3–1.4 mm interval where 25% of the identifiable mammal bones and teeth appear. About 80% of the fossils are in the 1.3–3.0 mm range.Hydrodynamic sorting is responsible for the low per cent preservation and relative abundance of each of three species from the Rodeo site (Reithrodontomys raviventris, Scapanus latimanus, and Sorex sp.). Size and shape of skeletal elements are the critical factors, not distance of transport. To ascertain if a species belonged to the community near the site of deposition and to determine its original relative abundance there requires study of many factors in addition to sorting.     

The internal-brooding apparatus in the bryozoan genus Cauloramphus (Cheilostomata: Calloporidae) and its inferred homology to ovicells

We studied by SEM the external morphology of the ooecium in eight bryozoans of the genus Cauloramphus (Cheilostomata, Calloporidae): C. spinifer, C. variegatus, C. magnus, C. multiavicularia, C. tortilis, C. cryptoarmatus, C. niger, and C. multispinosus, and by sectioning and light microscopy the anatomy of the brooding apparatus of C. spinifer, C. cryptoarmatus, and C. niger. These species all have a brood sac, formed by invagination of the non-calcified distal body wall of the maternal zooid, located in the distal half of the maternal (egg-producing) autozooid, and a vestigial, maternally budded kenozooidal ooecium. The brood sac comprises a main chamber and a long passage (neck) opening externally independently of the introvert. The non-calcified portion of the maternal distal wall between the neck and tip of the zooidal operculum is involved in closing and opening the brood sac, and contains both musculature and a reduced sclerite that suggest homology with the ooecial vesicle of a hyperstomial ovicell. We interpret the brooding apparatus in Cauloramphus as a highly modified form of cheilostome hyperstomial ovicell, as both types share 1) a brood chamber bounded by 2) the ooecium and 3) a component of the distal wall of the maternal zooid. We discuss Cauloramphus as a hypothetical penultimate stage in ovicell reduction in calloporid bryozoans. We suggest that the internal-brooding genus Gontarella, of uncertain taxonomic affinities, is actually a calloporid and represents the ultimate stage in which no trace of the ooecium remains. Internal brooding apparently evolved several times independently within the Calloporidae.     

Comparing applesnails with oranges: the need to standardize measuring techniques when studying <Emphasis Type="Italic">Pomacea</Emphasis>

Although invaders come in all shapes and sizes, several mollusks have recently achieved notoriety as both economically and ecologically costly invaders. Applesnails of the genus Pomacea get their name from reaching the size of an apple. Native to South America, the species P. insularum has recently established reproducing, and potentially invasive, populations in Texas, Alabama, Georgia, and Florida. In contrast to the widely invasive golden applesnail (P. canaliculata), few studies of the channeled species P. insularum exist. In studying similar invasive applesnail species, scientists use several methods of measurement. We have explored the relationships among shell height, operculum width, and weight among juvenile and adult P. insularum and tested their inter-measurer reliability. We also investigated the use of shell height, shell length, and operculum width measurements in P. canaliculata studies and observed whether or not those studies defined their measurements. We found that operculum width served as a significantly more reliable measure among researchers. Furthermore, operculum width better predicted weight than shell height. The majority of articles that measured P. canaliculata did not define their measurements, which may cause problems when comparing studies between native and exotic populations or when comparing the two species. We recommend that future studies of P. insularum use operculum width to measure snails and explore a possible sex dimorphism in the operculum width of adult P. insularum.