两种石磺齿舌形态差异分析

显微观察了瘤背石磺(Onchidiumstruma)和石磺(O. verruculatum)齿舌的形态结构。运用差异系数法对两种石磺齿舌参数进行比较分析。利用SPSS10.0对瘤背石磺、石磺齿舌参数(齿舌长、齿舌头宽、齿舌中宽、齿舌尾宽、横列数、每排最少齿片数和每排最多齿片数)与个体参数(体长、体宽、体高、足长、足宽和体重)作回归分析。结果表明,两种石磺齿舌都很发达,外观呈长统靴状;齿片排成许多横列,每一横列均有中央齿一枚,侧齿若干无缘齿;两种石磺的齿舌头宽、齿舌中宽和齿舌尾宽差异极显著,但差异系数小于1.28,认为两种石磺的齿片形态存在明显的种间差异,但齿舌参数不适合作为石磺属贝类的分类依据;瘤背石磺的体宽和石磺的体重在评估各自齿舌生物学性状方面起到比较重要的作用。     

General morphology and ultrastructure of the radula of Testudinalia testudinalis (O. F. Müller, 1776) (Patellogastropoda,Gastropoda)

The radular morphology of the patellid species Testudinalia testudinalis (O. F. Müller, 1776) from the White Sea was studied using light, electron, and confocal microscopy. The radula is of the docoglossan type with four teeth per row and consisting of six zones. We characterize teeth formation in T. testidinalis as follows: one tooth is formed by numerous and extremely narrow odontoblasts through apocrine secretion; this initially formed tooth consists of numerous vesicles; the synthetic apparatus of the odontoblasts is localized in the apical and central parts of the cells throughout the cytoplasm and is penetrated by microtubules which are involved in the transport of the synthesized products to the apical part of the odontoblast; the newly formed teeth consist of unpolymerized chitin. Mitotic activity is located in the lateral parts of the formation zone. The first four rows contain an irregular arrangement of teeth, but the radular teeth are regularly arranged after the fifth row. The irregularly arranged teeth early on could be a consequence of the asynchronous formation of teeth and the distance between the odontoblasts and the membranoblasts. The morphological data obtained significantly expands our knowledge of the morphological diversity of the radula formation in Gastropoda.     

Main patterns of radula formation and ontogeny in Gastropoda

Gastropoda is morphologically highly variable and broadly distributed group of mollusks. Due to the high morphological and functional diversity of the feeding apparatus gastropods follow a broad range of feeding strategies: from detritivory to highly specialized predation. The feeding apparatus includes the buccal armaments: jaw(s) and radula. The radula comprises a chitinous ribbon with teeth arranged in transverse and longitudinal rows. A unique characteristic of the radula is its continuous renewal during the entire life of a mollusk. The teeth and the membrane are continuously synthesized in the blind end of the radular sac and are shifted forward to the working zone, while the teeth harden and are mineralized on the way. Despite the similarity of the general mechanism of the radula formation in gastropods, some phylogenetically determined features can be identified in different phylogenetic lineages. These mainly concern shape, size, and number of the odontoblasts forming a single tooth. The radular morphology depends on the shape of the formation zone and the morphology of the subradular epithelium. The radula first appears at the pre- and posttorsional veliger stages as an invagination of the buccal epithelium of the larval anterior gut. The larval radular sac is lined with uniform undifferentiated cells. Each major phylogenetic lineage is characterized by a specific larval radula type. Thus, the docoglossan radula of Patellogastropoda is characterized by initially three and then five teeth in a transverse row. The larval rhipidoglossan radula has seven teeth in a row with differentiation into central, lateral, and marginal teeth and later is transformed into the adult radula morphology by the addition of lateral and especially marginal teeth. The taenioglossan radula of Caenogastropoda is nearly immediately formed in adult configuration with seven teeth in a row.     

A new endangered species of Megaleporinus (Characiformes: Anostomidae) from the Rio de Contas basin,eastern Brazil

A new species of Megaleporinus is described from the Rio de Contas, a coastal drainage of eastern Brazil, and its phylogenetic relationships are studied using molecular data. The new species is unique among Anostomidae by possessing two exclusive features: an irregular dark longitudinal stripe from supracleithrum to second midlateral blotch and anterior cranial fontanel partially closed. In addition, the new species is diagnosed by having three premaxillary teeth, three dentary teeth, 37 or 38 scales in lateral line, 16 scale rows around caudal peduncle, three dark midlateral blotches on body, and red fins in life. The new species is closely related to M. obtusidens from the São Francisco basin, corroborating previous studies that indicated that the latter represents a species complex as currently defined. The new species exhibits the first rib enlarged in mature males, a feature described for some congeners. The new species is herein considered to be Endangered under the IUCN criteria.     

A new type of gastropod proboscis: the foregut of Hastula bacillus (Gastropoda: Terebridae)

Hastula bacillus (Deshayes) is a small terebrid gastropod which inhabits sandy surf beaches in southern Thailand, where it feeds upon spionid polychaetes. It possesses a foregut anatomy unlike that of any other gastropod. An elongate arborescent muscular organ, known as the accessory proboscis structure, is extended through the mouth during foraging. When retracted, it is folded into an 's' shape in the permanent rhynchodeum. The accessory proboscis structure bears numerous tufts of short, stiff cilia which are associated with pairs or triplets of dome-like structures. It is suggested that the structures may be chemosensory and concerned with prey location. Hastula bacillus also possesses a retractable labial tube, a long proboscis and buccal tube, dart-shaped radular teeth, an odontophore, an accessory salivary gland, a pair of salivary glands and a well-developed venom gland with muscular bulb. A comparison with other terebrid species suggests that H. bacillus is the most plesiomorphic taxon yet described from the family.     

PHYLLODESMIUM GUAMENSIS (NUDIBRANCHIA: AEOLIDOIDEA), A NEW SPECIES FROM GUAM(MICRONESIA)

A new species of Phyllodesmium (Aeolidoidea) from Guam (Micronesia)is described. Phyllodesmium guamensis n.sp. is characterizedby having two rows of denticles in the radular teeth, this beingdifferent from the previously described species of the genus.The shape of the teeth, however, is identical in all the speciesof the genus, and unique among aeolids. Furthermore, P. guamensispossesses a double row of cerata in the precardiac cluster andup to 10 post-cardiac ceratal rows. Also, P. guamensis showsa very dense accumulation of zooxanthellae in the ceratal digestivegland, which is ramified inside the cerata. This species feedson at least three species of the soft coral Sinularia: S. polydactyla,S. maxima and a third, undescribed species. The aeolid matchesthe colour of its prey and is cryptic on the soft coral surface. (Received 3 October 1996; accepted 28 April 1997)     

COMPARATIVE MORPHOLOGY OF RADULAR TEETH IN CONUS: OBSERVATIONS WITH SCANNING ELECTRON MICROSCOPY

Radular teeth of 22 Indo-Pacific species of the genus Conus(Neogastropoda: Toxoglossa) were compared. On morphologicalfeatures all can be related to one of three known feeding modes:piscivorous, vermivorous and molluscivorous. Observations arereported on the radular teeth of six piscivores, thirteen vermivoresand three molluscivores. The radular teeth of piscivores areof two general types. In the first, two barbs and a posteriorly-directedprocess with a recurved tip are found at the anterior end. Inthe second, two barbs are located at the anterior end and theshaft is serrated for most of its length. An enlarged posteriorregion (terminal knob) is present in the first and absent inthe second. Molluscivores possess radular teeth with two anteriorbarbs and in some species a serrated shaft or terminal knob.The radular teeth of vermivores, which show much greater interspecificvariation than those of piscivores or molluscivores, are characterizedby one or two anterior barbs and in most species a serratedregion near the apex. A forwardly-projecting cone (basal spur)is usually located on the terminal knob. Piscivores and molluscivoreslack such basal spurs. The radular teeth of Conus are used toconvey a potent venom and hold prey firmly during feeding. Previouslyundescribed morphological features are noted on the teeth ofC. obscurus and C. lividus. Figured here for the first timeare the radular teeth of C. abbreviatus, C. aureus, C. catus,C. litoglyphus, C. pennaceus, C. rattus and C. sponsalis. ^*Present address: Department of Paleontology, University ofCalifornia, Berkeley, California 94720, U.S.A. (Received 2 April 1979;     

17种陆生贝类齿舌的扫描电镜观察及 分类学意义探讨

采用扫描电镜观察了3目10科12属17种陆生贝类的齿舌形态.结果 显示,17种陆生贝类齿舌的中央齿均为1列,侧齿12～218列不等,缘齿0～204列不等.中央齿依齿片上小齿数目分为单齿型、三齿型和多齿型;侧齿与缘齿的形态多样,侧齿齿片上小齿数1～6枚不等,缘齿齿片上小齿数1～10枚不等.结合以往报道的38种陆生贝类齿舌...     

Phylogenetic and systematic study of Korean <Emphasis Type="Italic">Orius</Emphasis> species (Heteroptera: Anthocoridae) on the basis of molecular and morphological data

A phylogenetic and systematic study of Orius species (Heteroptera: Anthocoridae) from Korea has been conducted using both morphological and molecular characters. Thirty morphological character states were coded for 10 strains of 9 species. Five molecular markers, partial cytochrome c oxidase I (COI), cytochrome b (CytB), 16S rRNA (16S), 18S rRNA (18S), and 28S rRNA (28S), from mitochondrial and nuclear genes, were tested. Phylogenetic analyses based on molecular data were conducted by minimum evolution, maximum parsimony, maximum likelihood, and Bayesian phylogenetic (BP) analyses. Analysis of morphological data was performed using the parsimony programs NONA, and the combined dataset of morphological and molecular data was analyzed using BP analyses. The results of this study indicate that use of COI and CytB enabled relatively effective identification of species, whereas the sequences of 16S, 18S and 28S did not enable identification of closely related species such as Orius minutus and O. strigicollis. We discuss the usefulness of the five molecular markers for determining phylogenetic relationships and identifying the species.     

Radula formation in two species of Conoidea (Gastropoda)

The radula is the basic feeding structure in gastropod molluscs and exhibits great morphological diversity that reflects the exceptional anatomical and ecological diversity occurring in these animals. This uniquely molluscan structure is formed in the blind end of the radular sac by specialized cells (membranoblasts and odontoblasts). Secretion type, and the number and shape of the odontoblasts that form each tooth characterize the mode of radula formation. These characteristics vary in different groups of gastropods. Elucidation of this diversity is key to identifying the main patterns of radula formation in Gastropoda. Of particular interest would be a phylogenetically closely related group that is characterized by high variability of the radula. One such group is the large monophyletic superfamily Conoidea, the radula of which is highly variable and may consist of the radular membrane with five teeth per row, or the radular membrane with only two or three teeth per row, or even just two harpoon-like teeth per row without a radular membrane. We studied the radulae of two species of Conoidea (Clavus maestratii Kilburn, Fedosov & Kantor, 2014 [Drilliidae] and, Lophiotoma acuta (Perry, 1811) [Turridae]) using light and electron microscopy. Based on these data and previous studies, we identify the general patterns of the radula formation for all Conoidea: the dorsolateral position of two groups of odontoblasts, uniform size, and shape of odontoblasts, folding of the radula in the radular sac regardless of the radula configuration. The morphology of the subradular epithelium is most likely adaptive to the radula type.     

Electron microscopic studies on radular tooth formation in the snails Helix pomatia L. and Limax flavus L. (Pulmonata,Stylommatophora)

The radular teeth are secreted at the posterior end of the radular gland and move slowly towards the buccal cavity where they start to function. Helix pomatia and Limax flavus were examined to determine whether the newly formed teeth already show their definite species specific shape, or whether they are gradually finished and moulded in the radular gland. Scanning electron micrographs of Helix pomatia show that teeth are secreted in the odontoblast region in their final form. Their surface is still uneven at the outset; the same is true for the newest teeth of Limax flavus. Older teeth ready for use have a smooth surface. This change seems to be brought about by secretory activity of the superior epithelium of the radular sac. Air-dried radulae, previously isolated by KOH maceration, show considerable artefacts at their posterior end. Maceration leads to shrinking of the newest teeth, but does not change their contours. The newly secreted but as yet unhardened teeth become greatly deformed during the drying process.     

MORPHOLOGICAL CHANGES ACCOMPANYING THE TRANSITION FROM JUVENILE (ATMOSPHERIC) TO ADULT (TANK) FORMS IN THE MEXICAN EPIPHYTE TILLANDSIA DEPPEANA (BROMELIACEAE)

Two distinct morphological forms characterize the ontogenetic development of the epiphytic bromeliad Tillandsia deppeana. Juveniles are characterized by a non-impounding rosette of small, linear leaves covered with elaborate trichomes possessing a 4 + 8 + 16 + 64 shield cell pattern. The broader transitional leaves, which form an impounding rosette prior to the initiation of true adult leaves, also possess trichomes with the 4 + 8 + 16 + 64 cell pattern. Adult individuals have large, broad leaves with overlapping, sheathing bases which impound water and debris. These leaves have trichomes with shields exhibiting a 4 + 8 + 32 cell pattern. Trichome density is fairly uniform in the juvenile leaves with trichomes covering 100% of leaf surfaces, whereas in the adult leaves density is high at the base and diminishes significantly toward the apex. Stomatal density of both juvenile and adult leaves increases from the base to the apex, although this is most pronounced in the adults. Stomata in the adults are also arranged in longitudinal series parallel and abaxial to parallel rows of mesophyll tissue. The results of this study indicate that juveniles of T. deppeana are more similar morphologically to adult atmospheric-type tillandsioid species than to the tank-forming adults into which they eventually develop.     

Morphological adaptations and plasticity of radular teeth of the Sacoglossa (= Ascoglossa) (Mollusca: Opisthobranchia) in relation to their food plants

The radular teeth of 55 species of Sacoglossa (= Ascoglossa) (Mollusca: Opisthobranchia) with known diets are classified into three basic groups: triangular, blade-shaped and sabot-shaped. Cell wall composition of the food plant is the single most important factor influencing radular morphology. The algae eaten by sacoglossans have either xylan, mannan or cellulose as their structural wall component. Sabot-shaped teeth are associated with diets of Siphonocladales and Cladophorales, which have cellulose cell walls of a 'crossed fibrillar texture'. Triangular teeth with lateral denticles are associated with diets of Caulerpa or with calcified algae. Most of these have xylan as the major structural polysaccharide. Blade-shaped teeth occur in a large number of species representing a wide variety of diets. It is proposed that the three types of teeth function in different manners. Tooth denticulation is correlated with functional group of the food plant. The radular teeth of Elysia viridis feeding on Codium are longer, wider and have more curved tips than teeth of E. viridis feeding on Chaetomorpha. The teeth of E. viridis transferred from Codium to Chaelomorpha in the laboratory change in shape as well as size.     

Possible imitation of jellyfish by the squid paralarvae of the family Gonatidae (Cephalopoda,oegopsida)

Paralarval behaviour of eight species of the family Gonatidae (Teuthoidea, Cephalopoda) was examined in small 3–1 aquaria on board ship during planktonic surveys, which were carried out above and off the continental slope of the western part of the Bering Sea. Undisturbed paralarvae moved in aquaria with an average frequency of 15–20 mantle contractions per minute. In response to a sudden disturbance (flash of light, impact to the aquarium wall) squids exhibited a defensive body posture, relaxing the mantle and pulling the head with tentacles and arms into the mantle cavity, thereby becoming similar in appearance, size and colour to small jellyfishesAglantha digitalis (Hydromedusae).     

Comparative Enzyme Differentiation in Grass Roots: II PEROXIDASE

Results of histochemical tests for peroxidase activity in sevenspecies of grasses have been reported. The root epidermis ofthe festucoid grasses is characterized by rows of alternatingshorter hair and longer hairless cells which can be recognizedthroughout their development. Peroxidase activity occurred inall the growing cells, but intensified reactions were observedin the hair cell initials in the bases portion of the elongationzone. The panicoid species have a root epidermis in which anycell seems capable of producing a root hair, and in these speciesall cells in the growing regions showed equal peroxidase activity.The close correlation between the differentiations of enzymesand cell types implies that physiological changes occur longbefore the morphological maturation of the tissue.     

Phylogeny of the Asian spiny frog tribe Paini (Family Dicroglossidae) sensu Dubois

The anuran tribe Paini, family Dicroglossidae, is known in this group only from Asia. The phylogenetic relationships and often the taxonomic recognition of species are controversial. In order to stabilize the classification, we used approximately 2100 bp of nuclear (rhodopsin, tyrosinase) and mitochondrial (12S, 16S rRNA) DNA sequence data to infer the phylogenetic relationships of these frogs. Phylogenetic trees reconstructed using Bayesian inference and maximum parsimony methods supported a monophyletic tribe Paini. Two distinct groups (I,II) were recovered with the mtDNA alone and the total concatenated data (mtDNA+nuDNA). The recognition of two genera, Quasipaa and Nanorana, was supported. Group I, Quasipaa, is widespread east of the Hengduan Mountain Ranges and consists of taxa from relatively low elevations in southern China, Vietnam and Laos. Group II, Nanorana, contains a mix of species occurring from high to low elevation predominantly in the Qinghai-Tibetan Plateau and Hengduan Mountain Ranges. The occurrence of frogs at high elevations appears to be a derived ecological condition. The composition of some major species groups based on morphological characteristics strongly conflicts with the molecular analysis. Some possible cryptic species are indicated by the molecular analyses. The incorporation of genetic data from type localities helped to resolve some of the taxonomic problems, although further combined analyses of morphological data from type specimens are required. The two nuDNA gene segments proved to be very informative for resolving higher phylogenetic relationships and more nuclear data should be explored to be more confident in the relationships.     

RADULAR PRODUCTION RATES IN TWO SPECIES OF LACUNA TURTON (GASTROPODA: LITTORINIDAE)

The molluscan radula is a dynamic organ, both in terms of itsuse and production. New rows of teeth are constantly producedat the posterior end of the radula, while older, worn teethare shed anteriorly, producing a dynamic equilibrium. We useda cold-shock to mark the radular ribbon and measure tooth rowproduction rates in two gastropod species, Lacuna vincta (Montagu)and L. vanegata Carpenter. We found that the average tooth rowproduction rate at 10–11°C did not differ betweenthese two species, and was 2.94 (SE = 0.002) rows per day forLacuna vincta and 2.97 (SE = 0 002) for L. vanegata Inter-individualvariability in production rate was very low, and was correlatedwith shell length, smaller individuals had slightly higher productionrates. The total length of the radular nbbon varied greatlyamong individuals, ranging from 47 to 94 (2.57 to 5.68 mm) rowsin L vincta and 53 to 99 rows (2.80 to 7.14 mm) in L vanegata,and was only somewhat correlated with the length of the shelLThis great variability will result in large differences amongindividuals in the time it takes to replace the radula totally,from 14.96 to 35.44 days in L vincta and from 17 43 to 39 69days in L. vanegata. (Received 1 September 1995; accepted 20 November 1995)     

Aeolid nudibranchs (Gastropoda: Opisthobranchia) of the family Tergipedidae from New Zealand waters

Four species of the genus Cuthona Alder & Hancock are recorded for the first time. Two of these species are Cuthona beta (Baba & Abe, 1964) and C. alpha Baba & Hamatani, 1963: although the local specimens differ in some features, principally ceratal arrangement, length of the radula and colour, the differences are considered too slight to warrant separation. The other two are new, being distinguished by a combination of features: C. scintillans sp. nov. by the large size reached (24 mm), rhinophores, oral veil and number of ceratal rows (13), the rounded foot-angles, green diverticula and yellow surface pigmentation, and number of denticles on the largest radular teeth (9); C. reflexa sp. nov. by the simple colouration, short radula (30 teeth), terminal position of the cusp, a very short or no vagina and the renal opening above the anus.
The name Tergipedidae (= Cuthonidae) is given priority and its use reviewed. Three subfamilies are recognized viz. Cuthonellinae, Cuthoninae and Tergipedidinae, each founded on the division of the digestive gland. Thirteen genera are listed, but only seven are firmly established as being distinctive and belonging to the family; one of the remaining six, Guyvalvoria Vayssiere, 1906, is certainly valid, but, because the ceratal arrangement is only superficially known, its place in the family could not be determined.     

Radiation of the land snail genus Sagda (Pulmonata: Sagdidae): comparative morphology, biogeography and ecology of the species of north-central Jamaica

The radiation of the endemic Jamaican land snail genus Sagda is examined through analysis of the comparative shell morphology, anatomy, ecology and biogeography of the four species inhabiting north-central Jamaica: S. centralis sp. nov. , S. spei, S. bondi and S. montegoensis. The species are all rather similar in their morphology and ecology. The shells show some differences in the presence or absence of internal lamellae, the position of the lamellae, the form of the depression in the centre of the base, the regularity of sculpture (low ribs) and the pattern of microsculpture. Slight differences in the form of the radular teeth are found between some species. The structure of the secondary ureter is peculiar: in all species it is open shortly behind the mantle collar, then branches into two closed tubes which open separately on the outside of the mantle collar. Despite its great complexity, the reproductive system is rather uniform among species; differences are seen in the number of pockets that form spines on the spermatophore. The complex, three-branched spermatophore is formed within the entire epiphallar branch of the penis, whereas the appendicular branch apparently assumes the copulatory function. When inactive, all species are found associated with rocks or, less commonly, among leaf litter. Activity occurs primarily at night and mostly on leaf litter rather than rocks. The snails eat dead plant material, including a variety of plant species. All species (with the possible exception of S. montegoensis) are ovoviviparous. They overlap broadly in the range of climates occupied. The geographic ranges of the four species are overlapping, although Sagda bondi has a parapatric distribution in relation to the western species S. grandis. Fossil and subfossil evidence shows that shifts in the ranges of the species have occurred in the late Quaternary; Pleistocene-Holocene environmental changes, habitat destruction by man, and possibly other environmental changes during historical times are probably involved. Radiations of other land snail groups on tropical islands have generally produced greater morphological and ecological differentiation than in Sagda. Allopatric or parapatric species distributions appear to be more common in other land snail radiations.