首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The morphology and development of the larval oral apparatus of Rana dalmatina, Bombina variegata, Bufo bufo, and Bufo viridis are described and compared using scanning electron microscopy. The species show different arrangements of the mouthparts. The small oral apparatus of R. dalmatina larvae has three labial tooth rows on the upper labium, while there are four tooth rows on the lower labium with a medial gap in row proximal to the mouth. The margins of the oral apparatus are defined by papillae that encircle the lower labium. B. variegata tadpoles have two upper labial tooth rows and three lower labial tooth rows that are uninterrupted, unlike the ones of R. dalmatina. The mouth is encircled by papillae that are larger than those of R. dalmatina. The oral discs of tadpoles of both B. bufo and B. viridis are similar. They are defined by two upper labial tooth rows (the second of which is interrupted by a medial gap) and by three lower tooth rows that differ in lengths in the two Bufo species. Both species develop papillae on the mouth angles and in two rows on the upper labium. Some morphological differences among the oral discs of R. dalmatina, B. variegata, B. bufo, and B. viridis tadpoles can be attributed to phylogenetic differences, but most can be related to their varying feeding habits and/or to their dietary specializations.  相似文献   

2.
ABSTRACT. Described herein are the morphology and certain morphogenetic stages of a new freshwater ciliate species, Deviata polycirrata n. sp., and of Deviata bacilliformis recorded in the soil of a dried temporary pond from Argentina. Ciliates were studied alive and after silver impregnation with Protargol. Deviata polycirrata n. sp. measures 130–180 × 45–70 μm in vivo. The species possesses 8–9 long cirral rows on the right and 9–13 on the left of the oral zone, and 3 dorsal rows of dikinetids. The adoral zone is composed of 39–48 membranelles. There are four macronuclear nodules and usually two micronuclei. A single contractile vacuole is located equatorially on the left body margin. This new species mainly differs from its congeners in having a higher number of cirral rows, the three long dorsal rows of dikinetids (vs. usually one to two dorsal rows of dikinetids), and a higher number of adoral membranelles. The other species reported here, D. bacilliformis, is recorded for the first time in Argentina. Unlike previous observations on this species, on the dorsal surface there are cirral rows that are preceded by cilia (combined cirral rows), and stomatogenesis begins with the proliferation of non‐ciliferous basal bodies some distance posterior to the buccal vertex.  相似文献   

3.
The systematic position of Orbiniidae within Polychaeta is still uncertain. In order to provide additional comparative data, we investigated the chaetal arrangement in this family, which is considered valuable for polychaete systematics. Specimens of Scoloplos armiger, Orbinia latreillii, and Pettibonella multiuncinata were examined by SEM and serial sections analysed by computer aided 3D-reconstructions. The obtained data suggest that the chaetal arrangement of Orbiniidae resembles that of other sedentary polychaetes in only a few respects. Transverse rows are only present in the main, anterior part of the chaetal patches of thoracic neuropods. The position of the formative site indicates homology with the transverse rows of several sedentary polychaete taxa. The chaetal patches thus differ significantly from those known in Apistobranchidae. Independent rows with an own caudal formative site, which run along the caudoventral edge of the chaetal patches, resemble the neuropodial ventral longitudinal rows known in Spionidae and related taxa. The abdominal neuropodia of S. armiger and O. latreillii bear longitudinal rows of chaetae. These are reorientated during ontogenetic chaetiger transformation and become the transverse rows of the thoracic chaetal patches. 3D reconstruction of S. armiger revealed that the notopodial chaetal bundles are organized in rows as well. Notopodia and abdominal neuropodia bear deep reaching supportive chaetae. They are the first chaetae formed during neuropodial development and reside dorsally to the longitudinal row of capillary chaetae. Neither position nor structure indicates homology with the supportive chaetae of other sedentary polychaetes. Spionidae and related taxa are thus the only sedentary polychaetes, which specifically resemble Orbiniidae in certain aspects of their chaetal arrangement. Dedicated to Prof. Dr. Wilfried Westheide on the occasion of his 70th birthday.  相似文献   

4.
A terrestrial oxytrichid ciliate Paraparentocirrus sibillinensis n. gen., n. sp., which was found in soil samples of a beech forest stand within the National Park of Sibillini Mountains, Italy, was investigated using live observation and protargol impregnation. The morphology of interphase, morphogenesis, and molecular phylogeny inferred from SSU rDNA sequences of this ciliate were studied. Paraparentocirrus n. gen., is mainly characterized by a semirigid body, an undulating membrane in the Oxytricha pattern, six fronto‐ventral (FV) rows, the absence of transverse cirri, one right and one left row of marginal cirri, four dorsal kineties, two dorsomarginal rows, and caudal cirri at the end of dorsal kinety 4. During morphogenesis, oral primordia develop through the proliferation of basal bodies from some cirri of FV rows 4 and 5, and FV row 6 takes part in the anlagen formation of the proter. The dorsal morphogenesis was typical of oxytrichids, with simple fragmentation of dorsal kinety 3, and the dorsomarginal rows developed from the right marginal row. Phylogenetic analyses based on the SSU rDNA sequences support the classification of this new genus in the stylonychines.  相似文献   

5.
Sinocyclocheilus zhenfengensis sp. nov. is a new species from an underground water environment in a karst cave located in Beipanjiang River of the Pearl River Basin in Shuangrufeng (Double Breasts Hill) Scenic, Etian Village, Zhexiang Township, Zhenfeng County, Guizhou Province, Southwest China. The new species has eyes, its body is completely scaled, an anteriorly directed bulge has formed on the back of its head, and a long pectoral fin exceeds the pelvic fin insertion. The body of the new species is apparently similar to that of S. bicornutus, but differs in scale rows above the lateral line, scale rows below the lateral line, snout length, and eye diameter. Phylogenetic reconstruction of the cytochrome b gene using the maximum parsimony (MP) and Bayesian inference (BI) methods indicates that S. zhenfengensis is closely related to S. bicornutus, S. tianeensis, S. jiuxuensis, and S. altishoulderus; however, it differs in terms of eye size, lateral line scales, scale rows above and below the lateral line.  相似文献   

6.
The morphology and morphogenesis of a new ciliate species, Neobakuella aenigmatica n. sp., which was discovered in an estuary in Korea, were investigated, using live observation, protargol impregnation, and scanning electron microscopy. This new species is characterized by a large (185–300 × 55–105 μm in vivo), elongate‐ellipsoidal, flexible but not contractile body. It has ellipsoidal, yellowish cortical granules, 1.3 × 1.0 μm in size. The species has invariably 3 frontal and 2 frontoterminal cirri, about 5–10 buccal and 1–6 parabuccal cirri, 7 midventral rows, and 1 right and 2–4 left marginal rows. The outer left marginal row(s) consists of 1–7 short rows of cirri. The nuclear apparatus comprises 130 macronuclear nodules and 2 spherical micronuclei on average. The dorsal ciliature consists of 3 dorsal kineties. The leftmost left marginal row(s) likely develops from anlagen originating from both the rightmost and leftmost left marginal row(s). The molecular phylogenetic tree based on SSU rDNA suggests the nonmonophyly of the genus Neobakuella.  相似文献   

7.
Three sphaerodorid species new to science are described from a manganese nodule area in abyssal depths of around 4150 m in the Peru Basin in the eastern South Pacific. Sphaerodoridium campanulata sp. n. is isolated within the genus, having, apart from spherical macrotubercles, additional dorsal stalked bell-shaped papillae, not previously described. Sphaerodoropsis discolis sp. n. is a species with four rows of dorsal macrotubercles and two pairs of lateral antennae. Sphaerodoropsis translucida sp. n. has six to seven rows of dorsal macrotubercles arrayed in two transverse rows per segment and two pairs of lateral antennae. A brief discussion points to the close relationship between Clavodorum and Sphaerodoridium, and to the present state of Sphaerodoropsis, being inhomogeneous in the characters of the arrangement of the dorsal macrotubercles and the numbers of the lateral antennae. An overview on the latter genus, with an attempt to subdivide it, is given.  相似文献   

8.
The development of comb rows in larval and adult Mnemiopsis leidyi and adult Pleurobrachia pileus is compared to regeneration of comb plates in these ctenophores. Late gastrula embryos and recently hatched cydippid larvae of Mnemiopsis have five comb plates in subsagittal rows and six comb plates in subtentacular rows. Subsagittal rows develop a new (sixth) comb plate and both types of rows add plates at similar rates until larvae reach the transition to the lobate form at ~5 mm size. New plate formation then accelerates in subsagittal rows that later extend on the growing oral lobes to become twice the length of subtentacular rows. Interplate ciliated grooves (ICGs) develop in an aboral‐oral direction along comb rows, but ICG formation itself proceeds from oral to aboral between plates. New comb plates in Mnemiopsis larvae are added at both aboral and oral ends of rows. At aboral ends, new plates arise as during regeneration: local widening of a ciliated groove followed by formation of a short split plate that grows longer and wider and joins into a common plate. At oral ends, new plates arise as a single tuft of cilia before an ICG appears. Adult Mnemiopsis continue to make new plates at both ends of rows. The frequency of new aboral plate formation varies in the eight rows of an animal and seems unrelated to body size. In Pleurobrachia that lack ICGs, new comb plates at aboral ends arise between the first and second plates as a single small nonsplit plate, located either on the row midline or off‐axis toward the subtentacular plane. As the new (now second) plate grows larger, its distance from the first and third plates increases. Size of the new second plate varies within the eight rows of the same animal, indicating asynchronous formation of plates as in Mnemiopsis. New oral plates arise as in Mnemiopsis. The different modes of comb plate formation in Mnemiopsis versus Pleurobrachia are accounted for by differences in mesogleal firmness and mechanisms of ciliary coordination. In both cases, the body of a growing ctenophore is supplied with additional comb plates centripetally from opposite ends of the comb rows. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.  相似文献   

9.
Womersleya monanthos (J. Agardh) Papenfuss is typically an epiphyte of larger brown and red algae that are common in drift along the southeastern coasts of Australia. A hitherto little-known member of the Phycodrys group of the Nitophylloideae, its reproductive features have been studied in detail and its taxonomic position clarified. Blades are polystromatic throughout and lack veins or nerves, with blades originating from apical cells of primary and second-order cell rows. Intercalary cell divisions take place in primary cell rows and all other branch orders, with third-order laterals arising both abaxially and adaxially on cells of second-order rows. Fertile central cells bear procarps on pericentral cells on both sides of the blade, the procarps consisting of two 4-celled carpogonial branches and a single central group of sterile cells that enlarge and persist at the distal end of a bicampanulate fusion cell at maturity. Spermatangia and tetrasporangia form in circular subapical sori on both sides of the blade or in marginal lobes or proliferations. After comparing it to other members of the Phycodrys group, we conclude that Womersleya is a monotypic genus well distinguished from other genera and with probable closest affinities to the Northern Hemisphere Polyneura, Erythroglossum and Sorella, as well as the Australian endemic, Crassilingua.  相似文献   

10.
In Pleurotricha lanceolata, the ventral somatic infraciliature presents 13 frontoventral cirri, 5 transverse cirri, one row with 18–19 left marginal cirri and two rows of right marginal cirri of different length. On the dorsal side there are six longitudinal rows of dorsal bristles, four of them bipolar and the other two less than half body length. The oral infraciliature includes the adoral zone of membranelles, with 45–55 membranelles of three or four rows of kinetosomes each, and two undulating membranes (paroral and endoral membranes), each with two rows of kinetosomes. Some structures of the oral and somatic fibrillar systems have also been examined and are similar to those described in other species of hypotrichous ciliates.  相似文献   

11.
Summary The cell division pattern of the germ band of Cherax destructor is described from gastrulation to segmentation, limb bud formation, and early neurogenesis. The naupliar segments are formed almost simultaneously from scattered ectoderm cells arranged in a V-shaped germ disc, anterior to the blastopore. No specific cell division pattern is recognisable. The post-naupliar segments are formed successively from front to rear. Most post-naupliar material is budded by a ring of about 39 to 46 ectoteloblasts, which are differentiated successively and in situ in front of the telson ectoderm. The ectoteloblasts give rise to 15 descendant cell rows by unequal divisions in an anterior direction, following a mediolateral mitotic wave. Scattered blastoderm cells of non-ectoteloblastic origin in front of the ectoteloblast descendants and behind the mandibular region are also arranged in rows. Despite their different origins, teloblastic and non-teloblastic rows cleave twice by mediolateral mitotic waves to form 4 regular descendant rows each. Thereafter, the resulting grid-like pattern is dissolved by stereotyped differential cleavages. Neuroblasts are formed during these differential cleavages and segmentation becomes visible. Each ectoderm row represents a parasegmental unit. Therefore, the segmental boundary lies within the area covered by the descendants of 1 row. Segmental structures (limbs, ganglia) are composed of derivatives of 2 ectoderm rows. The results are compared with the early development of other crustaceans and insects in relation to mechanisms of germ band formation, segmentation, neurogenesis, and evolution.  相似文献   

12.
The morphology and molecular phylogeny of a soil hypotrich ciliate, Pseudourostyla guizhouensis sp. nov., collected from southern China, were investigated. Pseudourostyla guizhouensis sp. nov. has an elongate elliptical body measuring 180–310 × 65–85 μm in vivo; invariably two right and three or four left marginal rows; six or seven dorsal kineties; adoral zone consisting of 57–70 membranelles; 12–16 frontal cirri, one buccal cirrus, 13–20 midventral pairs, two frontoterminal cirri, two pretransverse cirri, and five to seven transverse cirri. Morphogenesis during physiological regeneration indicates that the marginal rows of each side originate from a common anlage that differentiates into several rows. Molecular phylogenetic analysis based on SSU rDNA sequence data reveals that Pguizhouensis sp. nov. clusters with the type species P. cristata (Jerka‐Dziadosz, 1964) Borror, 1972 and that the genus Pseudourostyla is monophyletic. The morphological characters of another soil hypotrich ciliate, Hemicycliostyla franzi (Foissner, 1987) Paiva et al., 2012, are also described based on a Chinese (Guizhou) population.  相似文献   

13.
The morphology, morphogenesis, and 18S rRNA gene sequence of a soil hypotrichous ciliate Perisincirra paucicirrata, isolated from north China, were investigated. Perisincirra paucicirrata differs from its congeners in: (1) having a body length to width ratio in vivo of 4:1, (2) its adoral zone occupying between 15% and 25% of the total body length, and (3) the presence of two parabuccal cirri, three left (with 10–16 cirri each) and two right marginal rows (with 14–24 cirri each), and three dorsal kineties. Our study offers a first attempt to begin to map the morphogenetic processes of the genus, which are mainly characterised by the following: the formation of four frontal ventral transverse anlagens for each daughter cell, with the proter's anlage I originating from the reorganised anterior part of the parental paroral; the paroral and endoral anlage developed from the reorganised old endoral and do not contribute the first frontal cirrus; the frontoventral transverse anlage I contributing the left frontal cirrus; anlage II generating the middle frontal and the buccal cirri; anlage III developing the right frontal cirrus and the anterior parabuccal cirrus; and anlage IV contributing the posterior parabuccal cirrus. As an additional contribution, we judge that the inner one or the two right rows of P. kahli and P. longicirrata are marginal rows. Phylogenetic analysis based on SSU rDNA sequences suggests that Perisincirra is related to sporadotrichids, but provides no credible evidence for its taxonomic position.  相似文献   

14.
15.
Dicroglossum gen. nov. (Delesseriaceae, Ceramiales) is a monotypic genus based on Delesseria crispatula, a species originally described by Harvey for plants collected from southwestern Western Australia. Distinctive features of the new genus include exogenous indeterminate branches; growth by means of a single transversely dividing, apical cell; absence of intercalary divisions in the primary, secondary, and tertiary cell rows; lateral pericentral cells not transversely divided; not all cells of the secondary cell rows producing tertiary cells rows; all tertiary initials reaching the thallus margin; midrib present but lateral nerves absent; determinate lateral bladelets arising endogenously; blades monostromatic, except, at the midrib; carpogonial branches restricted to primary cell rows, on both surfaces of unmodified blades; procarps produced on both blade surfaces, each procarp consisting of a supporting cell that bears two four-celled carpogonial branches and one sterile-cell group of three to four cells; and tetrasporangia borne in two layers, separated by a central row of sterile cells. The combination of exogenous indeterminate branching and bicarpogonial procarps is considered to warrant the recognition of a new tribe, the Dicroglosseae, within the subfamily Delesserioideae.  相似文献   

16.
A new cyprinid fishGarra manipurensis is described from the Manipur River of Manipur State, India. The species differs fromG. annandalei Hora of Darjeeling Himalayas in the interorbital distance, number of rows of scales and position of vent. The fish is also different fromG. lissorhynchus (McClelland) of the Brahmaputra Drainage and the Assam Himalayas in the coloration of dorsal and caudal fins and scales on the belly.  相似文献   

17.
‘Giant race’ stem nematode (Ditylenchus dipsaci) was well controlled in spring beans (Vicia faba) by up to 5 kg aldicarb or carbofuran ha-1 applied to the seed furrows at sowing. Carbofuran was rather more effective in the clay loam soil used than was aldicarb. The best treatments almost eliminated injury to the stems and nematode infestation in the harvested seed. Similarly applied, oxamyl and fenamiphos were less effective and phorate, dimethoate and disulfoton were ineffective. Applying part of the dosage of an effective nematicide to the seed furrows and part along the plant rows mid-season was no more effective and was sometimes less effective than applying the whole dose to the seed furrows. Treating the plant rows mid-season with aldicarb or phoxim sometimes enhanced control but thiabendazole applied thus did not. Seed furrow applications of aldicarb or carbofuran were much less effective in controlling the nematodes in winter beans and seed dressings were less effective than seed furrow treatments. In one experiment, in plots in which aldicarb or oxamyl had been applied to the seed furrows, phoxim or thiabendazole applied over the rows of plants, enhanced nematode control. In two other experiments, thiabendazole was ineffective when applied in this way or when applied as a combined soil and plant treatment.  相似文献   

18.
Gerres methueni Regan, 1920, for many years identified asG. rappi (Barnard, 1927), is redescribed as a senior synonym of the latter species, following examination of two syntypes of the former and comparative material from South Africa and Madagascar.Gerres methueni is characterized by prominent dark stripes along the scale rows above the lateral line and the 4 or 5 rows immediately below it, 5–17 small scales on the preopercular flange, arranged in 1–3 scale row(s) at the corner, 42–44 pored lateral line scales+3–5 additional pored scales on the scaly sheath of the caudal fin base, 41/2–51/2 scales between the fifth dorsal fin spine base and lateral line, and second dorsal fin spine length equal to or slightly shorter than the third dorsal fin spine length.Gerres methueni is currently known from South Africa, southern Mozambique and Madagascar, being endemic in those areas.  相似文献   

19.
Morphology, cirral pattern, and morphogenesis of the new saline soil hypotrich, Gonostomum sinicum nov. spec. collected from Longfeng Wetland in Daqing, north China, were studied, using detailed live observations and protargol‐stained specimens. The new species is characterized as follows: (i) a size in vivo of 100–125 × 30–40 μm, (ii) colorless cortical granules, 0.5 μm across, arranged in short rows, (iii) an adoral zone composed of 28–33 membranelles, (iv) three or four frontoventral rows, one of which extends onto the postoral area, (v) left and right marginal rows composed of 18–27 and 21–35, cirri, respectively, and (vi) usually two transverse cirri. Morphogenesis is as usual for the genus Gonostomum, i.e. the cirral primordia II–VI are primary primordia which split into two sets for proter and opisthe in division middle stages, except for anlage I which develops independently. However, the number of frontoventral transverse anlagen is either five or six not only in different individuals but even in proter and opisthe of the same divider. The phylogenetic analyses based on SSU rDNA sequences showed that the genus Gonostomum is nonmonophyletic, indicating that the patterns of cirri and dorsal kineties are homoplasious characters. The new species G. sinicum nov. spec. is perhaps closely related to Cotterillia bromelicola and two congeners.  相似文献   

20.
A new marine benthic, sand‐dwelling Prorocentrum species from the temperate region of the Pacific coast of British Columbia, Canada, is described using LM and EM and molecular phylogenetic analyses. The cells have a broad oval shape, 40.0–55.0 μm long and 30.0–47.5 μm wide, and a wide U‐shaped periflagellar area on the right thecal plate. The left thecal plate consists of a straighter apical outline in the form of a raised ridge. Five to six delicate apical spines in the center of the periflagellar area are present. The nucleus is located in the posterior region of the cell, and a conspicuous pusule is located in the anterior region of the cell. The cells have golden‐brown chloroplasts with a compound, intrachloroplast pyrenoid that lacks a starch sheath. The thecal plates are smooth with round pores of two different sizes. The larger pores are arranged in a specific pattern of radial rows that are evenly spaced around the plate periphery and of irregular rows (or double rows) that form an incomplete “V” at the apical end of the plates. Large pores are absent in the center of the left and right thecal plates. The intercalary band is striated transversely and also has faint horizontal striations. Trichocysts and two types of mucocysts are present. The molecular phylogenetic position of Prorocentrum tsawwassenense sp. nov. was inferred using SSU rDNA sequences. This new species branched with high support in a Prorocentrum clade containing both benthic and planktonic species.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号