Comparative spermatology in Plecoptera (Insecta): an ultrastructural investigation on four species

The ultrastructure of spermatozoa of four Plecoptera species, Leuctra fusca Linnaeus, Brachyptera risi (Morton), Taeniopteryx stankovitchi Ikonomov, T. kuehtreiberi (Aubert), was investigated by light microscopy, scanning and transmission electron microscopy, and immunofluorescence microscopy. The spermatozoa of all the species have a complex acrosome, are filiform and flagellate, with a '9+9+2' axoneme flanked by two mitochondrial derivatives. However, the structure shows a certain interspecific heterogeneity. L. fusca has a short conical nucleus in the apical position and an axoneme flanked by two accessory bodies. In the sperm of the Taeniopterygidae, the nucleus is a long cylindrical body which lies between the two mitochondrial derivatives flanking the axoneme for most of its length. Our results suggest a close phylogenetic affinity between Plecoptera and the other orders of Polyneoptera, although the proposed sister-group relationship between Plecoptera and Embioptera cannot be confirmed.     

日本纺织娘的精子超微结构（直翅目：螽斯总科，纺织娘科）

对日本纺织娘Mecopoda nipponensis的精子超微结构进行了透射电镜观察。结果表明：其顶体复合体侧生于细胞核上且包裹了核顶端的部分;细胞核致密,横切面多为新月形或半月形;2蚕豆形副体位于9+9+2轴丝的两侧;线粒体衍生体横切面为椭圆形,其基质几乎完全晶状化;线粒体衍生体一侧的2扁平膜池横切面近S形;轴丝与线粒体衍生体之间有3条连接带,其中中央的一条呈环状;在有些尾部横切面中,质膜之内又有一双层膜把尾部的细胞器围绕起来。     

Comparative spermatology of four species of strepsiptera and comparison with a species of primitive coleoptera (Rhipiphoridae)

The comparative spermatology of 4 strepsipteran species, namely, Xenos moutoni De Buysson, Elenchus tenuicornis (Kirby), Elenchus japonicus Esaki and Hashimoto and Halictophagus chilensis Hofmann, have been studied by transmission electron microscopy. The spermatozoon of all 4 species examined were seen to have: an elongated head characterized by a nucleus with an internal channel of uncondensed chromatin, a one-layered acrosome, and a tail containing a 9 + 9 + 2 axoneme and 2 partially crystallized mitochondrial derivatives. Each sperm, nevertheless, shows a few peculiarities that confirm the taxonomic value of comparative spermatology. In addition, the strepsipteran spermatozoa were seen to have a different organization to that of Pelecotoma fennica Pewkull (Rhipiphoridae, Pelecotominae), which has the typical structure of a coleopteran sperm. It was characterized by a 3-layered acrosomal complex, a tail with a 9 + 9 + 2 axoneme flanked by 2 accessory bodies and 2 mitochondrial derivatives. From the spermatological point of view, primitive Coleoptera cannot be considered to be closely related to Strepsiptera.     

两种草螽精子超微结构比较研究(直翅目,螽斯总科)

比较研究了长翅草螽Conocephalus longipennis与鼻优草螽Euconocephalus nasutus精子的超微结构。两种精子的顶体复合体侧生于核上且包裹了核的一部分;轴丝为典型的9 9 2型;轴丝两侧的副纤维结构前者为2副体,后者为2副微管;线粒体衍生体横切面前者为鞋履形,后者卵圆形;轴丝与线粒体衍生体之间的连接带前者为5条,后者3条;近线粒体衍生体的两扁平膜池在长翅草螽中连接在一起呈飞燕形。     

中华蝈螽与中华螽斯精子超微结构研究(直翅目,螽斯总科)

研究了中华蝈螽Gampsocleis sinensis与中华螽斯Tettigonia chinensis精子的超微结构.两种精子的顶体复合体侧生于核上且包裹了核的一部分,顶体复合体横切面两侧角分离或两侧角与细胞核远离,或仅见其一侧角;中华蝈螽顶体外层在顶体本体两侧角外多呈晕圈状;轴丝为典型的9 9 2型;轴丝两侧的副纤维结构为2副微管;轴丝与线粒体衍生体之间的连接带3条;中华蝈螽有的横切面中两扁平膜池连接在一起;两种精子的中心粒侧体部位具五纵层细胞器.     

暗褐蝈螽与优雅蝈螽精子超微结构的比较研究(直翅目,螽斯科)

研究了暗褐蝈螽Gampsocleis sedakovii(Fischer von Waldheim)和优雅蝈螽G.gratiosa Brunner von Wattenwyl精子的超微结构。这两种蝈螽精子头部的顶体复合体由顶体外层、顶体本体和顶体组成,顶体复合体位于细胞核前端,并包裹部分细胞核;颈部具5纵层细胞器;尾部鞭毛轴丝为典型的9+9+2型,线粒体衍生体部分晶状化。暗褐蝈螽精子较短,顶体复合体夹角较大,精子鞭毛横切面直径稍大;优雅蝈螽精子稍长,顶体复合体夹角较小,精子鞭毛横切面直径较小,两种精子超微结构差异不显著,其生殖隔离机制有待进一步研究。     

Ultrastructural analysis of spermatozoa of Korscheltell us lupulinus L. (Lepidoptera : Hepialidae) and Micropterix calthella L. (Lepidoptera : Micropterigidae)

In Korscheltellus lupulinus (Lepidoptera : Hepialidae), both eusperm and parasperm can be found, whereas Micropterix calthella (Lepidoptera : Micropterigidae) produces only eusperm. The eupyrene sperm in K. lupulinus is 250 μm long. Spermatozoa found in K. lupulinus are very similar to those found in higher Lepidoptera, but the eusperm of M. calthella do not possess similar features. As in other Lepidoptera, the axoneme pattern of K. lupulinus is 9 + 9 + 2. Anteriorly, the axoneme is replaced by a fibrous stem similar to an acrosomal structure; posteriorly it becomes progressively uneven. The sperm of K. lupulinus has other original features. The anterior region of the sperm is rigid and contains the nucleus, which has a longitudinal groove adjacent to the axoneme. The 2 mitochondrial derivatives extend from the posterior end of the nucleus. There are no accessory bodies. Many peripheral cytoplasmic vesicles are present. A thin sheath surrounds the cell. It is thick in the parasperm and made of concentric or spiralling lamellae; it does not have any lacinate appendages.The axoneme of the sperm of M. calthella extends over the entire length of the cell and spirals in a helix around the nucleus. The nucleus is also almost as long as the cell. The 2 mitochondrial derivatives, flanked by accessory bodies, follow this spiralling. The axoneme has a 9 + 2 pattern. The plane, which contains the 2 central microtubules, is at an angle with the median plane of the nucleus.     

瘤背石磺的精子结构

用光学显微镜和透射电子显微镜技术研究了瘤背石磺精子的结构特点,分析了其生理生态适应性以及在肺螺亚纲系统演化中的意义。瘤背石磺的精子由头部、中段和末段组成。头部由奶嘴形的顶体和长圆筒状的细胞核构成。顶体包括顶体囊和顶体构架体两部分;两者的内含物都分布均匀,电子密度稍低于细胞核;顶体基部平整,与核前端之间有一空隙,内含物电子密度极低。细胞核由电子密度高的均匀颗粒物质组成,并出现核泡;核的后端有一"杯形"的凹陷,称为核后窝。中段结构复杂,主要包括一对位于核后窝内的中心粒、轴丝、质膜、线粒体及由线粒体衍生的糖原质螺旋体、基质层和类晶体层等。末段由"9 2"结构的轴丝及外包的质膜组成,无糖原质螺旋体和其它线粒体衍生物。比较瘤背石磺精子与肺螺亚纲其它物种的精子结构,我们认为该物种的精子属于"进化型",是一类在进化地位中比基眼目高等的动物。     

New family characters of larval Plecoptera,with an analysis of the Chloroperlidae: Paraperlinae

Larval structures diagnostic of several Plecoptera families, subfamilies or genera are described and illustrated. They concern the following: distinction of larval Leuctridae from Capniidae; an additional apomorphy of Nemouridae; a synapomorphy of Perlidae and Perlodidae; monophyly of each of the two subfamilies of Chloroperlidae, and the generic limits among Chloroperlidae: Paraperlinae. Paraperla lepnevae Zhiltzova is transferred to Utaperla. Some comments on Notonemouridae are included.     

Sperm ultrastructure and spermiogenesis of Coniopterygidae (Neuroptera, Insecta)

The spermiogenesis and the sperm ultrastructure of several species of Coniopterygidae have been examined. The spermatozoa consist of a three-layered acrosome, an elongated elliptical nucleus, a long flagellum provided with a 9+9+3 axoneme and two mitochondrial derivatives. No accessory bodies were observed. The axoneme exhibits accessory microtubules provided with 13, rather than 16, protofilaments in their tubular wall; the intertubular material is reduced and distributed differently from that observed in other Neuropterida. Sperm axoneme organization supports the isolated position of the family previously proposed on the basis of morphological data.     

Sperm Bundles in the Seminal Vesicle of the Crematogaster victima (Smith) Adult Males (Hymenoptera: Formicidae)

This study establishes the presence of spermatodesm in the seminal vesicles of sexually mature males of Crematogaster victima (Smith). In this species, the spermatozoa are maintained together by an extracellular matrix in which the acrosomal regions are embedded. This characteristic has not yet been observed in any other Aculeata. However, the sperm morphology in this species is similar to that described for other ants. The spermatozoa measure on average 100 μm in length, and the number of sperm per bundle is up to 256. They are composed of a head formed by the acrosome and nucleus; this is followed by the flagellum, which is formed by the centriolar adjunct, an axoneme with a 9?+?9?+?2 microtubule pattern, two mitochondrial derivatives, and two accessory bodies. The acrosome is formed by the acrosomal vesicle and perforatorium. The nucleus is filled with compact chromatin with many areas of thick and non-compacted filaments. Both mitochondrial derivatives have the same shape and diameters. The presence of sperm bundles in sexually mature males differentiates C. victima from other ants; however, the similarities in the sperm ultrastructure support the monophyly of this insect group.     

Sperm ultrastructure in the nudibranch genus Halgerda with reference to other Discodorididae and to Chromodorididae (Mollusca: Opisthobranchia)

Comparative sperm ultrastructure within the molluscan nudibranch genus Halgerda (Discodorididae) was examined for the first time using transmission electron microscopy (TEM), based on 17 of the 35 known species. In addition, observations on two other discodorids are made to facilitate outgroup comparison with Halgerda, including one species of Discodoris (D. boholiensis) and Asteronotus cespitosus (currently accepted as the closest sister taxon to Halgerda). Comparison was also made with some genera of the Chromodorididae in view of sperm similarities. Spermatozoa of all species examined were of the complex, helical, elongate ( approximately 300-400 micro m) type characteristic of most heterobranch gastropods. These cells exhibit the following discrete regions (in anteroposterior sequence) : an acrosomal complex (composed of a rounded, membrane-bound vesicle and a column-like pedestal); a solid, helical nucleus; an elongate, helical midpiece (composed of an axoneme and associated nine coarse fibers, an enveloping mitochondrial derivative of matrix, and paracrystalline materials and glycogen helix); an annular complex; and a short glycogen piece. Of these regions, the midpiece is by far the longest, occupying over 90% of the total sperm length. Comparison with other members of the radula-bearing cryptobranch dorids reveals several sperm similarities to other genera in the clade, particularly those of other Discodorididae and also with the Chromodorididae. Comparison with previously studied genera reveals noteworthy sperm differences within the Discodorididae. The most notable differences are the internal structure of the acrosomal pedestal (long and homogeneous in Halgerda, Discodoris; short and homogeneous in Asteronotus; long and finely striated in Rostanga; oblong with angular electron-lucent striations in Jorunna) and the internal structure of the glycogen piece. The pronounced helical keels of most Halgerda and Discodoris nuclei contrast with the weakly helical nucleus of Asteronotus. Sperm features alone do not provide a means of defining the genus Halgerda or the family Discodorididae nor do they support the monophyletic status of the caryophyllidia-bearing dorids. Important sperm characters such as the acrosome, nucleus, and midpiece can often still be determined from specimens that have been initially fixed in formalin, then stored in ethanol for extended periods of time (i.e., museum material). Of all sperm features, the mitochondrial derivative of the midpiece is the most resistant to long-term fixation : the survival of acrosomal, nuclear, and axonemal components is variable, presumably a factor of prefixation autolysis, varied primary fixation times and temperatures, formalin quality, and duration of alcohol storage.     

Ultrastructure of the spermatozoon of the mosquito Toxorhynchites (Diptera, Culicidae)

The spermatozoon of Toxorhynchites brevipalpis conradti Gruenberg is long and filiform. It contains an anterior nucleus, an axoneme of the 9 + 9 +"1" pattern and two mitochondrial derivatives. Comparison of our observations with bibliographical data shows that spermatozoon ultrastructure is homogeneous in the family Culicidae (Culicinae, Anophelinae and Toxorhyn-chitinae). The 9 + 9 +"1" pattern of the sperm axoneme may be considered a synapomorphy of the Culicidae.     

ULTRASTRUCTURE OF THE MATURE SPERMATOZOA OF THE LAND SNAIL EPIPHRAGMOPHORA TUCUMANENSIS (DOERING, 1874) (GASTROPODA: HELICOIDEA)

The ultrastructure of the sperm of Epiphragmophora tucumanensis(Doering), a pulmonate land snail belonging to the family Xanthonychidae,was examined. The results showed that this spermatozoon presents a similarmorphology to the other advanced stylommatophoran sperm described.The most peculiar characteristic is the form of the nucleus,which is straight instead of helically coiled. An acrosome ispresent, composed of an apical vesicle and an acrosomal pedestal.The connecting piece or neck region is formed by a basal bodyplus a centriolar derivative. It is also the point of originof coarse fibres that accompany the axoneme. Thus, the axonemalcomplex exhibits a 9+9+2 pattern. The midpiece is an elongatedregion composed of paracrystalline and matrix materials (collectively,the mitochondrial derivative) enclosing a single glycogen helixand the axoneme. The mitochondrial derivative extends to theposterior tip of the spermatozoon. As observed in other stylommatophorans,both an annulus and a glycogen piece are absent. (Received 25 October 1993; accepted 4 February 1994)     

Comparative ultrastructure of ant spermatozoa (Formicidae: Hymenoptera)

Mature spermatozoa from spermathecae of founding queens were obtained from 5 species of ants, representing the major subfamilies Myrmicinae (Acromyrmex versicolor, Crematogaster sp.) and Dolichoderinae (Tapinoma sessile, Conomyrma insana, Conomyrma wheeleri). The ultrastructure of ant spermatozoa has many features in common with that of higher insects and is similar to that of other Hymenoptera. Structural similarities to spermatozoa of other Hymenoptera include an acrosome containing an internal rod that extends into the nucleus, two elongate mitochondrial derivatives, a centriolar adjunct, and an axonemal arrangement of 9 + 9 + 2 that includes well-developed coarse, or accessory, tubules. Spermatozoa obtained from A. versicolor, a species that is known to store and utilize viable sperm from this supply for over 10 years, show greater development of the mitochondrial derivatives than do the other species. The most distinctive feature of ant spermatozoa in comparison to other Hymenoptera is the large size of the centriolar adjunct relative to the other organelles. The centriolar adjunct is located posterior to the nucleus, anterior to the mitochondrial derivatives, and opposite the axoneme.     

Sperm structure and spermiogenesis in Coletinia sp. (Nicoletiidae, Zygentoma, Insecta) with a comparative analysis of sperm structure in Zygentoma

The spermatozoon of Coletinia sp. has a bilayered acrosome, a short nucleus (4 microm) and a relatively short sperm tail with two mitochondrial derivatives. The chromatin is uniformly dense except for several electron-lucid channels or strands which permeate the nucleus and which originate in the spermatid as invaginations of the nuclear envelope. The invaginations occur mostly or exclusively along two meridians of the spermatid that are also characterized by the presence of a longitudinal rod of medium electron density. The two rods (designated as 'mid-spermatid rods') evidently are instrumental in the formation of the electron-lucid channels. The significance of this elaborate system of intranuclear channels is not understood. The sperm tail has a 9 + 9 + 2 axoneme with each of the nine microtubular doublets accompanied by an accessory microtubule; scant intertubular material can also be distinguished. Hence, the tail axoneme resembles that of many pterygote insects. Each of the two mitochondrial derivatives contains a crystalline inclusion that has periodically spaced layers going in different directions on either side of the midline. Two synapomorphic traits appear to be shared by Ateluridae and Nicoletiidae, namely the invaginations of the nuclear membrane along two meridians of the nucleus and the shape of the crystalline inclusions of the mitochondrial derivatives. Four species from the family Lepismatidae were also examined as to their sperm ultrastructure. Three of them, Allacrotelsa kraepelini, Ctenolepisma longicaudata and Ctenolepisma sp., were found to be very similar to the two previously examined lepismatids, Thermobia domestica and Lepisma saccharina. On the other hand, spermatozoa of Tricholepisma aurea were aggregated in small groups rather than pairwise joined as seen in the other lepismatids. Sperm characters are also used to reconstruct a phylogenetic hypothesis which suggests a close relationship between Ateluridae and Nicoletiidae.     

Spermatozoa and sperm packages of the European troglophylous scorpion Belisarius xambeui Simon, 1879 (Troglotayosicidae, Scorpiones)

Studies on the sperm morphology in scorpions are rare, but the existing investigations already revealed a remarkable interfamiliar diversity. The present study reports for the first time on the spermatozoa and sperm packages of a representative of the family Troglotayosicidae, the troglophylous species Belisarius xambeui. The spermatozoa are characterized by (1) a thread-like nucleus, which is slightly bent anteriorly; (2) an asymmetrical cap-like acrosomal vacuole, which encloses the anterior tip of the nucleus; an acrosomal filament is absent; (3) an axoneme with a 9 + 0 microtubular pattern; (4) a midpiece consisting of elongated mitochondria coiling around the axoneme; the number can vary between 3 and 6 (mostly 4). At the end of spermiogenesis, the spermatozoa aggregate in order to form oval-shaped sperm packages in which all sperm cells show the same orientation. A single package consists of approximately 150 sperms. A secretion sheath is always absent. The present results might provide new characters for further systematic studies and their phylogenetic implications are briefly discussed.