Comparison of the oropharyngeal cavity in the Starksiini (Teleostei: Blenniiformes: Labrisomidae): Taste buds and teeth,including a comparison with closely‐related genera

The present study describes the distribution of taste buds and teeth in the oropharyngeal cavity of 13 species of adult (18–60 mm SL) Starksiini fishes inhabiting subtidal waters of the Neotropical region. Four types of taste buds described previously in other fish groups were observed within the oropharyngeal cavity, of which type I, situated on prominent protruding papillae, is the most common. The number of taste buds in this cavity varies considerably, ranging from ca. 202 in Starksia lepicoelia to ca. 770 in S. sluiteri. In all the studied species, taste buds are more numerous on the posterior (160–396) than on the anterior (42–294) part of the oropharyngeal cavity. The presence of different numbers of taste buds in different Starksiini species of the same standard length suggests that numbers of taste buds are not directly correlated with size and may be species‐specific. Teeth are found on the premaxilla, dentary, vomer, palatine (in some species) and the upper and lower pharyngeal jaws (third pharyngobranchials and fifth ceratobranchials, respectively); the form and number of teeth and taste buds on each of these sites differs among the various species of Starksiini and between them and closely related species of the labrisomid tribes Labrisomini, Mnierpini, and Paraclinini. The results thus suggest potential systematic value in certain features of the oropharyngeal cavity for blenniiform fishes. It is also shown that benthic‐feeding omnivorous fishes have higher densities of taste buds than piscivorous fishes. A possible correlation among numbers of taste buds, their positions in the oropharyngeal cavity, and other parameters is discussed. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

Reproductive histology of Tomeurus gracilis Eigenmann, 1909 (Teleostei: Atherinomorpha: Poeciliidae) with comments on evolution of viviparity in atherinomorph fishes

Tomeurus gracilis is a species long considered pivotal in understanding the evolution of livebearing in atherinomorph fishes. Tomeurus gracilis is a zygoparous or embryoparous poeciliid: internal fertilization is followed by females laying fertilized eggs singly or retaining fertilized eggs until or near hatching. Tomeurus was hypothesized as the sister group of the viviparous poeciliids until it was proposed as a close relative of a derived viviparous poeciliid, Cnesterodon, hence nested among viviparous taxa rather than near the root of the tree. Here, we describe and compare reproductive morphological characters of the little‐known Tomeurus with those of representative atherinomorphs. In Tomeurus and Cnesterodon, sperm are packaged in naked sperm bundles, or spermatozeugmata, in a configuration considered here diagnostic of viviparous poeciliids. Testes are single and free sperm are stored in the ovary in both taxa in contrast to oviparous atherinomorphs in which testes are paired and sperm are not packaged and not stored in the ovary. Efferent ducts in Cnesterodon testes and other viviparous poeciliids have a PAS‐positive secretion demonstrating presence of a glycoprotein that inactivates sperm or prevents final sperm maturation. No PAS‐positive staining secretion was observed in Tomeurus or oviparous atherinomorphs. Tomeurus shares apomorphic reproductive characters, such as sperm bundle and testis morphology and a gonopodium, with viviparous poeciliids and plesiomorphic characters, such as a thick zona pellucida with filaments, with oviparous taxa. We do not postulate loss or reversal of viviparity in Tomeurus, and we corroborate its phylogenetic position as sister to the viviparous poeciliids. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

草地螟雄蛾生殖系统的形态和结构

针对目前关于草地螟Loxostege sticticalis L.雄成虫生殖系统结构和功能的研究相对缺乏的状况,本文利用光镜和扫描电镜系统研究了草地螟雄蛾的内外生殖器官及相关结构。草地螟雄蛾内外生殖器官集中于腹部第5¹0腹节;内生殖器官位于510腹节;内生殖器官位于5⁸腹节内腔中,由睾丸(testes)、贮精囊(seminal vesicle)、输精管(vas deferens)、附腺(accessory gland)和射精管(ejaculatory ducts)组成;外生殖器官为腹部第9、10腹节的特化结构,包括抱握器(harpes)、背兜(tegumen)、基腹弧(vinculum)、钩形突(uncus)、颚形突(gnathos)、阳茎囊(aedeagal caecum)和阳茎(phallus)。外生殖器中抱握器的端刺(furcella)方向为雄蛾区别于其它种类的一个重要形态学特征。该研究首次明确了草地螟雄蛾的生殖系统结构,并为锥额野螟蛾属中种间分类提供更多的科学依据。     

Comparative morphology of the gonadal structure related to reproductive strategies in six species of neotropical catfishes (Teleostei: Siluriformes)

We studied the relationship between the morphology of the reproductive system and the reproductive strategies of six neotropical catfishes using macroscopic and microscopic analyses. The reproductive system of the examined Siluriformes showed diversified characteristics, but permitted their being grouped according to three reproductive strategies: pelagic spawning, demersal spawning, and internally fertilizing. The pelagic spawners Pseudoplatystoma corruscans and Conorhynchos conirostris have testes that are characterized by filiform lobes, absence of testicular secretion, full‐grown oocytes of small diameter, thin zona radiata, and cuboidal follicular cells. Pimelodus maculatus is morphologically distinct from the other two pelagic spawners catfishes due to the presence of testicular secretion. The demersal spawners Lophiosilurus alexandri and Rhinelepis aspera possess homogeneous testicular secretion, large mature oocytes, and columnar follicular cells. The most specialized reproductive system was observed in the internally fertilizing Trachelyopterus galeatus, which possesses a seminal vesicle accessory to the testes, spermatozoa with elongated nuclei that form spermatozeugmata, and a secretory ovarian lamellar epithelium that is associated with sperm storage. The reproductive system observed in Neotropical catfishes showed a relationship associated with the type of fertilization and the reproductive strategies of the six species studied. © 2011 Wiley‐Liss, Inc.     

Comparative morphology and cytology of the male sperm-transmission organs in viviparous species of clinid fishes (Clinidae: Teleostei, Perciformes)

This work comprises the first comparative study of the morphology and cytology of the sperm transmission organs in males of 14 species of viviparous clinid fishes (Clinidae, Blennioidei, Teleostei). The form and dimensions of these organs differ among the various species studied. The organs are composed of intra-abdominal ampullae, into which the sperm ducts and urinary bladder anchor, and an external protruding intromittent papilla used for insemination. The form of the ampullae differs among the various species, from pear-shaped to horseshoe-shaped. It increases in dimensions with increasing length of the male. In all the species this organ is covered by a connective-tissue tunic that encompasses both circular and longitudinal striated muscle bundles. The lumina of the ampullae harbor the epididymis, a strongly convoluted and plicated duct, which becomes filled with spermatozeugmata during reproduction. From here, the epididymis continues into the protruding intromittent papillae, where its folds gradually straighten at the apical part of the intromittent organ. The form and dimensions of this copulatory organ also differ in the various species. Papillae bearing taste buds are found on the apical parts of the intromittent organ, and it is probable that these, together with the difference in forms of the organ, help to prevent interspecific copulation.     

Gonadal morphology and difference in reproductive development of two isolated populations of Astyanax rivularis (Teleostei,Characidae)

Individuals of the same species may present different reproductive tactics depending on the environment in which they develop and mature. The present study aimed to define the gonadal development phases of males and females of Astyanax rivularis and to carry out a comparative analysis of the reproductive development of specimens captured in two isolated environments of the São Francisco River basin in Serra da Canastra, Brazil (Point 1: low vegetation and river showing calm and crystalline waters with small well formations; Point 2: current waters, and well-established areas of arboreal vegetation). Thus, the gonads of A. rivularis specimens were collected, fixed and processed with techniques for light microscopy. Five maturation phases of the females' reproductive cycle were established: immature, developing, spawning capable, regressing and regenerating. Three maturation phases of the males' reproductive cycle were observed: spawning capable, regressing, and regenerating. There are differences in the phases of gonadal development of A. rivularis between the two sampling points so that, possibly, animals upstream of the waterfall demonstrate a delay in the reproductive cycle in relation to animals downstream.     

泽兰实蝇内生殖器官的结构及其发育状况

【背景】泽兰实蝇属双翅目实蝇科,是杂草紫茎泽兰的重要专性天敌。该蝇幼虫可蛀入紫茎泽兰内部形成虫瘿,有效控制紫茎泽兰的扩散,许多国家都利用泽兰实蝇控制紫茎泽兰的危害。【方法】通过光学显微法观察了泽兰实蝇成虫内生殖器官的结构及其发育动态。【结果】雌性泽兰实蝇的内生殖系统主要由卵巢、输卵管、受精囊、雌性附腺等器官组成,雄性生殖系统由精巢、输精管、雄性附腺、射精管组成。在成虫发育过程中,雌虫卵巢的长度在第4日龄时达最大值,宽度在1日龄时达最大值,与其他日龄相比有显著差异,雌性附腺及受精囊的大小在各日龄间无显著差异;雄虫精巢长度在4日龄时达到最大,宽度在2日龄时达最大,且不同日龄间也有显著差异,而雄性附腺的大小在不同龄期间无显著差异。【结论与意义】本文阐明了泽兰实蝇的内生殖系统结构与发育状况,这有助于为提高泽兰实蝇人工繁殖效率及生物防治效果奠定理论基础。     

Morphology of the female reproductive organs of the African lion (Panthera leo)

The topography and splanchnology of the reproductive organs of the African lioness were studied and described in situ and after removal. The kidneys were located far caudally in relation to the thirteenth ribs. The suspensory ligament was very well developed, originated in a fan‐like manner from the dorsolateral abdominal wall lateral to the kidney and extended up to a few centimetres cranial to the kidney. The proper ligament of the ovary as well as the round ligament was well developed. The round ligament inserted on the medial femoral fascia. The left ovary was bigger than the right. The ovarian bursa had a short mesosalpinx that did not cover any part of the ovary and the fimbriae extended along the entire length. The urethral tuberculum as well as the urethral crest were well developed. The left uterine horn was longer than the right. The uterine tube was found to open directly into the tip of the uterine horn and not onto a papilla. The reproductive organs of the lioness resembled those of the domestic cat and dog but with some major differences.     

Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei,Aulopiformes, Synodontidae)

Fishelson, L., Golani, D., Russell, B., Galil, B. and Goren, M. 2012. Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei, Aulopiformes, Synodontidae). —Acta Zoologica (Stockholm) 93 : 308–318. This study compares the morphology and cytology of the alimentary tract in several species of lizardfishes (Synodontidae, Teleostei) of the genera Saurida, Synodus, and Trachinocephalus, in relation to their diets and bathymetric distribution. All the studied species feature a large, pouch‐like stomach, with the intestine beginning at the stomach’s anterior apex, adjacent to the esophageal opening. In the more ‘microphagous’Synodus spp. and Trachinocephalus, the intestine bends twice before reaching the anus, whereas in the more ‘macrophagous’Saurida spp., the intestine extends straight to the anus. The species differ also in the number and form of their pyloric ceca, the length of the intestine and in the percentile relationship between stomach length and standard body length. Along the alimentary tract folds and villi protrude into the lumen, their numbers differing on various sites of the tract. Three cell types make up the gastric gland system: (1) pyramidal cells forming the tubular gastric glands in the lamina propria; among them are large, pale secretary cells; (2) groups of neck cells that surround the pits of the tubules; and (3) groups of large and granule‐rich cells at the end portion of the stomach. All species are carnivorous and uniform in morphology, the differences in the alimentary tract found between the more shallow‐water species of Synodus and Trachinocephalus, and the deeper‐dwelling Saurida, seem to be only partly correlated with the differences in diet.     

Tempo of hybrid inviability in centrarchid fishes (Teleostei: Centrarchidae)

Hybrid viability decreases with divergence time, a pattern consistent with a so-called speciation clock. However, the actual rate at which this clock ticks is poorly known. Most speciation-clock studies have used genetic divergence as a proxy for time, adopting a molecular clock and often far-distant calibration points to convert genetic distances into age. Because molecular clock assumptions are violated for most genetic datasets and distant calibrations are of questionable utility, the actual rate at which reproductive isolation evolves may be substantially different than current estimates suggest. We provide a robust measure of the tempo at which hybrid viability declines with divergence time in a clade of freshwater fishes (Centrarchidae). This incompatibility clock is distinct from a speciation clock because speciation events in centrarchids appear to be driven largely by prezygotic isolation. Our analyses used divergence times estimated with penalized likelihood applied to a phylogeny derived from seven gene regions and calibrated with six centrarchid fossils. We found that hybrid embryo viability declined at mean rate of 3.13% per million years, slower than in most other taxa investigated to date. Despite measurement error in both molecular estimated ages and hatching success of hybrid crosses, divergence time explained between 73% and 90% of the variation in hybrid viability among nodes. This high correlation is consistent with the gradual accumulation of many genetic incompatibilities of small effect. Hybrid viability declined with the square of time, consistent with an increasing rate of accumulation of incompatibilities between divergent genomes (the snowball effect). However, the quadratic slope is due to a lag phase resulting from heterosis among young species pairs, a phenomenon rarely considered in predictions of hybrid fitness. Finally, we found that reciprocal crosses often show asymmetrical hybrid viabilities. We discuss several alternative explanations for this result including possible deleterious cytonuclear interactions. Speciation-clock studies have been a small cottage industry recently, but there are still novel insights to be gained from analyses of more taxonomic groups. However, between-group comparisons require more careful molecular-clock calibration than has been the norm.     

Phylogenetic systematics of the viviparous halfbeak genera Dermogenys and Nomorhamphus (Teleostei:Hemiramphidae:Zenarchopterinae)

Among the 13 genera and over 100 species of halfbeaks, three genera - Dermogenys, Nomorhamphus and Hemirhamphodon – are internally fertilized and viviparous. These genera belong to a more inclusive clade, the Zenarchopterinae, that also includes Zenarchopterus , inferred to be internally fertilized and to lay fertilized eggs, and the monotypic Tondanichthys , also inferred to be internally fertilized. Whereas the Hemiramphidae are distributed worldwide, internally fertilized halfbeaks are restricted to Southeast Asia. Recent data from histological surveys of the gonads of both males and females as well as embryonic modifications associated with viviparity have been combined here with osteological characters in a phylogenetic analysis. Results indicate overwhelming support for a sister-group relationship between Hemirhamphodon and {Dermogenys + Nomorhamphus). Monophyly of the Dermogenys + Nomorhamphus clade is also well supported. These results confirm earlier suggestions that Dermogenys , as previously defined, is paraphyletic. Within the Dermogenys + Nomorhamphus clade, two monophyletic clades are supported:one comprises ten species including four new species (Dermogenys bruneiensis, Dermogenys robertsi, Dermogenys palawanensis and Dermogenys collettei) and the other comprises 13 species including three undescribed species (Nomorhamphus rossi, Nomorhamphus pinnimaculata and Nomorhamphus manifesta). Diagnoses for the species of Dermogenys and Nomorhamphus , as well as a natural classification for the included species, are presented.     

Sexual dimorphism and reproductive behavior in the Brazilian scorpion Tityus pusillus (Scorpiones,Buthidae)

We studied sexual dimorphism (SD) and reproductive behavior in the litter‐dwelling scorpion, Tityus pusillus. SD was determined by measuring seven body structure attributes (prosoma, mesosoma, and metasoma lengths, and pedipalp chelae and metasomal segment V lengths and widths) in 634 individuals (211 males and 423 females) from the Arachnological Collection of the Universidade Federal de Pernambuco. Reproductive behavior was observed in 55 couples during nocturnal activity observations conducted in the laboratory. In addition, we evaluated gestation time, hemispermatophore replacement, and sequential courtship. Individuals of T. pusillus exhibited typical reproductive behavior, with a short courtship time (averaging 10±5 min). Males only accepted new partners at least 48 h after first mating, suggesting that this period may be necessary for hemispermatophore production. Females did not accept new partners for 24–48 h after their first mating. The average gestation period was 85±12 d, ranging 60–100 d. Our results showed a more complex picture of SD than previously described for this species, including features characteristic of both sexual size dimorphism (SSD) and sexual body component dimorphism in scorpions. In general, considering the relatively large size of the prosoma and mesosoma in T. pusillus, it seems reasonable to conclude that female‐biased SSD exists in the species, and that male‐biased sexual body component dimorphism is evident in the metasoma and chelae.     

琼花生殖器官结构及传粉昆虫的观察

为了探讨影响琼花Viburnum macrocephalum f.keteleeri有性生殖的因素,对其生殖生物学和传粉生物学进行了研究。研究内容主要包括琼花花部特征、生殖器官解剖结构、花粉活力、花粉胚珠比(P/O)、繁育系统、传粉形式、传粉昆虫和花粉管生长路径等。结果表明:(1)琼花聚伞花序由大型不孕花和小型可孕花组成,可孕花雌雄蕊发育正常,雄蕊5枚,雌蕊1枚,干型柱头,单子房,倒生胚珠;不孕花的雌雄蕊在发育早期正常,而在花期时退化。雄蕊退化表现为雄蕊消失、花丝缩短或消失或花药大小不一;而雌蕊退化表现为雌蕊缩小或柱头开裂;有时雌雄蕊也存在瓣化现象。(2)自然条件下,单花花粉活性在散粉4–5d后明显下降,居群花粉活力在4月25日–28日开始显著下降。(3)花粉胚珠比P/O值为12800–18700,属专性异交型;繁育系统为异株异花授粉,属虫媒传粉植物。(4)可孕花大量散粉时间为9:00–16:00,昆虫访花高峰时段为11:00–15:00,访花昆虫中以蝶类和蜂类为主,蝶类访花频率最高。(5)落置柱头的花粉萌发率较高,花粉粒授粉后1h左右开始萌发,花粉管从柱头乳突细胞的间隙穿入花柱,沿花柱中央引导组织生长,18h左右进入子房,20h左右从珠孔进入胚囊。讨论了琼花的不孕花形成、花部结构适应、花型演化趋势、低结实率和花粉管生长特点。     

Review Canalized pathways of change and constraints in the evolution of reproductive modes of microarthropods

This study investigates how the course of evolutionary change of an organismal pattern is canalized by organismal properties. As an example we use the mechanisms of indirect sperm transfer of some microarthropod groups. Miniaturized droplet spermatophores, characterized by a rather similar pattern of structural and functional components, are shown to have evolved independently in the Acari–Actinotrichida and the Pseudoscorpiones within the Arachnida and in the Entognatha (Collembola and Diplura–Campodeoidea), Symphyla, Pauropoda and Pselaphognatha within the Antennata. At least in the phylogenetic lineages leading to the various antennatan groups, evolution of miniaturized spermatophores took place in a similar sequence of transformation steps. It is likely that – originally – large sac spermatophores with a rigid sheath were deposited on the ground. The subsequent sequence of evolution involved carrying structures, a viscous sheath of the spermatophore-droplets, a stable water balance of the spermatophore under habitat conditions and miniaturized spermatophore droplets with immobilized sperm cells. Finally, mate dissociation became a common mode of behaviour in all groups mentioned. Each of the transformation steps was not only an adaptation to a particular selective condition, but additionally a precondition for further adaptive innovation. In this way the sequence of evolutionary change was rigidly determined. Moreover, integration of subsequently evolved components of the spermatophores into a complex network of interacting components obviously caused constraints of interaction, which in turn have caused a remarkable evolutionary stability of the character patterns. Using water mites as an example, it is shown how in a changed environment few behavioural changes have initiated an evolutionary sequence which has finally led convergently in several lineages to semi-direct or direct sperm transfer and to a massive repatterning of the original reproduction pattern. © Rapid Science Ltd. 1998     

南方山荷叶中甸居群繁殖生物学研究

对分布于云南中甸地区南方山荷叶进行的繁殖生物学研究结果表明 :南方山荷叶有性生殖良好 ,性成熟个体的花在开花前一年 7月末 8月初开始分化并以休眠芽的形式度过冬天及早春 ;花在次年春天开放并在植株露出地面 1 0 d之后进行传粉 ;每个体有花 3～ 2 8朵 ,每花有胚珠 1～ 1 7枚 ,每个体有胚珠 40～ 2 0 2枚 ;在自然条件下南方山荷叶传粉方式为异花授粉 (但自交可育 ) ,其传粉昆虫为叶蜂类和甲虫类 ;天然居群具有较高的结实率 ( 58.3%～1 0 0 .0 % ) ,每个体有果实 3～ 2 6枚 ,每果实有种子 0～ 1 1粒 ,平均结籽率为 60 .41 % ,每个体平均种子产量 47.0 5。南方山荷叶常可通过根状茎进行营养繁殖形成无性系植株。人工繁殖时既可用种子繁殖 ,亦可用切割根状茎来进行营养繁殖。     

Anatomy and ultrastructure of the reproductive organs in Dactylopodola typhle (Gastrotricha: Macrodasyida) and their possible functions in sperm transfer

Abstract. The reproductive anatomy of gastrotrichs is well known for several species, especially for the marine taxon Macrodasyida. However, there is little information on the reproductive organs and the modes of mating and sperm transfer in putative basal taxa, which is necessary for accurate reconstruction of the ground pattern of the Gastrotricha. We present the first detailed morphological investigation of the reproductive system of a putative basal gastrotrich, Dactylopodola typhle , using transmission and scanning electron microscopy, histology, and microscopic observations of living specimens. Dactylopodola typhle is a hermaphrodite that possesses paired female and male gonads, an unpaired uterus with an outlet channel that we call the cervix, and an additional accessory reproductive organ, the so-called caudal organ. We hypothesize that the hollow, secretory caudal organ serves for picking up autospermatozoa (self-sperm), for spermatophore formation, and finally for transferring the autospermatophore to a mating partner. The allospermatophore (foreign spermatophore) is stored within the uterus where fertilization occurs. We think that the mature and fertilized egg is released through the cervix and the dorsolateral female gonopore, and not by rupture of the body wall. Based on the morphology, we provide a plausible hypothesis for spermatophore formation and transfer in D. typhle . Preliminary phylogenetic considerations indicate that the stem species of Macrodasyida, perhaps that of all Gastrotricha, had paired ovaries and paired testes, an unpaired uterus, and only one accessory reproductive organ.     

Internal fertilization,testis and sperm morphology in glandulocaudinae fishes (Teleostei: Characidae: Glandulocaudinae)

In this report, the gonads of 32 glandulocaudine species, representing 18 genera, are compared with 11 outgroup characiform species. Through the presence of spermatozoa within the ovarian cavity, internal fertilization of the female is confirmed for the 16 genera for which mature ovaries were available. No outgroup ovary studied contains spermatozoa. All mature glandulocaudine testes have a large portion of the posterior testis, which is devoid of developing germ cells and spermatocysts (aspermatogenic), devoted to sperm storage, with the degree of partitioning in that region varying greatly within the group. All outgroup species examined have spermatozoa with spherical nuclei. With the exception of the species of the genus Planaltina, which also have spherical nuclei, all glandulocaudines have elongated nuclei, which vary among the species from 3.6 μm to 31.6 μm in length. Distinct sperm packets (spermatozeugmata) are formed in five genera by two different methods. In the genera Xenurobrycon, Tyttocharax, and Scopaeocharax, all of the tribe Xenurobryconini, the spermatozeugmata are formed within the spermatocysts and released fully formed. In all genera of the tribe Glandulocaudini, which includes Glandulocauda and Mimagoniates, loose spermatozoa are released which cluster into spermatozeugmata within the posterior storage areas. These morphological specializations are discussed within a phylogenetic framework as adaptations for internal fertilization and are hypothesized to be independently derived. © 1995 Wiley-Liss, Inc.