Morphology of the gas bladder in bumblebee catfishes (Siluriformes,Pseudopimelodidae)

The gross morphology of the gas bladder is described and compared for representatives of all valid genera of Pseudopimelodidae (Siluriformes). Cephalosilurus albomarginatus and species of Batrochoglanis, and Microglanis have the most basic form: a large, cordiform gas bladder with a simple internal T‐shaped septum. Cephalosilurus apurensis, C. fowleri, and C. nigricauda also have a large, cordiform gas bladder, but they have well‐developed trabeculae associated with the internal T‐shaped septum, and a pair of well‐developed constrictor muscles inserted on the external wall; the latter feature is present in most species of Pimelodidae, but absent in all other catfishes. The monotypic Lophiosilurus alexandri also has well‐developed constrictor muscles, and its gas bladder is moderately sized. The species of Pseudopimelodus and Cruciglanis have a diminutive gas bladder partially divided into two lateral sacs without internal communication, and lack constrictor muscles. The parapophysis of the fourth vertebra is a wide and long shelf connected to the dorsal surface of the gas bladder in most pseudopimelodid genera. However, in the species of Pseudopimelodus and Cruciglanis the parapophysis of the fourth vertebra is shorter and has its anterior ramus folded back, partially covering the gas bladder anteroventrally; and the tympanic opening is smaller than in species of the other genera. Five phylogenetic characters are proposed based on the morphology of the gas bladder and associated structures in species of Pseudopimelodidae, and the evolution of those characters in the family is discussed. J. Morphol., 2011. © 2011 Wiley‐Liss, Inc.     

Does the Hearing Sensitivity in Thorny Catfishes Depend on Swim Bladder Morphology?

Background

Thorny catfishes exhibit large variations in swim bladder morphology. These organs are of different sizes, forms and may have simple or branched diverticula. The swim bladder plays an important role in otophysans because it enhances their hearing sensitivity by transmitting sound pressure fluctuations via ossicles to the inner ear.

Methodology/Principal Findings

To investigate if a form-function relationship exists, the swim bladder morphology and hearing ability were analyzed in six species. The morphology was quantified by measuring the length, width and height and calculating a standardized swim bladder length (sSBL), which was then used to calculate the relative swim bladder length (rSBL). Hearing was measured using the auditory evoked potential (AEP) recording technique. Two species had simple apple-shaped and four species heart-shaped (cordiform) bladders. One of the latter species had short unbranched diverticula on the terminal margin, two had a secondary bladder and two had many long, branched diverticula. The rSBL differed significantly between most of the species. All species were able to detect frequencies between 70 Hz and 6 kHz, with lowest thresholds found between 0.5 and 1 kHz (60 dB re 1 µPa). Hearing curves were U-shaped except in Hemidoras morrisi in which it was ramp-like. Mean hearing thresholds of species possessing smaller rSBLs were slightly lower (maximum 8.5 dB) than those of species having larger rSBLs.

Conclusions/Significance

The current findings reveal a relationship between swim bladder form and its function among thorny catfishes. Relatively smaller swim bladders resulted in relatively better hearing. This is in contrast to a prior inter-familial study on catfishes in which species with large unpaired bladders possessed higher sensitivity at higher frequencies than species having tiny paired and encapsulated bladders.     

Homology of lungs and gas bladders: Insights from arterial vasculature

Gas bladders of ray‐finned fishes serve a variety of vital functions and are thus an important novelty of most living vertebrates. The gas bladder has long been regarded as an evolutionary modification of lungs. Critical evidence for this hypothesized homology is whether pulmonary arteries supply the gas bladder as well as the lungs. Pulmonary arteries, paired branches of the fourth efferent branchial arteries, deliver blood to the lungs in osteichthyans with functional lungs (lungfishes, tetrapods, and the ray‐finned polypterid fishes). The fact that pulmonary arteries also supply the respiratory gas bladder of Amia calva (bowfin) has been used to support the homology of lungs and gas bladders, collectively termed air‐filled organs (AO). However, the homology of pulmonary arteries in bowfin and lunged osteichthyans has been uncertain, given the apparent lack of pulmonary arteries in critical taxa. To re‐evaluate the homology of pulmonary arteries in bowfin and lunged osteichthyans, we studied, using micro‐CT technology, the arterial vasculature of Protopterus, Polypterus, Acipenser, Polyodon, Amia, and Lepisosteus, and analyzed these data using a phylogenetic approach. Our data reveal that Acipenser and Polyodon have paired posterior branches of the fourth efferent branchial arteries, which are thus similar in origin to pulmonary arteries. We hypothesize that these arteries are vestigial pulmonary arteries that have been coopted for new functions due to the dorsal shift of the AO and/or the loss of respiration in these taxa. Ancestral state reconstructions support pulmonary arteries as a synapomorphy of the Osteichthyes, provide the first concrete evidence for the retention of pulmonary arteries in Amia, and support thehomology of lungs and gas bladders due to a shared vascular supply. Finally, we use ancestral state reconstructions to show that arterial AO supplies from the celiacomesenteric artery or dorsal aorta appear to be convergent between teleosts and nonteleost actinopterygians. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

The gas bladder of puffers and porcupinefishes (Acanthomorpha: Tetraodontiformes): Phylogenetic interpretations

The anatomy of the gas bladder of Diodontidae (porcupinefishes) and Tetraodontidae (pufferfishes) was studied on the basis of dissections and magnetic resonance imaging. Among the examined taxa of Tetraodontiformes, only puffers and porcupinefishes possess a thick walled and dorsally U‐shaped or crescent‐moon‐shaped gas bladder. In the tetraodontid genus Lagocephalus the gas bladder is reduced to a rudiment. The species belonging to the genera Canthigaster, Arothron, and some species of Tetraodon differ in the positioning of their crescent‐moon‐shaped gas bladder. These observations confirm the close relationship of: (i) Diodontidae and Tetraodontidae and (ii) Canthigaster, Arothron, and some species of Tetraodon. The heterogeneity of the genus Tetraodon is supported by the gas bladder morphology, as previously suggested by molecular studies. J. Morphol. 275:894–901, 2014. © 2014 Wiley Periodicals, Inc.     

Stratified bacterial community in the bladder of the medicinal leech, Hirudo verbana

Most animals harbour symbiotic microorganisms inside their body, where intimate interactions occur between the partners. The medicinal leech, Hirudo verbana, possesses 17 pairs of excretory bladders that harbour a large number of intracellular and extracellular symbiotic bacteria. In this study, we characterized the bladder symbionts using molecular phylogenetic analyses, transmission electron microscopy (TEM) and fluorescence in situ hybridization (FISH). Restriction fragment length polymorphism (RFLP) and sequence analyses of 16S rRNA gene clone libraries suggested that six bacterial species co‐colonize the leech bladders. Phylogenetic analyses revealed that these species belong to the α‐Proteobacteria (Ochrobactrum symbiont), β‐Proteobacteria (Beta‐1 and Beta‐2 symbionts), δ‐Proteobacteria (Bdellovibrio symbiont) and Bacteroidetes (Niabella and Sphingobacterium symbionts). Species‐specific PCR detection and FISH confirmed the localization of the symbiotic bacteria in the bladders. The Ochrobactrum, Beta‐1, Bdellovibrio and Sphingobacterium symbionts were consistently detected in 13 leeches from two populations, while infection rate of the other symbionts ranged between 20% and 100% in the two leech populations. Transmission electron microscopy observations of the bladders revealed epithelial cells harbouring a number of intracellular bacilli and an additional type of extracellular, rod‐shaped bacteria in the luminal region. Fluorescence in situ hybridization with group‐specific oligonucleotide probes revealed the spatial organization of the bacterial species in the bladder: the Ochrobactrum symbiont was located intracellularly inside epithelial cells; the Bacteroidetes were localized close to the epithelium in the lumen of the bladder; and the Bacteroidetes layer was covered with dense β‐proteobacterial cells. These results clearly demonstrate that a simple but organized microbial community exists in the bladder of the medicinal leech.     

Changes in Nkx2.1, Sox2, Bmp4, and Bmp16 expression underlying the lung‐to‐gas bladder evolutionary transition in ray‐finned fishes

The key to understanding the evolutionary origin and modification of phenotypic traits is revealing the responsible underlying developmental genetic mechanisms. An important organismal trait of ray‐finned fishes is the gas bladder, an air‐filled organ that, in most fishes, functions for buoyancy control, and is homologous to the lungs of lobe‐finned fishes. The critical morphological difference between lungs and gas bladders, which otherwise share many characteristics, is the general direction of budding during development. Lungs bud ventrally and the gas bladder buds dorsally from the anterior foregut. We investigated the genetic underpinnings of this ventral‐to‐dorsal shift in budding direction by studying the expression patterns of known lung genes (Nkx2.1, Sox2, and Bmp4) during the development of lungs or gas bladder in three fishes: bichir, bowfin, and zebrafish. Nkx2.1 and Sox2 show reciprocal dorsoventral expression patterns during tetrapod lung development and are important regulators of lung budding; their expression during bichir lung development is conserved. Surprisingly, we find during gas bladder development, Nkx2.1 and Sox2 expression are inconsistent with the hypothesis that they regulate the direction of gas bladder budding. Bmp4 is expressed ventrally during lung development in bichir, akin to the pattern during mouse lung development. During gas bladder development, Bmp4 is not expressed. However, Bmp16, a paralogue of Bmp4, is expressed dorsally in the developing gas bladder of bowfin. Bmp16 is present in the known genomes of Actinopteri (ray‐finned fishes excluding bichir) but absent from mammalian genomes. We hypothesize that Bmp16 was recruited to regulate gas bladder development in the Actinopteri in place of Bmp4.     

A new species of Centromochlus (Siluriformes,Auchenipteridae, Centromochlinae) from the middle Rio Tocantins basin,Brazil

A new species of the catfish genus Centromochlus (Auchenipteridae, Centromochlinae) is described. The new species is diagnosed by having numerous dark rounded blotches over the body and fins, dorsal‐fin spine with serrations anteriorly and smooth posteriorly, anal fin of mature males with three unbranched and seven branched rays, anterior nuchal plate absent and posterior nuchal plate not extended ventrally. The new species is described from a small stream in the Estação Ecológica Serra Geral de Tocantins, a natural reserve in the centre of the Brazilian Cerrado, close to the watershed between the Rio Tocantins and the Rio São Francisco basins. The new species is possibly the sister taxon to the recently described Centromochlus meridionalis from the upper Rio Tapajós. Those two species share with Centromochlus perugiae, from the upper Amazon and upper Paraguay, derived features associated with the modified anal fin in sexually mature males.     

Regeneration of posterior segments and terminal structures in the bearded fireworm,Hermodice carunculata (Annelida: Amphinomidae)

Like many other annelids, bearded fireworms, Hermodice carunculata, are capable of regenerating posterior body segments and terminal structures lost to amputation. Although previous research has examined anterior regeneration in other fireworm species, posterior regenerative ability in fireworms remains poorly studied. As the morphology of the anal lobe (a small, fleshy terminal structure of unknown function) has been used to distinguish East and West Atlantic H. carunculata populations, there is a more imminent need to understand the morphology and organization of tissues in specimens undergoing posterior regeneration, and the timeframe in which significant developmental changes occur. To further investigate this phenomenon, we amputated the posterior segments of living H. carunculata specimens collected from the Gulf of Mexico and monitored posterior regeneration over a 6‐month study period. Although many aspects of posterior regeneration in H. carunculata are consistent with the findings of other annelid regeneration studies, histological analysis revealed that once formed, anal lobe morphology remains relatively unchanged at all stages of posterior regeneration; East Atlantic morphotypes were not observed in the West Atlantic specimens studied here. Additionally, we found that the ventral nerve chord, which is partially responsible for the regeneration of lost body parts in polychaete annelids, terminates within the anal lobe, suggesting that this structure may play a role in the formation of new segments. J. Morphol. 275:1103–1112, 2014. © 2014 Wiley Periodicals, Inc.     

Seed formation in two species of Adesmia (Fabaceae): co‐occurrence of micropylar and lateral endosperm haustoria in legumes and its taxonomic value

Seed ontogeny of Adesmia bicolor and Adesmia latifolia was analysed using light microscopy and standard histological techniques. Fertilization was porogamic. Linear proembryonal tetrads were observed in A. bicolor. The robust elongated suspensors possessed specialized basal cells. The nucellar epidermis became endothelial. The free‐nuclear endosperm produced a micropylar, filamentous and ephemeral haustorium and a lateral sac‐like haustorium at the funicular side. The cellular endosperm was initiated from the micropylar zone after the cordiform embryo stage. It mostly disintegrated in mature seeds. The sclerified bilayered testa was derived from the outer ovular integument. Different astrosclereid arrangements beyond the lens in both Adesmia species may be related to the different habitats of the two species. The occurrence of both micropylar and lateral nuclear endosperm haustoria has so far not been reported in Fabaceae and is the most distinctive embryological character of Adesmieae. The taxonomic value of the mostly uniform morphology of the suspensor in the Adesmia species studied could also be relevant. The nature of seed endothelia in many Fabaceae requires accurate redetermination prior to taxonomic use. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 602–612.     

Distribution and Relative Size of the Swim Bladder in Percina, With Comparisons to Etheostoma, Crystallaria, and Ammocrypta (Teleostei: Percidae)

The distribution of the swim bladder was examined in 20 species representing all four genera (Percina, Etheostoma, Crystallaria, and Ammocrypta) of darters (Etheostomatini). Including data on species examined in other studies, swim bladders have been found in 15 of 17 species of Percina, but were absent in Crystallaria asprella, Ammocrypta pellucida, and the 18 species of Etheostoma examined. Relative swim bladder length in Percina was shown to be positively correlated with body size. Although not statistically significant, swim bladder size also correlates with habitat (riffle, run, or pool) and swimming behavior (midwater or benthic).     

Warneckea cordiformis sp. nov. (Melastomataceae–Olisbeoideae) from a coastal dry forest in northern Mozambique

Described and illustrated is Warneckea cordiformis R. D. Stone, an evidently localized endemic of coastal dry forest in Mozambique's Cabo Delgado Province. In ‘Flora Zambesiaca’ the new species would key to W. sansibarica (Taub.) Jacq.‐Fél., from which it is readily distinguished by the much smaller, ovate to cordiform leaves and white, short‐pedicellate flowers. Because of its evidently very limited occurrence as well as on‐going anthropogenic threats, Warneckea cordiformis is here assessed as ‘Critically Endangered’ (CR) B1a,b(iii) according to IUCN criteria. A key is provided to the Mozambican species of Warneckea.     

Morphological development of the swim bladder in hatchery-reared striped trumpeter Latris lineata

This study examined swim bladder morphogenesis in three cohorts of striped trumpeter (Latris lineata), a euphysoclist species with physostomous larvae. The swim bladder was first discernible 1–2 days after hatching as an evagination on the dorsal surface of the incipient digestive tract. It comprised a cluster of mesenchymal cells surrounding an inner primordium of epithelial cells. At mouth opening in larvae of 5.3 mm standard length (SL), the swim bladder was noticeably enlarged. Histologically, the swim bladder lumen was dilated and liquid filled. The pneumatic duct was first seen during the dilation stage and the rete mirabile began forming among the connective tissue surrounding the swim bladder. Initial swim bladder inflation occurred on day 11 post‐hatching in Cohort 1, at 14°C, and day 9 post‐hatching, in Cohorts 2 and 3, at 16°C. Histologically, the lumens of inflated swim bladders were ellipsoid and the epithelium was squamous, except for cuboidal gas gland cells at the anterio‐ventral and anterio‐lateral regions of the swim bladder. During the initial inflation interval the pneumatic duct was dilated in larvae both with and without swim bladder inflation. The pneumatic duct began to regress in some larvae over 7.5 mm SL. The swim bladder of striped trumpeter was similar to larvae of other altricial perciform marine fish in respect to organ derivation, tissue differentiation, luminal dilation and initial gaseous inflation. However, variations, particularly the delay in initial swim bladder inflation until after the start of feeding, were observed that could be fundamental to problems encountered during larval rearing.     

Gonad morphology,oocyte development and spawning cycle of the calanoid copepod <Emphasis Type="Italic">Acartia clausi</Emphasis>

Information on gonad morphology and its relation to basic reproductive parameters such as clutch size and spawning frequency is lacking for Acartia clausi, a dominant calanoid copepod of the North Sea. To fill this gap, females of this species were sampled at Helgoland Roads from mid March to late May 2001. Gonad structure and oogenesis were studied using a combination of histology and whole-body-analysis. In addition, clutch size and spawning frequency were determined in incubation experiments, during which individual females were monitored at short intervals for 8 and 12 h, respectively. The histological analysis revealed that the ovary of A. clausi is w-shaped with two distinct tips pointing posteriorly. It is slightly different from that of other Acartia species and of other copepod taxa. From the ovary, two anterior diverticula extend into the head region, and two posterior diverticula extend to the genital opening in the abdomen. Developing oocytes change in shape and size, and in the appearance of the nucleus and the ooplasm. Based on these morphological characteristics, different oocyte development stages (OS) were identified. Mitotically dividing oogonia and young oocytes (OS 0) were restricted to the ovary, whereas vitellogenic oocytes (OS 1–4) were present in the diverticula. The development stage of the oocytes increased with distance to the ovary in both, anterior and posterior diverticula. Most advanced oocytes were situated ventrally, and their number varied between 1 and 18, at a median of 4. All oocyte development stages co-occur indicating that oogenesis in A. clausi is a continuous process. These morphological features reflect the reproductive traits of this species. In accordance with the low numbers of mature oocytes in the gonads, females usually produced small clutches of one to five eggs. Clutches were released throughout the entire observation period at intervals of 90 min (median) resulting in mean egg production rates of 18–28 eggs female⁻¹ day⁻¹.     

Predation by the tropical plant Utricularia foliosa

1. We examined the prey captured by individual plants of the tropical carnivorous plant Utricularia foliosa, located in different areas along a creek in the Colombian Amazon and the zooplankton and macroinvertebrate communities associated with the plants. The aims were: (i) to determine whether bladders of different sizes within each plant catch different numbers of prey or exploit different size ranges and types of prey, (ii) if the quantity and composition of prey captured varies temporally and/or spatially and (iii) if the plant has evolved effective mechanisms of attracting prey. 2. Utricularia foliosa captured the most abundant species of macroinvertebrates associated with the plant. Larger bladders captured more, larger and more diverse prey. However, benefits of the extra prey caught by large bladders were not offset by the greater cost of producing bladders larger than approximately 1650 μm. 3. The number of prey captured was higher in those plants with more carbohydrates per bladder and with a higher ratio of antenna size/bladder length. The antennae enhance capture success by offering the prey a favourable substratum that exploits their natural locomotor and feeding behaviour. However, although carbohydrates may lure prey, carbohydrate production was not a strategy of the plant to enhance the capture of prey, because the amount of carbohydrates in the bladder was related to the abundance of periphyton.     

Description of a new species of Triplophysa (Teleostei: Nemacheilidae) from Guizhou Province,China

A new cave‐dwelling fish species Triplophysa guizhouensis is described based on specimens collected from Guizhou, China, in a subterranean system interconnected with the Hongshui River drainage. The species can be distinguished from its congeners by a combination of characters: eyes present; caudal fin with 14 branched rays; inner gill rakers of first gill arch 8–10; posterior chamber of air bladder developed; and body posterior of dorsal fin scaled. A key to species of Triplophysa in the Pearl River basin is provided.     

Monthly changes in the swim bladder morphology of the female Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis> in the coastal waters of Mikawa Bay,Japan

In the coastal area of Mikawa Bay, central Japan, specimens of the female Japanese eel Anguilla japonica could be divided into two groups according to the degree of swim bladder development. In one case, they were undeveloped, and in the other, they were highly developed with large rete mirabile, thick submucosa, and a well-developed gas gland. The morphology of the swim bladder in the latter group was comparable with that in the artificially fully maturated eel. The specimens with an undeveloped swim bladder were caught during all months, although their number was small. The specimens with a highly developed swim bladder were most abundant in November and December. During these months, catch of the specimens also increased sharply, by more than 10 fold compared to that in other months. These observations indicate that most of the eel appearing in coastal Mikawa Bay from October to January have a highly developed swim bladder adapted for a deep-sea environment. It was also conjectured that these specimens most likely migrated from rivers feeding into Mikawa Bay, toward spawning grounds in the open sea, and that this occurred after development of their swim bladders was completed. Actually, the specimens caught in the upstream of the Toyo River feeding into Mikawa Bay from late August to early October already had highly developed swim bladders.     

Male and female genitalia in some Libyan species of Acrididae (Orthoptera: Acridoidea)

A comparative study of male and female genitalia was carried out in thirty‐seven Libyan species representing twenty genera of the family Acrididae. An attempt has been made to describe and illustrate the different structures, namely, epiphallus, aedeagus, subgenital plate, supra‐anal plate and cerci of the male, and spermatheca, ovipositor, subgenital plate, supra‐anal plate and cerci of the female, in Acridids, with an aim to discover their significance in order to make the identification of genera and species, together with other generic characters, more perfect and convenient. Distinct family characters are shield or bridge‐shaped condition of epiphallus; presence or absence of dorso‐lateral appendices, oval sclerites and lophi on epiphallus; divided, undivided or flexured condition of aedeagus; presence or absence of gonopore process on aedeagus; condition of apical and pre‐apical diverticula of spermatheca; presence or absence of glandular pouches of Cornstock and Kellog on female subgenital plate; and rudimentary or well developed condition of egg‐guide. Stable characters for separating the subfamilies are taken to be presence or absence of ancorae on epiphallus, long or short condition of aedeagal sclerites; elongate, slender or short and broad condition of ovipositor valves: presence or absence of Jannone's organs and setae on posterior margin of female subgenital plate; and shape of diverticula of spermatheca. Useful generic characters are shape of male subgenital plate, supra‐anal plate and cerci, broad or narrow condition of bridge, presence or absence of branch of bridge connecting lophi with bridge of epiphallus; mono‐, bi‐ or tri‐lobate condition of lophi of epiphallus, length and upcurved or downcurved condition of apical valve of aedeagus, shape of posterior margin of female subgenital plate, presence of setae on the whole posterior margin or confined to lateral margins only; and toothed, tuberculate or smooth condition of ovipositor valves, length of the lateral apodeme in relation to the dorsal valves. Specific characters are shape of egg‐guide of female subgenital plate, shape of ovipositor valves and apical tips, shape of male supra‐anal plate and cerci, size of anterior and posterior lobes of lophi of epiphallus, size and shape of ancorae, shape of apical valves of aedeagus; and size of apical and pre‐apical diverticula and presence of protuberance on pre‐apical diverticulum.     

A correlative study of the allantois in pig and rabbit highlighting the diversity of extraembryonic tissues in four mammalian species,including mouse and man

Despite its conserved role in placenta and umbilical cord formation, the mammalian allantois shows remarkable diversity in size and form as well as in the timing of its appearance and attachment to the chorion. In the mouse, the common allantoic diverticulum is lacking; instead, the allantoic core domain is defined as a progenitor center for allantoic development. In this study, the allantoises of the pig and the rabbit as two nonrodent mammals of increasing significance in biomedical research are compared (1) morphologically using high resolution light and electron microscopy and (2) molecularly using brachyury mRNA expression as a mesodermal marker. Multiple small allantoic diverticula in the rabbit contrast with a single large cavity filling the entire allantois of the pig, but neither pig nor rabbit allantois expresses brachyury . The mesothelium on the allantois surface shows regional variability of cell contacts and microvilli, while blood vessels appear randomly around the allantoic diverticula in a mesodermal layer of variable thickness. Primordial germ cell‐like cells are found in the allantois of the pig but not of the rabbit. To understand further the relevance of this developmental and morphological diversity, we compare the allantois development of pig and rabbit with early developmental landmarks of mouse and man. Our findings suggest that (1) tissue interaction between endoderm and mesoderm is important for allantoic development and vascular differentiation in species with a rudimentary allantoic diverticulum, (2) allantoic mesothelium plays a specific role in chorioallantoic attachment, allantoic differentiation and vascularization, and (3) there is a pronounced diversity in the extraembryonic migratory pathways of primordial germ cells among mammals. Finally, the phylogenetically basal characteristics of the pig allantois are suggestive of a functional similarity in mammals with a large allantois before placentation and in (aplacental) sauropsids with a chorioallantoic membrane well‐adjusted to material exchange function.