Scanning Electron Microscopy of the Adoral Ciliary Zone of Entodinium Stein (Ciliophora,Entodiniomorphida)1

The adoral ciliary zone of the rumen ciliates, Entodinium spp., was observed topographically in the SEM. The upper side of the anterior end of the body was indented by the vestibulum, which had cilia arranged on its right wall and ribs along the left wall. The adoral ciliary zone could be divided into at least two arrangements. The outer ciliary zone had many membranelle-like structures, which consisted of cilia arranged radially from the body axis. Each membranelle-like structure consisted of two rows of about eight cilia each lining up in a single file. It was, however, different from a typical membranelle, because its cilia were connected with the vestibular cilia and were arranged not spirally but on a plane. These cilia extended toward the outside because of the projecting cytoplasm from which they originated. In contrast, the cilia of the inner ciliary zone were aggregated to form relatively unsystematic bundles. Since the vestibular opening was slanted on the upper side of the body, the ciliary bundles were thick on the lower side and sparse on the upper side of the body. Neither outer nor inner ciliary zones completely surrounded the vestibular opening. The ciliature started from the left side of the vestibular opening, encircled the lower side of the body, and entered the vestibulum from its right side. The functions of these two types of ciliary arrangements are discussed.     

FEEDING APPARATUS OF THE COLORLESS FLAGELLATE KATABLEPHARIS (CRYPTOPHYCEAE)1

The feeding apparatus of Kalablepharis ovalis (isolated from a freshwater impoundment in Colorado) and Katablepharis clone G-2 (isolated from the littoral of the Black Sea near Yalta in the Crimea) consists of inner and outer oval-shaped arrays of microtubules that begin at the anterior end of the cell and pass into the posterior of the cell. Each array of microtubules contains groups of microtubules with two to eight microtubules per group depending on the position of the array in the cell. A specialized area of the plasma membrane, the mouth, occurs at the anterior end of the cell. The mouth is oval with the long axis oriented dorsoventrally and consists of a raised ridge surrounding a central depression. The anterior end of the microtubules of the inner and outer arrays supports the raised ridge of the mouth. In freeze-fracture replicas, the protoplasmic face of the plasma membrane contains intramembrane particles on the raised ridge of the mouth. Three small membrane-cisternae occur on the protoplasmic side of the plasma membrane in the area of the mouth. Katablepharis clone G-2 also has five or six additional large membrane-cisternae associated with the inner microtubular array in the anterior portion of the cell. These larger membrane-cisternae do not occur in K. ovalis. Vesicles with electron-dense contents occur in association with the microtubular arrays. Katablepharis ovalis has a second type of vesicle containing a single-membrane profile associated with the microtubule arrays. The structure of the microtubular arrays in Katablepharis is compared with similar structures in suctorian ciliates and dinoflagellates.     

Temperature-dependent stomatal movement in tulip petals controls water transpiration during flower opening and closing

Temperature‐dependent tulip petal opening and closing movement was previously suggested to be regulated by reversible phosphorylation of a plasma membrane aquaporin ( Azad et al., 2004a ). Stomatal apertures of petals were investigated during petal opening at 20°C and closing at 5°C. In completely open petals, the proportion of open stomata in outer and inner surfaces of the same petal was 27 ± 6% and 65 ± 3%, respectively. During the course of petal closing, stomatal apertures in both surfaces reversed, and in completely closed petals, the proportion of open stomata in outer and inner surfaces of the same petal was 74 ± 3% and 29 ± 6%, respectively, indicating an inverse relationship between stomatal aperture in outer and inner surfaces of the petal during petal opening and closing. Both petal opening and stomatal closure in the outer surface of the petal was inhibited by a Ca²⁺ channel blocker and a Ca²⁺ chelator, whereas the inner surface stomata remained unaffected. On the other hand, sodium nitroprusside, a nitric oxide donor, had no effect on stomatal aperture of the outer surface but influenced the inner surface stomatal aperture during petal opening and closing, suggesting different signalling pathways for regulation of temperature‐dependent stomatal changes in the two surfaces of tulip petals. Stomata were found to be differentially distributed in the bottom, middle and upper parts of tulip petals. During petal closing, water transpiration was observed by measuring the loss of ³H₂O. Transpiration of ³H₂O by petals was fivefold greater in the first 10 min than that found after 30 min, and the transpiration rate was shown to be associated with stomatal distribution and aperture. Thus, the stomata of outer and inner surfaces of the petal are involved in the accumulation and transpiration of water during petal opening.     

Structure and morphogenesis of the eggshell and micropylar apparatus in the olive fly, Dacus oleae (Diptera: Tephritidae)

The egg of the olive fly, Dacus oleae (Diptera, Tephritidae), is laid inside olives and the larva eventually destroys the fruit. The oocyte is surrounded by several distinct layers which are produced during choriogenesis. The chorion covering the main body of the egg outside of the vitelline membrane includes a "wax" layer, an innermost chorionic layer, an endochorion consisting of inner and outer layers separated by pillars and cavities similar to their counterparts in Drosophila melanogaster, as well as inner and outer exochorionic layers. The anterior pole is shaped like an inverted cup, which is chiefly hollow around its base and has very large openings communicating with the environment. Holes through the surface of the endochorion result from deposition of endochorionic substance around follicular cell microvilli. An opening at the apex of the cup provides an entrance for sperm entering the micropylar canal, which traverses the endochorion and continues into a "pocket" in a thickened vitelline protrusion. The micropylar canal is formed by deposition of endochorion and vitelline membrane around an elongated pair of follicular cell extensions. These extensions later degenerate and leave an empty canal about 5 microns in diameter and the narrower pocket about 1 micron in diameter. Respiration is thought to be facilitated by openings at the base of the anterior pole as well as by openings through the "plastron" around the main body of the shell.     

Setal Structure and Chaetogenesis in Scolelepis squamata and Malacoceros fuliginosus (Spionidae,Annelida)

In Scolelepis squamata and Malacoceros fuliginosus two alternatingly arranged transverse rows of setae are found in each ramus. These are capillary setae in all thoracic setigers, whereas in abdominal setigers they may alternate with hooded hooks. In M. fuliginosus only the abdominal neuropodia bear hooded hooks, whereas in S. squamata these setae are present in both rami in the abdomen. Here every second seta (the capillary one) degenerates before its formation is complete, leading to a single row of hooded hooks. In the transverse rows new setae are formed in a medio-lateral formative site in both species. Additionally in each ramus there exists one longitudinal row of capillaries which each possesses its own formative site. Ultrastructure and formation of the hooded hooks in S. squamata is very similar to that of hooded hooks in Capitellidae. The hood is preformed by a certain group of microvilli of the chaetoblast, which soon differentiates two layers of microvilli, raising an inner and an outer hood lamella. The hooded hooks and their arrangement are regarded as homologous characters in Spionidae and Capitellidae. This indicates a closer relationship of Spionidae with a taxon consisting of Capitellidae, Arenicolidae, Maldanidae, Oweniida, Terebellida, Sabellida, and Pogonophora.     

A new species of the genus <Emphasis Type="Italic">Balitora</Emphasis> (Teleostei: Balitoridae) from Guangxi,China

A new species of the hillstream loach genus Balitora Gray, Balitora ludongensis, from Qilong River which drains to Zuojiang River (a headwater of the Pearl River) drainage, Jingxi County, Guangxi, China. It can be distinguished from its congeners by the following characters: pectoral fin with vi–vii, 11–12 rays; pelvic fin with ii, 6–7 rays; pre-oral groove relatively shallow, upper lip without or with 3–5 fold-like papillae in a row on its middle surface and gradually smooth to the corner of mouth; two maxillary barbels at each corner of mouth, the outer one slightly longer than the inner one, 149.0–190.9% of eye diameter; eyes small, eye diameter 14.2–18.1% of head length; Dorsal-fin origin slightly anterior to pelvic-fin origin; Caudal-peduncle depth 39.1–55.0% of its length; upper lobe of caudal fin longer than the lower one; lateral-line scales 69–74; with 6–9 black blotches on the dorsal side of body.     

The architecture of the anterior appendage in the egg of the assassin bug, Zelus longipes (Hemiptera: Reduviidae)

The eggshell of Zelus longipes, a Hemiptera species of the family Reduviidae (assassin bugs), has been studied using Scanning Electron Microscopy (SEM). The emphasis was on the architecture of an anterior appendage connected to the main eggshell of both ovarian and deposited eggs. The analysis of eggs fractured at various angles and levels reveals a relatively complex organization of this appendage. There is a cylindrical outer layer, the veil, of roughly the same diameter as, and continuous with, the main eggshell. At its anterior pole, the veil folds inwards and forms an hourglass-shaped tube that is attached through slender extensions to a curved plate oriented at right angles to the long axis of the egg and spanning the internal diameter of the veil. The plate is solid at the center, shows honeycomb-shaped perforations in its mid-section and contains a very delicate meshwork along its circumference. Underneath the plate lies a hollow cylinder oriented at right angles to the long axis of the egg and attached to the anterior plate of the egg, the operculum. The outer openings of aeropyles lie at the inner face of the veil and at its base. While the outer surface of the entire eggshell appears smooth, the inner face of the anterior appendage is highly and diversely sculptured. The eggs are deposited in batches of at least 15 and completely surrounded by viscous secretion. This substance does not encroach on the anterior appendage. The major function of this appendage may lie in the protection of the aeropyles and particularly in preventing their being clogged by the viscous material.     

Unique patterns of longitudinal body-wall musculature in the Acoela (Plathelminthes): the ventral musculature of Convolutriloba longifissura

The ventral musculature of Convolutriloba longifissura (Acoela) has been studied using electron microscopy and fluorescently labeled whole mounts to demonstrate filamentous actin. Attention was directed to the reorganization and renewal of musculature during asexual reproduction and the adaptation of muscle sets for special predatory behavior. Three ventral subepidermal muscle layers could be distinguished in adult C. longifissura: (1) outer circular muscles that encircle the body, (2) intermediate modified longitudinal muscles with concentric pattern around the mouth and V-shaped orientation in the posterior part of the animal, and (3) inner special pore muscles with radial alignment fanning out from the mouth. Additionally, a few very fragile muscles were found at the anterior margin of the animal. The anterior ventral muscle system built a funnel with the mouth opening as organizing center. The special radial muscles and the antagonistically concentric muscles are perfectly adapted to catch prey in such a way that the funnel is put over the prey to press it through the mouth into the digestive syncytium. Convolutriloba longifissura shows a unique way of asexual reproduction by a two-step fission which results in three individuals. Immediately after separation from the mother animal, daughter individuals are missing the concentric and the radial muscle sets around the mouth completely, but within 30 h these sets are renewed for the most part. Two to three days after separation, the mouth opening is visible and the animals move for capturing prey. The peculiar course of longitudinal muscles in C. longifissura with concentric rings anteriorly and a V-shape muscle layer posteriorly shows that the pattern of body-wall musculature in such basal Plathelminthes as the Acoela may be highly modified from the original pattern of longitudinal and circular muscles.     

Cystacanths of Acanthocephala in notothenioid fish from the Beagle Channel (sub-Antarctica)

The morphology of relaxed cystacanths of polymorphid acanthocephalans collected from notothenioid fishes in the Beagle Channel (Magellanic subregion of sub-Antarctica) is described. A parasite of birds, Andracantha baylisi (Zdzitowiecki, 1986), was found in Patagonotothen longipes and Champsocephalus esox. It has: a proboscis 0.82–0.89 mm long; a proboscis hook formula of 16 rows of 9/10–10/11, including 4–5 basal hooks; distal hooks with the longest blades; a fore-trunk not separated from the hind-trunk by a constriction; large somatic spines arranged in two zones separated by a zone of small, loosely dispersed spines; and only the anterior 36–40% of ventral side of the trunk is covered with spines. One male specimen of Corynosoma sp. was found in Patagonotothen tessellata. It differs from A. baylisi in that the distal proboscis hooks are similar in length to the prebasal hooks, it has a smaller proboscis (0.77 mm) and in the distribution of the somatic spines, which are contiguous with the genital spines on the ventral side of the trunk and lack a zone of small spines between zones of larger spines. A parasite of seals and fur seals, Corynosoma evae Zdzitowiecki, 1984, was found in P. longipes and Champsocephalus esox. It has: a proboscis 0.61–0.78 mm long; a proboscis hook formula of 20–22 rows of 12–13, including 3/4–4 basal hooks; prebasal hooks with the longest blades; a trunk divided into fore-trunk and hind-trunk; somatic spines covering the anterior 64–74% of the ventral side of the trunk; genital spines present only in males; and a terminal genital opening in both sexes. Corynosoma beaglense n. sp. was found in Champsocephalus esox. It has: an almost cylindrical proboscis (length 0.52–0.56 mm); a proboscis hook formula of 16 rows of 9/10–10/11, including 4–4/5 basal hooks; distal hooks shorter than the prebasal hooks; a fore-trunk not separated from the hind-trunk by a constriction; somatic spines contiguous with the genital spines on the ventral side of the trunk of the male and covering the entire length of the ventral side of the female trunk, and the presence of genital spines surrounding the terminal genital pore of the male. The definitive host of this species is unknown.     

Scanning Electron Microscopy of the Adoral Ciliary Zone of Cycloposthium Bundle (Ciliophora,Entodiniomorphida)1

The adoral ciliary zone of Cycloposthium spp., inhabiting the large intestine of the horse, was studied by scanning electron microscopy. It could be divided into four parts: outer, inner, left, and right zones. The outer zone, extending on the anterior periphery of the apical cone of the body, had 20 tuft-like syncilia arranged radially around the longitudinal axis. Each ciliary tuft consisted of about 170 cilia, and in cross section it had a rectangular shape. The cilia of the inner zone, situated at the top of the apical cone, were aggregated irregularly to form shorter bundles than the tufts of the outer zone. The innermost cilia of this zone were shorter than the outermost. There was a distinct non-ciliated border between the outer and inner zones. A horseshoe-like operculum having no cilia was present at the center of the adoral ciliary zone, and the opening of the vestibulum was situated as a cleft crossing from the center to the right periphery of this zone. No cilia extended onto the vestibular wall. The left ciliary zone was situated beneath the outer zone and consisted of five short rows of barren kinetosomes of which only the central row possessed very short cilia. The right ciliary zone, consisting of a few rows of cilia situated at the bottom of the inner adoral lip, was also easily distinguished from the other ciliary zones. This zone was interpreted as an extension of the outer adoral zone passing along the right side of the apical cone. These ciliary zones were considered to be highly differentiated and useful for both movement of and ingestion of food.     

Microtopography of Nippostrongylus brasiliensis (Nematoda: Heligmosomatidae): Free-living larval stages

Microtopographic features of the various growth stages of the three free-living larval stages of the rat hookworm Nippostrongylus brasiliensis (Nematoda) were surveyed by scanning electron microscopy. These worms have a rounded anterior end and an elongated tail. Cuticular annulations were observed along the body, which also bore two ribbon-like lateral alae. Two rings of six lip-like lappets were observed around the triradiate oral opening in all larval stages. The cephalic space contained two lateral amphidial pits. The excretory pore in the third anterior part was observed in a ventral view of the larvae. No deirids were observed. The anus with a crescent-shape opening was located posteriorly. Phasmidial apertures, only observed in the third-stage larvae, opened on the lateral alae in the tail region. © 1993 Wiley-Liss, Inc.     

Ultrastructure and formation of hooded hooks in Capitella capitata (Annelida, Capitellida)

 The hooded hooks of Capitella capitata are aligned in a transverse row inside each neuro- and notopodial rim of the last thoracic and all abdominal setigers. Each seta consists of a rostrum, a capitium, the spines of which surmount the rostrum, and a long, sigmoid shaft or manubrium, towards which rostrum and capitial spines are curved. A thin hood, complete except for a subapical opening and a short, subrostral cleft, encloses the apical portions of the seta. Generally, the tip of the rostrum extends beyond the hood. The hood consists of an outer and an inner lamella, between which is a compartment loosely filled with fibrillar material. Hooded hooks are generated at the dorsal edge of the neuropodial rim and at the ventral edge of the notopodial rim during the entire life of C. capitata. Chaetogenesis starts in a small compartment surrounded by the basal chaetoblast and four follicle cells. Initially a group of microvilli emanating from the chaetoblast preforms the rostrum. Next, stout microvilli appear adrostrally, each preforming a spine of the capitium. When both structures have been formed, the longitudinal axis of the anlage shifts, because the actin filaments inside the microvilli reorientate and initiate formation of the manubrium. During this initial phase of chaetogenesis the anlage sinks into the chaetoblast, until the latter finally enwraps the anlage, except the tip of the rostrum. The chaetoblast now generates microvilli that face the new setal structures and preform the hood. During further development the microvilli separate into two layers, an inner and an outer one. The inner layer of microvilli merges with the manubrium prior to the outer layer. Addition of setal material occurs between the bases of the microvilli and elongates the manubrium until it extends beyond the epidermal surface. The microvilli, which have continuously been withdrawn from the seta during chaetogenesis, remain in the basal section. Specific morphogenetic and structural correspondence between the hooked setae of species of Maldanomorpha, Psammodrilida and Oweniida, the uncini of species of the Sabellida, Terebellida and Pogonophora, and the hooded hooks of species of Capitellidae justify the hypothesis that all these setae are homologous. This hypothesis implies the existence of a monophyletic group consisting of all polychaetous Annelida with such setae. Accepted: 16 December 1997     

Ultrastructure of the epidermis and digestive tract inSebastes embryos,with special reference to the uptake of exogenous nutrients

Synopsis Ultrastructural features of the epidermis and rectum were studied inSebastes schlegeli andS. melanops during the late stages of embryonic development, to confirm uptake of maternal substances. Ruthenium red (RR) and horseradish peroxidase (HRP) were used at fixation and in live embryos, respectively. Epidermal tissue of embryos after developmental stage 24 comprised two squamous cell layers. The outer, thinner cells and their intercellular spaces were easily infiltrated with RR, but the inner cells had no RR deposition. The HRP was not incorporated into the epidermis except in a few outer cells, which had well-developed microvillous projections of cytoplasm. Sacciform cells, chloride cells, and mucous cells distributed in the inner layer but protruding to the epidermal surface had no intracellular RR and HRP depositions. The rectal cells of embryos at about developmental stage 28 had many globular inclusions containing electron-dense substances. The rectal cells were found to take up and digest HRP actively. It is suggested that the embryonic epidermis is structurally loose and takes up low weight molecules, while rectal cells, after the opening of the mouth, actively ingest exogenous, high weight molecules.     

DEVELOPMENT OF MUCILAGINOUS SURFACES IN EUGLENOIDS. I. STALK MORPHOLOGY OF COLACIUM MUCRONATUM1

The envelope and stalk of Colacium mucronatum Bourr. & Chad, were examined in living cells with light microscopy and in fixed preparations with scanning electron microscopy using critically point dried (CPD) and freeze dried (FD) preparations. The envelope of palmelloid cells is formed over the entire cell surface by many individual strands attached at right angles to areas of articulation of the pellicular strips. Strands were observed to anastomose on the posterior tip of otherwise naked cells. Stalks of living cells in India ink preparations had an optically dark inner core with a lighter outer sheath. In FD stalks a definite inner core was not evident, whereas CPD stalks had an outer surface composed of thick strands which may be the collapsed and aggregated strands of the FD stalks. In both there was also an amorphous matrix. The stalk forms from the aggregation of many strands from the anterior cell tip back to a point encompassing the cell surface anterior to a cross section of the tip 9 μm diam. The outer surface of the stalk comes from the pellicular surface joining that area and the core from the cell tip in the area of the canal opening. Any possible participation of the inner canal surface in stalk formation could not be determined because of the great density of the mucilage at the cell-tip/stalk junction.     

Development of Fetal Yawn Compared with Non-Yawn Mouth Openings from 24–36 Weeks Gestation

Background

Although some research suggests that fetuses yawn, others disagree arguing that is it simple mouth opening. Furthermore there is no developmental account of fetal yawning compared with simple mouth opening. The aim of the present study was to establish in a repeated measures design the development of fetal yawning compared with simple mouth opening.

Methodology/Findings

Video recordings were made of the fetal face and upper torso visualized by means of 4D full frontal or facial profile ultrasound recordings. Fifteen healthy fetuses were scanned four times at 24, 28, 32 and 36 weeks gestation. Yawning was distinguished from non-yawning in terms of the length of time it took to reach the apex of the mouth stretch, with yawns being defined as more than 50% of the total time observed. To assess changes in frequency, a Poisson mixed effects model was fitted to the count of number of yawn and simple mouth opening events with age and gender as fixed effects, and person as a random effect. For both yawns and simple mouth openings a smooth varying age effect was significant. The number of yawns observed declined with age from 28 weeks gestation, whereas simple mouth openings were less frequent and the decline was observed from 24 weeks. Gender was not significant either for yawn and simple mouth openings.

Conclusions/Significance

Yawning can be reliably distinguished from other forms of mouth opening with the potential of using yawning as an index of fetal healthy development.     

Levisunguis subaequalis n. g., n. sp., a tongue worm (Pentastomida: Porocephalida: Sebekidae) infecting softshell turtles, Apalone spp. (Testudines: Trionychidae) in the southeastern United States

A new tongue worm (Pentastomida) belonging to the Sebekidae Sambon, 1922 (Porocephaloidea Sambon, 1922) is described based on exemplars collected from softshell terrapins Apalone spinifera aspera (Agassiz) and Apalone ferox (Schneider) in the southeastern United States; a new genus is erected to accommodate the new species. The new species belongs in the Sebekidae because adults possess four simple hooks arranged in a trapezoid pattern on the ventral surface of the cephalothorax, a mouth opening between the anterior and posterior pairs of hooks, a terminal anus, an elongated uterus with preanal uterine pore, and a Y-shaped seminal vesicle. Nymphs possess geminate hooks, and the new species has an aquatic life-cycle in which nymphs become encapsulated in the body cavity of a freshwater fish and mature in the lungs of a terrapin. The new genus is distinct from other genera in the Sebekidae primarily by differences in hook morphology and the fact that representatives use a terrapin as a definitive host. Nymphs infecting fish and presumed to be the new species matured as postlarval juveniles conspecific with the new species when they were fed to the eastern mud turtle, Kinosternon subrubrum (Lacépède). Nymphs of the new species are anatomically similar to but larger than nymphs of Sebekia mississippiensis Overstreet, Self & Vliet, 1985 found in the mesentery of fishes captured in Florida, U.S.A. Adults of the new species differ from those of S. mississippiensis based on hook features, chloride cell pore pattern on annuli, body size, and use of a turtle rather than crocodilian definitive host. The new species is the third North American member of the Sebekidae.     

Stratification and age-related differences in blubber fatty acids of the male harbour porpoise (Phocoena phocoena)

Fatty acid composition of blubber was determined at four body sites of 19 male harbour porpoises. A total of 65 fatty acids were quantified in each sample. The array of fatty acids contained in harbour porpoise blubber was similar to those found in other marine mammals. While chemical composition of total blubber was uniform over the body, with the exception of the caudal peduncle, vertical stratification was evident between the deep (inner) and superficial (outer) blubber layers. Fatty acids with chain lengths shorter than 18 carbons were present in significantly greater amounts in the outer blubber layer, while the longer-chain unsaturated fatty acids were more prevalent in the inner layer. This distribution suggests that the inner blubber layer is more active metabolically than the outer layer in terms of lipid deposition and mobilization. The degree of stratification between the two layers appears to increase with age, indicating a predictable turnover in the blubber layer of male porpoises. Harbour porpoise blubber contained high levels (2–27%) of isovaleric acid in the outer blubber layer, and these levels were positively correlated with age.Abbreviations Caud caudal dorsal body site - GC gas chromatograph - FA fatty acid(s) - IUPAC International Union of Pure and Applied Chemistry - PUFA polyunsaturated fatty acid(s) - II dor II dorsal body site - III dor III Dorsal body site - II Ven II ventral body site     

Comparative morphology of the oocyte surface and early development in four characiformes from the São Francisco River,Brazil

Early development from the egg fertilization to complete resorption of the yolk‐sac is a critical period in the life cycle of teleost fish. Knowledge of this process provides essential parameters for aquaculture and identification of spawning sites in the wild. In the present study, a comparative morphological analysis of the oocyte surface as well as early development was performed in four commercially valuable species from the São Francisco River: Brycon orthotaenia, Leporinus obtusidens, Prochilodus argenteus, and Salminus franciscanus. Stripped oocytes, embryo, and yolk‐sac larvae were analyzed by scanning electron microscopy (SEM) and histology. A set of 10 lectins was used for investigation of lectin‐binding pattern in oocytes. In the four species, the outer layer of the zona radiata reacted to most lectins, indicating complex polysaccharides at the oocyte surface while no reactivity was detected in the inner zona radiata and yolk globules. Typical structural arrangements were recognized at the micropylar region by SEM. The four species showed nonadhesive eggs, short embryonic period (18–20 h at 24 ± 1°C), and poorly developed larvae at hatching. At 24 h posthatching (hph), larvae of the four species had neuromasts on the body surface. Rudimentary cement glands for larval attachment were identified on the cephalic region at 24 and 48 hph in B. orthotaenia and S. franciscanus, and following they were in regression. The time for whole yolk resorption varied among species from 48 to 120 hph, occurring earlier in S. franciscanus, followed by B. orthotaenia, P. argenteus, and L. obtusidens. The formation of the digestive tract and the mouth opening indicated initiation of exogenous feeding 24 h before complete resorption of the yolk. Together, our data indicate similarities in the early development among species that may be related to the life cycle strategies and phylogeny. J. Morphol. 276:1258–1272, 2015. © 2015 Wiley Periodicals, Inc.