Laboratory-reared Specimens Research Articles

Development of the cranium in the large African hexaploid barb Labeobarbus (=Barbus) intermedius (Cyprinidae; Teleostei)

Developmental information on the structure and composition of the cartilaginous and bony skull in the large African barb Labeobarbus (=Barbus) intermedius (Teleostei; Cyprinidae) is provided. Sequences of cartilages and bones appearance from a large series of cleared and Alizarin red- and Alcian blue-stained laboratory-reared specimens ranging from prehatching larvae to juvenile stages are described. Comparisons of cranial development are made among cyprinids: L. intermedius, Danio rerio, Barbus barbus, and Cyprinus carpio.

Non-destructive species identification of Drosophila obscura and D. subobscura (Diptera) using near-infrared spectroscopy

The vinegar flies Drosophila subobscura and D. obscura frequently serve as study organisms for evolutionary biology. Their high morphological similarity renders traditional species determination difficult, especially when living specimens for setting up laboratory populations need to be identified. Here we test the usefulness of cuticular chemical profiles collected via the non-invasive method near-infrared spectroscopy for discriminating live individuals of the two species. We find a classification success for wild-caught specimens of 85%. The species specificity of the chemical profiles persists in laboratory offspring (87–92% success). Thus, we conclude that the cuticular chemistry is genetically determined, despite changes in the cuticular fingerprints, which we interpret as due to laboratory adaptation, genetic drift and/or diet changes. However, because of these changes, laboratory-reared specimens should not be used to predict the species-membership of wild-caught individuals, and vice versa. Finally, we demonstrate that by applying an appropriate cut-off value for interpreting the prediction values, the classification success can be immensely improved (to up to 99%), albeit at the cost of excluding a considerable portion of specimens from identification.

Larval development of the Iberian cyprinid Anaecypris hispanica

Anaecypris hispanica is the most threatened cyprinid fish in the Iberian Peninsula. The distribution of this Iberian cyprinid is restricted to the Guadiana River drainage and a single tributary in the Guadalquivir River and has been rapidly diminishing over the past thirty years. Several A. hispanica populations have been depleted to a point which individual densities are below a level where adults can be detected, making it necessary to identify A. hispanica larvae to assess populations and to make declarations about local extinctions. This work is the first detailed description of the larval stages of A. hispanica from egg to stage 5 observed from laboratory-reared specimens. The eggs are spherical, adhesive, and transparent, and they measure 1.4 mm (mean diameter). The larvae hatch 72 hours after activation and measure 5.0 mm (mean total length-TL). The notochord flexion occurs at 5.9 mm (mean TL), and larvae have 38-39 total myomeres. Anaecypris hispanica larvae have little cephalic pigmentation with few melanophores anterior to the eyes, although pigmentation intensifies during development. Identifying features are presented here that will enable researchers to distinguish A. hispanica from other sympatric species. This information will allow us to identify larvae and can help to assess whether this species is present at locations where adults are not detected.

Spawning habitat and early development of Luciogobius ryukyuensis (Gobiidae)

Egg masses of Luciogobius ryukyuensis were found in spawning grounds around the lowest reach of the adult’s habitat in the tidally influenced area of streams on Okinawa Island. The eggs were attached to the underside of stones and were cared for by a solitary male fish. The number of eggs within an egg mass was 191–1368. The eggs were elliptical, measuring 2.0–2.6 mm in length, and 0.6–0.8 mm in width. Early development of L. ryukyuensis was described from laboratory-reared specimens. Newly hatched larvae, measuring 2.8–3.3 mm in body length, had an open mouth, pigmented eyes, pectoral fin buds, an orange-colored yolk sac, and characteristic melanophores along the dorsal and ventral midlines of the body. The yolk was completely absorbed at days 2–3. Notochord flexion began at day 10 and was completed at day 15. The fish started settling on the bottom of the tank at day 34 (14.1 mm in body length) when the body surface started to be covered by intense pigmentation. The eggs and newly hatched larvae of L. ryukyuensis were of standard size of the genus and their morphologies closely resemble those of L. guttatus.

The influence of adult worm age and definitive host on the transmission of Echinostoma caproni: egg hatchability and miracidial infectivity

We analysed the influence of different ages of Echinostoma caproni adult worms reared in different definitive host-species on egg hatchability and miracidial infectivity. Eggs obtained from 2-, 4- and 6-week-old adult worms collected from rats, hamsters and mice, hatched miracidia that were used to infect laboratory-reared specimens of Biomphalaria glabrata. Highest egg hatchability was obtained with eggs derived from hamsters and mice. Egg hatchability did not seem to be affected by the age of E. caproni adult worms. Miracidial infectivity was not affected by the definitive host species. However, miracidial infectivity was affected by the age of adult worms when they developed in the mice intestine. The long period of miracidial infectivity in hamsters revealed this definitive host as the most suitable for experimental development of the life cycle and parasite transmission.

Growth and morphological development of laboratory-reared larval and juvenile three-spot gourami Trichogaster trichopterus

Morphological development, including the body proportions, fins, pigmentation and labyrinth organ, in laboratory-hatched larval and juvenile three-spot gourami Trichogaster trichopterus was described. In addition, some wild larval and juvenile specimens were observed for comparison. Body lengths of larvae and juveniles were 2.5 ± 0.1 mm just after hatching (day 0) and 9.2 ± 1.4 mm on day 22, reaching 20.4 ± 5.0 mm on day 40. Aggregate fin ray numbers attained their full complements in juveniles >11.9 mm BL. Preflexion larvae started feeding on day 3 following upper and lower jaw formation, the yolk being completely absorbed by day 11. Subsequently, oblong conical teeth appeared in postflexion larvae >6.4 mm BL (day 13). Melanophores on the body increased with growth, and a large spot started forming at the caudal margin of the body in flexion postlarvae >6.7 mm BL, followed by a second large spot positioned posteriorly on the midline in postflexion larvae >8.6 mm BL. The labyrinth organ differentiated in postflexion larvae >7.9 mm BL (day 19). For eye diameter and the first soft fin ray of pelvic fin length, the proportions in laboratory-reared specimens were smaller than those in wild specimens in 18.5–24.5 mm BL. The pigmentation pattern of laboratory-reared fish did not distinctively differ from that in the wild ones. Comparisons with larval and juvenile morphology of a congener T. pectoralis revealed several distinct differences, particularly in the numbers of myomeres, pigmentations and the proportional length of the first soft fin ray of the pelvic fin.

Embryonic development and morphology of eggs and newly hatched larvae of Pacific herring Clupea pallasii

The embryonic development and morphology of eggs and newly hatched larvae of the Pacific herring Clupea pallasii were described using laboratory-reared specimens originating from the Miyako Bay stock. The eggs were almost spherical in shape, 1.33–1.46 mm (mean: 1.38 mm) in diameter, and had a thick adherent chorion. They had a segmented pale yellow yolk, no oil globule, and a relatively wide perivitelline space. A subgerminal cavity was observed during the gastrula period, whereas the blastocoel did not appear. Mass hatching occurred by 271 h 45 min after fertilization, and the newly hatched larvae were 7.1–7.7 mm (mean: 7.5 mm) in total length with 53–56 myomeres at 9.6°C. The embryonic development of Pacific herring was substantially similar to that of zebrafish Danio rerio, American shad Alosa sapidissima, as well as Atlantic herring Clupea harengus, and generally followed the basic developmental pattern of teleosts. However, Pacific herring larvae hatched at a more developed stage than some other clupeoids, such as Japanese sardine Sardinops melanostictus, and the progressed developmental stage at hatching could be interpreted as an advanced adaptation.

Description of Hymenolepis microstoma (Nottingham strain): a classical tapeworm model for research in the genomic era.

BackgroundHymenolepis microstoma (Dujardin, 1845) Blanchard, 1891, the mouse bile duct tapeworm, is a rodent/beetle-hosted laboratory model that has been used in research and teaching since its domestication in the 1950s. Recent characterization of its genome has prompted us to describe the specific strain that underpins these data, anchoring its identity and bringing the 150+ year-old original description up-to-date.ResultsMorphometric and ultrastructural analyses were carried out on laboratory-reared specimens of the 'Nottingham' strain of Hymenolepis microstoma used for genome characterization. A contemporary description of the species is provided including detailed illustration of adult anatomy and elucidation of its taxonomy and the history of the specific laboratory isolate.ConclusionsOur work acts to anchor the specific strain from which the H. microstoma genome has been characterized and provides an anatomical reference for researchers needing to employ a model tapeworm system that enables easy access to all stages of the life cycle. We review its classification, life history and development, and briefly discuss the genome and other model systems being employed at the beginning of a genomic era in cestodology.

Early developmental stages of the scorpaenid fish, Scorpaena miostoma, reared in the laboratory

Embryonic development and morphology of the eggs, egg masses and larvae of the scorpaenid fish,Scorpaena miostoma are described on the basis of the laboratory-reared specimens. The gelatinous egg mass is not bilobed but simple, oval and balloon-like in shape. It usually floats at or near the surface. The individual egg is colorless and ovoid in shape, measuring 0.86 × 0.75 mm. Hatching occurs between ca. 34 and 40 hours after spawning at the water temperature of 22–24°C. A newly hatched larva measures 1.55 mm in notochord length and has ca. 25 myomeres. The finfold is balloon-like in shape and almost completely covers the larval body. Minute “cell-like” granules scatter on the findfold.

Morfología de los estados inmaduros y adulto de Neohydatothripsdenigratus (De Santis) (Thysanoptera: Thripidae), con datos sobre su biología

The adult female of Neohydatothrips denigratus (De Santis) is redescribed, the male and immature stages (larva, prepupa and pupa) are described for the first time, and aspects of the biology of this species are made known. Descriptions of the different stages of development were made from laboratory-reared specimens on using twigs of Phaseolus vulgaris as a feeding and oviposition substrate. Neohydatothrips denigratus undergoes its life cycle on the leaves of P. vulgaris, no immature stages were found in flowers or fruits. Under controlled conditions (21+/-2 masculineC; 80+/-4% RH; photophase: 12 h), this species needed 21.6+/-1.60 d to complete development (egg: 7.0+/-1.00 larva I: 3.7+/-1.40; larva II: 4.2+/-1.10; prepupa: 1.8+/-0.70, pupa: 5+/-1). Longevity was 6.0+/-2.00 days and observed sex ratio was 2:1. From the sixteen plants belonging to ten families recorded as hosts to this species, larvae were found only on two species of Fabaceae and one of Solanaceae.

Number and Duration of Zoeal Stages of the Hydrothermal Vent Crab Gandalfus yunohana from Laboratory Reared Specimens

Abstract The hydrothermal vent crab Gandalfus yunohana is found along the Izu-Ogasawara Arc in the north-western Pacific at depths from 420 to 1400 m. To study the larval developmental characteristics of this vent endemic species, we collected adult crabs from a depth of 445 m in May 2005 from the Kaikata Seamount (26°42.607′N, 141°04.457′E). These individuals were maintained at atmospheric pressure and temperature (15 and 18°C) for several months, until two females spawned and released larvae. Larvae were maintained at atmospheric pressure and at five different temperatures ranging from ∼18 to 30°C and fed Artemia sp. At ∼18°C, no larvae survived until the second zoeal stage. Some larvae reached the second or third zoeal stages when reared at ∼21°C. At 24-30°C, six individuals metamorphosed into the megalopal stage following a fifth or sixth zoeal stage 34-60 d after hatching. Megalopae swam actively, but they eventually died 58-104 d after hatching and showed no signs of moulting into the juvenile crab ...

The pupal exuviae of Chironomus crassimanus Strenzke (Diptera: Chironomidae), an acid-resistant species from Germany

The first descriptions of the pupal exuviae of Chironomus crassimanus Strenzke, 1959 were based on mixed populations of Chironomus which did not allow a proper recognition of their features in the available taxonomical keys. This paper describes the morphological characteristics of Ch. crassimanus based on laboratory-reared specimens. A more comprehensive description is ensued and ecological information on the species is also provided.

Morphological Development of the Commensal Pea Crab (Arcotheres Sp.) in the Laboratory Reared Specimens

Abstract Thirty-seven crabs (8 males and 29 females) of the genus Arcotheres, which inhabit the sessile bivalve Barbatia virescens (Reeve, 1844), were reared for 135 days in the laboratory and their morphological development was described. There was a strong size correlation between female crabs and their host bivalves. During laboratory culture, seven males and 18 females molted once, and one male and four females molted twice. The crabs showed little growth, perhaps because the crabs and bivalves were not fed during the study and because crab growth may be restricted by the host size. One small female molted from pre-hard stage to hard stage and progressed further to Stage II. Some adult females in Stage III or IV developed swimming setae following the molt. In past studies, only one metamorphosis was detected within a crab, and adult females were not thought to develop swimming setae. Thus, our study is the first to detect successive changes in body form within a crab. Furthermore, this study confirmed...

Morphology of the first instar larva and of the egg ofLabidostomis longimana (Linnaeus, 1761) and ofLabidostomis tridentata (Linnaeus, 1758) (Coleoptera, Chrysomelidae, Clytrinae), with a key to clytrine genera with the first instar larva known

The first instar larva and the egg of Labidostomis longimana (Linnaeus, 1761) are described and illustrated and these of Labidostomis tridentata (Linnaeus, 1758) are re-described and illustrated from laboratory-reared specimens. The descriptions are compared with one another and with those of the same developmental stages in species of the genus known in the literature, i.e. the larva of Labidostomis tridentata (Linnaeus, 1758) and the eggs of L. taxicornis (Fabricius, 1792), and L. cyanicornis Germar, 1822. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

ECHINOSTOMATID LARVAL STAGES IN LYMNAEA VIATRIX (GASTROPODA: PULMONATA) FROM SOUTHWEST PATAGONIA, ARGENTINA

The partial life cycle of an echinostomatid found in Lymnaea viatrix from Patagonia, Argentina, was experimentally clarified. Emerging cercariae were exposed to laboratory-reared specimens of Biomphalaria sp. Metacercariae obtained from both naturally and experimentally infected snails were force-fed to chicks. Specimens recovered from the chicks belong to Echinoparyphium sp. on the basis of morphological features. The studied species possesses 43 collar spines arranged in 4-4-27-4-4 at all stages, a cercariae with over 100 small corpuscles in the excretory system, a cercariae tail without finfolds, and a metacercariae with a thin cyst wall. The present species cannot be assigned to Echinoparyphium megacirrus despite their morphological similarity because of differences in the habitats of L. viatrix and the intermediate hosts of E. megacirrus, namely Chilina dombeiana, Diplodon chilensis, and Temnocephala chilensis. More information on some life cycle stages and on the ecology of the intermediate hosts is needed to clarify the taxonomic status of the parasite. This study represents the first detailed description of parasites other than Fasciola hepatica in L. viatrix from Argentina.

Juvenile morphology of the xanthid crab Leptodius exaratus (H. Milne-Edwards, 1834) (Decapoda: Brachyura), with notes on the appearance of sexual dimorphism

Summary The morphometrical and meristic features of the carapace, cephalic appendages (antenna, antennule), mouthparts (maxillule, maxilla, first-third maxillipeds), sternum, pereiopods, abdomen, and pleopods of juveniles and the onset of morphological sexual dimorphism were described for the xanthid crab Leptodius exaratus (H. Milne Edwards, 1834), based on laboratory-reared and wild adult specimens collected from Tateyama Bay, Japan. First instar juveniles shared some of the features of adults (e.g. gross appearance of the carapace and cheliped propodus proportions), but differed from adults on almost all other morphological parameter examined. Morphological development was still not complete at the ninth instar; extrapolation from the rate of morphological changes between instars 1–9 suggests that L. exaratus requires about 13 ecdyses to transform into adults, including development of reproductive structures. Differences in the number and morphology of pleopods and abdomen width allowed early distinction of the sexes. Thus, males formed gonopods in the first abdominal somite and lost the paired vestigial pleopods in somites 3–5 from the fourth instar; females retained the pleopods in somites 2–5, but these became biramous and had increased setation. The abdomen grew wider in females than in males from the fifth instar. Several morphological features of juveniles have phylogenetic and taxonomic implications: carapace motifs clearly place L. exaratus in the superfamily Xanthoidea, whereas the patterns of setation in the scaphognathite and first maxilliped epipod allow separation of this (xanthid) species from crabs of other Xanthoidean families.

Physiological tolerance of marine calanoid copepod eggs to sulphide

The impact of anoxia and anoxia-sulphide (8 different numeric sulphide concentrations, ranging from 10 µmol l -1 to 10 mmol l -1 ) on hatching of subitaneous eggs of the planktonic copepod Acartia tonsa Dana was evaluated. The experiments were consequently conducted at pH 8.1. Subita- neous eggs, spawned by laboratory-reared specimens, were exposed to anoxia and anoxia-sulphide for different periods (3, 7, 14, 30, 60, 120, 180 and 240 d) and then transferred to normoxic conditions. Short-term (3 to 60 d) exposure to anoxia or anoxia-sulphide did not significantly affect the hatching success of the eggs, but hatching generally declined with increasing length of exposure. After 60 d of exposure there were significant differences between the effects caused by anoxia and anoxia-sul- phide (sulphide concentrations ≥250 µmol l -1 ). After 240 d of exposure there were significant differ- ences in hatching between eggs treated with anoxia and those with anoxia-sulphide (all sulphide concentrations). A short-term experiment, where subitaneous eggs were simultaneously exposed to oxygen and different sulphide concentrations, indicated that sulphide is capable of crossing the eggshell. The metabolic rate of eggs exposed to normoxic conditions was 1.86 ± 0.57 µJ h -1 . Eggs exposed to anoxia had a metabolic rate of 0.08 ± 0.02 µJ h -1 , whereas eggs exposed to anoxia and 14.7 mmol l -1 sulphide had a metabolic rate of 0.25 ± 0.001 µJ h -1 . Based on the metabolism ex- periments and the fact that internal egg pH was ~6, an unknown sulphide defence mechanism is suggested to be present in A. tonsa eggs.

Dynamics of feeding and defecation in Triatoma vitticeps (Stal, 1859) (Hemiptera, Reduviidae, Triatominae) and its potential in the transmission of Trypanosoma cruzi

Adults of Triatoma vitticeps infected by flagellates similar to Trypanosoma cruzi are frequently captured by the inhabitants of rural areas in the Brazilian state of Espirito Santo. The dynamics of feeding and defecation were observed in three groups of adult triatomines, consisting of sylvatic T. vitticeps and laboratory-reared specimens of this species and T. infestans. Triatomines were observed from the moment they were presented with an immobilized chicken as a bloodmeal source until 240 min after feeding had ended. Mean times between the end of feeding and defecation for T. infestans, wild T. vitticeps and laboratory-reared specimens of the latter species were 1.2, 21.1, and 64 min respectively. All T. infestans defecated within 10 min of feeding, while only 29.9 of wild and 52.8% laboratory-reared specimens of T. vitticeps did so within this period. These results may explain the low efficiency of T. vitticeps in T. cruzi transmission to man. The shorter time between feeding and defecation in laboratory-reared T. vitticeps may indicate a change in behaviour of this species as a result of adaptation to an artificial environment.

Sitobion graminis Takahashi, 1950 (Hemiptera, Aphididae): first record in Brazil, biological and morphometric parameters

The species Sitobion graminis Takahashi, 1950 (Hemiptera, Aphididae) was first detected in Brazil in 1998, in Curitiba, Parana state, associated with the grass species Erianthus sp., Calamagrotis sp. and Paspalum urvilei. Both the field-collected and laboratory-reared specimens presented a noticeable intrapopulational variation in body and appendix length and in dorso-abdominal sclerotization. This species has been recorded in Malaysia, New Guinea, India, Philippines and Africa, where it colonizes several species of Poaceae. S. graminis differs from other Sitobion species from Brazil associated with grasses, as it presents black cauda and siphunculi and exhibits a constriction in the base of the last rostral segment. Biological data were obtained in the laboratory by rearing newborn nymphs on the inflorescence of the host plants. They passed through four nymphal instars. The mean duration of the nymphal stage was of 11.4 days, with a mortality ratio of 36.5%. The mean pre-larviposition period was of 1.8 days; mean longevity of the females was 25.2 days; and mean fecundity was 18.7 nymphs/female, ranging from 2 to 41 nymphs/female.

Developmental morphology of the cyprinid fish Inlecypris auropurpureus

Embryonic, larval, and juvenile development of a Myanmarese cyprinid fish, Inlecypris auropurpureus, is described from laboratory-reared specimens. The eggs, measuring 0.9–1.0 mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk without oil globules. Hatching occurred 49–56 h after fertilization at 26.2°–27.3°C. The newly hatched larvae, measuring 2.9–3.1 mm in body length (BL) with 17 + 19–20 = 36–37 myomeres, had melanophores on the head and body. A cement organ on the forehead for adhering to objects during the yolk sac and early preflexion larval stages was distinctive. The yolk was completely absorbed at 3.6–4.0 mm BL. Notochord flexion was initiated at 5.1–5.6 mm BL and finished at 7.1 mm BL. Aggregate numbers of all fin rays were completed at 14 mm BL. Squamation was initiated midlaterally on the anterior trunk at 14 mm BL and completed at 27 mm BL. Although the eggs of I. auropurpureus resembled those of the closely related species Chela dadiburjori, Danio rerio, and Devario malabaricus, they differed from those of Danio rerio and Devario malabaricus in having a narrower perivitelline space. The larvae and juveniles of I. auropurpureus were also similar to those of C. dadiburjori, Danio rerio, and Devario malabaricus in general morphology, but they differed from the latter three species in having a series of dark blotches laterally on the body in the juvenile stage. Moreover, I. auropurpureus differed from C. dadiburjori in having more myomeres and a near-single row of melanophores on the body along the dorsal midline from the yolk-sac to early postflexion larval stages, from Danio rerio in having a cement organ on the forehead during the yolk-sac and early preflexion larvae, and a single melanophore on the lower eye margin in the early yolk-sac larvae, and from Devario malabaricus in having a single melanophore on the lower eye margin in the early yolk-sac larvae. The presence of a cement organ on the forehead indicates a close relationship among the genera Inlecypris, Chela, and Devario.