Postmarsupial Development Research Articles

Evolution and biogeography of the Haploniscus belyaevi species complex (Isopoda: Haploniscidae) revealed by means of integrative taxonomy

The role of geomorphological features as drivers for benthic deep-sea biodiversity remains poorly understood. By disentangling the putative Haploniscus belyaevi Birstein, 1963a species complex from the abysso-hadal Kuril-Kamchatka Trench (KKT) region in the North-west Pacific Ocean, we aim to shed light on deep-sea differentiation and how it is related to potential bathymetric barriers such as the KKT and the Kuril-Island Ridge (KIR). Our integrative taxonomic approach featured morphological and molecular delimitation methods, also considering the post-marsupial development due to pronounced sexual dimorphism. Mitochondrial 16S and COI markers were sequenced and several molecular species delimitation methods were applied. By combining the different results we were able to delineate six distinct species within the belyaevi complex, including several morphologically cryptic species, and found hints of three additional species groups in the complex. Even though several of these species were distributed across the KKT and/or KIR, limited gene flow and depth-differentiation were indicated supporting previous notions that these geomorphological features play a role in deep-sea benthos speciation.

Uniting what belongs together—Reevaluation of the isopod species Macrostylis grandis and M. ovata using ontogenetic, morphological and genetic evidence

Solid taxonomy is the primary basis for many further-reaching studies in biology, such as biogeography. Here we reevaluate the taxonomic status of two species of the isopod crustacean family Macrostylidae Hansen, 1916, Macrostylis grandis Birstein, 1970 and M. ovata Birstein, 1970. Although they differ significantly in size and other morphological characteristics they share, amongst other character states, an oval habitus which makes them stand out from congeners. We test the hypothesis that M. grandis and M. ovata may represent different life stages of a single species. While some of the newly available specimens collected in the northwest Pacific Ocean during the KuramBio I and SokhoBio expeditions could be morphologically identified as either of the two described species, others represented intermediate forms. Based on this new dataset we provide (1) a complemented morphological taxonomic description of M. grandis and (2) reconstruct parts of the postmarsupial development and (3) analyse their genetic distances. Results of all three analyses were used to reevaluate the taxonomic status of both species and provided justification for a transfer of M. ovata into synonymy with M. grandis. The updated biogeography resulting from the new taxonomic status and samples reveals a distribution at abyssal and upper hadal depths across the Kuril Kamchatka Trench with no indication that the trench may represent a barrier for this species.

Biologic and Ecologic Aspects of Sinelobus stanfordi (Richardson, 1901) (Crustacea, Tanaidacea) in the Martín García Island Natural Reserve, Río de la Plata, Argentina

We investigated the biology and ecology of the tanaidacean Sinelobus stanfordi from the littoral water of Martín García Island at five sites along the coast chosen for their substrate characteristics, and classified the individuals according to size (mm) and ectosomatic characterinalysisstics as: manca III (0.60-1.19), juvenile male and female I (0.90-1.49), juvenile female II and copulatory male I (1.2-1.79), preparatory female I (1.8-2.39), preparatory female II (2.40-2.99), copulatory female I (2.40-2.69), copulatory female II (2.99-4.19), ovigerous female (1.80-3.59), copulatory male II (1.5-1.79), copulatory male III (2.10-2.69) and copulatory male IV (2.40-3.89). The smallest female with rudimentary ovisacs measured 1.84 mm. The tanaid density ranged from 0 to 10,548 ind.m-2. The average female-to-male sex ratio was 3.04:1. An abundance analysis indicated no significant differences among the sampling sites (X2 =4.037, p>0.001), while the fecundity (number of eggs) did not vary significantly with female size (r2 =0.2164, n = 19). The almost permanent presence of all developmental stages during every season of the year suggested a likely continuous year-long reproduction of S. stanfordi. Relationship between the water variables and S. stanfordi populations: The lower than optimal average electrical conductivity (160.24 μS.cm-1) for the species did not seem to limit the population-growth kinetics. The postmarsupial development throughout almost all the stages evidenced a significant positive correlation with pH. The soluble-reactive-phosphorus levels were within the low tolerance values as well as the NO-3 and the NH4 + and both close to optimal along with the near-optimal percent saturation of oxygen.

Development of calcium bodies in Hylonsicus riparius (Crustacea: Isopoda)

Calcium bodies are internal epithelial sacs found in terrestrial isopods of the family Trichoniscidae that contain a mineralized extracellular matrix that is deposited and resorbed in relation to the molt cycle. Calcium bodies in several trichoniscids are filled with bacteria, the function of which is currently unknown. The woodlouse Hyloniscus riparius differs from other trichoniscids in that it possesses two different pairs of calcium bodies, the posterior pair being filled with bacteria and the anterior pair being devoid of bacteria. We explored the development of these organs and bacterial colonization of their lumen during the postmarsupial development with the use of optical clearing and whole-body confocal imaging of larval and juvenile stages. Our results show that calcium bodies are formed as invaginations of the epidermis in the region of intersegmental membranes during the postmarsupial development. The anterior pair of calcium bodies is generated during the first postmarsupial manca stage, whereas the posterior calcium bodies first appear in juveniles and are immediately colonized by bacteria, likely through a connection between the calcium body lumen and the body surface. Mineral is deposited in calcium bodies as soon as they are present.

SEGUIMIENTO DEL CICLO REPRODUCTIVO EN EL ANFIPODO MARINO PARHYALE HAWAIENSIS (DANA) (GAMMARIDEA: HYALIDAE)

The amphipod Parhyale hawaiensis was collected in copulative and ovate states in the rocky shore of Cartagena (Colombian Caribbean). Six phases were defined during the fecundation period. Five characteristic stages in the evoution of the eggs and embryos were established for the marsupial development. It was defined the post-marsupial development as consisting of four life periods, based on variations in total length, head length, antennal article number, shape of gnathopod two, and the.increase in number of medial marginal thorns in the gnathopod two and pereiopods. The fecundation process and the embryologic development lasted sixteen days. Embryos developed simultaneously in number of13 per female. The release of juveniles was asynchronous. In the male, sexual dimorphism was reached after four weeks as evidenced by the size and shape of the gamopod 2 and the number of articles in antennaes 1 and 2.

The postmarsupial development of Porcellio siculoccidentalis, with some data on reproductive biology (Crustacea, Isopoda, Oniscidea)

In the broader context of research on the Sicilian Porcellio imbutus-complex, the postmarsupial development of Porcellio siculoccidentalis Viglianisi, Lombardo & Caruso, 1992 was studied in detail. This research was conducted in the laboratory under controlled conditions, allowing us to follow the stages of development, from the formation of the marsupium in ovigerous females until the larval stages and development of the seventh pair of legs. The timing of developmental stages and the morphological modifications of appendages in the postmarsupial manca stages (M I–M III) are described. The manca stage M I had a duration of about one hour. Ovigerous females were collected and reared separately, and the number of parturial molts in the absence of males was counted. The results showed a maximum of four successive parturial molts. Fecundity and fertility were evaluated as the number of eggs and embryos, respectively, inside the marsupium of the ovigerous females. Both parameters were positively correlated with the size of the females. The maximum numbers of eggs and embryos in the marsupium were 113 and 141, respectively. Data describing the total number of postmarsupial mancas released per month indicated that the highest release occurred in April.

Redescription and postmarsupial development of Apseudopsis latreillii (Crustacea: Tanaidacea)

Apseudopsis latreillii is a common tanaidacean species widely-distributed in the north-east Atlantic, but its diagnostic characters remain unspecified. Furthermore, intraspecific variation in relation to its developmental stages has not been described. Knowledge about this variation is needed owing to the difficulty of identification of the significant number of juvenile specimens within samples, particularly when sympatric with other apseudid species. Specimens from three different localities of the north-east Atlantic have been examined, and the size of 766 individuals has been measured. Study of postmarsupial development shows that the manca II is followed by two juvenile stages before reaching maturity. Males present two possible morphologies. After a preparatory stage, females pass through a sequence of copulatory instars followed by intermediate stages in which the female loses the ovisac after manca release. Characters allowing the distinction of A. latreillii specimens regardless of developmental stage are the combination of a pointed and downturned rostrum, pereonites without apophyses, three ventral spines on the pereopod 1 propodus, and one dorsodistal spine on the merus.

Post-marsupial development of Hyalella pleoacuta (Crustacea: Amphipoda): stages 1-4

The goal of this study is to describe and compare the initial stages of the post-marsupial development of Hyalella pleoacuta González, Bond-Buckup & Araujo, 2006, prior to the development of sexual dimorphism. Ovigerous females were collected in São José dos Ausentes, RS, Brazil and kept in laboratory. Juveniles were kept separately after emerging from the marsupium and were monitored daily for the presence of exuvia. Individuals from post-marsupial stages (S) 1 to 4 were dissected and illustrated. Cuticular structures were observed through SEM. Twenty three types of setae, one type of setule, two types of pores, two types of denticles and one type of penicilium were found. Cuticular structures undergo modification through development in the matters of haste size, number and size of setules, and formation of the polygonal pattern, although there is no change from one type to another. Gnathopods and antennae are the appendages that go through more modifications. The articles number of the flagellum is constant until S2. The size of the coxal plate of gnathopods in relation to the propodus has a tendency to increase throughout the stages. The uropod proportion becomes smaller in S3 when compared to S1. The number of serrate setae in the external plate of maxilla 1 varies up to S4, being different from the adult whose number is 9. The telson modifies its shape but its setae number is constant.

Postmarsupial development of Atlantoscia floridana (van Name, 1940) (Crustacea, Isopoda, Oniscidea): sexual differentiation and size at onset of sexual maturity

Summary The postmarsupial development of Atlantoscia floridana (van Name, 1940) was studied, with emphasis on the sexual differentiation and maturity. Samples were obtained in the Reserva Biológica do Lami, Porto Alegre, RS, Brazil, during 2000 and 2002. Collected animals were reared in the laboratory under temperatures of about 20±1°C and observed daily. Animals preserved in 70% ethanol were used to analyze sexual maturity. Growth was monitored as each animal moulted for evidence of sexual differentiation. The development of the male genitalia and the female genital pore was described across the different juvenile stages. Female sexual maturity was estimated to occur at a minimum size of 1.04 mm cephalothorax width. Male sexual maturity was estimated from the morphometric relationship between cephalothorax width and length of the genital papilla and indicated the puberal moult to occur at a minimum size of 0.77 mm cephalothorax width. Identification of the size at which sexual maturity occurs allows recognizing the postmarsupial juvenile stages of both males and females: JUI to JU III for males and JU I to JU VI for females. Males reach sexual maturity in approximately 1.5 months after leaving the marsupium, and females in about 3 months.

Postmarsupial development of Atlantoscia floridana (van Name, 1940) (Crustacea, Isopoda, Oniscidea): the manca stages

In this paper we describe the postmarsupial development of the manca stages of Atlantoscia floridana (van Name, 1940). Ovigerous females were collected in Reserva Biológica do Lami, Porto Alegre, RS, Brazil and separately reared in small containers at 20°C (±1°C). After birth each newborn (manca I) was reared separately in order to observe the subsequent moults. In a period of about 12 h the animals underwent the first moult. The manca II stage lasts 9.16±1.57 days while manca III takes up a period of 9.96±1.05 days. Growth was observed through measurements of cephalothorax width. The three manca stages are described, illustrated and compared with the adults. The main distinguishing characteristics among mancas I, II and III are presented as well as the b/c and d/c co-ordinates of the noduli laterales.

Life history of Nippoleucon hinumensis (Crustacea: Cumacea: Leuconidae) in Seto Inland Sea of Japan. I. Summer diapause and molt cycle

The life history of the cumacean Nippoleucon hinumensis was investigated in the Seto In- land Sea of Japan from August 1998 to February 2002. The population produced 1 generation per year and recruitment of offspring occurred in April. The post-marsupial period consisted of 8 instars in males and 9 (plus generally 2 repeated instars) in females. Post-marsupial development up to the 4th instar (2nd juvenile stage) was characterized by periodic molting at intervals of 10 d, slow growth rate, and suppression of sexual dimorphism. Thereafter, the juveniles entered a long-term summer dia- pause from mid-May to early December, during which the ambient seawater temperature ranged from 15 to 28°C. Ninety-nine % of the population during the diapause were at the 2nd juvenile stage, and 1% were at the 1st juvenile stage. In December, the cumaceans resumed growth, characterized by a fortnightly molt cycle, until the females began to incubate the first brood in late February. Each molt- ing was highly synchronized among individuals and phased with the lunar cycles. After the end of the summer diapause, sexual dimorphism became apparent, with ovigerous females becoming about 1.2 times larger than adult males. After release of manca larvae in early April, most females incubated a second brood in late April, and then rapidly disappeared due to mortality probably caused by high water temperature. Clutch size was 57.9 ± 9.4 for the first brood and 42.4 ± 7.3 for the second.

Postembryonic development of Apseudes heroae and Allotanais hirsutus (Tanaidacea, Crustacea) in Magellanic and sub-Antarctic waters

Apseudes heroae Sieg, 1986 (Family Apseudidae) and Allotanais hirsutus (Beddard, 1886) (Family Tanaidae) are common Tanaidacea of the southern Magellanic region. The aim of the investigation is to elucidate the postmarsupial development of these tanaid species that differ in their biogeography. Population structures are analysed from size frequency data and from different postembryonic stages of specimens collected in the Atlantic entrance of the Beagle Channel and from the Atlantic continental slope to the south-east. The population of Apseudes heroae shows three age groups, the one of Allotanais hirsutus probably at least three. Some large specimens indicate that the latter sub-Antarctic species might reach an age of several years. Both species are probably gonochoristic, and protandric hermaphroditism was not observed. The fecundity of Apseudes heroae and Allotanais hirsutus was analysed. No significant correlation could be found between cephalothorax width and egg number or number of larvae. For both species hypothetical life cycles are reconstructed. As sub-Antarctic temperatures are low and seasonality is strong in the Magellanic region, it is possible that these species are reasonably adapted in reproduction as shown in some polar species of Isopoda and Cumacea.

Contribution to the knowledge of growth and postmarsupial development of Natatolana borealis (Crustacea: Isopoda)

Postmarsupial development and growth of Natatolana borealis were studied from Skogsvåg and Raknesvåg on the western coast of Norway. Growth was determined from size and instar stage distributions. Growth was also examined in laboratory kept isopods that were collected from Skogsvåg. The postmarsupial instar stages were identified using the number of articles and the position of setae on the flagellum of the first antenna and other morphological features. The mean size of isopods in instar stages 1—3 did not show any significant seasonal variation in Raknesvåg. The estimated growth and mortality rates of males and females were not significantly different. Nine and 11 postmarsupial instar stages were found in material from Skogsvåg and Raknesvåg, respectively. The life span from instar stage 1 to 9 of male and female N. borealis from western Norway was estimated to be 3—4 y. Mortality rate increased significantly from instar stage 9 to 10 of both sexes. Isopods that attained instar stage 10 and instar stage 11 in Raknesvåg, may have lived 4—5 y. The mean size of instar stages 8 and 9 and the size-to-weight relationships were significantly higher in material from Raknesvåg relative to that from Skogsvåg and may have been caused by differences in food access and predation pressure at the two study sites. Specimens sampled from the Bay of Monaco attained smaller adult size than the isopods from the Norwegian population.

Postmarsupial Development of Munnopsurus a Tlanticus (Bonnier, 1896), a Dominant Asellote Isopod From the Upper Continental Slope of the Bay of Biscay

AbstractThe asellote isopod Munnopsurus atlanticus is a dominant species in the bathyal suprabenthic assemblages from the south margin of the Cap-Ferret Trench; it is therefore a valuable subject for studies of postmarsupial development and population biology in bathyal Isopoda. In this introductory paper, its postmarsupial development is described on the basis of size frequency analysis and morphological discrimination. Eight developmental stages are recognized within the Biscayan population: mancas 1-2; manca 3, juvenile and copulatory males; manca 3, juvenile, preparatory and brooding females. The number of successive instars depends on the sex of the individuals; at least 8 instars for the females and 5 instars for the males. The female may be iteroparous, reverting to a preparatory condition before brooding once more. The larger adults are found over muddy sediments, probably reflecting more favourable environmental conditions for growth increment in the deepest part of the investigated area.

The Occurrence of Cymothoa Liannae, a New Species of Cymothoid Isopod From Brazil, With a Comparative Study of Its Post-Marsupial Development

[Ce travail est le resultat d'une etude critique des stades de developpement de Cymothoa liannae (Isopoda, Cymothoidae), espece nouvelle ici decrite. Ce nouveaux cymothoadien a ete trouve sur la cote sud-ouest du Bresil, du Parana jusqu'au Rio Grande do Sul. Une cle d'identification pour les especes trouvees au Bresil est aussi presentee., Ce travail est le resultat d'une etude critique des stades de developpement de Cymothoa liannae (Isopoda, Cymothoidae), espece nouvelle ici decrite. Ce nouveaux cymothoadien a ete trouve sur la cote sud-ouest du Bresil, du Parana jusqu'au Rio Grande do Sul. Une cle d'identification pour les especes trouvees au Bresil est aussi presentee.]

POSTMARSUPIAL DEVELOPMENT AND GROWTH OF PAGURAPSEUDES LARGOENSIS MCSWEENY (CRUSTACEA, TANAIDACEA)

Postmarsupial development of the gastropod shell-inhabiting tanaidacean Pagurapseudes largoensis McSweeny is described and compared with that of Heterotanais oerstedii (Kr0yer) and Neotanais micromopher Gardiner. This is the first such study of an apseudomorphan based on experimentally reared animals. P. largoensis is gonochoristic; two manca instars are typical of all tanaidaceans so far investigated. In females, the mancas are followed by two or possibly three juvenile instars (=neutra), one or two preparatory instars characterized by rudimentary oostegites, and a copulatory stage with complete marsupium. Laboratory maintained animals pass through up to three copulatory stages, each separated by a preparatory stage of one or two instars. A preparatory instar, characterized by very small rudimentary oostegites often restricted to thoracopods VI, sometimes occurs between the juvenile and normal preparatory stages. The small number of such field-collected specimens suggests that it is an abnormality. Males develop either directly from the manca 2 instar or from the first juvenile instar. Pleopods and heterochelae either accompany initial appearance of genital cones or appear after one or two additional molts. Males retain a full set of mouthparts, feed, and molt throughout their lives. Variability in the pattern of instar succession may be construed as a primitive trait and supports the position of the Apseudomorpha as least derived of the three tanaidacean suborders. Males alone are heterochelous; the right chela is always major and its growth is allometric with respect to carapace length. Intermolt period increases with age, from a 2-week mean for mancas 1 to about 4 weeks for preparatory and copulatory females and 7 weeks for large males, although minimum intermolt periods are similar for all stages (11-29 days). Longevity is estimated at up to 15 months for males and 9 months for females. The sex ratio for field-collected specimens is about 1:1. Females bear 4-17 offspring per marsupium. Investigations into the development of the Tanaidacea have treated a very small percentage of the several hundred known species. Most are reconstructions of life histories based on preserved material. Biickle-Ramirez' (1965) experimental rearing of the tanaidomorph Heterotanais oerstedii (Kroyer) is the only detailed work based on live animals. The current investigation represents the first study of postmarsupial development of a member of the suborder Apseudomorpha to be based on live animals as well as preserved material. Pagurapseudes largoensis McSweeny, 1982, belongs to the family Pagurapseudidae Lang, 1970 (see also Gutu, 1972) and occupies vacant gastropod shells as do hermit crabs. It dwells in a variety of shallow, inshore, bottom communities in the Florida Keys but appears to prefer carpets of algae dominated by the red alga Laurencia poitei (Lamouroux) that occur in beds of turtle grass (Thalassia testudinum Konig). It is also frequently found clinging to the undersides of tussocks of the calcareous red alga Jania rubens (Linnaeus) and to bases of colonies of the inshore finger coral Porites divaricata Lesueur, both of which are found in Thalassia beds (Messing, 1979). This tanaidacean has both advantages and disadvantages as an experimental animal. It does not swim and can be kept in open dishes without becoming inextricably and fatally caught in the surface tension, a problem with tanaidaceans that can swim. It appears to be an unspecialized detritivore and is easily maintained in the laboratory. On the other hand, it occupies opaque or, at best, translucent shells that do not permit monitoring of ovarian maturation, egg deposition,

The systematics, postmarsupial development, and ecology of the deep-sea family Neotanaidae (Crustacea: Tanaidacea)

The systematics, postmarsupial development, and ecology of the deep-sea family Neotanaidae (Crustacea: Tanaidacea)

New species of the genera Synapseudes and Cyclopoapseudes with notes on morphological variation, postmarsupial development, and phylogenetic relationships within the family Metapseudidae (Crustacea: Tanaidacea)

In addition to the characters cited in the original description of the Metapseudidae the genera of this family share the presence of mandibular molar setae; a low level of sexual dimorphism; and the presence of oostegites on pereopods 1I-V only, all oostegites participating in the formation of the marsupium. The family can no longer be considered to be a strictly warm-water taxon; one species is now known from the southern tip of South America. Metapseudes and Synapseudes are most closely related, and both show considerable affinity with Apseudomorpha; Cyclopoapseudes is appreciably different morphologically and stands apart phylogenetically from these taxa. Metapseudes aucklandiae, the single species of the type genus, is discussed; a lectotype is designated; and additional information and figures are added to the original description. A new species of Synapseudes is described; the variable structure of the pleon in this morphologically aberrant genus is reviewed; and pleopods, found primarily among the males, are reported for Synapseudes for the first time; these resemble the reduced pleopods of Metapseudes and Apseudomorpha. Chelae of unequal size, known for several species of Synapseudes and formerly thought to be restricted to males, also occur in females. The postmarsupial development of Synapseudes is partially elucidated; the sexes are recognizable from very early stages, and there is no clear evidence for protogyny or protandry. A second species of Cyclopoapseudes is described in detail; exopods are present on pereopods I and II in this genus, contrary to previous information.