The larval development of Petalomera japonica (Henderson) (Decapoda,Dromiidae) reared in the laboratory

The complete larval development of Petalomera japonica (Henderson) is described, based on laboratory rearing. The species has two zoeal stages and a megalopa. Detailed comparisons are made with other dromiid larvae, particularly those of Petalomera wilsoni.     

Larval development of the fiddler shrimp,Metapenaeopsis stridulans (Alcock, 1905) (Decapoda: Penaeidae) reared in the laboratory

Larvae of Metapenaeopsis stridulans (Alcock, 1905) from Malaysia were successfully reared in the laboratory from the egg to the 1st post-larval stage. The larvae developed through six naupliar, three protozoeal and four mysis stages. The morphology of all these larval stages is described and figured.     

Larval development of the coronuloid barnacles Austrobalanus imperator (Darwin), Tetraclitella purpurascens (Wood) and Tesseropora rosea (Krauss) (Cirripedia,Tetraclitidae)

The presence of embryos in the mantle cavity of A. imperator, T. purpurascens and T. rosea was monitored over two years. Tesseropora rosea showed a clearly defined breeding season in summer and early autumn. Seasonal breeding in A. imperator and T. purpurascens was less well defined, a small number of gravid individuals being present during most of the year. Breeding increased during the late autumn and early winter in A. imperator and during winter, spring and early summer in T. purpurascens. The larval stages of A. imperator, T. purpurascens and T. rosea are described from larvae reared in the laboratory. Separation of the larval stages between these species depends on fine morphological detail. Distinctive larval features permit the separation of coronuloid larvae from those of the other balanomorph superfamilies, but coronuloid nauplii resemble balanoid nauplii more than chthamaloid nauplii.     

The complete larval development of the crab Pilumnus spinifer (Brachyura: Xanthoidea: Pilumnidae) reared in the laboratory

The complete larval development of the crab Pilumnus spinifer from the western Mediterranean was obtained in the laboratory. All four zoeal stages and the megalopa are described and illustrated. The morphological characters of the larvae of Pilumnus spinifer are compared with those of other known larvae of the genus. The zoeae of P. spinifer show the rostral spine longer than the antennule (excluding aesthetascs); short lateral spines present on the carapace, and the mediolateral processes are present only in abdominal somites 2 and 3. The megalopa is similar to that of other Pilumnidae species. The morphology of the larval stages shows very similar characteristics to that of those of P. hirtellus and P. dasypodus, among the described stages of the family.     

Larval development of the circular crab,Atelecyclus rotundatus (Olivi) (Crustacea: Brachyura: Atelecyclidae) reared in the laboratory

The complete larval development is described of laboratory-reared Atelecyclus rotundatus and the stages are compared with larvae of other cancrideans (= corystoideans). The results suggest that the subfamily Atelecyclinae requires reappraising and that present larval evidence does not support the currently accepted grouping of families in the Cancridea.     

Pherbina mediterranea: immature stages,biology, phenology and distribution (Diptera: Sciomyzidae)

The egg, three larval instars, and puparium of Pherbina mediterranea are described. The duration of the various immature stages indicates that this specis is univoltine and spends the winter as quiescent larvae. The biology, phenology and geographical distribution are presented. The main features of the larvae are illustrated with scanning electron micrographs. A key to the adults of genus Pherbina is given.     

The larval and post-larval development of Gibbs's spider crab,Pisa armata (Latreille) [family Majidae: subfamily Pisinae], reared in the laboratory

Summary

The larvae and first crab stage of the spider crab Pisa armata are described from laboratory reared material. The larval stages are compared with previous accounts and with those of Pisa tetraodon. Larval affinities with other genera of Pisinae are discussed.     

Morphology and larval development of Polydora cf. websteri (Polychaeta: Spionidae) in a tropical region of north-eastern Brazil

Polydora websteri belongs to a group of the Spionidae known as the Polydora complex, members of which are known for building tubes within the shells of mussels and for their ability to infest commercially valuable bivalves, which causes serious losses for malacoculture. P. websteri is a species subjected to increasing research due to the global scale at which these infestations occur. In this paper, we describe the larval development of P.cf. websteri associated with the oyster Crassostrea cf. brasiliana in a tropical region of north-east Brazil. The main structures of all stages of development were analysed and compared to other populations of P. websteri. Ovigerous capsules of P.cf. websteri were cultured in the laboratory and the larval stages were analysed until metamorphosis. Ovigerous capsules were present in all sampling intervals, indicating that this population exhibits continuous reproduction. Up to 21 capsules per tube were found, and the number of eggs per capsule varied from 20 to 40. All observed eggs developed into larvae. Larval development from egg to recruitment stage did not exceed 13 days. Metamorphosis occurred when larvae attained 17 chaetigers, at which stage important diagnostic characteristics were revealed, such as the spines on chaetiger 5. The developmental stages of P.cf. websteri larvae, and the morphological features found at each stage, are in accordance with what has been recorded for temperate populations. In our study, the planktonic stage was found to be of shorter duration than elsewhere, which might be associated with the higher temperatures at which larvae were cultured compared to previous studies.     

Larval development in Phimochirus roseus (Benedict) (Decapoda: Anomura: Paguridae) reared in the laboratory

The zoeal and megalopal stages of Phimochirus roseus (Benedict, 1892) are described and illustrated from material reared under laboratory conditions. Although the vast majority of zoeae of this species pass through only four larval stages before the moult to megalopa, an occasional fifth stage has been observed. Phimochirus roseus differs in a number of morphological attributes from the only other species of Phimochirus whose larvae have been described. However, their shared features are sufficiently characteristic to confirm the distinctiveness of the genus and its general developmental homogeneity.     

A comparative study of the larval development of Monodaeus couchi (Couch), Xantho incisus Leach and Pilumnus hirtellus (Linnaeus) (Crustacea: Brachyura: Xanthidae)

Summary

Comparative accounts are given of the larval and first crab stages of three crab species belonging to the family Xanthidae: Monodaeus couchi (Couch), Xantho incisus Leach and Pilumnus hirtellus (Linnaeus). Features are discussed that distinguish the larvae of these species from those of other N.E. Atlantic brachyrhynch crabs.     

Observations on courtship,mating and sexual maturity in Portunus pelagicus (L., 1766) (Crustacea,Portunidae)

Summary

Larvae of Alpheus heterochaelis from North Carolina hatch from large eggs as advanced zoeae, usually moult three times, and exhibit almost no linear growth during a short (4 days at 25°c) larval development. Stage I lasts 6 hours at most and is sometimes skipped; III lasts about twice as long as II. Individuals simultaneously exhibiting characteristics of Stage III and the postlarva were occasionally seen. The three zoeal stages and postlarva are described in detail and illustrated. Stages in embryonic and juvenile development and the hatching process are briefly described.

An ‘extended’ pattern of larval development, characteristic of most alpheid species, is described in a general way, and the ‘abbreviated’ development of A. heterochaelis compared to it. At hatching, A. heterochaelis larvae bear rudimentary pereiopods and pleopods; other structures are at the same level of development in both patterns, but subsequent morphogenesis is faster in A. heterochaelis. Larval development of Synalpheus spp., some of which exhibit extreme abbreviation or direct development, is briefly described with reference to the A. heterochaelis pattern.     

Bionomics,behaviour and immature stages of Pelecotoma fennica (Paykull) (Coleoptera: Rhipiphoridae)

Ptilinus fuscus (Anobiidae) was confirmed as the host species of Pelecotoma fennica (Rhipiphoridae, Pelecotominae). Females of Pelecotoma oviposit into the wood infested by the host larvae. First-instar larvae are elongate, unsclerotized, very different from the triungulinid larvae known in other rhipiphorids. They search actively for the host larvae in the wood; no phoresy is involved in the life cycle. The first-instar larvae temporarily paralyse the host larva and enter its body, overwintering (some perhaps more than once) as an endoparasite. In the spring of the year of emergence, the endoparasite engorges enormously (without moulting) and develops a special sclerotized caudal structure which is then used for perforation of the host's integument. The larva undergoes a further four ectoparasitic instars. The fifth (i.e. fourth ectoparasitic) instar differs considerably from the preceding three, and is capable of boring through the wood to prepare the emergence gallery for the adult. Pupation occurs in the wood. The rate of parasitization may locally far exceed 50%. Superparasitization by the first-instar larvae is possible, but usually only 1 larva survives to the ectoparasitic stage. Larval morphology of Pelecotoma is described and illustrated. Additional data on bionomics and larval morphology are also presented for the genus Metoecus (Rhipiphorinae). Comparing the biology and larval morphology of Pelecotoma with other Rhipiphoridae, it is assumed that ancestral rhipiphorids may have been xylophilous Tenebrionoidea with predaceous or omnivorous larvae, and that the ‘triungulinid’ larvae and phoretic habits may not belong to the groundplan of the family Rhipiphoridae. The widespread opinion considering Rhipiphoridae closely related to the family Mordellidae is questioned.     

Larvae of Homola (Crustacea; Dromiacea) from South Africa

Summary

Five zoeal stages of probably a single Homola species from the S.E. Atlantic are described. There are six zoeal stages in this species, of which the first is lacking from the present series. The zoeae probably belong to Homola barbata Fabr., linking the stages previously described by Pike and Williamson (1960) and by Rice (1964), giving a good idea of the complete larval development of this genus. Anomalies in the published work, however, point to the existence of taxonomic problems not previously apparent from studies on the adults alone.

The absence of exopods from the legs of these larvae adds further support to the contention that the grouping of the Dromiidae and Homolidae together in the Dromiacea is artificial.