The larval development of Argulus coregoni Thorell (Crustacea: Branchiura)

Summary

The larval development of Argulus coregoni from the first to the ninth stage was studied, with special reference to the morphological changes of the appendages and some other parts of the body.

A newly hatched larva is a copepodid-form measuring 0·6–0·7 mm long and approaches the shape of the adult after moulting into the second stage (0·7–0·9 mm). Throughout the larval stages, the first maxilla shows the most remarkable modification. The larvae of the first to the fifth stage are equipped with two strong, curved claws, which act as a clasping organ, at the terminal segment of the first maxilla. The basal segment expands considerably at the third stage (0·9–1·1 mm) prior to forming a sucker at the sixth stage (1·7–2·2 mm). The claws start to degenerate at the fifth stage (1·4–1·8 mm), but are still recognizable as a rudiment after the seventh stage (2·2–2·6 mm). The other distinct morphological changes that occurred are: (1) bifurcation of the anterior part of the dorsal ridges on the carapace, (2) development of the male accessory copulatory organ at the basal segments of the second to the fourth legs, (3) number of posteriorly directed minute spines on the ventral surface of the carapace, (4) number of elements in the supporting ribs of the suckers, (5) number of spines found at the first segment of the second maxilla, and (6) number of setae on the four pairs of thoracic legs.

The larval forms of A. coregoni younger than the fourth stage (1·1–1·4 mm) are indistinguishable from those of A. japonicus and A. foliaceus.     

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.     

Polygyny,oviposition, life cycle and longevity of the three subspecies of leaf-cutting ants,Acromyrmex subterraneus (Hymenoptera: Formicidae)

ABSTRACT

Research related to the comparative biology of phylogenetically close ant species has received little attention, although it is the basis for understanding the systematics of some sibling groups. The objective was to study the polygyny, oviposition, life cycle and longevity of the three subspecies of leaf-cutting ants. For that, we studied: oviposition rate – queens from three colonies were individually placed in plastic containers, and at 24-hour intervals, the laid eggs were quantified over a period of 96 hours; the workers’ life cycle – the development of immature ants was observed every 24 hours and, as a result, the duration of each stage of development was determined; the workers’ longevity – newly emerged adults were tagged and returned to the fungus chamber of their respective nests, and daily observations were made in each of the nest’s chamber. Laying rates were variable in the three queens studied, with a mean of total eggs laid of 271 for Acromyrmex subterraneus brunneus, 113 for Acromyrmex subterraneus subterraneus and 119 for Acromyrmex subterraneus molestans.The incubation period was 21.2 days in A. s. brunneus, 22.8 days in A. s. subterraneus and 20.4 days in A. s. molestans. The larval phase and pupal phase lasted on average 22.5 and 21.2 days in A. s. brunneus, 22.8 and 15.8 days in A. s. subterraneus and 17.2 and 14.2 days in A. s. molestans, respectively. Life cycle was different in the studied taxa, from 62 to 77 days in A. s. brunneus, from 59–68 days in A. s. subterraneus and from 51 to 55 days in A. s. molestans. The workers’ longevity varied between subspecies A. s. brunneus, A. s. subterraneus and A. s. molestans.     

Copepodid stages of laboratory-reared Astericola asterinae (Bocquet, 1952) (Copepoda,Poecilostomatoida, Lichomolgidae), a copepod associated with Asterina gibbosa (Pennant, 1777) of Lake Faro (Messina)

We describe the five copepodids of Astericola asterinae (Bocquet, 1952) a poecilostomatoid copepod (family Lichomolgidae), reared in the laboratory. It shows only very slight sexual dimorphism in the third segment of C5 maxilliped. Our study of the copepodid development, together with the observations of Carton (1964), Bocquet et al. (1970) and Conradi et al. (1993), support the separation of A. asterinae from its sister species A. clausi (Rosoll, 1889).     

The life-history of Anoplocnemis curvipes F. (Coreinea,Coreidae, Heteroptera) A pest of fresh cowpea pods

Summary

Facts are given on the preoviposition and oviposition of mated females of A. curvipes. The size, shape, colour, incubation and hatching of eggs are described. The morphology and development of neanides at various stages are described—and compared with some data on the egg and neanide periods of a related species A. phasiana. Differences are pointed out between the neanides and adults of A. curvipes and the longevity and sex ratio of the adults are discussed.     

A biosystematic study of Aspidiotus nerii Bouché (Homoptera: Diaspididae), with the description of one new species

Summary

Uniparental (UP) and biparental (BP) populations of the oleander or ivy scale, Aspidiotus nerii Bouchè, were reared under similar conditions. Development of the UP population was always slower than that of the BP scales. UP females usually produced less than half the number of progeny the BP females had, and the patterns of development and oviposition were quite dissimilar.

The shield of UP females was slightly, but consistently, darker than that of BP females, and the latter never colonized Pittosporum undulation, the only host-plant on which UP population occur in Israel. These criteria are used to describe the uniparental population as Aspidiotus paranerii Gerson sp. nov. and to differentiate it from A. nerii. As the biology of A. paranerii clearly differs from that of a Californian uniparental sibling species of A. nerii, it is argued that the latter may have a series of such parthenogenetic relatives.     

Larval development of Pandalus gracilis Stimpson (Crustacea: Decapoda: Pandalidae) reared in the laboratory

The complete larval development of Pandalus gracilis Stimpson is described based on larvae reared in the laboratory. The species has four larval stages (stages 1–4) and one postlarval stage (stage 5). The survival rate of the postlarva stage is very high. Of the 40 larvae reared individually, 39 larvae moulted to the postlarva stage within approximately 21 days at a rearing temperature of 15°C. Larval morphological characteristics of the species are described and figured. Larval development of P. gracilis is compared with other Pandalus and Pandalopsis species. Komai (1999 Komai, T. 1999. A revision of the genus Pandalus (Crustacea: Decapoda: Caridea: Pandalidae).. Journal of Natural History, 33: 1256–1372.  [Google Scholar]) divided species of Pandalus into four species groups based on adult morphology. Pandalus gracilis belongs to the P. hypsinotus group. In this study, using larval characters, the P. hypsinotus group can be divided into two groups by the appearance of the mandibular palp and the shape of the telson: the first group contains P. hypsinotus and P. danae, and the second group contains P. gracilis, P. prensor, and P. nipponensis.     

Notes on the natural history of Stizus perrisii ibericus Beaumont (Hymenoptera: Sphecidae)

A study of the biology of Stizus perrisii ibericus revealed some aspects about the behaviour of males, the nesting behaviour of females, and larval development. The slow mass provisioning of this species is compared with the provisioning behaviour of S. continuus and S. pulcherrimus. Cocoons are constructed in seven stages although, compared with other species, there are differences in the duration of each stage. Natural enemies of the wasp include miltogrammine flies, several cuckoo wasps, and velvet ants.     

Notes on astogeny of some Petraliellidae (Bryozoa) from Australia

Members of the bryozoan family Petraliellidae share the capacity to develop basal rhizoids, which anchor the unilaminar, semi-repent parts of the colonies above the substratum, and enable them to overgrow other, competing sessile forms. Little is known of the larval behaviour and settlement, or the early astogeny of species. Ancestrulate colonies of the Australian Tertiary lunulitiform species Smittia biincisa are referred to the genus Riscodopa, and together with Riscodopa paucipora sp. nov. are described and compared with the Recent species R. cotyla and R. parva from New Zealand, and with R. hyalina sp. nov. from New South Wales, Australia. All the Recent species are known to develop basal rhizoids, and an early astogeny similar to that of many other small, rooted bryozoans, comprising the post-metamorphosis development of a binary complex, including rhizoid and feeding elements, is inferred for Riscodopa. Observations on living Hippopetraliella magna from Queensland suggest that both the ancestrular morphology and early astogeny show a capacity for semi-repent growth, even though they do not include rhizoid development. Larvae metamorphose without direct attachment, and the ancestrula develops elongated, partially calcified supporting processes, which raise the early stages of growth above the substratum. A similar kind of ancestrula has been found in preserved specimens of Mucropetraliella ellerii.     

The cytogenetics of Lotus (Leguminosae)

Chromosome numbers for 108 species of the genus Lotus (Leguminosae) are now known. This represents an increase of 32 new species which have been reported since a chromosome atlas for Lotus was published in 1965. At this rate, with just over one chromosome number being reported for a new species per year, it will require almost a century for the chromosome numbers to be determined for all of the species in the genus. A review of the cytogenetic features which have been observed in the genus through karyotype analyses, chromosome banding, Feulgen cytophotometry, anther culture, HCN reaction and interspecific hybridization is presented. These include cytomixis and B chromosomes (both found in hybrids of diploid species in the L. corniculatus group when L. alpinus was one of the parents), desynapsis, binucleate cell formation, polytene chromosomes in suspensor cells and trisomics in L. pedunculatus. There has been a reduction of HCN content in the species with evolutionary development which is correlated with basic chromosome number and geographic distribution. Classical karyotype analyses may not be a suitable method to investigate the parentage of L. corniculatus because of the chromosomal repatterning which has occurred during the evolutionary development of the closely related diploid species.     

A new species of Halolaelapidae (Acari: Mesostigmata: Rhodacaroidea) from beach wrack in Yaquina Bay,Oregon, USA,with comments on opisthonotal plasticity and cribral development in the family

Decomposing beach wrack in a backwater of Yaquina Bay, Oregon, was found to contain nymphs and adults of a previously undescribed species of the mite genus Halolaelaps (Halolaelapidae). Significant variation was noted among available specimens in the number of opisthonotal shield setae, a feature that has long been considered to be of critical importance in identifying celticus group species. The presence of a well-formed posterodorsal cribrum in this and related celticus group species prompted an examination of cribral development in the Halolaelapidae as a whole and revealed that posterodorsal cribral elements occur in various configurations in three of the four presently recognized halolaelapid genera. A narrow, transversely oriented configuration appears to be unique to members of the celticus species group.     

Palaearctic species of Ammoplanus (Hymenoptera: Sphecidae)

The Palaearctic species of the genus Ammoplanus Giraud are revised, based on material of over 1750 specimens from Europe, North Africa and Central Asia. For almost all species it was possible to examine the type material and in six species the lectotypes have been designated, in two cases (A. perrisi and A. marathroicus) the neotypes. As a result 38 species are recognized as valid, keyed out and commented on. Eight species are described as new and four species names are here placed in synonymy. Several species are of wide distribution, which made it necessary to include also those described from Central Asia and Mongolia. The keys are made to all Palaearctic species but no material is known from the regions east of Mongolia, although four undescribed species are available from South-East Asia. The Afrotropical species are listed and most of them were also examined. Two subgenera are recognized in the region; 32 species are classified in Ammoplanus sensu stricto and six in the subgenus Ammoplanellus. In the nominal subgenus the following species are described as new: A. atlasensis from Morocco, A. biscopula from Israel, A. biskrensis from Algeria, A. denesi from Turkey (Anatolia), A. freidbergi and A. kaplanae from Israel, A. minutus from Bulgaria and Turkey and A. strumae from Bulgaria and Greece. New synonymy: A. angelae becomes a junior synonym of rhodesianus (known before only from Africa), A. crudelis a synonym of A. kaszabi, A. handlirschi a synonym of A. marathroicus, A. suarezi a synonym of A. kohlii, A. subcompressus of A. gegen, A. orbiculatus of A. simplex and A. zarcoi of A. kohlii; A. wesmaeli is confirmed as a synonym of A. perrisi. Otherwise the synonymy is corrected under A. bischoffi and the names A. dusmeti and A. curvidens are re-established as valid. In a short review of the African species A. (Ammoplanellus) cradockensis Arnold, 1959 is placed as a new synonym under A. (Ammoplanellus) latiscapus Leclercq, 1959. The nomenclatural changes are explained under the relevant species.     

Comparative investigation of the late embryogenesis of Leptodora kindtii (Focke, 1844) (Crustacea: Branchiopoda), with notes on types of embryonic development and larvae in Cladocera

The embryonic development of the parthenogenetic eggs of Leptodora kindtii has been investigated by observing living embryos removed from the female brood pouch. The sequence of morphological changes was analysed, as was the time at which the activity of certain organs began. The timing of these events at 20–22°C is documented. These data were compared with similar information obtained for some representatives of Ctenopoda and Anomopoda. The sequence of appearance of rudiments of organs on the ventral side of the embryos is similar in all these groups but the timing of shedding of the embryonic membranes differs. Hatching from the inner egg membranes takes place at the late metanauplius stage in Leptodora as in Ctenopoda and Cyclestherida, while in Anomopoda this stage is embryonized. The development of Leptodora is more like that of Ctenopoda than of Anomopoda. The embryos of all the above‐mentioned groups begin to grow at approximately the same morphological stage. A new scheme for the periodization of the embryogenesis of L. kindtii is proposed, which includes four well‐separated stages. Previously, the same number of developmental stages has been reported for Ctenopoda and Anomopoda. In Leptodora, as well as in Ctenopoda, the first two of these occur within the egg membranes. Cyclestheria has at least one embryonic moult and one embryonic stage more than Leptodora and other cladocerans. Embryonic stages 3 and 4 of the parthenogenetic eggs of L. kindtii represent a peculiar type of secondary larvae developing inside the female's brood pouch. The appearance of a free‐living nauplius in L. kindtii arises from its mode of hatching from the gamogenetic egg.     

Differing morphology and ultrastructure of the male copulatory apparatus in species-groups of Anagrus Haliday (Hymenoptera: Mymaridae)

Male genitalia of 13 members of the mymarid wasp genus Anagrus have been studied: Anagrus (Anagrella) mymaricornis (Bakkendorf), Anagrus (Paranagrus) unilinearis Soyka, A. (Anagrus) ustulatus Haliday, A. (A.) erythroneurae Trjapitzin and Chiappini, A. (A.) atomus (Linnaeus), A. (A.) aegyptiacus Soyka, A. (A.) vilis Donev, A. (A.) sensillatus Viggiani and Jesu, A. (A.) breviphragma Soyka, A. (A.) incarnatus Haliday, A. (A.) obscurus Förster sensu Soyka, A. (A.) fennicus Soyka and A. (A.) avalae Soyka. Taxonomically significant differences between subgenera and the atomus and incarnatus species-groups are described. The functional significance of various features, and in particular, the arrangment of sensilla are discussed.     

Population variation of web-invading spiders (Theridiidae: Argyrodes spp.) on host webs in Guam,Mariana Islands,Micronesia

Most Argyrodes spiders live in the webs of other spiders as kleptoparasites, stealing food from the host and scavenging small prey from the web. We observed three species of Argyrodes from the Micronesian island of Guam to learn (1) if Argyrodes species differ in their use of host-species webs, (2) whether some Argyrodes species occur more often in certain habitats, (3) whether population size of Argyrodes is a function of web size, and (4) how the presence of congeners affects population size on a web. Argyrodes lived most often in the large, long-lasting orb webs of Argiope appensa and Cyrtophora mollucensis, and, rarely, in the smaller, less durable orb webs of Neoscona spp. and Leucauge spp. Argyrodes argentatus and Argyrodes sp. A frequently co-occurred in Argiope webs, but A. argentatus was more common in beach strand and open disturbed habitats, while Argyrodes sp. A was more common in shaded native forest. The abundances of A. argentatus and Argyrodes sp. A in Argiope webs and the abundance of Argyrodes sp. B in Cyrtophora webs were positively correlated with the areas of the webs' prey-catching surfaces. The abundance of A. argentatus was inversely proportional to that of Argyrodes sp. A on Argiope webs and to that of Argyrodes sp. B on Cyrtophora webs, suggesting interspecific avoidance.     

Terrestrial isopods and myriapods in a forested scree slope: subterranean biodiversity,depth gradient and annual dynamics

Diversity, depth distribution and seasonal activity of isopods and myriapods were studied using subterranean traps buried in a forested limestone scree slope in the ?ierna Hora Mts, Western Carpathians, Slovakia, throughout the depth gradient from 5 to 95 cm. A total of five isopod, 13 diplopod and 11 chilopod species were identified. Most edaphic species strongly preferred the uppermost organic soil layers. Among the species captured, some represented rare stenoecous Carpathian endemics, namely the isopod Trichoniscus carpaticus, and diplopods Julus curvicornis and Leptoiulus mariae. Others were subterranean forms, partly adapted to hypogean conditions: the isopod Mesoniscus graniger, and diplopods Mecogonopodium carpathicum and Trachysphaera costata. The annual activity in the vast majority of the species ceased completely in winter, and was gradually relaunched in spring. In evaluating the age structure of two predominant diplopods Polydesmus denticulatus and Mecogonopodium carpathicum, both widespread across the depth gradient, a vertical segregation of early post-embryonic stages was found. While P. denticulatus tended to undergo the early stages of development in the soil-filled topmost levels, the early juvenile stage of M. carpathicum was distributed deep in the scree slope profile.     

African species of the mealybug genus Antonina Signoret (Hemiptera: Coccoidea: Pseudococcidae)

Four species of the legless mealybug genus Antonina have been recorded from Africa and are discussed here. These are A. graminis (Maskell), A. indica var. panica Hall, A. natalensis Brain and A. transvaalensis Brain. All are grass feeding species and live mainly at the base of the plants, between the leaf sheath or at the roots. The names A. indica var. panica and A. transvaalensis have been synonymized previously with A. natalensis but the three species are regarded here as distinct. A. indica var. panica is here raised to specific rank as A. panica. A. graminis is known world-wide, A. panica occurs in North Africa and extends into Israel and possibly Jordan, and A. natalensis and A. transvaalensis are known from the Afrotropical Region. All four species are redescribed and illustrated and a key is provided to aid identification.