Size composition, growth and sexual maturity of Callinectes latimanus (Rath.) in two Ghanaian lagoons

Blue crabs Callinectes latimanus (Rath.) trapped from two lagoons were sexed, measured and weighed. The eggs of the mature females were counted to determine fecundity, and the spermatophores of the males were counted to determine the size of sexual maturity. Sizes at maturity of both male and female crabs were determined. The methods employed and the results are discussed.     

Mating status regulates post‐mating refractory period in Striacosta albicosta females

In polyandrous insect species, males may transfer substances to reduce sperm competition by affecting female sexual receptivity. In this study, we determined the incidence of polyandry in females of Western bean cutworm (WBC), Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), and investigated the influence of both previous female and male mating history on the duration of mating, the female refractory period, and subsequent calling behavior of females under controlled laboratory conditions. The mating status of WBC males influenced mating duration, with copulations involving previously mated males taking longer, possibly related to the time required to produce an ejaculate. The duration of the female refractory period and the onset time of recalling during the scotophase were both affected by female mating history, but not by that of the males. Females had a shorter refractory period and resumed calling activity earlier after their second and third matings than after their first mating. The earlier onset of calling by previously mated females could reduce competition with virgin females and their shorter refractory period could explain the high incidence of polyandry observed in nature.     

An extraordinary new carnivorous sponge,Chondrocladia lyra,in the new subgenus Symmetrocladia (Demospongiae,Cladorhizidae), from off of northern California,USA

Chondrocladia (Symmetrocladia) lyra subgen. nov., sp. nov., is described from northeast Pacific sites at Escanaba Ridge and Monterey Canyon at depths of 3316–3399 m. Two retrieved specimens are described in detail, while variations are described in ten photographed or videotaped specimens. The basic structure, termed a vane, is harp‐ or lyre‐shaped. From 1 to 6 vanes extend by radial growth from the organism's center. The orientation among the vanes is approximately equiangular, such that together they display pentaradiate, tetraradiate, triradiate, or biradiate symmetries. Each vane is formed by a horizontal stolon supporting a series of upright, equidistantly spaced branches each of which terminates at its apex in a swollen ball in all observed specimens except the paratype. Swellings occur midway along the branches in the holotype, but not in the paratype. A linear row of filaments project from the sides, front, and back of each branch, and also from the tops of each stolon. The terminal balls are the sites of spermatophore production and release; mid‐branch swellings are sites of oocyte maturation. The two megasclere spicule types have specific distributions; styles support rhizoids, stolons, and branches, while subtylostyles support filaments and terminal balls. Anchorate isochelae cover all surfaces. Enclosed crustacean prey on branches and stolons provide direct evidence of carnivory. The structure of the vanes maximizes surface area for passive suspension feeding. Increased surface area could also maximize spermatophore capture, with the sigmas projecting from the spermatophore surface being caught by projecting isochelae on filaments. Swellings on filaments are snared spermatophores, firmly fused to recipient tissues and undergoing destruction. Spermatophores on filaments are present in branch swellings containing early and mature oocytes. Oogenesis and maturation occur only in proximity to branch swellings, suggesting that development is induced by spermatophore reception. Symmetrical development of uniserial branched stolons (the vanes) characterized members of the new subgenus Symmetrocladia.     

Paternity Analysis in a Hexapod (Orchesella cincta; Collembola) with Indirect Sperm Transfer

In species where males and females interact during mating, the role of females in sexual selection cannot always be demonstrated unambiguously. Here we present a model system to study female choice for mates. Orchesella cinca is a soil-dwelling hexapod with indirect sperm transfer. Females and males do not interact physically for reproduction. We gave females the choice between spermatophores produced by two different males. Paternity analysis based on microsatellite variation revealed that offspring in one clutch were sired by one male only. Direct observations showed that after a female has taken up a spermatophore, the female's receptivity to further spermatophore uptake seem to end. Our results imply that the female is in full control of paternity.     

Distant Lovers: Spermatophore Deposition and Destruction Behavior by Male Springtails

Males of the springtail Orchesella cincta transfer their sperm indirectly using spermatophores. The present study aimed to investigate how individual males maximize their reproductive success. In an experiment examining the role of chemical communication, it appeared that the males deposit their spermatophores preferentially on patches which have been conditioned with conspecifics. Varying conditioning intensity resulted in a response which can be described by a saturation curve. In a comparison involving a related species the conditioning effect was strictly species specific. An experiment where the sexes were compared showed that conditioning with males exerts a slightly stronger effect than conditioning with females. In another experiment spermatophore depositing males showed a strong preference for patches with spermatophores of previous males, which they replaced with their own. An explanation for this may be that the males parasitize each other's scent marks. When a number of males are kept together they destroy most of each other's spermatophores. The destruction behavior is specifically displayed by males in their reproductive phase. Video recordings showed that deliberate destruction of spermatophores takes place by eating them and that the males are able to recognize and spare their own spermatophores.     

The year cycle of Eudiaptomus vulgaris (Schmeil, 1896) (Copepoda,Calanoida) in a small,acid water body during 1973. Development in the natural habitat and relationships between temperature and duration of development stages

The development of a population of Eudiaptomus vulgaris (Schmeil, 1896) in the Meeuwenven, a shallow acid guanotrofic moorland pool, has been described during one year. The population hibernates as copepodite 5 stages, adults and, to a small extent as naupliar stages N1, N2 and N3 (which could not develop further at low temperatures in autumn). In spring the population development starts at temperatures above 10°C and shows 3 or 4 pulses a year. An attempt has been made to explain seasonal changes in the size of adult males and females and in the sex ratio.In order to establish the duration of the various development stages, the animals have been cultured at different temperatures under illumination with 2000 Lux at a daylength of 14 hours. An adequate quantity of food from the natural habitat was available.Total egg development and total naupliar and copepodite development have been compared with the results of other workers, especially with those from Eckstein (1964), who studied Eudiaptomus vulgaris in the deep Schluchsee. The duration curves do not differ markedly with those of Eckstein and are strongly temperature dependent.The relation between the development times of the various stages with temperature can be generally expressed as parabolic regressions of the type D = a + b₁T + b₂T², the C₅ and adult stages being the only exception at higher temperatures. Comparison of the relative duration of the stages at different temperatures did show that younger stages can take a larger share of the total development time at lower temperatures, stage N6 being the most temperature-sensitive.     

Mating and spermatophore morphology of water mites (Acari: Parasitengona)

In this paper I synthesize original and published studies of sperm transfer behaviour of 23 genera of water mites from 15 families. The morphology of spermatophores from 16 genera (12 families) is described. Behaviour and/or spermatophores are described for the first time for the following species: Hydrachna magniscutata Marshall, Hydrachna hesperia Lundblad, Hydrachna sp. nr. leegei Koenike, Limnochares americana Lundblad, Limnesia undulata (Müller), Neumania distincta Marshall, Unionicola (three species in the U. crassipes-complex), Thyas slolli Koenike, Lebertia annae Habeeb, Lebertia sp., Piona sp. nr. debilis (Wolcott), Tiphys vernalis (Habeeb), Arrenurus dentipetiolatus Marshall, Arrenurus marshalli Piersig and Arrenurus birgei Marshall. On the basis of proximity of male and female during sperm transfer, I divide water mites into four groups: complete dissociation, involving no physical or chemical contact between the sexes (nine genera); incomplete dissociation, requiring distance-or contact-chemoreception but not involving pairing behaviour (five genera); pairing with indirect transfer, involving pairing behaviour with females controlling sperm uptake (three genera); pairing with direct transfer (=copulation), involving pairing behaviour and male placement of sperm in the receiving structure of the female (12 genera). Four genera have representative species in more than one category of sperm transfer. Factors possibly leading to the diversity of water mite mating behaviour include an evolutionarily flexible mode of sperm transfer in the ancestral water mite, and the development of planktonic and endoparasitic habits in many mites. Morphological features of spermatophores that improve physical stability, probability of females taking up sperm and resistance against osmotic stress are discussed. Finally, I present implications of mating behaviour and spermatophore morphology for phylogenetic relationships within water mites and between this group and terrestrial Acari.     

Functional morphology of the reproductive system of Galathea intermedia (Decapoda: Anomura)

Spermatophore formation in Galathea intermedia begins in the proximal part of the vas deferens. The contents subsequently form a spermatophoric ribbon, the so-called "secondary spermatophore," in its distal part. A strongly muscular ductus ejaculatorius is present in the coxa of the fifth pereiopod which builds up pressure for the extrusion of the spermatophoric ribbon. After extrusion, the ribbon is caught by the first gonopod, while the second gonopod dissolves the matrix of the ribbon. During copulation the spermatophores are randomly placed on the sternum of the female, near the genital opening, by the fifth pereiopods of the male. Subsequent ovulation of the female via the genital opening, an active process accomplished through muscular activity, results in fertilization of the eggs by the exploding spermatophores. External intersexes are characterized by both male and female external sexual characters, but in all individuals only male gonads are present. No trace of a female reproductive system could be detected. Thus, these external intersexes are exclusively functional males.     

The influence of male ejaculate quantity on female fitness: a meta‐analysis

Although the primary function of mating is gamete transfer, male ejaculates contain numerous other substances that are produced by accessory glands and transferred to females during mating. Studies with several model organisms have shown that these substances can exert diverse behavioural and physiological effects on females, including altered longevity and reproductive output, yet a comprehensive synthesis across taxa is lacking. Here we use a meta‐analytic approach to synthesize quantitatively extensive experimental work examining how male ejaculate quantity affects different components of female fitness. We summarize effect sizes for female fecundity (partial and lifetime) and longevity from 84 studies conducted on 70 arthropod species that yielded a total of 130 comparisons of female fecundity and 61 comparisons of female longevity. In response to greater amounts of ejaculate, arthropod females demonstrate enhanced fecundity (both partial and lifetime) but reduced longevity, particularly for Diptera and Lepidoptera. Across taxa, multiply mated females show particularly large fecundity increases compared to singly mated females, indicating that single matings do not maximize female fitness. This fecundity increase is balanced by a slight negative effect on lifespan, with females that received more ejaculate through polyandrous matings showing greater reductions in lifespan compared with females that have mated repeatedly with the same male. We found no significant effect size differences for either female fecundity or longevity between taxa that transfer sperm packaged into spermatophores compared to taxa that transfer ejaculates containing free sperm. Furthermore, females that received relatively larger or more spermatophores demonstrated greater lifetime fecundity, indicating that these seminal nuptial gifts provide females with a net fitness benefit. These results contribute to our understanding of the evolutionary origin and maintenance of non‐sperm ejaculate components, and provide insight into female mate choice and optimal mating patterns.