Macrochelid mite fauna in the eastern part of the Lesser Sunda Islands, with description of two new species

Thirteen species in four genera of mites of the family Macrochelidae phoretic on dung beetles were collected in the eastern part of the Lesser Sunda Islands, Indonesia, providing the first record of the family for that area. Of these, two species, Macrocheles entetiensis Hartini and Takaku, sp. nov. and Macrocheles sumbaensis Hartini and Takaku, sp. nov., are new to science. The remaining 11 species are Glyptholaspis fimicola, Holostaspella bifoliata, Macrocheles baliensis, Macrocheles sp. aff. glaber, M. hallidayi, M. kraepelini, M. krantzi, M. limue, M. merdarius, M. oigru and Neopodocinum sinicum.     

Morphological difference and reproductive isolation: morphometries in the millipede Parafontaria tonominea and its allied forms

Thin-plate spline and other multivariate statistical methods were used to examine the variation in genital morphology and body size in 74 populations of the millipede Parafontaria tonominea and its allied forms in central Japan. Although the study populations included nine sympatric pairs of two reproductively isolated forms, the variations in genital morphology and body size observed were continuous across the study group. Analyses of the sympatric pairs using bootstrapping revealed that the degree of morphological difference between sympatric populations varied considerably from pair to pair. These results demonstrate that the degree of difference in genital morphology and body size may not correspond with the establishment of reproductive isolation. Significant correlation in the pattern of geographic variation was observed for many combinations of morphological components. However, it was not possible to detect a significant correlation between morphology and geographic distance in many of the morphological components studied. This study suggests that the incorporation of genital characters in classification should be done carefully, particularly for animal groups with low vagility, such as millipedes.     

Hormonal Control of Sexual Differentiation and Reproduction in Crustacea

SYNOPSIS. Sexual differentiation in malacostracan Crustaceais controlled by the androgenic gland hormone (AGH). In males,the primordial androgenic glands (AG) develop and AGH inducesmale morphogenesis. In females, the primordial AG does not developand the ovaries differentiate spontaneously. Implantation ofthe AG into females yields various results, showing that thesensitivity to AGH differs with the species and the receptiveorgans. Purified AGH of the isopod Armadillidium vulgare consistsof at least two molecular forms, which exist as monomeric proteinswith molecular weights of 17,000 ± 800 and 18,300 ±1,000 Da and with isoelectric points of about 4.5 and 4.3, respectively.The antiserum raised against purified AGH makes it possibleto measure AGH activity by immunoassay. Neurohormones control male and female reproduction. In males,they are involved in the maintenance of the male germinativezone and the control of AG activity. In females, the secondaryvitellogenesis is controlled by the vitellogenesis-inhibitinghormone (VIH) and the vitellogenesis- stimulating hormone (VSH).VIH isolated from the lobster Homarus americanus is a peptidewith a molecular weight of 9,135 Da and shows homology to thecrustacean hyperglycemic hormone and moltinhibiting hormone.Involvement of the molting hormone and the juvenile hormone-likecompound in the secondary vitellogenesis have also been suggested.In the amphipod Orchestia gammarella, the vitellogenesis- stimulatingovarian hormone (VSOH) seems to control vitellogenin synthesis     

Endocrine and genetic control of sex differentiation in the Malacostracan Crustacea

Summary

Sex differentiation in Malacostraca is controlled by hormone secreted from the androgenic glands. Experimentally induced sex inversions in isopods and amphipods proved that the genetic female and male possess primordia of the androgenic glands, gonads, and gonoducts, along with sexual characteristics of both sexes. During the sensitive period, the presence or absence of androgenic gland hormone (AGH) affects the differentiation of these primordia.

Genetic control of the development of androgenic gland primordium seems to be brought about assuming of the following: 1. Both genetic female and male possess gene(s) (AGH-G) responsible for the AGH-synthesis situated on the homologous loci of the sex chromosomes and/or on the autosomes. 2. The gene(s) are activated spontaneously with the lack of inhibition of the major sex factor carried by the W or X chromosome. The W and X factors are hypostatic to major sex factor carried by the Y chromosome. The Z factor does not seem to influence sex differentiation. Sufficient allochthonous AGH seems to render the W and X factors ineffective.     

ANDROGENIC GLAND HORMONE AND DEVELOPMENT OF OVIDUCTS IN THE ISOPOD CRUSTACEAN, ARMADILLIDIUM VULGARE

When androgenic glands from mature males were implanted into females of Armadillidium vulgare during the 3rd, 4th and 5th instars, oviducts developed in 14.3, 37.9 and 85.2% of the masculinized females, respectively. These results show that development of the rudimentary oviducts is inhibited by the androgenic gland hormone in very young females. Development of the oviduct seems to be determined at a critical period in about the 4th instar and after this, the hormone has little inhibitory effect.     

Geographical variation and diversification in the flightless leaf beetles of the Chrysolina angusticollis species complex (Chrysomelidae, Coleoptera) in northern Japan

Geographical variation and differentiation of flightless leaf beetles of the Chrysolina angusticollis species complex were analysed. Nine morphological groups were recognized on the basis of metric characters relating to body size, shape of hind wing and shape of male genitalia, and binary characters relating to females' elytral surface and larval pubescence. The nine groups were essentially parapatric or allopatric to each other. Five groups occupied a continuous geographical range each, whereas another four groups were disjunctively distributed. Morphometric distance and geographical distance between populations were significantly correlated. Analyses based on 13 allozyme loci demonstrated that six out of the nine morphological groups were further divided into more than one genetically distinct group each. Genetic similarity between populations was significantly correlated with morphometric similarity and geographical closeness. Disjunctively distributed populations of a single morphological group more often resembled geographically adjacent populations of different morphological groups than geographically remote populations of the same group. In a morphological group that occupied a wide continuous range, remote populations substantially differed genetically from each other. The results suggest that there exist at least 19 morphologically and/or genetically differentiated units in the C. angusticollis complex in northern Japan. The C. angusticollis complex is likely a superspecies composed of a number of semispecies. We postulate that the diversification of this species complex might have resulted from the repeated range contraction and expansion during the ice ages. Movement of tension zones that separate two adjacent forms might contribute to enhance their geographical differentiation.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 557–578.     

Distribution and host specificity of the thistle‐feeding tortoise beetle Cassida vibex (Coleoptera: Chrysomelidae) in southwestern Hokkaido,northern Japan

The thistle‐feeding tortoise beetle Cassida vibex (Coleoptera: Chrysomelidae) is widespread in the Palearctic region. In Japan, this species has been recorded only from the largest island, Honshu. Here we report the occurrence of this species on Hokkaido, the most northern main island of Japan, along with detailed distributional records from the southwestern part of the island (southern Oshima Peninsula) and information on host plants. We also present the results of laboratory experiments on adult feeding preference and larval developmental performance to determine the specificity of C. vibex for four thistle species (Cirsium grayanum, Cir. alpicola, Cir. yezoense and Cir. aomorense; Asteraceae) common in southwestern Hokkaido. Cassida vibex was detected at only four sites among 97 sites investigated on the Oshima Peninsula, in strong contrast to the common occurrence of the congeneric thistle feeder C. rubiginosa (74 of 97 sites). Cassida vibex was found mainly on Cir. alpicola in the wild, but adult beetles showed no feeding preference for this or three other thistle species when given a choice in the laboratory. Larval performance of C. vibex was similar on Cir. alpicola, Cir. yezoense and Cir. aomorense but significantly lower on Cir. grayanum. Since Cir. alpicola often forms large clumps of individual plants, whereas Cir. yezoense and Cir. aomorense are scattered in their habitats, and C. vibex was collected only at sites where there were dense patches of Cir. alpicola, we postulate that the persistence of C. vibex is possible only where a substantial amount of suitable host plants is available.     

Morphological Characterization of Three Phenotypes of the Isopod Armadillidium vulgare

The morphological characteristics and ommochrome quantity in the integument of red, white, and wild type (black-grey) Armadillidium vulgare were studied. The red phenotype was found to possess two kinds of immature ommochrome pigment granules within its pigment cells, in addition to mature pigment granules. The immature granules seemed to contain uniformly distributed fibrilles, or to have an electron-dense central region surrounded by an electron-lucent outer edge. Since these immature pigment granules were typically observed to be distributed along with the mature ones, and were also more easily extractable than the wild type's, it is hypothesized that ommochrome granule maturation in the red phenotype may occur slowly due to a defect in the pigment granule internal process which combines pigments with matrix proteins. Regarding the white phenotype, although its pigment cells were undeveloped, several large-sized vesicles containing a small amount of electron-dense material appeared in the pigment cell cytoplasm. The wild and red type males of A. vulgare were found to have an ommochrome content twice as large as that of the corresponding females, with no ommochrome pigment being detected in the white phenotype. The genetic relationship between the white and red phenotypes was discussed using as a basis the observed pigment granule structure.     

Genetic and Biochemical Studies on Ommochrome Genesis in an Albino Strain of a Terrestrial Isopod,Armadillidium vulgare

Genetic studies and quantitative determination of levels of 3-hydroxykynurenine and kynurenine were performed in an albino strain of a terrestrial isopod Armadillidium vulgare. From the results of matings between the albino and the albino, the red, the dark red, or the wild type individuals, the albino A. vulgare seems to be regulated by an autosomal gene(s) recessive to its wild allele. Litter mating of F₁ progenies obtained by crossing the albino and the red mutant or the albino and the dark red mutant yielded progenies at a ratio of 3:6:3:4 for the red, the dark red, the wild, and the albino phenotypes, respectively. The albino gene(s) seems not to be allelic but to be epistatic to the red gene(s) with respect to ommochrome biosynthesis. Quantitative determination of 3-hydroxykynurenine carried out by high-performance liquid chromatography with electrochemical detection revealed that the 3-hydroxykynurenine content in the albino was significantly lower than that in the wild or the red type. The whole content of 3-hydroxykynurenine after enzymatic conversion of kynurenine to 3-hydroxykynurenine was still considerably lower than that found in the wild type, even though it increased after the conversion. The albino gene(s) seems to be associated with a blockage at distinct level(s) of ommochrome biosynthesis.