Asymmetric larval head and mandibles of Hydrophilus acuminatus (Insecta: Coleoptera, Hydrophilidae): Fine structure and embryonic development.

The larvae of a water scavenger beetle, Hydrophilus acuminatus, have strongly asymmetric mandibles; the right one is long and slender, whereas the left one is short and stout. The fine structure and embryonic development of the head capsule and mandibles of this species were examined using light and scanning electron microscopy, and asymmetries in shape were detected in these structures applying an elliptic Fourier analysis. The larval mandibles are asymmetric in the following aspects: whole length, the number, structure and arrangement of retinacula (inner teeth), and size and shape of both the molar and incisor regions.

Embryonic development of Carabus insulicola (Insecta, Coleoptera, Carabidae) with special reference to external morphology and tangible evidence for the subcoxal theory.

The egg morphology and successive changes in the developing embryos of the carabid ground beetle Carabus insulicola (Carabidae) are described based on light and scanning electron microscopy observations. Newly laid eggs of this species are ellipsoid and measure approximately 6.1 × 2.

Embryonic development of a whirligig beetle, Dineutus mellyi, with special reference to external morphology (insecta: Coleoptera, Gyrinidae).

The egg morphology and successive changes of developing embryos of the whirligig beetle, Dineutus mellyi (Adephaga: Gyrinidae) are described from observations based on light and scanning electron microscopy. The egg surface is characterized by minute conical projections covering the entire egg surface, a stalk-like micropylar projection at the anterior pole of the egg, and a longitudinal split line along which the chorion is cleaved during the middle embryonic stages. The germ band or embryo is formed on the ventral egg surface, and develops on the surface throughout the egg period; thus, the egg is a superficial type, as is the case in most coleopteran species.

Embryogenesis of the glowworm Rhagophthalmus ohbai Wittmer (Insecta: Coleoptera, Rhagophthalmidae), with emphasis on the germ rudiment formation.

The early embryonic development and features of the developing embryo of the glowworm Rhagophthalmus ohbai are described chiefly by light microscopy, with emphasis on the germ rudiment formation and its phylogenetic implication. The egg period is 30-34 days at about 23 degrees C. The newly laid egg is a short ellipsoid, 1.

Early embryonic development and external features of developing embryos of the caddisfly, Nemotaulius admorsus (trichoptera: Limnephilidae).

Formative processes of the blastoderm, germ disk, embryonic membranes, and germ band in the trichopteran Nemotaulius admorsus are described. Successive external changes of developing embryos are also described, chiefly on the basis of SEM data. The blastoderm is very thin, and a circular germ disk forms in its ventro-posterior region about 32 hr after oviposition.

Mesodermal organogenesis in the embryo of the primitive moth, Neomicropteryx nipponensis Issiki (Lepidoptera, Micropterygidae).

The formation of somites, coelomic sacs, splanchnic mesoderm, fat bodies, circular system, gonads, and musculature in the embryo of the primitive moth, Neomicropteryx nipponensis Issiki, is described. The following paired somites are formed: the labral, antennal, intercalary, mandibular, maxillary, labial, three thoracic, and 11 abdominal. Small but distinct coelomic cavities appear in all these somites.

Embryonic development of the alimentary canal and ectodermal derivatives in the primitive moth, Neomicropteryx nipponensis issiki (Lepidoptera, Micropterygidae).

The formation of the alimentary canal, nervous system, and of other ectodermal derivatives in the embryo of the primitive moth, Neomicropteryx nipponensis Issiki, is described. The stomodaeum is formed from an invagination in the medioposterior portion of the protocephalon. The proctodaeum arises as an extension of the amnioproctodaeal cavity.

The early embryonic development of the primitive moth, Neomicropteryx nipponensis lssiki (lepidoptera, micropterygidae).

This paper describes the early embryonic development of Neomicropteryx nipponensis from oviposition to the formation of the inner layer. Newly laid eggs are covered with many hygroscopic, gelatinous masses. The chorion is composed of a porous, spongy exochorion of variable thickness and of a thin endochorion.

The embryonic development of the primitive moth, Neomicropteryx nipponensis Issiki (lepidoptera, micropterygidae): Morphogenesis of the embryo by external observation.

The micropterygid moth Neomicropteryx nipponensis belongs to the most primitive suborder Zeugloptera of the Lepidoptera. During embryogenesis the small circular germ disk formed on the ventral egg surface invaginates deeply into the yolk. It finally separates from the egg periphery or rudimentary serosa, and becomes a sac-shaped germ rudiment.