The first instar nymphs of two peltoperlid stoneflies, i.e.,
Microperla brevicauda
Kawai, 1958 of Microperlinae and
Yoraperla uenoi
(Kohno, 1946) of Peltoperlinae, were examined and described. ...Additionally, the phylogeny and groundplan of the first instar nymphs of Peltoperlidae and Plecoptera were considered. The first instar nymphs of
M. brevicauda
have a slender body with a prognathous head of typical shape; they represent a groundplan in Plecoptera. On the other hand, the first instar nymphs of
Y. uenoi
have a broad, cockroach-like body with an orthognathous and shortened head, the latter being regarded as a potential autapomorphy of Peltoperlinae. Such differences in body shape between the subfamilies are speculated to arise from heterochrony. The three-segmented cerci of
Y. uenoi
are characteristic to Systellognatha, whereas the four-segmented cerci of
M. brevicauda
were independently acquired within Microperlinae. The structure and distribution pattern of chloride cells in the first instar nymphs of Plecoptera were also discussed. The presence of coniform chloride cells is a potential groundplan of Arctoperlaria. One to two pairs of chloride cells are distributed on the first nine abdominal segments of
M. brevicauda
; this represents a groundplan character of Systellognatha. On the other hand, one to four pairs of chloride cells are found on the second to ninth abdominal segments of
Y. uenoi
; this distribution pattern may be an apomorphic groundplan of Peltoperlinae.
We aimed to describe the development and ultrastructure of the thickened serosa and serosal cuticle formed beneath the embryo of Plecoptera, using Scopura montana of Scopuridae as a euholognathan ...representative. Using transmission electron microscopy, we found that the egg membranes were composed of a thick exochorion, a thicker endochorion consisting of two sublayers, and an extremely thin vitelline membrane. The egg membrane construction represents a groundplan feature of the euholognathan egg membranes. The serosa converges beneath the embryo to form a thickened serosa, comprising cells in a radial arrangement, in association with the formation of the amnioserosal fold. The thickened serosa then deposits the thickened serosal cuticle, consisting of four layers differing in fine structure and electron density. After achieving its secretory function, the thickened serosa then disintegrates, and the liberated serosal cells float for a short period in the peripheral region of the egg inside. Collectively, our findings should provide the basis for further characterization of the serosal structures concerned, but we were unable to corroborate previous studies assigning the thickened serosa and serosal cuticle in Plecoptera to the water absorption function.
•Serosal derivatives beneath stonefly embryos were described for the first time.•The serosa converges beneath the embryo to form the thickened serosa.•The thickened serosa deposits a bulky four-layered cuticle beneath the embryo.•The thickened serosa that accomplished its secretory function soon disintegrates.
We report the distribution, infestation, and feeding plants of the alien longhorn beetle Apriona swainsoni swainsoni (Hope, 1840), recently discovered from Fukushima Prefecture, Japan, which is a ...serious pest of Styphnolobium japonicum in China. We found a specimen collected at Sukagawa City in 2014, suggesting that this species was introduced in Japan by 2014 at the latest. In some areas of Sukagawa and the adjacent Koriyama Cities, where A. swainsoni swainsoni has been found, S. japonicum and Maackia amurensis, which are planted as a roadside tree, especially the latter, have been infested by this alien species. Additionally, in captivity, we found that A. swainsoni swainsoni can eat two native Fabaceae species, Lespedeza bicolor and L. homoloba, which are widely distributed from hilly to montane areas in Japan. It is necessary to consider whether A. swainsoni swainsoni will be expand its distribution in Japan.
Zygentoma is an order of wingless insects, representing the sister group of Pterygota and constituting Dicondylia together with Pterygota. Contrasting views exist regarding midgut epithelium ...formation in Zygentoma. According to some reports, in Zygentoma, the midgut epithelium is entirely derived from yolk cells as in other wingless orders; however, according to other reports, the midgut epithelium is of dual origin in Zygentoma, similar to that in Palaeoptera of Pterygota, i.e., the anterior and posterior midgut epithelia are stomodaeal and proctodaeal respectively, whereas the middle part of the midgut originates from yolk cells. Aiming to provide a sound basis to evaluate the true image of midgut epithelium formation in Zygentoma, we examined the formation of the midgut epithelium in detail in Thermobia domestica, and concluded that the midgut epithelium is exclusively derived from yolk cells in Zygentoma, without the stomodaeal and proctodaeal elements involved in its formation. The participation of the anlagen differentiated at or around the stomodaeal and proctodaeal extremities in the formation of the midgut epithelium (bipolar formation) may be regarded as having first appeared not in Dicondylia but in Pterygota, of which the major part is represented by Neoptera with the midgut epithelium formed through bipolar formation.
•Development of midgut epithelium in Thermobia was examined in detail.•Midgut epithelium of Zygentoma is exclusively derived from yolk cells.•Stomodaeal and proctodaeal elements do not participate in midgut epithelium formation in Zygentoma.•Bipolar formation of midgut epithelium is a derived feature that first appeared in Pterygota.
The egg structures of five antarctoperlarian species – Stenoperla prasina of Eustheniidae; Austroperla cyrene of Austroperlidae; and Zelandobius truncus, Megaleptoperla grandis, and Acroperla ...trivacuata of Gripopterygidae, were examined in detail, and the groundplan of the egg structure was considered within the representative lineages of Antarctoperlaria and Plecoptera. The flattened egg shape and the circular arrangement of micropyles along the equator are regarded as potential autapomorphies for not only Eustheniidae but also for Eusthenioidea. Austroperlidae has eggs with thin, less-sclerotized chorion, a gelatinous layer on the surface, and micropyles roughly and randomly arranged along the equator. A significant ultrastructural difference between the attachment disc in Gripopterygidae and the anchor plate of arctoperlarian Systellognatha suggests that these structures were independently derived. The thin less-sclerotized chorion represents a groundplan feature in Plecoptera, along with micropyles arranged in a circle, including those circularly arranged along the equator of the egg. On the other hand, in contrast to previous understanding, the sclerotized hard chorion is regarded as a derived feature, having been independently acquired in each of Eustheniidae and Gripopterygidae of Antarctoperlaria and Systellognatha of Arctoperlaria.
•Egg structures of five Antarctoperlaria species were examined in detail.•Groundplan of egg structure in Antarctoperlaria and Plecoptera was discussed.•Antarctoperlarian attachment disc and arctoperlarian anchor plate were derived in parallel.•Not sclerotized chorion but thin less-sclerotized one represents a groundplan feature in Plecoptera.•Circular arrangement of micropyles is a groundplan feature of Plecoptera.
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