Agnetina den, a new species of perlid stonefly (Plecoptera: Perlidae) from Vietnam

A new species of perlid stonefly, Agnetina den, is described from Vietnam. Male adults of this species can be easily distinguished by their black body color pattern, submedian patches of sensilla basiconica on hemitergites 7–8, and clusters of long dense fine setae on the inner sides the abdominal tergites. Illustrations of habitat and diagnostic characters are presented.     

Perlesta ephelida, a new Nearctic stonefly species (Plecoptera, Perlidae)

A new Nearctic species of Perlidae (Insecta, Plecoptera), Perlesta ephelidasp. n., is described from the male, female, and egg stages. This species has been previously reported as, or confused with, Perlesta shubuta Stark from several central and eastern U.S. states. Perlesta ephelida is distinctive from Perlesta shubuta and other regional Nearctic congeners mainly according to male genitalic and egg characteristics. Perlesta ephelida is a widely-distributed eastern Nearctic species, whereas Perlesta shubuta appears to be restricted to a narrow latitudinal belt in the Gulf Coast region from Louisiana east conservatively to the Florida panhandle. The egg of Perlesta shubuta is depicted with scanning electron microscopy for the first time.     

The life cycle of Pteronarcys scotti (Plecoptera: Pteronarcyidae) from the Southern appalachians,U.S.A.

Larval and adult Pteronarcys scotti Ricker were collected from a mountain stream in northwestern South Carolina, USA. The pattern of larval growth indicated a semivoltine life cycle. Emergence occurred in April and early May, and small larvae first appeared in May. Sexual dimorphism in adult size was apparent; males were 0.8 as large as females in head capsule width.

Female larvae possess a midventral notch on the eighth abdominal segment that can be used to sex larvae as small as 2.5 mm in head width. Female larvae as small as 1 mm in head width have a midventral break in the posterior setal row of segment 8. These characters are illustrated.     

Genetic evidence for `leaky' cohorts in the semivoltine stonefly Peltoperla tarteri (Plecoptera: Peltoperlidae)

1. Genetic techniques are being used increasingly to address questions about dispersal and gene flow of freshwater invertebrates. However, population genetic structure can be affected by factors other than dispersal. Many stream insects have long life cycles that result in the simultaneous existence of multiple cohorts throughout the larval development period. If larval development is fixed, successive cohorts may be reproductively isolated and, as a result, genetically distinct. In such cases, significant levels of genetic differentiation between cohorts could confound estimates of dispersal based on population genetic structure.
2.  Peltoperla tarteri is a stonefly that can be abundant in Appalachian headwater streams. Although P. tarteri is univoltine at the type locality (Big Paint Hollow, WV, U.S.A.), the study populations in southwestern Virginia, U.S.A., were semivoltine. This semivoltine life cycle results in the simultaneous existence of multiple cohorts with the potential for significant genetic differentiation among them.
3. Levels of genetic differentiation among P. tarteri cohorts were analysed with mitochondrial DNA (mtDNA) sequence data from the non-coding origin of replication or `control' region from 93 individuals from two successive cohorts (collected in 1998 and 1999).
4. Analysis of molecular variance ( AMOVA ) indicated no genetic differentiation among cohorts ( F _ST=0.0), and gene flow among cohorts was very high ( Nm =∞).
5. High levels of gene flow among cohorts suggest that larval development of P. tarteri is not fixed. Gene flow among cohorts most likely occurs as a result of a cohort split in which some individuals complete development in one or three years instead of two.     

Two new species of the stonefly genus Amphinemura (Insecta,Plecoptera, Nemouridae) from China

Two new species of the genus Amphinemura Ris from China are described and illustrated, i.e. A. annulata Du & Ji, sp. n. from Zhejiang, Shanxi, Shaanxi and Guizhou Province, and A. lingulata Du & Wang, sp. n. from Shaanxi and Sichuan Province. A. annulata is similar to A. tricintusidens Wang & Zhu in having an apical cavity of the epiproct, but the epiproct ventral sclerite and the median paraproct lobe of the two species are different. A. lingulata is related to A. didyma Zhu & Yang in having the similar epiproct, but they differ mostly in paraproct median and outer lobes.     

Female answer specificity to male drumming calls in three closely related species of the stonefly genus Zwicknia(Plecoptera:Capniidae)

This study examines the rate of female answers to conspecific versus heterospecific male vibratory calls in three,closely related stonefly species:Zwicknia bifrons,Z.acuta,and Z.rupprechti.In a previous study those three species were recognized on the basis of their distinct male drumming calls along with differences in genital morphology and genetic divergence.During this study no-choice playback experiments using original male call samples from each species were performed,and the answer rate of females to con?specific and heterospecific signal variants was measured.Mixed effect logistic regression models were used to test if male call species identity had a statistically significant effect on female answer probability.Females answered conspecific male calls with significantly higher probability than heterospecific calls in all the three examined species,suggesting that the divergence of vibrational communication can be an important component of the prezygotic isolation between them.Low,but well detectable responsiveness to heterospecific calls was observable between Z.bifrons and Z.acuta,the two species closest to each other regarding mitochondrial genetic divergence and male call pattern similarity.Thus,our results are most congruent with a tight,gradual coevolution of male calls and female preferences.     

A wingless alpine stonefly from New Zealand,and further information on genus Holcoperla (Plecoptera: Gripopterygidae)

Abstract

Holcoperla magna n.sp. is described and figured from material collected on Headlong Peak, Mt Aspiring National Park. New information is given on H. angularis (Wisely) and H. jacksoni McLellan, and the 3 species are compared. Larvae designated as type specimens of H. angularis are shown to be Apteryoperla monticola Wisely.     

A New Synonymy in the Genus Pteronarcys (Plecoptera: Pteronarcyidae)

Pteronarcys macra Ra, Baik et Cho, 1991 from South Korea is a new junior synonym of P. sachalina Klapálek, 1908. P. sachalina is frequently sympatric with P. reticulata Burmeister, 1839, and new characters to distinguish the larvae of both species are presented.     

Description of the vibrational duet of Besdolus ravizzarum Zwick & Weinzierl, 1995 (Plecoptera: Perlodidae)

Summary

The drumming of Besdolus ravizzarum is studied and analyzed for the first time. The male signal is diphasic with duration of approximately 350 to 400 ms and with interknock intervals decreasing in duration in both phases, while that of the female consists of a single knock. The male’s signal is much more complex than those reported for two other species of the genus Besdolus.     

Notes on the genus Agnetina (= Phasganophora) (Plecoptera: Perlidae)

Genus Agnetina Klapálek, 1907 is removed from synonymy with Dinocras Klapálek, 1907 and synonymy between Agnetina and Phasganophora Klapálek, 1914 is established. A list of presently recognised nominal species of Agnetina is provided. For all west palaearctic species, i.e., A. elegantula (Klapálek), A. senilis Klapálek, A. werneri (Kempny), comb, n., lectotypes are designated. Distinctive characters of these three species are described, external male genitalia and eggs are illustrated. Asian A. brevipennis (Navás), comb, n., is briefly compared. A. dubia nom. n. is proposed to replace A. brevipennis Klapálek, 1921 (not Navás, 1912), a doubtful Asian species. A. pedata (Koponen, 1949) and A. undaata (Klapálek, 1921) are considered possible synonyms of A. senilis. which is for the first time recorded from Central Asia (Baikal area).     

New species and records of the stonefly genus Neoperla (Plecoptera,Perlidae) from Jinhuacha Nature Reserve,Guangxi of China

Two new Neoperla species (Neoperla mesospina, Neoperla latispina) are described from the adult male stage from the Jinhuacha Nature Reserve, Guangxi of China. The new species are compared with similar taxa. Taxonomic remarks are also provided for N. transversprojecta Du & Sivec and N. yao Stark. The latter species is newly recorded for Guangxi.     

Development and ultrastructure of the thickened serosa and serosal cuticle formed beneath the embryo in the stonefly Scopura montana Maruyama, 1987 (Insecta,Plecoptera, Scopuridae)

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.     

Alimentary canal formation in the stonefly,Kamimuria tibialis (pictet) (Plecoptera : Perlidae)

The alimentary canal formation in the stonefly, Kamimuria tibialis (Plecoptera : Perlidae) is described. The stomodaeum is formed as in other insect embryos. The proctodaeum is derived from the ectodermal fold an the caudal end of the embryo without the contribution of the amnion. The 3 Malpighian tubules develop from the blind end of the proctodaeum. The rectal pad is formed by the thickening of the dorsal wall of the proctodaeum. The midgut epithelium rudiment arises only from the blind end of the proctodaeum, i.e. it is completed by unipolar formation instead of bipolar. The yolk cells do not contribute to the formation of the midgut epithelium. The alimentary canal is transformed during the 1st nymphal instar and becomes functional in the next instar. The stomodaeum is differentiated into 3 parts: pharynx, oesophagus, and proventriculus. The midgut becomes shortened and its epithelium is well developed. Gastric caeca with tapering processes are formed.     

贵州钩(虫责)属一新种记述((襀)翅目:(虫责)科)

记述采自贵州宽阔水保护区的钩(虫责)属l新种:巨刺钩(虫责)Kamimuria grandispinata Du ＆Sun,sp.nov.,该新种的阳茎特征与长刺钩虫责K.longispina Wu相似,但长刺钩(虫责)阳茎囊背面近端部有1膜质突起,上面生有粒状微刺,而新种阳茎囊背面近端部是1个近似三角形的刺斑,无突起...     

A revision of the Oriental stonefly genus Phanoperla (Plecoptera: Perlidae)

The genus Phanoperla (=Dyaperla Banks, 1939) (Plecoptera: Perlidae: Perlini) is revised and generic diagnoses are provided for adults and larvae. Diagnostic and constitutive characters of the tribe Neoperlini are discussed, and Chinoperla Zwick, 1980, is shown to be the closest relative of Phanoperla. Many past misidentifications of Phanoperla species have been corrected by the use of characters recently recognized as important, namely the structure of the internal genitalia of male and female specimens and particularly the complex pattern of spines on the male penial sac made visible by eversion of this structure, and details of sculpturing of the egg chorion.
The following species of Phanoperla are recognized: amorpha sp.n.; anomala (Banks, 1939); bakeri (Banks, 1924); ceylonica Kawai, 1975; comuta sp.n.; flaveola (Klapálek, 1921), comb.n. ( =clarissa (Banks, 1913), syn.n.), (=Neoperla hageni Banks, 1920, syn.n.), (= N.consimilis Banks, 1924, syn.n.); guttata sp.n.; himalayana Zwick, 1977 (= siwalika Harper, 1977); limosa (Hagen, 1858); maculata sp.n.; maindroni (Navas, 1926), comb.n.; malayana sp.n.; minutissima (Enderlein, 1909); nana sp.n.; nervosa Banks, 1939; nuwara Kawai, 1975; omega sp.n.; pallipennis (Banks, 1938); parva sp.n.; pumilio (Klapálek, 1921), comb.n.; peniculus Kawai, 1969a; schmidi sp.n.; sertispina Jewett, 1975; srilanka sp.n.; sumatrae sp.n.; testacea (Hagen, 1858); wedda sp.n. P.claggi (Banks, 1938) is a nomen nudum.
All species are (re-)described and figured; all primary types have been examined. A key to species is provided. Most species can be assigned to one of seven species groups which are defined.
Phanoperla is endemic to the Oriental Region. Species groups are generally widespread, but individual species are in most cases known only from restricted areas.     

Plecoptera response to acidification in several headwater streams in the Vosges Mountains (northeastern France)

Plecoptera are among the most threatened aquatic invertebrates in industrialised countries as they are very sensitive to many types of pollution. On the contrary, stoneflies are largely considered as tolerant to acidification in comparison with many other macroinvertebrate groups. However, an understanding of Plecoptera responses to acidification is lacking due firstly to the complexity of most Nemouroidea specific determinations at larval instars and secondly to the poor Plecoptera diversity in North European countries, where most studies on acidification impact were performed. In the present study, we assess the response of Plecoptera species and species assemblages to freshwater acidification by collecting adults, allowing specific determination. Significant relationships were observed between richness and several chemical parameters. The relative abundance of several species was also significantly correlated to pH and acid neutralizing capacity (ANC). The results highlight the importance of species determination to assess the effects of acidification. Direct effects, i.e. ecotoxicological effects, were not the only factor leading to the erosion of Plecoptera diversity. Finally, this study tends to demonstrate that this order of aquatic insects is more severely affected by freshwater acidification than commonly believed.     

Molecular systematics,evolution and zoogeography of the stonefly genus Siphonoperla (Insecta: Plecoptera,Chloroperlidae)

The stonefly genus Siphonoperla Zwick, 1967 (Chloroperlidae) ranges from the Atlas Mountains of North Africa, throughout Europe and east to the Lesser Caucasus Mountains in Armenia. Systematic relationships within the genus are unknown. We provide the first molecular phylogenetic reconstruction of the genus, based on sequence variation of 1348 bp of the mitochondrial cytochrome c oxidase subunit I gene and relate this phylogeny to a few key morphological features as well as zoogeographical perspectives. A total of 15 taxa (32 individuals), including four outgroup species (Chloroperla Newman, 1836 and Xanthoperla Zwick, 1967 ) were screened. Monophyly of Siphonoperla, as well as each purported taxon was supported, with net pairwise distances ranging from 0.7% to 13.7%. Within‐taxon variability ranged from 0% to 6.2%, whereby the upper value relates to Siphonoperla torrentium Pictet, 1841 represented in our sample by three allopatric subspecific taxa. These taxa, displayed as a polytomy with an estimated time to the most recent common ancestor of about 5.4 Myr, are also shown to have distinct genitalia. These data could be used to support a species‐level distinction for the three subspecific taxa. Siphonoperla ranged from 13% (Xanthoperla) to 16.2% (Chloroperla) divergent from the outgroup genera. The recently described Siphonoperla ottomoogi, Graf, 2008 from Austria is not closely related to the sympatric Siphonoperla montana Pictet, 1841 and is a minimum of 7.8% divergent from congenerics, supporting its status as a micro‐endemic relict surviving on the edge of Alpine glaciation throughout the Pleistocene. Overall, the genus shows the highest levels of diversification in the Mediterranean and Southeast regions whereby at least some of the species found in Central Europe today may have persisted there in peri‐glacial refugia throughout the Pleistocene.     

Life cycle and nymphal feeding of Besdolus ravizzarum (Plecoptera: Perlodidae), a threatened stonefly

Abstract We have studied some aspects of Besdolus ravizzarum biology in the Apennines. This stonefly has a very localized distribution in southeastern France and northern Italy. This species is considered threatened. For this reason it is especially relevant to improve knowledge about its natural history, previously unknown. Despite the large size of nymphs, this species shows a univoltine life cycle. The growth is slow but uniform from October to April or May when the short flight period occurs. The analysis of the gut contents indicates this species is a predator, feeding mainly on Baetidae and Chironomidae. It is notable that the development of this carnivorous species through cold periods coincides with the season with higher richness and density of potential prey in Apennine streams. Further studies are needed to improve knowledge of the distribution of the species and to start planning effective conservation efforts.