Embryogenesis of Dinocras cephalotes, Perla grandis and P. marginata (Plecoptera: Perlidae) in different temperature regimes

1. Temperature dependence of embryogenesis of the three perlid stoneflies Dinocras cephalots , Perla grandis and P. marginata was investigated by means of incubation experiments. Special emphasis was laid on the effect of fluctuating temperatures and on intraspecific differences between populations from two different field sites in the Swiss prealps (i.e. River Necker and River Thur).
2. Dinocras cephalotes embryos develop between 6.3 and 26.6 °C. The lower threshold temperature is lower than has been reported for more northern populations (i.e. from England and Norway), indicating the existence of a latitudinal gradient. Perla grandis eggs only developed between 9.9 and 18.4 °C. In P. marginata , successful embryogenesis was observed between 9.9 and 18.4 °C, but not enough eggs were available to explore the threshold temperatures.
3. Embryogenesis of D. cephalotes and P. grandis was significantly faster at a 12/16 °C daily fluctuating temperature regime than at a constant 14 °C. However, no significant difference was found between the development under simulated field temperature regimes (with less distinct daily amplitudes) and constant temperatures.
4. D. cephalotes , hatching of eggs from the Necker population was much less synchronous than that in the Thur population. Since the Necker discharge regime is harsher than the Thur regime, it is possible that this asynchrony spreads the risk of destruction during bed-moving floods.     

Comparative proteomic analysis of hemocyanins in Dinocras cephalotes and Perla marginata (Plecoptera)

Hemocyanins are large oligomeric respiratory proteins found in many arthropods and mollusks. The overall expression of hemocyanin mRNA, revealed by studies on Plecoptera hemocyanin sequencing, has raised the question of whether the protein is expressed or not. In fact, the presence of expressed hemocyanin has only been reported in the literature for one species, Perla marginata (Panzer, 1799). In this paper, we report the presence of hemocyanin and hexamerin proteins in Dinocras cephalotes (Curtis, 1827), a species closely related to P. marginata. To assess the presence of hemocyanin, we used a reproducible and highly sensitive method based on liquid chromatography tandem mass spectrometry. We conclude that regardless of its putative function (respiratory, immune defense, storage protein), the hemocyanin is actually expressed in species in which its mRNA is present.     

Ultrastructural and histochemical studies of the egg capsules of Perla marginata (Panzer, 1799) and Dinocras cephalotes (Curtis, 1827) (Plecoptera : Perlidae)

Eggshells of stone flies P. marginata and D. cephalotes (Plecoptera : Perlidae), inhabiting mountain streams, were examined using scanning and transmission electron microscopes, a phase-contrast light microscope and histochemical methods to detect proteins, lipids and polysaccharides.The eggshells of the species investigated consist of a vitelline envelope, chorion and gelatinous sheet decorated on its outer surface with mushroom-like structures. An anchoring structure (attachment disc) is situated on the posterior pole of the egg. The structure and function of the attachment disc, as well as the possible taxonomic applications, are discussed. The morphology and histochemical composition of all these elements of the shell clearly demonstrate good adaptation to land and aquatic habitats; the chorion consists of 2 layers, the internal layer being finely perforated by numerous aeropyles. The external layer, with fewer, regularly placed aeropyles, protects the egg interior against dehydration in the land habitat. The gelatinous sheet seems to provide additional protection. Mushroom-like structures, situated on its surface, correspond with the positions of aeropylar openings. These and other interrelations between chorion structure and function are discussed.     

Feeding of Perla grandis nymphs (Plecoptera: Perlidae) in an Apennine first order stream (Rio Berga,NW Italy)

Feeding habits of Perla grandis (Rambur) nymphs have been investigated in the Rio Berga, an Apenninic stream of Northwestern Italy. In this study, we analysed gut contents of 50 nymphs of this species, with the aim to investigate feeding preferences. Nymphs were collected from a single riffle, of which benthic coenosis was also determined. We detected a change in the diet during ontogenesis, with small instars feeding mainly on detritus and large instars strictly carnivorous. We also detected the existence of an evident trophic selection: diet was almost entirely dominated by Chironomidae, independently from their availability on the substratum. This finding is discussed on the basis of ecological and ethological considerations.     

Nymphal feeding habits of Perla madritensis Rambur 1842 (Plecoptera: Perlidae)

The diet of Perla madritensis, endemic species of the northern half of the Iberian Peninsula, is described for the first time by means of a study carried out in north-western Spain. As other species of the genus Perla, this taxon behaves mainly as predator, with Chironomidae, followed by Baetidae, being the most abundant prey in its gut. Shifts in diet composition were detected in relation to size in this species, with smaller prey being replaced by larger ones such as Simuliidae and Leptophlebiidae when the nymphs become larger.     

Variable egg development of Dinocras spp. (Plecoptera, Perlidae) and the stonefly seed bank theory

1. Temperature dependence of egg development of Dinocras cephalotes (Curtis) (three German and one Norwegian population) and Slovenian D. megacephala (Klapálek) was studied under a constant 14 : 10 light : dark photoperiod and constant temperature ranges of 4–24 °C and 4–18 °C, respectively. D. cephalotes was also incubated under seasonal field conditions; natural daylength and fluctuating temperatures had no modifying effect. 2. Both species have very similar lower threshold temperatures (4 and 3.5 °C, respectively), thermal demand for development (c. 600 degree days) and high dependence of mean incubation period on temperature (exponents of regressions near 1.5). Present data on D. cephalotes agree with the literature on British and Norwegian material of the same species. 3. Development occurs only at cue temperatures above the lower threshold. Cue temperatures range from 6 °C (some D. megacephala) to 14 °C (some D. cephalotes) and vary strongly within and between egg masses of D. cephalotes. Variation is not random, but seems to be genetically determined. 4. The variable temperature response renders study of effects of particular experimental regimes, and comparisons between local populations, difficult. 5. A latitudinal gradient in cue temperatures for development from 6 °C at c. 46 °N to 12 or even 14 °C at c. 61 °N seems to reflect reduced diversity at high latitudes. 6. Average success of spontaneous hatching exceeded 90% between 12 and 20 °C, but declined towards higher and lower temperatures. 7. Unhatched eggs were not dead but in parapause; development at other, higher or lower, temperatures was induced. Spontaneous plus induced hatching success approached 90%. Developing eggs rarely died; most dead eggs were apparently unfertilized. 8. Dormant plecopteran eggs are proposed to form a seed bank in stream bed sediments. Highly successful development after up to 220 days of dormancy was ascertained in Dinocras, and survival for up to 3 years is reported for other Perloidea. 9. Only systellognathan egg morphology provides options for long dormancy; the other plecopteran superfamilies, notably Nemouroidea, follow different strategies.     

Life cycle,nymphal feeding and secondary production of Dinocras cephalotes (Plecoptera) in a Mediterranean river

Summary. Some aspects of the life history of a population of Dinocras cephalotes inhabiting a Mediterranean river in Southern Spain were studied over a year (2012–2013). The life cycle of this population seems to be semivoltine, of approximately two years of duration, and with an asynchronous egg hatching period. The comparison of these data with those of an unpublished study carried out in the same population almost a decade before (2004–2005) shows the existence of no differences between years. The nymphal feeding study revealed that the main prey of these organisms are Chironomidae, Psychomyiidae and Baetidae, but some of them, usually the smallest, also had non-animal matter in their guts, mainly detritus, coarse particulate organic matter and algae. So, an onthogenetic shift in feeding was detected. This feeding confirms broadly what was already reported in previous studies in the same and other populations. Finally, and for the first time for this species, the secondary production was estimated. Due to differences in hatching, and so development, among nymphs, annual secondary production was calculated both assuming a CPI of 20 months and a CPI of 14 months. In both cases this value was relatively high, 2854.46 and 4077.80 mg DW m^–2 year^–1, respectively. These results were compared with those of other predators, and particularly with a stonefly predator with a similar life cycle and from a nearby temporal river.     

Descriptions of oriental Perlini (Plecoptera: Perlidae)

Three new species of Oriental Perlini are described and Agnetina aequalis (Banks) and A. quadrituberculata (Wu) are redescribed. Agnetina jarai sp. n. (Vietnam), Togoperla shan sp. n. (Thailand), and Tyloperla schmidi sp. n. (Assam), are described, compared with related congeners, and male holotypes are designated for each species.     

Notes on Plecoptera (23). The Anchor of the Tetropina Egg (Plecoptera: Perlidae)

After a study of the type material of Baetis nexus Navás, 1918 and a comparison with Hungarian specimens of Baetis pentaphlebodes Ujhelyi, 1966 it is concluded that the two nominal species are synonyms and that B. nexus is the valid name.     

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...     

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.     

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).     

Notes on Perlesta (Plecoptera: Perlidae) from Eastern North America

The identity of Perlesta nitida is reviewed and demonstrated to be a valid species. The male is redescribed with an emphasis on internal genitalia, and the egg stage is described for the first time. Morphological features distinguishing P. nitida from similar species are provided. New distributional records of additional Perlesta species are reported.     

Adult feeding habits of three Perloidea species (Plecoptera: Perlidae and Chloroperlidae)

The gut content composition of three species of the superfamily Perloidea, Marthamea selysii (Pictet, 1842), Dinocras cephalotes (Curtis, 1827), and Siphonoperla torrentium (Pictet, 1842), from northwestern Spain is analyzed and described. The quantity of food found in all adults of M. selysii and D. cephalotes was very low. Spores of fungi and pollen of angiosperms were the most abundant components in the diet of M. selysii. Pollen of angiosperms, followed by fungal spores, detritus, and animal matter were the most abundant components in the diet of both sexes of D. cephalotes. The adult diet of both sexes of S. torrentium consists mainly of pollen and agrees with data of the previous studies on this same species in other areas. Our results also show that the consumption of animal matter could be a way to get a nutritional complement and is more common than previously considered in adult stoneflies. The obtained data support the hypothesis that adult feeding is less important for large stoneflies (as M. selysii and D. cephalotes) than for other smaller Perloidea (as S. torrentium), but feeding habits in these large Plecoptera could not be as negligible as previously supposed.     

Two new species in the subfamily Perlinae (Plecoptera,Perlidae) from China

Two species in the genera Neoperla and Kamimuria (Plecoptera: Perlidae) from China are described as new: Kamimuria guangxia sp. n., and Neoperla mesostyla sp. n. The new species are compared to similar taxa.     

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.