Stonefly Species Research Articles

Winter Stoneflies of Illinois (Insecta: Plecoptera)

Winter stoneflies (Insecta: Plecoptera) are an aquatic group of insects whose adults emerge in IIlinois from late November to early April. Twenty-one species have been reported from Illinois. Extensive collections of winter stoneflies were made in Illinois during the 1920s and 1930s by Frison, the 1960s by Ross and “the winter stonefly club’, and the 1990s by Webb. These specimens are housed in the Insect Collection of the Illinois Natural History Survey and allowed for an evaluation of the current status of these species following a century of environmental change.Over the past century (1900-2000), the species diversity of winter stoneflies averaged 2.5 species per county with species reported from every county but 3 (Carroll, DuPage, Ford) and with 10 counties recording 5 or more species. Pope County (13 species) reported the greatest species diversity. During the recent resurvey (1976-2000), species diversity average 1.9 species per county withspecimens not collected in 11 counties, and only 3 counties (Hardin, Pope, and Saline) exhibited 5 or more species.Four species are considered extirpated from Illinois: Allocapnia illinoensis, Nemocapnia carolina, Paracapnia angulata, and Taeniopteryx parvula. Seven species were found to be common (known from more than 15 localities): Allocapnia forbesi, A. granulata, A. mystica, A. rickeri, A. vivipara, Taeniopteryx burksi, and T: nivalis. Four species are considered uncommon (known from 4—15localities): Allocapnia recta, Strophopteryx fasciata, Taeniopteryx metequi and Zealeuctra claasseni. Six species are considered rare (known from 1-3 localities): Allocapnia nivicola, A. smithi, Prostoia completa, Taeniopteryx lita, Zealeuctra fraxina, and Z. narfi. Significantly reduced patterns of distribution were noted in three species: A. granulata, A. mystica, and Strophopteryx fasciata. OnlyTaeniopteryx nivalis, previously rare, is now spreading its distribution across northern Illinois.There has been a modest decline during the past century in the diversity of stonefly species within various counties. Also, a trend was observed toward an increase in pollution-tolerant, “generalist” species with a decrease in pollution-sensitive, habitat “specialists.”

Perla carantana - a new species of the genus Perla (Plecoptera: Perlidae) from Austria and Slovenia

Members of the genus Perla are the largest, and amongst the most endangered European stonefly species. During a revisionary study of this genus, a new species was discovered at several localities in Austria and Slovenia; Perla carantana was named after Carantania, a 7th - 11th century political unit within the territories of Austria and Slovenia. Adults and larvae are nearly indistinguishable from the sympatric species, Perla burmeisteriana Claassen, but the two species can be clearly distinguished on the basis of egg chorion morphology.

Descriptions and Records of Anacroneuria from Venezuela (Plecoptera: Perlidae)

Two new stonefly species, Anacroneuria segnini Stark and Maldonado sp. n. and A. cacute Stark and Maldonado sp. n. are described from Venezuela. Nymphal descriptions based on reared specimens are given for A. segnini, A. muesca Stark, A. paleta Stark, two unassociated females, and an additional species being described by colleagues.

Drumming Signals of Japanese Calineuria Species (Plecoptera: Perlidae)

The drumming signals of two Japanese stonefly species are here described for the first time. Both species belong to the same genus Calineuria but the signals differ clearly as to the method used in the production of the first part of the signal, as to the tapping frequency and the duration of the whole signal.

Nonparametric evaluation of environmental parameters determining the occurrence of stonefly larvae (Plecoptera) in streams

This study explored the relationship between the occurrence of stonefly species, stream type and basic environmental conditions. Only 13 taxa, out of 115 species occurring in catchments investigated in the Czech Republic (Soldan, Zahradkova, Helessic, Dusek and Landa, 1998), were selected for this study. The environmental parameters chosen were those that characterized the hydraulic and physical environments of almost all the streams: slope, current velocity, discharge regime, bottom roughness, current type (Reynolds number and Froude number). Organic water pollution, characterized as BOD5 and saprobity, was intentionally not embodied in the evaluation, because the chosen sampling sites were in streams which proved to have minimal or almost no organic pollution. The relationships between the occurrence of stoneflies and the stream types (as set out by Illies and Botosaneanu, 1963) were evaluated on the basis of chi-square tests. For two species (Nemurella pictetii - crenal and Perla burmeisteriana - epipotamal) there was strong evidence of affinity to the stream type. The following parameters were shown to have a statistically significant influence on stonefly communities: slope, substrate roughness, current velocity and current type (Reynolds number and Froude number). For the most abundant individual species, Perla burmeisteriana, Isoperla grammatica, Leuctra albida, Leuctra nigra and Isoperla sudetica the influence of the investigated factors on occurrence and species abundance was assessed.

Structure of the ovaries in larvae and mature females of euholognathan stoneflies (Plecoptera)

AbstractThe morphology of ovaries, oviducts and egg capsules in four species of euholognathan stoneflies was investigated. The characteristic features found were as follows: (i) numerous, long ovarioles, that open individually to the extensively folded, lateral oviducts; (ii) a thin, morphologically undifferentiated chorion; (iii) a thick gelatinous layer (extrachorion) which acts as an adhesive layer fixing the eggs to the substrate. Additionally, in the larval ovariole of Leuctra sp. the terminal filament anlage and clusters of germ cells have been found. These observations are in agreement with the classification of stonefly ovaries as primary (true) panoistic.

Patterns of genetic differentiation and gene flow in Central Italian populations of Dinocras cephalotes (Curtis, 1827) (Insecta, Plecoptera)

Dispersal is a crucial phenomenon which has a strong influence on the ecology and evolution of species, determining the extent of gene flow among conspecific populations. In this paper, we present data on the degree of genetic structuring in 11 populations of the stonefly Dinocras cephalotes, focusing our attention on three Central Italian rivers: Aniene, Nera and Velino. We studied the genetic variation at 28 enzymatic loci by means of starch gel electrophoresis: 19 loci were polymorphic in one population at least. The degree of genetic structuring and levels of gene flow were estimated by F-statistics using WEIR & COCKERHAM'S estimators. Relatively high levels of genetic differentiation were revealed, considerably higher than those obtained in other studies of stonefly species. Neighbour-joining analysis provided a geographic scheme of relationships of the study populations, grouping them according to the river of origin. This analysis was supported by bootstrap values. We were not able to detect an unequivocal relationship between gene flow and geographic distances between sites within each river; this led us to hypothesise that equilibrium has not been reached between genetic drift and gene flow.

Stoneflies (Plecoptera) in some volcanic mountain ranges of the West Carpathians (Slovakia) and the impact of human activities

44 stonefly species were recorded in the Pol'ana mountains (Central Slovakia). A typical representative of the west-east fauna, Rhabdiopteryx navicula, was found. The Hučava stream basin represents the southern border of the montane and submontane distribution of stonefly species, which are bound to the river basins in high and central mountain regions of the West Carpathians. Six characteristic associations of stoneflies were recorded. Shredders predominated in the upper, and scrapers and collectors in the lower section of the Hučava stream. Detritivores were more abundant in the gravel-to-sandy mesohabitat, whereas predators and scrapers prevailed in rocky mesohabitat. Total annual production was low — 340.4 g · m −2 (dry weight), though being three-times higher in the rocky mesohabitat than in the gravel-to-sandy mesohabitat. The annual P/B ratio of stoneflies reached 3.3. Clear-cutting and operation of small hydropower stations were found to have a significant impact on the taxocoenoses of stoneflies.

Male calling, mating and oviposition in Isoperla curtata (Plecoptera: Perlodidae)

The reproductive biology (drumming call, mating behaviour, fecundity and egg structure) of Isoperla curtata, an endemic species from the Southern Iberian Peninsula, is described. The male's mating call has a diphasic pattern, with a mean of 17.3 beats per call (range = 8-27; SD = 4.7) and a duration of 792.9 ms per call (range = 228-1312; SD = 307.9). This call differs from that of other species of Isoperla in having two distinct phases with different millisecond intervals, and is species-specific. Mating lasts between 131 and 3864 seconds (mean = 2180.9 s and SD = 1027.8). Since males and females mate more than once (mean number of matings per female was 1.85 and per male 2.25), the species is polyandric and polygynic. The position adopted by the male during mating is different from that described for other stonefly species. Other mating behaviours are interpreted as displacement manoeuvers, tactile stimulation and possibly sexual selection by cryptic female choice. There was a statistically significant correlation between size and the number of matings in females (r = 0.849; p = 0.016), but not in males. Each female laid between one to four egg masses composed of an average of 88.7 eggs. Maximum fecundity was 319 eggs. The mean egg volume was 80.5 × 105 µm3 which is very similar to that of other Isoperla species. An outstanding morphological characteristic of the egg is the lobed outline of the chorion cells.

Imaginal Feeding of Twelve Nemouroidean Stonefly Species (<I>Insecta,</I> <I>Plecoptera</I>)

We studied the gut contents of adults of 12 stonefly species of the superfamily Nemouroidea, belonging to 3 different families: Nemouridae (4 species), Capniidae (2 species), and Leuctridae (6 species) from the Sierra Nevada Mountains in Spain (southern Iberian Peninsula). For each species, we describe the male and female diet. After determining and quantifying the different components, we deduced that feeding is important among adults in this superfamily, and that the diet is varied, with cyanolichens and cyanophyceae being prominent, and hyphae and spores of Ascomycetes sometimes eaten, whereas pollen is amply consumed by some spring or spring-summer species.

Contrasting diel activity and feeding patterns of four species of carnivorous stoneflies

Summary1. The hypothesis under test was that larvae of Dinocras cephalotes (Curtis), Perla bipunctata Pictet, Isoperla grammatica (Poda), and Perlodes microcephalus (Pictet) differed markedly in their diel activity and feeding patterns. Mature larvae collected about 1 month prior to adult emergence were used either for gut analyses or for observations of their activity and feeding patterns in three stream tanks with natural substrata and glass bottoms, so that activity could be observed above and below the substratum. A dull red light was used for observations in the dark. Food (larvae of Ephemeroptera, Simuliidae, and Chironomidae) was provided in excess.2. Larvae for gut analyses were taken 1 h before dusk or dawn (n = 30 larvae per species for each day or night sample). The only species with food in the gut for the day samples was P. microcephalus. All species fed at night, the mean number of prey per larva being very similar for D. cephalotes, P. bipunctata, and I. grammatica but significantly higher for P. microcephalus. Most prey were insect larvae, especially Simuliidae and Chironomidae.3. Diel activity patterns of single larvae differed interspecifically but not intraspecifically. Larvae of D. cephalotes and P. bipunctata were rarely active during the day; their activity increased at dusk and decreased at dawn, and was highest during the night; their success at prey capture was highest at dusk and dawn, with an ambush rather than a search strategy. Isoperla grammatica was rarely active during the day, most active at dusk and dawn when prey capture was highest, using a search strategy, and less active for the rest of the night. Perlodes microcephalus was active during the day, but only below the substratum, and very active from dusk to dawn with a high prey‐capture success, using a search strategy. These experiments provided support for the hypothesis under test. The discussion concludes that the results could also help to explain known differences in growth rate and the length of the life‐cycle in these four species.

A New Species of the Genus Skwala Ricker from Central Japan (Nagano Pref.) (Plecoptera: Perlodidae)

Skwala natorii, a new species of stonefly, is described from both sexes and nymphs collected in Central Japan (Nagano Pref.). Eggs of the species are shown on SEM photomicrographs.

New North American Records of Aquatic Insects as Paratenic Hosts of Pheromermis (Nematoda: Mermithidae)

Several species of aquatic insects in Trout Park Nature Preserve (Elgin, IL) were observed to have small, black spots (<0.1 mm diameter) visible within their bodies. Microscopic examination revealed these spots to be coiled juveniles of a mermithid (Nematoda: Mermithidae). Based on host habitat (seepage areas and rivulets), host species (aquatic insects), and size (mean diameter of coiled juveniles=79 μm), it is likely that these mermithids were in the genus Pheromermis. Since adult mermithids were not found, species determination was not feasible, and the possibility of a new species cannot be ruled out. Pheromermis pachysoma and Pheromermis vesparum, however, are two species known to use aquatic insects as paratenic (i.e., transport) hosts in order to reach their definitive hosts, vespid wasps. Wasp larvae are infected by consuming the flesh of adult aquatic insects that contain the coiled juveniles of these Pheromermis spp. Of the 19 macroinvertebrate species examined in this study, Pheromermis juveniles were found in 4 caddisfly species (Hesperophylax designatus, Lepidostoma liba, Glossosoma intermedium, and Diplectrona modesta) and in 2 stonefly species (Clioperla clio and Amphinemura delosa). In addition to all 6 insect species being new host records for Pheromermis infection, this also represents the first report of nematode infection in stoneflies within the Western Hemisphere and of a Pheromermis sp. in Illinois. Among trophic groups, insect detritivores have been frequently recorded infected with coiled Pheromermis juveniles because of their direct consumption of eggs, and we also observed this for detritivores in our investigation (e.g., L. liba and A. delosa). Because C. clio was intensively infected, however, our study also provided evidence that predatory insects can be paratenic hosts. Coiled juveniles were typically present in muscle and fat body and present in almost all body regions. Not every infected paratenic host had external signs of infection; thus, dissections are required for accurate determination of infection prevalence and intensity. Our findings, in conjunction with those made in previous studies, indicate that a wide variety of aquatic insects may be used as paratenic hosts by Pheromermis. Because of their small size, it is highly likely that coiled juveniles are either overlooked or mistaken for melanized integumental wounds during field studies of aquatic insects. A more careful inspection for these coiled juveniles in aquatic insects, especially detritivores and their predators in seepage areas, would probably reveal that Pheromermis is far more common than presently documented.

Imaginal Feeding of Certain Systellognathan Stonefly Species (Insecta: Plecoptera)

The digestive contents of adult males and females of 4 species of Systellognathan stoneflies were studied and analyzed: Perla marginata (Perlidae), Isoperla grammatica and I. nevada (Perlodidae ) and Chloroperla nevada (Chloroperlidae) . The study was conducted throughout the flight periods of these species in Sierra Nevada (Granada, Southern Iberian Peninsula), to determine possible variations in diet over time. The species of the families Chloroperlidae and Perlodidae fed during the adult stage, and the proportion of the different dietary components changed over the flight period in relation to the availability of such components. The data obtained for P. marginata, based on few specimens, indicated that feeding had little importance during the imaginal life.

Distribution Patterns, Species Assemblages and Habitat Selection of the Stoneflies (Plecoptera) from Two Mediterranean River Basins in Southern Spain

AbstractThe stonefly distribution and its relationship with habitat changes, based on stream physico chemical features, were investigated in two Mediterranean river basins (Guadaira and Guadalete, S Spain). Plecopteran nymph distribution varied along an elevation gradient. Both stonefly species richness and species diversity increased with altitude. Stoneflies were able to tolerate a wide range of environmental conditions but were absent from low altitude sites, temporary streams with high salinity values and high water temperature. A total of 13 stonefly species were found in the study area, from which Tyrrhenoleuctra minuta (Klapálek) and Protonemura sp. were dominant. The most widespread species were Nemoura lacustris and Capnioneura mitis. Three distinct species assemblages were observed according to their distribution patterns, but with similar environmental preferences. Capnioneura petitpierreae and T. minuta showed preferences to low altitude sites, whereas C. mitis and N. lacustris were found throughout all sites. T. minuta and N. lacustris inhabited permanent and temporary sites, while the same species and C. mitis also were found in semipermanent streams. Temporally, most stoneflies were caught during winter (85.9%), especially at the low altitude sites.

Effects of size at metamorphosis on stonefly fecundity, longevity, and reproductive success.

Many organisms with complex life cycles show considerable variation in size and timing at metamorphosis. Adult males of Megarcyssignata (Plecoptera: Perlodidae) are significantly smaller than females and emerge before females (protandry) from two western Colorado streams. During summer 1992 stoneflies from a trout stream emerged earlier in the season and at larger sizes than those from a colder fishless stream, and size at metamorphosis did not change over the emergence period in either stream. We performed two experiments to determine whether variation in size at metamorphosis affected the fecundity, reproductive success and longevity of individuals of this stonefly species and if total lifetime fecundity was affected by the number of matings. In the first experiment, total lifetime fecundity (eggs oviposited) was determined for adult females held in small plastic cages in the field. Males were removed after one copulation, or pairs were left together for life and allowed to multiply mate. Most copulations occurred in the first few days of the experiment. Females in treatments allowing multiple matings had significantly lower total lifetime fecundity and shorter adult longevity than females that only mated once. Multiple matings also reduced longevity of males. Fecundity increased significantly with female body mass at emergence, but only for females that mated once. While multiple matings eliminated the fecundity advantage of large female body size, number of matings did not affect the significant positive relationship between body mass at metamorphosis and longevity of males or females. In a second experiment designed to determine if body mass at emergence affected male mating success, we placed one large and one small male Megarcys in an observation arena containing one female and recorded which male obtained the first mating. The large and the small male had equal probabilities of copulating with the female. Copulations usually lasted all night, and the unmated male made frequent, but unsuccessful attempts to take over the copulating female. Our data suggest that selection pressures determining body size at metamorphosis may operate independently on males and females, resulting in evolution of sexual size dimorphism, protandry, and mating early in the adult stage. We emphasize the importance of interpreting the fitness consequences of larval growth and development on the timing of and size at metamorphosis in the context of the complete life cycle.

New and little known species of stoneflies (Plecoptera: Nemouridae and Perlodidae) from the Russian Far East

Nemoura ussuriensis Zhiltzova sp.n., and the previously unknown males and mature nymphs of Megarcys magnilobus Zhiltzova and Isoperla ornata Zhiltzova from the Russian Far East are described and illustrated. They are compared with other congeneric species.

Winter Stoneflies (Plecoptera) in Seasonal Habitats in New Mexico, USA

Seasonal stream habitats in New Mexico supported 10 species of winter-emerging stoneflies. Winter precipitation in combination with low winter temperatures created a seasonal moisture surplus and seasonal streamflow in this semi-arid region. Study area streams were dry for long periods in spring and autumn. Two different types of seasonal (ahyporheic) habitats were identified. Small high mountain streams fed by seasonal snowmelt runoff (type M) were inhabited by Capnia decepta, Eucapnopsis brevicauda, Isocapnia vedderensis, Capnia californica, Capnura wanica, Mesocapnia werneri, Taenionema jacobii, and Capnura fibula. Mesocapnia arizonensis and M. frisoni seemed to specialize in low-elevation watercourses fed by winter rains and rising water tables (type L). Adaptations for survival during spring and autumn periods of no streamflow, desiccation, or flash flooding include small size, rapid development, and diapause during egg or larval stages.

Species composition, distribution, and summer emergence phenology of stoneflies (Insecta: Plecoptera) from Catamaran Brook, New Brunswick

Stonefly (Plecoptera) emergence was investigated between May and September of 1993 and 1994 in Catamaran Brook, New Brunswick, as part of a base-line study to evaluate the effects of timber harvest on Atlantic salmon habitat in Atlantic Canada. Thirty-one stonefly species representing seven families were identified from Catamaran Brook, of which 8 were new provincial records. Eight species, all in the families Chloroperlidae and Leuctridae, were common in both years. The cone-type emergence traps used in this study appeared to adequately sample most stonefly species except the Perlidae. There was a pronounced seasonal progression of species emerging from the brook that was generally constant for both years. However, the abundance and timing of stonefly emergence were related to both temperature and discharge patterns. Generally earlier emergence in 1994 than 1993 was probably related to warmer water in 1994 than 1993, and lower abundance in 1994 was probably related to a reduction in habitat due to unusually low water in that year.

Post‐emergence migration of stoneflies (Plecoptera) into the nearby forest

Abstract. 1. The post‐emergence lateral migration of both sexes of eight stonefly species was examined in a dystrophic, fourth‐order forest river in eastern Finland.2. For this purpose, 7351 stonefly adults were collected with eighteen trunk funnels positioned in rows of six at distances of approximately 1, 15 and 60 m from the river. A further 1880 adults were also caught from the vegetation of the bank zone by sweep netting and with slit traps.3. The species could be grouped into two types with respect to migration distance: Isoperla difformis, I.grammatica and Leuctra fusca tended to stay in the bank area, whereas Nemoura flexuosa, N.avicularis, Amphinemura borealis, L.hippopus and N.cinerea tended to disperse into the forest, so that the majority were found some distance away from the shore.4. The males of the leuctrids, N.flexuosa and N.cinerea migrated farther than the females.5. The sex ratio was significantly biased in all species except N.flexuosa. The isoperlids, leuctrids and A.borealis showed a significant predominance of females in the trunk funnel catches, but males were significantly dominant in N.avicularis and N.cinerea. The material caught by other methods reversed the ratio for I.difformis and N.avicularis. Comparison of the sex ratios of the species with other reports revealed marked variation and deviation from unity, much of which could be attributed to bias introduced by the sampling methods.6. Lateral migration seems to be the first phase in the colonization cycle, although the latter as such was not studied here. Adults of Euholognatha species migrate farther than those of Systellognatha, a difference of which may be due to their ability to feed as adults.