Sexual dimorphism in malpighian tubules of Pteronarcys californica Newport (Plecoptera)

The Malpighian tubules in female nymphs and adults of Pteronarcys californica Newport are larger and whiter than in males. This difference is detectable in nymphs as small as 300 mg in live weight (final instar nymphs weigh 800 to 1600 mg depending on sex), and is most pronounced in late nymphs and adults. These differences are thought to be related to the increased excretory load imposed by the synthesis of ooplasm in the late female nymph and adult.         

Emergence patterns of large stoneflies (Plecoptera: Pteronarcys, Calineuria, Hesperoperla ) in a Montana river

Emergents of Pteronarcys californica, Calineuria californica , and Hesperoperla pacifica were captured with replicated emergence traps at 3 sites along the banks of Rock Creek, Montana. Pteronarcys emergence in early June was short (88% of individuals in 6 d) and attained rates of 5 m -1 d -1 (shoreline distance) and cumulative densities up to 19 m -1 yr -1 . Calineuria emerged synchronously (89% in 9 d) 2 wk later at densities up to 7 m -1 d -1 and 40 m -1 yr -1 . The less numerous Hesperoperla (5 individual m -1 yr -1 ) had a longer emergence period partially coinciding with Calineuria Median males of Pteronarcys and Calineuria emerged 2-3 d before median females; protandry was not significant Hesperoperla . Sex ratios were female-biased in Pteronarcys and Hesperoperla but male-biased in Calineuria . Size trends through emergence were very weak although females showed a greater tendency towered larger size early in emergence.     

Vegetational and geomorphic change on snow avalanche paths, Glacier National Park, Montana, USA

Six subalpine snow avalanche paths studied in 1975 were revisited in the summer of 1983, with the purpose of examining geomorphic and vegetational change that may have occurred during this eight - year period. Repeat photography and field reconnaissance were used to assess vegetational and geomorphic change. Vegetational responses to avalanches were apparent on several of the avalanche paths, generally by an increase in brush cover. Geomorphic changes were not apparent, suggesting that avalanches need not be geomorphically effective to initiate substantial vegetative disruption.      

Effects of suspended sediment on leaf processing by Hesperophylax occidentalis (Trichoptera: Limnephilidae) and Pteronarcys californica (Plecoptera: Pteronarcidae)

The effects of suspended sediments on stream invertebrate detrital processing were investigated under replicated conditions in light and temperature-controlled chambers in the laboratory. The leaf-shredding insects Pteronarcys californica and Hesperophylax occidentalis were studied. Mean daily ingestion rates were lower among insects subjected to suspended sediments (1.5 and 3.0 g/l) than insects held in suspended sediment-free environments for seven of the eight trials. In five of the eight trials, mean ingestion rates were suppressed by ≥41% when compared to insects held in suspended sediment-free environments. Feeding inhibition was typically greater at the end of the feeding trials (14 days) than at the beginning (0–4 days). The effects of suspended sediments on ingestion were apparently related to the feeding status of the insects at the time of a trial. Insects in an active feeding mode were less influenced by suspended sediment than those in an inactive feeding mode. We conclude that, depending on the season and the duration of impact, suspended sediment can suppress processing of coarse particulate organic matter and thus adversely influence important nutrient and energy pathways in low-order streams.     

Some parasites of paddlefish ( Polyodon spathula ) from the Yellowstone River, Montana

One species of copepod ( Ergasilus elongatus ), one trematode ( Diclybothrium hamulatum ), two nematodes ( Camallanus oxycephalus and Contracaecum sp.), and two cestodes ( Marsipometra hastata and M. parva ) were recovered from 17 paddlefish ( Polyodon spathula ) collected from the Yellowstone River, Montana, on 11 and 18 May 1973. The male paddlefish averaged 69.4 nematodes and 157.6 cestodes per infected fish while the females averaged 12.0 nematodes and 415.7 cestodes. The higher intensity of cestode infection in female paddlefish was attributed to their larger size and consequent greater intake of food resulting in more exposure to the cestode intermediate hosts ( Cyclops bicuspidatus ).     

Note on the occurrence of Siphlonurus autumnalis (Ephemeroptera: Siphlonuridae) in a Montana spring brook

The little-known mayfly Siphlonurus autumnalis McDunnough (Ephemeroptera: Siphlonuridae) was collected from several locations in its floodplain habitats along the Middle Fork of the Flathead River in western Montana. To confirm identification, nymphs were reared along with an associated species, S. occidentalis Eaton (Ephemeroptera: Siphlonuridae). Adults emerged from 6 September until 16 October. Habitats are described and the first photos of the 2 sexes are provided.     

Discovery of a large population of the rare winter stonefly Isocapnia mogila Ricker in the Mad River, California (Plecoptera, Capniidae)

Isocapnia mogila , a rare winter stonefly, is found in good numbers in Humboldt County, California. In the 50 years since this species was described, very few specimens were recorded from only 4 sites in California and Oregon. Emergence seems to be higher in the fall and early winter than in the late winter and spring.     

Diatom species composition and ecology of the Animas River Watershed, Colorado, USA

The diatom flora of selected sites in the Animas River Watershed, San Juan County, Colorado, was studied. Eighty diatom taxa were identified from 10 sites: 8 sites on the Animas River and 1 site each on the Cement and Cascade tributaries. The sample diatom abundance was dominated by Achnanthidium minutissimum , Encyonema silesiacum , Aulacoseira distans , Hannaea arcus , and Diatoma mesodon . The presence of teratologic specimens of Fragilaria and Achnanthidium in the samples indicated the possibility of metals contamination. Diatom diversity was low and Lange-Bertalot pollution index scores indicated little organic pollution evidenced from diatom composition. There was evidence that diatom composition at the sites was differentially affected by pH and possibly by the concentrations of Zn alone or in combination with Cd, Cu, and Fe.     

New records of Bathynellacea (Syncarida,Bathynellidae) in North America: three new species of the genus Pacificabathynella from Montana,USA

Three new species of the genus Pacificabathynella Schminke and Noodt, 1988 Schminke, H K and Noodt, W. 1988. Groundwater Crustacea of the order Bathynellacea (Malacostraca) from North America. J Crustacean Biol., 8(2): 290–299.  [Google Scholar] are described from groundwater aquifers in glaciated North America (Montana, USA). This is the first time that this genus, known previously only from the state of California, has been documented in Montana. Pacificabathynella and Paradoxibathynella Serban, 2000 Serban, E. 2000. Uenobathynella n.g., Parauenobathynella n.g., Morimotobathynella n.g., Nihobathynella n.g. et Paradoxibathynella n.g., Bathynellinae du Japón (Bathynellidae, Bathynellacea, Podophallocarida). Travaux Inst Spéol “Émile Racovitza”, 36: 3–61.  [Google Scholar] are the only genera that show sexual dimorphism in thoracopod VI. Pacificabathynella kalispellensis sp. nov. has several unique features: the setal formula of the antenna (0/2+exop/3/12/6/8/5); the setal formula of the maxilla (7/4/7/6); the presence of an epipod on thoracopod II; tufts of setulae and abundant setae on the basipod and endopod of thoracopods I to V; the epipod of thoracopod VIII female three times longer than the basipod; three smooth setae on the exopod of the female thoracopod VIII; eight spines on the endopod of the uropod and the endopod longer than the sympod, whereas the opposite is typical. Pacificabathynella stanfordi sp. nov. has several unique features: only five setae on the exopod of thoracopods II to VII, while six setae are common in the genus; only six setae on the second segment of the first pleopod; five spines on the endopod and seven setae on the exopod of the uropod. Pacificabathynella ruthae sp. nov. is the largest species and has several unique features: antennule equal in size to the antenna, whereas in the rest of the species of the genus the antenna is larger; the projection of the inner lobe of the male thoracopod VIII is bidentate and there are six spines on the endopod and nine setae on the exopod of the uropod. The three new species have slight differences in the pars molaris of the mandible and in thoracopod VIII of males, and there are other minor differences between the females and the species Pacificabathynella sequoiae. The new taxa, together with the new genus Montanabathynella described separately, represent a 30% increase in North American taxa. Considering the glaciated landscape and the fragmented nature of alluvial aquifer habitat, we believe that there is a profound lack of critical knowledge of the biogeography and biodiversity of syncarids in North America.     

Effects of wildfire and postfire floods on stonefly detritivores of the Pajarito Plateau, New Mexico

Wildfires alter the quantity and quality of allochthonous detritus in streams by burning riparian vegetation and through flushing during postfire floods. As such, fire disturbance may negatively affect detritivorous insects that consume coarse organic matter. We assessed how 2 crown fires impacted stonefly detritivores in streams of the Pajarito Plateau, New Mexico. We documented stonefly populations before and after the fires and postfire floods, and compared recovery trajectories among unburned, lightly burned, and severely burned reaches. We also conducted experiments to assess burned detritus as a food resource for Pteronarcella badia Hagen. Specifically, we characterized microbial conditioning, nutrient content, and breakdown rates of burned and unburned deciduous leaves and pine needles. We compared colonization of P. badia in field-placed leaf packs and growth of P. badia in a microcosm experiment on burned and unburned treatments. Detritivorous stoneflies in Plateau streams survived wildfire, but were extirpated from burned reaches after severe postfire floods in both Capulin and Guaje canyon. In Guaje Canyon, Amphinemura banksi Baumann and Gaufin was more resilient to flood disturbance than P. badia and recolonized soon after floods abated, whereas recolonization of A. banksi was delayed in Capulin Canyon. Experiments revealed that detritus quality did not explain slow recovery; despite reduced microbial conditioning and decomposition rates, P. badia colonized and grew well on burned detritus. Instead, postfire floods removed shredder stoneflies and their detrital resources; and traits such as body size, voltinism, and dispersal likely interacted with the postfire landscape to shape recovery trajectories in burned streams. Los incendios cambian la cantidad y calidad de la materia orgánica alóctona en los ríos mediante la quema de la vegetación ribereña; además, las inundaciones después de los incendios se llevan materia orgánica río abajo. Como tal, la perturbación por incendio puede afectar negativamente a los insectos detritívoros que consumen la materia orgánica gruesa. Evaluamos cómo 2 fuegos de copas afectaron a los plecópteros detritívoros en arroyos del Altiplano Pajarito, NM. Documentamos las poblaciones de plecópteros antes y después de los incendios e inundaciones y comparamos las trayectorias de recuperación entre áreas no quemadas, levemente quemadas y gravemente quemadas. También llevamos a cabo experimentos para evaluar los detritos quemado como fuente alimenticia para Pteronarcella badia Hagen. Específicamente, caracterizamos el acondicionamiento microbiano, el contenido de nutrientes y las tasas de descomposición de hojas caducifolias y hojas de pino quemadas y no quemadas. Comparamos la colonización de P. badia en paquetes de hojas colocadas en el campo, y su crecimiento en un experimento de microcosmos, en detrito quemado y no quemado. Los plecópteros detritívoros en los arroyos del Altiplano sobrevivieron a los incendios pero fueron extirpados de las áreas quemadas después de inundaciones severas que siguieron a incendios en los cañones Capulin y Guaje. En Guaje, Amphinemura banksi Baumann y Gaufin fue más resistente a la perturbación por inundación que P. badia y recolonizó poco después de que la inundación cedió, mientras que la recolonización de A. banksi tardó más en Capulin. Los experimentos revelaron que la calidad de los detritos no explican esta lenta recuperación; a pesar del menor acondicionamiento microbiano y las tasas de descomposición más bajas, P. badia colonizó y creció bien en detritos quemados. Es probable que las inundaciones después de los incendios se hayan llevado a los plecópteros y a los detritos que consumen, y que los rasgos tales como el tamaño del cuerpo, el voltinismo, y la dispersión hayan interactuado con el paisaje después del incendio para determinar las trayectorias de recuperación en arroyos quemados.     

Note on occurrence of Mymaromella pala Huber and Gibson (Hymenoptera: Mymarommatidae) in Montana: a new state record

The parasitic wasp Mymaromella pala Huber and Gibson (Hymenoptera: Mymarommatidae) was collected at 4 sites within a canyon reach of the Kootenai River in Lincoln County, Montana. This minute species has only recently been described, but it appears to have a large distribution throughout the United States and to be associated with upland and riparian forests. La avispa parasitaria Mymaromella pala Huber y Gibson (Hymenoptera: Mymarommatidae) se recolectó en cuatro sitios a lo largo de un cañón del Río Kootenai en Lincoln Co., MT. Hace poco que se describió esta especie diminuta, pero parece tener una distribución extensa en los EE.UU. y estar asociada con bosques altos y ribereños.     

Transverse pattern of vegetation on avalanche paths in the northern Rocky Mountains, Montana

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The pattern of vegetation on avalanche paths has usually been ascribed to the damage done by snowslides. In the northern Rocky Mountains the pattern of herbs, shrubs, and small trees appears to be more complex than could be accounted for by avalanche magnitude and frequency. The vegetation on one path in Montana illustrates that the topography of the path is a factor in the distribution of species. Three zones exist across avalanche paths: an inner zone of herbs and suffrutescent shrubs occupying a ravine, which is snow covered longer than elsewhere; flanking zones of dense shrubs and trees with flexible stems; and an outer zone of less dense shrubs that is more xeric. The pattern of vegetation seems to be due to avalanche-related stress rather than damage.        

The first record of Syncarida in Montana,USA: a new genus and species of Parabathynellidae (Crustacea,Bathynellacea) in North America

Montanabathynella salish gen. nov. sp. nov., of the family Parabathynellidae, from Montana, USA, is described. The new species displays several exclusive characters: distal endite of the maxillule with nine claws and a very large and distinctive male thoracopod 8 with four lobes in the basal penial region and a long recurved exopod without setation. It also presents a unique combination of characters: antennule seven‐segmented; antenna six‐segmented; labrum with 18 teeth; exopod of thoracopods three‐ to six‐segmented, endopod with one dorsal seta on the first and second segments and epipod only present on thoracopods 4 to 7; pleopods absent; endopod of thoracopod 8 male with two setae and exopod without setae; female thoracopod 8 having two segments, first segment with two groups of denticles and the second one with three long barbed setae; 15 spines on sympod, four spines and spinous process on endopod and 12 setae on exopod of uropod.     

Modeling aboveground biomass of Tamarix ramosissima in the Arkansas River Basin of southeastern Colorado, USA

Predictive models of aboveground biomass of nonnative Tamarix ramosissima of various sizes were developed using destructive sampling techniques on 50 individuals and four 100- m 2 plots. Each sample was measured for average height (m) of stems and canopy area (m 2 ) prior to cutting, drying, and weighing. Five competing regression models ( P T. ramosissima using average height and/or canopy area measurements and were evaluated using Akaike's Information Criterion corrected for small sample size (AIC c ). Our best model (AIC c = –148.69, ΔAIC c = 0) successfully predicted T. ramosissima aboveground biomass (R 2 = 0.97) and used average height and canopy area as predictors. Our 2nd-best model, using the same predictors, was also successful in predicting aboveground biomass (R 2 = 0.97, AIC c = –131.71, ΔAIC c = 16.98). A 3rd model demonstrated high correlation between only aboveground biomass and canopy area (R 2 = 0.95), while 2 additional models found high correlations between aboveground biomass and average height measurements only (R 2 = 0.90 and 0.70, respectively). These models illustrate how simple field measurements, such as height and canopy area, can be used in allometric relationships to accurately predict aboveground biomass of T. ramosissima . Although a correction factor may be necessary for predictions at larger scales, the models presented will prove useful for many research and management initiatives.     

Chironomidae (Diptera) of the Colorado River, Grand Canyon, Arizona, USA, II: factors influencing distribution

Biogeographic, flow regulation (water clarity and temperature), and temporal influences affect the composition of the chironomid midge assemblage in the Colorado River between Glen Canyon Dam and Lake Mead. This assemblage is dominated by euryecious Nearctic and Holarctic orthocladine taxa (23 of 38 total species, total weighted relative abundance [WRA] = 0.972) and includes a minor Neotropical component. Chironomid species richness increases over distance downstream from the dam, and dominance shifts across 3 turbidity segments. Eleven species occur in the cold-stenothermic Clearwater (CW) segment between the dam and the 1st perennial tributary (the Paria River, 26 km from the dam). Chironomid diversity increases from 18 to 24 species in the variably turbid (VT) and usually turbid (UT) segments downstream, respectively. Total Cricotopus spp. WRA is negatively correlated with distance (turbidity), white total Chironominae WRA shows the opposite pattern. In contrast to chironomid diversity, species density decreases from 0.42 species/km in the CW segment to 0.19 and 0.08 species/km in the VT and UT segments, respectively. Seasonal dominance shifts slightly from orthocladine Eukiefferiella spp. in winter (WRA = 0.101) to Cricotopus spp. (WRA = 0.165) in summer. Total WRA is lowest in spring (0.191). The assemblage is depauperate compared with other western rivers and has changed over post-dam time.     

Chironomidae (Diptera) of the Colorado River, Grand Canyon, Arizona, USA, I: systematics and ecology

We describe the chironomid midge fauna of the Colorado River between Glen Canyon Dam and Lake Mead, Arizona. This depauperate fauna, consisting of 38 species, is dominated by euryecious Nearctic or Holarctic orthocladine taxa. In addition, a small Neotropical faunal component is represented by Polypedilum obelos Sublette & Sasa and Rheotanytarsus hamatus Sublette & Sasa. The following new synonyms are given: Protenthes riparius Malloch 1915 with Tanypus bellus Loew 1866 [= Procladius (Psilotanypus) bellus (Loew)]; Cricotopus olivetus Boesel 1983 with Cricotopus (Circotopus) annulator (Goetghebuer) 1927; Cricotopus edurus Sublette & Sublette 1971 with Orthocladius infuscatus Malloch 1915 [= Cricotopus (Cricotopus) infuscatus (Malloch)]. The following new species are described: Cricotopus (Cricotopus) blinni Sublette, Cricotopus (Cricotopus) hermanni Sublette, Metriocnemus stevensi Sublette, and Cladotanytarsus marki Sublette. We discuss the distribution and ecology of each chironomid species in this large, regulated, aridlands river.     

Reproductive status and continuity of taxa of the Simulium arcticum complex (Diptera: Simuliidae) at the Clearwater River, Montana (2007, 2008, and 2009)

We made 27 collections over nine years at the Clearwater River and conducted preliminary cytogenetic analysis on 232 individuals of the Simulium arcticum complex there. Based on these preliminary findings, we analyzed an additional 1825 larvae from Clearwater collections in 2007, 2008, and 2009 to investigate the reproductive statuses of the two prevalent taxa of the complex there and to determine whether cytogenetic diversity and frequency of types were similar from year to year. We describe a cytotype new to science and a potentially derivative cytotype of S. arcticum sensu stricto. We also determine that these two taxa are present in similar frequencies from year to year and are in genetic equilibrium, suggesting that they are not reproductively isolated. This study constitutes the fourth positive test of our Geographic Distribution/Taxon Age hypothesis.