Using social and physical variables to assess vulnerability of northwestern Montana lakes to illegal fish introductions

The spread of non-native fish species is a common problem in lakes and streams worldwide. Species that establish viable populations in a new environment can seriously deplete populations of native species and desired sportfishes. In some instances, extirpation of a native species has occurred. In western North America, the most common avenue by which non-native species invade new waterbodies is illegal stocking by anglers, aquaculturists, and others. Thus, preventing further illegal fish introductions is of the utmost importance for native aquatic species. Using data collected by state agency personnel from 1953 to 2015, we examined multiple social and physical variables to determine the factors that best explain which lakes in northwestern Montana had past illegal fish introductions. An equation using elevation, surrounding population, and fishing pressure was found to best fit the data. This equation was then used to calculate an index of the vulnerability of lakes within the region to future illegal fish introductions. The techniques used in this study have broad applicability that can be used in many regions with illegal fish introductions, and ultimately help to alleviate the problem.

A new, transitional centrosaurine ceratopsid from the Upper Cretaceous Two Medicine Formation of Montana and the evolution of the ‘ Styracosaurus -line' dinosaurs

Ceratopsids are among the most ubiquitous dinosaur taxa from the Late Cretaceous terrestrial formations of the Western Interior of North America, comprising two subfamilies, Chasmosaurinae and Centrosaurinae. The Two Medicine Formation of northwestern Montana has produced numerous remains of centrosaurine dinosaurs, which represent three taxa previously considered valid: Rubeosaurus ovatus , Einiosaurus procurvicornis and Achelousaurus horneri . Here, we reassess the previous referral of specimens to Rubeousaurus ovatus and demonstrate that this taxon is represented solely by its holotype specimen, which was first diagnosed as Styracosaurus ovatus . One of the specimens previously referred to ‘ Rubeosaurus ’ ovatus instead represents a new eucentrosauran centrosaurine taxon diagnosed here, Stellasaurus ancellae gen. et sp. nov. Stellasaurus expresses a unique combination of eucentrosauran centrosaurine characters, including an elongate nasal horncore, diminutive supraorbital horncores, and a parietal bearing straight, elongate P3 processes, semi-elongate P4 processes and non-elongate P5, P6 and P7 processes. Within the stratigraphic succession of Eucentrosaura, Stellasaurus occurs intermediate to Styracosaurus albertensis and Einiosaurus , and likewise reflects intermediate morphology. Assessed within the stratigraphic, geographical, taphonomic, ontogenetic and phylogenetic framework of Unified Frames of Reference, we fail to reject the hypothesis that Stellasaurus ancellae represents a transitional taxon within an anagenetic lineage of eucentrosauran centrosaurines.

Surveys for terrestrial gastropods in the Kootenay region of British Columbia, with new records and range extensions

The northern Columbia River basin, extending from the Kootenay region in British Columbia southward to the Idaho panhandle and northwestern Montana, contains a unique terrestrial gastropod fauna, but in Canada few surveys have specifically targetted this group. Here we report on terrestrial gastropods detected during surveys of 314 sites distributed in five biogeoclimatic zones across the Kootenay region. The surveys occurred on 65 days over seven years from 2007 to 2015, usually in September–October. We detected 45 taxa identified to species, belonging to 33 genera; micro-snails of the genus Vertigo (apart from Vertigo ovata) were combined into a single category, and snails belonging to Succineidae were not identified further. Regionally endemic species previously reported from the region included Western Banded Tigersnail (Anguispira kochi occidentalis), Coeur d’Alene Oregonian (Cryptomastix mullani), Rocky Mountainsnail (Oreohelix strigosa), Subalpine Mountainsnail (Oreohelix subrudis), and Pale Jumping-slug (Hemphillia camelus), which was widespread across the region. Magnum Mantleslug (Magnipelta mycophaga), the distribution of which extends beyond the Kootenay region, was detected at several widely spaced sites. Two species new to Canada were detected, Pygmy Slug (Kootenaia burkei) and Sheathed Slug (Zacoleus idahoensis), both of which were subsequently assessed to be of conservation concern both provincially and nationally. Other notable observations included the detection of Fir Pinwheel (Radiodiscus abietum), a regional endemic, which has been previously reported only once, and three species common in coastal forests but not previously reported from the region: Pacific Banana Slug (Ariolimax columbianus), Robust Lancetooth (Haplotrema vancouverense), and Northwest Hesperian (Vespericola columbianus). Further surveys, especially at higher elevations, may reveal other additional or unusual species.

The oldest Inocelliidae (Raphidioptera) from the Eocene of western North America

One new genus of Inocelliidae (Raphidioptera) with one new species and one undetermined specimen is described from the Eocene of North America: Paraksenocellia borealis new genus, new species from the early Eocene (Ypresian) Okanagan Highlands shale at Driftwood Canyon, British Columbia, Canada (a forewing), and Paraksenocellia species from the middle Eocene (Lutetian) of the Coal Creek Member of the Kishenehn Formation, northwestern Montana, United States of America (a hind wing). These are the oldest records of the family. The new genus possesses many character states that are rare in Inocelliidae, e.g., a very long pterostigma extending to ScP in both the forewings and hind wings; the forewing subcostal space has three crossveins; the forewing and hind wing AA1 are deeply forked; the crossvein between CuA and CuP is located far distad the crossvein 1r-m. Paraksenocellia is confidently a member of the Inocelliidae, as it possesses a proximal shift of the basal crossvein 1r-m (connecting R and M) in the forewing and the loss of the basal crossvein 1r-m in the hind wing, both apomorphies of the family. It shares some character states with the Mesozoic Mesoraphidiidae, which we consider to be mostly stem-group plesiomorphies.

Millennial scale climate-fire-vegetation interactions in a mid-elevation mixed coniferous forest, Mission Range, northwestern Montana, USA

Mixed coniferous forests are widespread at middle elevations in the Northern Rocky Mountains, yet relatively little is known about their long-term vegetation and fire history. Pollen and charcoal records from Twin Lakes, in the Mission Range of northwestern Montana provide information on mixed-coniferous forest development and fire activity over the last 15,000 years. These data suggest an open parkland and minimal fire activity before 13,500 cal yr BP, consistent with cold, dry conditions. Increases inPinuspollen after 13,500 cal yr BP indicate a transition to closed forests, and a slight rise in fire activity as conditions warmed and fuel biomass increased. High levels ofArtemisiapollen between 10,000 and 6000 cal yr BP suggest an open forest during the early Holocene when conditions were warmer and drier than present. Low-severity fires likely maintained open forest/shrublands but produced little charcoal during this interval. Present-day mixed-coniferous forests were established in the last 6 ka and included forest taxa characteristic of low- (Pseudotsuga-Larix/Pinus ponderosa)and high-severity fire regimes (Picea/Abies). Increased climate variability and anthropogenic burning may have helped maintain heterogeneous, mixed-coniferous forests during the last several millennia when climate conditions became cooler and wetter.