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Snow is the most reflective natural surface on Earth. Since fresh snow on bare sea ice increases the surface albedo, the impact of summer snow accumulation can have a negative radiative forcing effect, which would inhibit sea ice surface melt and potentially slow sea‐ice loss. However, it is not well known how often, where, and when summer snowfall events occur on Arctic sea ice. In this study, we used in situ and model snow depth data paired with surface albedo and atmospheric conditions from satellite retrievals to characterize summer snow accumulation on Arctic sea ice from 2003 to 2017. We found that, across the Arctic, ∼2 snow accumulation events occurred on initially snow‐free conditions each year. The average snow depth and albedo increases were ∼2 cm and 0.08, respectively. 16.5% of the snow accumulation events were optically thick (>3 cm deep) and lasted 2.9 days longer than the average snow accumulation event (3.4 days). Based on a simple, multiple scattering radiative transfer model, we estimated a −0.086 ± 0.020 W m−2 change in the annual average top‐of‐the‐atmosphere radiative forcing for summer snowfall events in 2003–2017. The following work provides new information on the frequency, distribution, and duration of observed snow accumulation events over Arctic sea ice in summer. Such results may be particularly useful in understanding the impacts of ephemeral summer weather on surface albedo and their propagating effects on the radiative forcing over Arctic sea ice, as well as assessing climate model simulations of summer atmosphere‐ice processes. Plain Language Summary: As sea ice declines in the Arctic, it is necessary to understand the role that sea ice plays in the Arctic climate. During summer, ice is particularly important because it acts as a barrier between the atmosphere and ocean, and shields the ocean from sunlight. Sea ice is a surface on which snowfall can accumulate. Since snow is the most reflective natural surface on earth, its presence during the sunny season can reflect significant amounts of sunlight away from the earth's surface and reduce warming. In this work, we studied the impact of summer snowfall on sea ice by combining data from buoys, satellites, and models to determine how much sunlight is reflected by short‐lived summer snow accumulation on Arctic sea ice. We learned that the average snow event raises the reflectivity of the surface by 0.08 with ∼2 cm of snow depth change. Events with more than 3 cm of accumulation lasted ∼3 days longer than average (∼3 days). Overall, summer snow accumulation reduces the amount of energy absorbed by the Arctic region by 0.086 W m−2 each year. These results help to improve our understanding of the Arctic climate and may also be useful for evaluating climate models. Key Points: Ephemeral summer snowfall increased albedo by 0.08 and decreased TOA radiative forcing by 0.086 ± 0.020 W m−2 across the Arctic Ocean in 2003–2017The average snow accumulation event led to a ∼2 cm increase in snow depth and lasted 3.4 daysOptically thick (>3 cm) snow accumulation events occurred in 16.5% of all events and lasted 6.3 days [ABSTRACT FROM AUTHOR]

We propose and describe Alobophora sandrae Cajiao-Mora & Bullard n. gen., n. sp. (Digenea: Caballerotrematidae) for specimens we collected from arapaima, Arapaima gigas sensu lato (Osteoglossiformes: Arapaimidae) in the Amazon River near Leticia, Colombia. Alobophora differs from Caballerotrema Prudhoe, 1960 by lacking head collar projections and by having clustered corner spines and a narrow head collar (4–5× wider than pharynx), whereas Caballerotrema has head collar projections, lacks clustered corner spines, and has a broad head collar (7–8× wider than pharynx). We reassign Caballerotrema annulatum (Diesing, 1850) Ostrowski de Núñez & Sattmann, 2002 to the new genus, as Alobophora annulata (Diesing, 1850) Cajiao-Mora and Bullard n. comb., and provide a supplemental description of Caballerotrema brasiliense Prudhoe, 1960 based on specimens we collected from arapaima. We also examined the holotype and a paratype of Caballerotrema piscicola (Stunkard, 1960) Kostadinova & Gibson, 2001 and concluded that C. piscicola is a junior subjective synonym of C. brasiliense. Our 28S phylogeny recovered A. sandrae sister to A. annulata, with that clade sister to a clade comprising C. brasiliense and an innominate species of Caballerotrema. Caballerotrematidae was recovered sister to Echinostomatidae. We also provide a dichotomous key to caballerotrematids based on head collar projections, corner spine arrangement, proportional pharynx and head collar breadth, testes shape and arrangement, body surface spine shape and distribution, vitellarium distribution, and abundance of prostatic cells.