The bumble bees (Hymenoptera: Apidae: Bombus) of Arkansas, fifty years later Author Tripodi, Amber D. Department of Entomology, University of Arkansas, Fayetteville, Arkansas 72701, USA (aszalan @ uark. edu). & Current address: USDA-ARS, Pollinating Insects Research Unit, Logan, Utah 84322, USA (amber. tripodi @ ars. usda. gov). Author Szalanski, Allen L. Department of Entomology, University of Arkansas, Fayetteville, Arkansas 72701, USA (aszalan @ uark. edu). text Journal of Melittology 2015 2015-06-01 2015 50 1 17 http://dx.doi.org/10.17161/jom.v0i50.4834 journal article 10.17161/jom.v0i50.4834 2325-4467 Bombus ( Thoracobombus ) fervidus (Fabricius) ‘Yellow Bumble Bee’ Franklin (1912) reported B . fervidus as absent throughout “the greater part of Arkansas ”, but, lacking deposited specimens, its presence could not be confirmed by Chandler & McCoy (1965) . Although B . fervidus has intermittently been reported in the state ( Franklin, 1912 ; Warriner, 2011 ), and niche modeling suggests that the northwestern portion of the state could be marginally suitable for the species ( Williams et al ., 2014 ), its presence here is dubious. A recent survey of Bombus in remnant grasslands throughout the state reported B . fervidus in Boone and Franklin Counties in 2003 ( Warriner, 2011 ), the first such sightings since it was reported 90 years prior ( Franklin, 1912 ). The Boone County specimen was the only state record of this species with a deposited voucher specimen. Another historical specimen identified as B . fervidus is among the specimens in the UAAM collection: a male collected October 1, 1963 in Columbia County in the southern extreme of the state. These two specimens deposited in the UAAM collection as B . fervidus were both males, yet investigations of genitalic characters by the authors revealed that they are actually B . pensylvanicus . Males of B . fervidus superficially resemble some of the variants of male B . pensylvanicus , and the two species can be difficult to distinguish ( Mitchell, 1962 ). Although Mitchell (1962) suggests a number of external characters that can be helpful, B . pensylvanicus and B . fervidus males can only be reliably distinguished by comparing their genitalia. The most obvious difference is in the penis valves ( sensu Michener, 2007 ; Mitchell, 1962 ). The enlarged apices of the penis valves of B . pensylvanicus are long and slender, while the apices of those of B . fervidus are more truncate, with the breadth and width about equal. Additionally, the interior process of the gonostylus of B . pensylvanicus is flattened and broad, unlike that of B . fervidus . Bombus fervidus was not observed in 2011–2013 standardized surveys that we conducted throughout the northwestern portion of Arkansas , despite intensive sampling each season (number of observations = 1693). The North American distribution of B . fervidus appears to be primarily western and northeastern ( Koch et al ., 2012 ; Williams et al ., 2014 ). To date, there are no deposited specimens of B . fervidus collected in Arkansas . Although we cannot discount its occasional presence in Arkansas , it seems more likely that records of this species in Arkansas are based on misidentifications of males, rather than true occurrences. The Arkansas Natural Heritage Commission lists B . fervidus as a species of concern within the state, with a ranking of S1, an “extremely rare” species at risk of statewide extirpation, known from Boone and Franklin Counties ( ARNC, 2014 ). Investing in the conservation of species that are not true residents of an area, such as vagrants or marginal species ( i.e ., ones that occasionally occur in an area at the extreme of the species’ range margin) is an inefficient approach to conservation that squanders scarce resources ( Rodrigues & Gaston, 2002 ). Because there are no vouchered specimens of this species collected in Arkansas , we recommend that this state ranking be re-assessed. GLOSSA LENGTH: Long (6.50 ± 0.74 mm ). ADULT ACTIVE PERIOD: Not in the state. PREFERRED PLANTS: Unknown.