Derek A. Woller2
and Derek S. Sikes1
1University of Alaska Museum, 1962 Yukon Dr., University of Alaska Fairbanks, Fairbanks, Alaska, 99775, United States
2USDA APHIS PPQ S&T Phoenix Lab Rangeland Grasshopper and Mormon Cricket Management Team, 3645 East Wier Ave., Phoenix, Arizona, 85040, United States
* Corresponding author: firstname.lastname@example.org
Derek A. Woller2
and Derek S. Sikes1
1University of Alaska Museum, 1962 Yukon Dr., University of Alaska Fairbanks, Fairbanks, Alaska, 99775, United States
2USDA APHIS PPQ S&T Phoenix Lab Rangeland Grasshopper and Mormon Cricket Management Team, 3645 East Wier Ave., Phoenix, Arizona, 85040, United States
* Corresponding author: email@example.com
Currently, 18 species of Orthoptera are known from Alaska, representing the families Acrididae, Tetrigidae, and Rhaphidophoridae. There is considerable overlap in fauna between Alaska and the adjacent provinces of British Columbia (BC) and the Yukon Territory. Thirteen of the species known from Alaska also occur in both BC and the Yukon, two others are shared with just BC, two with just the Yukon, and one species is known only from Alaska and the Palearctic. We here present a photographic dichotomous key to adults of all 18 species, as well as updated distribution maps and a review of the available DNA barcode data. Stethophyma grossum (Linnaeus, 1758) is added as a new state and continent record based on a combination of molecular and morphological evidence. Stethophyma lineatum (Scudder, 1862) is subsequently removed from the Alaskan fauna. Melanoplus gordonae Vickery, 1969, previously believed to be an Alaskan endemic, is synonymized under Melanoplus borealis (Fieber, 1853). DNA barcoding results suggest that there may be undocumented diversity within Alaskan Pseudochorthippus curtipennis and Tetrix subulata (Linnaeus, 1758).
Arphia conspersa Scudder (photo by Brian Lotze)
Orthoptera (grasshoppers, crickets, and katydids) are among the most familiar and easily recognized insects. Orthopteran diversity is greatest in the tropics and decreases towards the poles. Alaska lies mostly above the 60th parallel where low temperatures and a short growing season act as strong filters to northward dispersal (Fielding 2004; Fielding and Defoliart, 2007; Kaufmann 2017). As such, of the 1,200 or so North American species, only 18 are known from Alaska (Table 1). The short-horned grasshoppers (Acrididae), dwarf grasshoppers (Tetrigidae), and camel crickets (Rhaphidophoridae) are represented, but the nocturnal-singing true crickets (Gryllidae) and katydids (Tettigoniidae) are conspicuously absent. Fifteen Alaskan species are shared with the 18 species that occur in the Yukon (Vickery 1997). The three not known from Alaska are Stethophyma lineatum (Scudder, 1862), Melanoplus packardii Scudder, 1878, and the Yukon-endemic Bruneria yukonensis Vickery, 1969. The last species has been collected less than 150 km from the Alaskan border, however, so Bruneria yukonensis may be present in eastern Alaska but has yet to be collected (Catling 2008). Rugged geography and limited road access have left much of the state, particularly the western half, under-sampled (Fig. 1).
Figure 1. Map of Orthoptera collection records in Alaska. The most thoroughly sampled localities are Palmer (1286 specimens), Denali National Park & Preserve (939), Prince of Wales Island (287), and Fairbanks (273). Numbers in colored circles correspond to specimen record counts and colors indicate orders of magnitude, with blue = 1-9, yellow 10-99, red 100-999, purple <1000.
Three species, Melanoplus sanguinipes (Fabricius, 1798), M. borealis (Fieber, 1853), and Camnula pellucida (Scudder, 1862), are significant agricultural pests (Pfadt 2002). Although normally in low abundance, they can reach outbreak levels when unusually warm summer temperatures enable rapid maturation (Washburn 1953). Alaska is warming faster than any other state, and we can expect outbreak conditions to be met more frequently as mean summer temperatures rise (Serreze et al. 2000; Walsh et al. 2008). For example, warming has already contributed to intensified outbreaks of spruce beetles (Dendroctonus rufipennis Kirby, 1837) on the Kenai Peninsula (Berg et al. 2006).
During the last glacial maximum, Interior Alaska formed part of an ice-free refugium known as Beringia. At this time, the Bering Land Bridge allowed for species exchange between ice-free Alaska and eastern Siberia, but ice sheets blocked dispersal to the rest of North America. Beringia was characterized by an open steppe grassland with no modern analogue (Young 1982). Habitat restrictions or low dispersal ability may have therefore prevented some species from spreading into deglaciated Canada at the end of the Pleistocene. This complex biogeographic history has led to intercontinental disjunctions and endemic species (e.g., Sikes et al. 2016). Catling (2008) listed three Alaskan species as having a Beringian distribution: Aeropedellus arcticus Hebard, 1935, Bohemanella frigida (Boheman, 1846), and Xanthippus brooksi Vickery, 1967.
At the start of our investigation, an additional species, M. gordonae Vickery, 1969, was recognized from Alaska. Melanoplus gordonae was known only from the type specimens collected near Fairbanks, Alaska, in 1969. Subsequent efforts to recollect it had failed, leading us to believe that it was either a rare endemic or, possibly, extinct. However, these assumptions were called into question when we examined unidentified Melanoplus specimens in the University of Alaska Museum (UAM) Insect Collection that exhibited some morphological traits characteristic of M. gordonae, but not the distinctly trilobate male subgenital plate described by Vickery (1969) as the primary distinguishing character of the species. These specimens did not key out cleanly to any known Alaskan species using existing keys for Alaska and Yukon, Canada (Vickery 1969; Vickery and Kevan 1985 (1986); Catling 2008). These findings prompted an investigation into the taxonomic status of M. gordonae, which is described herein.
Our goal was to review all available literature, specimen, and DNA barcode data to produce a complete and concise resource for identifying the known Alaskan Orthoptera. This key includes high-resolution color photographs of each species and all diagnostic characters, as well as updated species distribution maps. Synanthropic species that can only survive indoors in Alaska, such as Acheta domesticus (Linnaeus, 1758), are not included. We incorporated recent taxonomic changes as well as many new collection records.
A brief overview of Orthoptera research in Alaska
The earliest known Alaskan Orthoptera specimens were collected by Robert Kennicott, who, in 1860, descended the Yukon River as far west as Fort Yukon, Alaska (Foster 1913). He collected the state’s first records of Arphia conspersa Scudder, 1875, M. borealis, M. sanguinipes, and a new species named in his honor: M. kennicottii Scudder, 1878 (Scudder 1875, 1878, 1897). He returned to Alaska in 1865 but died unexpectedly in the spring of 1866 before he could collect more specimens (Schlachtmeyer 2010).
Collections were rare for the remainder of the 19th and early 20th centuries. In 1893, T.C. Mendenhall contributed three specimens of M. bruneri Scudder, 1897 to the U.S. National Museum while surveying the boundary between Alaska and Canada (Scudder 1897). In 1899, Trevor Kincaid, entomologist of the Harriman expedition, collected 14 individuals of M. borealis at Kukak Bay, the only Orthoptera among his 8,000 specimens (Caudell 1900). In 1912, J.M. Jessups of the Canadian Arctic Expedition collected B. frigida along the 69th parallel (Caudell 1915; Weber 1950), which was a new record for Alaska as well as the western hemisphere.
Grasshoppers have traditionally been overlooked by the general Alaskan public (perhaps due to limited abundance), so much so that they were “considered a novelty by many and in some areas of the state have been written up as a news story when noticed…” (Washburn 1965). This changed in 1951 when there was an outbreak of M. sanguinipes on agricultural lands near Butte, Alaska. Grasshopper densities reached an incredible 300 individuals per square yard (Washburn 1953). A subsequent outbreak in 1953 was only halted after a float plane sprayed crops with Aldrin, a now-banned insecticide. This was the first example of an airplane suppression program for agricultural pests in Alaska (Washburn 1965). Outbreaks of this and other species continued sporadically for several decades. In 1990, a fungal pathogen, “Entomophaga praxibuli,” was experimentally released as a biological control agent at two sites near Delta Junction, but the project was halted due to poor results and later concerns for non-target grasshopper species (Goodman 1993; Hostetter 1996-2000, Quarberg and Jahns 2002). The outbreaks ceased in 1992 when late spring and early autumn snow greatly reduced populations by interrupting lifecycles (Quarberg and Jahns 2002).
Alaska’s most prolific collector of Orthoptera was Richard Washburn. He collected over 1,200 specimens (now part of the UAM insect collection) during his 29 years at the Agricultural Experiment Station in Palmer, Alaska, from 1950-1979 (Murray 1979). Among his contributions were a detailed description of the life history of M. sanguinipes in Alaska and collection of the first state record of Tetrix subulata (Linnaeus, 1758) (Rehn 1952; Washburn 1965).
In recent decades, The University of Alaska Fairbanks and the U.S. Department of Agriculture have conducted extensive work on the physiology and ecology of sub-arctic Melanoplini (e.g., Fielding 2004; Fielding and Defoliart 2007; Zhang and Fielding 2011). The UAM has expanded its collection of Alaskan Orthoptera to over 3,000 specimens due to extensive sampling in Denali National Park & Preserve and on Prince of Wales Island (Fig. 1). The museum’s DNA barcoding efforts have also identified new state records and potential cryptic species (Sikes et al. 2017).
Table 1. Checklist of Alaskan Orthoptera with count of specimens in UAM and count of DNA barcoded UAM specimens.
|Caelifera||Number of specimens in UAM||Number of specimens with DNA barcodes|
|Aeropedellus arcticus Hebard, 1935||773||2|
|Chloealtis abdominalis (Thomas, 1873)||9||3|
|Pseudochorthippus curtipennis (Harris, 1835)||45||3|
|Bohemanella frigida (Boheman, 1846)||166||0|
|Melanoplus borealis (Fieber, 1853)||75||2|
|= Melanoplus gordonae Vickery, 1969, syn. nov.|
|Melanoplus bruneri Scudder, 1897||18||0|
|Melanoplus fasciatus (Walker, 1870)||14||2|
|Melanoplus kennicottii Scudder, 1878||0||0|
|Melanoplus sanguinipes (Fabricius, 1798)||1213||2|
|Arphia conspersa Scudder, 1875||19||2|
|Camnula pellucida (Scudder, 1862)||56||6|
|Stethophyma grossum (Linnaeus, 1758)||2||1*|
|Xanthippus brooksi Vickery, 1967||0||0|
|Tetrix brunnerii (Bolivar, 1887)||4||4|
|Tetrix ornata (Say,1824)||6||0|
|Tetrix subulata (Linnaeus, 1758)||70||12|
|Pristoceuthophilus cercalis Caudell, 1916||279||2|
|Tropidischia xanthostoma (Scudder, 1861)||1||0**|
* Attempted DNA barcoding on 2nd specimen, which failed
** DNA barcoding failed
The key presented here is for adult Orthoptera and is based largely on the works of Vickery and Kevan (1985 (1986)) and Catling (2008) who covered the Alaskan species in their keys to the Canadian fauna. Adults for all Alaskan species can be distinguished from nymphs by the presence of fully developed wings, except in the case of the two Rhaphidophoridae species whose life stages all resemble one another with the exception of relative size (adults being the largest and most robust) and presence of fully developed cerci and genitalia. Taxonomy used here follows that of the most current Orthoptera Species File (Cigliano et al. 2020). Morphological terminology is consistent with that of Catling (2008). An informational overview for each species follows the key and is organized alphabetically by genus and then specific name. A list of institutions that contributed specimens, photographs, and distribution data can be found in Table 2.
Table 2. List of institutions that provided specimens, photographs, and GBIF.org distribution data.
|ANSP||The Academy of Natural Sciences of Drexel University, Philadelphia, PA, USA||-||yes||-|
|ASUHIC||Arizona State University Hasbrouck Insect Collection, Tempe, AZ, USA||yes||yes||-|
|BYUC||Brigham Young University Monte L. Bean Life Science Museum, Provo, UT, USA||-||-||yes|
|CSUC||Colorado State University C. P. Gillette Museum of Arthropod Diversity, Fort Collins, CO, USA||-||-||yes|
|KNWR||Kenai National Wildlife Refuge, Soldotna, AK, USA||-||-||yes|
|LEMQ||McGill University Lyman Entomological Museum and Research Laboratory, Ste. Anne de Bellevue, Quebec, Canada||yes||yes||yes|
|OMNH||University of Oklahoma, Oklahoma Museum of Natural History, Norman, OK, USA||-||-||yes|
|OSUM||Ohio State University Museum of Biological Diversity, Oberlin, OH, USA||-||-||yes|
|UAM||University of Alaska Museum of the North, Fairbanks, AK, USA||yes||yes||yes|
|UBCZ||University of British Columbia Spencer Museum, Vancouver, British Columbia, Canada||-||-||yes|
|UMMZ||University of Michigan Museum of Zoology, Ann Arbor, MI, USA||-||yes||yes|
|USDA APHIS PPQ S&T||Phoenix Lab Rangeland Orthoptera Collection, Phoenix, AZ, USA||yes||yes||-|
|USNM||National Museum of Natural History, Washington, D.C., USA||-||yes||yes|
|UWBM||University of Washington Burke Museum of Natural History and Culture, Seattle, WA, USA||-||-||yes|
This key should correctly identify males and short-winged females of all species. However, difficulty may arise for some long-winged females, specifically for the species M. bruneri, M. sanguinipes, and Melanoplus fasciatus (Walker, 1870). To explain, both Vickery and Kevan (1985 (1986)), and Catling (2008) relied on a combination of ventral coloration of the hind femur and cercus shape to distinguish females of M. bruneri and M. sanguinipes. Catling (2008) describes M. bruneri as having a “hind femur entirely yellowish below; upper side of cercus straight” and M. sanquinipes as having a “hind femur with pink or reddish stripe below; upper side of cercus convex.” However, we found these characters to be variable in the Alaskan specimens we examined. For example, many specimens of M. sanguinipes in the UAM collection have straight cerci, and the undersides of their femora are yellow, red, pink, or pink-striped. Furthermore, preserved specimens are often faded or discolored, limiting the usefulness of this color-based character. Thus, our key is not designed to distinguish between females of M. bruneri and M. sanguinipe meaning some specimens will key out inconclusively. This issue will only be rectified by collecting and examining a longer series of Alaskan M. bruneri in order to develop more reliable characters. Like M. buneri, reliable identification of M. fasciatus females will only be possible with more specimens because, as of yet, insufficient numbers have been collected from Alaska. Therefore, the current best methods for identifying females of these species are either examining hind femora coloration in newly collected specimens or by association with males.
We identified UAM specimens by use of the prior mentioned keys in combination with identifications made by the following orthopterists: A. B. Gurney, P. Naskrecki, D. Nickle, and J. Rehn. Specimen data were compiled from the literature, UAM records, and by searching GBIF.org (doi.org/10.15468/dl.h86qrh) (GBIF.org 2020). UAM specimen data are publicly available via the Arctos database (arctos.database.museum/saved/Orthoptera), which serves data to GBIF.org among other data aggregators. GBIF.org records were limited to those based on preserved specimens and those with verifiable photographs. Literature records were georeferenced following the MaNIS georeferencing guidelines (Chapman and Wieczorek 2006), and distribution maps were then created in R (R Core Team 2018). DNA barcode data were archived on the Barcode of Life Database (BOLD) website (http://www.boldsystems.org) (Ratnasingham and Hebert 2007).
Body length measurements for the acridids and tetrigids were taken from Catling (2008). Specimens of the two rhaphidophorids were measured from the front of the head (excluding the antennae) to the tip of the abdomen and the mean length for each sex is reported. For Pristoceuthophilus cercalis Caudell, 1916, ten UAM specimens of each sex were measured. For Tropidischia xanthostoma (Scudder, 1861) males, only one Alaskan specimen was available, and its length is reported. Female length was based on nine specimens from California as no specimens from Alaska or Canada were available.
Except for living specimens, images for the key were taken with either a Leica Microsystems DFC425 camera attached to a Leica MZ16 microscope or a Macroscopic solutions Macropod Pro 3D imaging system attached to a Canon EOS 6D Mark II DSLR camera with a 65 mm lens. Multiple images were taken at different focal lengths and then stacked into a single composite image. Images from the Leica DFC425 were processed with Leica Application Suite V3.8, and images from the Macropod system were processed using Zerene Stacker (Build T2020-05-22-1330). Adobe Photoshop was used to add scale bars and adjust light levels. All images were taken using UAM specimens unless otherwise noted.
Figure 2. Left lateral view of a female grasshopper (Acrididae) illustrating characters used in the key.
Figure 3. Dorsal view of the male terminalia of a grasshopper (Acrididae) illustrating characters used in the key.
Melanoplus borealis (Fieber, 1853)
Melanoplus gordonae Vickery, 1969, syn. nov.
We hereby establish M. gordonae Vickery, 1969 as a junior synonym of M. borealis based on accumulated morphological evidence. Melanopus gordonae was described using only five type specimens: male holotype (Fig. 4A,B,E), female allotype (Fig. 4C,D,F), and three nymphs that were collected by a V. Gordon: "U.S.A.: Alaska, nr. Fairbanks, 2 mi. along Gilmore Trail, 13-VIII-1968" (Vickery, 1969). Despite numerous efforts by Vickery and subsequent collectors, including AH and DSS, no more specimens of this species have been found, leading to the presumption that it was a very rare endemic or, possibly, extinct. However, both of these seemed unlikely since macropterous grasshopper species are seldom found to be restricted to a single small area (unlike many brachypterous and apterous species), nor do species with presumed long-range flight abilities tend to go extinct within such short time frames with the possible extraordinary exception of the Rocky Mountain locust (Melanoplus spretus (Walsh, 1866)) (Lockwood, 2004).
Regardless, these hypotheses were challenged when, during the course of this research, 18 Melanoplus spp. specimens (12 male, 6 female) found in the UAM (14 collected in the vicinity of Fairbanks, three from Palmer, and one from the Kanuti National Wildlife Refuge, Alaska) did not key out smoothly to any of the more common species found in Alaska using the three afore-mentioned taxonomic keys for Alaska and Yukon, Canada. To understand this better, it should first be mentioned that the M. gordonae holotype possesses one primary unique morphological character: the subgenital plate is distinctly trilobate at its apex (Fig. 5C). Two further characters that helped separate it from other species were the combination of wings that extended beyond the apex of the abdomen in both sexes (although this was not explicitly noted in the original description) (Fig. 4A-D) and a lack of banding on the outer face of the hind femora in males, but with some in females (Vickery 1969) (Fig. 4C). Note that the latter character was seemingly misunderstood by Catling (2008) to not be present at all. His confusion was most likely compounded by the fact that the key in Vickery and Kevan (1985 (1986)) mistakenly said that the female lacked the banding.
Close examinations of the holotype and allotype specimens from the Lyman Entomological Museum confirmed these unique characters and allowed for careful comparisons to the 18 UAM specimens, which all possess the long wings possessed by the M. gordonae type specimens, but the apices of the subgenital plates of all 12 males would be difficult to describe as distinctly "trilobate." In fact, running all 18 specimens through the three keys repeatedly identified them consistently as M. femurrubrum (De Geer, 1773), which happens to be the species that Vickery (1969) compared M. gordonae against even though it is not found in Alaska (Vickery used specimens from British Columbia, Canada). Despite this, a colleague with over 40 years of rangeland grasshopper-identifying experience also closely examined the UAM specimens, ran them through the same keys and still came to M. femurrubrum, but noted that M. borealis (Fig. 4G&H) would be a better fit in terms of overall habitus (Reuter, personal observations).
To further support this, several morphological features of the unidentified UAM specimens, including shape variation of the male subgenital plate, female subgenital plate similarities, overall cerci shape, supra-anal plate similarities, and larger body size (Figs. 4A-D, G&H; 5A-F, L), combined with their geographic location, suggested greater similarity between M. gordonae and M. borealis than M. gordonae and M. femurrubrum. However, the primary distinctions between M. gordonae and M. borealis were three-fold: 1) subgenital plate shape in males (Fig. 5C&F), 2) slight banding on outer hind femora of females (Fig. 4C) (seemingly absent in M. borealis (Fig. 69 in key)), and 3) wing length in both sexes (Fig. 4A-D, G&H). This latter character is what particularly stymied us and Reuter because, according to the three keys and other reliable sources of information (e.g., Pfadt 2002), the wings of M. borealis rarely extend beyond the apices of hind femora. These conflicts are what prompted the decision to borrow the type specimens of M. gordonae and compare the internal genitalia of the holotype to those of some of the UAM specimens and the internal genitalia of multiple male specimens of M. femurrubrum and M. borealis (all with hind wings not extending beyond the apices of hind femora). The holotype's internal genitalia (Figs. 5G-I; 6A&C) closely matched those of the UAM males, which, in turn, all closely matched those of M. borealis (Figs. 5J&K; 6B&D), both short and long-winged morphotypes. Differences in internal genitalia, particularly the shape of the valves of aedeagus, are often quite useful for delimiting Caelifera species, particularly melanoplines (Hubbell 1932), which certainly appears to be the case here.
Additional support for M. gordonae actually being M. borealis came from several other sources, the first being Gurney and Brooks (1959) who noted that M. borealis borealis (M. borealis has a complex taxonomic history and its subspecies are no longer recognized (Cigliano et al. 2020)) has variable wing length, which can be both shorter or longer than the abdomen. This species is found throughout Canada, across Alaska, and in several other northern U.S. states (Gurney and Brooks 1959; Vickery and Kevan 1985 (1986); Pfadt 2002; Catling 2008), meaning its known distribution encompasses that of M. gordonae. Several longer-winged specimens of M. borealis were confirmed by colleagues to exist in two reputable collections: the Pfadt Collection at the University of Wyoming (Wyoming specimens) and the National Museum of Natural History's melanopline collection. To further test our conspecificity hypothesis, we asked the colleague overseeing the latter collection to dissect the internal genitalia of two of these specimens from Fairbanks and Beaver, Alaska, and they were confirmed to be remarkably similar to the M. gordonae holotype.
Therefore, the preponderance of morphological evidence (similar body size, similar shape of male terminalia structures, wing length) support the synonymizing of M. gordonae with the earlier-named M. borealis. Two odd details do remain: 1) the trilobate apex of M. gordonae's subgenital plate in the holotype (Fig. 5C) and 2) the slight banding on the outer face of M. gordonae's hind femur in the allotype (Fig. 4C). But both of these can be explained as unusual population variation details, especially since the past use of the subspecies concept for M. borealis was based on high levels of population variation across regions. Some of the previously unidentified UAM male specimens do exhibit vague similarities and a range of variation (same for the previously identified M. borealis specimens examined) of the aforementioned unique male character, but none are admittedly as eye-catching as the specimen Vickery (1969) used to describe M. gordonae. Vickery (1969) simply seems to have gotten very lucky and would probably have noticed sufficient variation that might have led him to draw different conclusions if he had a larger series of specimens to examine. Finally, it should be noted that several collecting efforts made by AH and DSS in the type locality have only yielded M. borealis specimens: long-winged males and short-winged females (curiously, conversely to the M. gordonae allotype). Based on this and other Alaska-collected long-winged M. borealis specimens suggests that the region may contain relatively high numbers of this particular morphological variation, which warrants further investigation.
Identification of Orthoptera via DNA barcoding can be challenging because of incomplete lineage sorting, hybridization, numt insertions (non-functional nuclear copies of mitochondrial genes), and Wolbachia infection. All of these can commonly obscure barcode results in Orthoptera (Hawlitschek et al. 2017; Moulton et al. 2010). Nevertheless, barcoding successfully identified 76% of species in a trial of European Orthoptera (Hawlitschek et al. 2017). The BOLD database currently contains 31,473 orthopteran barcode sequences from around the world, representing 2,953 species forming 3,485 Barcode Index Numbers (BINs) (as of 16 February 2020) (Ratnasingham and Hebert 2013).
Alaska has one of the most complete non-marine arthropod DNA barcode libraries of any state or province in North America, with over 48.5% of the known nonmarine arthropod species represented by DNA barcode sequences (Sikes et al. 2017). Barcode-compliant sequences have been obtained for 12 of the 18 Alaskan orthopteran species (67% of the Orthoptera fauna), two of which are the only members of their BINs (Table 2). Of the six un-sequenced species, barcoding was attempted, but failed, for Tetrix ornata and Tropidischia xanthostoma. Bohemanella frigida and M. bruneri were not attempted because of the ambiguous results we received from prior melanoplines. No specimens of Xanthippus brooksi or M. kennicottii were available for sequencing.
Stethophyma lineatum was originally thought to be present in Alaska, based on three specimens, two collected near Fairbanks and one near Beaver on the Yukon River. However, a combination of molecular and morphological data we generated revealed that these specimens are not actually this species. One Fairbanks specimen was barcoded and the sequence clusters with the Palearctic Stethophyma grossum (Linnaeus, 1758) (BOLD:AAI0053), which has a genetic distance of 4.02% to the BIN containing S. lineatum (BOLD:AAG9096). Further investigation confirmed that all three Alaskan specimens key out to S. grossum using the key of Storozhenko and Otte (1994) because of their distinctive tibial coloration. The hind tibia of S. grossum females has a black base and black spot in the basal third. In contrast, S. lineatum females have a dark brown tibial base with or without a trace of a black spot. We therefore concluded that these specimens are S. grossum. This species is widespread throughout Europe and Siberia, but these are the first records in North America. In Europe, it is associated with wetlands and listed as Vulnerable or Near Threatened in Poland, Austria, Switzerland, Denmark, the United Kingdom, and part of the Czech Republic due to habitat loss (Hochkirk et al. 2016). More work is needed to determine the limits of its distribution in North America, its habitat preferences, and if it occurs sympatrically with S. lineatum over any of its range. A specimen of S. lineatum in the University of British Columbia Spencer Entomological Collection, collected from Halfway Lake, near Mayo, Yukon, needs verification because this locality is close to the eastern boundary of Beringia and disjunct from the majority of S. lineatum records (Catling 2008).
Two sequences, from specimens identified as Tetrix subulata and Pseudochorthippus curtipennis (Harris, 1835), are the only members of their BINs. Tetrix subulata is a widely occurring Holarctic species. The BOLD database contains 47 sequences of T. subulata, forming three monospecific BINs and one taxonomically discordant BIN (BOLD:AAG2982) that contains several Tetrix species but likely represents Tetrix brunnerii. Of the monospecific BINs, one contains all of the Palearctic sequences (BOLD:AAC3440), one contains almost all of the Nearctic sequences, including nine from Alaska (BOLD:AAY6671), and the final BIN contains a single sequence from Fairbanks, Alaska (BIN BOLD:ACJ7497). This lone sequence is not geographically isolated from the other Alaskan sequences, some of which were also collected near Fairbanks.
The P. curtipennis sequence, in BIN BOLD:ACL2935, came from one of four UAM specimens collected near Naknek, Alaska. Its nearest neighbor, at 3.88% distant, is a BIN (BOLD:AAG5331) containing sequences from four Canadian specimens identified as Pseudochorthippus montanus (Charpentier, 1825). However, P. montanus is not known from North America, so these specimens may be misidentified P. curtipennis. Unfortunately, attempts to sequence nine other Alaskan specimens failed, so we do not know if this specimen is representative of all Alaskan P. curtipennis. All other P. curtipennis sequences in the BOLD database cluster into three closely related BINs.
Sequences from the three Melanoplus species that we obtained DNA barcodes for cluster into a single taxonomically discordant BIN (BOLD:AAA4555) shared with 23 congeneric specimens. The maximum within-BIN distance is high (>2%) and exceeds the distance to its nearest neighbor. Other sequences from these species in the BOLD database cluster into several other discordant BINs. Melanoplus diversity is the result of a recent radiation during the Pleistocene (Knowles 2000; Knowles and Otte 2000), and incongruence between gene trees and species trees is well established in the genus (Carstens and Knowles 2007; Knowles 2001). Misidentification could also be a contributing factor.
These preliminary barcode results suggest that non-Melanoplini grasshoppers are suitable taxa for phylogeographic studies of Pleistocene glacial cycles. Stethophyma grossum displays a classic Beringian distribution with disjunct Palearctic and Nearctic populations, likely separated by the flooding of the Bering Land Bridge. Tetrix subulata and Pseudochorthippus curtipennis show evidence for divergent Alaskan clades, consistent with findings in other Beringian taxa (Shafer et al. 2010). However, barcoding efforts to date have focused on creating a simple species inventory, and more thorough work is needed to place Alaskan grasshoppers in the broader context of northwestern North American and to test phylogeographic hypotheses.
Table 3. Summary of BOLD records for Alaskan DNA barcoded Orthoptera as of 16 February 2020.
|Identification||Process ID||Institution||Museum ID||BIN #||Member count||Max distance w/in
|Distance to nearest neighbor (p-dist)|
We would like to thank the following contributors (organized by last name, see Table 2 for abbreviation guide) for providing specimens, specimen identifications/comparisons, and/or photographs: Stéphanie Boucher (LEMQ); Christopher C. Grinter, California Academy of Sciences, San Francisco, CA, USA; JoVonn G. Hill, Mississippi Entomological Museum and also the current curator of the USNM melanopline collection; Sangmi Lee (ASUHIC); Brian Lotze; Daniel Otte (ANSP); K. Chris Reuter (USDA APHIS PPQ S&T); David Rentz; Scott Schell, University of Wyoming, Laramie, WY, USA; Floyd Shockley (USNM); Erika Tucker (UMMZ); Naoki Takebayashi, University of Alaska Fairbanks (UAF) Institute of Arctic Biology, Fairbanks, AK, USA; Jason D. Weintraub (ANSP); and Susan Wise-Eagle. Additionally, we thank Matt Bowser (KNWR) for writing the R mapping script, Rose Speranza for help finding the Washburn papers in the UAF Rasmuson Library Archives, and Jayce Williamson for providing feedback that greatly improved the key. We thank the Undergraduate Research and Scholarly Activity (URSA) program at UAF for providing funding to the first author in support of this study and we thank two reviewers whose comments improved an earlier version of the manuscript.
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