Canadian Journal of Arthropod Identification
 
 

Orthoptera of Alaska: A photographic key, new records, and synonymy of Melanoplus gordonae

CJAI 44 -- April 23, 2021
doi:10.3752/cjai.2021.44

Adam Haberski, Derek A. Woller, and Derek S. Sikes

| Abstract | Introduction | Checklist | Materials & Methods | Taxonomy | DNA Barcoding | Species Key | Acknowledgments | References | PDF | Cite |
 
 

DNA Barcoding

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
BIN (p-dist)
Distance to nearest neighbor (p-dist)
Aeropedellus arcticus UAMIC601-13 UAM UAM:Ento:103041 ACE7981 5 0.77% 1.14%
Arphia conspersa UAMIC582-13 UAM UAM:Ento:84141 AAD7721 26 2.01% 1.61%
UAMIC589-13 UAM UAM:Ento:96690 AAD7721 26 2.01% 1.61%
Camnula pellucida UAMIC3719-19 UAM UAM:Ento:146222 AAA8764 117 2.41% 5.87%
UAMIC3733-19 UAM UAM:Ento241070 AAA8764 117 2.41% 5.87%
UAMIC3736-19 UAM UAM:Ento312305 AAA8764 117 2.41% 5.87%
UAMIC3738-19 UAM UAM:Ento340665 AAA8764 117 2.41% 5.87%
UAMIC590-13 UAM UAM:Ento:96692 AAA8764 117 2.41% 5.87%
UAMIC591-13 UAM UAM:Ento:96696 AAA8764 117 2.41% 5.87%
Chloealtis abdominalis UAMIC3729-19 UAM UAM:Ento:340655 AAC8496 21 0.52% 6.19%
UAMIC607-13 UAM UAM:Ento:106209 AAC8496 21 0.52% 6.19%
UAMIC608-13 UAM UAM:Ento:106211 AAC8496 21 0.52% 6.19%
Melanoplus borealis UAMIC711-13 UAM UAM:Ento:119366 AAA4555 1896 6.78% 1.11%
UAMIC712-13 UAM UAM:Ento:119367 AAA4555 1896 6.78% 1.11%
Melanoplus fasciatus UAMIC585-13 UAM UAM:Ento:92935 AAA4555 1896 6.78% 1.11%
UAMIC586-13 UAM UAM:Ento:92936 AAA4555 1896 6.78% 1.11%
Melanoplus sanguinipes UAMIC605-13 UAM UAM:Ento:106207 AAA4555 1896 6.78% 1.11%
UAMIC606-13 UAM UAM:Ento:106208 AAA4555 1896 6.78% 1.11%
Pristoceuthophilus cercalis UAMIC710-13 UAM UAM:Ento:116244 AAG2718 42 3.54% 7.73%
UAMIC836-13 UAM UAM:Ento:214244 AAG2718 42 3.54% 7.73%
Pseudochorthippus curtipennis UAMIC578-13 UAM UAM:Ento:71788 ACL2935 1 N/A 3.88%
Stethophyma grossum UAMIC1077-13 UAM UAM:Ento:85002 AAI0053 15 1.09% 4.17%
Tetrix brunnerii UAMIC3714-19 UAM UAM:Ento:142469 AAG2982 54 1.16% 9.62%
UAMIC3734-19 UAM UAM:Ento:261755 AAG2982 54 1.16% 9.62%
UAMIC3744-19 UAM UAM:Ento:365660 AAG2982 54 1.16% 9.62%
UAMIC699-13 UAM UAM:Ento:106212 AAG2982 54 1.16% 9.62%
Tetrix subulata UAMIC3716-19 UAM UAM:Ento:320868 AAY6671 10 0.32% 1.92%
UAMIC3723-19 UAM UAM:Ento:313776 AAY6671 10 0.32% 1.92%
UAMIC3725-19 UAM UAM:Ento:167743 AAY6671 10 0.32% 1.92%
UAMIC3740-19 UAM UAM:Ento:313803 AAY6671 10 0.32% 1.92%
UAMIC3741-19 UAM UAM:Ento:321926 AAY6671 10 0.32% 1.92%
UAMIC3742-19 UAM UAM:Ento:323142 AAY6671 10 0.32% 1.92%
UAMIC3747-19 UAM UAM:Ento:313804 AAY6671 10 0.32% 1.92%
UAMIC3750-19 UAM UAM:Ento:365088 AAY6671 10 0.32% 1.92%
UAMIC3753-19 UAM UAM:Ento:323161 AAY6671 10 0.32% 1.92%
UAMIC573-13 UAM UAM:Ento:15722 ACJ7497 1 N/A 2.41%