Euschistus tristigmus ( Say, 1831a )

Rider, David A. & Swanson, Daniel R., 2021, A distributional synopsis of the Pentatomidae (Heteroptera) north of Mexico, including new state and provincial records, Zootaxa 5015 (1), pp. 1-69 : 20

Euschistus tristigmus ( Say, 1831a)

New state record: Alabama: Conecuh Co.: 1.7 mi. S jct. U.S. Hwys. 31 & 84, 13-IX-1954, T. H. Hubbell & I. J. Cantrall, #103 (1♂ UMMZ) . Lee Co.: Auburn , 17-VIII-1983, J. A. Moore (1♂ DAR) ; 0.3 mi. S Co. 26, 0.1 mi. W US 29, 6-VII-1982, D. A. Rider (1♀ DAR) ; [no specific locality], 21-VI-1981, D. A. Rider (1♂ DAR) , 11-X-1981, D. A. Rider (1♀ DAR) .

Distribution: Canada: AB ( Maw et al. 2000), BC ( Maw et al. 2000), MB ( Criddle 1921, Walley 1929, Maw et al. 2000), NB ( Brown 1941, Morris 1972, Maw et al. 2000, Roch 2020), NF ( Maw et al. 2000, Roch 2020), NS, ON, PE ( Maw et al. 2000, Roch 2020), QC, SK ( Maw et al. 2000). United States: AL, AR ( Tugwell et al. 1973, Barton & Lee 1981, Chordas et al. 2005, Skvarla et al. 2016), CO, CT ( Walker 1867; Parshley 1917, 1923a; Britton 1920; McPherson 1976a; O’Donnell & Schaefer 2012), DC, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD ( Uhler 1876, Van Duzee 1917, Brown & Bahr 2008), ME, MI, MN, MO, MS ( Ashmead 1895, Lago & Testa 2000), NC, ND ( Hussey 1922, Rider 2012), NE, NH, NJ, NY, OH, OK, PA, RI ( Parshley 1917), SC, SD ( Parshley 1922, Harris 1937, Morihara & Balsbaugh 1976), TN ( Lambdin et al. 2003, Vlach et al. 2010), TX ( Stål 1872, Uhler 1876, Barber 1906, McPherson & Sites 1989), UT ( Knowlton & Harmston 1940), VA, VT ( Parshley 1917, 1920; Roch 2020), WA ( Zack et al. 2012), WI ( Stål 1872; Malloch 1919; Williams 2004, 2015). ( Mexico, Guatemala)

Comments: This species, commonly called the dusky stink bug, has also traditionally been split into two subspecies. The nominate form (with humeral angles acute) is more southern in distribution while the form luridus (humeral angles rounded) is more northern. Similar to Euschistus servus , these two forms appear to be broadly sympatric with numerous intermediates in the area of overlap; also the studies by McPherson (1974, 1975, 1976a) and McPherson & Vangeison (1975) have shown that the form of the humeral angles may be controlled by environmental factors (e.g., day length). In our opinion, this does not fit our definition of a subspecies. We prefer to recognize this taxon as a single species with northern and southern forms. Furthermore, Uhler (1861), Van Duzee (1904), and Rolston (1974) treated both forms as synonyms. This species has been recorded from Alabama and Wisconsin in an unpublished thesis ( Simons 1969), and also from Oregon in another unpublished thesis ( Wetherill 2000). The Colorado record ( Osborn 1893) has been queried ( Gillette & Baker 1895), and no one since has provided a record from Colorado. On the other hand, there seems to be no reason to exclude the Colorado record as this species has been recorded in all directions from Colorado.