Sympistis riparia (Morrison) Troubridge, J. T., 2008

Troubridge, J. T., 2008, A generic realignment of the Oncocnemidini sensu Hodges (1983) (Lepidoptera: Noctuidae: Oncocnemidinae), with description of a new genus and 50 new species, Zootaxa 1903 (1), pp. 1-95 : 29

The Sympistis riparia group

The Sympistis riparia group includes Sympistis riparia (Morrison) comb. n., S. nenun sp. n., S. chons sp. n., S. mut sp. n., S. amun sp. n., S. richersi sp. n., Sympistis aqualis (Grote) comb. n., Sympistis deserticola (McDunnough) comb. n., stat. n., and Sympistis major (Grote) comb. n.. Although external differences between many of the species are subtle and genital differences often non-existent, DNA analysis gave significant differences between species of the S. riparia group, confirming what the subtle morphological data suggested. The COI sequence data placed S. nenun and S. riparia as the most similar species within the group, with a 1.87% difference between the two species. Differences between other species were more greater, for example, S. deserticola vs. S. amun was 4.74%; S. deserticola vs. S. major was 5.29%; S. major vs. S. chons was 2.89%; S. deserticola vs. S. mut was 5.82%; S. riparia vs. S. major was 3.71%, and S. chons vs. S. riparia was 4.39%.

Most species of the S. riparia group exhibit significant individual and geographic variation with little or no genitalic differences between species, making positive identification difficult. By using wing markings in combination with distribution and habitat, most specimens can be identified with some certainty. The forewing of S. riparia has a soft, satiny appearance, antemedial and postmedial lines may or may not be present, and the pale subterminal line is present as a series of pale dots or an undulating line (Figs. E-2, E-3). It occurs in dune systems from central Alberta to the Atlantic coast of New England and the Maritime Provinces. Throughout its range, the forewing of S. major is consistent in that the orbicular, reniform, and particularly the claviform spots are distinctly highlighted with white scales, the subterminal line is deeply denticulate, and white scales often border a series of black subterminal dashes (Figs. D-13, D-14). It occurs in desert habitats, usually sandy, from western Colorado, west to southern California, where it has been collected with S. deserticola in Inyo Co.. The forewing of S. deserticola is similar to that of S. major , but with a blacker ground color. The hindwing is white with a narrow (2-3 mm) dark gray marginal band (Fig. D-12), that of S. major is light grayish brown with a wider, less sharply defined, dark grayish brown marginal band (Figs. D-13, D-14). Sympistis deserticola occurs in the deserts of southern California. Based on the phenotyic and molecular differences, and the fact that the two taxa remain distinct in sympatry, deserticola is raised to species status. The forewing of S. aqualis is distinctive with a prominent black basal dash and thin black lines through the postmedial area (Fig. D-9); there are often a few white scales bordering these lines. It has been collected in the deserts of San Bernardino Co., California and adjacent Clark Co., Nevada. Sympistis sala Mustelin syn. n. is a synonym of S. aqualis (Fig. D-9).