Bembidion lividulum Casey, 1918: 25

Sproul, John S. & Maddison, David R., 2018, Cryptic species in the mountaintops: species delimitation and taxonomy of the Bembidion breve species group (Coleoptera: Carabidae) aided by genomic architecture of a century-old type specimen, Zoological Journal of the Linnean Society 183, pp. 556-583 : 571-573

Bembidion lividulum Casey, 1918: 25 . Lectotype female, designated by Lindroth (1975: 117), in USNM, labelled ‘Placer Co. CAL.’ [white paper], ‘CASEY bequest 1925’ [white paper], ‘TYPE USNM 36830’ [red paper], ‘lividula Csy.’ [white paper, hand written], ‘ LECTOTYPE saturatum Csy. By C.H. Lindroth’ [white paper, partly handwritten]. Type locality: Placer Co., California. Examined, including DNA sequences. Extracted DNA is deposited at the USNM and associated with the GUID of the type specimen: ark:/65665/3fa4e0e6d-4705-4d96-b32b- 83af093df729.

M, specimens are microsympatric (i.e. collected at the same locality); S, specimens that are broadly sympatric, but not known to occur at the same locality. Cells with numbers indicate the distance in kilometres between the nearest confirmed localities for non-sympatric species

Nomenclatural notes: This is the species referred to as ‘ Bembidion “Ebbets Pass”’ in Sproul & Maddison (2017) and B. breve (specimen 1930) in Maddison (2012).

Diagnosis: A shiny, medium-sized, parallel-sided, relatively flat species with strongly foveate dorsal punctures ( Fig. 1A). Forebody and elytra black or dark brown often with aeneous hue. Pronotum widest anterior to middle with obtuse hind angles; not sinuate laterally; laterobasal carina strong ( Figs 11A, 12A). Elytra parallel-sided; dorsal punctures strongly foveate. Elytral disc commonly with uneven surface (caused by a depression in elytral surface) in basal third anterior to dorsal punctures (see pattern of shadows in the basal third of elytral disc in Fig. 1A). Microsculpture weakened in males ( Fig. 13B) causing shiny appearance and making foveate dorsal punctures easily visible without magnification. Male genitalia with flagellum sinuate and moderately long; sclerite ‘St’ slender, commonly hourglass-shaped ( Figs 8A, B, 10A).

Comparison with similar species: Most easily confused with B. ampliatum and B. breve . Can be distinguished from the former by having a slightly more convex pronotum and stronger laterobasal carina, more strongly foveate dorsal punctures (particularly where they cooccur with B. ampliatum in California) and unevenness in the basal third of the elytral disc anterior to the dorsal punctures, and a longer, more sinuate flagellum and more slender sclerite ‘St’. Distinguished from the latter by having more parallel-sided elytra, the pronotum widest anterior to middle and a slen- der sclerite ‘St’. May also be confused with B. laxatum from which it is distinguished by having a smaller body size, weaker microsculpture, a narrower pronotum relative to elytral width and sclerite ‘St’ lacking U-shaped recurvature.

Geographic distribution: From southern British Columbia along the Cascade Range to the southern Sierra Nevada. East through Idaho to the Rocky Mountains in Montana and southeastern British Columbia ( Fig. 14A) .

Habitat: Known from a wider range of environments than most other species in the group. It is often abundant in the damp soil below receding snow patches on alpine slopes. Also present along the shoreline of streams and lakes at high elevation. Common along the shorelines of moderate-sized rivers at somewhat lower elevation with increasing latitude (e.g. the Pacific Northwest and Alaska).

Geographic variation: This species is fairly variable across its range and within populations. Notable size variation is common in multiple locations of the Oregon Cascades and in Montana, with very small females in some populations (those sequenced do not show obvious differences in the genes examined).