Lionepha osculans, (CASEY, 1918), 2638

LIONEPHA OSCULANS ( CASEY, 1918) View in CoL

( FIGS 3A, 17A, B, 13A, B; 19A, 24A)

Bembidion osculans Casey, 1918: 20 View in CoL . Lectotype ♀, designated by Lindroth (1975: 116), in USNM (type # 36816), examined. Type locality: Marin County, California, as restricted by Lindroth (1963).

Bembidion speculum Casey, 1918: 20 View in CoL . Lectotype ♀, designated by Lindroth (1975: 116), in USNM (type # 36815), examined. Synonymy established by Lindroth (1963). Type locality: Marin County, California.

Diagnosis: This is the largest species of Lionepha , with some females reaching nearly 6 mm in length. It is also the broadest, with a wide, rounded prothorax ( Fig. 3A). The elytral microsculpture is more transversely stretched than other Lionepha ( Fig. 17A, B), yielding a notable iridescence, especially in the males. Elytra with at least the third stria visible beyond the posterior dorsal puncture and the second stria almost reaching the elytral apex. It tends to be slightly darker, with darker legs, than other members of the L. osculans group, but some specimens are paler. Aedeagus deep, with a bulbous appearance because of the sinuate ventral surface ( Fig. 13A, B).

Additional characteristics: Body length 4.68– 5.90 mm. Antennae dark, piceous, although the first antennomere can be dark rufous on the underside. Legs in most specimens rufopiceous, occasionally rufous, darker at the joints. Hind wings full-sized. Chromosomes of male 24 + X ( Table 5).

Geographic variation: The six specimens sequenced from Oregon have three unique bases within the 28S gene; this is evident in the 28S tree in Figure 5, where the Oregon specimens form a distinct clade .

Note: Hering (1998) reported on the food consumed by ‘ Bembidion osculans ’ on Knowles Creek in Oregon; we examined a selection of specimens from his study, and the majority belong to Lionepha tuulukwa , with a few specimens belonging to L. osculans

Distribution: A widespread species, common in the Sierra Nevada and coastal areas of California, north to Washington and Idaho ( Fig. 24A). As noted by Erwin & Kavanaugh (1981), the record from the Olympic Peninsula in Washington is somewhat doubtful. Commonly encountered between 0 and 2000 m, with a few specimens found up to 2400 m. Found in all months of the year except February; most common in the middle of summer.

Habitat: By far the commonest large Lionepha , found in a variety of habitats associated with water, including along the shores of creeks, especially in forests and on the edge of melting snowfields in open conifer forests in the Sierra Nevada.