Brachinus imperialensis Erwin, 1965

Erwin, Terry L., 1965, A Revision Of Brachinus Of North America: Part I. The California Species (Coleoptera: Carabidae), The Coleopterists Bulletin 19 (1), pp. 1-19 : 17

Brachinus imperialensis Erwin , NEW SPECIES

TYPE LOCALITY: Potholes , Imperial County, California.

TYPE SPECIMENS: The holotype male and allotype female have been deposited in the entomological museum at the California Academy of Sciences in San Francisco. Both were collected by E. P. Van Duzee at the type locality, on April 9, 1923. Eighteen paratypes collected on various dates and at various localities are indicated in the CALIFORNIA LOCAL- ITY RECORDS and they have been returned to the museums also indicated there.

DISTRIBUTION: This species is restricted to desert habitats along the Colorado River and outlets of the Salton Sea in Imperial County ( fig. 17 ).

DESCRIPTION: Size. Length 9 to 10.5 mm.; width 4 to 4.1 mm. Coloration. Elytra of both sexes blue with a violeceous cast and with epipleura blue; head and pronotum ferrugineus; mandibles piceous at tips and on mesal edges; antennal segment 1 ferrugino-testaceous; antennal segments 2-11, legs, palpi, and frons ferrugineus; mesepisterna and venter ferrugineus; sides of abdominal sterna black. Head. Labrum slightly emarginate; dorsal surface of the mentum convex with a seta arising at each anterior corner; bead around eyes very weak; frons with deep frontal furrows which are somewhat rugose; numerous setae arise behind eyes and a few from top of the head; microsculpture consists of small isodiametric meshes. Pronotum. Widest just before middle and with sides moderately sinuate; anterior angles prominent, finely acute, with lateral basal impressions moderately deep; lateral margins narrow with a dark lateral bead; disc slightly convex, barely rugose down midline; sparsely pubescent at base and at anterior corners; microsculpture consists of finely isodiametric meshes. Elytra. Male elytra truncate, sides almost parallel, but narrowing slightly toward humeri which are not at all prominent; barely costate; microsculpture consists of small isodiametric meshes; pubescence sparsely covering elytra, occurring in all intervals. Female elytra similar, but proportionately slightly wider than those of male in apical third. Aedeagus ( fig. 8 ). Phallus asymmetrical, ending in a rounded point; with apical third twisted considerably; microsculpture lacking. Endophallus bears a poorly pigmented virga consisting of two lateral basal lobes, which are fused apically.

CALIFORNIA LOCALITY RECORDS: 18 paratypes were examined. Imperial County: (Potholes) CAS, (Yuma) CAS, (Palo Verde) UIM, (Holtville) CAS, (El Centro) CAS, (Brawley) CAS, (Calipatria) CAS, (Calexico) ATM; Riverside County: (Blythe) CAS; San Bernadino County: (Needles) CAS.

DERIVATION OF THE NAME: Imperial County-the place the types were collected; Latin, ensis-denoting place, locality or country.

DISCUSSION: Members of this species are very similar to their more western counterpart, B. favicollis , but they lack the strong punctations and the pubescence. Also, the elytra are scarcely costate in B. imperialensis . The alkali river bank habitat of this species is quite different from the run-off stream environment of B. favicollis .

Figures

FIGURES 14-17, Brachinus spp. California distribution maps.

FIGURES 1-9, Brachinus spp. Aedeagus from dorsal and