Bembidion corgenoma, Maddison, 2020

Maddison, David R., 2020, Shards, sequences, and shorelines: two new species of Bembidion from North America (Coleoptera, Carabidae), ZooKeys 1007, pp. 85-128 : 85

Bembidion corgenoma sp. nov.

Holotype.

Male, in OSAC, labeled: "USA: Oregon: Benton Co., Corvallis, Willamette River, 60 m, 44.5491°N, 123.2449°W, 7.x.2019. DRM 19.210. D.R. Maddison", "David R. Maddison DNA5673 DNA Voucher" [pale green paper], "HOLOTYPE Bembidion corgenoma David R. Maddison" [partly handwritten, on red paper], "Oregon State Arthropod Collection OSAC_0002000008 [matrix code]" [printed on both sides of white paper]. Genitalia mounted in Euparal in between coverslips pinned with specimen; extracted DNA stored separately. GenBank accession numbers for DNA sequences of the holotype are MW151449, MW151463, MW151491, MW151520, and MW151548.

Paratypes

(193). USA: Oregon: Benton Co., Corvallis, Willamette River, 44.5491°N, 123.2449°W, 60 m [type locality] (78: OSAC, CNC, CAS, UAIC, UASM, MCZ, EMEC, CSCA); USA: Oregon: Benton Co., Corvallis, Willamette River, 60 m, 44.5491°N, 123.2451°W (10: OSAC); USA: Oregon: Benton Co., Corvallis, Willamette River, 44.5475°N, 123.2428°W, 60 m (35: OSAC, USNM, NHMUK, MNHM, UBCZ); USA: Oregon: Benton Co., Corvallis, Willamette River, 60 m, 44.5478°N, 123.2430°W (2: OSAC); USA: Oregon: Benton Co., Corvallis, 62 m, 44.5491°N, 123.2449°W (6: OSAC); USA: Oregon: Linn Co., Willamette River, Truax Island, 44.5853°N, 123.1913°W, 60 m (12: OSAC); USA: Oregon: Lane Co., Goodman Creek, Willamette NF, 43.8441°N, 122.6736°W, 290 m (2: OSAC); USA: Oregon: Coos Co., Crooked Creek S of Bandon, 43.0814°N, 124.4335°W, 7 m, 24.iii.2014 (26: OSAC); USA: California: Tehama Co., Red Bluff, Sacramento River, 40.1759°N, 122.229°W, 73 m (22: OSAC, CAS, EMEC).

Type locality.

USA: Oregon: Benton Co., Corvallis, Willamette River, 44.5491°N, 123.2449°W.

Derivation of specific epithet.

The specific epithet is formed from the Latin word cor, meaning heart, and genoma, a modification (for easier pronunciation) of the coined word “genome”. Corgenoma refers to this species being the heart or current focus of genomic studies in small carabid beetles. Cor - also alludes to the type locality of Corvallis, Oregon, whose name is derived from Latin, and means "heart of the valley". It is to be treated as a noun in apposition.

Diagnosis and description.

Length (5.8-7.4). Relatively light in color compared to B. transversale and B. erosum , with legs and basal three antennomeres pale, testaceous or rufo-testaceous. Head and prothorax piceous, with metallic reflections, on pronotum green or aeneous, on head bluish or green. Elytra paler, with shoulders and most of the anterior half testaceous with an orange tint, bordered posteriad by a dark band (with intervals 1-3 in this region dark rufous), followed by a pale testaceous band that either extends to the apex or that is bounded posteriad by dark lateral spots which in the darkest individuals merge in the middle. Mentum with anterior lateral region as typical for a Bembidion : triangular, large, and with anterior margin significantly anteriad of the central tooth (Fig. 13A ); central tooth trapezoidal, rounded. Prothorax cordate, with more sinuate margins than B. perspicuum , with a relatively smooth basal region, with minute punctures; pronotum without or with very faint, oblique posterolateral carina as in other members of this group. Elytral striae 1-5 complete; stria 6 distinct and strong through much of its length; stria 7 shallower, less impressed than 6, but distinct. Microsculpture of elytra very transverse, with little tendency to form meshes. Two discal setae on each elytron, close to third stria. Tip of aedeagus not abruptly curved downward (Fig. 14E, F ); basal sclerotized lobe small (Fig. 15C ); apex of flagellar sheath with dark area triangular (Fig. 16E, F ).

Additional characteristics.

Diploid chromosome number 24, with 11 pairs of autosomes and an XY/XX sex chromosome system ( Pflug, et al. 2020). Genome size (1C), as measured by flow cytometry, 2118 Mb in males and 2193 Mb in females ( Pflug, et al. 2020). Most specimens with singleton (non-conjugated) sperm ( Gómez and Maddison 2020).

Available genomic and transcriptomic data.

Transcriptomic data for one specimen is available on NCBI’s Sequence Read Archive at accession SRR8801541, and genomic data of four specimens at accessions SRR8518612, SRR8518625, SRR8518626, and SRR8518631 ( Pflug, et al. 2020).

Notes.

This species was called Bembidion haplogonum Chaudoir in Gustafson et al. (2019; 2020), and B. sp. nr. transversale in some other publications ( Gómez and Maddison 2020; Kanda, et al. 2015; Pflug, et al. 2020).

Geographic distribution.

This species occurs from central British Columbia south through the Willamette Valley of Oregon, the Central Valley of California, with some records in Nevada, Idaho, eastern Washington, and Montana (Fig. 19 ), thus overlapping with the range of B. transversale .

Geographic variation.

The specimens on or close to the beaches of the Pacific Ocean appear on average slightly paler than more inland specimens.

Habitat.

This species occurs on gravel or cobble shores of the rivers and creeks (Fig. 4 ), more often where the bank is relatively flat and has small amount of clay and silt mixed in with sand and gravel under the rocks. They also can be common under cobbles on the shores of small creeks on the upper portions of beaches of the Pacific Ocean.

Figures

Figure 4. Habitats of Bembidion corgenoma A USA: Oregon: Benton Co., Corvallis, Willamette River, 60 m, 44.5491 ° N, 123.2449 ° W (type locality). B. corgenoma and B. recticolle are both common in this habitat. B. corgenoma is more common near the water in areas with vegetation growing nearby among the gravel and cobbles B USA: California: Del Norte Co., Wilson Creek, 3 m, 41.6051 ° N, 124.1005 ° W, habitat of B. corgenoma and B. erosum, as well as Bembidion haruspex Casey, B. vandykei Blaisdell, B. curtulatum Casey, B. platynoides Hayward, and B incrematum LeConte.

Figure 13. Mentum of B. corgenoma and B. transversale A Two specimens of B. corgenoma from Corvallis, Oregon B Two specimens of B. transversale from Hayden Lake, Idaho C Two specimens of B. transversale from Wallowa State Park, Oregon D Two specimens of B. transversale from Point aux Pins, Michigan.

Figure 14. Male genitalia of B. transversale subgroup A B. transversale (voucher DNA 4219, USA: Oregon: Harney County, Banks of Silver Creek, 1379 m, 43.7278 ° N, 119.6256 ° W) B B. transversale (voucher DNA 2161, Canada: Alberta: Lethbridge, Oldman River, 800 m, 49.7043 ° N, 112.866 ° W) C B. erosum (voucher DNA 4033, USA: Oregon: Curry Co., Floras Creek at route 124 SE Langlois, 21 m, 42.9132 ° N, 124.4251 ° W) D B. erosum (voucher DNA 3562, USA: California: Del Norte Co., Wilson Creek, 3 m, 41.6051 ° N, 124.1005 ° W) E B. corgenoma (voucher DNA 2180, USA: California: Sonoma Co., Russian River, 3 mi NE Healdsburg) F B. corgenoma (holotype, voucher DNA 5673, USA: Oregon: Benton Co., Corvallis, Willamette River, 60 m, 44.5491 ° N, 123.2449 ° W). Scale bar: 0.1 mm.

Figure 15. Basal sclerotized lobe of internal sac of male Bembidion transversale group members A B. transversale (voucher DNA 4219, USA: Oregon: Harney County, Banks of Silver Creek, 1379 m, 43.7278 ° N, 119.6256 ° W) B B. erosum (voucher DNA 4033, USA: Oregon: Curry Co., Floras Creek at route 124 SE Langlois, 21 m, 42.9132 ° N, 124.4251 ° W) C B. corgenoma (voucher DNA 2180, USA: California: Sonoma Co., Russian River, 3 mi NE Healdsburg). Scale bar: 0.1 mm.

Figure 16. Central sclerite complex of B. transversale subgroup A, B B. transversale (vouchers V 101437 and V 101436, USA: Michigan: Port aux Pins, Bois Blanc Isl.) C, D B. erosum (vouchers V 101440 and V 101439, USA: California: Del Norte Co., Wilson Creek, 3 m, 41.6051 ° N, 124.1005 ° W) E, F B. corgenoma (vouchers V 101428 and V 101430, USA: Oregon: Benton Co., Corvallis, Willamette River, 44.5475 ° N, 123.2428 ° W). Scale bar: 0.1 mm.

Figure 19. Geographic distribution of B. transversale and B. corgenoma (eastern portion of distribution of B. transversale not shown).