Bembidion transversale Dejean, 1831

Maddison, David & Swanson, Alexander, 2010, A preliminary characterization of Bembidion perspicuum LeConte, with a reclassification of related species (Coleoptera, Carabidae) north of México, ZooKeys 43 (43), pp. 15-31 : 26-27

Bembidion transversale Dejean, 1831

Bembidium transversale Dejean, 1831:110 . Type locality restricted to Nipigon, Ontario, by Lindroth ( Lindroth 1963). Holotype female, in MNHN, examined by Kipling Will, who provided to us photographs, including of the mentum, allowing us to confirm the identification.

Peryphus eros Motschulsky, 1850:10 . Type locality California. Lectotype, designated by Bousquet and Larochelle (1993), in ZMUM. Synonymy tentative.

Ochthedromus mannerheimii LeConte, 1852:190 . Type locality San Diego, California. Three specimens in the MCZ in the Bembidion transversale unit tray in the LeConte collection have gold discs (signifying California), and include syntypes for this name. The first specimen is a female labeled as follows: [gold dot] / “ O. mannerheimii Lec. S. D. transversale ‡ Man” [in LeConte’s handwriting] / “transversale 27” [handwritten], and is certainly a syntype. The two following specimens, a male and female, are labeled with a gold dot in addition to a label of “transversale 28” and “transversale 29” respectively, and are quite possibly also syntypes. As the first specimen is the only one that is surely a syntype, it is herein designated as the lectotype, MCZ type number 35571. All specimens externally match the western form (see below) of B. transversale . We have examined the aedeagus of the male, and it matches that of B. transversale .

Bembidium haplogonum Chaudoir, 1868: 241 . Type locality California. Location of types unknown. Synonymy tentative.

Bembidion marinicum Casey, 1918:57 . Type locality Marin County, California. Holotype female in USNM (type number 36919), examined. Synonymy tentative.

Bembidion tuolumne Casey, 1924:30 . Type locality Tuolumne, California. Lectotype male, designated by Lindroth (1975), in USNM (type number 36917), examined. Synonymy tentative.

As currently conceived, this species is a mix of different forms. The typical form (including the holotype of B. transversale Dejean , and all specimens sequenced for this study) has an unusual mentum with much-reduced lateral lobes, which do not project anteriorly much beyond the mental tooth ( Fig. 5A ). This form occurs from Nova Scotia west to Alaska, south through eastern British Columbia, eastern Oregon, Idaho, Nevada, Utah, Colorado, and Wyoming. Western British Columbia, western Oregon, and California contain another form, with no consistent differences in COI or 28S from the typical form (Maddison, unpublished), with a normal B. transversale pronotum and aedeagus, but with full lateral lobes on the mentum. The mentum of this western form is thus similar to that of B. perspicuum , Fig. 5B , and in contrast to eastern B. transversale . The western form itself is rather variable morphologically, and is being examined in more detail (Maddison, in prep.). It may be a complex of multiple species, and thus the five younger names mentioned above are only tentatively synonymous with B. transversale . In addition, while it is clear that the LeConte name and the two Casey names are not synonyms of B. perspicuum , the Motschulsky and Chaudoir names might be junior synonyms of B. perspicuum ; examination of the types will be required to confirm the synonymies.

Morphological characters distinguishing these species from B. perspicuum are described above, under “Morphological Differences”.

Figures

Figure 5. Mentum, ventral view. Both specimens from USA: Colorado: Fremont Co., Arkansas River at Texas Creek, 38.4106°N 105.5844°W. A B. transversale, DRM Voucher V100555 B B. perspicuum, DRM Voucher V100556.