In an earlier post, I discussed the mystery of Bembidion ulkei. Here’s a quick summary: according to Lindroth’s (1963) study, Bembidion obscuripenne is a widespread species in the west, from California north to Washington. In contrast, Lindroth knew B. ulkei only from the type series of five specimens labelled “Nevada”. However, every single male that I have examined from Nevada, California, Oregon, and Washington has male genitalia that match Lindroth’s drawing of the male genitalia of B. ulkei, and none match B. obscuripenne. Lindroth’s drawing of B. obscuripenne is of a male from Dallas, Oregon, in the coastal range, and I have not seen any specimens of this group from the coastal range. There seemed to be only two viable explanations for these observations: either (1) B. obscuripenne is a rare species restricted to the Coast Range of Oregon, and B. ulkei is the widespread species, or (2) Lindroth mislabelled the figures in his publication.
I have borrowed the holotype specimens of B. obscuripenne and B. ulkei, and today I know the answer.
Holotypes are “name bearers”. When someone gives a name to a previously unnamed species, they designate one specimen as the holotype. This specimen is special in that it will be called by that name if any specimen will. It is as if it carries a flag that says “I represent the species X”, where “X” is the name.
Having a name-bearing specimen is important as later research can show that what was thought to be one species is actually composed of two distinct species, or what was thought to be two species actually belong to the same species. Taxonomic research is conducted in steps: (1) specimens are studied to determine the species that exist and the boundaries between them, without consideration for whatever name the species might be called; (2) all of the holotypes and other primary type specimens (some older names don’t have holotypes, but have equivalent specimens called lectotypes or neotypes) are examined and it is determined within which species those specimens belong; (3) if any species has a single primary type specimen contained within it, then the name that is carried by that type is the name of the species; (4) if any species has two or more primary type specimens contained within it, then, of the names carried by those types, the oldest name is the name of the species; (5) if any species has no primary type specimens contained within it, then that is an unnamed species (also called a new species or undescribed species). It can get a little more complex than this, but the normal procedure is as described.
With this in mind, I borrowed the holotype of Bembidion obscuripenne (which is stored in the California Academy of Sciences in San Francisco – thank you Dave Kavanaugh for caring for the specimen and sending it to me!), and the holotype of B. ulkei (which is housed in the Carnegie Museum of Natural History, Pittsburgh – thank you Bob Davidson for that specimen!).
As a reminder, here are Lindroth’s figures of the male genitalia of B. obscuripenne and B. ulkei:
All of the males I had examined previously have a relatively short flagellum and upturned accessory piece that matches Lindroth’s figure of B. ulkei:
And now the holotypes. First, the holotype of B. obscuripenne:
It matches all of the other specimens I had seen to date – a short flagellum and upturned accessory piece – but it does not match Lindroth’s figure of B. obscuripenne.
The genitalia of the holotype of B. ulkei looks like this:
Well, well. It has a long flagellum, and a downturned accessory piece, and looks rather like that figured by Lindroth as B. obscuripenne. In fact, a close comparison of details indicates that the specimen figured by Lindroth as B. obscuripenne is the holotype of B. ulkei.
Thus, the solution to the puzzle was the simple, boring one: Lindroth mislabelled the figures in his publication. This is how they should have been labelled:
What this means is that the widespread species should indeed be called B. obscuripenne, as Lindroth called it, and that there is a second species, B. ulkei, still currently only known from the five original specimens, which were found somewhere in Nevada. Where that was, we do not know, but perhaps we will rediscover this species on our trip there this summer.