Found at lights on 2nd night of the 2013 BugGuide summer gathering.

When I photographed this fly I figured it was the same as the other pyrgotid flies we were seeing that night, some of which are posted below:



However at full-size on the computer screen this one looked different...with its the strongly banded tibiae, and more "blocky" mouthparts with black palps. I initially guessed those differences might be due to sexual dimorphism within the same species. But they turned out to be different species. Working through the keys in the MND(1) and Steyskal (1978) this individual went to genus Boreothrinax, with a crucial character being the distinctively constricted basal 1/3 of the hind tibia.

The genus Boreothrinax was erected in Steyskal (1978) with three species: two were new species, B. shewelli and B. dichaetus; and the third, B. maculipennis, was moved from Sphecomyiella maculipennis (originally Oxycephala maculipennis Macquart 1846). Using the key to species in Steyskal (1978), I arrived tentatively at B. maculipennis, based on the combination of Arizona location and bare prosternum (B. dichaetus is also recorded from AZ, but has prosternum with fine lateral setae). Unfortunately the description of B. maculipennis in Steyskal is minimal so I decided to search for more info on the web.

When I checked BugGuide I found a number of images, but was surprised to see them posted under the name "Pyrgota" maculipennis, with the info page listing Boreothrinax maculipennis as a synonym. The initial BugGuide post under P. maculipennis was made in 2005 and is shown in the thumbnail below:



In that post Gary Steck (again, in 2005) made the ID of Pyrgota maculipennis, noting the shape and banded color pattern of the hind tibia, and mentioning that B. maculipennis was a synonym. A species page was made and all subsequent posts have been placed under Pyrgota maculipennis.

But why did the genus name Pyrgota get substituted for Boreothrinax here? Was there a publication sometime after the 1987 MND that had presented a basis for making B. maculipennis a junior synonym of Pyrogta maculipennis? If so, I figured that would be reflected in the more recent Manual of Central American Diptera(2) Vol 2, published in 2010. But the MCAD recognizes the same 3 US species of Boreothrinax as the MND(1) did...namely those circumscribed in Steyskal (1978), which is cited by both the MND and the MCAD as their reference for that genus (as well as the US species of Pyrgota). Other published references I searched out, like the 1996 paper here also used the name Boreothrinax maculipennis.

While I was unable to find any actual reference papers addressing whether Boreothrinax maculipennis was transferred to Pyrgota and made a junior synonym, there were numerous Google hits for the name Pyrgota maculipennis. These were principally in the form of the "web robot" type taxonomic names web sites which have proliferated in recent years (e.g. Diptera Nomenclator, ITIS, GNI, EOL, ADW, Gwannon, etc.), as well as Flickr posts and other photo posts which appeared to get the name Pyrgota maculipennis from BugGuide...perhaps in combination with the robotic taxonomy sites.

Most of the robotic taxonomy sites offer little content other than names and often seem to simply copy information from each other and lack logical consistency. For instance, the ITIS web site lists Pyrgota as a genus having 6 valid species...including the 3 species dichaetus, maculipennis, and shewelli that Steyskal put in Boreothrinax. They also include valida among those 6 Pyrgota species names, apparently referring to Sphecomyiella valida, which they also list as a valid species on their Sphecomyiella web page...so they are apparently asserting two different "valid" names for the same species! I also noticed that the ITIS Boreothrinax web page indicates Boreothrinax is a valid genus...but they show it as having no species!! Meanwhile, there is no mention on the ITIS page for Pyrgota maculipennis of the purported synonym Boreothrinax maculipennis.

Compare the situation for the ITIS listings discussed above to the BugGuide Pyrgota info page, created in 2004 (i.e. before the Pyrgota maculipennis guide page was created in 2005), which cites the now defunct Nearactica.com web site as listing just 2 species in the genus: fenestrata and undata. That agrees with the treatment in Steyskal (1978), which appears to still be valid as far as I can tell.

All this makes the names given on the "web robot" pages seem fishy...which it is consistent with the reservations expressed by various taxonomists I know regarding the accuracy of some (but not all) such listings.

So...is anyone aware of a bonafide post-1987 publication or catalog indicating that Boreothrinax maculipennis was made a junior synonym for Pyrgota maculipennis?

My guess is that, unless I'm missing something, it appears that Boreothrinax is the valid genus name here, in which case the genus name currently being used for this species on BugGuide should be corrected.