Eornithoica grimaldii sp. nov.

(Fig. 1) urn:lsid:zoobank.org:act: 6234ECDE-4652-4FA1-9A6D- F765A993D8D8

Holotype. FOBU17740 (part and counterpart of a complete fly), deposited in the collection of Fossil Butte National Monument, Wyoming, USA.

Etymology. The specific epithet is dedicated to Prof. Dr David A. Grimaldi, in recognition of his impressive contributions to the study of fossil insects and extant Diptera.

Diagnosis. As for the genus (vide supra).

Type locality and horizon. Douglass Pass, Garfield County, Colorado, USA, Early Eocene, Green River Formation, Parachute Creek Member, Ypresian, 46.2– 40.4 Ma.

Description. Body ca. 7.0 mm long, as preserved, dark brown, covered with numerous stout spines and spurs; head poorly preserved, detached from thorax but originally deeply inserted between fore legs, ca. 1.2 mm long, 1.0 mm wide, with mouthparts projected forward; compound eyes in lateral positions; ocelli not visible, apparently absent. Thorax 3.1 mm long, 2.1 mm wide; thoracic segmental borders indistinct dorsally, but not completely obliterated; procoxae widely separated, with a large, distinctly less-sclerotized area between them; protergum distinctly shortened; mesothorax wider than long; mesocoxae widely separated; metacoxae widely separated; wings normally developed, 6.4 mm long, ca. 2.3 mm wide, slightly shorter than body; R1 short; R2+3 longer than R1, reaching wing midlength; R4+5, M1+2, and M3+4 long; crossveins r-m and i-m present but faint; R4+5 reaching wing margin distally with a broad cell between R2+3 and R4+5; eight long and stout spurs on costal margin; numerous strong spines/spurs on legs; procoxa inflated, greatly enlarged; tarsomeres I longer than tarsomeres II to IV, the latter distinctly shortened and compact; pretarsal claws recurved, not bifid, with a conspicuous base or heel; at least apex of mesotibia with a row of five stout spurs; mesofemur stout, as long as mesotibia; abdomen 3.0 mm long, 2.9 mm wide, covered with numerous long, stout spines/spurs, some situated on enlarged sclerotized bases; three large transverse dorsal sclerotized plates on basal-most segments.

Remarks. It is impossible to determine what host might have been visited by the present fossil, but given that basal hippoboscids are typically ectoparasitic on birds, it is likely that E. grimaldii was specialized for some extinct species of Aves. The bird fauna of the Green River Formation is rather diverse and certainly harbored any number of potential hosts for these flies (Weidig, 2010), but fossil bats are also present in this formation (Jepsen, 1966).