Caryomyia flaticrustum Gagne, new species

Hosts: Carya ovata, tomentosa, glabra, laciniosa, texana, pallida

Gall (Figs. 16a, 78-81): Common, on Eucarya hickories; on lower leaf surface between veins, usually clustered; 2-4 mm in height, usually longer than wide, conical to cylindrical, deeply concave apically, walls encircling concavity flared outwards, cylindrical, or ingrown toward apex as to form nearly complete false chamber, base of concavity with short central umbo; green at first, drying to tan or brown, walls surrounding concavity soft, eventually turning mucilaginous and contracting to form circular brown crust atop basal portion of gall; leaf with only slight exfoliation surrounding conical base of gall; lateral wall of larval chamber firm, brittle, thin apical wall usually thicker, larval chamber glabrous, with longitudinal ridges. When dried this gall simulates that of C. melicrustum but the gall of the latter is surrounded basally with an extensive, thick leaf exfoliation.

Affinities. — Caryomyia flaticrustum, C. levicrustum, C. melicrustum, and C. striolacrustum are four common, widely distributed species on the Eucarya section with diminutive, more or less discoid galls with conical bases (Figs. 78-87). The main differences among the four species are in the shape and surface texture of the galls. That of C. flaticrustum, has a soft, sticky, concave apex that eventually contracts to form a thick crust. These mature galls simulate somewhat galls of C. melicrustum, except that galls of the latter are subtended by a definite exfoliation of the leaf. Larvae of all four species are generally similar with a fairly smooth integument and cruciform spatula. The spatula tooth is barely notched in three species, but acutely pointed in C. levicrustum.

Range: AL, AR, CT, FL, GA, IL, IN, KY, ME, MD, MA, MO, MS, MO, NH, NJ, NY, NC, OH, OK, PA, SC, TN, TX, VA, DC, WV

- Raymond J. Gagne: (2008) The Gall Midges (Diptera: Cecidomyiidae) of Hickories (Juglandaceae: Carya)^©

Reference: https://www.biodiversitylibrary.org/page/38636615#page/46/mode/1up