Celticecis spiniformis

Cecidomyiaceltis spiniformis
Cecidomyia unguicola New synonym.
Celticecis unguicola

Hosts. Celtis occidentalis, reticulata, laevigata, tenuifolia

Gall. On leaf lamina, usually on underside of leaf, often in groups; upright-conical; base flared, circular, flat to rounded; tapering evenly from base to sharply pointed apex; surface hairless, glabrous, green, turning yellow to tan; 4–6 mm high and 3–4 mm wide at base; connection to leaf circular, flat, ca. 1/3 width of gall base; apparent on opposite side of leaf as slight, sometimes discolored convexity; gall in cross section of variable thickness beneath and around base of subcylindrical larval chamber, thinning abruptly between distal third and fourth, at which level gall apex breaks off upon adult emergence in spring.

Affinities. — Nine species of Celticecis appear to form a natural group: C. spiniformis, C. aciculata, C. acuminata, C. capsularis, C. conica, C. cupiformis, C. pilosa, C. subulata, and C. supina. All form galls on the leaf lamina except for C. supina whose galls are attached to veins, usually minor ones.

Biological notes. Galls reach their ultimate length as a narrow cone before the base broadens to its full width, so young galls can at first be confused with those of C. subulata. The gall only later spreads out considerably at the base, which can be acute to well-rounded in cross section. When full-grown, the larva spins a cocoon that extends only to the narrow part of the larval chamber where the tip of the gall will break off in spring. Galls were already evident in late March in central Louisiana on only partly expanded leaves and were first noticed already with second instars in early May in Maryland. At least some full-grown larvae had already formed cocoons in mid-June in Louisiana and late June in Maryland. Many galls still with second instars can be found through mid-July so growth appears staggered. Some galls with cocooned larvae may remain attached to the leaves into September in Maryland and into November in Louisiana where the leaves remain on the tree longer. This longer duration on the leaves is a habit shared by most of the nine species of the C. spiniformis group, unlike most galls of the remaining species that tend to dehisce as soon as the larvae have formed their cocoons.

Distribution (Map 18). — Celticecis spiniformis is a common, widespread species in the eastern half of the U.S., except in Florida where it is conspicuously absent. It is known from northern hackberry, sugarberry, dwarf hackberry and reticulated hackberry.

AR, GA, IL, IO, KS, KY, LA, MD, MS, MO, NY, OH, PA, SD, TN, TX, VT, VA, WV, WI; absent in FL

Celticecis spiniformis New Combination

Cecidomyiaceltis spiniformis

Celticecis unguicola New Combination

Cecidomyia unguicola

Celticecis spiniformis

In this study, C. spiniformis was found at all four study sites in Pennsylvania, at the two New Jersey study sites, and at the two study sites in New York (Figure 9). This study expands the range of C. spiniformis into New Jersey, representing a new state record for this species.

[No name given; later named Cecidomyiaceltis spiniformis by Patton]

34. Cecidomyidous galls on the under side of the leaf, either singly or in smaller or larger numbers, usually between the leaf-veins, rarely crossing the large ribs. The gall is a more or less stout conical spine arising from a circular base, and either gradually and regularly tapering toward the tip or more suddenly narrowed a short distance from the base, and then with the sides more vertical; tip more or less acute and often slightly curved. Color pale yellowish, surface a little shining, either without distinct sculpture or with faint longitudinal furrows, especially near the base. Average height, 4 mm; average diameter at base, 2.8 mm. The walls of the gall are thin except near the base, where they are thicker; the cell is elongate ovoid, and extends from the base to the tip of the spine. On the upper side of the leaf the gall is visible as a small circular slightly depressed spot of pale color and furnished in the center with a small nipple. While issuing, the perfect insect pushes off the tip of the spine.

Cecidomyia spiniformis

Conical, spine-shaped leaf gall on the under surface and arising from a circular, yellowish base, height 4 mm, diameter 2.8 mm.

Cecidomyia unguicula

Subconical leaf gall, clustered on the under surface, length 3 to 5 mm.

Cecidomyia unguicola sp. nov.

Gall.--Somewhat of the shape of a small carpet-tack with the broad part attached to the leaf. The base is rounded at the sides, from which it suddenly becomes narrow, terminating in a sharp point at the apex. Inside it is hollow and contains a single larva. Found in clusters on the under side of the leaf of hackberry (Celtis occidentalis). Length about 3 to 5 mm; width of base about 2 to 3 mm.

Habitat: OH

Cecidomyia unguicola

On leaf, under side, a, sharply pointed cone-shaped gall with flaring base. 3-5 mm. high, 2-3 mm. wide. Light green to yellow in color. Smooth, almost shining. Monothalamous, rarely, if ever confluent. Chamber sub-cylindric, with the distal half thinner walled than the proximal. The distal one- third or one-fourth of the gall is delimited proximally by the sudden transition from delicate sub-hyaline tissue to opaque hard tissue. Sooner or later the tip breaks off at this point. Riley states that "while issuing the perfect insect pushes off the tip." This gall is the most common of all the itonid galls of the hackberry; a hundred may often be found upon a single leaf.