Celticecis semenrumicis (Patton)

Cecidomyiaceltis semenrumicis
Cecidomyia semenrumicis

Hosts: Celtis laevigata, occidentalis

Gall.--On twigs, occasionally on petioles or stronger veins on either side of the leaf; upright, with 3–6 prominent, longitudinal, narrow, lateral wings and long, slender, curled apex; surface hairless, matte, green turning tan, or wholly or partly red; 6–8 mm long, 4–6 mm wide at mid-length; connection to twig or leaf a broad, persistent callus; when on leaf apparent on reverse as a widened vein; gall in cross section an elongate-ovoid larval chamber surrounded by thin wall beyond which the wings radiate.

Affinities.--Celticecis semenrumicis, C. ramicola, and C. ovata are distinguishable mainly from their galls. Galls of all three species are usually found attached to twigs. Those of C. semenrumicis ultimately develop distinct wings, are hairless, have a slender, curled apex, dehisce by early summer, and are known from the Mississippi Basin and Texas. Galls of C. ramicola have the same general distribution, are also hairless but never winged, have a short, straight apical extension, develop in late summer and early autumn and are slow to dehisce, in some cases persisting through late autumn. Galls of C. ovata are not sympatric with those of the other two, are instead more northern and eastern and hairy and wingless.

Biological note.--Galls first grow to their full length and only then develop wings. In Louisiana galls were found as early as late April on only partly expanded leaves, already with second instars. By June 6 only third instars were present, and galls dehisced readily although a few galls with viable full-grown larvae were found as late as August.

Distr.--KS, LA, MO, TX

Celticecis semenrumicis New Combination

Cecidomyiaceltis semenrumicis

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

31. Cecidomyidous galls on the tender twigs occurring either singly or in groups of two, three, four or more specimens; rarely, also, singly on the under side or even the upper side of the leaf. The gall bears a close resemblance to the winged seed-capsule (achenium) of a Rumex, but the wings vary in number from three to five and are often irregularly developed, while the tip always ends in a long curved spine. The wings terminate in a sharp ridge which is sometimes double. Gall opaque, not hairy, sculpture consisting of faint and irregular transverse striae; color pale yellowish-green, at apical third usually of a more decided green and darker. A longitudinal section reveals a single large, regularly ovoid cell surrounded by a thin hard wall. Average height of gall 4.5 mm, excluding the apical spine; generally as wide as high; length of apical spine variable, but usually a little more than half the height of the gall. This gall is easily recognized from its peculiar form.

Cecidomyia semenrumicis

Twig galls resembling seed capsules of Rumex, apically with a spine about one-half the length of the gall, the height, excluding the spine, 4.5 mm, the diameter approximately the same.

15. Cecidomyia sp. (PI. XVII, Figs. 15, 15a, 15b.) This gall exhibits a remarkable variation from the previously described simpler types. Riley, who first described it, gave a very complete description of it, which will be quoted. "31. Galls on the tender twigs, occurring either singly or in groups of two, three or four or more specimens; rarely also singly on the under side or even the upper side of the leaf. The gall bears a close resemblance to the winged seed capsule (achenium) of a Rumex, but the wings vary in number from three to five and are often irregularly developed, while the tip always ends in a curved, long spine. The wings terminate in a sharp ridge which is sometimes double. Gall opaque, not hairy. Color pale-yellowish green, at apical third usually of a more decided green and darker. A longitudinal section reveals a single large regularly ovoid cell surrounded by a thin hard wall. Average height of gall, 4.5 mm., excluding the apical spine; generally as wide as high; length of apical spine variable, but usually a little more than half the height of the gall." Riley.

The histology presents some points of special interest. The fibro-vascular bundles are found in the edge of the wings (PI. XVII, Fig. 15b), from which branches are distributed inwardly to the protective layer. This is better shown in the longitudinal section. Fig. 15a. The protective layer is found, as in most of the preceding galls, to be confined to the proximal two-thirds or three-fourths of the chamber wall. Trichomes line the apical canal to the point where it opens in the chamber.