Diastrophus smilacis Ashmead, 1896

Feeds on: Reportedly induces galls on Smilax rotundifolia L. and S. herbacea L. but records remain unverified and suspect (M. L. Buffington, in litt.)

Distribution: United States: Florida, Illinois

Diastrophus smilacis

Described as irregularly rounded, abrupt pithy swellings on stem, one inch long by one-half inch in diameter. Polythalamous. Described from Chicago in 1896 and not collected since. Specimens much desired. It is suspected that there is an error here in the identification of the host plant. The adults are said to have emerged in Jan. and Feb. but the type flies in the National Museum bear the date label of May 1-8.

Diastrophus smilacis

Smilax rotundifolia, herbacea

"Irregularly rounded, abrupt smooth swelling on and usually surrounding stem. Pithy, polythalamous. About one inch long by one-half inch in diameter. Adults in Jan and Feb." Chicago IL is the type locality. The writer collected in the Chicago area for many years but was never able to find it. Host record questioned.

[Photo caption (no photo)]
On "Smilax sp." in the Chicago area. Reared in Jan and Feb. The writer collected for a dozen years in the Chicago area and was never able to find it. No other gall has yielded adults that agree with the types. Determination of the host questioned.

Diastrophus smilacis Ashmead

Gall. (Plate XXVIII, Fig. 6). On stems of smilax (Smilax rotundifolia, S. herbacea and S. havanensis). Polythalamous. Irregularly rounded, abrupt, swellings usually surrounding the stems, sometimes resembling the gall of Rhodites globuloides. Green when fresh and of a pithy structure. Diameter 16 imm.

Habitat: Illinois; Florida.

The type galls of this distinct species sometimes resemble those of the rose gall, Rhodites globuloidees Beut. Figure 6 on Plate XXVIII was made from a gall found on Smilax havanensis collected by Dr. E. Bessey at Miami, Florida. The types of D. smilacis are in the United States National Museum, and one female cotype in the American Museum of Natural History.

Aprostocetus smilax sp. nov.

It induces round galls on the stems of Smilax havanensis, often coalescing to form irregularly rounded, polythalamous swellings. Individual galls can also be found on the edge of leaves. Green when fresh and of a pithy structure (Figs 1, 63 inset), tissues around the emergence hole often form a black ring.

We conclude that A. smilax is the true gall inducer on Smilax L., and thus the host records of Diastrophus smilacis Ashmead and its inquiline Periclistus smilacis Ashmead, both from Smilax, are erroneous.