EARLY PERMIAN INSECT FOLIVORY ON A GIGANTOPTERID-DOMINATED RIPARIAN FLORA FROM NORTH-CENTRAL TEXAS

Quantitative analysis of 11,562 cm(2) of foliar surface area from an E arly Permian flora from north-central Texas reveals that 2.6% was remo ved by insect folivores. Of the 1346 foliar items analyzed, 31.8% were attacked by insect folivores. This Permian insect herbivory approxima ted one-third the level in modern tropical to temperate forests. Three taxa of Gigantopteridaceae exhibited disproportionately high insect c onsumption levels, ranging from 3.1 to 4.4% of leaf area, and attack f requencies of 39.6 to 82.8% - levels comparable to taxon-specific valu es for modem woody dicotyledonous angiosperms. Qualitative analysis of folivory type also indicates that five of the eight categories of her bivore damage occurring on this flora were confined to or overwhelming ly represented on Gigantopteridaceae, suggesting preferential host spe cificity for Gigantopteridaceae by insect folivores. By contrast, othe r pteridophylls, conifers, cycadophytes, and two taxa of uncertain aff inity, showed low levels of leaf area removal and attack frequencies. The Gigantopteridaceae, an enigmatic group of Permian plants with larg e, megaphyllous foliage, foreshadowed physiognomic attributes occurrin g in later angiosperms. Both groups had similar consumption patterns a nd intensities by insect folivores. Ln this moderately diverse Early P ermian flora, insect folivory was significant, at least in one riparia n environment outside the Euramerican coal-swamp ecosystem, indicating that modern modes and magnitudes of insect consumption of vascular pl ant tissue were in place during the Late Paleozoic. (C) 1998 Elsevier Science B.V. All rights reserved.