A Harkány-Nagynyárádi-sík zárt lösztölgyesei (Pulmonario mollis-Quercetum roboris Kevey 2008)

The study deal with the phytosociological charac-teristics of oak forests growing on the loess-covered hills on the Harkány-Nagynyárád plain, where the author found rep-resentative stands of a recently described community, the closed pedunculate oak forest on loess (Pulmonario mollis-Quercetum roboris). This community occupies xero-mesic habitats between the more xeric habitat of the open steppe woodland (Aceri tatarici-Quercetum roboris) and the mesic habitats of the closed oak-hornbeam forest (Corydali cavae-Carpinetum). In terms of its ecological role, this community is the ecological equivalent of the closed pedunculate oak forest on calcareous sand (Convallario-Quercetum roboris). In the closed pedunculate oak forest, character species of dry grasslands (Festuco-Brometea, Festucetalia valesia-cae, Festucion rupicolae, etc.) play a subordinate role as opposed to the open steppe woodland, in which these spe-cies are prevalent. Unlike the open steppe woodland, the community harbors a number of mesic species (Querco-Fagetea, Fagetalia, Carpinenion) in the understorey, owing to the xero-mesic character of its habitat. It is separated from the often adjoining stands of closed oak-hornbeam forest, which grows at the bottom of the valleys, by the oc-currence of species characteristic of dry oak woods (Quer-cetea pubescentis-petraeae, Quercetalia cerridis, Aceri tatarici-Quercion), and the absence of several mesic spe-cies (Querco-Fagetea, Fagetalia, Carpinenion) typical in the oak-hornbeam forest. This community is thus classified as a member of the Polygonato latifolio-Quercenion roboris Kevey 2008 suballiance.

Composition of spider prey captured by the wasp Trypoxylon (Trypargilum) tridentatum tridentatum in two habitats in an oasis in Baja California Sur, Mexico

Trypoxylon (Trypargilum) tridentatum tridentatum Packard (Hymenoptera: Crabronidae) is a spider-hunting wasp in mesic and xeric habitats in the arid Baja California peninsula of Mexico. Spider (Araneae) prey were collected every 2 weeks from wasp trap nests. Individuals of the family Araneidae were the most abundant prey (60.9%), followed by Theridiidae and Mimetidae. Dictynidae, Anyphaenidae, Salticidae, Uloboridae, Tetragnathidae, Miturgidae, and Philodromidae were captured only in the mesic habitat. An unidentified species of Eriophora Simon (Araneidae) was the most frequently collected spider in the xeric habitat (29.0%), followed by Theridion submissum Gertsch and Davis (Theridiidae) (24.0%), which was the commonest prey species in the mesic habitat (21.1%), and Metepeira crassipes Chamberlin and Ivie (Araneidae) (16.5%). Nineteen species and three families are newly recorded as prey. The araneids Araneus lineatipes (O.P.-Cambridge) and Kaira alba (Hentz) and the uloborids Philoponella arizonica (Gertsch) and Uloborus segregatus Gertsch are new records for Baja California.

Unusual oak leaf galls from the middle Miocene of northwestern Nevada

Distinctive galls have been found on a fossil oak leaf from the Miocene Gillam Springs Flora of Washoe County, Nevada. The described galls are located on the leaf surface of Quercus hannibali Dorf, an analogue of the modern species Q. chrysolepis Liebmann. Similar galls are found on extant Quercus, but the fossils seem distinctive enough to warrant description as Antronoides schorni new genus and species. The occurrence of Antronoides schorni coincides with a rapid episode of change from a mesic to a more xeric habitat, with a concomitant shift from an oak-dominated to a conifer-dominated paleoflora. Recent work suggests that speciation and radiation of galling insects is highest in xeric environments, possibly due to decreases in rates of parasitism and disease. This pattern has been documented for modern galling insects and fits the qualitative fossil evidence we present. These galls also support the hypothesis that cynipids in the Antron group originated in Nevada or eastern California and migrated from their point of origin to their current range in the Sierra Nevada and Coast Ranges.

Basidiocarp development in Gloeophyllum (Lenzites) saepiarium in the natural environment

Basidiocarp development in Gloeophyllum saepiarium begins with the emergence of vegetative hyphae from the wood, their exposure to the relatively severe, fluctuating conditions of light and moisture, and their loss of direct contact with the substratum. In response to these changes the hyphae become organized into hyphal strands composed of generative hyphae and skeletal hyphae. Hyphal strands direct the growth of the advancing margin and are involved in the development of tomentum, context, and hymenophore. Their marked sensitivity to light and humidity accounts for the presence of growth zones in the basidiocarp. Atmospheric humidity is considered to be the factor of primary importance in influencing the growth, differentiation, and orientation of the hyphae in the perennial basidiocarp during the growing season. The close association of skeletal and generative hyphae allows the fruit body to withstand the extended dry periods characteristic of its xeric habitat, and to develop over a long period of time.