A field study has been made in the relatively narrow sympatric zone of Triturus cristatus and T. marmoratus, in the department Mayenne (France). Ecological data have been analysed. In the sympatric area specific preferences appear to exist: ecological isolation has developed in some areas. Typical T. marmoratus areas are hilly and wooded, provided with many terrestrial hiding-places, while forest pools and springs especially serve as spawning sites. T. cristatus areas are flat and open. Comparison with distribution data of 24 years ago shows expansion of T. cristatus at the expense of T. marmoratus, which presumably is true for the whole sympatric zone. The preferences of the species in combination with changes in environment by human intervention explain the detected changes in distribution. Ecological isolation as a phenomenon in the speciation of both species is discussed.

The Stigmella oxyacanthella species‐group sensu Johansson 1971, is revised here. Ten European species are recognized: torminalis (Wood), regiella (Herrich‐Schäffer), crataegella (Klimesch), hahniella (Wörz), magdalenae (Klimesch), nylandriella (Tengström), oxyacanthella (Stainton), pyri (Glitz), minusculella (Herrich‐Schäffer) and desperatella (Frey). Two species previously attributed to the group are here excluded: aceris (Frey) and aeneella (Heinemann). The latter is synonymized with Stigmella anomalella (Göze). Ten lectotypes are designated and an identification key to all the species is provided. Descriptions of adults and their genitalia and of larvae and their biology are given. The group has a holarctic distribution.

Aspects of fructification in Maianthemum bifolium were studied, mainly in natural populations in The Netherlands, but also in additional laboratory experiments. C. 15% of the plants were found to produce flowers. Onan average 25.1 ± 3.59 flowers and 2.7 ± 2.24 fruits were established per fruiting plant, anda mean of 1.2 fruits perflowering plant. It was ascertained that at soil pH '" 4 generally more fruits were produced than at higher pH values. At a coverage of ;;;, 35%, a highly positive correlation was found to exist between thecoverage percentage of undergrowth and the number offruits produced. Apresumed positive effect oftheundergrowth via a raised airhumidity on fruit production was affirmed by laboratory experiments. Syrphidae appeared to be the most important pollinating insects. However, insect pollination did not appear to bedecisive for fruit production.

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