On the species of the genus Desmidium from Hokkaido,Japan

Summary Six species and two varieties of the genus Desmidium from Hokkaido have been investigated. Among them one species (D. grevillii), one variety (D. aptogonum var. acutius) and three facies (D. pseudostreptonema, facies ovalis; D. aptogonum, facies quadrangularis; D. baileyi, facies ovalis) are new to Japan. Zygotes were observed in three species and one variety (D. swartzii, D. aptogonum, D. baileyi and D. coarctatum var. cambricum) and parthenospores in one species (D. aptogonum).

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Zusammenfassung 6 Arten und 2 Variet?ten von der Gattung Desmidium aus Hokkaido werden hier beschrieben und illustriert. Es wurden 1 Art (D. grevillii), 1 Variet?t (D. aptogonum var. acutius) und 3 Facies (D. pseudostreptonema, facies ovalis; D. aptogonum, facies quadrangularis; D. baileyi, facies ovalis) von diesen als neu für die Flora Japans angesehen. In den 3 Arten und 1 Variet?t (D. swartzii, D. aptogonum, D. baileyi und D. coarctatum var. cambricum) wurde Zygoten betrachtet und in 1 Art (D. aptogonum) Parthenosporen.

     

Components of male fitness in relation to body size in Epirrita autumnata (Lepidoptera, Geometridae)

Abstract. 1. The effect of body size on different components of male fitness was studied for Epirrita autumnata , a geometrid known for its eruptive population dynamics. Body size is the main determinant of female fecundity in this species.
2. Longevity of males was found to have a weak negative correlation with body size at low temperatures. No significant correlation was found at higher temperatures.
3. We found no correlation between male size and female fecundity or egg size which is consistent with the small size of spermatophores in this species.
4. Small and large males were equally successful when allowed to compete for females in laboratory conditions.
5. In one or two field collections, males found mating were larger than males found singly. Large males also had an advantage in finding of virgin females, offered experimentally. No size-assortative mating was recorded.
6. We conclude that size-dependent mate location ability is the factor accounting for most of the variance in male fitness in E.autumnata. The dependence of fitness on body size may well be equally strong in males and females.     

Consequences of defoliation on phenological interaction between Epirrita autumnata and its host plant, Mountain Birch

1. Defoliation-induced changes in the budbreak phenology of Mountain Birches ( Betula pubescens ssp. tortuosa (Ledeb.) Nyman), and their effects on herbivore performance, were investigated during an outbreak of the spring-feeding geometrid, Epirrita autumnata (Bkh.).
2. Total defoliation (followed by refoliation) by E. autumnata larvae was required to achieve significant delaying of budbreak of Mountain Birch one year after damage.
3. Delayed budbreak has potentially deleterious effects on herbivore performance. However, E. autumnata larvae show phenotypic responses that increase the synchrony between larvae and leaves: high larval density, a prerequisite for severe defoliation, delays egg hatch in the following year.
4. Late hatching larvae performed as well on birches with delayed budbreak due to the previous year's total defoliation as did early hatching larvae on birches with earlier budbreak.