卵塊保護行動を行うヤマトコマチグモ Cheiracanthium lascivum の産卵数に影響を与える要因
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The breeding season and the factors affecting fertility of Japanese foliage spider, Cheiracanthium lascivum, were investigated in Kanazawa City of central Japan. In grasslands of three study sites, Asano, Tawara, and Katano, the nests made of leaves of perennial grasses were collected from late May to July. A total of 167 nests were collected, and 83 of them (49.7%) included a single adult female with an egg sac or spiderlings. The females attended their offsprings within the nests, but matriphagy, which is known in a congeneric species, C. japonicum, was not found. Average number of offsprings (eggs or spiderlings) per nest was 143.6ﾂｱ5.5 (SE). It was significantly different among the study sites, and the largest number was produced in Katano. The multiple regression analysis showed that the offspring number was positively correlated with the cephalothorax width of female spider in Asano and with the nest size in Katano. These results suggest that the offspring number in this spider is affected by the female size or the nest size, probably depending on environmental factors.石川県においてヤマトコマチグモの繁殖行動を観察し，その繁殖時期および産卵数の特徴について調べた．主に平野部の湿生草地3地点（浅野側河川敷，俵町水田地帯，片野鴨池湿地）で，葉を巻いて造られた本種の巣を定期的に採集した．167巣の巣が採集された．このうち親個体が卵塊または幼体と一緒にいた巣が49.7%あり，親個体が巣に閉じこもり，卵嚢あるいは幼体を保護すると考えられた．しかし，親個体が幼体によって食べられた痕跡のある巣は採集されなかった。1巣あたり平均143.6±SE 5.5個の卵あるいは幼体や脱皮殻が含まれていたが，産卵数は調査した3地点間で異なり，片野鴨池湿地で最も多かった．また重回帰分析の結果，浅野川河川敷では体サイズの大きな親ほど産卵数が多くなり，また片野鴨池湿地ではサイズが大きな巣ほど産卵数が多くなっていた．このようにヤマトコマチグモの産卵数は親個体のサイズと巣のサイズと関連していた．
- 2007-12-31