Revision of the cyprinid genus Placocheilus Wu, 1977 in China, with description of a new species from Yunnan

Placocheilus is re-diagnosed on the basis of oromandibular structures compared to those of closely related groups. It is represented in China by three species restricted to Yunnan, namely P. caudofasciatus from the Tengtiaohe River (Nam Na), P. cryptonemus from the Nujiang Rive ( upper Salween River basin), and P. robustus, herein described as a new species from the Yuanjiang River ( Red River basin). P. robustus n. sp. is differentiated from its congeners in having a stout caudal peduncle ( depth 72.4-82.5% of its length) and the medium-sized scaleless midventral region of belly extended slightly beyond halfway from the pectoral- to pelvic-fin origin. It is further distinguished from P. caudofasciatus in having a coarsely crenulated rostral fold with 18-23 indentations on its distal margin and a smaller mental adhesive disc ( length 66.7-71.4% of its width and 37.0-43.1% of the head length).

昆虫假死性及建巢行为系列研究

本研究是围绕昆虫的假死行为及建巢相关行为两个方面进行的。首先通过对昆虫假死行为的研究历史和现状的综述，作者提出了假死行为是一种特殊拟态的观点。对长壮蝎蝽Laccotrephes robustus Stål成虫在不同的活动空间下(水体内外)的假死行为以及控制假死行为的关键部位的研究结果表明：(1)水体外假死时长明显高于水体中；(2)蝎蝽在水体内外假死行为的差别是对不同捕食压力的适应，能够提高自身的适合度；(3) 头部不是蝎蝽假死发生所必需的，控制胸部各对足完成假死动作的神经节可能是不同的。胡蜂类昆虫的建巢行为直接关系到其蜂群的发展和存活。平唇原胡蜂Prevespa barthelemy (Buysson)隶属于胡蜂科，是一种社会性昆虫。为研究已建造蜂巢的相关生物学特征，对其越冬后蜂巢进行了解剖观察。结果表明：(1)蜂巢中部较大的巢脾为主要的繁殖区；(2)幼虫和工蜂所占比率最高，占全巢各虫态总数的70%左右；(3)巢中成熟个体,除蜂后外其余全部为雌性工蜂；(4)由于当地气候适宜，越冬期的低温虽使其活动能力下降，但不会引起大量死亡，该胡蜂可以在原巢址内越冬。胡蜂类昆虫雌蜂单母建群的过程可以视为是昆虫社群生活起源的短暂重现，对单母建群行为的研究有助于理解昆虫群居生活的发生和发展。通过对焰马蜂Polistis adustus Birgham单母建群过程的观察，结果表明：(1)第一批工蜂羽化前，雌蜂同时担任蜂王和工蜂的职责；(2)各虫态发育历期卵为5-7 d；幼虫13-15 d；蛹为24-28 d；(3) 单母建群时期是决定未来蜂群发展的重要阶段，也是对马蜂类天敌昆虫进行保护和利用的关键时期。