The lifestyle of symbiotic species in the genus Synalpheus can vary from pair living to eusocial. A pair-living social system commonly implies the adoption of a monogamous mating system. In this study, we used the symbiotic shrimp Synalpheus brevicarpus in association with the sponge Dysidea sp. to test the hypothesis that heterosexual pairs of symbiotic shrimps can adopt a monogamous mating system when living in association with a morphologically complex host. We collected a total of 40 sponges, which were inhabited by 76 shrimps: 41 males, 33 females, and 2 juveniles. Synalpheus brevicarpus is sexually dimorphic, with males displaying proportionately larger weaponry (snapping claws) and a smaller average body size than females. Sponges were more often inhabited by a pair of heterosexual shrimps than expected by chance. Larger sponges were inhabited by more than one pair of shrimps in which the sex ratio did not differ significantly from 1∶1. Pairs of heterosexual shrimps were recorded, with females carrying embryos in all stages of embryonic development. Our results indicate that S. brevicarpus is a pair-living shrimp with a monogamous social and mating system that may also guard spaces or areas within its sponge host. Our hypothesis of monogamy is supported by the observations on pair living, sex ratio, and sexual dimorphism in body size and weaponry in this species.

中文翻译：

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居住在海绵Dysidea sp。中的对虾对虾Synalpheus brevicarpus（Caridea，Alpheidae）的交配系统。（Demospongiae）

Synalpheus属中的共生物种的生活方式可能从成对生活到正常社会而变化。成对生活的社会系统通常意味着采用一夫一妻制的交配系统。在这项研究中，我们将共生虾Synalpheus brevicarpus与海绵Dysidea sp结合使用。为了检验以下假设：异性共生虾对与形态复杂的宿主生活在一起时可以采用一夫一妻制的交配系统。我们总共收集了40只海绵，其中有76只虾居住：雄性41只，雌性33只，幼鱼2只。短剑突是性二态，男性比女性显示出更大的武器装备（抓爪），平均体型更小。海绵经常被一对异性虾居住，而不是偶然的情况。一对以上的虾居住着较大的海绵，其性别比与1∶1没有显着差异。记录了成对的异性虾，雌性在胚胎发育的各个阶段都携带着胚胎。我们的研究结果表明，短链酵母是成对生活的虾，具有一夫一妻制的社交和交配系统，也可以保护其海绵宿主内的空间或区域。我们关于一夫一妻制的假设得到了关于该物种的成对生活，性别比以及身体大小和武器上的性二态性的观察结果的支持。