Data from: Host-plant dissections reveal contrasting distributions of Crematogaster ants and their symbionts in two myrmecophytic Macaranga species

1. Ant–plant mutualisms are among the most widespread and ecologically important insect–plant interactions in the tropics. The multitrophic mutualism involving Macaranga plants (Euphorbiaceae) and Crematogaster ants (Formicidae) is the most diverse in Southeast Asia. This interaction also includes trophobiotic scale insects (Coccidae) and nematodes inhabiting ant refuse piles. 2. Here we compared two myrmecophytic systems, Macaranga trachyphylla with Crematogaster captiosa (Mt+Cc) and M. beccariana with C. decamera (Mb+Cd), using a fine-scale dissection of the stems. For the two plant species, for each internode we recorded both contents (ants, coccids, refuse piles) and structure (internode height, numbers of open and occluded ant holes). 3. There were significant patterns in the vertical distribution of ant colonies and their symbionts in the plant stems. Most coccids were kept in the highest sections of both systems, although Mb+Cd hosted a broader range of coccid species than Mt+Cc. Three nematode species were recorded, but with a rather low specificity to plant or ant species. Furthermore, the fine-scale distribution showed aggregation of closed holes with ant brood and separation of nematode-infested refuse piles from eggs. 4. Our study indicates that ants manipulate spatial colony structure via distribution of brood, holes and the symbionts. We suggest that ants optimise the location of refuse piles and occluded holes via spatial heterogeneity in their distribution among internodes. We discuss the protective role of occluded holes and demonstrate rather general interactions with other symbiotic fauna.

1. 蚁植互利共生（ant–plant mutualism）是热带地区分布极广、生态意义最为显著的昆虫-植物互作类型之一。其中，涉及大戟科（Euphorbiaceae）血桐属（Macaranga）植物与举腹蚁属（Crematogaster）蚂蚁（蚁科Formicidae）的多营养级互利共生体系，在东南亚地区物种多样性最为丰富。该互作体系还包含食养性蚧科（Coccidae）介壳虫以及栖息于蚁类垃圾堆中的线虫类。
2. 我们通过对茎秆进行精细解剖，对比了两组蚁栖植物体系：其一为粗柄血桐（Macaranga trachyphylla）与警觉举腹蚁（Crematogaster captiosa，记为Mt+Cc），其二为贝氏血桐（M. beccariana）与十齿举腹蚁（C. decamera，记为Mb+Cd）。针对这两种植物，我们对每个节间的内含物（蚂蚁、介壳虫、蚁类垃圾堆）与结构特征（节间高度、开放蚁孔与封闭蚁孔的数量）均进行了记录。
3. 蚁群及其共生体在植物茎秆内的垂直分布呈现出显著的规律性。两组体系中，绝大多数介壳虫均栖息于茎秆的最高区段，不过Mb+Cd体系所承载的介壳虫物种范围要比Mt+Cc体系更广。本研究共记录到3种线虫类群，但其对宿主植物或蚂蚁物种的特异性较低。此外，精细分布格局显示，封闭蚁孔与蚁卵幼体呈现聚集分布，且被线虫侵染的蚁类垃圾堆与蚁卵存在空间分离。
4. 本研究表明，蚂蚁可通过调控蚁卵幼体、蚁孔以及共生体的分布，来塑造蚁群的空间结构。我们推测，蚂蚁可通过节间分布的空间异质性，优化蚁类垃圾堆与封闭蚁孔的位置。本研究还讨论了封闭蚁孔的防御功能，并证实了该体系与其他共生动物类群间存在较为普遍的互作关系。