CNRS UMR 7625, Laboratoire Ecologie & Evolution, Université Pierre et Marie Curie, 7 quai Saint Bernard, Paris 75005, France.
Arthropod Struct Dev. 2013 May;42(3):257-64. doi: 10.1016/j.asd.2013.02.003. Epub 2013 Feb 28.
Among social Hymenoptera, only some ant genera have more than one morphological kind of non-reproductive adults. Individuals that are bigger than ordinary workers can function for defence and/or food storage. In Crematogaster (Orthocrema) smithi from Arizona, a third caste exists in addition to winged queens and workers; it is intermediate in size, weight and morphology, and individuals lay many unfertilized eggs that are mostly eaten by larvae (Heinze et al., 1995, 1999). We studied another three species belonging to the subgenus Orthocrema: Crematogaster pygmaea from Brazil, Crematogaster biroi and Crematogaster schimmeri from Taiwan. Using scanning electron microscopy and ovarian dissections, we show that 'intermediates' are a patchwork of queen-like and worker-like traits, just as in C. smithi; importantly the combinations differ across species. 'Intermediates' are numerically few in the colonies, and in C. pygmaea they are produced seasonally. Using histology we confirmed the lack of a spermatheca, thus they are not ergatoid queens. Based on the similarity of their mosaic phenotypes with those in other ant lineages, we suggest that Orthocrema 'intermediates' are a soldier caste with a specialized trophic function. This soldier caste has been reported in other Orthocrema species from Madagascar, Guinea and Costa Rica, suggesting that it is widespread in this subgenus.
在社会性膜翅目昆虫中，只有一些蚂蚁属具有不止一种形态的非生殖性成虫。比普通工蚁体型更大的个体可以起到防御和/或储存食物的作用。在来自亚利桑那州的 Crematogaster (Orthocrema) smithi 中，除了有翅的蚁后和工蚁外，还存在第三种品级；它的体型、体重和形态均处于中间状态，个体产下许多未受精的卵，这些卵大部分被幼虫吃掉（Heinze 等人，1995 年，1999 年）。我们研究了另外三个属于 Orthocrema 亚属的物种：来自巴西的 Crematogaster pygmaea、来自台湾的 Crematogaster biroi 和 Crematogaster schimmeri。通过扫描电子显微镜和卵巢解剖，我们发现“中间型”是蚁后和工蚁特征的拼凑，就像在 C. smithi 中一样；重要的是，这些组合在不同物种中存在差异。“中间型”在蚁群中数量较少，并且在 C. pygmaea 中它们是季节性产生的。通过组织学我们证实了它们缺乏受精囊，因此它们不是营孤雌生殖的蚁后。基于它们与其他蚂蚁谱系中类似的嵌合体表型，我们认为 Orthocrema“中间型”是一种具有特殊营养功能的兵蚁等级。这种兵蚁等级已在来自马达加斯加、几内亚和哥斯达黎加的其他 Orthocrema 物种中被报道，表明它在这个亚属中广泛存在。
