Toki Wataru, Matsuo Susumu, Pham Hong Thai, Meleng Paulus, Lee Chow-Yang
Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan.
, Koebaru 2-9-7, Nagasaki, 851-1132, Japan.
Naturwissenschaften. 2019 Aug 27;106(9-10):50. doi: 10.1007/s00114-019-1645-6.
The cavities of bamboos (Poaceae) are used by various animals. Most of the animals access these cavities either by existing cracks or by excavating bamboos with soft walls or small, thin-walled bamboos. Only a few animals excavate into the cavities of large and thick- and hard-walled internodes of mature bamboos. We studied two lizard beetle species (Coleoptera: Erotylidae: Languriinae), Doubledaya ruficollis and Oxylanguria acutipennis, that excavate into large internode cavities of recently dead mature bamboos and have morphological modifications. We observed that females of D. ruficollis used their mandibles to bore oviposition holes on Schizostachyum sp. (mean wall thickness = 3.00 mm) and O. acutipennis did so on Dendrocalamus sp. (3.37 mm) bamboos. Previous studies suggested that the markedly asymmetrical mandibles and needle-like ovipositors of females in the genus Doubledaya are adaptive traits for excavating hard-walled bamboos for oviposition. Therefore, we measured their mandibular lengths and ovipositor lengths. D. ruficollis females had greater asymmetry in the mandibles and shorter and less-sclerotized ovipositors than females of congeners using small bamboos. In contrast, O. acutipennis females had slightly asymmetrical mandibles and elongated, well-sclerotized ovipositors. Oviposition holes of D. ruficollis were cone-shaped (evenly tapering), whereas those of O. acutipennis were funnel-shaped (tube-like at the internal apex). This suggests that D. ruficollis females excavate oviposition holes using the mandibles only, and O. acutipennis females use both the mandibles and ovipositors. These differences suggest different oviposition-associated morphological specialization for using large bamboos: the extremely asymmetrical mandibles in D. ruficollis and elongated, needle-like ovipositors in O. acutipennis.
竹子（禾本科）的空洞被各种动物利用。大多数动物通过现有的裂缝进入这些空洞，或者通过挖掘壁软的竹子或小的薄壁竹子进入。只有少数动物会挖掘成熟竹子壁厚且坚硬的大节间空洞。我们研究了两种蜥蜴甲虫（鞘翅目：拟花萤科：朗花萤亚科），红颈双斑萤和尖翅尖花萤，它们会挖掘近期死亡的成熟竹子的大节间空洞，并且具有形态学上的适应性变化。我们观察到红颈双斑萤的雌性用它们的上颚在裂竹属竹子（平均壁厚 = 3.00毫米）上钻出产卵孔，而尖翅尖花萤的雌性在牡竹属竹子（3.37毫米）上这样做。先前的研究表明，双斑萤属雌性明显不对称的上颚和针状产卵器是挖掘硬壁竹子进行产卵的适应性特征。因此，我们测量了它们的上颚长度和产卵器长度。与使用小竹子的同属雌性相比，红颈双斑萤的雌性上颚不对称性更大，产卵器更短且硬化程度更低。相比之下，尖翅尖花萤的雌性上颚略有不对称，产卵器细长且硬化良好。红颈双斑萤的产卵孔呈锥形（均匀变细），而尖翅尖花萤的产卵孔呈漏斗形（内部顶端呈管状）。这表明红颈双斑萤的雌性仅用上颚挖掘产卵孔，而尖翅尖花萤的雌性用上颚和产卵器。这些差异表明在利用大竹子方面存在不同的与产卵相关的形态特化：红颈双斑萤的上颚极度不对称，尖翅尖花萤的产卵器细长呈针状。
