Highly specialized Cretaceous beetle parasitoids (Ripiphoridae) identified with optimized visualization of microstructures. (26th October 2018)

• Record Type: Journal Article
• Authors: Batelka, Jan; Prokop, Jakub; Pohl, Hans; Bai, Ming; Zhang, Weiwei; Beutel, Rolf G.
• Is Part Of: Systematic entomology. Volume 44:Number 2(2019)
• Page Start: 396
• Page End: 407
• Publication Date: 2018-10-26
• Subjects: Insects -- Classification -- Periodicals; Entomology -- Periodicals; 595.7012
• DOI: 10.1111/syen.12331
• Languages: English
• ISSNs: 0307-6970

Abstract

Abstract: Extremely miniaturized longipedes insects (body length c . 0.3 mm) embedded in two pieces of Cretaceous amber from Myanmar are described and interpreted. Using inverted fluorescence and light microscopy for detailed analysis of microstructures, the inclusions were identified as primary larvae of the beetle family Ripiphoridae, subfamily Ripidiinae. While the structure of thoracic and abdominal segments including appendages corresponds well with the groundplan known in recent members of Ripidiinae, a curved prosternal ridge with prominent spines (each c . 5 μm), the reduced condition of stemmata and antennae and the lack of sharp mandibles are unique features within the entire family, apparently apomorphies of the longipedes larvae. A sinuate prosternal edge with a dense row of spines (prosternoctenidium) might be homologous with 'head ctenidia' in some previously described miniaturized conicocephalate larvae, but further investigation is needed. The morphological differences between the head of longipedes larvae and extant Ripidiinae are interpreted as adaptations to different groups of hosts and life strategies. Palaeoethology of the longipedes larvae is briefly discussed. In addition, the systematic placement of conicocephalate larvae from Canadian, Myanmar and Russian Cretaceous ambers, already interpreted by various authors as primary instars within Coleopterida (assigned to either Strepsiptera or to the coleopteran Tenebrionoidea: Ripiphoridae), is discussed. Abstract : Extremely miniaturized longipedes beetle larvae with body length reaching about 0.3 mm were discovered in mid‐Cretaceous amber from Myanmar. Using inverted fluorescence and light microscopy, we uncovered microstructural details measuring only a few micrometres, which are crucial for the assignment of primary larvae down to subfamily level. Larvae belong to the parasitoid family Ripiphoridae, subfamily Ripidinae, with reduced condition of stemmata and antennae and the presence of so‐called prosternoctenidium, characters unique within the family.