The morphological diversity of spoon-winged lacewing larvae and the first possible fossils from 99 million-year- old Kachin amber, Myanmar

Antlion-like lacewings (Myrmeleontiformia) have comparably large predatory larvae; most well-known are the larvae of antlions (Myrmeleontidae) and owlflies (Ascalaphidae). Yet, larvae of spoon-winged lacewings (Nemopterinae, also an ingroup of Myrmeleontiformia) are less well studied and differ in their overall habitus, with a broader head and stouter mouthparts. We here review the known record of spoon-winged lacewing larvae and report two new fossil larvae preserved in 99 million-year-old Kachin amber from Myanmar that have some characteristics of spoon-winged lacewing larvae. We quantitatively compare morphological aspects of all these larvae with those from other myrmeleontiformian larvae. Our analyses suggest that one fossil larva may indeed be closely related to extant spoon-winged lacewings, but retains some plesiomorphies shared with Crocinae, the sister group of Nemopterinae. The other larva shows many unique features, but also some similarities to spoon-winged lacewing larvae, hence might be a highly specialised early representative of the lineage. These two larvae are the first potential larvae of Nemopterinae in the fossil record. Therefore, they are important indicators for the structure of the early diversification of lacewings. K e y w o r d s : ribbon-winged lacewings; Nemopterinae; Cretaceous; Burmite; quantitative morphology. Downloaded From: https://bioone.org/journals/Palaeodiversity on 21 Jul 2021 Terms of Use: https://bioone.org/terms-of-use 134 PALAEODIVERSITY 14, 2021 rinae are quite the opposite to those of Crocinae (i.e., long-necked antlions) as their body appears rather stout. In general, the larvae of Nemopterinae differ from those of other myrmeleontiformians by a rather broad head and shorter, stouter stylets. These larvae dig and live underground at a depth of between 150 and 300 mm under the surface (monserrat 1996; miller & stange 2012: 6). At least some larvae are blind (miller & stange 2012: 6), others have seven stemmata on each side of the head (monserrat 1996: 104). monserrat & martinez (1995: 62) mentioned that larvae of Nemopterinae feed on ants under laboratory conditions. It is possible that these larvae enter ant nests underground (yet also other mechanisms have been suggested). Other authors suggested a more general food spectrum (e.g., tröger 1993). For a long time, larvae of Nemopterinae were considerably less well known than those of Crocinae (macleod 1964). The situation has only slightly improved; even though there are more than twice as many described species of Nemopterinae than of Crocinae, many more larvae of Crocinae are still known, i.e., more than 70 (Haug et al. accepted a), while there are only less than 30 of Nemopterinae (see Results for details). We here review the reported records of larvae of Nemopterinae and compare their morphology quantitatively with that of other myrmeleontiformian larvae, especially long-necked antlions (larvae of Crocinae). Furthermore, we report two new larvae preserved in Myanmar amber that possess some characters shared with the larvae of Nemopterinae. 2. Material and methods