Changes in the Morphological Diversity of Larvae of Lance Lacewings, Mantis Lacewings and Their Closer Relatives over 100 Million Years

Abstract

Neuroptera, the group of lacewings, comprises only about 6000 species in the modern fauna, but is generally assumed to have been more diverse and important in the past. A major factor of the modern-day ecological diversity of the group, and supposedly in the past as well, is represented by the highly specialised larval forms of lacewings. Quantitative analyses of the morphology of larvae revealed a loss of morphological diversity in several lineages. Here we explored the diversity of the larvae of mantis lacewings (Mantispidae), lance lacewings (Osmylidae), beaded lacewings (Berothidae and Rhachiberothidae, the latter potentially an ingroup of Berothidae), and pleasing lacewings (Dilaridae), as well as fossil larvae, preserved in amber, resembling these. We used shape analysis of the head capsule and stylets (pair of conjoined jaws) as a basis due to the high availability of this body region in extant and fossil specimens and the ecological importance of this region. The analysis revealed a rather constant morphological diversity in Berothidae. Mantispidae appears to have lost certain forms of larvae, but has seen a drastic increase of larval diversity after the Cretaceous; this is in contrast to a significant decrease in diversity in adult forms.

The Morphological Diversity of Antlion Larvae and Their Closest Relatives over 100 Million Years

“…As in many earlier analyses [ 78 , 79 , 81 , 82 , 83 ] (but not all, see [ 75 ]), the sub-sample size for the extant fauna is the largest. The sub-sample size of the Cretaceous larvae is the largest of the fossil faunas.…”

“…The impression of a more diverse lacewing fauna in the past is provided by numerous fossils, especially from the Mesozoic (e.g., [ 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]), but also from the Cenozoic era (e.g., [ 57 , 58 , 59 , 60 , 61 , 62 ]). These fossils include numerous different types of lacewing larvae (e.g., [ 26 , 47 , 50 , 52 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 ]), among them being also larvae that have been interpreted as representatives of the combined group including Myrmeleontidae and Ascalaphidae [ 47 , 50 , 52 , 57 , 62 , 86...…”

“…For other ingroups of Neuroptera, quantitative morphological comparison has identified losses of larval diversity over the last 100 million years [ 75 , 82 ], supporting a general loss of diversity within these groups. Yet, some of such studies have remained inconclusive as to whether there was a loss of diversity or a shift (for example into other habitats), which would have partly balanced a certain loss in one lineage by a diversification in another one [ 78 , 79 , 81 ]. In few instances, even a slight increase of morphological larval diversity could be observed [ 81 , 83 ].…”

“…Yet, some of such studies have remained inconclusive as to whether there was a loss of diversity or a shift (for example into other habitats), which would have partly balanced a certain loss in one lineage by a diversification in another one [ 78 , 79 , 81 ]. In few instances, even a slight increase of morphological larval diversity could be observed [ 81 , 83 ].…”

The first adult mantis lacewing from Baltic amber, with an evaluation of the post-Cretaceous loss of morphological diversity of raptorial appendages in Mantispidae

“…From the otherwise profusely rich Baltic amber only larval stages of mantis lacewings have been reported (Ohl 2011, Wunderlich 2012, and even these have been few in number (namely four larvae in two pieces of amber). This fact is noteworthy given that, although more than a dozen adults are known from Cretaceous ambers (Poinar and Buckley 2011, Pérez-de la Fuente and Peñalver 2019, Lu et al 2020, Shi et al 2020a, only a few larvae have yet been discovered (Haug et al 2018(Haug et al , 2021aPérez-de la Fuente and Peñalver 2019).…”