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| Aragomantispa lacerata
Pérez-de la Fuente & Peñalver, 2019.
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Abstract
Multiple predatory insect lineages have developed a raptorial lifestyle by which they strike and hold prey using modified forelegs armed with spine-like structures and other integumentary specialisations. However, how structures enabling the raptorial function evolved in insects remains largely hypothetical or inferred through phylogeny due to the rarity of meaningful fossils. This is particularly true for mantidflies (Neuroptera: Mantispidae), which have a scarce fossil record mostly based on rock compressions, namely isolated wings. Here, Aragomantispa lacerata gen. et sp. nov. is described from ca. 105-million-year-old San Just amber (Spain), representing the oldest and one of the few mantidflies hitherto described from amber. The fossil shows exquisitely preserved forefemoral spine-like structures composed of integumentary processes each bearing a modified seta, and prostrate setae on foretibiae and foretarsi. The fine morphology of these structures was unknown in fossil mantidflies. An assessment of integumentary specialisations from raptorial forelegs across mantispoid lacewings is provided. The present finding reveals how the specialised foreleg armature associated to the raptorial lifestyle in extant mantidflies was present yet not fully established by the Early Cretaceous, at least in some lineages, and provides palaeontological evidence supporting certain evolutionary patterns of acquisition of integumentary specialisations related to the raptorial function in the group.
Systematic palaeontology
Order Neuroptera Linnaeus, 1758
Family Mantispidae Leach, 1815
Subfamily Drepanicinae Enderlein, 1910
Genus Aragomantispa gen. nov
Type species: Aragomantispa lacerata sp. nov.
Diagnosis: Scape moderately elongate, about 4× longer than wide basally. Forecoxa not particularly elongate, shorter than forefemur (ratio forecoxae/forefemoral length 0.6). Forefemur not laterally flattened ventrally, widening distally and reaching its maximum width slightly beyond its midlength. Forefemur slightly longer than combined length of foretibia and foretarsus (about 1.1×). Forefemur with three types of spine-like structures composed of integumentary processes (IPs) each bearing a modified seta distally, arranged in two longitudinal rows: (1) two ectal and two ental major IPs bearing modified setae; ratio IP length/modified seta length of largest IP (basalmost, ental) 7:1, same ratio of three remaining IPs 3:1; (2) about ten ectal and five ental minor IPs bearing needle-like setae placed on proximal three quarters, ratio IP length/needle-like seta length about 1:3; (3) three ectal and three ental thick, minor IPs bearing thick setae on distal quarter, ratio IP length/thick seta length 3:2. Foretibia slightly arched ventrad, ventrally bearing a single row of closely-spaced prostrate setae, visible only on the distal half of the tibia. Foretarsus pentamerous, with tarsomeres cylindrical and compact. Foretarsomere 1 not particularly elongate, not produced apically. Foretarsomere 5 the longest. Foretarsomeres 1‒4 ventrally with one or two transverse pairs of prostrate setae each. Foretarsal prostrate setae distinct from those on foretibiae, i.e., thicker, with basal stretch erect at about 45° angle and a distal stretch abruptly inclined forwards and running parallel to the tarsus (not directed towards the cuticle). Claws paired and simple (not bifid or multipronged) in all legs. Arolium present in all legs. Meso- and metathoracic legs with tarsomeres 3 and 4 subequal in length. Hind wing with single trichosors along all anterior margin, with costal space very narrow; Sc meeting RA at about 2/3 of the wing length, pterostigmal area hyaline; two ra-rp crossveins before the pterostigmal area, 1rp-ma crossvein straight (not sigmoidal).
Etymology: After “Aragón”, name of the Autonomous Community in Spain where the San Just outcrop is located, and Mantispa, type genus of Mantispidae. Gender: feminine.
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| Photomicrographs of Aragomantispa lacerata gen. et sp. nov. (Mantispidae: Drepanicinae), holotype SJ-10-22, from San Just amber. Dorsolateral habitus, with discernible body parts tagged.
Abbreviations: Ar ‒ Abdominal remains, Fw ‒ Forewing, H ‒ head, Hw ‒ Hind wing, LFl ‒ Left foreleg, RFl ‒ Right foreleg. The asterisk marks a partially preserved snakefly wing (Raphidioptera).
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| Figure 1: Photomicrographs of Aragomantispa lacerata gen. et sp. nov. (Mantispidae: Drepanicinae), holotype SJ-10-22, from San Just amber. (b) Left foreleg in lateral (ectal) view, with inset showing pretarsal claws and arolium (arrow). |
Aragomantispa lacerata sp. nov.
Age and locality: San Just amber, northeastern Spain (Teruel Province). Dated as middle‒upper Albian, but most likely upper Albian according to new extensive, unpublished data on palynomorphs.
Etymology: Specific name is after Latin verb lacerare, meaning “to tear to pieces, to shatter, to destroy”, in its feminine, singular participle perfect passive conjugation, referring to the fragmentary and disintegrated appearance of the holotype’s body.
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| Figure 5: Reconstruction of Aragomantispa lacerata gen. et sp. nov. (Neuroptera: Mantispidae) striking a potential prey, an Alavesia sp. fly, on a hypothetical gleicheniacean fern. Antennal length, thoracic (including pronotal shape and the proportions of meso- and metathoracic legs) and abdominal morphology, striking pose and colouration of the new taxon based on extant mantidfly relatives. Species classified within the genus Alavesia have been found in two Spanish amber localities74, and the fern group is recorded as trichome inclusions and spores within the sediments associated to Spanish amber75; both were most likely abundant in the Iberian amber forest. |
Ricardo Pérez-de la Fuente and Enrique Peñalver. 2019. A Mantidfly in Cretaceous Spanish Amber provides insights into the Evolution of Integumentary Specialisations on the Raptorial Foreleg. Scientific Reports. 9: 13248. DOI: 10.1038/s41598-019-49398-1