The long-tongued Cretaceous scorpionflyParapolycentropusGrimaldi and Rasnitsyn (Mecoptera: Pseudopolycentropodidae): New Data and Interpretations

Abstract

The genus Parapolycentropus, originally described for two species in 99 myo Burmese amber, is unique among Mecoptera for its long, thin proboscis and possession of just the mesothoracic pair of wings. a new series of 19 specimens with excellent preservation allows description and redescription of virtually all morphological details. Male terminalia are very similar to those of the holarctic Recent family of "snow fleas, " the Boreidae. Thoracic sclerites are highly convergent with nematocerous Diptera in the expansion of the mesothorax and great reduction of the proand metathoraces. The metathoracic wing vestige appears to be just the tegula; axial sclerites are lost. Details of the pretarsal claws are described; in P. paraburmiticus Grimaldi and Rasnitsyn the outer claw of the meso-and metathoracic pretarsi is elongate and the inner claw reduced. The proboscis is comprised not of a labial tube and "pseudolabellum" (contra Ren et al., 2009), but is mostly maxillary in origin, with the outer valves probably being galeae and the central, serrated stylet probably the hypopharynx. abdominal sternites are greatly reduced (more so in females), suggesting that the abdomen was distensible, a feature that is common in some fluid-feeding insects. The proboscis, claw, and sternite modifications indicate that Parapolycentropus fed on the hemolymph of small insects, not the blood of vertebrates.

Mouthpart homologies and life habits of Mesozoic long-proboscid scorpionflies

“…Our amber fossils reveal that the aneuretopsychid proboscis is not labial but maxillary in origin, consisting of one pair of galeae and one unpaired central hypopharynx, which is identical to that of Pseudopolycentropodidae sensu lato (5,12,17). The hypopharynx slightly tapers apically with the lateral sides curving upward and with a dorsally open food channel on the upper surface, which presumably passes directly into the large suction pump of the pharynx (Fig.…”

“…These long-proboscis scorpionflies most likely fed on liquid pollination drops of gymnospermous reproductive structures and perhaps engaged in pollination mutualisms with gymnosperms. Nonetheless, such floral visitation may not have been obligate, much like modern mosquitoes where females feed on blood and males feed on nectar (17). The flattened distitarsi and widely separated claws suggest grasping structures, and it is possible that Burmopsyche fed opportunistically on the hemolymph of other insects, at least in females, as similarly demonstrated for Parapolycentropus (17).…”

“…Nonetheless, such floral visitation may not have been obligate, much like modern mosquitoes where females feed on blood and males feed on nectar (17). The flattened distitarsi and widely separated claws suggest grasping structures, and it is possible that Burmopsyche fed opportunistically on the hemolymph of other insects, at least in females, as similarly demonstrated for Parapolycentropus (17). Thus, the ecological associations of mesopsychoids may be more complex and varied than simply obligate pollinators.…”

High niche diversity in Mesozoic pollinating lacewings

“…2b ). This structure is highly convergent with the galeae of the long-tongued Cretaceous scorpionfly, genus Parapolycentropus 31 , and it demonstrates that the galeae could temporarily come together and enclose the ligulae, thus forming a functional proboscis (e.g. Fig.…”

Direct evidence for eudicot pollen-feeding in a Cretaceous stinging wasp (Angiospermae; Hymenoptera, Aculeata) preserved in Burmese amber

“…Species of Mesozoic scorpionflies in and related to the family Pseudopolycentropodidae, have long proboscides, apparent perfect fits for probing the narrow pollen tubes of extinct gymnosperms 11 . The unusual, dipterous Parapolycentropus in Burmese amber, which has a fine, stylet-like proboscis, shares adaptive features with many empidid and ceratopogonid flies that today are insectivorous, a diet typical of mecopterans 12 , but a specimen of this scorpionfly was recently found with nearby Cycadopites pollen 13 . It may have actually fed on both: some hematophagous species of mosquitoes also feed on nectar and are effective pollinators 14 .…”