A well-preserved aneuretopsychid from the Jehol Biota of China (Insecta, Mecoptera, Aneuretopsychidae)

Abstract The Aneuretopsychidae is an unspeciose and enigmatic family of long-proboscid insects that presently consist of one known genus and three species from the Late Jurassic to Early Cretaceous of north-central Asia. In this paper, a new genus and species of fossil aneuretopsychid is described and illustrated, Jeholopsyche liaoningensis gen. et sp. n. Fossils representing this new taxon were collected from mid Early Cretaceous strata of the well known Jehol Biota in Liaoning Province, China. This finding documents the first formal record of fossil Aneuretopsychidae in China. In addition, this well-preserved and new material reveals previously unknown and detailed morphological structure of the mouthparts, antennae, head, thorax, legs and abdomen of this distinctive insect lineage.


Introduction
The Aneuretopsychidae is a depauperate and enigmatic, extinct family of mid Mesozoic Mecoptera erected by Rasnitsyn and Kozlov (1990). Currently, only one genus with three species has been described. Aneuretopsyche rostrata and A. minima were found in the Upper Jurassic Karabastau Formation of the South Kazakhstan (formerly Chimkent) Province in Kazakhstan, and A. vitimensis was recovered from the Lower Cretaceous Zaza Formation along the upper reaches of Vitim River, at the Baisa locality of western Transbaikalia in Russia (Rasnitsyn and Kozlov 1990). The establishment of the Aneuretopsychidae was very significant, as it was the first time that a mecopteroid insect was found to have exceptionally prolonged, siphonate mouthparts. The Aneuretopsychidae was initially and tentatively placed by Rasnitsyn and Kozlov (1990) into the Suborder Aneuretopsychina within the scorpionfly clade (Order Panorpida = Mecoptera). Moreover, the taxa was thought to have interesting feeding adaptations similar to cicadas and butterflies, particularly as it was difficult to interpret the first, enigmatic, proboscis observed in Mecoptera of any age.
The Aneuretopsychidae, together with mid Mesozoic Mesopsychidae (Ren et al. 2010a), and Pseudopolycentropodidae (Ren et al. 2010b), and now the Late Permian to Early Triassic Nedubroviidae (Bashkuev 2011), form a particularly interesting clade, the Aneuretopsychina, which lasted 150 million years from the Late Permian to the latest Early Cretaceous. This essentially preangiospermous lineage exhibited a tubular siphonate proboscis, indicating that mid Mesozoic scorpionflies were accessing pollination drops from gymnospermous plants, discussed elsewhere (Labandeira et al. 2007;Ren et al. 2009;Labandeira 2010). Such a mouthpart structure was convergent with and homologous to labial mouthpart elements of the brachycerous dipteran proboscis, but analogous to the maxillary glossae of lepidopterans which evolved during the Early Cretaceous (Labandeira et al. 2007;Labandeira 2010). Grimaldi et al. considered that these three families were not true mecopterans but rather stem-group mecopteroids showing remarkable parallel evolution with the Diptera (Grimaldi and Engel 2005;. By contrast, Ren and colleagues (Ren et al. 2009) indicated that this clade represents a major, early-derived lineage of basal Mecoptera.
Recently, we collected two fossils of Aneuretopsychidae, the first an excellently preserved part and counterpart, and a second poorly-preserved specimen lacking a counterpart, both from the well-known Yixian Formation. The Jehol Biota of the Yixian Formation has yielded abundant fossil insects associated with seed plants, some of which were potential pollen or nectar-feeders, such as members of the Orthoptera, Heteroptera, Coleoptera, Hymenoptera and Diptera (Ren 1998;Ren et al. 2010c). The new taxon reported here provides new morphological details for evaluating the phylogenetic position of this interesting family. Based on its unique venational characters, we erect a new genus with a new species, Jeholopsyche liaoningensis gen. et sp. n. The binomial name Jeholopsyche liaoningensis has appeared for the first time in Ren et al. (2009). However, diagnostic characters of this genus were mentioned only in the electronic Supporting Online Material, and were therefore not effectively published in terms of the International Code of Zoological Nomenclature (Article 9; ICZN 1999). We republish this genus and species herein by providing the required detailed description and other information to ensure no conflict with the Code and make the names nomenclatorially available from this paper.
The Early Cretaceous specimens were collected from the Yixian Formation at Huangbanjigou Village, in Shangyuan Township, near Beipiao City of Liaoning Province, China. There is general agreement that the age of the Yixian Formation is of late Barremian age, based on 40 Ar/ 39 Ar date of 125 Ma on sanidine and biotite minerals (Swisher et al. 2002), confirmed by 235 U/ 207 Pb dates on zircon crystals (Wang et al. 2001). This is the date that we accept herein. However, this date remains contentious, particularly for some Chinese scientists. Three potential ages historically have been proposed for the Yixian fossils; namely, the Late Jurassic (Ren et al. 1997;Zheng et al 2003), the transition from the Late Jurassic to the Early Cretaceous (Chen et al. 2004;Wang et al. 2004;Wang et al. 2005), and the Early Cretaceous (Swisher et al. 1999;Zhou et al. 2003).

Materials and methods
This study is based on two fossil specimens housed in the fossil insect collection of the Key Laboratory of Insect Evolution & Environmental Changes, College of Life Sciences, Capital Normal University, Beijing, China (CNUB; Dong Ren, Curator). The specimens were examined using a Leica MZ12.5 dissecting microscope, and illustrated with the aid of a drawing tube and formatted through Adobe Photoshop CS2 software.
The wing venation nomenclature used in this paper is based on the interpretations and system proposed by Novokshonov (Novokshonov 2002).
Included genera. In addition to the type genus, Jeholopsyche gen. n.
Diagnosis. In the forewing, Sc with three branches. R1 single. MP originates from stem of MP+CuA a little earlier (more basally) than Rs+MA from R. The Rs+MA bifurcation distinctly basad of the first bifurcation of MP. Both fore-and mid basitarsus shorter than remaining four segments in combined length. The basitarsus in hindlegs almost equal to remaining four segments in combined length.
Composition. Type species only.
Comparison. In the general venation scheme, the Jeholopsyche gen. n. differs from Aneuretopsyche Rasnitsyn & Kozlov, 1990 by the Sc in the forewing having three branches, R1 single, and Rs+MA bifurcation distinctly basad of the first forking of MP.
Description. Male: The specimen shows details of a nearly complete insect (Figs  1-5). A pair of forewings is almost symmetrically arranged, but hindwings are obscure.
Legs: Coxae smaller than those in typical scorpionflies. The legs entirely covered with annulate pubescence. Tarsi 5-segmented. The fore-and midlegs short, almost equal to antennae in length; their basitarsus distinctly shorter than remaining four segments combined in length. The hindlegs somewhat longer and slender, almost equal to forewing in length, with at least 1 apical spur; the basitarsus longest, almost equal to remaining four segments combined in length. All pretarsi with a pair of distinct claws, each developing a reduced and thickened pulvillus (Fig. 9).
Wings: Forewing slender (length/width ratio about 3.5:1); apical margin obscure, probably rounded; membrane delicate. A humeral vein present at the base of costal area. Sc long, reaching wing margin almost at same level as the MA bifurcation, with three inclined anterior branches; Sc area with some circular pale spots. Pterostigma probably absent. Both Rs and MA with two endings at or near the apical wing margin; Rs forking later than MA; MP forking later than where MA originates from Rs, with 4 long branches. Thyridium untraceable. Anal area broadened distinctly; A1 well developed. Forewing venational details is depicted in Fig. 6; hindwing untraceable.

Discussion and conclusion
Jeholopsyche liaoningensis is the first well-preserved member of the Aneuretopsychidae that exhibits exquisite details of the body, including head and all mouthpart elements, particularly the proboscis. Morphological details of the siphonate proboscis, including setae arranged into annulae, a fleshy pseudolabellum, and an ellipsoidal, subterminal mouth indicate that these insects were fluid feeders on the secretions and exudates from gymnospermous reproductive structures that also co-occur in Yixian deposits. From the proboscis structure and inferred ecological relationships, we conclude that J. liaoningensis was a pollinator of gymnosperm hosts that bore deep funnel or other tubular structures laden with nectar-like fluid rewards (Labandeira et al. 2007;Ren et al. 2009). During the mid Early Cretaceous, J. liaoningensis also was a member of a diverse guild of long-proboscid insects that included brachycerous files, kalligrammatid lacewings and perhaps early glossate moths (Labandeira 2010).