The specimen described herein comes from the Daohugou Lagerstätte, Ningcheng County, Inner Mongolia, China. The Daohugou fossil-bearing strata consist of mainly greyish white tuff, tuffaceous sandstone, tuffaceous siltstone and shale, and they are generally considered to be Middle Jurassic in age (Rasnitsyn and Zhang, 2004). The coleopteran assemblage is very diverse in the Daohugou fauna, and about 10 families have been described, and more fossils (especially Polyphaga) await description. The fossil insects are commonly preserved as carbonaceous compressions on the surface of grey tuffaceous siltstones, together with small freshwater conchostracans Euestheria sp. (Wang et al., 2009).

The specimen was examined dry and under alcohol, using a Nikon SMZ1000 stereomicroscope. Photographs were prepared using a digital camera (DXM1200) connected to the same stereomicroscope, and line drawings were readjusted on photographs using image-editing software (CorelDRAW X4, Adobe Photoshop CS and Helicon Focus). In the drawings, dotted lines indicate faintly seen parts and cleaved areas. Body length was measured along the midline from the mandibles to the elytral apices, and width was measured across the broadest part of the elytra. Pronotal length was measured along the midline; width was measured across the broadest part of the pronotum. In the present paper we refer to temples as the lateral regions of the head, starting from the posterior margins of the eyes and extending to the basal margin of the head. We tentatively followed the traditional terminologies summarized by Fedorenko (2009), and the venational terms by Kukalowá-Peck and Lawrence (1993) are given in parentheses. The studied material is stored in the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS).

Order Coleoptera Linnaeus, 1758.

Superfamily Byrrhoidea Latreille, 1804

Family Lasiosynidae Kirejtshuk et al., 2010.

Genus Lasiosyne Tan et al., 2007.

Lasiosyne laxa n. sp. (Fig. 1, Fig. 2 and Fig. 3).

The exact systematic position of Lasiosynidae remains open in the currently unstable elateriformian classification. In the original description (Kirejtshuk et al., 2010a), it was noted that lasiosynids possess characters encountered in several superfamilies of Elateriformia, which allows comparison with Dascilloidea, Buprestoidea, Elateroidea, or Byrrhoidea, without more precise attribution. In fact, most of the used characters, such as transverse coxae with exposed trochantins, retained sutures on meta- and, in some forms, also mesoventrites, and head of the prognathous type, appear to be just a complex of plesiomorphies (Lawrence et al., 2011) and could not be reliable evidence of the lasiosynid's close relationship with any of these superfamilies.

The wing of Lasiosyne fedorenkoi Kirejtshuk et al., 2010a and Kirejtshuk et al., 2010b is rather helpful and excludes the possibility of placing Lasiosynidae in Dascilloidea with a short radial cell (some undescribed species from the Upper Jurassic of Shar-Teg in Mongolia and Lower Cretaceous of Baissa in Transbaikalia have an rc whose length is five times greater than its width), normally developed MP3 + 4 (but without base), and CuP (MP3) with free base. Such wing venation resembles primitive buprestids in the subfamily Schizopodinae. However, according to Fedorenko's (2009) scheme of beetle wing evolution, this resemblance reflects derivation of the buprestoid venation pattern from a more primitive byrrhoid one and could be found in some byrrhoid families, such as Elmidae, Lutrochidae (Crowson, 1982), Callirhipidae (Forbes, 1926), and Ptilodactylidae (Crowson, 1978). This also supports Crowson's hypothesis of the close connection of Buprestoidea and Byrrhoidea (Crowson, 1982). L. fedorenkoi clearly differs from Schizopodinae in having a simple, not bilobed, fourth tarsomere, and from all Buprestoidea in having a much less developed interlocking mechanism which never extends to the mesoventral cavity and transverse coxae. Within Byrrhoidea, Lasiosynidae were compared with the four families of the psephenoid stem: Eulichadidae, Cneoglossidae, Ptylodactylidae and Callirhipidae (Kirejtshuk et al., 2010a). Unlike most byrrhoids, L. fedorenkoi has wings with an elongate rather than oblique radial cell and a short apical field, which brings Lasiosynidae closer to Callirhipidae and Eulichadidae. Callirhipidae are similar to lasiosynids in general appearance, but differ in a strongly declined head, narrowly separated antennal insertions, absence of the frontoclypeal suture and type of antennae–pectinate or flabellate.

Significant morphological similarity can be observed between Lasiosynidae and the small, primarily Asian family Eulichadidae (lasiosynid remains are mainly known from central and eastern Asia). The external appearance of Lasiosynidae, especially the type genus Lasiosyne, makes this family very similar to eulichadids, with large fusiform bodies, prognathous heads and big hemispherical eyes. Lasiosynidae, however, are strongly sclerotized, usually have only 11–12 deep elytral striae with punctures and mandibles without scoop-like apices. In addition, they have a number of primitive character states such as a distinct frontoclypeal suture, while in eulihadids it is replaced with just a transverse depression (Hájek, 2007 and Ivie, 2005). The discovery of L. laxa seems very important in understanding the place of lasiosynids within Byrrhoidea, because being a typical lasiosynid beetle, it possesses a few characters of the intermediate state. L. laxa is easily defined as a member of Lasiosynidae due to its big prognathous head with large, protruding mandibles and big eyes, fully divided procoxae, acute and protruded posterior pronotal angles, transverse coxae, elytra with shortened striae near the sutural margin, and meso- and metaventrites with longitudinal sutures. It definitely belongs to the genus Lasiosyne because of the coarse body sculpture, laterally protruding eyes, long temples, short proventrite, shortened second and third striae, and almost parallel-sided metaventrite. However, modern eulichadids and callirhipids have a transverse and trapeziform pronotum, and a katepisternal suture on the metaventrite, which is clearly visible on the metaventrite's basal third in the lasiosynid genera Anacapitis Yan (2009) and Parelateriformius Yan and Wang (2010), but is strongly shifted to the posterior margin in Lasiosyne Tan et al. (2007), and is completely absent in L. laxa. Moreover, all known Lasiosynidae are characterized by unfused abdominal ventrites, which distinguish lasiosynids from Eulichadidae with three connate basal ventrites. However, the discovery of a well-preserved abdomen in L. laxa n. sp. shows that the borders between these three ventrites are somewhat “thinner”, without intersegmental membranes (Fig. 1 and Fig. 3), which probably indicates their fusion. Before the discovery of Lasiosynidae, Crowson predicted that Eulichadidae, which he placed at the base of the trichotomy with Dryopoidea (which currently forms the Byrrhoidea) and the rest of the Elateriformia, should appear in the Lower Jurassic (Crowson, 1978 and Ivie, 2005). Nevertheless, it seems reasonable to retain Lasiosynidae as a separate family, at least until the rich collections from Daohugou have been studied in detail.

In their original description, the family Lasiosynidae included four genera: Lasiosyne, Anacapitis, Tarsomegamerus Zhang, 2005 and Bupredactyla. In the present paper, the genus Bupredactyla is excluded from this family, Kirejtshuk et al., 2010a and Kirejtshuk et al., 2010b showing normal pentamerous rather than “pseudotetramerous” tarsi, with small setal brushes on the ventral surface, and tarsomeres of subcylindrical but not of “moderately lobed” shape. The tarsomeres appear lobed because the tarsus is anteriorly orientated. Differences between Bupredactyla and Lasiosyne in habitus, shape of metepisterna and pronotum, occur only because Bupredactyla was preserved in lateral aspect, therefore it should be placed in Lasiosyne. The genus Tarsomegamerus shares some habitual similarities with Parelateriformius; however it differs from the rest of Lasiosynidae in having an elevated median portion of the prosternum as in some Elateridae and Byrrhidae; abdominal sternites with curved margins; very short first visible abdominal sternite; and third and fourth visible abdominal sternites separated by a wide membranous connection. In addition, Tarsomegamerus differs from Parelateriformius in having a long rc cell on the hind wings. Tarsomegamerus also lacks pseudotetramerous tarsi, five tarsomeres being seen in fig. 1e of Zhang, 2005 and also, but less clearly, in fig. 1d. Flattened portions of tarsomeres 2–4 overlapping each other make it difficult to define the shape of the tarsomeres, but this character could be seen in fig. 1f.

Here we propose the following four genera as belonging to the Lasiosynidae: Anacapitis, Lasiosyne, Parelateriformius, and Tarsomegamerus, with Anacapitis representing the least modified organization (Table 1), with all characters in the initial state, and Lasiosyne as the most derived; the genus Parelateriformius takes a somewhat intermediate position between them. The list of used characters is given below: •

eyes: (0) eyes do not protrude from the outline of the head; (1) eyes strongly protuberant;

All the above-mentioned genera were described on the basis of wholly preserved beetle material, but in many localities isolated elytra are most common without any bodies; thus here we place three additional genera within Lasiosynidae: Artematopodites, Dzeregia and Glaphyroptrodes Handlirsch, 1906. Initially, these genera had the status of “Polyphaga incertae sedis” and could not be associated with any beetle taxa because polyphagan elytra usually have “non-specific” systematic structures. With the recent finds of completely preserved beetles with the elytra of the same structure in the Chinese locality of Daohugou (Tan et al., 2007), it is possible to place these genera within Lasiosynidae.

Elytra of lasiosynid beetles are morphologically highly diverse, but rather easily divided into two morphotypes. Representatives of the genus Dzeregia have broad elytra without a median incision on the outer margin, deep, punctate striae and shortened stria 2. In Dzeregia small, strongly convex elytra probably belong to some forms of Byrrhidae, but bigger elytra look very similar to the elytra of Parelateriformius in Lasiosynidae. The majority of described isolated elytra, however, belong to the genus Artematopodites, which differs from Dzeregia in having a somewhat more elongated shape, two shortened striae and an incision on the outer elytral margin. The genus Glaphyropterodes differs from the previous two in having striae formed only by deep punctures.

Here, we therefore propose six genera for the family Lasiosynidae: Anacapitis (3 species), Lasiosyne (6 species), Parelateriformius (4 species), Artematopodites (9 species), Dzeregia (7 species) and Glaphyropterodes (2 species), with 31 species in total.