Investigation of the fossil mecopteran (scorpionfly) family Orthophlebiidae Handlirsch, Reference Handlirsch1906 started more than 170 years ago, when Mantell (Reference Mantell1844) described Panorpa liassica Mantell, Reference Mantell1844 from the Upper Triassic (Rhaetian) strata of Wainlode Cliff in the United Kingdom. The following year, Westwood (Reference Westwood and Brodie1845) described a new genus Orthophlebia, with one species O. communis Westwood, Reference Westwood and Brodie1845, which he included in the family Panorpidae. In 1906, Handlirsch established the new family Orthophlebiidae, to which he transferred Orthophlebia with O. communis as the type species. Almost ninety years later, Tillyard (Reference Tillyard1933) synonymised O. communis with O. liassica (= P. liassica). Since the first description of the genus Orthophlebia, more than 130 species have been described and assigned to the Orthophlebiidae (Giebel Reference Giebel1856; Brauer et al. Reference Brauer, Redtenbacher and Ganglbauer1889; Bode Reference Bode1905, Reference Bode1953; Handlirsch Reference Handlirsch1906–08, Reference Handlirsch1939; Martynov Reference Martynov1927, Reference Martynov1937; Tillyard Reference Tillyard1933; Martynova Reference Martynova1948, Reference Martynova1956; Riek Reference Riek1950, Reference Riek1955; Kolosnitsyna Reference Kolosnitsyna1964, Reference Kolosnitsyna1982; Willmann Reference Willmann1977, Reference Willmann1978, Reference Willmann1984; Lin Reference Lin1980, Reference Lin1986; Hong Reference Hong1983, Reference Hong1985, 2009; Sukatsheva Reference Sukatsheva and Rasnitsyn1985, Reference Sukacheva1990; Whalley Reference Whalley1985; Jell & Duncan Reference Jell and Duncan1986; Ueda Reference Ueda1991; Ren Reference Ren, Ren, Lu and Guo1995, Reference Ren1997; Zhang Reference Zhang1996; Hong & Xiao Reference Hong and Xiao1997; Novokshonov Reference Novokshonov1997a, Reference Novokshonovb, Reference Novokshonov1998; Willmann & Novokshonov Reference Willmann and Novokshonov1998a, Reference Willmann and Novokshonovb; Hong et al. Reference Hong, Chen and Liu2002; Novokshonov & Sukatsheva 2003; Hong & Zhang Reference Hong and Zhang2004, Reference Hong and Zhang2007; Grimaldi & Engel Reference Grimaldi and Engel2005; Hong & Guo Reference Hong and Guo2010; Petrulevičius & Ren Reference Petrulevičius and Ren2012; Qiao et al. Reference Qiao, Shih and Ren2012; Archibald et al. Reference Archibald, Mathewes and Greenwood2013; Krzemiński et al. Reference Krzemiński, Soszyńska-Maj, Bashkuev and Kopeć2015; Jarzembowski & Soszyńska-Maj Reference Jarzęmbowski and Soszyńska-Maj2017, this volume).
A lack of precise diagnosis of the Orthophlebiidae has resulted in the use of this family as a “wastebasket” for many taxa of ultimately unclear taxonomic position. Willmann (Reference Willmann1989) additionally considered Orthophlebiidae to be a paraphyletic group: “Orthophlebiidae”. Ongoing work on the taxonomic range and definition of Orthophlebiidae has resulted in the decision to remove some taxa from this family, including ‘Orthophlebia' martynovae Sukatcheva, Reference Sukatsheva and Rasnitsyn1985, now transferred to the family Austropanorpidae (Krzemiński et al. Reference Krzemiński, Soszyńska-Maj, Kopeć and Sukatsheva2017, this volume). Here we establish a new family, Worcestobiidae fam. nov., for two Late Triassic species originally included in Orthophlebiidae: Orthophlebia haradai Ueda, Reference Ueda1991 from Japan and O. gigantea Tillyard, Reference Tillyard1933 from England.
We present here a diagnosis of the newly established family and genus. The two species transferred to this new genus are redescribed and refigured. A well preserved forewing of the type species of the Orthophlebiidae is also refigured for comparative purposes (Fig. 1).
1. Material and methods
With the aim of revising the family Orthophlebiidae, most available holotypes, paratypes and lectotypes were examined. These comprise the material described by Handlirsch (Reference Handlirsch1906, Reference Handlirsch1939) in the University of Greifswald, Germany and the National History Museum, London (NHMUK); Tillyard's (Reference Tillyard1933) material in the NHMUK; and Bode's (Reference Bode1953) material in the University of Greifswald, Georg August University of Göttingen, Roemer- und Pelizaeus-Museum Hildesheim and Institut für Geologie und Paläontologie, TU Clausther-Zellerfeld in Germany. The types of Martynov (Reference Martynov1927, Reference Martynov1937), Martynova (Reference Martynova1948, Reference Martynova1956), Kolosnitsyna (Reference Kolosnitsyna1964, Reference Kolosnitsyna1982), Sukatsheva (Reference Sukatsheva and Rasnitsyn1985) and Willmann & Novokshonov (Reference Willmann and Novokshonov1998a, Reference Willmann and Novokshonovb) were examined in the Paleontological Institute, Russian Academy of Sciences in Moscow and the Jura Museum, Eichstätt in Germany. Additionally, new material was studied from the Middle-Upper Jurassic of Daohugou Village in the collection of the College of Life Sciences in Beijing, China and from the Lower Jurassic of England collected by one of the authors (RAC).
The holotype of Orthophlebia gigantea Tillyard, Reference Tillyard1933 and a wing of Orthophlebia liassica (Mantell, Reference Mantell1844), both housed in the Natural History Museum, London were restudied with the use of a stereomicroscope, under reflected light. Drawings were made from the photographs and digitally processed in Corel X5. The study of the holotype of Orthophlebia haradai (Ueda, Reference Ueda1991), housed in the Kitakyushu Museum of Natural History, Japan (KMNH), was based on good quality photographs accompanying the original description in Ueda (Reference Ueda1991).
The terminology of wing venation follows Willmann (Reference Willmann1989), with some modifications which are presented in Figure 1.
2. Systematic palaeontology
Order Mecoptera Packard, Reference Packard1886 Family Worcestobiidae fam. nov.
Type genus. Worcestobia gen. nov. Family monotypic with one genus.
Diagnosis. Distinguished from all other scorpionfly families by the combination of the following characters: vein Sc long, reaching the pterostigma without additional branches; costal field narrow; seven or eight veins reaching the outer margin in radial sector (Rs); R1 with one branch surrounding the pterostigmal area; Rs1 pectinate, forks into 3–4 simple veins reaching the outer margin; Rs2 forks into two single and straight veins Rs2a and Rs2b reaching the outer margin; Rs3 and Rs4 simple and straight; five longitudinal veins in medial sector in fore wing and four in hindwing; two cubital veins fused in basal part in fore wing, Mb fused with Cu1 in hindwing; three anal veins.
Remarks. The most important character, separating this new family from the Orthophlebiidae (and from all other families within the superfamily Panorpoidea), is the forking of Rs2 into two long veins Rs2a and Rs2b reaching the outer wing margin (see discussion).
Genus Worcestobia gen. nov.
Type species. Worcestobia gigantea (Tillyard, Reference Tillyard1933) = Orthophlebia gigantea Tillyard, Reference Tillyard1933.
Diagnosis. As for the family by monotypy.
Etymology. From Worcestershire, county in the West Midlands of England, where the type species was found.
Worcestobia gigantea (Tillyard, Reference Tillyard1933) comb. nov. (Fig. 2)
= Orthophlebia gigantea Tillyard, Reference Tillyard1933: 9, 42–43, fig. 15.
Material. Holotype NHMUK I. 11102, hindwing; Brodie collection from Strensham, Worcestershire; Lilstock Formation (Rhaetian).
Diagnosis. Rs1 forks into four veins reaching the outer margin; Rs1+2 almost equal in length to Rs; Rs2a almost equal in length to Rs2a+b.
Description. Only the hind wing is known, 17.5 mm length, 5.5 mm wide; vein Sc ends almost opposite R1 forking; vein R1 forks towards its end; radial sector (Rs) with eight veins reaching the outer margin; Rs almost equal in length to Rs1+2, Rs1+2 slightly shorter than Rs3+4; Rs1 pectinate, forking into four veins reaching the outer margin; Rs2 forks just beyond half its length into two veins Rs2a and Rs2b; Rs3+4 forks into two single veins, Rs3 three and a half times longer than Rs3+4; four veins in medial sector reaching the outer margin; M1+2 three times longer than M3+4; M1 almost two and a half times longer than M1+2, M3 seven times longer than M3+4; two cubital veins Cu and three anal veins.
Worcestobia haradai (Ueda, Reference Ueda1991) comb. nov. (Fig. 3)
= Orthophlebia haradai Ueda, Reference Ueda1991, p. 100, fig. 2.
Material. Holotype KMNH IP 000,002, forewing; Okuhata, Mine City, Japan; Upper Triassic (Carnian).
Diagnosis. Rs1 forks into three veins reaching the outer margin; Rs1+2 slightly shorter than Rs; Rs2a almost twice as long as Rs2a+b.
Description. Only the forewing is known, 14 mm length, 5 mm width; vein Sc ends beyond the forking of R1; radial sector (Rs) with seven veins reaching the outer margin; Rs1+2 slightly shorter than Rs; Rs1 forks into three single veins reaching the outer margin; Rs2 forks into two veins (Rs2a and Rs2b); Rs2a+b slightly longer than Rs2a; Rs1+2 almost equal in length to Rs and ca.¼ shorter than Rs3+4; Rs3 is three and a half times longer than Rs3+4; five veins in medial sector reaching the outer margin, M1+2 more than three times longer than M3+4; M1 slightly longer than M1+2, M3 seven times longer than M3+4, M4 very short and forks into two veins (M4a and M4b); two cubital veins and three anal veins.
3. Discussion
Through lack of precise diagnosis of the family Orthophlebiidae, some included species are evidently representatives of other families of Mecoptera. Two Late Triassic species, originally described as members of the Orthophlebiidae, are redescribed here and placed in the genus Worcestobia gen. nov.: Worcestobia gigantea (Tillyard, Reference Tillyard1933) comb. nov. from the Rhaetian of England; and Worcestobia haradai (Ueda, Reference Ueda1991) comb. nov. from the Carnian of Japan. These are now transferred to the newly established family Worcestobiidae fam. nov. A basic character and apomorphy of the new Triassic family, Worcestobiidae fam. nov., which distinguishes it from the Orthophlebiidae, is the forking of Rs2 into two long veins Rs2a and Rs2b, reaching the outer wing margin. Such forking of vein Rs2 does not occur in any other family included in the superfamily Panorpoidea, which includes Orthophlebiidae, since all other species within that family have vein Rs2 single and straight (Fig. 1). A similarly forked vein Rs2 occurs in some species of Permochoristidae, such as Sylvopanorpa carpenteri Martynov (Reference Martynov1940) and Kaltanidae; e.g., Pinnachorista sarbalensis Martynova (Reference Martynova1958). However, Worcestobiidae differs from Permian Kaltanidae in the former having no branches in the costal field, no cross-veins between Sc and R and fewer branches in the medial sector; and from Permochoristidae in the pectinate Rs1 and fewer veins in the medial sector, along with simple M1 and M2. The forking of Rs2 into long Rs2a and Rs2b is, therefore, quite rare among Mecoptera and clearly homoplastic in separate families that otherwise show substantial differences in venation. We consider that the presence of this distinctive character in two species previously regarded as Orthophlebiidae justifies their inclusion in the separate new panorpoid family Worcestobiidae.
The ongoing revision of the “Orthophlebiidae” group of species (see also Krzemiński et al. Reference Krzemiński, Soszyńska-Maj, Kopeć and Sukatsheva2017, this volume) will hopefully contribute to clarification of this important family. The phylogenetic and taxonomic system of this family has not been studied recently in the light of much new material and improved investigative techniques. A precise and updated diagnosis of Orthophlebiidae would be of great value to fossil Mecoptera specialists.
4. Acknowledgements
We are very grateful for the opportunity to work in, and for the hospitality extended to us by, the following institutions: University of Greifswald, Germany (Stefan Meller, Jorg Ansorge); Natural History Museum, London, UK (Claire Mellish); Georg August University of Göttingen, Germany (Alexandr Gehler); Roemer- und Pelizaeus-Museum Hildesheim (Jürgen Vespermann); Institut für Geologie und Paläontologie, TU Clausther-Zellerfeld, Germany (Carsten Brauckmann, Elke Groening); the Paleontological Institute, Russian Academy of Sciences, Moscow, Russia (Alexandr Rasnitsyn, Alexei Bashkuev); and the Paleontology and Geology Departments of Capital Normal University, Beijing, China (Dong Ren). The copyright of the photographs of Worcestobia gigantea and Orthophlebia liassica belongs to the Natural History Museum, London. The research was fully supported by the Polish National Science Centre (grant no. 2013/09/B/NZ8/03270).