Ann. soc. entomol. Fr. (n.s.), 2010, 46 (1–2) : 193-197
ARTICLE
The earliest fossil schizopterid bug (Insecta: Heteroptera) in the Lower Cretaceous amber of Lebanon Dany Azar (1) & André Nel (2) (1)
Lebanese University, Faculty of Sciences II, Department of Biology, Fanar – Matn - P. O. box 26110217, Lebanon (2) UMR CNRS 7205, Muséum national d’Histoire naturelle, Entomologie, 45 rue Buffon, F-75005 Paris, France
Abstract. The schizopterid bug Libanohypselosoma popovi n. gen., n. sp. belonging to the subfamily Hypselosomatinae is described from the Lower Cretaceous amber of Lebanon. This fossil is the earliest record of the Schizopteridae. The species is distinguished from its related taxa, a discussion is given. Résumé. La plus ancienne punaise Schizopteridae (Insecta) dans l’ambre crétacé du Liban. Le schizoptéride Libanohypselosoma popovi n. gen., n. sp., appartenant à la sous-famille Hypselosomatinae, est décrit de l’ambre du Crétacé inférieur du Liban. Ce fossile est le plus ancien Schizopteridae connu. Ce nouveau genre est comparé aux taxons apparentés.
Keywords: Heteroptera; Schizopteridae; Hypselosomatinae; Lower Cretaceous; Lebanon.
S
chizopteridae – or jumping ground bugs – is the main family of the smallest heteropteran infraorder Dipsocoromorpha. These bugs have cryptic habits and a predominantly intertropical distribution. About 121 living species in 36 genera are known so far. Knowledge about the evolutionary history of the family, and even the group Dipsocoromorpha, is seriously hampered by the scarcity of fossils. Cenozoic schizopterids are recorded from Oligocene–Miocene Dominican and Mexican amber and from Eocene Baltic amber (Poinar 1992; Popov & Herczek 1993; Shcherbakov & Popov 2002, fig. 200; Engel 2004), when Mesozoic fossils are mentioned from Neocomian Lebanese amber (Grimaldi et al. 2002; Grimaldi & Engel 2005), but none of these fossils has been described so far. Perrichot et al. (2007) described the two Cretaceous genera Buzinia and Tanaia, respectively from the French and Myanmar amber. Here we describe the earliest schizopterid fossil, Libanohypselosoma popovi n. gen., n. sp., belonging to the subfamily Hypselosomatinae, after two fossil specimens preserved in the Lower Cretaceous amber of Lebanon. The terminology used in the systematic part follows that presented by Štys (1995), and Perrichot et al. (2007) for tegmina venation.
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[email protected] Accepté le 25 septembre 2009
Family Schizopteridae Reuter 1891
Subfamily Hypselosomatinae Esaki & Miyamoto 1959 Genus Libanohypselosoma n. gen. Type species. Libanohypselosoma popovi n. sp.
Etymology. In reference to Libano (= Lebanese in Latin) and Hypselosoma. Diagnosis. Closely similar to the extant genus Hypselosoma Reuter 1891 especially in the following characters: forewing with veins R, M1, M2, Cu, 1V, 2V present, defining three marginal cells and four narrow, elongate, median cells plus a pentagonal ‘trapezoidal cell’; tarsal formula 3/3/3. Distinguished from Hypselosoma by the presence of three macrosetae on the labrum, instead of five, and from all other Hypselosomatinae by its forewing venation.
Libanohypselosoma popovi n. sp. (Figs 1–5) Material Holotype specimen 1449 (male), paratype 845C (sex unknown, but probably a female), both in Azar collection, provisionally deposited in the Muséum National d’Histoire Naturelle, Paris, France. The material was prepared between two cover slips in Canada balsam medium as described by Azar et al. (2003). Etymology. The specific epithet is a dedication to our colleague and friend Prof. Yuri Popov. Type locality and horizon. Early Cretaceous, Hammana/ Mdeirij, Caza Baabda (Baabda District), Mouhafazit Jabal Libnen (Governorate Mount Lebanon), Central Lebanon. Diagnosis. As for the genus (vide supra).
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Description. All measurements are based on the holotype. Body length 1.147 mm (from head to wing apex). Head strongly declivous when viewed from the side, 0.358 mm wide; two long trichobotria, or ocular bristles, between eyes; no visible ocelli; antenna four-segmented, with several erect setae; first and second segments the shortest, length of segments 0.056/0.062/0.238/0.238 mm respectively; eyes large and broad, overlapping antero-lateral margin of pronotum; three macrosetae on labrum; labium three-segmented, length 0.159 mm; frons not delimited. Thorax. Pronotum transverse, without longitudinal ridges, length 0.113 mm, width 0.386 mm; scutellum short, length 0.170 mm, width 0.238 mm; proepisternal lobe broad, extending below eyes. Wings. Forewing hemelytrous (fig. 4), 0.909 mm long; clavus
large, with a pronounced depression; embolium broad; corium with veins R, M1, M2, Cu, 1V, and 2V defining three marginal cells and four narrow elongate median cells; R ending in M1; trapezoidal cell present, pentagonal. Hind wings present but hardly visible. Legs. Tarsal formula 3/3/3 in both specimens, with mesotarsi trimerous but incrassate (fig. 5). Fore coxae extending below eyes; long macrosetae on fore femora; fore tarsi without ventral spines; two elongate and setiform parempodia between tarsal claws. Leg measurements (in mm) as follows: fore femur, tibia, tarsi 0.272/ 0.198/0.090; mid femur and tibia, tarsi 0.284/ 0.215/0.102; hind femur, tibia, tarsi 0.284/ 0.352/0.113. Abdomen. Width 0.329 mm, setose.
Figures 1–2 Libanohypselosoma popovi n. gen., n. sp., holotype, specimen number 1449, female. 1, dorsal view photograph; 2, ventral view photograph.
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The earliest schizopterid bug
Discussion The general habitus of Libanohypselosoma popovi n. gen., n. sp is very similar to that of a Schizopteridae. According to the key of dipsocoromorphan families by Štys (1995), Libanohypselosoma popovi n. gen., n. sp fall in the Schizopteridae rather than in the Ceratocombidae because of the following characters: head strongly declivous; frons not delimited; antenna flagelliform with segments 1 and 2 thick and short, segments 3 and 4 strikingly longer and thinner, all
provided with many long, erect setae; proepisternal lobe broad, extending below eyes; pronotum without longitudinal ridges; fore coxae extending below eyes; foretarsi without ventral spines; costal fracture absent; macropterous. Furthermore, the hemelytra of Libanohypselosoma popovi n. gen., n. sp differ from those of the extant Ceratocombidae in the presence of narrow elongate cells, instead of 0–4 large cells (Štys 1982, 1983; Wygodzinsky 1953). Libanohypselosoma popovi n. gen., n. sp has the
Figure 3 Drawings of Libanohypselosoma popovi n. gen., n. sp., holotype, specimen number 1449, female, on left dorsal view, on right ventral view (scale bar = 1 mm).
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Figure 4 Drawing of the forewing of Libanohypselosoma popovi n. gen., n. sp. (scale bar = 0.3 mm).
characteristics of the subfamily Hypselosomatinae, viz. eyes very large, although smaller than usual in this subfamily (Štys pers. comm.), overlapping antero-lateral margin of pronotum; male mesotarsi trimerous but incrassate sensu Hill (2004) (= ‘four–segmented’ sensu Esaki & Miyamoto 1959; ‘pseudotetramerous’ sensu Emsley 1969), but the latter indicated that this last character can be found in at least the non-hypselomatine genus Silhouettanus Emsley 1969; large number of longitudinal veins of the hemelytra, i.e. all veins R, M1, M2, Cu, 1V and 2V are present and close a series of four inner elongate cells and three marginal cells (wing venation of Hypselosoma-type) (Esaki & Miyamoto 1959; Emsley 1969; Štys 1995). Hill (1980) gave a new diagnosis of the Hypselosomatinae based on the very large eyes and some other characters not visible in our fossils. He added that this definition is not very satisfactory, when compared with those for the Schizopterinae and Ogeriinae (not admitted by Štys 1995 and others). Affinities with this last subfamily can be excluded because of the three-segmented labium (Hill 1989, 1990, 2004) and the presence of four pairs of abdominal spiracles. The extant and fossil Hypselosomatinae currently comprises 13 genera (Emsley 1969; Štys 1970; Hill 1980; 1984; Carpintero & Dellapé 2006): the recent Hypselosoma, Glyptocombus Heideman 1906, Ommatides Uhler 1894, Pateena Hill 1980, Rectilamina Hill 1984, Cryptomannus Hill 1984, Macromannus Hill 1984, Ordirete Hill 1984, Lativena Hill 1984, Duonata Hill 1984, and Williamsocoris Carpintero & Dellapé 2006, plus the two Cretaceous genera Buzinia and Tanaia (Perrichot et al. 2007). All these genera but Hypselosoma are distinguished from Libanohypselosoma n. gen. by their venational pattern. Libanohypselosoma n. gen. differs from this genus in the presence of three macrosetae on the labrum, instead of five in Hypselosoma (see also Esaki & Miyamoto 1959; Hill 1984). Libanohypselosoma n. gen. shares this character with Buzinia and Tanaia. Libanohypselosoma n. gen. differs from Buzinia in the presence of a trapezoidal cell. Libanohypselosoma popovi n. gen., n. sp differs from Tanaia in the radial vein ending in M1, instead of ending in costal margin.
Conclusion
Figure 5 Photograph of the midtarsi of Libanohypselosoma popovi n. gen., n. sp.
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The present discovery of Early Cretaceous Hypselosomatinae which is strongly similar to an extant genus is highly significant as it provides evidence for the great antiquity of the bug family Schizopteridae. It is also consistent with the hypothesis that litterinhabiting insects were not severely affected by the end Cretaceous mass extinction event.
The earliest schizopterid bug
Acknowledgements. We sincerely thank Pr Pavel Štys and Dr Dominique Pluot-Sigwald for their helpful and kind review of the first version of the paper. This work is a contribution to the project ‘The Study of the Fossil Insects and their Outcrops in Lebanon: Geology of the Outcrops – Historical and Biodiversity Evolution’ accorded by the Lebanese University to DA.
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