Higher resolution figure plates and original images of "Unexpected palaeodiversity of omaliine rove beetles in Eocene Baltic amber (Coleoptera: Staphylinidae: Omaliinae)"

Omaliine rove beetles in Eocene Baltic amber 35 Unexpected palaeodiversity of omaliine rove beetles in Eocene Baltic amber (Coleoptera, Staphylinidae, Omaliinae) Alexey V. Shavrin1, Shûhei Yamamoto2 1 Institute of Life Sciences and Technologies, Daugavpils University, Vienibas 13, Daugavpils, LV-5401, Latvia 2 Integrative Research Center, Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL 60605-2496, USA Corresponding author: Alexey V. Shavrin ([email protected]) Academic editor: Adam Brunke|Received 19 March 2019|Accepted 19 May 2019|Published 11 July 2019 http://zoobank.org/763EDE2B-5F0C-414D-8289-D37765E993E4 Citation: Shavrin AV, Yamamoto S (2019) Unexpected palaeodiversity of omaliine rove beetles in Eocene Baltic amber (Coleoptera, Staphylinidae, Omaliinae). ZooKeys 863: 35–83. https://doi.org/10.3897/zookeys.863.34662 Abstract Fossil records of the subfamily Omaliinae are fragmentary and most of them are less informative compression fossils. Baltic amber from the mid-Eocene of northern Europe is one of the most important sources of insect fossils, but only two reliably placed omaliines have been described. Here, we provide a general overview of this subfamily in Baltic amber. In total, five new extinct species of four genera in three tribes are described and illustrated: Geodromicus balticus sp. nov. (Anthophagini), Eusphalerum kantisp.nov. (Eusphalerini), Paraphloeostiba morosa sp. nov., Phyllodrepa daedali sp. nov., and Ph. icari sp. nov. (Omaliini). Additionally, we report on four species belonging to Eusphalerum, which remain unnamed, from the same amber deposit. The records of Eusphalerum include the first fossils of the tribe Eusphalerini, while that of Geodromicus may represent the second and the first definitive fossil record of the genus and tribe Anthophagini. Our discoveries highlight the unexpected palaeodiversity of Omaliinae in Baltic amber, further reinforcing the coexistence of thermophilous and temperate-loving beetles in Baltic amber and potentially indicating wetland and riparian habitats of amber-producing forests. Keywords Anthophagini, Eusphalerini, Omaliini, fossil, micro-CT ZooKeys 863: 35–83 (2019) doi: 10.3897/zookeys.863.34662 http://zookeys.pensoft.net Copyright Alexey V. Shavrin, Shûhei Yamamoto. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. RESEARCH ARTICLE Launched to accelerate biodiversity research A peer-reviewed open-access journal Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 36 Introduction With 1639 species in 117 extant and 14 extinct genera (Thayer 2016; A.F. Newton unpublished database 17 Jan. 2019), the rove beetle subfamily Omaliinae (Staphylinidae) is a relatively large group, currently composed of seven tribes: Anthophagini Thomson, 1859, Aphaenostemmini Peyerimhoff, 1914, Corneolabiini Steel, 1950, Coryphiini Jakobson, 1908, Eusphalerini Hatch, 1957, Hadrognathini Portevin, 1929 and Omaliini W.S. MacLeay, 1825. However, McKenna et al. (2015) recently demonstrated the nonmonophyly of Omaliinae with respect to three other subfamilies (i.e., Empelinae Newton & Thayer, 1992, Glypholomatinae Jeannel, 1962, and Microsilphinae Crowson, 1950) in the "Omaliine group of subfamilies based on two molecular markers. Their result supports the earlier results of Thayer (2000) based on larval morphology (although larvae of Empelinae are still unknown and therefore were not included in her study). These four subfamilies combined formed a monophyletic clade, sister to Proteininae (McKenna et al. 2015). Members of the Omaliinae are distributed worldwide, with the greatest diversity in the Holarctic and Oriental regions, predominantly in montane areas. A revision and clear diagnosis of Omaliinae still do not exist, and thus, the status of many supraspecific taxa is still unclear due to the difficulties of formally placing them within tribes (Newton and Thayer 1992, 1995). Omaliinae, or even the Omaliine group, have often been considered to be plesiomorphy-rich among Staphylinidae (Thayer 2016). However, this was not supported by the comprehensive molecular phylogenetic study by McKenna et al. (2015). The presence of paired ocelli in most taxa of Omaliinae has often been regarded as one of the most important characters to define the subfamily. Nevertheless, it is unclear whether ocelli should be interpreted as primitive or even apomorphic (Newton and Thayer 1995; Leschen and Beutel 2004; Cai et al. 2013; Thayer 2016). The extant omaliines are further characterized by having antennae inserted under the lateral margins of the frons, tarsal formula 5-5-5 (except Corneolabiini, 4-4-4; Steel 1950), procoxal cavities opened behind, well-developed prosternal and postprocoxal processes, procoxae conical and prominent, abdomen with six visible sternites, abdominal intersegmental membranes attached apically and with brick-wall-like pattern of sclerites, all spiracles well developed and functional, presence of wing-folding patches of microtrichia on some abdominal tergites, and anterior projection of abdominal sternite VIII with well-developed defensive glands (e.g. Klinger 1980; Dettner and Reissenweber 1991), as well as some features of genitalia and genital segments of both male and female (Thayer 1985; Newton et al. 2000; Peris et al. 2014; Zanetti et al. 2016). A brief history of fossil Omaliinae was recently provided by Chatzimanolis (2018). Fossil records of omaliines are relatively prevalent. Compared to the high diversity and abundance of extant Omaliinae, however, the records of extinct omaliines are still significantly fragmentary. Many of them are described with short descriptions, incomplete illustrations and problematic systematic placements (Chatzimanolis 2018). Hence, it prevents a comparison of these fossils to each other and to recent taxa. In addition, several extinct genera are known as “tribe incertae sedis” and not placed in any of the tribes mainly because of their poor preservation or difficulty in interpreting their mor- Omaliine rove beetles in Eocene Baltic amber 37 phology (Schaufuss 1890; Tikhomirova 1968; Ryvkin 1985, 1990; Herman 2001). Chatzimanolis (2018) listed five Jurassic omaliine genera (Tikhomirova 1968; Ryvkin 1985): †Archodromus Tikhomirova, †Globoides Tikhomirova, and †Porrhodromus Tikhomirova from the Upper Jurassic of Karatau, Kazakhstan; †Eophyllodrepa Ryvkin from the Middle-Upper Jurassic of Novospasskoe, Russia; and †Morsum Ryvkin from the Middle Jurassic of Kubekovo, Western Siberia. Two genera †Daiodromus Ryvkin and †Prodaia Ryvkin are known from the Upper Jurassic of Daya, Russian Transbaikalia, although Chatzimanolis et al. (2012) regarded them as Lower Cretaceous taxa. Later, Cai and Huang (2013) added the extinct genus †Sinanthobium Cai & Huang from the Middle Jurassic of Inner Mongolia, China. Compared to Jurassic compressions, only a handful of fossils are known from the Cretaceous, with only a single compression fossil, genus †Mesodeliphrum Ryvkin, described from the Lower Cretaceous of Turga, Transbaikalia (Ryvkin 1990). In addition, Peris et al. (2014) recently reported the first Mesozoic amber genus †Duocalcar Peris & Thayer (Omaliini) from opaque Lower Cretaceous French (Charentes) amber and visualized the beetle fossil by using phase-contrast Synchrotron Radiation x-ray microtomography (PPC-SR X-ray μCT). The Cenozoic omaliine fauna is also far from well understood. Scudder (1900) described the compression fossil species Geodromicus abditus Scudder (Anthophagini), from the Upper Eocene of Florissant, USA, although the preservation is not adequate to assess its systematic position. For example, the whole head was lost prior to description (Scudder 1900), which makes its generic identification highly doubtful or impossible. Nevertheless, according to the original description, the general body shape of G. abditus is similar to that of Geodromicus or some other related genera (for example Microedus), but there is no information about structure of the head and mouthparts. Another fossil species, Omalium antiquorum Wickham (Omaliini), with Proteinus-shaped body (Wickham 1913: pl. 5 fig. 3), is described from the same horizon (Wickham 1913), but again, the preservation of this fossil is insufficient to justify its taxonomic placement. Although the description is too short for final conclusions (Wickham 1913), this taxon may not belong to Omalium due to the proportions of the markedly transverse pronotum and wide elytra, which are consistent with many Proteinus (Proteininae) species. Other pre-Quaternary records include Anthophagus giebeli Heyden & Heyden (Anthophagini) from the Oligocene of Germany (Heyden and Heyden 1866), Omalium protogaeae Heer from the Miocene of Croatia (Heer 1847) and some unnamed fossils (e.g. Hopkins et al. 1971; Archibald and Mathewes 2000; Kiselev and Nazarov 2009). All these compression fossils need re-examination as generic assignments by the early paleontologists are doubtful. For example, A. giebeli can be assigned neither to Anthophagus nor Anthophagini. Based on the small body with two darkened spots in middle of the pronotum, it may belong to Eusphalerum or a small Omaliini (Phloeonomus-like) considering the shape of the very wide abdomen (Heyden and Heyden 1866). Schaufuss (1890) described Pseudolesteua insinuans Schaufuss from the mid-Eocene Baltic amber (ca 44 Ma) but this fossil may not even belong to Omaliinae (Zanetti et al. 2016). Unfortunately, Schaufuss’s material was likely to be lost or scattered during World War II (Vitali 2006); thus, it is probably Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 38 impossible to re-examine the type specimen. The only definitive omaliines in Baltic amber were recently described by Zanetti et al. (2016), representing two Omaliini species: Paraphloeostiba electrica Zanetti et al. and Phyllodrepa antiqua Zanetti et al. They were visualized with the PPC-SR X-ray μCT method, illuminating fine morphological details. Further, Hieke and Pietrzeniuk (1984) noted an “Anthobium” from Baltic amber identified by E. Reitter; however, this species has not been formally described (see also the history of confusion between Anthobium, Lathrimaeum and Eusphalerum in Tottenham (1939) and Shavrin and Smetana (2017)). The present paper provides an overview of the remarkable and unexplored palaeofauna of Omaliinae in Baltic amber. We report at least 18 fossil beetles in seven amber pieces, with the descriptions of five new extinct species in four extant genera from the tribes Anthophagini, Eusphalerini and Omaliini. The new species and unnamed specimens of Eusphalerum Kraatz represent the first definitive fossil of Eusphalerini, while that of Geodromicus Redtenbacher may represent the second and the first definitive fossil record of the genus and Anthophagini. These discoveries are significant for future phylogenetic and paleontological studies of the subfamily Omaliinae and related taxa. Materials and methods Eighteen adults in seven Baltic amber pieces were used in our study. Nearly all studied material is deposited in the Gantz Family Collections Center, Field Museum of Natural History (FMNH), Chicago, USA, with the assigned specimen numbers from FMNHINS-3260628 to FMNHINS-3260632 with addition of FMNHINS-3965993, but a single amber piece is derived from the private collection of V.I. Alekseev (Kaliningrad, Russia), under the registration number AWI-045. Each piece of amber is placed in a small transparent rectangular plastic envelope with the labels within. The age of Baltic amber is of great debate, with estimates from the Lower Eocene to Lower Oligocene (e.g. Perkovsky et al. 2007; Weitschat and Wichard 2010; Alekseev 2013; Bogri et al. 2018), although it is generally accepted as middle to upper Eocene. Here we tentatively follow the mid-Eocene (Lutetian: 44.1 ± 1.1 Ma) age based on the most recent estimations obtained by the absolute dating analyses of glauconites from Sambia Peninsula (Wappler 2005). The staphylinid fauna in Baltic amber is diverse and abundant, with the following 12 extant subfamilies recorded: Aleocharinae, Euaesthetinae, Omaliinae, Oxyporinae, Paederinae, Piestinae, Proteininae, Pselaphinae, Scydmaeninae, Staphylininae, Steninae, and Tachyporinae (e.g. Chatzimanolis and Engel 2011; Alekseev 2013; Cai et al. 2017; Yamamoto and Maruyama 2017). The amber pieces originate from the Baltic Sea Coast: Yantarny, Kaliningrad, Russia (FMNHINS-3965993, FMNHINS-3260629, FMNHINS-3260632, AWI-045); Wisła River, Gdańsk, Poland (FMNHINS-3260628); and the Baltic Sea Coast without further information (FMNHINS-3260630). The second author (SY) further prepared two specimens (FMNHINS-3260628 and FMNHINS-3260629) by polishing with emery papers of different grain sizes and a plastic buffing cloth. Omaliine rove beetles in Eocene Baltic amber 39 The following measurements are used in this paper and abbreviated as follows: HW maximum width of head including eyes; HL length of head (from base of labrum to neck constriction along head midline in dorsal view or from apical margin of mentum to neck constriction in ventral view (G. balticus sp. nov.)); OL ocular length (longitudinal); PLL×PLW (II, III) length×width of segments II and III of labial palpi; PML×PMW (III, IV) length×width of segments III and IV of maxillary palpi; AL length of antenna; PL length of pronotum; PW maximum width of pronotum; ESL sutural length of elytra (length of elytra from the apex of scutellum to the posterior margin of sutural angle); EW maximum width of elytra together; MTbL length of metatibia; MTrL length of metatarsus; AW maximum width of abdomen (at segment IV); TL total length (from anterior margin of clypeus to apex of abdomen). All measurements are given in millimeters and were made with a stereoscopic microscope equipped with an ocular micrometer. Some measurements of the body were difficult to do because of the specimen's partial visibility and orientation within the amber pieces; the resulting approximate values are marked with “~”, and the cases when measurements were not possible are marked with “?”. The description of the preservation of the material is given below the type material listing in a separate paragraph. The type labels are cited in inverted commas and separated from each other by a comma, different lines in labels of the types and historic labels are separated with ‘|’; explanations of the type labels are given in square brackets, necessary notes within the label are given in angle brackets. Specimens were examined using Nikon SMZ 745T and Nikon Eclipse E200 stereomicroscopes. A digital camera (Sony Alpha DSLR-A300) was used for photographs of habitus of Geodromicus balticus sp. nov. Other photographs were produced using a Canon 80D digital camera with a Canon MP-E 65 mm macro lens (F2.8, 1–5×), equipped with a Canon MT-24EX macro twin lite flash as light source. Then, image stacks were carried out using CombineZM software (Alan Hadley, Sheffield, UK). All figures were modified using Adobe Photoshop software. For one paratype (FMNHINS-3260630) of Eusphalerum kanti sp. nov., images were generated using x-ray micro-computed tomography (μ-CT), acquired with a micro-focus x-ray CT system (inspeXio SMX-100CT; Shimadzu) through the courtesy of Shimadzu Corp. (Kyoto, Japan). It was scanned at 60 kV under 60 μA, resulting in a voxel size of 5.0 μm. Specific settings of the scan are confidential and retained by the company. Rendering of the image volume was carried out using VGstudio max v. 2.2 (Volume Graphics, Heidelberg, Germany). Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 40 Systematic Palaeontology Order Coleoptera Linnaeus, 1758 Family Staphylinidae Latreille, 1802 Subfamily Omaliinae MacLeay, 1825 Systematic placement of fossils. The characters of the subfamily by which the fossil specimens describe here are unambiguously referred to Omaliinae are: shape of the body is variable but in general more or less wide, with short and less flexible abdomen than most staphylinids; elytra are variable in length and sometimes distinctly elongate and covering the entire abdomen (Newton and Thayer 1995); dorsal surface of the head, more or less close to hind margin, usually with ocelli (e.g. Hatch 1957; Moore and Legner 1979; Newton et al. 2000; Leschen and Beutel 2004; Thayer 2016), reduced in some taxa (see below); apical maxillary palpomere as wide as penultimate segment, but in Coryphiini and some taxa of Anthophagini and Omaliini it can be distinctly narrower; antennae attached under lateral margins of frons, filiform, moniliform or clavate; coxal cavities usually open; postcoxal process well developed (with some exceptions; see Newton et al. 2000); procoxae conical and prominent; epistomal suture absent, posterior face of metacoxa vertical (Newton and Thayer 1995; Thayer 2016); tarsal formula 5-5-5 (4-4-4 in Corneolabiini); abdomen with six visible sternites; abdominal tergites three to seven, usually with one pair of paratergites; intersegmental membranes attached apically and with brick-wall structures (e.g. Hammond 1971). Tribe Anthophagini Thomson, 1859 Genus Geodromicus Redtenbacher, 1857 Type species. Staphylinus plagiatus Fabricius, 1798 †Geodromicus balticus Shavrin & Yamamoto, sp. nov. http://zoobank.org/16755333-4CBD-4485-B51A-6B64459253B3 Figures 1, 2, 17–20 Type materials examined. Holotype: female, FMNHINS-3965993, complete specimen as inclusion in a piece of light yellow Baltic amber, 3.4 cm × 2.4 cm × 0.5 cm in size (Figs 1, 2), with glued small paper on plastic envelope labeled “6083”, with three colour photographs of habitus of the beetle (two of dorsal and one of ventral view) with rectangular stamp on the back of each labeled “Certificate 6083 [handwritten in blue] | Natural Baltic Amber with Inclusions | expert Jonas Damzen | International Amber Association | Names of Inclusions: | Staphylinidae [handwritten in blue] | Rove beetle [handwritten in blue]” <with additional round stamp on the left Omaliine rove beetles in Eocene Baltic amber 41 Figures 1–16. Amber specimens with inclusions of Omaliinae: 1, 2 Geodromicus balticus sp. nov. 3, 4 Eusphalerum kanti sp. nov. 5, 6 Paraphloeostiba morosa sp. nov. 7–9 Phyllodrepa daedali sp.nov. 10, 11 Ph.icari sp. nov. 12, 13 Eusphalerum sp. 2 (sp2), Eu. sp. 3 (sp3) and Eu. sp.4 (sp4) 14–16Eu.sp. 1 (specimens 1 to 9 (in the text: no. 1 to no. 9). Abbreviations: hl = holotype, pt = paratype, sn = syninclusion. Scale bars: 1.0cm (1–6, 10–16), 0.5 cm (7–9). side: “+SOCIETAS SVCCINORVM+INTERNATIONALIS”]>, with the following labels: “Baltic amber | Yantarny, Kaliningrad | Russia | (S. Yamamoto Coll.) | ?Geodromicus | Omaliinae, Anthophagini | Protobiae with minute | hairs | tarsi with long hairs” <rectangular label; handwritten on both sides of the label>, “HOLOTYPE | Geodromicus | balticus sp. nov. | Shavrin A. & Yamamoto S. des. 2019” <red rectangular label, printed> (FMNH). Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 42 Preservation. The specimen is poorly visible because it is partially covered with white cloud of microbubbles created by decay products interacting with resin, a characteristic of authentic Baltic amber (Cai and Huang 2013). This is especially noticeable on the anterior half of the body, under the apical and basal portions of the head, including the usual location of ocelli, and most of the pronotum. The abdominal tergites are not visible dorsally, as they are covered by the hind wings. The ventral side of the specimen is visible in detail except for the basal portion of the thoracic sclerites. Locality and horizon. Baltic amber from Yantarny, Kaliningrad, westernmost Russia; mid-Eocene (ca 44 Ma; Wappler 2005). Description. Measurements: HW (ventral): 0.76; HL (ventral): ~0.40; OL (ventral): 0.25; PLL×PLW (II, III): II: 0.05 × 0.03, III: 0.08 × 0.02; PML × PMW (III, IV): III: 0.10 × 0.06, IV: 0.16 × 0.05; PL (ventral): ~0.47; PW (ventral): ~0.87; ESL: 1.40; Figures 17, 18. Habitus photographs of Geodromicus balticus sp. nov. 17 Dorsal view 18 Ventral view. Scale bars: 1.0 mm. Omaliine rove beetles in Eocene Baltic amber 43 EW: 1.51; MTbL: 1.00; MTrL: 0.36 (I–IV: 0.20; V: 0.16); AW (IV): 1.41; TL: 3.80 (head of specimen slightly out of pronotum, thus the total length likely to be slightly shorter). Antennomeres with lengths × widths: 1: ? × 0.07; 2: 0.16 × 0.06; 3: 0.11 × 0.06; 4–5: 0.15 × 0.05; 6–7: 0.15 × 0.07; 8: 0.14 × 0.07; 9–10: 0.12 × 0.07; 11: 0.25 × 0.07. Body elongate; forebody convex. Specimen dark-brown and glossy, with antennomeres brown, mouthparts reddish-brown, legs yellow-brown with a somewhat darkened tibia. Habitus as in Figures 17–20. Head transverse, slightly elevated in middle, about twice as wide as long, with short temples, moderately strongly narrowing toward neck, with diagonal moderately deep grooves (visible only apical part of left groove), reaching level of apical third of eye; gular sutures slightly separated at narrowest point on level of basal third of length of eyes (Fig. 20). Eyes large and widely convex, with medium-sized facets. MedioFigures 19, 20. Habitus drawings of Geodromicus balticus sp. nov. 19 Dorsal view 20 ventral view. Abbreviations: a1–a11 = antennomeres 1–11; alp = apical labial palpomere; gc = gonocoxite; gr = groove; gs = gular suture; hw = hind wing; ip = intercoxal process; lb = labrum; lp = labial palpi; md = mandibles; mp = maxillar palpus; mt1, mt5 = metatarsomeres; nk = neck; s3–s8 = sternites 3–8; st = stylus. Scale bar: 1.0 mm. Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 50 Figures 24–29. Eusphalerum kanti sp. nov. (holotype: 24–26, 29 paratype: 27, 28) 24 habitus, dorsal view 25 habitus, ventral view 26 thoracic sclerites and legs, ventral view 27 apical part of elytra, abdomen and hind legs, posterodorsal view 28 head and antennae, dorsolateral view 29 head, antennae and forelegs, dorsal view. Abbreviations: a1–a11 = antennomeres; amp = apical maxillary palpomere; gc = gonocoxite; gs = gular suture; ip = intercoxal process; nk = neck; mtf = metafemur; mtt = metatibia; mtv = metaventrite; oc = ocellus; prt = protibia; pt1, pt5 = protarsomeres 1 and 5; s3–s8 = sternites III–VIII; sc = scutellum; st = stylus; t4–t8 = tergites IV–VIII. Scale bars: 1.0 mm (24, 25), 0.3 mm (26–29). Abdomen distinctly narrower than elytra (Figs 27, 40); apical margin of tergite VII with indistinct brick-wall sculpture; abdominal tergites with sparse small punctures and no visible microsculpture (Fig. 27); sternites VII and VIII of both males and females without modifications (Fig. 44). Male. Elytra as in Figure 24; apical margin of elytra widely rounded (Figs 30, 31). Apical margin of abdominal tergite VIII somewhat straight. Apical margin of abdominal sternite VIII widely rounded (Fig. 27). Omaliine rove beetles in Eocene Baltic amber 51 Figures 30–33. Eusphalerum kanti sp. nov. (holotype, male: 30, 31 paratype, female: 32, 33): 30, 32 elytra (schematic drawings) 31, 33 apical part of elytra. Scale bars: 0.3 mm. Female. Elytra as in Figure 21; apical margin of elytra distinctly prolonged at sutural apex (Figs 32, 33). Apical margin of abdominal tergite VIII and sternite VIII (Figs 27, 40) straight. Genital segment with markedly elongate gonocoxites and very small styli (Figs 27, 40). Etymology. Patronymic, the species is named in honour of the great German philosopher Immanuel Kant (1724–1804), the author of the doctrine of transcendental idealism. Remarks. The paratype of Eu. kanti sp. nov. was visualised three-dimensionally using a micro-CT scan. Although the result was not very satisfactory, we could observe the fossil from multiple additional angles (Figs 34, 44). Based on this scan, we could describe more characters that were not visible with light microscopy. The fossil was assigned to the tribe Eusphalerini and genus Eusphalerum based on the general shape of the body, shapes and length of short and slightly widened tarsomeres 1–4, with dense and elongate ventral setae, together about as long as apical tarsomere, and shape of the elytra of female slightly longer than that of male, with prolonged portion at sutural apex (Figs 32, 33). This floricolous genus contains 260 valid species (Zanetti 2014) Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 52 Figures 34–44. Eusphalerum kanti sp. nov., paratype, reconstructions from x-ray micro-computed tomography (μ-CT) 34 habitus, dorsal view 35 habitus, ventral view 36 habitus, lateral view 37 forebody, dorsal view 38 head and prothorax, ventral view 39 head and pronotum, anterodorsal view 40 elytra and abdomen, posterodorsal view 41 pterothoracic sclerites, ventral view 42 head, lateral view 43 neck and anterior portion of pronotum, dorsal view 44 abdomen, lateroventral view. Copyright 2015 Shimadzu Corporation. Omaliine rove beetles in Eocene Baltic amber 53 distributed in the Holarctic Region. Earlier, the genus was subdivided into two subgenera: Eusphalerum and Pareusphalerum Coiffait, 1959 (Zanetti 1987), but because several species of sensu stricto and Pareusphalerum were overlapping in some morphological characters, the latter was synonymized with the nominotypical taxon (Tronquet and Zanetti 2008). Based on general morphological features of the aedeagus, female accessory sclerite and, in some cases, shapes of the modified apical abdominal sternites, several species groups have been erected for many species of the genus (e.g. Zanetti 1987, 1993, 2014). However, to date, this diverse genus remains insufficiently studied globally and is in need of further phylogenetic revision because of unclear relations between both species groups and the tribe Eusphalerini with related Omaliini. The new species is difficult to compare with extant species as they typically differ from each other by the morphology of the aedeagus and female genital structures. However, based on the shape of the strongly elongate and dimorphic elytra, Eu. kanti sp. nov. is like members of the following species groups: North American convexum (Zanetti 2014; four species distributed in Canada and USA) and western Palaearctic amplipenne (Zanetti 1993; one species known from Turkey), longipenne (Zanetti 1987; six species distributed in Middle and South Europe), montivagum (Zanetti 1987, 1992, 1993, 2004, 2012a; 10 species distributed in Central and Southern Europe and Turkey) and anale (Tronquet and Zanetti 2001; three species from the central-western part of Europe). The new species differs from the convexum group by the presence of the postocular carina, by the dorsal portion of head without visible impressions, by the shape of the apical tarsomere slightly longer than that in species of convexum group and by the abdominal sternite VII of male without modifications. It differs from the amplipenne group by its somewhat smaller and darker body, sparser punctation of the forebody and shape of metatarsus of male, slightly curved in Eu. amplipenne (see Zanetti 1993: fig. 13). The new species shares similar length of the body and postocular carina with some species of the longipenne group, but differs by the darker body and longer apical tarsomeres. Based on the dark body, general characters of punctation and microsculpture of head and pronotum, Eu. kanti sp. nov. is somewhat like some species of the montivagum and anale groups, for example Southern European Eu. schatzmayri (Koch, 1938), Eu. anale (Erichson, 1840), Eu. brandmayri (Zanetti, 1981), and Eu. coiffaiti Nicolas, 1974, but it differs by the larger body (body length of members of the montivagum and anale groups varies from 1.50 to 2.50 mm) and more transverse pronotum. From all these groups, Eu. kanti sp. nov. differs by the absence of distinct grooves in front of the ocelli and elongate antennomeres 2–4 (Fig. 28). Tribe Omaliini MacLeay, 1825 Genus Paraphloeostiba Steel, 1960 Type species. Paraphloeostiba marianicola Steel, 1960. Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 54 †Paraphloeostiba morosa Shavrin & Yamamoto, sp. nov. http://zoobank.org/722E3364-B487-4F94-8BA6-5A38BD4A1C00 Figures 5, 6, 45–53 Type materials examined. Holotype (female), FMNHINS-3260632, complete specimen as inclusion in a piece of small yellow Baltic amber, 15.6 mm × 13.1 mm × 4.0 mm in size (Figs 5, 6), with the following labels: “14[printed] 11[handwritten]- SYAC 00 [printed]06 [handwritten] | Baltic / Burmite | Other: | Larva / Adult | Omaliinae [handwritten] | Kalini[n]grad [handwritten] | Shûhei Yamamoto’s | Amber Collection” <large rectangular label, printed>, “Kaliningrad, RUSSIA | Shûhei Yamamoto’s | Amber Collection | (SYAC0006)” <small rectangular label, printed>, “[FMNH barcode at left side of label] FMNHINS | 3260632 | AMBER [handwritten] | FIELD MUSEUM | Wet” <small rectangular label, printed>, “HOLOTYPE | Paraphloeostiba | morosa sp. nov. | Shavrin A. & Yamamoto S. des. 2019” <red rectangular label, printed> (FMNH). Preservation. The specimen is located at an angle with the head somewhat deeper in the amber piece (Figs 5, 6); the specimen is clearly visible from both dorsal and ventral sides. Syninclusions: round and elongate air bubbles near the specimen on from the ventral side of its body, and elongate piece of plant material located close to the dorsal surface of amber piece near the beetle. Locality and horizon. Baltic amber from Yantarny, Kaliningrad, westernmost Russia; mid-Eocene (ca 44 Ma; Wappler 2005). Description. Measurements: HW: 0.36; HL: 0.29; OL: 0.17; AL: 0.51; PML × PMW (III, IV): III: 0.03 × 0.03, IV: 0.06 × 0.02; PL: 0.31; PW: 0.74; ESL: 0.52; EW: 0.77; MTbL: 0.38; MTrL: 0.15 (I–IV: 0.07; V: 0.08); AW: 0.75; TL: ~1.80. Antennomeres with lengths × widths: 1: 0.07 × 0.03; 2: 0.05 × 0.02; 3: 0.05 × 0.01; 4: 0.03 × 0.02; 5: 0.04 × 0.02; 6–7: 0.03 × 0.03; 8: 0.03 × 0.04; 9–10: 0.04 × 0.05; 11: 0.10 × 0.05. Body moderately wide, glossy (Fig. 45), black, with mouthparts, femora, and apical parts of abdominal tergites reddish-brown, and tarsi yellow-brown. Body laterally as in Figures 47 and 48. Body without visible microsculpture and setation except of paratergites and abdominal tergite VIII with long erect setae (Fig. 48). Head 1.2 times as wide as long, with slightly convex posterior portion, dense and small punctation and postocular carina (Fig. 49). Head laterally as in Figure 49, anteroventrally as in Figure 50, and ventrally as in Figure 51. Eyes large, with medium-sized facets, broadly convex, with distinct infraorbital carina (Figs 49–51). Ocelli moderately large, situated at level of posterior third of eyes, distance between ocelli about twice as long as distance between ocellus and medial margin of eye (Fig. 45). Labrum with widely rounded apical margin (Figs 46, 51). Apical maxillary palpomere distinctly longer and slightly narrower than penultimate, swollen in middle and elongate, from middle gradually narrowing toward rounded apex (Figs 49–51). Submentum large, trapezoidal; apical labial palpomere elongate, from middle narrowing apicad (Fig. 49). Gular sutures with markedly rounded posterior parts widely separated from each other below level of posterior margins of eyes (Figs 50, 51). Gena with rugose isodiametric microsculpture (Figs 50, 51). Antenna moderately short, exceeding basal portion of pronotum, with Omaliine rove beetles in Eocene Baltic amber 55 Figures 45, 46. Habitus of Paraphloeostiba morosa sp. nov. 45 dorsal view 46 ventral view. Scale bars: 1.0 mm. sparse elongate setation; basal antennomere swollen, more than twice as long as wide, antennomere 2 elongate, slightly widened apicad, 3 thin, as long as 2, 4, and 5 markedly widened apicad, 6 and 7 as long as wide, 8–10 slightly transverse, apical antennomere wide, from apical third slightly narrowing toward rounded apex (Figs 45–49). Pronotum with slightly convex surface, markedly transverse, more than twice longer than broad, twice wider than head, from middle slightly more narrowed anterad than posterad, with widely rounded anterior and scarcely rounded posterior angles; apical margin widely rounded, distinctly shorter than somewhat concave posterior margin; paramedian longitudinal impressions indistinct, wide and long, occupying most of middle portion; lateral margins narrowly emarginate, with indistinctly concave laterobasal margins; posterior angles without depressions (Fig. 45). Dorsal surface of pronotum with more or less regular small and dense punctation, distinctly denser than in posterior portion of head Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 56 Figures 47, 48. Habitus of Paraphloeostiba morosa sp. nov., lateral view. Abbreviation: oc = ocellus. Scale bars: 1.0 mm. (Fig. 45). Prosternum with widely open procoxal fissures, exposing trochantins, and very long intercoxal process, with acute apex reaching apical part of procoxae (Figs 46, 51). Median part of mesoventrite somewhat convex, with very long acute intercoxal process, reaching more than halfway along the length of the mesocoxae and moderately wide apex of metaventral process (Fig. 46). Scutellum large and triangular, with rounded apex and dense punctation in apical part (Fig. 45). Metaventrite with moderately wide metacoxal cavities (Fig. 46). Median part of prosternum and metaventrite with indistinct and sparse small punctures; mesanepisternum with diagonal microsculpture; median portions of prosternum and metaventrite, including intercoxal processes, with transverse meshes (Fig. 46). Elytra evidently flattened, 1.4 times as wide as long, 1.6 times as long as pronotum, with moderately parallel lateral sides (Fig. 45), with widely rounded apical angles (Fig. 52), reaching apical margin of abdominal tergite III, with apical margins slightly oblique toward suture (Fig. 45). Punctation as that in pronotum, slightly sparser in basal portion and near scutellum. Omaliine rove beetles in Eocene Baltic amber 57 Figures 49–53. Paraphloeostiba morosa sp. nov. 49 head and antenna, lateral view 50 head, anteroventral view 51 head and prothorax, ventral view 52 apical part of elytron and abdominal tergites IV–V, dorsal view 53 apex of abdomen and hind legs, ventral view. Abbreviations: a1–a11 = antennomeres 1–11; ai = antennal insertion; alp = apical labial palpomere; bws = brick-wall sculpture on intersegmental membrane; gs = gular suture; ip = intercoxal process; mtm = mentum; mtt = metatibia; s7–s8 = sternites VII–VIII; t4–t6 = tergites IV–VI. Scale bars: 0.2 mm. Legs moderately long and slender, with wide femora and slender tibiae, gradually widened apicad, covered by elongate setae on both inner and outer margins and with a few strong setae on outer margins (Figs 46–48); tarsi short, with small setae on tarsomeres 1–4, apical metatarsomere slightly longer than preceding tarsomeres together; tarsal claws simple, widely curved and elongate (Figs 46, 53). Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 58 Abdomen convex, slightly narrower than elytra, with wide brick-wall sculpture on intersegmental membranes between tergites III–VI (Fig. 52) and sternites III–VI (Fig. 45). Abdominal tergites with moderately dense and deep small punctation and distinct net-like microsculpture (Fig. 52); abdominal sternites with indistinct sparse punctation, with shallow isodiametric microsculpture (Figs 45, 52). Male unknown. Female. Apical margin of abdominal tergite VIII rounded. Apical margin of abdominal sternite VIII broadly concave (Fig. 53). Genital segment with moderately wide apical portions of gonocoxites; shape and length of styli invisible, each with very long seta (Figs 47, 48). Etymology. The specific epithet is the Latin adjective morosus, -a, -um (strange). It refers to somewhat broad body with markedly transverse pronotum of the new species. Remarks. Based on the shape of body and maxillary palpomeres (see also Zanetti 2012: fig. 55l), slightly convex pronotum, punctation and microsculpture of the surface of body, the fossil presumably belongs to the genus Paraphloeostiba. The genus was erected by Steel (1960a) and was compared with Phloeostiba Thomson, 1858 and Phloeonomus Heer, 1839. It differs from Phloeostiba by the shape of short maxillary palpomere 3 and relatively elongate apical palpomere, and from Phloeonomus by a different shape of ligula and maxillary palp (for details see Steel 1960a). Paraphloeostiba includes more than 30 species distributed in the Palaearctic, Madagascan, Nearctic, and predominantly in Oriental, Australian, and Oceanic regions (Steel 1960a; Herman 2001; Shavrin and Smetana 2016; Shavrin 2017b); one species, P. gayandahense (W.J. MacLeay, 1873) is widely adventive around the world to New Zealand, several countries of Europe, and the USA (Herman 2001). The new species is difficult to compare reliably with known species as these mostly differ by the structure of the aedeagus, and shapes of accessory sclerite and spermatheca. The apical antennomeres of P. morosa sp. nov. are slightly transverse, beginning with antennomere 8 (Figs 48, 49) while other known species have transverse antennomeres beginning with 6 or 7. Based on the punctation and microsculpture of the pronotum and shape of antennomere 10 (Fig. 49), the new species is similar to P. specularis (Bernhauer, 1915), known from New Britain (Bismarck Archipelago of Papua New Guinea) but differs by the somewhat larger and wider body, the absence of laterobasal pronotal depressions, and the more transverse pronotum (Fig. 45). Based on the shape and coloration of the body, similar punctation, pronotum without depressions on basal portions, and somewhat convex mesoventrite, P. morosa sp. nov. is also similar to P. electrica Zanetti et al., 2016, recently described from Baltic amber, from which it differs by the wider body with more transverse pronotum, as well as elongate antennomeres 4–7, and wide apical and penultimate palpomeres. Paraphloeostiba requires revision due to unclear morphological boundaries between described species and related genera, as well as many undescribed species from the Oriental and Australian regions deposited in institutional and private collections. The new species is tentatively attributed to this genus, making it the second extinct representative of the genus after P. electrica. Omaliine rove beetles in Eocene Baltic amber 59 Genus Phyllodrepa Thomson, 1859 Type species. Staphylinus floralis Paykull, 1789 †Phyllodrepa daedali Shavrin & Yamamoto, sp. nov. http://zoobank.org/BDE372B6-F773-433D-B98E-C0E272FB8FA7 Figures 7–9, 54–64 Type materials examined. Holotype (male), FMNHINS-3260629, complete specimen as inclusion in very small piece of light yellow Baltic amber, 9.3 mm × 5.9 mm × 2.9 mm in size (Figs 7–9), with the following labels: “16 [printed] 02 [handwritten] SYAC 0 [printed] 294 [handwritten] | Baltic / Burmite | Other: | Larva / Adult | Omalium sp. [handwritten] | Omaliinae [handwritten] | Yantarny, Kaliningrad [handwritten] | Shûhei Yamamoto’s | Amber Collection” <large rectangular label, printed>, “[FMNH barcode at left side of label] FMNHINS | 3260629 | AMBER [handwritten] | FIELD MUSEUM | Wet” <small rectangular label, printed>, “HOLOTYPE | Phyllodrepa | daedali sp. nov. | Shavrin A. & Yamamoto S. des. 2019” <red rectangular label, printed> (FMNH). Preservation. The specimen is relatively well preserved and many details are visible, from the dorsal, ventral and lateral sides (Figs 7–9). However, most body parts, except the dorsal surface of the head, are covered with cloud of milky substance, especially most of the ventral side. Locality and horizon. Baltic amber from Yantarny, Kaliningrad, westernmost Russia; mid-Eocene (ca 44 Ma; Wappler 2005). Description. Measurements: HW: 0.32; HL: 0.22; OL: 0.11; AL: 0.52; PML × PMW (III, IV): III: 0.02 × 0.02, IV: 0.07 × 0.02; PL: 0.35; PW: 0.48; ESL: 0.56; EW: 0.51; MTbL: 0.31; MTrL: 0.20 (I–IV: 0.08; V: 0.12); AW: 0.50; TL: ~1.80. Antennomeres with lengths × widths: 1: 0.08 × 0.03; 2: 0.06 × 0.02; 3–4: 0.05 × 0.02; 5: 0.04 × 0.02; 6: 0.04 × 0.03; 7: 0.03 × 0.03; 8–10: 0.03 × 0.04; 11: 0.08 × 0.04. Body elongate and slightly convex, glossy (Fig. 54), reddish-brown, with darker head and abdomen; mouthparts, antennae, legs and apical margins of abdominal sclerites yellow-brown. Body lateroventrally as in Figure 55 and laterally as in Figure 56. Lateral margins of pronotum (Figs 54, 57), paratergites and abdominal tergite VIII (Fig. 64) with several long erect setae. Head 1.4 times as wide as long, with slightly convex median portion and slight oval lateroapical impressions (Fig. 57), with sparse, small and moderately deep punctation, with shallow postocular carina. Eyes large and broadly convex (Figs 55–57, 60). Ocelli large and convex, situated at level of posterior margins of eyes, distance between ocelli much more than twice as long as distance between ocellus and posterior margin of eye; grooves in front of ocelli present, moderately deep and short (Fig. 57). Apical segment of maxillary palp significantly longer than small penultimate segment, from swollen middle gradually narrowing apicad (Figs 56, 57, 63). Antenna moderately short, just surpassing basal margin of pronotum, with sparse very long setae on antennomeres Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 66 Figures 67–72. Phyllodrepa icari sp. nov. 67 head and pronotum, anterodorsal view 68 left antenna, dorsal view 69 hind legs and abdomen, ventral view 70 left elytron, dorsal view 71 apex of abdomen, dorsal view 72 apex of abdomen, ventral view. Abbreviations: a1–a11 = antennomeres 1–11; bws = brickwall sculpture on intersegmental membranes; gc = gonocoxite; lb = labrum; lp = labial palpi; mp2–mp4 = maxillary palpomeres 2–4; mt5 = metatarsomere 5; mtf = metafemur; mtt = metatibia; mtc = metacoxa; mtv = metaventrite; nk = neck; oc = ocellus; s3–s6 = sternites III–VI; sc = scutellum; st = stylus; t6–t8 = tergites VI–VIII. Scale bars: 0.2 mm. row impunctate longitudinal area (Figs 65, 67). Scutellum large, with triangular apex, without punctures or microsculpture (Fig. 65). Elytra 1.2 times as long as wide, reaching apical margin of abdominal tergite III, slightly widened apicad, with widely rounded apicolateral angles and apical margins truncate at suture (Figs 65, 70). Punctation denser, markedly larger and deeper than that on pronotum, smaller in basal and apical, and sparser in lateral portions. Surface between punctures with dense isodiametric microsculpture. Omaliine rove beetles in Eocene Baltic amber 67 Tarsi long, with apical tarsomere markedly longer than previous tarsomeres together (Figs 66, 69). Abdomen slightly convex, as wide as elytra or slightly wider, intersegmental membranes between tergites IV–VII with brick-wall sculpture (Fig. 65). Abdominal tergites with indistinct small and very sparse punctation and microsculpture, and with sparse and short pubescence, wing-folding patches not visible. Male unknown. Female. First four mesotarsomeres 1–4 without modified setae (Figs 66, 69). Apical margin of abdominal tergite VIII slightly rounded (Fig. 71). Apical margin of abdominal sternite VIII widely concave (Fig. 72). Genital segment with markedly elongate and wide gonocoxites, with very small narrow styli, each with very long seta (Fig. 72). Etymology. The specific epithet is the Latinized name of Icarus (Ikaros), son of Deaedalus in Greek mythology. Remarks. Despite the shape of antennomere 3 and the posterior angles of the pronotum, which are usual in members of the genus Acrolocha Thomson, in other external characters (see details above), the new species belongs to the genus Phyllodrepa. The fossil shares with that genus slightly protruded anterior angles of the pronotum with impressed laterobasal portions (Fig. 67), similar to those of extant North European Ph. sahlbergi Luze, in addition to similar coloration of the body and proportions of antennomeres 4 and 5 (Fig. 68). However, the fossil differs from that species by the significantly smaller and slightly more convex body (Fig. 65), with more prominent eyes (Fig. 67), coarser punctation of the elytra and pronotum, pronotum with less sinuate lateral margins (Figs 65, 67), less transverse antennomeres 6–10 (Fig. 68), and longer elytra (Fig. 70). Based on the shape of its small and pale body, and large and deep punctation of the elytra (Figs 65, 70), Ph. icari sp. nov. is similar to Ph. daedali sp. nov., from which it differs by the paler abdomen, narrow apical maxillary palpomere (Fig. 67), the shape of anterior angles of the pronotum protruding apicad, sparser punctation of the pronotum, distinctly transverse head and pronotum (Fig. 67), shorter antennomeres 4, 5, and 11 (Fig. 58), and shorter elytra. Unnamed species Eusphalerum sp. 1 Figures 14–16, 73–80 Materials examined. 2 males (no. 6, no. 9), 2 females (no. 3, no. 7), 5 unsexed specimens (no. 1, no. 2, no. 4, no. 5, no. 8), FMNHINS-3260631, complete specimens as inclusions in yellow Baltic amber 31.3 mm × 20.6 mm × 12.6 mm in size (Figs 14–16), with the following labels: “15[printed]03[handwritten]-SYAC 00[printed]8[handwritten] | Baltic / Burmite | Other: | Larva / Adult | Omaliinae 11 exs, [handwritten] | Baltic Sea Coast [handwritten] | Axel (Germany) [handwritten] | Shûhei Yamamoto’s | Amber Collection” <large rectangular label, printed>, “Axel Niggeloh” <rectangular label, printed>, “[FMNH barcode at left side of label] FMNHINS | 3260631 | AMBER Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 68 Figures 73–75. Habitus of Eusphalerum sp.1: 73 forebody, dorsal (specimen no. 5) and lateral (specimen no. 6) view 74 pronotum and elytra of specimens no. 1 and no. 2, dorsal view 75 body, lateral view (specimen no. 6). Scale bars: 1.0 mm. [handwritten] | FIELD MUSEUM | Wet” <small rectangular label, printed>, “Eusphalerum | sp. 1 | Shavrin A.V. det. 2018” <rectangular label, printed> (FMNH). Preservation. The specimens are visible from one surface of the piece of amber (specimens were numbered as in Figs 14–16). One of the best preserved specimens (male, no. 6) is located dorsolaterally: the surface of the body, left antenna, and part of the abdomen in lateral view are clearly visible. Eight other specimens are present with differing degrees of visible details. A male (no. 9) is located deep in the piece of amber at the level of its median convexity; its pronotum, elytra, and abdomen are clearly visible dorsolaterally, and the antennae, mouthparts, legs and parts of the thoracic segments and abdomen are visible ventrally. A female (no. 3) is laterally oriented close to the outer surface of the amber piece; its basal antennomeres of the Omaliine rove beetles in Eocene Baltic amber 69 right antenna are partly visible, and the mouthparts, including maxillary and labial palpi, lateral side of the elytra, and partly thoracic sclerites, and legs relatively are visible. Another female (no. 7) is located laterally deep in the piece of amber and, therefore, the dorsal side of its body is visible but strongly cloudy and distorted; details of the structure of maxillary palpus, right antenna, five legs partly, some details of the thorax and abdomen, including apical portion with the genital segment are more or less visible from lateral view. An unsexed specimen (no. 1) is located dorsally near the outer surface of the piece of amber; only the pronotum and elytra are partly visible. Another unsexed specimen (no. 2) is located dorsally near the outer surface of the piece of amber near specimen no. 1; the apical segments of its right antenna, pronotum, and elytra are clearly visible. An unsexed specimen (no. 4) is located a little deeper in the piece of amber, close to specimen no. 3; its hind wings are extended and cover the entire abdomen. The body is not clearly visible except for the pronotum and elytra. An unsexed specimen (no. 5) is located dorsally near specimen no. 6, with the left antenna, posterior portion of head, pronotum, and elytra partially visible. Another unsexed specimen (no. 8) is located deep in the piece of amber, near specimen no. 9, and has its hind wings extended so as to cover the dorsal side of the abdomen; there is a milky covering on the lateral side of the body, and, therefore, the middle and hind legs are only partly visible in lateral view and the pronotum and elytra are partly visible in dorsal view. Syninclusion near outer surface of the piece of amber close to its margin: imago of Diptera about 2.80 mm length, including wings (Fig. 14). Description. Measurements (n = 9): HW: 0.67 (no. 5); HL: ?; OL: 0.18 (no. 6); AL (no. 6): 0.74; PML × PMW: ?; PL: 0.41–0.46; PW: 0.87 (no. 5); ESL: 0.83–0.96; EW: 0.71–0.77; MTbL (no. 8): 0.40; MTrL (no. 8): 0.28; AW: 0.68–0.74; TL: ~2.50– 3.20. Antennomeres with lengths × widths (no. 6): 1: 0.15 × 0.05; 2: 0.08 × 0.04; 3: 0.06 × 0.03; 4–6: 0.05 × 0.03; 7: 0.05 × 0.04; 8: 0.06 × 0.04; 9 0.05 × 0.05; 10: 0.06 × 0.05; 11: 0.08 × 0.05. Body moderately wide, convex (Figs 73–76). Body laterally as in Figures 77 and 79, dorsally as in Figs 73, 74, and 76 and dorsolaterally as in Figure 78. The specimens appear brown to black. Body glabrous, without visible setation. Head transverse, with slightly convex middle portion, without grooves in front of ocelli (Fig. 75); punctation of posterior portion of head irregular, small, and sparse; surface between punctures with relatively large transverse fine microsculpture, distinctly larger and coarser on neck. Eyes large, widely convex (Figs 75, 77). Ocelli relatively small, slightly convex (Figs 73, 75). Apical segment of maxillary palp elongate, slightly narrower and distinctly longer than penultimate segment, from middle gradually narrowed apicad, with moderately acute apex (Fig. 77). Antenna reaching basal margin of elytra; basal antennomere markedly wide, antennomere 2 swollen and slightly elongate, 3 with thin basal portion, slightly widened apicad, antennomeres 4–6 slightly shorter than 3, 7 slightly wider than 6 and 8, 10 slightly transverse in apical portion, apical antennomere wider than penultimate segment, from apical third gradually narrowed apicad (Figs 73, 75, 78, 79). Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 70 Figures 76–80. Eusphalerum sp. 1 76 habitus, dorsal view (specimen no. 4) 77 habitus, lateral view (specimen no. 3) 78 habitus, dorsolateral view (specimen no. 8) 79 habitus, lateral view (specimen no. 9) 80 pronotum and scutellum, dorsal view (specimen no. 1). Scale bars: 1.0 mm (76–79), 0.2 mm (80). Pronotum slightly convex and distinctly transverse, about twice as wide as long, distinctly broader than head, widest in middle, more narrowed posterad than anterad; apical margin slightly rounded, about as broad as posterior margin, anterior (Fig. 75) and posterior angles (Fig. 80) widely rounded; laterobasal margins slightly concave; lateral margins in middle narrowly marginate; median disc of pronotum with very indistinct transverse and laterobasal portions with indistinct wide impressions (Figs 73–76, 80). Pronotum with more or less regular small and sparse punctation, sometimes with wide impunctate longitudinal area on disc, with distinct and moderately large transverse and diagonal microsculpture (Figs 73–76, 80). Scutellum without visible punctures, with distinct isodiametric microsculpture (Figs 73, 74, 76, 80). Omaliine rove beetles in Eocene Baltic amber 71 Elytra slightly convex, distinctly longer than broad, twice as long as pronotum, from middle slightly widened apicad, reaching apical margin of abdominal tergite IV, with widely rounded apical angles and straight apical margin truncated at suture (Figs 73–76, 78). Punctation markedly denser and deeper than that on pronotum, smaller on basal and apical margins and near scutellum; microsculpture as that on pronotum (Figs 73, 74, 76, 78). Abdomen slightly narrower than elytra, with small, moderately sparse punctation and fine indistinct microsculpture. Male. Apical margin of abdominal tergite VIII rounded. Apical margin of abdominal sternite VIII slightly sinuate. Female. Details of shapes of apical abdominal segment not visible. Remarks. The present unique piece of amber contains an interesting and rare aggregation of omaliine specimens which apparently belong to one species. Based on the shape of the body and other structures (antennae, maxillary palpus), features of punctation and microsculpture, etc., the species belongs to Eusphalerini or Omaliini. Tarsi of foreand middle legs are partly visible in one specimen (Fig. 77); tarsi of this specimen has long and indistinctly dense setae on lateral portions of tarsomeres 1–4 that are common in species of the genus Eusphalerum. Based on the shape of the body and other morphological details, and lack of additional morphological data, we have not found similar species among extant representatives of the genus, so we here treat this taxon as Eusphalerum sp. 1. We did not observe sexual dimorphism in the shape of apical portions of the elytra, which often occurs in Eusphalerum, as was observed for Eu. kanti sp. nov. above. Furthermore, the morphology of the aedeagus should be studied, as species of the genus are reliably distinguished by the shapes of the median lobe of the aedeagus and the parameres. Eusphalerum sp. 2. Figures 12, 13, 81–85 Materials examined. One male, complete specimen as an inclusion in a piece of yellow Baltic amber 35.4 mm × 21.5 mm × 7.5 mm in size (Figs 12, 13), with glued very small quadrate paper on plastic bag labeled “AWI | 045”, with the following labels: “AWI-045 | Phyllodrepa (?) | 3 spec.” <rectangular handwritten label>, “Dr. Vitalii Alekseev's | Collection” <rectangular handwritten label>, “Eusphalerum sp. 2 | Shavrin A.V. det. 2018” <rectangular label, printed>. The specimen is deposited in the private collection of Vitalii I. Alekseev (Kaliningrad, Russia), registered as AWI-045. Preservation. The single specimen is a male located close to the outer surface of the piece of amber, with many details visible in both dorsal and ventral surfaces. The elytra are somewhat deformed and seem flattened, and the right elytron is depressed into the thorax. Additionally, the piece of the amber contains two males of Eu. sp. 3 and Eu. sp. 4 (see below), and a syninclusion located near the narrowest side of the amber: nymph of small mite about 0.50 mm in length (Figs 12, 13). Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 72 Figures 81, 82. Habitus of Eusphalerum sp. 2 81 oblique dorsal view 82 dorsolateral view. Scale bars: 1.0 mm. Description. Measurements: HW: 0.53; HL: 0.20; OL: 0.11; AL: 0.69; PML × PMW (III, IV): III: 0.03 × 0.01, IV: 0.07 × 0.02; PL: 0.43; PW: 0.67; ESL: 0.85; EW: 0.81; MTbL: 0.36; MTrL: 0.27 (I–IV: 0.14; V: 0.13); AW: 0.79; TL: 2.06. Antennomeres with lengths × widths: 1: 0.12 × 0.02; 2: 0.07 × 0.02; 3: 0.06 × 0.02; 4: 0.05 × 0.02; 5–6: 0.05 × 0.03; 7: 0.04 × 0.04; 8: 0.05 × 0.04; 9–10: 0.05 × 0.05; 11: 0.10 × 0.04. Body elongate, somewhat flattened (Fig. 81), glossy and glabrous, without visible setation. Body appears dark-brown, with basal portions of pronotum and legs reddishbrown. Body dorsolaterally as in Figure 82 and ventrally as in Figure 83. Head strongly transverse, distinctly more than twice as wide as long, with slightly convex middle portion and posterior parts of infraorbital ridges, without visible grooves in front of ocelli and postocular carina (Fig. 84). Head with indistinct, small and sparse punctation, with moderately coarse and large isodiametric microsculpture between punctures becoming more transverse toward middle part of neck. Eyes large, strongly protruding laterad. Ocelli small, convex, situated very close to infraorbital ridges at level of about middle length of eyes, distance between ocelli about twice as long as distance between ocellus and margin of eye (Figs 82, 84). Labrum transverse. Apical segment of maxillary palp elongate, slightly wider in middle than penultimate segment, from apical third gradually narrowed toward moderately acute apex (Figs 82, Omaliine rove beetles in Eocene Baltic amber 73 Figures 83–85. Eusphalerum sp. 2 83 habitus, ventral view 84 left antenna, head and pronotum, dorsal view 85 abdomen, dorsal view. Scale bars: 1.0 mm (83), 0.4 mm (84, 85). 84). Gular sutures not fully visible, widely separated from each other (Fig. 83). Antenna moderately long, distinctly exceeding shoulders of elytra, with elongate setae, distinctly longer on antennomeres 6–11; basal antennomere wide, gradually widened apicad, antennomere 2 similar in width, swollen and elongate, 3 with thin basal portion, slightly widened apicad, 4 slightly shorter than 3, 5, and 6 slightly wider than 4, 7 short and moderately rounded, 8–10 slightly transverse, apical antennomere more than twice as long as broad, from about middle strongly narrowed toward acute apex (Figs 81–84). Pronotum 1.5 times as wide as long, slightly broader than head, widest in middle, markedly more narrowed posterad than anterad; apical margin slightly and widely rounded, about as broad as posterior margin, anterior and posterior angles widely rounded; laterobasal margins slightly concaved, with very indistinct small crenulation; lateral margins narrowly explanate; lateral portions with indistinct semioval impression about middle (Figs 81, 84). Pronotum with somewhat regular small and sparse punctation and with isodiametric ground sculpture slightly coarser than that on head (Figs 81, 84). Prosternum with moderately wide and protruded prosternal process (Fig. 83). Scutellum large and wide (Fig. 81). Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 74 Elytra little longer than wide, about twice as long as pronotum, gradually widened apicad, reaching basal to apical margins of abdominal tergite IV, with widely rounded apicolateral angles; shoulders moderately widely rounded; lateral edges narrowly explanate (Fig. 81). Punctation of elytra invisible in details but appears slightly denser and deeper than that on pronotum. Legs moderately long and slender, femora markedly widened in middle, tibiae moderately short and thin, gradually widened apicad, slightly shorter than femora, covered by elongate setae, with a few strong setae on apical margins near apex; tarsomeres 1–4 distinctly wide, with dense and long setae; apical metatarsomere long, yet slightly shorter than length of preceding tarsomeres together; tarsal claws simple, elongate (Figs 81–83). Abdomen (Fig. 85) slightly narrower than elytra; abdominal tergites with sparse and moderately small punctures, no wing-folding patches are visible. Male. Apical margin of abdominal tergite VIII slightly rounded. Apical margin of abdominal sternite VIII slightly sinuate. Female unknown. Remarks. As in the previous species, this specimen has very long and moderately dense setae on lateral portions of tarsomeres 1–4, distinctly deformed body (especially elytra) and unusually strongly protruded eyes. Eusphalerum sp. 3 Figures 12, 13, 86, 89 Materials examined. One male, an inclusion in the same piece of the Baltic amber that contains a specimen of Eu. sp. 2 and Eu. sp. 4, with an additional label: “Eusphalerum sp. 3 | Shavrin A.V. det. 2018” (private collection of Vitaly Alekseev (Kaliningrad, Russia), registered as AWI-045). Preservation. The specimen is located dorsolaterally close to the margin of the piece of amber (Figs 12–13). Antennae, lateral potion of the pronotum and elytra with details of the structure of punctation and microsculpture, abdomen and legs (partly) are visible in a dorsal view of the body (Fig. 86); eyes, antennae, some details of thorax, legs and abdomen are relatively visible in a lateral view of the body (Fig. 89). Remarks. This specimen is about 2.30 mm long (Figs 86, 89). It is similar to Eu. kanti sp. nov. and Eu. sp. 4 in the shape of the body, eyes and antennomeres. Because some morphological details of head, pronotum, thoracic sclerites, and legs, as well as punctation and microsculpture, are not visible, we leave this specimen unnamed. Eusphalerum sp. 4 Figures 12, 13, 87–88, 90 Material examined. One male, as an inclusion in the same piece of the Baltic amber that contains Eu. sp. 2 and Eu. sp. 3, with an additional label: “Eusphalerum sp. 4 | Omaliine rove beetles in Eocene Baltic amber 75 Figures 86–90. Eusphalerum spp. (86, 89 Eu. sp. 3; 87, 88, 90 Eu. sp. 4) 86 habitus, dorsolateral view 87 habitus, oblique dorsal view 88 habitus, ventral view 89 habitus, lateral view 90 abdominal apex, ventral view. Scale bars: 1.0 mm (86–89), 0.2 mm (90). Shavrin A.V. det. 2018” (private collection of Vitaly Alekseev (Kaliningrad, Russia), registered as AWI-045). Preservation. The specimen is located with its dorsal side near the widest outer margin of the piece of amber (Figs 12, 13). It is relatively clouded with many details not visible both dorsally (Fig. 87) and ventrally (Fig. 88). Remarks. This specimen is about 2.30 mm long (Figs 87, 88). Based on the relatively narrow body and shapes of antennomeres, as well as the punctation and microsculpture of the forebody, it is similar to Eu. sp. 2. However, we consider this specimen belongs to a different species, because the eyes of this specimen are widely rounded as in Eu. kanti sp. nov. and Eu. sp. 3, and because some details of the body such as dorsal portion of the head and shapes of front and middle tarsi are poorly visible. Apical part of the abdomen (ventral view) as in Figure 90, with sternite VII distinctly emarginated medioapically. Alexey V. Shavrin & Shûhei Yamamoto / ZooKeys 863: 35–83 (2019) 82 Steel WO (1960a) Three new omaliine genera from Asia and Australasia previously confused with Phloeonomus Thomson. Transactions of the Royal Entomological Society of London 112(7): 141–172. https://doi.org/10.1111/j.1365-2311.1960.tb00497.x Steel WO (1960b) A revision of the Phloeocharinae and Omaliinae of New Caledonia (Coleoptera: Staphylinidae). Bulletin de l’Institut royal des Sciences naturelles de Belgique 36 (53): 1–8. Steel WO (1970) The larvae of the genera of the Omaliinae (Coleoptera: Staphylinidae) with particular reference to the British fauna. Transactions of the Royal Entomological Society of London 122(1): 1–47. https://doi.org/10.1111/j.1365-2311.1970.tb00524.x Stork NE (1980) A scanning electron microscope study of tarsal adhesive setae in the Coleoptera. Zoological Journal of the Linnean Society 68(3): 173–306. https://doi. org/10.1111/j.1096-3642.1980.tb01121.x Thayer MK (1985) The larva of Brathinus nitidus LeConte and the systematic position of the genus (Coleoptera: Staphylinidae). Coleopterist Bulletin 39(2): 174–184. https://www. jstor.org/stable/4008131 Thayer MK (2000) Glypholoma larvae at last: phylogenetic implications for basal Staphylinidae? (Coleoptera: Staphylinidae: Glypholomatinae). Invertebrate Taxonomy 14(6): 741–754. https://doi.org/10.1071/IT00019 Thayer MK (2016) 14.7 Staphylinidae Latreille, 1802. In: Beutel RG, Leschen RAB (Eds) Coleoptera, beetles. Vol. 1, morphology and systematics (Archostemata, Adephaga, Myxophaga, Polyphaga partim), 2nd edition. Handbook of Zoology. Arthropoda: Insecta. Walter de Gruyter, Berlin/Boston, 394–442. Thomson CG (1859) Skandinaviens Coleoptera, synoptiskt bearbetade. Tom. I. Lund: Berlingska Boktryckeriet, [5] + 290 pp. https://doi.org/10.5962/bhl.title.138677 Tikhomirova AL (1968) Staphylinid beetles from Jurassic of Karatau (Coleoptera: Staphylinidae). In: Rohdendorf BB (Ed.) Jurassic Insects of Karatau. Akademiya Nauk SSSR, Moscow, 139–154. [in Russian] Tottenham CE (1939) Some notes on the nomenclature of the Staphylinidae (Coleoptera). Parts 1 and 2. Proceedings of the Royal Entomological Society of London (B) 8(12): 224– 226, 227–237. https://doi.org/10.1111/j.1365-3113.1939.tb00483.x Tronquet M (1981) Staphylinidae d’Afghanistan (Coleoptera). Revue Française d’Entomologie (N. S.) 3: 69–83. Tronquet M, Zanetti A (2001) Sur les Eusphalerum Kraatz des Pyrénées françaises. A propos de Eusphalerum anale (Erichson, 1840) et coiffaiti J.P. Nicolas 1974 (Coleoptera, Staphylinidae). Nouvelle Revue d’Entomologie (N.S.) 18(3): 245–248. Tronquet M, Zanetti A (2008) Une nouvelle espèce d’Eusphalerum des Pyrénées. A new Eusphalerum species from the Pyrenees (Coleoptera, Staphylinidae: Omaliinae). Revue de l’Association Roussillonnaise d’Entomologie 17(2): 72–80. Vitali F (2006) About Aenictosoma doenitzi Schaufuss, 1891 (Coleoptera, Cerambycidae, Scydmaenidae). Spixiana 29(2): 99–101. Wappler T (2005) The age of Baltic amber: Could Eckfeld resolve this problem? In: Brothers D, Mostovski M (Eds) Fossils X3, 3rd International Congress of Palaeoentomology with 2nd International Meeting on Palaeoarthropodology and 2nd World Congress on Amber and its Inclusions. Programme and Abstracts, 7th to 11th Feb 2005, Pretoria South Africa. University of Kwazulu-Natal, South African National Biodiversity Institute, Pretoria, 53. Omaliine rove beetles in Eocene Baltic amber 83 Weitschat W, Wichard W (2010) Baltic amber. In: Penney D (Ed.) Biodiversity of Fossils in Amber from the Major World Deposits. Siri Scientific Press, Manchester, 80–115. Wickham HF (1913) Fossil Coleoptera from the Wilson Ranch near Florissant, Colorado. Bulletin from the Laboratories of Natural History of the State University of Iowa 6(4): 3–29. Yamamoto S, Maruyama M (2017) A new genus and species of the rove beetle tribe Mesoporini from Baltic amber (Coleoptera: Staphylinidae: Aleocharinae). Historical Biology 29(2): 203–207. https://doi.org/10.1080/08912963.2016.1144750 Yamamoto S, Maruyama M (2018) Phylogeny of the rove beetle tribe Gymnusini sensu n. (Coleoptera: Staphylinidae: Aleocharinae): Implications for the early branching events of the subfamily. Systematic Entomology 43(1): 183–199. https://doi.org/10.1111/ syen.12267 Zanetti A (1987) Coleoptera. Staphylinidae. Omaliinae. Fauna d’Italia 25. Edizioni Calderini, Bologna, xii + 472 pp. Zanetti A (1992) Contributo alla conoscenza degli Eusphalerum Kr. dei Balcani con descrizione di due nuove specie (Coleoptera, Staphylinidae, Omaliinae). Bollettino del Museo civico di Storia naturale di Verona 16: 347–356 Zanetti A (1993) Contributo alla conoscenza degli Eusphalerum del Caucaso, dell’Anatolia e delle regioni vicine. (Coleoptera, Staphylinidae: Omaliinae). Bollettino del Museo Civico di Storia Naturale di Verona 17 [1990]: 213–263. Zanetti, A (2004) Eusphalerum martinae n. sp. from southern Italy (Coleoptera, Staphylinidae: Omaliinae). Bollettino del Museo regionale di Scienze naturali di Torino 21(2): 487–494. Zanetti A (2012a) New species and new synonymies in the Mediterranean Omaliinae (Coleoptera: Staphylinidae). Bollettino del Museo Civico di Storia Naturale di Verona, 36 (Botanica Zoologia): 55–66. Zanetti A (2012b) Unterfamilie Omaliinae. In: Assing V, Schülke M (Eds) Freude–Harde– Lohse–Klausnitzer – Die Käfer Mitteleuropas. Band 4. Staphylinidae I. Zweite neubearbeitete Auflage. Spektrum Akademischer Verlag, Heidelberg, 49–117. Zanetti A (2014) Taxonomic revision of North American Eusphalerum Kraatz, 1857 (Coleoptera, Staphylinidae, Omaliinae). Insecta Mundi 0379: 1–80. http://journals.fcla.edu/mundi/article/view/0379 Zanetti A, Perreau M, Solodovnikov A (2016) Two new fossil species species of Omaliinae from Baltic amber (Coleoptera: Staphylinidae) and their significance for understanding the Eocene–Oligocene climate. Arthropod Systematics & Phylogeny 74(1): 53–64. http://www.senckenberg.de/files/content/forschung/publikationen/arthropodsystematics/ asp_74_1/03_asp_74_1_zanetti_53-64.pdf Zerche L (1990) Monographie der paläarktischen Coryphiini (Coleoptera, Staphylinidae, Omaliinae). Akademie der Landwirtschaftswissenschaften der Deutschen Demokratischen Republik, Berlin, 413 pp. Zerche L (1992) Zur Taxonomie, Phylogenie und Verbreitung der Hygrogeus-Gruppe Mittelund Zentralasiens (Coleoptera: Staphylinidae: Omaliinae). Annalen des Naturhistorischen Museums in Wien 93(B): 105–142. [1989] Zerche L (2003) Arten der Hygrogeus-Gruppe aus dem Fernen Osten Russlands, aus Japan und China (Coleoptera, Staphylinidae, Omaliinae, Anthophagini). Beiträge zur Entomologie 53(2): 277–295.