(Hymenoptera, Formicidae) from the Late Eocene Rovno Amber Author(S): Alexander Radchenko and Gennady M
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Boltonidris Gen. Nov., the First Extinct Stenammini Ant Genus (Hymenoptera, Formicidae) from the Late Eocene Rovno Amber Author(s): Alexander Radchenko and Gennady M. Dlussky Source: Annales Zoologici, 62(4):627-631. 2012. Published By: Museum and Institute of Zoology, Polish Academy of Sciences DOI: http://dx.doi.org/10.3161/000345412X659687 URL: http://www.bioone.org/doi/full/10.3161/000345412X659687 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. A N N A L E S Z O O L O G I C I (Warszawa), 2012, 62(4): 627-631 BOLTONIDRIS GEN. NOV., THE FIRST EXTINCT STENAMMINI ANT GENUS (HYMENOPTERA, FORMICIDAE) FROM THE LATE EOCENE ROVNO AMBER ALEXANDER RADCHENKO1 and GENNADY M. DLUSSKY2 1Museum and Institute of Zoology Polish Academy of Sciences, Wilcza 64, 00-679, Warszawa, Poland; e-mail: [email protected] 2Moscow State University, Biological Faculty, Cathedra of the Theory of Evolution, Vorob'evy gory, 119899, Moscow, Russia; e-mail: [email protected] Abstract.— The new extinct ant genus and species, Boltonidris mirabilis, are described from the late Eocene Rovno Amber (Ukraine). This genus belongs to the tribe Stenammini of the subfamily Myrmicinae. It possesses the plesiomorphic characters of the tribe Stenammini, e.g. 12-segmented antennae with 3-segmented apical club, characteristic structure of the clypeus and frontal lobes, absence of gastral shoulder, but it has a series of autapomorphies, e.g. modified mandibles with the only two teeth on the masticatory margin, well developed longitudinal medial groove on the head dorsum, somewhat depressed areas lateral to the frontal carinae (like "vestigial" antennal scrobes), and finely swollen postero-lateral area of head, close to the occipital corners. Additionally, it has two short blunt teeth on the pronotum. Key words.— Boltonidris mirabilis, ants, taxonomy, Formicidae, Myrmicinae, Stenam- mini, palaeontology, European ambers, Ukraine, late Eocene, new genus, new species. INTRODUCTION At the same time, diversity of the subfamily Myrmic- inae in all European ambers is low: only 12 genera, The ant fauna of the late Eocene European ambers comprising just 20 species, are known (this total (ca. 40 Mya) is the best studied among all fossil global excludes Agroecomyrmex Wheeler, which was trans- myrmecofaunas. Up to now, more than 17,000 ant spec- ferred to the subfamily Agroecomyrmecinae by Bolton imens have been examined in these ambers, and this 2003, 2011). Moreover, no new myrmicine genera or material includes more than 170 species from 63 gen- even species were described from the European late era and 15 subfamilies (the subfamily concept is treat- Eocene ambers between the time of Wheeler’s (1915) ed according to Bolton 2003). Material from the Baltic monographic revision of the ants of Baltic Amber and Amber is the richest and the best studied – it includes the beginning of twenty-first century. However, in the ca. 75% of all ant specimens found in the European late last decade we were fortunate to gain access to the rich Eocene ambers. However, intensive accumulation and new amber collections from the Baltic, Bitterfeldian investigation of the ant material from the Rovno Amber (= Saxonian), Scandinavian (= Danish), and Rovno (western Ukraine) was started in the last decade or so ambers. As a result, we described several new species (see review of Perkovsky et al. 2007), and in total more from the different ant subfamilies, including Myrmici- than 60 species from about 30 genera have now been nae, and even described four new myrmicine genera found in the Rovno Amber (Dlussky and Rasnitsyn (Dlussky 2002a, 2002b, 2008a, 2008b, 2009, 2010, 2009, our unpublished data). Dlussky and Perkovsky 2002, Dlussky and Radchenko PL ISSN 0003-4541 © Fundacja Natura optima dux doi: 10.3161/000345412X659687 628 A. RADCHENKO and G. M. DLUSSKY 2006a, 2006b, 2009, 2011, Radchenko et al. 2007, Rad- Indices: chenko and Perkovsky 2009). Consequently, 17 myr- CI = HL/HW, micine genera are known nowadays from the late FI = FW/HW, Eocene European ambers. FLI = FLW/FW, Below we describe one more new myrmicine genus, SI1 = SL/HL, Boltonidris, and place it in the tribe Stenammini. This SI2 = SL/HW, tribe contains 17 genera, most of which are distributed PI = PL/PH, in the Old World tropics and partly subtropics, though PPI = PPL/PPH; three genera are Neotropical. Only Stenamma West- ESLI = ESL/HW; wood can be considered as the predominantly Holarc- OI = OL/HW. tic genus, and while it penetrates to the Neotropical and Oriental Regions, it is absent in the Afrotropical Region and in Australia. Among Stenammini genera only species of Stenamma and Vollenhovia Mayr are TAXONOMY found in the Baltic Amber, all other genera are repre- sented by extant species. Thus, Boltonidris is the first Boltonidris gen. nov. known extinct genus of Stenammini. Type species. Boltonidris mirabilis sp. nov., by monotypy. Etymology. Dedicated to the distinguished British MATERIAL AND METHODS ant taxonomist, Dr. Barry Bolton. Differential diagnosis. We place Boltonidris in We examined one worker (holotype) in a piece of the tribe Stenammini (sensu Bolton, 2003). It differs Rovno amber that is preserved in the Shmalhausen distinctly from the Stenammini genera that have no Institute of Zoology of the Ukrainian National Academy antennal scrobes (e.g. Stenamma, Rogeria Emery, of Sciences, Kiev (SIZK). Vollenhovia Mayr, etc.) by the structure of the man- The figures are based on the photographs made dibles, by the presence of the blunt horn-like teeth on using an Olympus Camedia C-3030 digital camera fitted pronotum, and by the presence of a distinct longitudi- to an Olympus SZX9 microscope in conjunction with nal medial groove on head dorsum. the computer program CorelDraw 8. Description. Head slightly widened posteriorly, Not all features were easily visible and measurable with very weakly convex sides, occipital margin slight- on the examined specimen; hence we measured only ly concave medially; head dorsum with distinct longitu- visible details (accurate to 0.01 mm). dinal medial groove running from occipital margin to Measurements: frontal triangle; antennae 12-segmented, with distinct HL –length of head in dorsal view, measured in 3-segmented club; median portion of clypeus narrowed a straight line from the anterior point of medi- from side to side and elevated; this elevated part with an clypeal margin to mid-point of the occipital two lateral longitudinal carinae; frontal lobes narrow, margin, sub-vertical, partly cover antennal sockets; frons nar- HW – maximum width of head in dorsal view, row, antennal sockets quite closely approximated; FW – minimal distance between frontal carinae, antennal scrobes absent; eyes present, but small; FLW –maximal distance between outer borders of mandibles triangular, quite stout, with well developed frontal lobes, masticatory margin, which possesses a relatively long OL – maximal diameter of eye, apical tooth and single very small triangular preapical SL –maximum straight-line length of antennal denticle only; propodeum with sharp spines, pronotum scape seen in profile, with short, blunt horn-like teeth. AL – diagonal length of the alitrunk seen in profile, from the neck shield to the posterior margin of metapleural lobes, Boltonidris mirabilis sp. nov. PNW – maximal width of pronotum, (Figs 1–4) ESL – length of propodeal spine, HTL – length of tibia of hind leg, Etymology. From Latin “mirabilis” – wonderful, PL – maximum length of petiole from above, extraordinary. PH – maximum height of petiole in profile, Material examined. Holotype worker, Rovno Am- PPL – maximum length of postpetiole from above, ber, late Eocene, complete specimen, No. K-3581 (SIZK). PPH – maximum height of postpetiole in profile, Description. Worker. Head somewhat longer than GL – length of gaster. broad, slightly widened posteriorly, with very feebly BOLTONIDRIS GEN. NOV., THE FIRST EXTINCT STENAMMINI ANT GENUS FROM THE LATE EOCENE ROVNO AMBER 629 Figures 1–2. Photographs of the holotype worker of Boltonidris mirabilis. (1) body, dorso-lateral view; (2) head, dorsal view. Scale bars – in mm. convex sides, very shallowly concave occipital margin small, with ca. 15 ommatidia, situated distinctly in and rounded occipital corners. Head dorsum flattened front of the mid-length of head. Scape relatively long, and with a well developed median longitudinal groove. almost reaching occipital margin, gradually but strong- Frontal lobes slightly extended, sub-vertical, quite ly curved at the base, without any trace of additional closely approximated, partly covering antennal sock- structures on the bend. Anterior clypeal margin gradu- ets.