The oldest osoriine rove beetle from Cretaceous Burmese amber (Coleoptera: Staphylinidae)

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    the antiquity of the subfamily, but also bears signicant biogeographic implications. 2014 Elsevier Ltd. All rights reserved.

    speciehe mobennike beetxcept

    Sinolispinodes torosus Zhang, from the Miocene in Shanwang ofShandong Province, China. Sinolispinodeswas then transferred fromOxytelinae to Osoriinae as supported by the absence of paratergiteson abdominal segments (Herman, 2001; Yue et al., 2010). Irmler

    y history of Osor-

    lder osoriine rovei et al., 2012) as ar. Based on UePbca. 99 Ma) for thelished (Shi et al.,of the previouslydest record for the

    subfamily Osoriinae.

    2. Material and methods

    The material described here derives from amber deposits inthe Hukawng Valley of northern Myanmar. The mining is done ata hill named Noije Bum near Tanai Village (2621033.4100N,9643011.8800E) (e.g., Cruickshank and Ko, 2003; Grimaldi et al.,2002). Observations and photographs were taken using a Zeiss

    * Corresponding author. State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39East Beijing Road, Nanjing 210008, China.

    Contents lists availab

    Cretaceous

    els

    Cretaceous Research xxx (2014) 1e6E-mail address: caichenyang1988@163.com (C. Cai).abdominal segment (Newton et al., 2000). Although a few otherstaphylinids, including certain genera of Euaesthetinae, Paederinae,Tachyporinae and some Stenus species, have unmargined abdomen,they can be easily separated from Osoriinae by having slender,more or less falcate mandibles lacking molar lobes and concealedantennal insertions (Newton et al., 2000).

    Fossil osoriines are relatively rare, and all of them are limited tothe Tertiary (Hope, 1837; Irmler, 2003; Ortega-Blanco et al., 2013;Zhang, 1989). Zhang (1989) described a fossil oxyteline species,

    been reported. The origin and early evolutionariinae thus remain unclear.

    Herein, we report a discovery of a much obeetle (ca. 99 million years old; see details in Shnew genus from the Cretaceous Burmese ambedating of zircons, an earliest Cenomanian age (fossilized inclusions in Burmese amber is estab2012). The new fossil, about twice the ageknown Eocene fossil from India, represents the ol2001; Thayer, 2005). The subfamily Osoriinae is a very distinctivegroup among Staphylinidae, which lacks paratergites on each

    Eocene amber of India, which is regarded as the oldest known fossilof Osoriinae. Until now, no fossil osoriines of Mesozoic age haveCretaceousBurmese amber

    1. Introduction

    With more than 2083 describedrove beetle subfamily Osoriinae is tOxyteline group of subfamilies (GreThayer, 2005). Modern osoriine rovuted in all biogeographic regions ehttp://dx.doi.org/10.1016/j.cretres.2014.03.0200195-6671/ 2014 Elsevier Ltd. All rights reserved.

    Please cite this article in press as: Cai, C., HuaCretaceous Research (2014), http://dx.doi.ors and 103 genera, thest diverse group of theov and Newton, 2012;les are widely distrib-the Antarctic (Herman,

    (2003) described an extinct genus Lispinomimus Irmler, twoextinct species (Thoracophorus palaeobrevicristatus Irmler andNacaeus dominicanensis Irmler), and ve unnamed species ofgenera Liberiana Blackwelder, Osoriellus Fagel, and Neosorius Fagelfrom the Early Miocene Dominican amber. Recently, Ortega-Blancoet al. (2013) described a new genus and species, Paleosorius cam-bayensis Ortega-Blanco, Chatzimanolis and Engel, from the EarlyOsoriinaeThoracophoriniStaphylinidaelong antennae, very long maxillary palpomere 4, contiguous procoxae, and well-developed anterolateralpronotal angles. The new discovery of the oldest Osoriinae from about 99 million years not only suggestsThe oldest osoriine rove beetle from Cre(Coleoptera: Staphylinidae)

    Chenyang Cai a,b,*, Diying Huang a

    a State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology aRoad, Nanjing 210008, ChinabGraduate School, University of Chinese Academy of Sciences, 19A Yuquanlu, Beijing 10

    a r t i c l e i n f o

    Article history:Received 4 December 2013Accepted in revised form 17 March 2014Available online xxx

    Keywords:

    a b s t r a c t

    A remarkable new genusgured based on a well-prfrom Myanmar. Mesallotroincluding the protibia witcoxal cavities, and more or

    journal homepage: www.ng, D., The oldest osoriine rovg/10.1016/j.cretres.2014.03.02ceous Burmese amber

    alaeontology, Chinese Academy of Sciences, 39 East Beijing

    , China

    species, Mesallotrochus longiantennatus n. gen. n. sp., is described andrved individual in the lowermost Upper Cretaceous (Cenomanian) amberis placed in the extant tribe Thoracophorini based on its general habitus,ner edge straight, without ctenidium, exposed protrochantins, open pro-s atted body. Mesallotrochus is separated from other allied genera by the

    le at ScienceDirect

    Research

    evier .com/locate/CretRese beetle from Cretaceous Burmese amber (Coleoptera: Staphylinidae),0

  • Discovery V20 stereo microscope and a Zeiss Axio Imager 2 lightmicroscope with a digital camera attached. Photomicrographs withgreen background (Fig. 3) are taken using green uorescence aslight source attached to a Zeiss Axio Imager 2 light microscope. Thematerial has been prepared, including cut with a razor bladeand polished with sand papers with different grain sizes andwith diatomite mud. A polished slab of amber measuring3.5 mm 2.8 mm contains the beetle specimen, which (in dorsalview) is oriented at approximately a 40 angle to the surface.

    3. Systematic palaeontology

    Order: Coleoptera Linnaeus, 1758Family: Staphylinidae Latreille, 1802Subfamily: Osoriinae Erichson, 1839Tribe: Thoracophorini Reitter, 1909Subtribe: Clavilispinina Newton and Thayer, 1992

    Genus: Mesallotrochus gen. nov.

    Type speciesMesallotrochus longiantennatus sp. nov., here designated.

    EtymologyThe genus name is a combination of Meso-, meaning Mesozoic,

    and the supposed related genus Allotrochus; it is masculine ingender.

    DiagnosisSmall, slightly attened Staphylinidae with: eyes moderate,

    distinctly protruding, coarsely faceted; antennal insertions con-cealed; antennae densely setose, not clubbed, long, extending

    widest nearly at middle, with lateral carinae, anterolateral pronotalangles well-developed; elytra longer than pronotum, covering partof abdominal tergite III, with epipleural keels; protrochantinsexposed; pro- and metacoxae contiguous; mesocoxae narrowlyseparated; femoraweakly dilated, somewhat atted, with relativelydeep concave groove in ventral side to conceive tibia; tibiae veryslender, without strong spins; all tarsi 5-segmented; abdominalsegments IIIeVIII well-developed, without paratergites, tergiteswithout basolateral ridges.

    Mesallotrochus longiantennatus sp. nov. (Figs. 1e4).

    EtymologyDerived from the combination of the Latin adjectives longus and

    antennatus, meaning with (or having) long antennae.

    MaterialHolotype, NIGP157737. The fossil beetle is a completely pre-

    served adult. The type specimen is housed in the Nanjing Instituteof Geology and Palaeontology, CAS, Nanjing, China.

    OccurrenceLowermost Upper Cretaceous (ca. 99Ma) amber from the village

    of Tanai, Hukawng Valley, northern Myanmar.

    DiagnosisAs for the genus (vide supra).

    DescriptionBody: 2.86 mm long; sub-parallel, deep brown throughout.Head: relatively small, 0.43 mm long and 0.51 mm wide

    (including eyes), without lateral or dorsal neck constriction; withfour long setae at apical margin of frons; antennal insertions con-

    C. Cai, D. Huang / Cretaceous Research xxx (2014) 1e62beyond posterior margin of pronotum; maxillary palpi long, withreduced palpomere 3 and elongate article 4; pronotum transverse,Fig. 1. General habitus of Mesallotrochus longiantennatus n. gen. n. sp., holotype, NIG

    Please cite this article in press as: Cai, C., Huang, D., The oldest osoriine rovCretaceous Research (2014), http://dx.doi.org/10.1016/j.cretres.2014.03.02cealed under shelf-like corner of frons, located before a line drawnP157737. A. dorsal view; B. ventral view. Under normal light. Scale bars: 1 mm.

    e beetle from Cretaceous Burmese amber (Coleoptera: Staphylinidae),0

  • ousC. Cai, D. Huang / Cretacebefore anterior margin of eye. Eye positioned laterally. Antennaelong (Fig. 2B; 3A), 11-segmented, moniliform; antennomeres 1broad and elongate, antennomere 2 elongate, slightly narrowerthan antennomere 1, antennomere 3 gradually dilated to apex,nearly as long as antennomere 2, antennomeres 4e7 graduallywidened, antennomere 8 slightly smaller than 7 and 9, anten-nomere 10 almost in the same size and shape as 9, antennomere 11conical, 1.6 times as long as antennomere 10. Labrum and labialpalpus not observable. Mandibles with sharp apex visible. Maxil-lary palpus (Fig. 2A) relatively long, apparently 4-segmented, pal-pomere 2 longer than wide, palpomere 3 as wide as 2, but shorterthan 2, palpomere 4 elongate, about 2.8 times as long as palpomere3, glabrous.

    Thorax: Pronotum wider than head. 0.69 mm wide, 0.54 mmlong. Pronotum in dorsal view slightly narrowed from middle tobase; anterior margin concave, posterior margin nearly straight.Anterolateral angels distinctly pronounced, posterolateral angelsrectangular. Pronotum with well-developed lateral carina. Pros-ternum transverse, procoxae contiguous (Fig. 3B), with a smallprosternal process; procoxal cavities open. Pronotal hypomerondeveloped, subtriangularly produced inwards. Mesocoxae narrowlyseparated by smaller mesoventral and larger metaventral processes(Fig. 3B); metacoxae contiguous. Mesoscutellum sub-triangular,longer than wide, distinctly narrowed at anterior third. Elytraelongate, sub-parallel, 0.75 mm long and each 0.44 mm wide,

    Fig. 2. Enlargements of Mesallotrochus longiantennatus n. gen. n. sp., under normal lightpalpomere; B. details of right antenna with maxillary palpus partly shown; C. enlargementand mesotarsus, note the single long seta on tarsomeres 1e4; E. enlargement of metatarsu

    Please cite this article in press as: Cai, C., Huang, D., The oldest osoriine rovCretaceous Research (2014), http://dx.doi.org/10.1016/j.cretres.2014.03.02Research xxx (2014) 1e6 3partly covering abdominal tergite III; surfacewithout striae, carinaeor microsetae; hind margin truncate. Epipleural keel present. Hindwings fully developed, with setae forming fringe alongmargin. Legsrelatively long; protrochantins exposed; procoxae small, rounded,protrochanters small, profemora clavate and atted, protibiaeelongate, slightly narrowed to apex, protarsi 5-segmented (Fig. 2A,C; 3B), protarsomeres 1e4 short, almost in same shape and size,each with long setae in ventral side, tarsomere 5 elongate; meso-tibiae slender, longer than protibiae, mesotarsi 5-segmented(Fig. 2D; 3A), mesotarsomere 1 longer than wide, tarsomeres 2e4shorter, almost in same shape and size, each with long setae inventral side; metacoxae sub-triangular, without metacoxal plate,metafemora robust, larger than mesofemora, metatibiae slender,metatarsi 5-segmented (Fig. 2E). All tarsomeres 2e4 lobed in dorsalview. Pretarsal claws simple; empodium bisetose.

    Abdomen: narrow, sub-parallel, with long setae at lateralmargin. Abdominal tergite III partly covered by elytra. All segmentswithout paratergites. Basolateral ridges absent. Wing-foldingpatches absent. Abdominal segment VII long, segment VIII retrac-ted to segment VII; tergite and sternite VIII sub-triangular.

    4. Discussion

    Among the 32 extant and one extinct subfamilies of Staph-ylinidae (Newton et al., 2000), the newgenus and species described

    . A. Enlargement of right maxillary palpus and left protarsus, showing the elongateof protibia and protarsus, note the lobed tarsomeres 2e4; D. enlargement of mesotibias and partial metatibia. Scale bars: 500 mm in B, 200 mm in others.

    e beetle from Cretaceous Burmese amber (Coleoptera: Staphylinidae),0

  • ousC. Cai, D. Huang / Cretace4here is easily placed in the Osoriinae based on its general habitus,including parallel and elongate body shape, antenna inserted infront of eyes and under shelf-like corner of frons, 5-segmented tarsiwith elongate tarsomere 5,11-segmented non-clavate antenna, andmore importantly, on the presence of unmargined abdominalsegments, i.e., entirely without paratergites (Newton et al., 2000).The subfamily Osoriinae currently comprises four tribes, viz. Eleu-sinini Sharp, Leptochirini Sharp, Osoriini Erichson, and Thor-acophorini Reitter (Bouchard et al., 2011). The new genusMesallotrochus is easily separated frommembers of the remarkabletribe Leptochirini by its general habitus, especially the absence ofmodications in cephalic characters and posteriorly open procoxalcavities. Mesallotrochus cannot be confused with the genera of thetribe Eleusinini based on the slightly (not extremely) attenedbody, very slightly (not greatly) basally narrowed pronotum, small(not larger than pronotum) head, relatively large procoxae, andsmall (not greatly enlarged) protrochantins. Mesallotrochus differsfrom members of Osoriini by lacking deep groove and carina onmesal surface of procoxae, protibia with concave and ctenidium-bearing inner edge, or convex body. The new genus is condentlyattributed to the modern tribe Thoracophorini as supported by theabsence of ctenidium on inner edge of protibia and the more or less

    Fig. 3. Enlargements of Mesallotrochus longiantennatus n. gen. n. sp., under green uorescenenlargement of pro- and mesothorax, showing contiguous procoxae and separated meso200 mm.

    Please cite this article in press as: Cai, C., Huang, D., The oldest osoriine rovCretaceous Research (2014), http://dx.doi.org/10.1016/j.cretres.2014.03.02Research xxx (2014) 1e6atted body (e.g., Irmler, 2010; Newton et al., 2000). The tribeThoracophorini includes four extant subtribes: ClavilispininaNewton and Thayer, Glyptomina Newton and Thayer, LispininaBernhauer and Schubert, and Thoracophorina Reitter (Newtonet al., 2000). Mesallotrochus is easily separated from members ofthe subtribe Glyptomina by having exposed protrochantins; fromThoracophorina by having exposed protrochantins and the absenceof any carinae on head, pronotum or elytra. Mesallotrochus super-cially resembles certain genera belonging to the extant subtribesClavilispinina and Lispinina. However, it can be ruled out fromLispinina by its contiguous procoxae, which are not well separatedby a distinct prosternal process as in Lispinina. Therefore, Mesal-lotrochus is readily placed in the recent subtribe Clavilispinina onthe basis of the general adult morphology, including the contiguousprocoxae. There are nine extant genera included in the Clav-ilispinina (Herman, 2001). Among the nine genera, Mesallotrochusclosely resembles Allotrochus Fagel and Myrmelibia Newton inhaving small head and transverse pronotum (Newton, 1990). Spe-cically, it shares with the Australia-endemic myrmecophilousMyrmelibia the elongate antennae (extending beyond the posteriormargin of pronotum) and transverse pronotum with pronouncedanterolateral angels, but it differs from the later by longer

    ce. A. Enlargement of left antenna (dorsal view) with maxillary palpus partly shown...

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