Foss. Rec., 22, 111–118, 2019 https://doi.org/10.5194/fr-22-111-2019 © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. The second fossil species of Cathartosilvanus (Coleoptera: Cucujoidea: Silvanidae) from Eocene Baltic amber Vitalii I. Alekseev1,2, Andris Bukejs3, and Ryan C. McKellar4,5,6 1Shirshov Institute of Oceanology, Russian Academy of Sciences, Nahimovskiy prospekt 36, Moscow, 117997, Russia 2Kaliningrad Regional Amber Museum, Marshal Vasilevskii Square 1, Kaliningrad, 236016, Russia 3Institute of Life Sciences and Technologies, Daugavpils University, Vien¯ıbas 13, Daugavpils, 5401, Latvia 4Royal Saskatchewan Museum, 2445 Albert St., Regina, SK, S4P 4W7, Canada 5Biology Department, University of Regina, Regina, SK, S4S 0A2, Canada 6Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA Correspondence: Andris Bukejs ([email protected]) Received: 3 September 2019 – Revised: 2 October 2019 – Accepted: 9 October 2019 – Published: 7 November 2019 Abstract. A new fossil species of the silvanid flat bark bee- The geological backgrounds of the Baltic and Bitterfeld tle genus Cathartosilvanus Grouvelle is described and il- amber deposits have recently been reviewed (Standke, 2008; lustrated from Baltic amber. Cathartosilvanus siteiterralevis Weitschat and Wichard, 2010), and the interconnectedness sp. nov. differs from recent and fossil congeners in the dis- of these deposits has been assessed on the basis of arthro- tinct, sharp denticle found along its posterior pronotal an- pod inclusions (e.g., Hoffeins and Hoffeins, 2003; Szwedo gle. The phenomenon of specific body parts becoming dis- and Sontag, 2013; Dunlop et al., 2018) and geochemistry connected, and the compression of specimens is briefly dis- (Wolfe et al., 2016). Amber from the former Palmnicken cussed and interpreted in the context of amber taphonomy. mine (Yatarny settlement, Kaliningrad, Russia) is part of a The specimen under study appears to be an uncommon case commercially mined deposit of Baltic amber. In the present of a weakly sclerotized beetle imago becoming entrapped in paper, we provide a description of a new species of the genus resin shortly after moulting. Cathartosilvanus from this fossil resin. 2 Material and methods 1 Introduction The material examined is deposited in the palaeontology collection of the Royal Saskatchewan Museum (Regina, Silvanid flat bark beetles have only rarely been reported Saskatchewan, Canada) (RSM). as inclusions from Eocene Baltic amber. Up to now, only Observations of this specimen were made using a Nikon four species have been described, namely Airaphilus den- SMZ745T stereomicroscope. Photographs were taken using ticollis Ermisch, 1942 (probably belonging to Psammoe- a Visionary Digital imaging system, consisting of a Canon cus Latreille, 1829), Dendrobrontes popovi Kirejtshuk, 2011, EOS 5D camera with a Canon MP-E 65 mm macrophotog- Mistran ot Alekseev & Bukejs, 2016, and Cathartosil- raphy lens, attached to an automated camera lift with studio vanus necromanticus Alekseev, 2017. Additionally, Silvanus flash lighting. Extended depth of field at high magnifications sp. and Nausibius sp. have been reported from the Baltic was achieved by combining multiple images from a range amber, and the genus Cryptamorpha Wollaston, 1854 has of focal planes using Helicon Focus 6.8.0 software, and the been mentioned from Eocene Bitterfeld amber (Hope, 1836; resulting images were edited to create figures using Adobe Berendt, 1845; Menge, 1856; Helm, 1896; Handlirsch, 1908, Photoshop CS5. 1925; Klebs, 1910; Bachofen-Echt, 1949; Larsson, 1978; Spahr, 1981; Hieke and Pietrzeniuk, 1984). Published by Copernicus Publications on behalf of the Museum für Naturkunde Berlin. 112 V. I. Alekseev et al.: The second fossil species of Cathartosilvanus from Eocene Baltic amber The following sources were used for the comparison with Type locality recent genera: Halstead (1973), Thomas (1993), and Fried- man (2015). Yantarny settlement (formerly Palmnicken), Sambia (Sam- land) Peninsula, Kaliningrad region, Russia. 3 Systematic palaeontology Etymology Superfamily Cucujoidea Latreille, 1802 The specific epithet is derived from sit ei terra levis, an ancient Latin inscription on tombstones meaning “may the Family Silvanidae Kirby, 1837 Earth rest lightly on you”. The name is used as a noun in Subfamily Silvaninae Kirby, 1837 apposition. Genus Cathartosilvanus Grouvelle, 1912 Diagnosis Note The new species from Baltic amber has the anterior edge of the pronotum almost straight and possesses a single, dis- The studied amber specimen shows the combination of char- tinct, sharp denticle at posterior pronotal angle. In all extant acters unequivocally corresponding to the subfamily Silvan- species of Cathartosilvanus, lateral portions of the prono- inae: subparallel body shape, pentamerous tarsi with tar- tal anterior edge obviously slope backwards to reach antero- somere 4 smallest; closed procoxal cavities; 11-segmented lateral angles within one-third of the edge’s width or less; antennae with distinct antennal club; antennal scape compar- posterior pronotal angles are well-defined or not, but lack atively short, about as long as wide; frons laterally without a sharp denticle anteriorly. Additionally, C. siteiterralevis longitudinal sulcus; and frontoclypeal suture absent. sp. nov. can be distinguished by its weakly undulating prono- The beetle under consideration is assigned to Cathartosil- tal lateral sides (finely denticulate in extant species) and by vanus based on the combination of the following characters: its sparse elytral punctation. (1) lateral sides of pronotum simple, not margined; (2) an- Cathartosilvanus siteiterralevis sp. nov. differs from terolateral denticle on pronotum distinct; (3) all tarsomeres Baltic amber congener C. necromanticus Alekseev in having simple (not lobed and not incrassate); (4) femoral lines open; a distinctly smaller body size (2.3 mm in contrast to 3.5 mm (5) antennomere 8 not narrower than antennomere 7; (6) an- in C. necromanticus); a sharp pronotal denticle at posterior tennae with distinct, three-segmented club; (7) temple well- angle (lacking in C. necromanticus); and sparse, fine prono- defined; and (8) elytral striae not carinate. tal punctation (pronotum is deeply and densely punctate in C. necromanticus). Cathartosilvanus siteiterralevis sp. nov. Figs. 1–3 Description ZooBank: urn:lsid:zoobank.org:act:E1CAFC19- 2BFA- Body length about 2.3 mm, maximum width 0.5 mm; head 4DC1-B828-BF098F2D87F8 length 0.35 mm, head width (including eyes) 0.4 mm; prono- tal length 0.55 mm, pronotal maximum width 0.45 mm; ely- tral length 1.4 mm, elytral maximum width 0.5 mm. Habi- Type material tus elongate, nearly parallel-sided, strongly flattened dorsally Holotype: collection number P3300.87 [RSM]; adult, sex and ventrally; glabrous, elytra and abdomen apparently with unknown. Single beetle included in a transparent, yellow, very fine, short, sparse semi-erect pubescence. Body and ap- round amber piece (with diameter of 8 mm and thickness of pendages unicolour rufous. 2.5 mm); preserved without supplementary fixation. Speci- Head nearly as long as wide, impunctate; forehead al- men is complete, but dorsoventrally compressed (possibly most flat, vertex slightly convex. Labrum with anterior mar- postmortem compression), with almost tripartite body divi- gin widely rounded. Fronto-clypeal suture absent. Com- sion between head, prothorax, and the rest of body. Synin- pound eyes relatively small and prominent, hemispherical, clusions: few stellate fagacean trichomes, fragments of un- with coarse facets; eyes widely separated, with distance be- × known insect, and two small detritus particles. tween eyes about 6 transverse diameter of one eye. Temple very short, length about 0:3× eye length; posterior outer an- Type strata gle of temple acute and pointed. Antennal grooves absent. Mandibulae bidentate apically. Baltic amber from Eocene amber-bearing blue Earth layers Maxillary palpi short; terminal palpomere elongate, (mostly Bartonian age is interpreted for the extinct central spindle-shaped, truncate, about 2× as long as penultimate European resin-producing forests according to Bukejs et al., palpomere. Antenna short, extending to middle of pronotum; 2019). gradually thickening toward apex; 11-segmented, with indis- Foss. Rec., 22, 111–118, 2019 www.foss-rec.net/22/111/2019/ V. I. Alekseev et al.: The second fossil species of Cathartosilvanus from Eocene Baltic amber 113 Figure 1. Cathartosilvanus siteiterralevis sp. nov., holotype, P3300.87 (RSM): (a) habitus, dorsal view; (b) habitus, ventral view; (c) habitus, lateral view. Scale bars D 1 mm. www.foss-rec.net/22/111/2019/ Foss. Rec., 22, 111–118, 2019 114 V. I. Alekseev et al.: The second fossil species of Cathartosilvanus from Eocene Baltic amber Figure 2. Cathartosilvanus siteiterralevis sp. nov., holotype, P3300.87 (RSM): (a) details of forebody, dorsal view; (b) abdomen, ventral view. Scale bars D 0:5 mm. Abbreviations: D: sharp denticle at posterior pronotal angle; FL: femoral line. Foss. Rec., 22, 111–118, 2019 www.foss-rec.net/22/111/2019/ V. I. Alekseev et al.: The second fossil species of Cathartosilvanus from Eocene Baltic amber 115 Figure 3. Cathartosilvanus siteiterralevis sp. nov., dorsal outline reconstruction of forebody. Scale bar D 0:5 mm. tinct club apparently composed of three segments; sparsely cle at posterior angle, and with obtuse denticle anterolater- covered with fine semi-erect