2020 ACTA ENTOMOLOGICA 60(1): 397–409 MUSEI NATIONALIS PRAGAE doi: 10.37520/aemnp.2020.24 ISSN 1804-6487 (online) – 0374-1036 (print) www.aemnp.eu RESEARCH PAPER A review of Gnathoncus of Southeast Asia (Coleoptera: Histeridae: Saprininae) Tomáš LACKNER Bavarian State Collection of Zoology, Münchhausenstraße 21, DE-81247 Munich, Germany; e-mail: [email protected] Accepted: Abstract. Six species of the genus Gnathoncus Jacquelin du Val, 1857 occur in the region of 18th May 2020 Southeast Asia: G. brevisternus Lewis, 1907, G. semimarginatus Bickhardt, 1920, G. viet- Published online: namicus Kryzhanovskij, 1972, G. rotundatus (Kugelann, 1792), G. nannetensis (Marseul, 19th June 2020 1862), and the newly described G. sechuanus sp. nov. (China: Sichuan). Two rare species, G. brevisternus and G. semimarginatus, are redescribed; all species are fi gured and keyed. The lectotype of Gnathoncus brevisternus is designated and the species is newly reported from Vietnam and Nepal. Key words. Coleoptera, Histeridae, Saprininae, Gnathoncus, lectotype designation, new species, Southeast Asia Zoobank: http://zoobank.org/urn:lsid:zoobank.org:pub:AC387BAF-E7A8-40B2-9486-E5642074587D © 2020 The Author. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Licence. Introduction region. Gnathoncus rotundatus (Kugelann, 1792) is a Gnathoncus Jacquelin du Val, 1857 is a monophyletic synanthrope widespread worldwide, and G. nannetensis (L et al. 2019) and predominantly Holarctic genus (Marseul, 1862) is widespread in the Palaearctic Region containing 25 species worldwide (M 2011, V but also reaching Southeast Asia (L et al. 2015; & R 2013). Most of its species are distributed in the M 2011). Two of the endemic species, G. brevister- Holarctic Region, with only singletons known from the nus and G. semimarginatus, have been known only from Afrotropical (one autochthonous species) or Oriental holotypes so far. Gnathoncus vietnamicus Kryzhanovskij, Regions (three autochthonous species; M 2011). 1972, occurring in Vietnam and Thailand, is known only Gnathoncus members are often collected inside bird from female specimens. A female of an unidentifi ed species nests, mammal burrows, on (bat) guano in caves, but are of Gnathoncus has been reported from Java (Indonesia; also found occasionally on (bird) carcasses, in dung and Ô H 2008). In the present contribution, all on excrements, or in decaying organic matter (L species are keyed and fi gured and the two rare Southeast 2010). Several species have been distributed all over the Asian endemics are re-described. One new species from world by human activity (see below). The recently pub- Sichuan (China) is described. lished molecular phylogeny of the subfamily Saprininae (L et al. 2019) revealed Gnathoncus as a member of Material and methods the earliest-branching clade, together with Aphelosternus Wenzel, 1962, Tomogenius Marseul, 1862, Saprinodes The region of Southeast (SE) Asia basically corre- Lewis, 1891, and Myrmetes Marseul, 1862. Gnathoncus sponds to the Oriental Region of L L (2015), and Myrmetes are likewise well defi ned by morphological but with several Chinese provinces included, and is here synapomorphies (see L 2010, L & L defi ned as the following territory: Nepal, Bangladesh, 2017). In the Southeast Asia, only three autochthonous Bhutan, India, Sri Lanka, China (Sichuan, Yunnan, and two widely distributed species of the genus have Guangxi, Guangdong, Hainan, Fujian, Jiangxi, Hunan, been reported hitherto. Three of them (G. brevisternus Huizhou, Chongqing), Taiwan, the Philippines, Thailand, Lewis, 1907, G. vietnamicus Kryzhanovskij, 1972 and Laos, Myanmar, Vietnam, Indonesia, Singapore, Malay- G. semimarginatus Bickhardt, 1920) are endemic for the sia, Timor-Leste and Brunei. Dry-mounted specimens Lackner.indd 397 19.06.2020 8:18:55 398 LACKNER: Review of Gnathoncus of Southeast Asia (Coleoptera: Histeridae) were relaxed in warm water for several hours. After se, pronotum only with marginal pronotal stria (shortened removal from original cards, they were side-mounted in case of G. semimarginatus); elytra with complete striae on a triangular point and examined under a Nikon 102 I–IV; between base of elytral stria IV and sutural elytral binocular microscope with diff use light. Male genitalia stria (that can be interrupted or present only as a short basal were fi rst macerated in 10% KOH solution for about three fragment) present a characteristic short, hooked appendix; hours, afterwards cleared in 80% alcohol and macerated lateral prosternal striae very short, reaching approximately in lactic acid with fuchsine, incubated at 60ºC for another mid-length of carinal prosternal striae; outer lateral costa of 30 minutes, and subsequently cleared in 80% alcohol and prosternal process reaching prosternal keel. Ninth tergite then observed in α-terpineol in a small glass dish. SEM of male terminalia longitudinally divided; VIII sternite and micrographs were taken with a JSM 6301F microscope tergite not fused laterally. For a key to the Thai Saprininae at the laboratory of Faculty of Agriculture, Hokkaido see M Ô (2003); for a key to the Indonesian University, Sapporo, Japan. Digital photographs of male Saprininae see Ô H (2008). As yet, there is genitalia were taken by a Nikon 4500 Coolpix camera and no key to the SE Asian genera of Saprininae, mostly due edited in Adobe Photoshop CS5. Based on the photogra- to the existence of undescribed taxa from Thailand and phs or direct observations, the genitalia were drawn using Vietnam (T. Lackner, unpublished). a light-box Hakuba klv-7000. Adult images were prepared Biology. Gnathoncus brevisternus was collected inside by Mr. František Slamka (Bratislava, Slovakia). Speci- caves; G. rotundatus is a synanthrope often collected in mens were measured with an ocular micrometer. Species anthropogenic settings; G. nannetensis was collected on of Gnathoncus in this work are listed alphabetically. carrion and in bird nests; G. sechuanus sp. nov. was col- Body part terminology follows that of Ô (1994) lected under a mushroom on a tree trunk in a mixed forest. and L (2010) and the following abbreviations of The biology of two SE Asian endemics (G. vietnamicus morphological measurements are used: and G. semimarginatus) is unknown. APW width between anterior angles of pronotum Distribution. In SE Asia, Gnathoncus is present mainly EL length of elytron along elytral suture in the north of the region: southern China (Guangdong, EW maximum width between outer margins of elytra Gansu, Sichuan), Taiwan, Nepal, northern Thailand and PEL length between anterior angles of pronotum and apices of elytra Vietnam. One unidentifi ed species is known from Java PPW width between posterior angles of pronotum. (Indonesia). The exact distribution of G. semimarginatus Labels of type specimens were recorded verbatim in is unknown (its holotype was either collected in northern single quotations; a vertical bar | separates rows within a India or southern China, see below). label and a double vertical bar || separates individual labels. Additional remarks are given in square brackets. Key to species Specimens examined in this study are deposited in the following collections: 1(2) Marginal pronotal stria present only on basal pronotal half (Fig. 59). Distribution: China? India? CTLA Tomáš Lackner private collection (temporarily housed in ZSM); ...................... G. semimarginatus Bickhardt, 1920 MFNB Museum für Naturkunde, Berlin, Germany (B. Jäger); 2(1) Marginal pronotal stria complete or nearly complete NHM The Natural History Museum, London, United Kingdom (M. (Fig. 58). Barclay); 3(4) Sutural elytral stria widely interrupted, present OKZC Ondřej Konvička private collection, Zlín, Czech Republic; as short basal fragment and longer fragment on SMNS Staatliches Museum für Naturkunde, Stuttgart, Germany (A. Faille); elytral apical half (Fig. 57). Distribution: Vietnam, ZSM Zoologische Staatssammlung, München, Germany (M. Balke). Thailand. ..... G. vietnamicus Kryzhanovskij, 1972 4(3) Sutural elytral stria present mostly only as short Taxonomy basal fragment, absent from apical elytral half (Fig. 1). Genus Gnathoncus Jacquelin du Val, 1857 5(6) Elytral disc (except for a part of third elytral interval Gnathoncus: M (2011): 175 (catalogue); V R (2013): and space between fourth dorsal elytral and sutural 30 (description of a new species from Iran); L et al. (2015): striae) with very dense alutaceous microsculpture 113 (catalogue); L L (2017): 28 (diagnosis and key to the Australopacifi c Gnathoncus). (Fig. 4), giving the species ‘matte’ appearance. Distribution: China: Sichuan. ................................. Note. Complete list of synonymies and literature refe- ............................................ G. sechuanus sp. nov. rences of this taxon are given in L (2010: 105) 6(5) Elytral disc without dense alutaceous microsculpture and the reader is referred to them there. For the sake of among punctures, rather shiny (Fig. 1). completeness we only list the references published after 7(8) Punctures of pygidium round (Fig. 52), legs dark- L (2010) above. brown (Fig. 2). Distr.: Almost entire Palaearctic Diagnosis. Members of the genus Gnathoncus can be Region, in SE Asia recorded from China: easily distinguished from all other SE Asian Saprininae Guangdong. ........ G. nannetensis (Marseul, 1862) by the following external and genitalic characters: body 8(7) Punctures of pygidium oval-shaped (Fig. 53), legs rather small (PEL=1.70–3.20 mm), uniformly