A review of the Malthinus flaveolus (Herbst, 1786) group of species (Coleoptera: Cantharidae) of the European part of Russia and the Caucasus

Том 21. Вып. 2 Vol. 21. Iss. 2 CAUCASIAN ENTOMOLOGICAL BULLETIN Ростов-на-Дону 2025 РОССИЙСКАЯ АКАДЕМИЯ НАУК Южный научный центр RUSSIAN ACADEMY OF SCIENCES Southern Scientific Centre Кавказский энтомологический бюллетень 21(2): 307–311 Caucasian Entomological Bulletin 2025 A review of the Malthinus flaveolus (Herbst, 1786) group of species (Coleoptera: Cantharidae) of the European part of Russia and the Caucasus © S.V. Kazantsev Diplomatic Academy of the Ministry of Foreign Affairs of the Russian Federation, Ostozhenka Street, 53/2, Moscow 119021 Russia. E-mail: kaz[email protected] Abstract. The list of soldier beetles of the genus Malthinus Latreille, 1805 of the Caucasus is complemented with Malthinus pseudoflaveolus Wittmer, 1974 from the M.flaveolus (Herbst, 1786) species group. Although M.pseudoflaveolus had been reported from the region, it was later excluded from the Caucasian fauna. This time it is registered in Georgia, and this increases the total number of Malthinus species known from the Caucasus to15. The habitus of M.pseudoflaveolus, as well as the aedeagi and male ultimate abdominal segments of M.flaveolus, M.pseudoflaveolus and M.flaveoloides Švihla, 1997 are illustrated. Key words: Cantharidae, Malthininae, Malthinus, faunistics, Caucasus, Palaearctic region. Обзор группы видов Malthinus flaveolus (Herbst, 1786) (Coleoptera: Cantharidae) европейской части России и Кавказа © С.В. Казанцев Дипломатическая академия МИД России, ул. Остоженка, 53/2, Москва 119021 Россия. E-mail: kaz[email protected] Резюме. Список мягкотелок рода Malthinus Latreille, 1805 Кавказа дополняется Malthinus pseudoflaveolus Wittmer, 1974 из группы видов M.flaveolus (Herbst, 1786). Хотя M.pseudoflaveolus ранее указывался из региона, позднее он был исключен из кавказской фауны. На этот раз он обнаружен в Грузии, что увеличивает общее число зарегистрированных на Кавказе видов Malthinus до15. Приведены фотографии габитуса M.pseudoflaveolus, а также эдеагусов и вершинных сегментов брюшка самцов M.flaveolus, M.pseudoflaveolus и M.flaveoloides Švihla, 1997. Ключевые слова: Cantharidae, Malthininae, Malthinus, фаунистика, Кавказ, Палеарктика. Introduction Malthinus flaveolus (Herbst, 1786) is the type species of the soldier beetle genus Malthinus Latreille, 1805, the type genus of the subfamily Malthininae. The genus accounts for over 350species distributed throughout the Holarctic realm, also penetrating into the Neotropics and the Oriental region [Delkeskamp, 1977; Kazantsev, Brancucci, 2007]. The Caucasian fauna lists 14species of this genus [Švihla, 1990, 1997; Wittmer, 1992; Kazantsev, 2001, 2024, 2025a,b]. Malthinus is divided into two subgenera, Malthinuss. str., with the maximum distribution range, and Indomalthinus Brancucci, 1978, restricted to Nepal, Himalayan and sub-Himalayan provinces of India and Pakistan, and central China [Brancucci, 1980; Kopetz, 2015; Kazantsev, 2025c]. At the same time, there appear to be easily recognisable species groups in the nominotypical subgenus, the Caucasian representatives of two of which, M.facialis Thomson, 1864 and M.biguttatus (Linnaeus, 1758) groups, were reviewed recently [Kazantsev, 2025a,b]. The Malthinus flaveolus group is another well-defined group of species in Malthinuss.str., including four species: the pan-European M.flaveolus (Herbst, 1786), M.deceptor Baudi di Selve, 1893 from Italy, M.pseudoflaveolus Wittmer, 1974 from Turkey and M. flaveoloides Švihla, 1997 from the Caucasus [Švihla, 1997]. The group is characterized by the widened anteriorly and more or less rounded at anterior margin pronotum, absent of elytral longitudinal rows of punctures, mostly light yellow (except head and elytra) body and by the specific structure of the aedeagus, with very long median piece, developed parameres, lateroand interophyses (Figs1–3,9–13). An opportunity to study the new Malthinus material collected during the 2024–2025 expeditions to Georgia allows adding another species, M. pseudoflaveolus, to the fauna of the country and of the Caucasus in general. Although it had been reported for the Caucasus by Wittmer [1992], later it was excluded from the regional fauna after the Caucasian ‘M. pseudoflaveolus’ specimens from the Wittmer collection in the Naturhistorisches Museum in Basel were re-examined by Švihla [1997], who found them to represent a new species, M.flaveoloides. Thus, although the species was mentioned in the catalogue of Palaearctic Coleoptera as occurring in Georgia and the northwestern Caucasus in Russia [Kazantsev, Brancucci, 2007], it was excluded from the fauna of these territories in a later Identification Key to soldier beetles [Kazantsev, 2022]. Now, with the material from the Meskheti Mountains (southern Georgia) and Upper Svaneti (northwestern Georgia) at hand, it is obvious that M. pseudoflaveolus does occur in the Caucasus. The aedeagi and male ultimate abdominal segments of the three species of the Malthinus flaveolus group of the region are illustrated below. DOI: https://doi.org/10.5281/zenodo.17897443 Research Article / Научная статья Material and methods The studied beetles were glued on cardboard plates or triangles. Before the examination, they were relaxed in water, then their detached abdomens were kept for several hours in 10% KOH at room temperature. The KOH treated aedeagi and terminal abdominal segments were then placed in microvials with glycerin for photographing. MSP-1 zoom stereoscopic dissecting microscope with 8–80times magnification range was used for examination of diagnostic characters. Photographs were taken with a Canon EOS 6D camera and Canon MP-E 65mmlens and processed with Zerene Stacker and Adobe Photoshop software. The following acronym is used the text: ICM – Insect Center (Moscow, Russia); ZMMU – Zoological Museum of Moscow University (Moscow, Russia). Figs 1–13. Malthinus (s. str.), males. 1, 4–5, 9 – M. flaveolus; 2, 6–7, 10–11 – M. pseudoflaveolus; 3, 8, 12–13 – M. flaveoloides. 1–3 – general view (1, 3 – after Kazantsev [2022]); 4–8 – ultimate abdominal segments: 4, 6, 8 – ventrally, 5, 7 – laterally; 9–13 – aedeagi: 9, 10, 12 – ventrally, 11, 13 – laterally. Scale bars 0.5 mm. Рис. 1–13. Malthinus (s. str.), самцы. 1, 4–5, 9 – M. flaveolus; 2, 6–7, 10–11 – M. pseudoflaveolus; 3, 8, 12–13 – M. flaveoloides. 1–3 – общий вид (1, 3 – по [Kazantsev, 2022]); 4–8 – вершинные брюшные сегменты: 4, 6, 8 – снизу, 5, 7 – сбоку; 9–13 – эдеагусы: 9, 10, 12 – снизу, 11, 13 – сбоку. Масштабные линейки 0.5 мм. 308 S.V. Kazantsev Family Cantharidae Imhoff, 1856 (1815) Subfamily Malthininae Kiesenwetter, 1852 Tribe Malthininae Kiesenwetter, 1852 Genus Malthinus Latreille, 1805 Subgenus Malthinus Latreille, 1805 Malthinus Latreille, 1805: 261 (type species Cantharis flaveola Herbst, 1786 (subsequent designation by Delkeskamp [1977])). = Apteromalthinus Escalera, 1913: 322 (type species Apteromalthinus pithanoides Escalera, 1913 (by monotypy)). = Malachidius Motschulsky, 1860: 62 (type species Malthinus conspicuus Kiesenwetter, 1852 (original designation)). = Progeutes Abeille de Perrin, 1894: 92 (type species Malthinus longipennis P.H.Lucas, 1846 (subsequent designation by Delkeskamp [1977])). = Ymnis Des Gozis, 1886: 23 (type species Malthinus flaveolus Herbst, 1786 (original designation)). Malthinus (s. str.) flaveolus (Herbst, 1786) (Figs 1, 4, 5, 9) Cantharis flaveolus Herbst, 1786: 171. = Cantharis collaris Latreille, 1805: 262. = Cantharis flavus Latreille, 1805: 262. = Malthinus griseipennis Pic, 1913: 97. = Cantharis immunis Marsham, 1802: 374. = Telephorus minimus A.G. Olivier, 1790: no.26, 17. = Malthinus robustus Motschulsky, 1853: 4. = Malthinus subfusca Pic, 1906: 24. Material. 1♂ (ICM), “E Moscow, Bykovo, VNIIKR, 4.VI.2012, S. Kurbatov leg.”; 1♂ (ICM), “Russia, Crimea, Bakhchis., Sokolinoe, 44°32ʹ08.6ʺN 33°58ʹ29.0ʺE, 300m, 27.V.2022, A.Prosvirovleg.”. Notes. Malthinus flaveolus differs from M.pseudoflaveolus and M.flaveoloides in the shape of the ultimate male abdominal ventrite, with not medially incised, in ventral view, apex, and abruptly bent in the middle, in lateral view, ultimate abdominal tergite (Figs4,5). Distribution. Malthinus (s. str.) flaveolus is distributed in the forest zone from Western Europe to West Siberia [Kazantsev, Brancucci, 2007; Sergeeva et al., 2024]. Malthinus (s. str.) pseudoflaveolus Wittmer, 1974 (Figs 2, 6, 7, 10, 11) Malthinus pseudoflaveolus Wittmer, 1974: 422. Material. Russia. 3♂ (ICM), “Caucasus, Dagestan, Gunib, ca.1500m, 25.VI.89, S.Kazantsevleg.”, “Malthinus pseudoflaveolus Wittm., det.W.Wittmer” (Wittmer’s manuscript label). Georgia. 2♂, 6♀ (ICM), “Georgia, env. Bakuriani, 2–3 km ESE Patara Mitarbi, 1500–1770 m, 41.77°N 43.59°E, 19.VII.2024, S. Kazantsev leg.”; 2♂ (ICM), “Gruzia: UPPER SVANETI, N Nakra, 1300–1600 m, 43.103°N 42.394°E, 11.VII.2025, S. Kazantsev leg.”; 2♂ (ICM), “Gruzia: UPPER SVANETI, E Nakra, 1400–1800 m, 43.086°N 42.365°E, 12.VII.2025, S. Kazantsevleg.”; 1♂, 1♀ (ICM), “Gruzia: UPPER SVANETI, SMestia, env.Heshkili, 1800–1850m, 43.016°N 42.710°E, 13–14. VII.2025, S. Kazantsev leg.”; 9♂, 7♀ (ICM), “Gruzia: UPPER SVANETI, SMestia, 1.5km E Heshkili, 1800m, 43.017°N 42.697°E, 17–19.VII.2025, S. Kazantsev leg.”; 9♂, 7♀ (ICM), 1♂, 1♀ (ZMMU), “Gruzia: UPPER SVANETI, SMestia, 1.5km E Heshkili, 43.017°N 42.697°E, 1800m, 17–19. VII.2025, S.Kazantsevleg.”. Notes. In the description M.pseudoflaveolus is separated from M.flaveolus by the shape of last abdominal sternites and the aedeagus – however, the author of the taxon does not say how exactly the sternites are different and does not describe or illustrate them [Wittmer, 1974]. Asit is seen in the photographs, in M.pseudoflaveolus the ultimate male abdominal ventrite, in ventral view, is indeed, unlike in M.flaveolus, noticeably incised at apex (Figs6,7). Distribution. Malthinus (s. str.) pseudoflaveolus is known from Turkey (“Artwin”, type locality), Georgia (Upper Svaneti and Meskheti Mountains) and the Eastern Caucasus in Russia (Dagestan). Malthinus (s. str.) flaveoloides Švihla, 1997 (Figs 3, 8, 12, 13) Malthinus flaveoloides Švihla, 1997: 123. Material. 1♂ (ICM), “Abkhasia, Tsumuri, h=420m, 28.V.1980”; 3♂, “Abkhasia, Ritsa RelicN.P., NNW AwadkharaStn, subalpine, 1700–1800m, 43.541°N 40.637°E, 4.VII.2021, S. Kazantsev leg.”; 2♂, 2♀ (ICM), 1♂, 1♀ (ZMMU), “Abkhasia, Ritsa Relic N.P., Ritsa Lake shore, 950–1000 m, 43.486°N 40.548°E, 6.VII.2021, S.Kazantsevleg.”; 2♂, 2♀ (ICM), “Abkhasia, Ritsa Relic N.P., N Gega Waterfalls, 550–750 m, 43.443°N 40.447°E, 11.VII.2021, S. Kazantsev leg.”; 1♂ (ICM), “Abkhasia, Ritsa Relic N.P., BzybV./Kuzhba-Yashta road, 600–900 m, 43.393°N 40.522°E, 11.VII.2021, S.Kazantsevleg.”. Notes. The type locality of Malthinus flaveoloides is “Mcara” near Gudauta in Abkhazia [Švihla, 1997], and all studied specimens from Abkhazia and the Northwestern Caucasus, in addition to the aedeagal structures mentioned in the description were found to differ from both M.flaveolus and M.pseudoflaveolus in the noticeably more prominent incision at the apex of ultimate male abdominal ventrite (Fig.8). Distribution. Malthinus (s. str.) flaveoloides has been reported from Russia (Northwestern Caucasus), Abkhazia, Georgia and Turkey [Švihla, 1997], although its occurrence in Turkey [Švihla, 1997: “Macka”] and Georgia [Švihla, 1997: “Georgia”] needs confirmation, as it may be based on material from Abkhazia (in case of Georgian attribution), or on misidentification of M.pseudoflaveolus specimens. The three studied species of the M. flaveolus group are hardly distinguishable externally (Figs1–3) and do not seem to differ much in female external genitalia. At the same time the males of the three species may be rather easily separated by the shape of the ultimate abdominal ventrite and the details of the aedeagus (Figs4–13). Akey to the males of these species is presented below. A key to males of the Malthinus flaveolus (Herbst, 1786) species group of the European part of Russia and the Caucasus 1(2). Ultimate abdominal ventrite, in ventral view, not medially incised; ultimate tergite: in lateral view, abruptly bent in the middle; ventral plate of aedeagus with inconspicuous lobes; laterophyses, in ventral view, lyriform, laterally sinuate (Figs4,9) .................... .............................................................. M. (s. str.) flaveolus 2(1). Ultimate abdominal ventrite, in ventral view, medially incised; ultimate tergite: in lateral view, not abruptly bent in the middle; ventral plate of aedeagus with prominent lobes; laterophyses, in ventral view almost straight (Figs5–8,11–13). 3(4). Ultimate abdominal ventrite, in ventral view, with short median incision, ca5times shorter than length of the ventrite; ventral plate of aedeagus with relatively narrow lobes (Figs5,6, 11,12) .......................................... .................................................. M. (s. str.) pseudoflaveolus A review of the Malthinus flaveolus (Herbst, 1786) group of species 309 Fig. 14. Distribution of the Malthinus flaveolus species group in the Caucasus: white squares – M. pseudoflaveolus, black squares – M.flaveoloides. Рис. 14. Распространение группы видов Malthinus flaveolus на Кавказе: белые квадраты – M. pseudoflaveolus, черные квадраты – M.flaveoloides. 4(3). Ultimate abdominal ventrite, in ventral view, with relatively long median incision, only ca 3.3 times shorter than length of the ventrite; ventral plate of aedeagus with relatively wide lobes (Figs7,8,13) ..... ......................................................... M. (s. str.) flaveoloides Discussion The distribution pattern of the two species of M. flaveolus species group in the Caucasus is such that M.pseudoflaveolus is registered in western and southern Georgia and in Dagestan (Russia), while M.flaveoloides is presumably restricted to the Northwestern Caucasus and Abkhazia (Fig.14). Thus, in the extreme west of the Caucasus there is only one species of the group, M.flaveoloides, which occurs both on the northern (Northwestern Caucasus) and southern (Northwestern Caucasus and Abkhazia) macroslopes of the Great Caucasian range. Inthe central Great Caucasus there is one species, M.pseudoflaveolus, found on the southern macroslope of the mountain range. In the east, there is again just one species, the same M. pseudoflaveolus, which occurs on the northern macroslope, in Dagestan. Finally, M. pseudoflaveolus is also found on the Meskheti range in the Smaller Caucasus, in southern Georgia and Turkish Artvin Province. The occurrence and distribution pattern of species of this group in Armenia, eastern Georgia and Azerbaijan, i.e., in the central and eastern Caucasus and Transcaucasia, as well as the occurrence of M.pseudoflaveolus in Turkish Maçka, still need to be verified/defined. In terms of altitude distribution, M. flaveoloides appears to be more flexible: it was collected (judging by the labels with available relevant data) from 420 to 1800ma.s.l., while M.pseudoflaveolus– only from 1300 to 1800ma.s.l. Acknowledgements It is my pleasant duty to express gratitude to DrV.Yu.Savitsky (ZMMU) for the opportunity to study the Cantharidae collection under his supervision. References Abeille de Perrin E. 1894. Diagnoses de Coléoptères réputés nouveaux. L’Echange. 10: 91–94. Brancucci M. 1980. Morphologie comparée, évolution et systématique des Cantharidae (Insecta: Coleoptera). Entomologica Basiliensia. 5: 215–388. Delkeskamp K. 1977. Coleopterorum Catalogus Supplementa. 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A review of the Malthinus flaveolus (Herbst, 1786) group of species 311 Received / Поступила: 24.08.2025 Accepted / Принята: 7.10.2025 Published online / Опубликована онлайн: 12.12.2025