Manfred A. Jäch

Two new species of the riffle beetle genus Zaitzevia Champion, 1923 are described from Fujian Province, southeastern China: Z. longyanensis sp. nov . and Z. yanfengi sp. nov . The genus Zaitzevia is here recorded from Fujian for the first time. Photographs of diagnostic characters are provided.

This is the first annotated checklist of the Hydraenidae of Croatia. It is based on reliable literature data and the examination of unpublished specimens identified by the authors. A total of 65 species is confirmed to occur in Croatia: 26 species of Hydraena Kugelann, 1794, nine species of Limnebius Leach, 1825, and 30 species of Ochthebius Leach, 1815. With regard to the biogeographical regions of Croatia, 47 of these species are found in the Mediterranean Region, 28 in the Continental and 14 in the Alpine Region. Four species are recorded from Croatia for the first time: Hydraena (s. str.) assimilis Rey, 1885, Limnebius (s. str.) aluta Bedel, 1881, Ochthebius ( Asiobates ) flavipes Dalla Torre, 1877, and O. (s. str.) pedicularius Kuwert, 1887. Four species are classified as “unconfirmed or doubtfully recorded” from Croatia. Ochthebius ( Asiobates ) bicolon Germar, 1824 is deleted from the Croatian checklist. An additional 29 species that potentially could occur in this country are discussed. Only one hydraenid species, Hydraena angustata Sturm, 1938, is currently regarded as endemic to Croatia, but it is assumed to be more wide-spread. A total of 14 Croatian hydraenid species is regarded as endemic or subendemic to the Balkan Region. Lectotypes are designated for Hydraena (s. str.) croatica Kuwert, 1888 and Ochthebius ( Aulacochthebius ) narentinus Reitter, 1885. A photograph of the dorsal habitus of H . (s. str.) croatica is published for the first time. The history of the exploration of the Hydraenidae of Croatia is outlined. Compared to other South European countries like Spain or Italy, the knowledge of the hydraenid fauna of Croatia is still remarkably poor, and very few Croatian hydraenid specimens have been barcoded so far; only one specimen was found databased in BOLD and GeneBank (accessed June 2025).

A synopsis of the species of the genus Zaitzevia Champion, 1923 from Shaanxi Province (China) is provided. Five new species are described: Z. coronifer sp. nov. , Z. disparilis sp. nov. , Z. hybrida sp. nov. , Z. pilosa sp. nov. , and Z. robusta sp. nov. These five new species are not confined to Shaanxi but recorded also from other provinces: Z. coronifer (Hubei), Z. disparilis (Anhui, Gansu, Guizhou, Hunan), Z. hybrida (Gansu, Sichuan, Yunnan), Z. pilosa (Hubei, Hunan), and Z. robusta (Hubei, Sichuan). A key to the six Zaitzevia species currently known from Shaanxi, as well as photographs of the habitus and the aedeagi, are provided. The morphological delimitation of the genera Zaitzevia and Zaitzeviaria Nomura, 1959 is briefly discussed on the basis of the newly established Zaitzevia hybrida species group, which is wide-spread in the Himalaya and China and combines diagnostic characters of Zaitzevia as well as Zaitzeviaria . In addition, an updated checklist of the 21 species of Zaitzevia now recorded from China is presented. The genus Zaitzevia is recorded for the first time from Anhui, Gansu, and Guizhou. Zaitzevia fengtongzhaiensis Jiang & Chen, 2023 is recorded for the first time from Gansu and Yunnan. Based on particular morphological characters, the specimens recorded by Bian and Zhang (2022) from Shaanxi and Yunnan as Z. chenzhitengi are here regarded as a closely related, undescribed species.

The genus Elmomorphus Sharp, 1888 is redescribed based on morphological characters. Elmomorphus bryanti Hinton, 1935, E. montanus (Grouvelle, 1913), E. prosternalis Hinton, 1935, and E. striatellus Delève, 1968 are redescribed based on type material. Elmomorphus nepalensis Satô, 1981 is redescribed based on material collected in the vicinity of the type locality. Eighteen species of Elmomorphus were known so far world-wide, and only five species have been recorded from the study area (India, Nepal, Bhutan, Myanmar, China, Thailand, Laos, Cambodia, and Vietnam). In the present revision, 45 new species are described: E. auratus sp. nov. (China), E. auripilosus sp. nov. (Vietnam), E. bispinosus sp. nov. (China), E. calvus sp. nov. (China, Vietnam), E. catenatus sp. nov. (China), E. comosiclunis sp. nov. (China), E. corpulentus sp. nov. (China), E. cuneatus sp. nov. (Thailand), E. curvipes sp. nov. (China, Vietnam), E. dentipes Kodada, Selnekovič & Jäch sp. nov. (China, Laos, Myanmar, Thailand, Vietnam), E. depressus sp. nov. (China), E. donatus Kodada, Selnekovič & Jäch sp. nov. (China, Vietnam), E. ellipticus sp. nov. (China), E. elmoides sp. nov. (Vietnam), E. fusiformis sp. nov. (China), E. glabriclunis sp. nov. (China), E. globosus sp. nov. (China), E. hamatus sp. nov. (China), E. hongkong sp. nov. (China), E. horaki Kodada, Selnekovič & Jäch sp. nov. (Cambodia, Myanmar, Thailand), E. jendeki Kodada, Selnekovič & Jäch sp. nov. (Vietnam), E. jii sp. nov. (China), E. longitarsis sp. nov. (Thailand), E. mazzoldii sp. nov. (Thailand), E. minutus sp. nov. (China), E. oblongus sp. nov. (Vietnam), E. ovalis Kodada, Selnekovič & Jäch sp. nov. (China), E. parabrevicornis sp. nov. (China), E. paradonatus Kodada, Selnekovič & Jäch sp. nov. (China), E. paramontanus Kodada, Selnekovič & Jäch sp. nov. (China, Laos, Malaysia, Myanmar, Thailand, Vietnam), E. parvulus sp. nov. (Thailand), E. punctulatus sp. nov. (China), E. reticulatus sp. nov. (China), E. sausai Kodada, Selnekovič & Jäch sp. nov. (Vietnam), E. schillhammeri sp. nov. (China), E. schoenmanni sp. nov. (China), E. siamensis Kodada, Selnekovič & Jäch sp. nov. (Cambodia, Laos, Myanmar, Thailand, Vietnam), E. similis sp. nov. (China, Laos, Vietnam), E. simplex sp. nov. (China), E. simplipes sp. nov. (Vietnam), E. superficialis sp. nov. (China), E. sulcatus sp. nov. (China), E. umphangicus Kodada, Selnekovič & Jäch sp. nov. (Thailand), E. vietnamensis sp. nov. (Vietnam), and E. yunnanensis Kodada, Selnekovič & Jäch sp. nov. (China). The genus Elmomorphus is recorded for the first time from Bhutan, Cambodia, Myanmar, and Laos. In China (31 spp. from Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hong Kong, Hubei, Hunan, Jiangxi, Shaanxi, Yunnan, Zhejiang) and Vietnam (16 spp.), this genus is especially diverse.

Molecular data for 19 specimens of Elmis syriaca syriaca and E. s. zoufali from eight countries have been analysed in order to investigate the taxonomic status and the geographical distribution of these two subspecies. The nominative subspecies was previously thought to be endemic to the Levant (Israel, Lebanon, Syria), while E. s. zoufali was regarded as being widespread from the Balkans to eastern Anatolia and Afghanistan. The results of our molecular studies using DNA barcoding and nuclear DNA data reveal that the two taxa are in fact distinct species, which separated around 2 Mya. A distinction based on the external morphological characters of 354 specimens was found to be impossible due to the pronounced variability, especially of the pronotal microsculpture, which had hitherto been used as the main distinguishing feature. The two species can only be distinguished by the aedeagal parameres and by the geographical distribution, which deviates considerably from the concept of previous authors. Elmis zoufali is distributed in Romania, the Balkan Peninsula, some Aegean Islands and in western Anatolia, while E. syriaca occurs from the Caucasus region southwards to eastern Turkey, Iran (probably also Afghanistan) and the Levant. Geographically, both species are widely separated by the so-called Anatolian Diagonal. Elmis zoufali resp. E. syriaca are recorded for the first time from Croatia, Romania, Azerbaijan, Georgia, Iran and Turkey. In addition, we examined 13 specimens tentatively identified as Elmis quadricollis (Reitter, 1887), a closely related species from Central Asia; we sequenced one specimen from China, which was revealed to be a sister to E. zoufali and E. syriaca.

A single elmid larva is reported from a laminate maroon shale bed of Gurha opencast lignite mine (Palana Formation, early Eocene, Bikaner District, north-western Rajasthan, India). It is the first fossil larva that can be attributed to Elmidae with certainty. A generic assignation is not possible, because the larva is strongly compressed, and the most important characters are not visible or poorly preserved. The larva is described morphologically and illustrated by photographs and line drawings. A larva of a holometabolous insect from Baltic amber, which was published recently as a member of Elmidae by Zippel et al. (2022), possesses no structural characters that would clearly suggest placement in this family. A photograph of the hitherto unknown larva of the extant Grouvellinus rioloides from Kyrgyzstan is included for comparison.

A new species of the water scavenger beetle, Regimbartia majorobtusa Mai, Jia, and Jäch sp. n., is described from China (Yunnan) and Thailand (Phitsanulok). It is the eleventh known species of this genus. Regimbartia attenuata (Fabricius, 1801 Fabricius, J.C. (1801), Systema Eleutheratorum … (Vol. 1), Kiliae: Bibliopolii Academici Novi, pp. 24–506. [Google Scholar] ) is redescribed; it is reported for the first time from the Chinese provinces Shaanxi and Hubei. A key to the Chinese species of the genus Regimbartia Zaitzev, 1908 Zaitzev, F.A. (1908), ‘Beitrag zur Kenntnis der Wasserkäfer von Chinesisch-Centralasien’, Annuaire du Musée Zoologique de L’Académie Impériale Des Sciences de St. Pétersbourg, 13, 417–426. [Google Scholar] is provided, and the two remaining Asian species, R. minima Orchymont, 1941 Orchymont, A. (1941), ‘Revision Des Espèces du Genre Régimbartia Zaitzev (Coleoptera Hydrophilidae)’, Bulletin du Musée Royal D’Histoire Naturelle de Belgique, 17, 1–15. [Google Scholar] and R. sumatrensis Orchymont, 1941 Orchymont, A. (1941), ‘Revision Des Espèces du Genre Régimbartia Zaitzev (Coleoptera Hydrophilidae)’, Bulletin du Musée Royal D’Histoire Naturelle de Belgique, 17, 1–15. [Google Scholar] , are diagnosed. http://www.zoobank.org/urn:lsid:zoobank.org:pub:992D271C-3327-4706-8625-7662CA4E2EF4

Hydraena schuleri Ganglbauer, 1901 was rediscovered after 18 years in Starý Potok, a small stream in eastern Slovakia, and we recorded it, for the first time, from the small rivers Stará Rieka and Udava in southern and eastern Slovakia. Adults were collected mainly from submerged moss growing on rocks in shallow water, where they were found together with Hydraena minutissima Stephens, 1929, H. pulchella Germar, 1824, H. pygmaea Waterhouse, 1833; Ochthebius colveranus Ferro, 1979, O. melanescens Dalla Torre, 1877, and O. metallescens Rosenhauer, 1847. We provide illustrations of the habitus and aedeagus, and a distribution map.

With some 3,700 described species, Dryopoidea are a moderately diverse superfamily of beetles whose position within basal Polyphaga has been historically difficult to elucidate. Members of most extant dryopoid families are set apart from the majority of other polyphagans by their association with aquatic habitats, but little is known about the origin of these derived life habits and the phylogeny of the superfamily. Here we describe Mastigocoleidae Tihelka, Jäch, Kundrata & Cai fam. nov., a new family of Mesozoic dryopoids represented by fossils from the Cretaceous Yixian Formation in northeastern China (undescribed species; ~125 Ma), Crato Formation in northeastern Brazil (Mastigocoleus rhinoceros Tihelka & Cai gen. et sp. nov.; ~113 Ma), and amber from northern Myanmar (Mastigocoleus resinicola Tihelka & Cai gen. et sp. nov. and Cretaceocoleus saetosus Tihelka, Kundrata & Cai gen. et sp. nov.; ~99 Ma). Integrating the findings of recent molecular and morphological phylogenetic analyses, we recover Mastigocoleidae as an early-diverging dryopoid clade sister to the families Lutrochidae and Dryopidae, or less likely as a group of putative stem-dryopoids. Mastigocoleidae are most distinctly separated from all other dryopoid families by their whip-like antennae, with 11 antennomeres, reaching to the pronotal base, and with the scape broadest and longest, a short pedicel, and antennomeres II–XI more or less distinctively gradually tapering toward the apex. Mastigocoleidae indicate that the last common ancestor of Dryopoidea was likely terrestrial in the adult stage, and document character acquisitions associated with a specialization for aquatic life.