Historical DNA solves century-old mystery on sessility in freshwater gastropods

Extinction rates are increasing unabatedly but resources available for conservation action are limited. Therefore, some conservationists are pushing for ecology- and evolution-based conservation choices, prioritizing taxa with phylogenetic and trait-based originality. Extinction of original taxa may result in a disproportionate loss of evolutionary innovations and potentially prevent transformative changes in living systems. Here, we generated historical DNA data from an almost 120-year-old syntype of the enigmatic sessile snail Helicostoa sinensis from the Three Gorges region of the Yangtze River (PR China), using a next-generation sequencing protocol developed for ancient DNA. In a broader phylogenetic context, we assessed the phylogenetic and trait-based originality of this enigmatic taxon to solve the century-old puzzle of sessility in freshwater gastropods. Our multi-locus data confirm the phylogenetic and trait-based originality of H. sinensis. It is an ultra-rare, subfamily-level taxon (Helicostoinae stat. nov.) within the family Bithyniidae, which exhibits the evolutionary innovation of sessility. While we conservatively classify H. sinensis as "Critically Endangered", there is mounting evidence of the biological annihilation of this endemic species. Although rapidly rising extinction rates in invertebrates are increasingly recognized, the potential loss of originality in these "little things that run the world" has received little attention. We therefore call for comprehensive surveys of originality in invertebrates, particularly from extreme environments such as rapids of large rivers, as a basis for urgently needed ecology- and evolution-based conservation decisions.

Crenobiont, stygophile and stygobiont molluscs in the hydrographic area of the Trebišnjica River Basin

In the paper the crenobiont, stygophile and stygobiont malacofauna of the karst area of Popovo Polje around Trebinje (Eastern Herzegovina, BiH) is presented. The materials were collected from springs, caves and interstitial habitats (with a Bou-Rouch pump) at 23 localities. The following species were found: Pisidium cf. personatum A.W. Malm, 1855, Theodoxus callosus (Deshayes, 1833), Sadleriana fluminensis (Küster, 1852), Radomaniola curta (Küster, 1852), Radomaniola cf. bosniaca (Radoman, 1973), Kerkia briani Rysiewska & Osikowski, 2020, Montenegrospeum bogici (Pešić & Glöer, 2012), Litthabitella chilodia (Westerlund, 1886), Travunijana vruljakensis Grego & Glöer, 2019, a new genus and species of the Sadlerianinae, Emmericia ventricosa Brusina, 1870, Iglica cf. absoloni (A.J. Wagner, 1914), Plagigeyeria tribunicae Schütt, 1963, Paladilhiopsis arion Rysiewska & Osikowski, 2021, Valvata montenegrina Glöer & Pešić, 2008, Radix labiata (Rossmässler, 1835), Galba truncatula (O. F. Müller, 1774), Ancylus recurvus Martens, 1783, Ancylus sp. and the amphibiotic Succinea cf. putris (Linnaeus, 1758). The redescription of the genus Travunijana Grego & Glöer, 2019, applying the characteristics of shell, female reproductive organs and penis, is also presented. The new genus and species are described, based on the shell, penis, radula and fragmentary data on the female reproductive organs. For all species, the mitochondrial cytochrome oxidase subunit I (COI) is applied to confirm the determination; in the case of Travunijana and the new genus, the nuclear histone H3 locus is also used, in order to infer both their distinctiveness and phylogenetic relationships.

A new species of Kerkia Radoman, 1978 (Caenogastropoda, Hydrobiidae) from Bosnia and Herzegovina

A new species of Kerkia, K.briani Rysiewska & Osikowski, sp. nov. is described from the spring Polički Studenac Vrelo (Crkvina), adjacent to the Trebišnjica River (Bosnia and Herzegovina) collected with Bou-Rouch technique, pumped from an interstitial habitat 50 cm below the bottom of the spring. The shell, female reproductive organs, and the penis are described and illustrated. Mitochondrial cytochrome oxidase subunit I (COI) and nuclear histone H3 partial sequences confirm the distinctness of the new species, and molecularly based phylogenetic relationships of Kerkia are briefly presented.

Revealing the stygobiotic and crenobiotic molluscan biodiversity hotspot in Caucasus: Part I. The phylogeny of stygobiotic Sadlerianinae Szarowska, 2006 (Mollusca, Gastropoda, Hydrobiidae) from Georgia with descriptions of five new genera and twenty-one new species

The position of the southwestern Caucasus as a stygobiotic Mollusca hotspot is confirmed. Molecular data of stygobiotic gastropods revealed the diversity of subfamily Sadlerianinae Szarowska, 2006, inhabiting the subterranean environment of Georgia. In addition to the well-known endemic genera Pontohoratia Vinarski, Palatov & Glöer, 2014 and Motsametia Vinarski, Palatov & Glöer, 2014, five more genera were identified in northwestern Georgia as new to the science: Kartvelobia gen. nov., Imeretiopsis gen. nov., Caucasopsis gen. nov., Caucasogeyeria gen. nov., and Hausdorfenia gen. nov. Additionally, 21 new species were found to inhabit the studied area (Samegrelo, Imereti, Racha regions in Georgia).