Arganiella Giusti & Pezzoli, 1980 (Caenogastropoda: Truncatelloidea: Hydrobiidae): a widespread genus or several narrow-range endemic genera? Author Delicado, Diana ED8CD4C8-7310-40E3-8821-7721615A5992 Justus Liebig University Giessen, Department of Animal Ecology & Systematics, Heinrich-Buff-Ring 26 - 32 IFZD, 35392 Giessen, Germany. didelicado@gmail.com Author Pešić, Vladimir 2B46F869-1202-47A9-9359-0BE04D691F6C University of Montenegro, Faculty of Sciences, Department of Biology, Cetinjski put b. b., 81000 Podgorica, Montenegro. vladopesic@gmail.com Author Ramos, Marian A. C108BACD-06A7-4C6D-8466-2A1CFE349DEB Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutiérrez Abascal 2, 28006 Madrid, Spain. m.ramos@mncn.csic.es text European Journal of Taxonomy 2021 2021-05-21 750 1 140 155 http://dx.doi.org/10.5852/ejt.2021.750.1369 journal article 4362 10.5852/ejt.2021.750.1369 cd2883dd-811d-4617-a315-68c78d7e4490 2118-9773 5451701 FFDAD9F7-5E6A-40DA-9D2F-1713CE7AFF4A Genus Aretiana Delicado & Ramos gen. nov. urn:lsid:zoobank.org:act: 7B207B6D-47E8-4211-8139-0CF98DA353D7 Type species Boetersiella wolfi Boeters & Glöer, 2007 . Fig. 1. Maximum likelihood tree based on the combined (COI, 18S) dataset. Statistical support of the nodes is indicated when Bayesian posterior probabilities ≥ 0.95 and bootstrap supports ≥ 75% (black dots). On the right, the morphology of shell, penis and distal female genitalia is presented for: a) Arganiella wolfi Boeters & Glöer , b) A. pescei Giusti & Pezzoli, 1980 and c) A. tabanensis Boeters, Glöer & Pešić, 2014 . Reproductive organs were re-drawn from Arconada & Ramos (2007a) , Bodon et al. (2001) and Boeters et al. (2014) for the three species, respectively. Scale bar below topology: substitutions per site. Revised diagnosis Shell trochiform; whorls 3.5–4.0; aperture complete, rounded; outer lip narrow, straight in lateral profile; umbilicus wide. Operculum corneous, yellowish, thin, pliable, oval to rounded, paucispiral with a central nucleus, without peg. Two pairs of basal cusps on each central radular tooth. Ctenidium well developed, with approximately 14 gill filaments. Osphradium positioned opposite to approximately the middle of the ctenidium. Stomach without gastric caecum; rectum forms a gentle U-shape in the mantle cavity. Bursa copulatrix medium-sized, pyriform, pedunculated and protruding beyond the posterior edge of the albumen gland; bursal duct shorter than bursal length; unpigmented renal oviduct that makes a complete loop over the pallial gland; one elongated or pyriform seminal receptacle arising from the renal oviduct, just above the insertion point with the bursal duct. Prostate gland bean-shaped, about twice as long as wide. Penis small and simple, gradually tapering. Nervous system unpigmented. Etymology The genus is named after Villa Aretiana , the Roman name of the town Aracena, which gives its name to the mountain range where the genus was found (i.e., Sierra de Aracena); gender feminine. Remarks Aretiana Delicado & Ramos gen. nov. can be distinguished from Arganiella as the former has a taller shell, a more oval operculum, pigmentation on the body and eyespots, fewer gill filaments, a narrower penis, a larger and pyriform bursa copulatrix located beyond the posterior edge of the albumen gland and fewer cusps on the lateral radular teeth (for comparison, see Giusti & Pezzoli 1980 ; Boeters & Glöer 2007 ; Arconada & Ramos 2007a ). The new genus differs from the closely related genus Iberhoratia by its taller shell with a narrower umbilicus, the absence of lobes on the inner edge of the penis and of a proximal seminal receptacle (SR2) and presence of two pairs of basal cusps on each central radular tooth (see Arconada et al. 2007). Mean COI divergence for Aretiana Delicado & Ramos gen. nov. was 15.9% with Arganiella and 11.2% with Iberhoratia .