Two new stygobiotic species of Horatia Bourguignat, 1887 (Hydrobiidae) from Croatia

Andrzej Falniowski,Aleksandra Rysiewska,Artur Osikowski,Jozef Grego,Sebastian Hofman

doi:10.3897/subtbiol.37.61573

Abstract

In this paper we describe two new species of the freshwater snails of genus Horatia. A new stygobiotic species of Horatia Bourguignat, 1887 is described from Izvor Beguša in Croatia. It occurs in sympatry with the crenobiotic H. klecakiana Bourguignat, 1887, but is morphologically and molecularly distinct. It is characterized by the terminal part of the body whorl separated from the columella, and neither eyes nor any pigment on the soft parts. It is a stygobiont gastropod, known so far only from one living specimen and several empty shells, thus its soft part morphology and anatomy remain unknown. Another new species of stygobiotic Horatia was found inside the cave Mali Rumin, its description is based solely on numerous empty shells from the cave sediments.

Highlights

Bourguignat (1887) described the genus Horatia, with its type species H. klecakiana Bourguignat, 1887, from “sorgente près de Ribaric, dans la vallée de Cetina” in Croatia (Fig. 1A). Radoman (1983) identified this type locality with the Vrijovac spring in the source area of the Cetina River
The Bourguignat’s syntype is figured at the Fig. 1A, together with seven nominal species from upper Cetina Basin described by him in 1887. All these species (Fig. 1) were later synonymized by Brusina (1907) with H. klecakiana (Radoman 1965, 1966, 1973, 1983), as Bourguignat obviously underestimated the high variability of the species (Glöer and Reuselaars 2020)
The umbilicus presented in the photographs in Szarowska and Falniowski (2014) is exactly identical with the one presented by Glöer and Reuselaars (2020) for their new species H. podvisensis Glöer et Reuselaars, 2020, and with the one of a syntype of H. klecakiana (Fig. 1A)

Summary

Introduction

Bourguignat (1887) described the genus Horatia, with its type species H. klecakiana Bourguignat, 1887, from “sorgente près de Ribaric, dans la vallée de Cetina” in Croatia (Fig. 1A). Radoman (1983) identified this type locality with the Vrijovac spring in the source area of the Cetina River. In 2020 we collected one live specimen (Figs 3, 4A) and several empty shells of Horatia in Izvor Ruda Beguša, cave just above the spring zone and in the spring lake, sieved from sandy sediment at the spring and cave bottom, 13 km ESE of Sinj, Split District, Croatia. It occurred in sympatry with a few living specimens of H. klecakiana. Another stygobiotic species, represented by numerous empty shells and shell fragments was found inside the cave Mali Rumin, Split District, Croatia (in summer 2020), and earlier in the active spring sediments in the same locality (in spring 2017)

Material and methods

Discussion