Two new valvatoid genera (Gastropoda, Hydrobiidae) from Morocco

Recent field surveys conducted on the Middle Atlas of Morocco have led to the discovery of two new species belonging to two new genera ( Ifrania n. gen. and Fessia n. gen.) described here. Photos of the holotypes are presented in addition to the penis morphology of the new genera, the map of the sampling area with the type localities and the habitat description. Ongoing investigations will possibly reveal more new genera and species from the country.


Introduction
Moroccan Hydrobiidae fauna is not well studied and research on hydrobiids in Morocco is still in its infancy.
The shells of Islamia and Arganiella are wide umbilicated, Boetersiella is not. In addition Arganiella is an unpigmented subterranean species which lacks eye-spots (Boeters et al. 2014).
This paper is intended to describe two new valvatoid genera which are different from other genera of the region.

Sampling
Field surveys were conducted from November 2019 (ongoing), in which different localities were prospected along the Middle Atlas hydrosystems. Our goal was to document maximum macroinvertebrate biodiversity in the different microhabitats prospected at each sampling site. The samples of benthic fauna (including mollusks) were collected by a kick net, hand or with a tweezers. The samples have been fixed in 75% ethanol.
The dissections and measurements of the genital organs and the shells were carried out using a stereo microscope (ZEISS); the photographs were made with a digital camera system (Leica R8). The type material is stored in the Zoological Museum of Hamburg (ZMH).

Study Area
The Middle Atlas ( Figure 1) is a mountain range stretched over 350 km, from southwest to northeast of Morocco, located between the Rif and the High Atlas, and covering a total area of 2.3 million hectares, or 18% of the altimontain domain of Morocco, it is among the best watered mountain chains in Morocco and is of great hydrogeological interest. Indeed, of all the Moroccan mountains, the Middle Atlas is the most important water reservoir of the country and it reveals a great diversity of habitats of wetlands, ranging from natural and artificial lakes, to cold rivers and springs (Chillasse & Dakki 2004). The Middle Atlas occupies a privileged place among the Moroccan regions of major interest for the conservation of the wetlands biodiversity, knowing that it host more than a quarter of the country's endemic aquatic fauna (Dakki 1997). However, most of these wetlands are suffering from several anthropic disturbances, which are amplified by repetitive droughts and global changing, as it is the case for all the Moroccan territory and North Africa (Mabrouki et al. 2017(Mabrouki et al. , 2019Taybi et al. 2020).

Description:
The tiny shell is valvatoid with a wide umbilicus. The cylindric penis is very long and thin with a pointed penis tip. The basis is broadened.
Differential Diagnosis: From Islamia the species can be distinguished by the penis, which is in Islamia bilobed.
Etymology: named after the province of Ifran where the species has been collected. Habitat: Zerrouka is a rheocenous natural spring, partially modified, located at Ifran province at an altitude of 1613 m above sea level. The grain size of the bottom consists of stones, pebbles sand and sometimes silt and plant debris. The spring water feeds the Zerrouka lake, a small artificial fish pond classified as a site of biological and ecological interest (SIBE). It is located on the Zerrouka River, the main tributary of the Tizguite wadi. The dam is located about 300m from the source, so that the water from the spring flows directly in it. The reservoir is limited by a concrete wall, at least on the west bank. The aquatic and riparian vegetation at lake level is quite varied. The spring waters are used to supply the town of Ifrane with drinking water. The banks are subjected to a strong anthropic pressure, mainly by trampling cattle.

Description
Shell: The valavatoid shell has a very small spire. The body whorls is very prominent and the last whorl is descended. The first whorls are slightly convex with a clear suture. The aperture is nearly circular and the umbilicus is wide not covered by the last whorl. The outer line of the aperture is straight from lateral view. The peristome is sharp. The shell is 1.1 mm high and 1.5 mm in diameter.
Penis: The cylindric penis is long and slender, widened at the basis and tapered at the distal end with a pointed penis tip.
Operculum: The circular to ovate operculum is slightly concave, yellowish with an orange nucleus, and flat at the nucleus.
Distribution: Morocco, only known from the type locality. Associated species: Physa acuta, Gyraulus sp.

Description. Shell:
The tiny shell is valvatoid, thin and translucent, the umbilicus is wide. The penis is flat, relatively thick at the basis with a small bulge and tapered at the distal end.
Differential Diagnosis: From Islamia the new genus can be distinguished by the penis, which is in Islamia bilobed.
Etymology: Named after the prefecture of Fez where the species has been collected.  Etymology: Named after the type locality. Habitat: Aouinat El Hajjaj is a rheocenous natural spring, located at Fez prefectur at an altitude of 409 m above sea level. The grain size of the bottom consists of stones, pebbles and sand, the vegetation of the banks is very heterogeneous and highly disturbed. Located in the Oued Wisslane watershed near a weekly market 'souk', which has subjected it to very strong anthropogenic action, through solid and liquid waste, habitat loss and water abstraction. In addition, the entire area could be suffering from agricultural runoff and drainage of water. Consequently, the population of Fessia aouintii n. gen. n. sp. would be highly vulnerable, and it is arguably the most threatened hydrobid of Morocco. Major efforts are needed for its conservation, including studies on its biological and ecological knowledge.
Description Shell: The tiny valvatoid shell is translucent with a silky surface. The 3.5 whorls are fast and rapidly growing separated by a deep suture. The body whorl is prominent and descends slowly on the shell wall. The shell is 0.8 mm high and 1.2 mm in diameter.
Animal: White with dark brown mantle pigmentation. Eye-spots large and visible.
Penis: Relatively small and flat with a broad basis and tapered at the distal end.
Operculum: Operculum flexible, without any peg, dark yellowish. Distribution: Morocco, only known from the type locality.