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A NEW GENUS AND NEW SPECIES OF SPRINGSNAILS (GASTROPODA, HYDROBIIDAE) FROM NORTH-EAST MOROCCO
Abdelkhaleq F. Taybi1 , Peter Gloer2 , Youness Mabrouki3 *
1Mohammed First University, Morocco 2Biodiversity Research Laboratory, Germany 3Sidi Mohamed Ben Abdellah University, Morocco *e-mail: youness.mabrouki@usmba.ac.ma
Received: 28.03.2023. Revised: 24.06.2023. Accepted: 27.06.2023.
Recent field surveys on snails conducted in the oriental region of Morocco have led to the discovery of a new species belonging to a new genus, described here as Znassela bnisnasensis gen. et sp. nov. It can be distinguished from the other hydrobiid snails by the morphology of the shell and male anatomy. The new hydrobiid snail differs mainly by its elongated ovate shell with 4.5 whorls, slightly convex with a shallow suture, and by the penis showing a swelling near the penis tip; the latter has two penial appendices located on the same side. Znassela bnisnasensis has been found in the Beni-Snassen massif, considered a Protected Area in the north-eastern part of Morocco and which is a Site of Ecological and Biological Interest (known as SEBI or SIBE). Photographs of the holotype and paratypes are presented, with the penis morphology, habitat and information on its autecology.
Key words: Beni-Snassen massif, crenobiotic species, freshwater gastropod's endemism, North Africa, Protected Area, springsnail
Introduction
The freshwater gastropod fauna of the world comprises more than 4000 validly described species. They occur on all continents except Antarctica and in almost all types of aquatic habitats (Strong et al., 2008). Many of the freshwater gastropods, especially hydrobiids, which are typically habitat specialists, have narrowly ranged and restricted geographic distribution areas, which make them more vulnerable to human-related threats (Ponder & Walker, 2003; Lydeard et al., 2004).
In North Africa, Morocco is recognised as a hotspot of freshwater gastropod diversity (Ma-brouki et al., 2020, 2022a; Gloer, 2022). The main part of this high diversity concerns the springsnail family, Hydrobiidae Stimpson, 1865 (Mabrouki et al., 2022b; Taybi et al., 2022). Most of these hydro-biid snails inhabit the relatively well-watered parts of the Mediterranean-Northern part of Morocco and occupy very narrow ranges.
At present, the Hydrobiidae family is represented by 19 genera in Morocco, most of which have been described recently (Gloer et al., 2020a,b; Boulaassafer et al., 2021; Mabrouki et al., 2021; Taybi et al., 2023a). This paper is a direct continuation of this series of discoveries. This research, conducted in north-eastern Morocco, has revealed a new species belonging to a new genus. Therefore, the main aim was to describe it.
Material and Methods
Sampling
Field surveys were conducted in 2014-2023, when several localities were prospected along the northern part of Morocco, with a special focus on Protected Areas. Most of these sampling sites were visited several times. Benthic invertebrate samples (including molluscs) were taken with «Surber» sampler (ENTOMO-SILEX, France). The quantitative samples (about eight) in various microhabitats presented on the site have been taken against the water current. The choice of selected microhabitats was based on their biogenic capacity suitable to aquatic life. The main part of qualitative benthic fauna samples were taken by nets, dip nets and forceps. The samples have been fixed in 75% ethanol.
The dissections and measurements of the genital organs and the shells were carried out using a stereomicroscope (Leica M205C) with a digital camera (Leica DMC5400). The type material is stored in the Zoological Museum of Hamburg, Germany (ZMH). Water parameters such as conductivity, pH, and dissolved oxygen were measured in situ with a multiparametric measuring device (WTW, Multi-Line P4). The other parameters, such as ammonium and biological oxygen demand (BOD5), were measured in the laboratory. Two replicates of water samples from each station were taken in 500-ml polyethylene bottles. Water
samples were preserved with 2 ml of concentrated hydrochloric acid (pH = 2). According to the ISO 5667-6 (1990), ISO 5667-2 (1991) and ISO 5667-3 (1994) standards, they were conveyed to a cooler at a low temperature (± 4°C) to stop the metabolic activities. The variables were determined according to AFNOR (1997) standards and Rodier et al. (1996).
Study area
The Beni-Snassen is a Protected Mountainous Area located in the province of Berkane (34.812111° N, 02.401371° W) in the oriental region of Morocco (Fig. 1). It covers an area of more than 61.50 km2, considered as a Site of Biological and Ecological Interest (https://ma.chm-cbd.net/manag_cons/esp_prot/sibe_ma/sibe_ cont_ter/beni-snassene-14/sibe_14) and protected by the Moroccan government. The Beni-Snassen Mountains form mainly a limestone mountain range with the highest peak at 1535 m a.s.l. at Ras Foughal. They form a set of reliefs that run along the coast, delimited to the north by the Mediterranean Sea, to the south by the River Isly, to the west by the River Moulouya, and to the east by the River Kiss, which runs along the Algerian border about 12 km away. The bioclimatic floors
vary between the temperate semi-arid and the fresh sub-humid. Due to the increase in rainfall and humidity in the Beni-Snassen mountains, the study area is relatively well-watered in a semiarid context (Agbani et al., 2003).
Results
Phylum Mollusca Cuvier, 1795 Class Gastropoda Cuvier, 1795 Superorder Caenogastropoda Cox, 1960 Superfamily Truncatelloidea Gray, 1840 Family Hydrobiidae Stimpson, 1865
Description of the new genus
Znassela Taybi, Gloer & Mabrouki gen. nov. Type species. Znassela bnisnasensis Taybi, Gloer & Mabrouki sp. nov.
Diagnosis. The shell is elongated ovate, and the penis has two appendices attached on the same side. The penis morphology is a typical character for this species, not known in any other hydrobiid species. This feature justifies the description of a new genus, as it is known that hydrobiid genera can be identified by the shell shape in combination with the penis morphology (Radoman, 1983; Szarowska, 2006; Gloer, 2022).
Fig. 1. Location of the Beni-Snassen Protected Area, the type locality of Znassela bnisnasensis gen. et sp. nov., and its habitat.
Differential diagnosis. The new genus has an elongated ovate shell with 4.5 whorls, slightly convex with a shallow suture. The penis has a swelling near the penis tip and has two penial appendices. Znassela gen. nov. can be distinguished from the other elongated Hydro-biidae by shell morphology and male copulato-ry organ. The new genus is more similar to the genus, recently described from Morocco, Agh-balia Gloer, Mabrouki & Taybi, 2020. The latter has a smaller penis with two large appendices on each side; one of them is larger than the penis itself. Another similar genus from Tunisia, Bullaregia Khalloufi, Bejaoui & Delicado
2017, has a straight border of the aperture from lateral view; the penis is long and slim and has only one penial appendix. The genus Corro-sella Boeters, 1970, which occurs in Morocco, Spain and France, has a triangular penis without penial appendices; the apex of the shells is often corroded in Moroccan specimens. Finally, in the genus, recently described from Morocco, Gafaita Taybi, Mabrouki & Gloer, 2023, the shell has a shallow suture, and the triangular penis has only one large triangular appendix.
Etymology. The new genus was named in honour to the Protected Area and the SIBE of Béni-Snassen.
Key to the hydrobiid genera of Morocco with elongated shells
1. Body is non-pigmented; eye spots are absent (stygobic)......................................................................................2
- Body is pigmented; eye spots are present (crenobiotic)........................................................................................4
2. Shell has more than five whorls............................................................................................................................3
- Shell has less than five whorls..................................................................................................................Mahrazia
3. Shell is slim, and has regularly growing width........................................................................................Heideella
- Shell is not slim, and has penultimate whorl slightly broader than the body whorl.................................Atebbania
4. Shell has convex whorls and a deep suture...........................................................................................................5
- Suture is not deep.........................................................................................................................................Gafaita
5. Penis has no appendix............................................................................................................................Corrosella
- Penis has appendix................................................................................................................................................6
6. Penis has two appendices, one on each side.............................................................................................Aghbalia
- Penis has two appendices on the same side................................................................................Znassela gen. nov.
Description of the new species ed in the type locality and stored in the Zoological Znassela bnisnasensis Taybi, Gloer & Ma- Museum of Hamburg (ZMH 141469). Paratypes: brouki sp. nov. ten paratypes are stored in the Zoological MuseType material. One holotype (Fig. 2) and 28 um of Hamburg (ZMH 141470), eight in the per-paratypes (Fig. 3) were collected on the type lo- sonal collection of Peter Gloer, and ten specimens cality and preserved in ethanol. Holotype: shell is in the personal collection of Youness Mabrouki 1.97 mm in height and 1.11 mm in width, collect- and Abdelkhaleq Taybi.
Fig. 2. Znassela bnisnasensis gen. et sp. nov. Designations: A - shell of the holotype; B, C - penis (p), with penial appendices (pa).
Fig. 3. Paratypes of Znassela bnisnasensis gen. et sp. nov.
Type locality. It is the Beni-Snassen SIBE, Ain Bni Mahfoud spring (34.891389° N, 02.213333° W), Berkane province, oriental region of Morocco. It was collected on 02.06.2022.
Description
Conchological features. The elongated ovate shell has 4.5 whorls, slightly convex with a shallow suture. The aperture is ovate, tapered at the top and rounded to angled (Fig. 2A, Fig. 3). The umbilicus is closed. The shell is 1.68-1.97 mm in height and 1.02-1.11 mm in width. Shell measurements are presented in Table 1. The corneous operculum is ovate, with a rounded angle at the top, smooth and thin, and brown in colour.
Soft body. The penis has two appendices (Fig. 2B, C), which has a swelling near the tip. The penis itself is larger than the appendices; the penial appendices are located on the same right side of the penis, one after the other. Penis is attached well behind right eye.
Etymology. The new species was named in honour of the Beni-Snassen massif.
Habitat. Ain Bni Mahfoud is a permanent rheocrenous spring, located in the Beni-Snassen massif at altitude of 472 m a.s.l. The water of the
spring is routed through concrete pipes to a small retention basin before being redistributed again. The slope of the flow and the speed of the current velocity are important. The ground substrate is made up by pebbles and gravel with plant debris. The banks are naturally covered by dense shore vegetation consisting mainly of Rubus camptos-tachys G.Braun and Smilax aspera L. The vegetation of this forest area is composed by typically Mediterranean scrubland species, such as Pistacia lentiscus L., Tetraclinis articulata (Vahl) Mast., and Ulex parviflorus Pourr. The analysis of the physicochemical parameters of the water, sampled in the habitat of Znassela bnisnasensis gen. et sp. nov. at Ain Bni Mahfoud spring, revealed a good hydrological quality (Table 2), according to the Moroccan Surface Water Guidelines (MSWG) of good quality.
Nomenclatural acts. This study and its nomenclatural acts have been registered in the ZooBank. The ZooBank Life Science Identifiers (LSID) for this publication are https://zoo-bank.org/NomenclaturalActs/c145a344-caab-4dae-b68f-1b0894a77f39, and https://zoobank. org/NomenclaturalActs/E1A6E04F-DC34-4EFB-8438-CE15231B16A8.
Table 1. Shell measurements (N = 20; the measurement accuracy is 0.05) of Znassela bnisnasensis sp. nov.
Shell measurements Minimum Maximum Mean Standard deviation
Shell height, mm 1.69 2.02 1.89 0.12
Aperture height, mm 0.70 0.84 0.79 0.05
Spire height, mm 0.99 1.18 1.10 0.07
Shell width, mm 0.92 1.10 1.04 0.06
Aperture width, mm 0.38 0.45 0.43 0.02
Table 2. Mean values for the physical and chemical water parameters measured at the sampling locality of Znassela bnisnasensis gen. et sp. nov., and their values (according to Moroccan Surface Water Guidelines)
Factor pH Conductivity Dissolved oxygen bod5 Ammonium
Mean 7.2 245 ^S x cm-1 6.3 mg x l-1 4.5 mg x l-1 0.01 mg x l-1
MSWG 6.5-8.5 100-1300 ^S x cm-1 > 7-5 mg x l-1 < 3-5 mg x l-1 < 0.1-0.5 mg x l-1
Note: MSWG - Moroccan Surface Water Guidelines, BOD5 - biological oxygen demand.
Associated species. The new taxon was found with other aquatic Gastropods, such as Physella acuta (Draparnaud, 1805), Ancylus sp., Melanopsis spp., and various aquatic invertebrates, including annelids (Helobdella stagnalis (Linnaeus, 1758)), crustaceans (Potamon alge-riense Bott, 1967), Ephemeroptera larvae (Cae-nis luctuosa (Burmeister, 1839), Baetis spp.), Odonata larvae (Trithemis sp., Sympetrum sp., Orthetrum sp.). In addition, some Diptera larvae were found on the type locality (e.g. Chironomi-dae and Culicidae). Two aquatic vertebrate species were found in the Ain Bni Mahfoud spring, Discoglossus pictus Otth, 1837 and Pelophylax saharicus (Boulenger, 1913).
Discussion
Previous findings has raised the known biodiversity of the family Hydrobiidae s.str. in Morocco to 20 genera (Mabrouki et al., 2022c,d; Taybi et al., 2023a). To date, the new genus and species are restricted to their type locality in the BeniSnassen. This geographical barrier is also known as a habitat for other endemic hydrobiid species, such as Aghbalia aghbalensis Glöer, Mabrouki & Taybi, 2020, Pseudamnicola tafoughaltensis Taybi, Glöer & Mabrouki, 2022, Mercuria mida-rensis Boulaassafer, Ghamizi & Delicado, 2018, and M. gauthieri Glöer, Bouzid & Boeters, 2010 (Mabrouki et al., 2020, 2021; Taybi et al., 2022).
The Beni-Snassen massif is a cornerstone of biodiversity conservation in northern Morocco. This mountain range represents an enclave of rich biodiversity, where many forest and mountain species occur, including mammals, birds, reptiles, and amphibians (Aulagnier et al., 2015; Mediani et al., 2015; Mabrouki et al., 2019). In addition,
due to the permanent mountain stream, River Zeg-zel, the massif also has a particular hydrological value due to its functional role in supplying the River Moulouya and the Beni-Snassen aquifer, corresponding to the largest underground water reservoir in the north-eastern Morocco.
In Morocco, a major management concern of the Protected Areas, such as Ramsar Sites and SIBE, is the impact of alien species, which can prey on or, perhaps, outcompete native biodiversity, including freshwater mollusc species (Taybi et al., 2021, 2023b,c). These areas are a home to 41 alien animal species belonging to various taxo-nomic groups (Taybi et al., 2023b). Management priorities must include the reduction or elimination of alien species spread in Moroccan freshwater Protected Areas.
Conclusions
In the last years, the hydrobiid springsnail fauna of Morocco has received a considerable attention in terms of species discoveries. It is more likely that the number of springsnail diversity, known to occur in Morocco, will increase with further intensified studies and collecting expeditions, which are urgently needed. Indeed, invasive species are not the only problem facing the freshwater biodiversity in the Eastern Morocco. In addition to the considerable anthropogenic pressures, many springs in the Beni-Snassen massif have dried up due to years of water withdrawals and dry weather because of climate change; this can be a serious problem facing the crenobiotic species of North Africa in general. More efforts are needed for better understanding and knowing more about this invertebrate group, which receives less conservation concerns compared to the vertebrates.
Acknowledgements
We sincerely thank the Editor-in-Chief and two anonymous reviewers, who have greatly improved this paper at the initial stage.
References
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НОВЫЙ РОД И ВИД УЛИТОК (GASTROPODA, HYDROBIIDAE) ИЗ СЕВЕРО-ВОСТОКА МАРОККО
А. Ф. Тайби1 , П. Глёэр2 , Ю. Мабруки3
1Первъш университет Мохаммеда, Марокко 2Лаборатория исследования биоразнообразия, Германия 3Университет Сиди Мохамеда бен Абдаллы, Марокко *e-mail: youness.mabrouki@usmba.ac.ma
Полевые исследования, проведенные на востоке Марокко, привели к описанию нового вида, принадлежащего к новому роду, описанному здесь, как Znassela bnisnasensis gen. et sp. nov. От других гидробиид его отличает морфология раковины и анатомические признаки самцов. Znassela bnisnasensis отличается преимущественно удлиненно-яйцевидной раковиной с 4.5 оборотами, слегка выпуклой, с неглубоким швом, и пенисом с припухлостью у кончика пениса; последний имеет два пениальных отростка, расположенных на одной стороне. Znassela bnisnasensis была обнаружена в массиве Бени-Снассен, который является особо охраняемой природной территорией в северо-восточной части Марокко и представляет собой объект экологического и биологического интереса (известный как SEBI или SIBE). В статье представлены фотографии голотипа и паратипов, морфология полового члена, среда обитания и информация о его аутэкологии.
Ключевые слова: кренобиотический вид, массив Бени Снассен, особо охраняемая природная территория, Северная Африка, улитка, эндемизм пресноводных брюхоногих
