Short Communication |
Corresponding author: Hanane Rassam ( hananerassam@gmail.com ) Academic editor: Oana Teodora Moldovan
© 2020 Hanane Rassam, Soumia Moutaouakil, Hassan Benaissa, Christian Albrecht, Mohamed Ghamizi.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Rassam H, Moutaouakil S, Benaissa H, Albrecht C, Ghamizi M (2020) First record of Pisidium subtruncatum Malm, 1855 (Bivalvia, Sphaeriidae) in an African cave. Subterranean Biology 34: 99-108. https://doi.org/10.3897/subtbiol.34.50916
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Studies on the bivalve family Sphaeriidae in North Africa are very limited at the surface water level, but even more for caves. During an expedition in 2019 to the Ait M’hamed cave (Oum Er Rabia Basin), six specimens of the genus Pisidium were collected. Morphometric and genetic analyses showed that these individuals belong to the species Pisidium subtruncatum Malm, 1855. This work is the first step towards future exploration of cave Sphaeriidae in North Africa.
Molluscs, Subterranean, Invertebrates, Biospeleology, Ait M’hamed, Morocco
Pisidium is a genus of freshwater bivalves belonging to the family Sphaeriidae that includes the smallest bivalves on Earth. Despite their small size, Pisidium species can be used for bioindication studies (
In May 2019, we prospected the Ait M’hamed cave. This cave is located in Oum Er Rabia basin at 1693 m of altitude (31°52'48"N, 06°27'02"W). The cave is dug at the bottom of a cliff in the calcareous of Bajocian – Bathonian period with horizontal stratification (
Measurements of physical and chemical parameters at two localities in the cave system (see Fig.
H (%) | T(°C) | T(°C) of water | Dissolved oxygen. (mg/l) | Conductivity (µS/com) | pH | Nitrites (g/mol) | Phosphate ion (g/mol) | Ammonium (g/mol) | |
---|---|---|---|---|---|---|---|---|---|
Cave entrance | 28 | 20.7 | 20 | 5.32 | 421 | 7.2 | 0.08 | 0.11 | 0.03 |
Waterfall | 28 | 19.1 | 21.6 | 4.65 | 432 | 7.09 | 0.071 | 0.06 | 0.05 |
The sampling was carried out with a sieve of 200 µm of diameter in muddy sediments and lead to the collecting of 6 specimens belonging to the genus Pisidium (Fig.
In the laboratory, the identification of the specimens was based on morphological characters following the descriptions of
Soft bodies were extracted for genetic analysis in order to confirm morphological identification. DNA isolation followed a CTAB protocol (
Morphometric results of the four specimens collected showed that they have a length ranging between 3.49 and 1.91 mm and height between 2.93 and 1.62 mm. The shell is silky with slight striations and the umbo is narrow and located posteriorly. The shape of the shell is sub-angulated, the most extreme point of the anterior part is located lower than the middle of the shell height (Figs
N | L | H | LA | LP | LE | LL | LH | HH | |
---|---|---|---|---|---|---|---|---|---|
Mean ± SD | 4 | 2.96 ± 0.81 | 2.28 ± 0.53 | 1.8 ± 0.64 | 1.16 ± 0.31 | 0.81 ± 0.24 | 0.48 ± 0.09 | 1.44 ± 0.38 | 0.15 ± 0.05 |
Genetic results did not contradict the identification of the species as P. subtruncatum and, as presented in the list of significant BLAST hits (Table
List of the first five significant BLAST hits (NCBI GenBank accessed on 15/06/2019).
Description | Max score | E value | Percent identity | Accession |
---|---|---|---|---|
Pisidium subtruncatum isolate 17469 histone 3 (H3) gene, partial cds | 599 | 3e-167 | 99.39% | KU376244.1 |
Pisidium atkinsonianum isolate 6024 histone 3 (H3) gene, partial cds | 595 | 3e-166 | 99.39% | KU376227.1 |
Pisidium viridarium isolate 15834 histone 3 (H3) gene, partial cds | 590 | 2e-164 | 99.09% | KU376246.1 |
Pisidium personatum isolate 17456 histone 3 (H3) gene, partial cds | 590 | 2e-164 | 98.78% | KU376241.1 |
Pisidium casertanum isolate 17462 histone 3 (H3) gene, partial cds | 586 | 2e-163 | 98.78% | KU376228.1 |
P. subtruncatum was already recorded in a river of the Sebou basin (
In general, the Sphaeriidae family is neglected in North Africa and studies on this group of benthic organisms are very limited compared to other taxa. The originality of this work consists in the recording for the first time of a member of the Sphaeriidae family in an African cave and to our knowledge the first record of P. subtruncatum in a cave. Studies such as ours reported here should be expanded to other caves in Morocco (Fig.
We thank Dr. Michael Zettler (Warnemünde, Germany) for confirming the identification of the species.