Pisidium Pfeiffer, 1821

Bespalaya, Yulia V., Vinarski, Maxim V., Aksenova, Olga V., Babushkin, Evgeniy S., Gofarov, Mikhail Yu., Kondakov, Alexander V., Konopleva, Ekaterina S., Kropotin, Alexander V., Mabrouki, Youness, Ovchankova, Nadezda B., Palatov, Dmitry M., Sokolova, Svetlana E., Shevchenko, Alexander R., Travina, Oksana V., Taybi, Abdelkhaleq F., Soboleva, Alena A., Zubrii, Natalia A. & Bolotov, Ivan N., 2024, Phylogeny, taxonomy, and biogeography of the Sphaeriinae (Bivalvia: Sphaeriidae), Zoological Journal of the Linnean Society 201 (2), pp. 305-338 : 320-321

Genus Pisidium Pfeiffer, 1821 s.s.

Type species: Tellina amnica O.F. Müller, 1774

Diagnosis. Shell medium sized (up to 11 mm in length), elongately ovate to rounded-triangular. The beaks are narrow, weakly protruding, distinctly shifted to the posterior edge of the shell ( Fig. 5D ). The surface sculpture is well developed in the form of a regular ribbing. The cardinal tooth of the right valve and the inner cardinal tooth of the left valve are very sharply curved ( Fig. 6D ). Only the exhalant siphon is present. The branchial siphon is reduced, and only a branchial mantle opening is present. The inhalant water current enters via the branchial opening which has no tubular extension. The outer demibranch and inner demibranch are present ( Fig. 7D ). At the same time, the gills are characterized by a certain reduction of the outer demibranch (always shorter than the inner one) ( Fig. 7H ).

Reproductive biology: Synchronous brooders (embryos are developing within a distinct brood sac).

Distribution: This taxon embraces no less than three valid species, whose ranges encompass Europe, Siberia, the (Russian Far East, and North America ( Pisidium dubium ) ( Fig. 3C ; Table 1 ).

Аccording to Graf and Cummings (2023) and Vinarski and Kantor (2016), P. amnicum is widespread in the Palearctic being distributed from Europe to the Amur Basin. However, the number of available sequences from GenBank for P. amnicum is very restricted, and records of this species from other regions could not be excluded. The range of P. dilatatum covers North Europe, Siberia (Yamal Peninsula and Yakutia), and the Russian Far East (Kamchatka, Chukotka).

Figures

Figure 3. Maps of approximate geographic distribution of six genera of the Sphaeriinae in the world based on available 16S rRNA sequences: (A) Sphaerium; (B) Euglesa; (C) Pisidium s.s.; (D) Odhneripisiduim; (E) Hindupisidium; (F) Conventus.

Figure 5. Representatives of valid genera in the subfamily Sphaeriinae:(A) Euglesa casertana, Russia, Yamalo-Nenets Autonomus Okrug, Gydan Peninsula; (B) Hindupisidium nevillianum (Myanmar, Inle Lake); (C) Conventus conventus, Russia (Arkhangelsk Region, Novaya Zemlya); (D) Pisidium amnicum (Russia, Nenets Autonomus Okrug, Vashutkiny Lakes); (E) Sphaerium corneum (Russia, Arkhangelsk Region, Bolshoy Solovetsky Island); (F) Sphaerium lacustre (Russia, Irkutsk Region, Angara River). Photos:O.V.Aksenova. Scale bar: 1 mm.

Figure 6. Teeth morphology and shell pores of representatives of the genera in the subfamily Sphaeriinae: (A) Euglesa casertana (Russia, Yamalo-Nenets Autonomus Okrug, Yamal Peninsula); (B) Hindupisidium nevillianum (Myanmar, Inle Lake); (C) Conventus conventus (Russia, Arkhangelsk Region, Novaya Zemlya); (D) Pisidium amnicum (Russia, Nenets Autonomus Okrug, Vashutkiny Lakes); (E) Sphaerium corneum (Russia, Arkhangelsk Region, Bolshoy Solovetsky Island).Photos: O.V. Aksenova.Scale bars: teeth—0.5 mm; pores—20 µm. The left-hand, central column—right and left valves, respectively; the right-hand column—pores.

Figure 7. Anatomy of siphons and gills of representatives of the genera in the subfamily Sphaeriinae: (A) Euglesa casertana (Russia, Vaigach Island); (B) siphon of Hindupisidium nevillianum (Myanmar, Inle Lake); (C) siphon of Conventus conventus (Russia, Arkhangelsk Region, Novaya Zemlya); (D) siphon of Pisidium amnicum (Russia, Tyumen Region); (E) siphon of Sphaerium corneum (Russia, Arkhangelsk Region, Bolshoy Solovetsky Island); (F) siphon of Sphaerium lacustre (Russia, Irkutsk Region, Angara River); (G) gill with embryos of E. casertana (Russia, Vaigach Island); (H) gills with embryos of P.amnicum (Russia, Nenets Autonomus Okrug, Vashutkiny Lakes); (I) gills with embryos of S. lacustre (Russia, Irkutsk Region, Angara River). Photos:O.V.Aksenova. Scale bars: 0.5 mm.