Sphaerium Scopoli, 1777

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 : 316-320

Genus Sphaerium Scopoli, 1777

Type species: Tellina cornea Linnaeus, 1758 .

Diagnosis: Shell large-sized (shell length in adults varies between 6 and 25 mm), rounded to ovate in shape, typically thick walled ( Fig. 5E ). The beaks rounded and slightly prominent or narrow, pore density varies among species ( Fig. 5E , 6E ). Cardinal and lateral

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teeth well developed ( Fig. 6E ). Nephridia moderately elongated. Two siphons (exhalant and inhalant) are present ( Fig. 7E ). The outer and inner demibranch relatively well developed.

Reproductive biology: The species of the genus are asynchronous brooders (they incubate their progeny in several separate brood sacs).

Distribution: Subglobal. This genus is known from Eurasia, Africa ( Sphaerium stuhlmanni ), North and South America ( Sphaerium argentinum ), East Africa, New Zealand ( Sphaerium novaezealandiae ), and Australia ( Sphaerium tasmanicum ) ( Fig. 3A ).

Sphaerium nitidum Clessin in Westerlund, 1876

( Fig. 8 )

Sphaerium nitidum Westerlund, 1876: 97–104 .

Type series: The lectotype [pair of valves, designated by Starobogatov in 1968] and eight paralectotypes are deposited in National Museum of Natural History , Stockholm, Sweden

( SMNH) nos 4725–4728 (see Fig. 8A ). The lectotype was collected in Dudinka.

Type locality: Russia, Krasnoyarsk Territory, the Yenisei River near Dudinka (‘Jenissei, Dudino … (lat. 69°15 ʹ) … norr om Lusino … (lat. 68°40 ʹ); Westerlund, 1877: 67’) .

Material examined: Russia: Vaygach Island, Talatinskoe Lake, VIII.2010, Aksenova , Bespalaya leg., five specimens (lot nos INEP-615, INEP-619); Yamal Peninsula , Seyaha River Basin , VIII.2014, Zubrii leg., 151 specimens (lot nos RMBH MSph-0011, MSph-0014, MSph-0015); Gydan Peninsula VII.2017, Sokolova & Shevchenko leg., 23 specimens (lot nos RMBH MSph 372), Yugorsky Peninsula VIII.2015, Spitsyn leg., two specimens (lot nos RMBH MSph-0087, MSph-0037), Krasnoyarsk Region, Taymyr Peninsula, Dudinka River , VII.2018, Aksenova, Sokolova, Shevchenko, Travina leg., three specimens (lot no. RMBH MSph-0415), Chukotka Peninsula, Amguema River Basin, VII.2019, Aksenova leg., four specimens (lot nos RMBH MSph-0494/2, MSph-0497/1) .

Description: Shell medium sized (mean length ± SD 3.9 ± 1.1 mm, min–max 1.9–6.5 mm, N = 151), rectangular, with a characteristic concentric sculpture around the beaks ( Fig. 8A–C ). The beaks are rounded and slightly prominent. The cardinal tooth of the right valve is slightly curved, and the weaker split on the posterior end has divergent branches. The inner cardinal tooth of the left valve is thin, curved, and slightly S shaped ( Fig. 8C ). The outer cardinal tooth of the left valve is thin, slightly curved, and shorter than the inner cardinal tooth ( Fig. 8C ). The inner side of the valves is characterized by a high pore density. The nephridia are elongated ( Fig. 8C, D ).

Distribution: Kolguev Island, Vaygach Island, Yamal Peninsula, Gydan Peninsula, Yugorsky Peninsula, the Lower Yenisei Basin, Taymyr Peninsula, Chukotka Peninsula. According to some authors, S. nitidum was recorded in North America ( Mackie et al.

1980, Mackie 2007). However, their records are not confirmed by genetic data.

Comments: The systematic position of S. nitidum has remained controversial to date ( Korniushin 2001, Bespalaya et al. 2015a). The specimens studied by us correspond to the morphological and anatomical diagnosis given in the original description of S. nitidum ( Fig. 8A ; Westerlund 1876) and the re-description of this species published by Odhner (1921) ( Fig. 8D ). In addition, we obtained molecular-genetic data on S. nitidum from the Arctic region ( Bespalaya et al. 2015a, 2022). The sequenced individuals from Vaygach, Yugorsky Peninsula, Yamal Peninsula, and Gydan Peninsula share the same 16S rRNA haplotype, which is identical to S. nitidum sequences from its type locality (Yenisei River, Dudinka Town, Krasnoyarsk Region) ( Fig. 2 ), and is separated by three nucleotide substitutions from haplotypes of this species from Chukchi Peninsula and Kolguev Island ( Bespalaya et al. 2022).

Figures

Figure 2. The phylogeny of the subfamily Sphaeriinae recovered from ML analysis (W-IQ-TREE) and obtained for the complete dataset of mitochondrial and nuclear sequences (16S rRNA+28S rRNA). Black numbers near nodes are bootstrap support values (BS)/ Bayesian posterior probabilities (BPP). The new taxa are highlighted in red. Subgenera are marked by curly brackets.

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.

Figure 8. (A) The lectotype of Sphaerium nitidum (Russia, Krasnoyarsk Region, Dudinka) (SMNH No.4726); (B) S.nitidum, shell [Russia, Saint Petersburg, Staraya Derevnya (Old Village)] (ZIN No. 23); (C) S. nitidum, shell, nephridia, and teeth morphology (Russia, Vaigach Island, Yangoto Lake); (D) Nephridia, dorsal view of S. corneum (left) and S.nitidum (right) by Odhner (1921). Photos: A. Persson (A), P.V. Kijashko (B) and O.V. Aksenova (C). Scale bars: 1 mm.