Euglesa subterranea (Zhadin, 1932)

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 : 329-330

Euglesa subterranea (Zhadin, 1932) ( Fig. 9G )

Pisidium subterraneum Zhadin, 1932: 13 , pl. 1, fig. 2.

Type series: The type series includes the holotype and eight paratypes in ZIN, nos 1–3 in the systematic catalogue .

Type locality: Georgia, Tskhal-Tsiteli Cave near Kutaisi City (= ‘Rion-Höhle’ sensu Shadin 1932) .

Material examined: Georgia, Imereti, Tskhal-Tsiteli Cave near Kutaisi City , VIII.2016, Palatov leg., two specimens (lot no. RMBH MSph-295) .

Description: The shell is small (mean length ± SD 2.75 ± 0.1 mm), round-oval in shape ( Fig. 9G ). The beaks are rounded, not prominent, located in the middle of the valves ( Fig. 10G ). The cardinal tooth of the right valve is curved, and thickened on the posterior end. The cardinal teeth of the left valve are short, slightly curved ( Fig. 10F ). Lateral teeth are long.

Distribution: Possibly endemic to Georgia.

Comment: The 16S and 28S rRNA sequences from type locality of E. subterranea have no analogues in GenBank and are more closely related to E. ljovushkini ( Fig. 2 ). However, these species differ by having a different structure to the cardinal teeth (see descriptions) ( Fig. 10D, F ). Our data correspond with the opinion of Starobogatov (1962), who revealed morphological differences between these species.

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 9. Shells of species, re-described in this research: (A) Euglesa khurbaensis (RMBH No. MSph-707, Russia, Primorsky Territory); (B) E. khurbaensis (RMBH No.MSph-707/2, Russia, Primorsky Territory); (C) E.lindholmi (RMBH No. MSph-370, Russia, Gydan Peninsula); (D) E. ljovushkini (RMBH No. MSph-335, Abkhazia); (E) E. ljovushkini (RMBH No. MSph-335/2, Abkhazia); (F) E. hinzi (RMBH No. MSph- 366, Russia, Gydan Peninsula); (G) E. subterranea (RMBH No. MSph-295, Georgia, Imereti); (H) E. nordenskioldi (Russia, Vaygach Island). Photos: O.V. Aksenova.Scale bar: 1 mm.

Figure 10. Morphology and anatomy of re-described species discussed in this research (teeth morphology and shell pores, anatomy of gills and siphons): (A) Euglesa hinzi (RMBH No. MSph-366, Russia, Gydan Peninsula); (B) E. khurbaensis (RMBH No. MSph-707/2, Russia, Primorsky Territory); (C) E.lindholmi (RMBH No.MSph-370, Russia, Gydan Peninsula); (D) E. ljovushkini (RMBH No. MSph-335, Abkhazia); (E) E. nordenskioldi (Russia, Vaygach Island); (F) E.subterranea (RMBH No. MSph-295, Georgia, Imereti). Photos: O.V. Aksenova. Scale bar: 0.5 mm.