Euglesa ljovushkini (Starobogatov, 1962)

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 : 328

Euglesa ljovushkini (Starobogatov, 1962)

( Fig. 9E )

Pisidium ljovuschkini Starobogatov, 1962: 49–50 , fig. 3.

Type series: The holotype is kept in ZIN, no. 1 in the systematic catalogue.

Type locality: Abkhazia, Tsebelda Cave (43°01 ʹ 52.30″N 41°16 ʹ 08.92″E) .

Material examined: Abkhazia, Gulripshi District, Tsebelda Cave , Tsabal village, 31.I.2012, Palatov leg., 14 specimens (lot nos RMBH MSph-292, MSph-292/1-1, MSph-292/1-2, MSph-293, MSph-293-1), 01.II.2018, Palatov leg., 15 specimens (MSph-334) , Abkhazia, GudautaDistrict, BachaCave, Otkharavillage , 01.II.2018, Palatov leg., 13 specimens (lot no. RMBH MSph 732) , Abkhazia, Gulripshi District, Shakuraisi, stream in the Nizhne-Shakuranskaya Cave , 13.IV.2012, Palatovleg., 15 specimens (lotnosRMBHMSph-294, 294/1-2) ; Abkhazia, Gulripshi District, Shakuraisi, stream in the Sredne-Shakuranskaya Cave , 02.II.2018, Palatov leg., three specimens (lot no. RMBH MSph-0335), Georgia, Samegrelo-ZemoSvaneti , Martvili District , Chortzkhu Cave , 02.II. 2017, Palatov leg., one specimen (lot no. RMBH MSph-0297) .

Description: The shell is small (mean length ± SD 2.3 ± 0.2 mm), round-oval in shape, not convex ( Fig. 9E ). The beaks are rounded, not prominent, offset to the posterior edge of the valves ( Fig. 9D, E ). The cardinal tooth of the right valve is long, curved in the middle part. The cardinal teeth of the left valve are short, straight, and slanted ( Fig. 10D ). Lateral teeth are short.

Distribution: Transcaucasia.

Comment: The 16S and 28S rRNA sequences of samples from the type locality of Euglesa ljovushkini have no analogues in GenBank. According to Starobogatov (1962), another species morphologically similar to Euglesa cavatica Zhadin, 1952 was found in samples from the Tsebelda Cave (the type locality of E. ljovushkini ). Euglesa cavatica was described by Zhadin (1952), based on conchological features; the anatomical structure has not been studied. The type locality of E. cavatica is Krasnodar Region, a cave in the ravine of the upper reaches of the Khosta River (Zhadin 1952). The author gives a morphological and anatomical description of these specimens. According to Starobogatov (1962), the specimens found in the Tsebelda Cave have two siphons (exhalant and inhalant), and well-developed demibranchs, which is typical for subgenus Pisidium s.s. (= Eupisidium ). At the same time, the author hypothesized that the discovered specimen may be a distinct species (Starobogatov 1962). Based on the comparison of anatomical and morphological data obtained by us, no specimen sampled in Tsebelda Cave can be identified as E. cavatica , since they have obvious morphological and anatomical differences (Supporting Information, Fig. S2E, F ). In addition, in a sample from the Nizhne-Shakuranskaya Cave, one right valve of Pisidium s.l. was found (Starobogatov 1962). According to the author it belongs to a new, undescribed species of Pisidium . Starobogatov (1962) noted the morphological similarity of the discovered valve with E. ljovushkini , except the structure of the teeth. All the samples from the Nizhne-Shakuranskaya Cave studied by us were identified as E. ljovushkini .

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.