Volume 16

Volume 16 Part 1-2

pp. 97 -

Size distribution, age, and sex ratio were studied for a population of baikalian endemic gastropod Maackia herderiana living on shallow-water rocky platform in South Baikal Lake. Six size groups were recognized. The age was determined from the number of annual growth rings on the shell. Each of groups I-V contained snails of two ages corresponding most probably to different generations: spring and autumn. Snails of 4 to 8 years old were assigned to the group VI. The sex ratio in M. herderiana was generally close to 1:1. A tendency to deficiency of females in older snails was similar to that described earlier by Kozminsky [2003] for Bithynia tentaculata. It could be explained by a longer life span of males and higher reproductive expenses of females.

Размеры, возраст и половая структура Maackia herderiana (Gerstfeldt, 1859) (Gastropoda: Caenogastropoda: Baicaliidae) из Южного Байкала
Максимова Н.В.; Ситникова Т.Я.;
pp. 105 -

Based on 63 nucleotide sequences 588 base pairs long of the fragment of mitochondrial gene coding for the 1st subunit of cytochrome с oxydase (CO1) of Baikalian endemic mollusc Baicalia carinata (Dybowski, 1875), we show that this species splits into three clades, which correspond to three populations: south (Bolshie Koty, Murinskaya Banka), north-west (from Maloe More to Id. Yarki) and north-east (from Gremyachinsk to Point Pongonie). Each clade includes sequences belonging to three different species of genus Baicalia. This fact indicate a lower degree of genetic differences (about 5%) between morphological species in comparison with differences between populations of the same species (up to 6.8%). We argue that the species of Baicalia Martens, 1876 occurred allopatrically in spite of their parapatric current distribution. Migration and possible inter-specific hybridization played important role in shaping of their current genetic polymorphism.

Исследование популяционного генетического полиморфизма эндемичного байкальского вида Baicalia carinata (Mollusca, Caenogastropoda).
Перетолчина Т. Е.; Ситникова Т. Я.; Щербаков Д. Ю.;
pp. 113 -

The shell pores of Baikalian euglesid bivalves from the littoral of South Baikal Lake were for the first time studied with the SEM. It was shown that the pores are unevenly distributed in the 8 species studied [Henslowiana semenkevitschi (Lindholm, 1909), H. trigonoides (W. Dybowski, 1902), Euglesa granum (Lindholm, 1909), E. minuta (Kozhov, 1936), E. korotnevi (Lindholm, 1909), E. platyvalva (Slugina et Starobogatov, 1994), Cingulipisidium koshovi (Starobogatov et Streletzkaja, 1967), Conventus raddei (W. Dybowski, 1902)]. In subumbonal part of E. granum and E. minuta shells, the pore density is 1.5 times higher; the pore width and height in E. minuta are about 2 times more above the mantle line than in marginal part of the shell. The pores in subumbonal part of E. platyvalva shell are, on the contrary, 1.5 rarer than above the mantle line and 2.6 times rarer than at the shell margin. Among the species studied, only E. platyvalva has pores between the mantle line and the lower valve margin, which has not been previously found in the family Euglesidae. In the subumbonal part of this species shell the largest pores were observed: 6.34 μm, whereas the smallest pores in this part of the shell were found in С. kozhovi (2.22 μm). The pores of three species, H. semenkevitschi, E. granum, C. koshovi, are surrounded by additional thickening on inner side of valves.

Поры в раковинах двустворчатых моллюсков семейства Euglesidae (Mollusca: Bivalvia) из Южного Байкала.
Слугина З. В.; Ситникова Т. Я.; Семитуркина Н. А.;
pp. 119 -

The recently published catalogue of the former USSR molluscs [Kantor, Sysoev, 2005] unfortunately provides incomplete data on modern distribution of many species of land molluscs on the territory of Ukraine. Some species are not mentioned for Ukraine (Deroceras caucasicum, Limax maximus, Malacolimax tenellus, Arion circumscriptus, Cepaea hortensis, C. nemoralis, Stenomphalia ravergiensis) or for countries of the former USSR (Acicula perpusilla, Chondrula microtraga, Thoanteus ferrarii, Helicodiscus singleyanus, Daudebardia rufa, D. brevipes, Aegopinella nitens, Ae. nitidula, Vitrea diaphana, Deroceras turcicum, Limax bielzi, Arion distinctus). Faunistic investigations of Ukrainian malacologists allow to supplement essentially the catalogue data.

О распространении некоторых видов наземных моллюсков на территории Украины.
Сверлова Н. В.;