Volume 29

It is proposed to restore the old name of the genus Terenochiton for Leptochiton norfolcensis (Hedley et Hull, 1912). We also provide a new description for the genus since the old description does not reflect the main features associated with the development of the articulamentum. All valves of the genus have rudimentary unslitted insertion plates. Similar rudimentary insertion plates have evolved independently in different families of the primitive chitons.

An annotated and illustrated check-list of species of the subfamily Sphaeriinae (family Sphaeriidae) of the Kama region (the Middle Urals, Russia), with enumeration of species’ localities, is presented. After examination of own collections and critical assessment of literary data, 8 species from two genera (Musculium and Sphaerium) have been included into the final list. One of these species, Sphaerium asiaticum, is recorded for the first time from the studied area. The ecological characteristics of all species as well as remarks on their distribution within the region are provided. From the zoogeographical point of view, the most sphaeriine species of the studied area belong to the European-Siberian faunistic group.

The recent record of Xeropicta derbentina in the south of the Central Russian Upland (Belgorod Region, Russia) provides the opportunity to study the alien populations structure at the stage of colonization of a new territory. High intra-and interpopulation variability of the X. derbentina shell in different parts of the range is revealed. Based on the allozyme and PCR-ISSR analysis, it was established that native and adventitious populations of X. derbentina had the same level of genetic variability. The potential number of multilocus genotypes calculated for the Belgorod population indicate a further complexity of their genetic structure. The result of the ISSR analysis showed significant genetic differentiation (FST=0.746; p=0.01) of two adventive populations from the Belgorod Region, which indicates their different origin from the natural area.

The taxonomic position of the genus Culmenella within Hygrophila remains uncertain. The spermatozoa of Culmenella rezvoji, a species from the Far East of Russia, were examined using a combination of light, scanning and transmission electron microscopy with the objective to assess the utility of sperm characters for clarifying the phylogenetic relationships of the genus. The spermatozoa of C. rezvoji are divided into four regions: head, midpiece, glycogen piece and endpiece. The head contains a slender, cone-shaped acrosome and a conical nucleus with a sinistrally coiled keel. The acrosome consists of an apical vesicle and a thick-walled pedestal with an electron lucent canal partially filled with a patchy electron-dense material. The midpiece contains the mitochondrial derivative that encloses apically three parallel glycogen-filled tracts (helices) positioned in such a way that in the sperm cross section two helices lie opposite each other and equidistant from the third helix. The surface of the sperm above one of the helices forms a high, narrow ridge; the ridges above the remaining two helices have a much lower profile. The boundary between the midpiece and glycogen piece is demarcated by a constriction (annulus) consisting of an anterior electron-dense ring and a posterior conical cylinder connected to the ring with thin filaments. The structure of spermatozoa in Culmenella is consistent with the general pattern of sperm morphology common to all studied species of Hygrophila, but the spermatozoa of Culmenella also have distinctive characters (three glycogen helices and high-profile surface ridge in the apical portion of the midpiece) that should be potentially useful in resolving the taxonomic position of this genus.