Backeljau T (18 results)

This paper deals with the infrageneric systematics of the genus Arion. It presents a historical account, after which the infrageneric position of A. intermedius is discussed. This species is included in the subgenus Kobeltia of which the type species is reconsidered. Next, a discussion on the infrageneric allocation of A. lusitanicus and A. flagellus is provided. Both species are provisionaolly placed in the subgenus Mersarion, which in turn may be grouped with Arion s.s. in the chromosomal group Lochea (n=27). This classification relies on chromosomal, electrophoretic, genital and morphological characters. Yet, the currently available data do not allow a reliable phylogenetic analysis, so that no taxonomic ranks are attributed to the retained groupings. Nevertheless, some tentative phylogenetic and evolutive hypotheses are presented. Thereby special attention is paid to 1) chromosome numbers, 2) electrophoretic data, 3) breeding systems, 4) spermatophores and 5) the complexity of genitalia and mating behavior. 34 pp., 19 figs, 5 plates, 4.…

Laminated leporello with 12 pp., gr. 8.

Ten flexible characters for two collections of a pulmonate land slug that differed in their method of preservation (ethanol or freezer/ethanol), were measured four times ? twice with calipers and twice with a stage micrometer ? by two different people. Repeated measurements were used to estimate the measurement error (ME) associated with the ten characters. ME ranged from 2% to 90% and differed significantly between the characters. Characters with low mean values and a high flexibility showed the largest ME. With the stage micrometer, one measurer obtained significantly higher ME, but both measurers obtained the same ME with calipers. There was no detectable effect of preservation method on the size and shape of characters, yet, results differed when characters were measured with either calipers or a stage micrometer. One measurer obtained significantly larger mean values for three characters with calipers. Additionally, presumed species differences between three Carinarion species (Arion fasciatus, A. silvaticus and A. circumscriptus; subgenus Carinarion Hesse 1926) were tested using principal component analysis and canonical discriminant analysis. Despite possible measurer biases and high ME, the different datasets yielded highly similar results, indicating that biometrical data of soft, flexible structures may yield valuable and reliable data which can be examined statistically. Our results indicate that A. fasciatus is larger than the other two species, but it is hard to distinguish from both of the other species when size is not considered. Arion silvaticus and A. circumscriptus can be separated only when colour characters are used. 10 pp., 2 figs, 4.…

In the past, 18S rRNA sequences have proved to be very useful for tracing ancient divergences but were rarely used for resolving more recent ones. Moreover, it was suggested that the molecule does not contain useful information to resolve divergences which took place during less than 40 Myr. The present paper takes littorinid phylogeny as a case study to reevaluate the utility of the molecule for resolving recent divergences. Two data sets for nine species of the snail family Littorinidae were analyzed, both separately and combined. One data set comprised 7 new complete 18S rRNA sequences aligned with 2 published littorinid sequences; the other comprised 12 morphological, 1 biochemical, and 2 18S rRNA secondary structure characters. On the basis of its ability to confirm generally accepted relationships and the congruence of results derived from the different data sets, it is concluded that 18S rRNA sequences do contain information to resolve rapid cladogenetic events, provided that they occurred in the not too distant past. 18S rRNA sequences yielded support for (1) the branching order (L. littorea, (L. obtusata, (L. saxatilis, L. compressa))) and (2) the basal position of L. striata in the Littorina clade. 11 pp., 5 figs, 4.…

7 pp., 3 figs, gr. 8.

Habitat fragmentation is a major cause for species loss, but its effect on invertebrates with low active dispersal power, like terrestrial gastropods, has rarely been studied. Such species can not cross a hostile habitat matrix, for which the predictions of island theory, such as positive relations between species richness and patch size, should apply. In order to test this prediction, we studied gastropod species diversity by assessing gastropod assemblage characteristics from 35 sites in 19 fragments of deciduous old-growth forests in the Lower Rhine Embayment, Germany. Assemblages differed between larger (?700 ha) and smaller forests (1,000 ha, i.e., well above the size of most fragments. In conclusion, the prediction is valid only for forest species. The response to fragmentation is species specific and seems to depend on habitat specialization and macroclimatic conditions. 13 pp., 4 figs, gr. 8.…

8 pp., 3 figs, 4.

Digestive gland esterases and albumen gland proteins of Arion (Carinarion) fasciatus, A. (C.) circumscriptus, A. (C.) silvaticus, A. (Kobeltia) hortensis, A. (K.) distinctus and A. (K.) intermedius were studied using vertical polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing (IEF). Each of the three Carinarion forms revealed characteristic and nearly monomorphic electrophoretic profiles. Yet some variation was also observed. Within each form the mean intraspecific similarities, calculated from IEF profiles, were high in comparison with similar figures for A. hortensis and A. distinctus. The interspecific similarities, however, were low and of about the same magnitude as those of the Kobeltia species. These results are discussed in the light of the reproductive biology of the Carinarion spp. It seems convenient to retain the three names A. fasciatus, A. circumscriptus and A. silvaticus, even though these do not necessarily refer to actual biological species. 14 pp., 10 figs, 4. …

20 pp., 5 figs, 4.

The taxonomy of the speciose genus Ganesella W.T. Blanford, 1863 and the endemic genus Globotrochus Haas, 1935 is unclear since the anatomical characters of the the type species of these two genera have never been reported before. Therefore, the present paper provides the first anatomical descriptions of the reproductive apparatus, pallial system and radula of Helix capitium Benson, 1848 and Helix onestera Mabille, 1887, the respective type species of Ganesella and Globotrochus. In addition, Ganesella rhombostoma (Pfeiffer, 1861) and Ganesella carinella (M?llendorff, 1902) from Thailand are re-described, and a new species, Ganesella halabalah Sutcharit & Panha, sp. nov., from southern Thailand is described. This new species differs from all others by having a larger shell, an obtuse apex and an aperture lip with a prominent beak-like deflection. New taxon: Ganesella halabalah n. sp. pp. 51-76, 8 figs, gr. 8.…

Eleven species of Glessulinae belonging to the genera Glessula Martens, 1860 (three species) and Rishetia Godwin-Austen, 1920 (eight species) are reported from Nepal, six of which are new to science and are described here, viz., G. tamakoshi Budha & Backeljau, sp. n., R. kathmandica Budha & Backeljau, sp. n., R. nagarjunensis Budha & Naggs, sp. n., R. rishikeshi Budha & Naggs, sp. n., R. subulata Budha & Naggs and R. tribhuvana Budha, sp. n. and two are new records for Nepal viz. G. cf. hebetata and R. cf. mastersi. The relation between the shell height-width ratio and the structure of the proximal part of the male reproductive organs in Glessulinae is explored. Illustrations and a key for the identification of the Nepalese Glessulinae are provided, including the first record of a spermatophore in Rishetia. New taxa: Glessula tamakoshi n. sp. n., Rishetia kathmandica n. sp., Rishetia nagarjunensis n. sp., Rishetia rishikeshi n. sp., Rishetia subulata n. sp., Rishetia tribhuvana n. sp. 28 pp., 14 figs, gr. 8. …

28 pp., figs., 4.

106 pp., br. 4.

This is the very first checklist of the terrestrial gastropods of Nepal. It includes 138 species and six subspecies, of which 22 species are endemic and four are introduced. It highlights 34 species recorded for the first time in Nepal and provides new distribution records for another 30 species. 48 pp., gr. 8.…

All known taxa of the genus Endothyrella Zilch, 1960 (family Plectopylidae) are reviewed. Altogether 23 Endothyrella species are recognized. All species are illustrated and whenever possible, photographs of the available type specimens are provided. Five new species are described: E. angulata Budha & P?ll-Gergely, sp. n., E. dolakhaensis Budha & P?ll-Gergely, sp. n. and E. nepalica Budha & P?ll-Gergely, sp. n. from Nepal, E. robustistriata P?ll-Gergely, sp. n. from the Naga Hills, India, and E. inexpectata P?ll-Gergely, sp. n. from Sichuan, China. Helix (Plectopylis) munipurensis Godwin-Austen, 1875 is synonymized with Helix (Plectopylis) serica Godwin-Austen, 1875, and Plectopylis (Endothyra) gregorsoni Gude, 1915 is synonymized with Helix (Plectopylis) macromphalus W. Blanford, 1870. Plectopylis plectostoma var. exerta Gude, 1901 is a synonym of Plectopylis plectostoma var. tricarinata Gude, 1896, which is a species in its own right. Five species of the genus Chersaecia viz. Plectopylis (Chersaecia) bedfordi Gude, 1915, Helix (Plectopylis) brahma Godwin-Austen, 1879, Helix (Plectopylis) Oglei Godwin-Austen, 1879, Helix (Plectopylis) serica Godwin-Austen, 1875, and Plectopylis (Endothyra) williamsoni Gude, 1915 are moved to Endothyrella. The holotype of Plectopylis hanleyi Godwin-Austen, 1879 seems to be lost; therefore, P. hanleyi is considered to be a nomen dubium. 70 pp., 26 figs, gr. 8.…