495 RESEARCH NOTES at extremely high densities of the larger species, D, REFERENCES serra. Moreover, D. serra is more sensitive to this than the smaller D. sordidus. These high densities of 1. MCLACHLAN, A., JARAMILLO, E., DONN, T.E. & D. serra, 4 0 - 6 0 clams per 0.1 m2 cylinder (or 4 0 0 - 6 0 0 WESSELS, F. 1993. / . Coastal Res., SI15: 27-38. m~2), match and exceed the maximum densities 2. DUGAN, J.E., HUBBARD, D.M. & PAGE, H.M. recorded in samples in nature10. This suggests that 1995. / . Coastal Res., 11: 849-857. only in exceptionally dense beds of adult D. serra . 3. JARAMILLO, E. & MCLACHLAN, A. 1993. Est. would intra- or interspecific effects, such as shown in Coastal Shelf Sci., 37: 615-624. these treatments, be encountered. The reason for D. 4. BRUCE, N.L. & SOARES, A.G. 1996. Cah. Biol. serra exhibiting this effect rather than D. sordidus is Mar., 37: 77-98. presumably size: its larger size makes it more likely 5. DEFEO, O . & D E ALAVA, A. 1995. Mar. Ecol. to encounter another clam when burrowing and less Progr. Ser., 123: 73-82. likely to fit into the interstices between buried clams. 6. ZAR, J.H. 1984. Biostatistical analysis. PrenticeMuch attention in benthic ecology has focussed on Hall, New Jersey. biological interactions between macrofauna. This has 7. MCLACHLAN, A., JARAMILLO, E., DEFEO, O., generally been investigated by enclosure/exclosure DUGAN, J., D E RUYCK, A. & COETZEE, P. 1995. experiments'1,12. Such techniques are not possible on Adaptations of bivalves to different beach types. high energy beaches such as that near the Maitland J. Exp. Mar. Biol. Ecol., 187:147-160. River. The value of this experiment is that it offers 8. MCLACHLAN, A. & YOUNG, N. 1982. Effects of a simple and workable alternative to enclosure/ low temperature on the burrowing rates of four exclosure experiments in exposed sandy beach ensandy beach mollusks. J. of Exp. Mar. Biol, and vironments. While it provides only a snapshot picture Ecol., 65: 275-284. of one response to interactions, it nevertheless gives 9. NEL, P. 1995. The effect of sand particle size on an idea of the threshold densities required for incipisandy beach macrofauna. MSc. thesis. University ent interference competition in mobile populations of Port Elizabeth. in a dynamic environment. 10. SCHOEMAN, D.S. 1997. Spatial and temporal The following are thanked for assistance: D. Flegg, dynamics of Donax serra in St. Francis Bay: A. Gaylard, P. Nel, A. Bentley, J. Heymans, B. implications for a potential fishery. PhD. thesis, Harwood, R. Sims, M. Moffett, H. McLachlan, K. University of Port Elizabeth, South Africa. McLachlan, F. McLachlan, A. McLachlan, S. Hosk- 11. REISE, K. 1985. Tidal flat ecology: an experimening, B. Ellior. Funding from the FRD (South Africa) tal approach to species interactions. Springerand University of Port Elizabeth is gratefully Verlag, Berlin. acknowledged. C.H. (Pete) Peterson, UNC, R. 12. PETERSON, C.H. 1991. Intertidal zonation of Victor, D. Clayton and two referees provided useful marine invertebrates in sand and mud. Amer. Sci., ideas and comments. 79: 236-249.
J. Moll. Stud. (1998), 64,495-499
© The Malacological Society of London 1998
First record of Deroceras juranumoutside the Jura mountains (Pulmonata: Agriolimacidae) Kurt Jordaens1, Thierry Backeljau2, Heike Reise3, Patrick Van Riel2 and Ron Verhagen1
'University of Antwerp (RUCA), Department of Biology, Groenenborgerlaan 171, B-2020 Antwerp, Belgium; e-mail:
[email protected] 2Royal Belgian Institute of Natural Sciences, Vautierstaat 29, B-1000 Brussels, Belgium 3Staatliches Museum fur Naturkunde Gorlitz, PF 30 01 54, D-02806 Gorlitz, Germany Deroceras juranum Wiithrich, 1993 is a terrestrial agriolimacid slug that has been described as a new endemic species from altitudes above 900 m in a restricted area in the Swiss Jura (NW Switzerland, Fig. I) 1 , The species has a flat and wide stimulator inside the penis and is therefore assigned to the subgenus Plathystimulus Wiktor, 1973. In general, D. juranum appears to be very similar to D. (P.) rodnae Grossu & Lupu, 1965, except for the body colour, which is light cream in D. rodnae but dark violet in
D. juranum. However, recent breeding experiments have shown convincingly that D. juranum and D. rodnae freely hybridize and that their body colour behaves as a Mendelian trait coded by a single locus with two alleles, with 'violet' dominant over 'cream'2. These experiments also showed that both species are indistinguishable with respect to their mating behaviour, even though this is usually a highly speciesspecific character by which very similar Deroceras species can be separated3. It also appeared that
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Figure 2. Penis anatomy of D. rodnae and D. juranum: 2A. D. rodnae from Austria; 2B. D. juranum from Austria; 2C. D. rodnae from Switzerland (Weissenstein, Dilitschkopf, coll. by H. Reise in 1994); 2D. D. juranum from Switzerland (Chasseral, coll. by H. Reise in 1994); 2E, D. rodnae from Switzerland (Hasenmatt, coll. by H. Reise in 1994) and 2F. D. juranum from Switzerland (offspring of a slug from Hasenmatt, coll. by H. Reise in 1994). Scale bar: 1 mm. A - atrium, Ov - oviduct, Pd - distal penis part, Pg - penial gland, Pp - proximal penis part, R - penis retractor, Vd - vas deferens.
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Figure 3. Stimulator of D. rodnae and D. juranum: 2A. D. rodnae from Austria; 2B. D. juranum from Austria; 2C. D. rodnae from Switzerland (St. Brais, near Glovelier, coll. by Clerx in 1971); 2D. D. juranum from Switzerland (Chasseral, coll. by Dufour in 1979); 2E. D. rodnae from Switzerland (Gals, coll. by Dufour in 1981) and 2F. D. rodnae from Switzerland (Hasenmatt, coll. by H. Reise in 1994). Scale bar: 1 mm.
RESEARCH NOTES 499 anatomically, D. juranum and D. rodnae show no morph of D. rodnae. This implies that D. juranum is consistent differences.2 Finally, a preliminary elec- not endemic to the Swiss Jura and may be much trophoretic comparison of 16 allozyme loci provided more widely distributed than has previously been no indication of a specific differentation between D. assumed. It also suggests that D. juranum is not jaranum and D. rodnae*. These observations strongly restricted to altitudes above 900 m. Therefore, it suggested that D. juranum is merely a violet colour remains speculative to correlate the violet colour morph of D. rodnae. Nevertheless, for the time being with differential selective regimes imposed by lower we will continue to apply the name D. juranum to temperatures and lower oxygen pressures at higher altitudes (see7-8-'). the violet colour morph The fact that D. juranum is not recognized as a Here we report the finding of four adult D. juranum individuals from NE Austria (Steinegg, separate species does not affect its relevance for con48°38'N;,15°34'E) on 26/4/1997 (Fig. 1). This appears servation issues. Indeed, the IUCN also recognizes to be the first record of D. juranum outside the Jura intraspecific genetic variation as a level requiring mountains (± 590 km more to the east), at a locality conservation10. In this context D. juranum apparently where the malacofauna has already been well-stud- represents a rare allele with a limited, fragmented (?) ied5'6. The D. juranum individuals were collected in a distribution compared to the total area inhabited by beech forest near the river Kamp (altitude: ± 300 m). cream-coloured D. rodnae. It therefore seems wise to The area has been described in detail earlier56. At monitor the distribution of D. juranum in order to the same spot, we also collected 10 cream-coloured confirm or extend the current pattern, particularly in Deroceras specimens. All animals were brought alive Austria where the present record involves a strongly to the laboratory where they were killed by freezing isolated, unique peripheral population that may have at —80°C. Later, the animals were stored at 70% to be included in the list of threatened species. We ethanol. Unfortunately, one of the violet individuals consider that the distribution of this species is still dried out and was unsuitable for further analysis. All too poorly documented, so for the time being we the other animals were dissected to examine their intend including it in the list of 'data deficient genital apparatus and their genital morphology was species'11. compared with that of D. juranum and D. rodnae We are indebted to H. Van Paesschen for the artfrom the Swiss Jura mountains. The genitalia of work. This study was supported by F.J.B.R. grant violet and cream slugs did not differ within popula- 2.0128.94. tions (Fig. 2A,B for Austrian animals and 2C,D for Swiss animals), but we observed three minor differences between Swiss and Austrian D. rodnae! REFERENCES juranum populations viz. 1) Austrian specimens have a rather short and wide stimulator (Fig. 3A,B) while WUTHRICH, M . 1993. Arch. Moll., 122:123-131. in Swiss specimens it is more slender (Fig. 3C,D), 2.1. REISE, H . 1997. /. Zool, Lond., 241:103-115. although animals from Eastern Europe may have a 3. REISE, H. 1995. /. Moll. Stud., 61:325-330. short and wide stimulator, too (Reise, unpublished H . 1996. BCPC Symp. Proc: 315. results), 2) the penis retractor is usually very strong 4.5. REISE, REISCHUTZ, P. 1984. Heldia, 1: 29-32. and short in Swiss specimens (Fig. 2C,D), but in C. 1987. Unsere Heimat, 58: 214-221. Austrian animals it is rather long and thin (Fig. 2B) 7.6. FRANK, CLARKE, B., ARTHUR, W., HORSLEY, D.T. & and 3) a low fold within the penis connecting the real PARKIN, D.T. 1978. In: Pulmonates 2A, systemstimulator with an (always present) rather large fold atics, evolution and ecology (Fretter, V. & 1 named by Wuthrich as 'secondary stimulator' which Peake, J. Eds.), London, New York, San Franis usually present in Swiss slugs (Fig. 3C,D) but is cisco: Academic Press. lacking in the Austrian specimens (Fig. 3A,B). How8. ALBONICO, R. 1948. Rev. Suisse Zool., 55: 347¬ ever, in general, D.rodnae is quite variable in penis 425. morphology and some D. rodnae from Switzerland CHEVALLIER, H . 1977. Haliotis, 6: 41-48. do have a long, thin penis retractor (see e.g. Fig. 3c 10.9. MCNEELY, J.A., MILLER, K.E., REID, W.V., MITin2 and Fig. 2E,F) as well as a stimulator which is not TERMEIER, R.A. & WERNER, T.B. 1990. Conconnected to the little 'second' stimulator (Fig. serving the world's biological diversity, IUCN, 3E,F). Therefore, we consider this variation as intraGland. specific and we conclude that the violet Austrian 11. IUCN RED LIST CATEGORIES, 1994. specimens are conspecific with D. juranum from the HTTP://WWW.WCMC.ORG.UK/SPECIES/ANIMALS/CAT Swiss Jura and thus represent the violet colour EGORIES.HTML.
