Mating of Xerolenta obvia

Xerolenta obvia is a hygromiid land snail. As its distribution area is referred Pontic region, but it occurs from Asia Minor to the Baltic Sea and to eastern France.


It lives in open dry grassy habitats. It is xerophilic (drought-resistant) and thermophilic species (lives in relatively high temperatures). This species hibernates in winter and it aestivates during summer for few months.


Aestivating Xerolenta obvia:


A group of aestivating Xerolenta obvia:


Epiphragm of Xerolenta obvia:


It is a hermaphrodite land snail. It means, that one snail specimen has both sexes. Snails tranfer its sperm during mating. Later cross-fertilization occur. After some time later it lays separated 7-95 uncalcified eggs in a single clutch.


They reach sexual maturity in one year or later. For example in one area in Greece they reach maturity in 8 months after egg was layed (7 months after hatching), but they die after egg laying in the age about 1 year. In another area of Greece they reach sexual maturity in 1.5 years after egg was layed (= 18 months) and they have lived 2 years. Other source refer to longevity 2-3 years.


In Mediterranean they are mating and egg laying in autumn only. In Central Europe they are mating and egg laying from late spring to to early summer. It is mating in October (in Greece) after the aestivation in only few days.


I have found photos of mating of this species neither in the literature nor on the internet. I have taken 5 snails from the locality shown above to home at 3rd August 2011 and the later day I have recored the mating of them. Photos are in chronological order, but they are showing the same position all the time:


4th August 2011 06:25






Video of mating of Xerolenta obvia (30 seconds at 06:32):





Video of the last six minutes of mating:



Irikov A. & Mollov I. (2006). Terrestrial gastropods (Mollusca: Gastropoda) of the western Rhodopes (Bulgaria). pp. 753-832. In: Beron P.: Biodiversity of Bulgaria. 3. Biodiversity of western Rhodopes (Bulgaria and Greece) I.


Falkner G., Obrdlík P., Castella E. & Speight M. C. D. (2001). Shelled Gastropoda of Western Europe. München: Friedrich-Held-Gesellschaft, 267 pp.


Lazaridou M. & Chatziioannou M. (2005). Differences in the life histories of Xerolenta obvia (Menke, 1828) (Hygromiidae) in a coastal and a mountainous area of northern Greece. Journal of Molluscan Studies 71(3): 247-252. doi:10.1093/mollus/eyi032 abstract


(in Slovak) Lisický M. J. (1991). Mollusca Slovenska [The Slovak molluscs]. VEDA vydavateľstvo Slovenskej akadémie vied, Bratislava, 344 pp.


Species summary for Xerolenta obvia“. AnimalBase, last modified 22 March 2011, accessed 5 December 2011.

Photo of the day (6): Arion vulgaris – mating and ovotestis

Arion vulgaris is a serious agricultural pest in Europe. It is a hermaphroditic slug. They have gonad in male phase before and during mating. During the mating they “think”, that the other slug is female and they will exchange sperm reciprocally. Later, some time after mating, they will get to female phase, they will produce ova and they will use received and stored sperm to fertilize its ova.


That is not in ideal circle on the photo, because I have disturbed them to move them into glass to take photos.


Reproductive system is usually important in determination of species. There were usually black and white drawings of reproductive system of gastropods in scientific literature. Only sometimes there are photos of reproductive system in newer publications. I found no photos of reproductive system of Arion species on the internet.


End of visceral mass removed from tail end on the body of the slug. There are not parts, that could be useful in species identification in this photo. It shows hepatopancreas and ovotestis. The hepatopancreas is that brown mass. Maybe it shows the whole hepatopancreas, but I am not sure, because the whole part on the photo is roughly torned off the rest of the body. The grey part is ovotestis.


The most important part of the reproductive system in hermaphroditic pulmonate slugs is ovotestis (= gonad, = hermaphordite gland). Ovotestis consist of some lobes. Each lobe consist of number of acini. The ovotestis of Arion vulgaris (as far as I can see) has five lobes. Ovotestis produces sperm (spermatogenesis) in male phase and it produces ova (ovogenesis) in female phase. I do not know in which phase the ovotestis is on the photo. I think that it should be possible to identify histologically, but I do not know, if it is possible to identify macroscopically. Spermatozoa grows in the inner part of each acinus. Oocytes grows in cortex of each acinus.