Arion vulgaris is an important pest in agriculture and it is quite a big slug. It can reach up to 12 cm. It is widely distributed through the Europe. I think, it could be more widely used as a model organism at least in education about basal anatomy of slugs. Despite that, I found no many photos of its anatomy. It is probably because of this species is not usually necessary to be dissected for identification. When some anatomy photos are available, then they are depicting only a part of the reproductive system dissected from the body of the slug and/or they are black-and-white only.
I have briefly dissected the slug: I have removed the body wall (with ovotestis (=glandula hemaphroditica) and with a part of hepatopancreas also accidentally removed) and I have kept the head undissected in detail. This specimen comes from Olomouc, the Czech Republic and I have collected and dissected it on the 11th August 2011.
There are visible the following structures of the reproductive system:
atrium. Atrium is short in comparison of Arion rufus.
oviductus. There should be a ligula within the oviductus that is an identification character of this species, but the ligula is not visible on the photo here, because I did not cut the wall of oviductus.
ductus hermaphroditicus (white thin meandering like tube)
glandula hemaphroditica and hepatopancreas. Part of hepatopancreas and probably the whole glandula hemaphroditica is accidentally removed from this dissected slug.
There is also visible tube like digestive system and glandulae mucosae:
oesophagus comes from the frontal part and is contected to the hepatopancreas
intestine comes from hepatancreas back to frontal part and it ends with anus, that is not visible here.
References and further reading:
(in Czech) Horsák M., Juřičková L., Beran L., Čejka T. & Dvořák L. 2010: Komentovaný seznam měkkýšů zjištěných ve volné přírodě České a Slovenské republiky. [Annotated list of mollusc species recorded outdoors in the Czech and Slovak Republics]. – Malacologica Bohemoslovaca, Suppl. 1: 1–37.
(in Russian) ГУРАЛЬ-СВЕРЛОВА Н. В. & ГУРАЛЬ Р. И. [Gural-Sverlova N. V. & Gural R. I.] 2011: Морфологические, анатомические и поведенческие особенности слизней из комплекса Arion lusitanicus (Arionidae) на западе Украины. [Morphological, anatomical and behavioural peculiarities of the slugs from the Arion lusitanicus complex in Western Ukraine]. – Ruthenica. 21(2): 97-111.
(in Polish) Riedel A. & Wiktor A. 1974: Arionacea. Ślimaki krążałkowate i ślinikowate: Gastropoda, Stylommatophora. Fauna Polski 2, Warszawa. 141 pp.