Arion VULGARIS
Creators: name: Reise, Heike
name: Schwarzer, Anne-Katrin
name: Hutchinson, John M. C.
name: Schlitt, Bettina
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Stylommatophora
Arionidae
Arion

description: <i>ARION VULGARIS</i> (Figs 2, 22–24, 40–42) (1) A t r i u m a n d d i l a t e d o v i d u c t (Figs 2, 40) The upper, muscular atrium is smaller and not nearly as swollen and muscular as in <i>A. ater</i> s.l. Instead, the distal genitalia are dominated by a strong dilated oviduct. The thin oviduct connecting proximally to this muscular part is similar to that in <i>A. ater</i> s.l. (though usually shorter). Instead of the strong atrium retractor of <i>A. rufus</i>, a strong retractor inserts onto the distal part of the dilated oviduct. (2) I n s e r t i o n o f d u c t s (Figs 23, 40) Epiphallus and bursa-duct enter the upper atrium proximally, inserting onto a lateral bulge of the atrium just beside the insertion of the dilated oviduct. In a specimen opened as described above, these insertions are thus visible, posterior to the oviduct insertion, without having to detach any genital retractor muscle (although in mature specimens, the bursa and/or the spermoviduct may have to be pushed aside). In contrast to the triangular arrangement in <i>A. rufus</i>, the insertions of oviduct, epiphallus, and bursa-duct lie roughly along a straight line (in that order). (3) L i g u l a (Figs 2, 22–24, 41) The ligula is in the dilated oviduct. If the slug has been opened as described above, and no genital retractor cut, before we open the oviduct the ligula base is on the wall of the oviduct lying upwards, away from the body wall. A cut along the oviduct in line with the retractor muscle allows one to turn over the ligula (Figs 2, 41), which should then be fully visible and undamaged. The ligula is not bent and folded up as in <i>A. ater</i> s.l. but extended along the length of one side of the dilated oviduct; in comparison with <i>A. ater</i> s.l., one flank of the base is missing. The insertion of the thin oviduct is at the proximal end of the ligula base. The ligula takes the shape of a long boat with the ligula base corresponding to the bottom of the boat, the flange its sides. and the bow pointing towards the atrium (DAVIES 1987). Our illustrations (Figs 24, 41) show the distal end of the oviduct orientated downwards (Figs 24, 41), so we will refer to the flange on the left side of the boat as the right flange (we imply no homology with the left and right flank in <i>A. ater</i> s.l.). The width of the flange is asymmetric, though much less so than in <i>A. ater</i> s.l., and it is also generally narrower and varies less between specimens. The right flange is thicker and stronger than the left but forms only a bulge rather than the prominent flap in <i>A. ater</i> s.l. At the proximal end (the stern of the boat), the flange running closely around the opening of the thin oviduct is very narrow. The opening of the thin oviduct is directly underneath its insertion: there is no tunnel running through the ligula base. The most prominent ligula structure is the bow of the boat, where both longitudinal folds meet distally and project as a thick tongue into the atrium (Fig. 41); this tongue is attached only within the dilated oviduct. In a few individuals, a small single or double fold extends along the base, reminiscent of the two folds flanking the funnel-like structure on the right flank of the ligula in typical FR and BR. (4) Posterior lip and associated ridge (Figs 22, 23, 41) A ridge, generally less prominent in <i>A. vulgaris</i> than in <i>A. ater</i> s.l., leads to the opening of the bursa-duct, where it expands and forms a loop. This creates the spoon-shaped structure that ALLGAIER (2014) referred to as the posterior lip. The other end of the spoon continues as a small longitudinal fold towards the lower atrium. (5) E p i p h a l l u s (Fig. 42) The inner wall of the distal epiphallus contains longitudinal rows of big tubercles which are usually arranged in 5–6 well-ordered rows. Sometimes there are only 2 or 3 rows of big tubercles, and in this case there may be a few additional rows of smaller tubercles.
description: Published as part of <i>Reise, Heike, Schwarzer, Anne-Katrin, Hutchinson, John M. C. &amp; Schlitt, Bettina, 2020, Genital morphology differentiates three subspecies of the terrestrial slug Arion ater (Linnæus, 1758) s. l. and reveals a continuum of intermediates with the invasive A. vulgaris Moquin-Tandon, 1855, pp. 1-34 in Folia Malacologica 28 (1)</i> on pages 16-17, DOI: 10.12657/folmal.028.001, http://zenodo.org/record/4615365
description: {"references": ["DAVIES S. M. 1987. Arion flagellus Collinge and A. lusitanicus Mabille in the British Isles: a morphological, biological and taxonomic investigation. Journal of Conchology 32: 339 - 354.", "ALLGAIER C. 2014. How can two soft bodied animals be precisely connected? A miniature quick-connect system in the slugs, Arion lusitanicus and Arion rufus. Journal of Morphology 276: 631 - 648. https: // doi. org / 10.1002 / jmor. 20361"]}