Strubellia paradoxa ( Strubell , 1892)

Brenzinger, B., Neusser, T. P., Glaubrecht, M., Haszprunar, G. & Schrödl, M., 2010, Redescription and three-dimensional reconstruction of the limnic acochlidian gastropod Strubellia paradoxa (Strubell, 1892) (Gastropoda: Euthyneura) from Ambon, Indonesia, Journal of Natural History 45 (3 - 4), pp. 183-209 : 201-202

Strubellia paradoxa ( Strubell, 1892)

Acochlidium paradoxum Strubell, 1892 : Verhandl. naturh. Verein preuss. Rheinlande,

48. Jahrg., Sitzung d. niederrhein. Ges. 13. Juni 1892: 62

Acochlidium paradoxum Küthe 1935 : Zool. Jahrb. Syst. 66: 513–540

Strubellia paradoxa Odhner 1937 : Zool. Anz. 120: 237–238

The bipartite copulatory apparatus and complex kidney identify S. paradoxa as a member of the hedylopsacean Acochlidia , ( Wawra 1987) whereas the limnic habitat separates it from the smaller but otherwise rather similar Pseudunela species. Strubellia paradoxa differs from the likewise limnic Acochlidium species in the following characters: a uniformly coloured body with an elongate visceral sac more or less round in cross-section, very slender median cusps of the rhachidian teeth, a copulatory apparatus with only a single penial spine and a stylet-bearing basal finger that is larger than the penis, and in being a sequential hermaphrodite (see Wawra 1988; Neusser and Schrödl 2009; Schrödl and Neusser 2010 for discussion).

Strubellia paradoxa differs from Strubellia “ paradoxa ” sensu Wawra (1974, 1988) from the Solomon Islands and, apparently, Vanuatu (mentioned in Haynes 2000; own unpublished data) in the length and form of the basal finger’s stylet: in S. paradoxa , the stylet is approximately 0.5–0.6 mm long [measured from Küthe (1935) and 3D reconstruction; see Figures 6C , 7E ], has a continuous curve and is rather stout compared with that of Strubellia from the Solomon islands. There, it is approximately 1 mm long, slender and has a hooked tip ( Wawra 1974: fig. 4).

We are currently processing specimens for DNA analysis to determine whether there are genetic differences between the Ambon, Solomon Islands and Vanuatu populations.

Figures

Figure 6. Schematic overview of the genital system, male phase. (A) Overview of posterior genital system of paratype, ∗ indicates genital pore, ∗∗ indicates widening in distal bursa stalk, dorsal view; (B) overview of cephalic copulatory apparatus of paratype, dorsal view; (C, D) adapted from Küthe (1935), used with permission: (C) copulatory apparatus with anterior muscle (showing external duct with distal bifurcation and bypass leading into lumen and groove of the stylet) and posterior muscle (with duct passing through the retractor muscle and exiting through a papilla close to a hooked thorn); (D) cross-section of stylet showing lumen and groove. Abbreviations: am, ampulla; bc, bursa copulatrix; bf, basal finger; bp, bypass of paraprostatic duct; bvd, “posterior-leading” vas deferens; dv, diverticle; ed, ejaculatory duct on raised papilla; gd, gonoduct; go, gonad; gr, groove of cuticular stylet; m1, “anterior” muscle, confused with the penis by Küthe; m2, “horseshoe-shaped posterior” muscle; p, penis; pp, paraprostate; ppd, paraprostatic duct; pr, prostate; ps, penial sheath; rm, retractor muscle of copulatory apparatus; rs, receptaculum seminis; sg, external sperm groove on right body side; st, hollow stylet; th, thorn.

Figure 7. Three-dimensional reconstruction of the genital system, male phase. (A) Genital system (right view); (B) posterior genital system (oblique anterior view); (C) detail of distal gonoduct and genital opening (right view); (D) complete genital system (ventral view); (E) copulatory apparatus (anteroventral view); (F) copulatory apparatus (right view, ∗ indicates blind ending of paraprostate; prostate and penial sheath omitted). Abbreviations: am, ampulla; bc, bursa copulatrix; bf, basal finger; bp, bypass of paraprostatic duct; bs, bursa stalk; bvd, “posterior-leading” vas deferens; dv, diverticle; ed, ejaculatory duct; gd, gonoduct; go, gonad; gol, central lumen of gonad; gp, genital pore; gpa, anterior genital opening; p, penis; pp, paraprostate; ppd, paraprostatic duct, pr, prostate; ps, penial sheath; rm, retractor muscle; rs, receptaculum seminis; sg, external sperm groove; st, stylet; th, thorn. Scale bars: A, 1 mm; B, D–F, 250 µm; C, 100 µm.