Wallaconchis achleitneri Goulding

Goulding, Tricia C., Khalil, Munawar, Tan, Shau Hwai & Dayrat, Benoit, 2018, Integrative taxonomy of a new and highly-diverse genus of onchidiid slugs from the Coral Triangle (Gastropoda, Pulmonata, Onchidiidae), ZooKeys 763, pp. 1-111 : 1

Wallaconchis achleitneri Goulding sp. n. Figs 50, 51, 52, 53

Type locality.

Australia, Queensland, Bowen, Doughty Creek, 20°01.26'S, 148°14.35'E, st 117, Avicennia and Rhizophora trees by a creek with sandy mud.

Type material.

Holotype, 7/5 mm [3534], designated here (st 117, MTQ).

Additional material examined.

Australia, Queensland, Bowen, Doughty Creek, 20°01.26'S, 148°14.35'E, 64 specimens 16/10 mm [#3] to 8/5 mm [3535]; 14/8 mm [#1], 14/8 mm [#2], 14/8 mm [#4] and 9/6 mm [2645], st 117, Avicennia and Rhizophora trees by a creek with sandy mud (st 117, MTQ).

Distribution.

Australia: Queensland (type locality).

Habitat

(Fig. 50 A–B, Table 3). Animals were found abundantly in a small mangrove patch near a small river, on mud with large grain sand. Wallaconchis achleitneri was found at only one station in Queensland despite five weeks of sampling, suggesting it may require something particular in this habitat, possibly the sediment.

Etymology.

Wallaconchis achleitneri is dedicated to Stefan Achleitner, a team member in our expedition to Queensland, and whose German translation helped to clarify parts of old and challenging species descriptions.

Diagnosis

(Table 5). Externally, Wallaconchis achleitneri cannot be distinguished from brown or grey specimens of other Wallaconchis species, except by its small size. Internally, the combination of a smooth, long, and narrow penis within a large penial vestibule, a spherical spermatheca, a free (not attached to the body wall by fibers), and a slightly enlarged oviduct distinguishes W. achleitneri from other Wallaconchis species. Finally, even though its known species distribution may change in the future, W. achleitneri is not presently considered to be sympatric with any other Wallaconchis species.

Color and morphology of live animals

(Fig. 50 C–E). The dorsal notum is brownish grey. The ocular tentacles are orange-brown. The hyponotum and foot are yellow-grey.

External morphology.

The number of dorsal papillae with eyes is three to four papillae with three to four eyes per papilla. There is a retractable papilla with three to four eyes in the center of the dorsal notum, but which is not raised above the other papillae.

Digestive system

(Fig. 51, Table 4). Examples of radular formulae are presented in Table 4. The length of the rachidian teeth is approximately 15 µm, significantly smaller than that of the lateral teeth. The length of the hook of the lateral teeth gradually increases (from 30 to 35 µm) from the inner to the outer teeth (excluding the innermost and outermost lateral teeth which are significantly smaller). The intestinal loops are of type I.

Reproductive system

(Fig. 52A). In the posterior (hermaphroditic) part of the reproductive system, the oviduct is larger in circumference than the deferent duct. The spherical spermatheca joins the distal region of the oviduct through a short duct.

Copulatory apparatus

(Figs 52B, 53). The penis (approximately 0.6-0.9 mm long) is narrow and smooth with no hooks (Fig. 53). The penial vestibule is cylindrical and the penial sheath is narrow. The distal end of the penis lies within the vestibule (Fig. 52B). The distal end of the deferent duct is approximately the same width as the penial sheath. The deferent duct is convoluted. The retractor muscle is slightly longer than the penial sheath and inserts at the posterior end of the body cavity, near the rectum.