Nanotrachia undetermined

Köhler, Frank & Criscione, Francesco, 2013, Small snails in a big place: a radiation in the semi-arid rangelands in northern Australia (Eupulmonata, Camaenidae, Nanotrachia gen. nov.), Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 169 (1), pp. 103-123 : 119-120

NANOTRACHIA CARINATA SP. NOV.

Holotype

Australia, WA, EK, 40.6 km north-west of Nicholson Station Homestead , limestone area with numerous gullies, base of cliffs, Spinifex , and talus, under rocks in loose soil, 17°49′30″S, 128°34′40″E (coll. V. Kessner, 1 September 2009); dissected specimen ( WAM S66300 ).

Paratypes

Same data as holotype; two wet ( WAM S49178 ), 85 dry ( WAM S49100 ) .

Etymology

In reference to the peripheral keel of the shell, derived from ‘carinatus’ (Latin = possessing a keel), adjective of feminine gender.

Description

Shell ( Figs 4B , 5A, B ): Average in size; periphery shouldered, strongly keeled; spire weakly elevated; umbilicus open, wide, not concealed by columellar reflection; protoconch and teleoconch with dense, pointed periostracal projections and fine axial growth lines; teleoconch with weak, blunt, narrowly spaced axial ribs, interrupted on keel; apertural lip reflected, moderately expanded; yellowish–horn.

Genitalia ( Fig. 6C ): Epiphallus very short, onequarter of penial length; no muscle fibres connect the epiphallus and penial apex. Vas deferens entering penial sheath almost halfway up. Penial wall thin, with two longitudinal pilasters, one wide, irregular, comprising half of penial wall, second pilaster thinner, irregularly shaped, winding, with regularly spaced, pointed corrugations; penial pore surrounded by subcircular ridge. Vagina slightly shorter than penis, half to twice as long as free oviduct.

Comparative remarks

Shell similar to N. coronata sp. nov., but smaller in size, axial ribs interrupted on keel. Differs from N. levis sp. nov. by presence of keel, from all other congeners by less developed axial ribs. The largest shells of N. carinata sp. nov. are similar to the smallest shells of O. elegans , which differ by more elevated spire and weaker developed periostracal projections. Genitalia identical to N. coronata sp. nov., N. levis sp. nov. has three pilasters, and all other species have smooth pilasters.

Figures

Figure 4. Shells of Nanotrachia species studied herein. A, N. intermedia (Solem, 1984) (paratype AM C.146110); B, Nanotrachia carinata sp. nov. (paratype WAM S49100); C, N. coronata sp. nov. (paratype WAM S49086); D, N. costulata costulata sp. nov. (WAM S49088); E, N. levis sp. nov. (paratype WAM S49096); F, N. orientalis (Solem, 1984) (paratype AM C.146105); G, Mouldingia occidentalis (Solem, 1984) (paratype AM C.146107). Scale bar = 1 cm.

Figure 5. SEM micrographs of shells showing protoconch and teleoconch microsculpture. A–B, N. carinata sp. nov. (paratype WAM S49100); C–D, N. coronata sp. nov. (paratype WAM S49086); E–F, Nanotrachia costulata sp. nov. (WAM S49088); G–H, N. levis sp. nov. (paratype WAM S49096). Scale bars: A, C, E, G = 1 mm; B, D, F, H = 200 Mm.

Figure 6. Penial anatomy. A, Nanotrachia intermedia (Solem, 1984) (WAM S49195); B, N. intermedia (Solem, 1984) (WAM S49194); C, Nanotrachia carinata sp. nov. (holotype WAM S66300); D, N. levis sp. nov. (holotype WAM S6630). Insets showing schematic cross section of mid-penis. Scale bar = 2 mm.