Nanotrachia, 2013

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 : 120-121

NANOTRACHIA COSTULATA COSTULATA SSP. NOV.

Holotype

Australia, WA, EK, 12.3 km east of Spring Creek Station Homestead , east of Duncan Highway, low exposed hills with limestone cliffs of 2–3 m in height, Spinifex , few fig trees, under slabs in loose soil, 16°59′57″S, 128°58′34″E (coll. V. Kessner, 30 August 2009); dissected specimen ( WAM S66302).

Paratypes

Same as holotype; 11 wet ( WAM S49191 ), 11 dry ( WAM S49073 ) .

Other material: Table 1.

Etymology

In reference to the shell sculpture of axial ribs, derived from ‘costulatus’ (Latin = exhibiting ribs), adjective of feminine gender.

Description

Shell ( Figs 4D , 5E, F ): Average in size; periphery shouldered, weakly keeled; spire weakly elevated; umbilicus open, wide, sometimes partly concealed by columellar reflection; protoconch and teleoconch with dense, pointed periostracal projections and fine axial growth lines; teleoconch with prominent, blunt, widely spaced axial ribs; apertural lip reflected, moderately expanded; horn.

Genitalia ( Fig. 7A, B ): Epiphallus long, thick, tapering in thickness, length equivalent to 50–70% of penis; thick muscular fibres connecting distal portion of epiphallus to penial apex. Vas deferens entering penial sheath almost halfway up. Inner penial wall with up to four, mostly narrow, nearly straight longitudinal pilasters comprising entire length of penial wall.

Vagina half as long as penis, half to twice as long as free oviduct.

Comparative remarks

Shell similar to N. intermedia both in size and shape, differing from N. carinata sp. nov., N. coronata sp. nov., and N. orientalis by less developed keel, and from N. levis sp. nov. by presence of axial ribs. Genitalia of N. carinata sp. nov., N. coronata sp. nov., and N. levis sp. nov. differ by having corrugated penial wall pilasters; N. intermedia has only one penial wall pilaster.

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 7. Intraspecific variation of penial anatomy in N. costulata sp. nov. A, Nanotrachia c. costulata (holotype WAM S66302); B, Nanotrachia c. costulata (WAM S49174); C, Nanotrachia c. montejinni ssp. nov. (holotype NTM P48939); D, Nanotrachia c. montejinni (AM C.437659). Insets showing schematic cross section of midpenis. Scale bar = 2 mm.