Diagnosis
Shell subglobose, 19.6-25.2 mm in height and 25.6-32.1 mm in width, dark brown to black (typical) or pale yellow; red umbilical patch and subsutural band absent; inner lip pale pink to mauve lip. Mantle reddish orange. Penis long but shorter relative to length of long vagina.
Description
Shell : Subglobose, 19.6-25.2 mm in height, 25.6-32.1 mm in width. Spire moderately elevated. Aperture roundly ovate, height 13.8-16.7 mm, width 16.5-20.8 mm. Total number of whorls 5.4-6.0. Last teleoconch whorl rounded; height 17.2-21.1 mm. Teleoconch sculpture of growth lines. Teleoconch periostracal sculpture of weak zigzag ridges, with minor sculpture between major ridges. Protoconch sculpture weakly pustulose. Shell uniform dark brown to black, occasionally pale yellow, with red umbilical patch, subsutural line and supraperipheral band absent. Inner lip pale pink to pale mauve, strongly reflected and largely obscuring umbilical depression. Outer lip moderately deflected below midline of last whorl. Umbilicus closed. Dimensions of syntypes of Helix gulosa: (MCZ, 3) SH—21.4-23.0 mm, SW—27.5-30.7 mm, AH—15.5-16.0 mm, AW—18.7-20.1 mm, BW— 18.2-21.3 mm, TW—5.25-5.60 whorls.Non-genital Anatomy. Animal colour orange-red, mantle reddish orange. Kidney approximately 50-59% of length of mantle roof.

It is not clear exactly where in the Illawarra region (an area encompassing the Illawarra Coastal Plain, S. of Sydney and bounded by the Illawarra Escarpment in the west and stretching from Stanwell Park in the north to the Shoalhaven River in the south, about 75 km) the types of Helix gulosa might have been collected, but there were a number of roads in the general area in the 1840s. It is possible that the material came from the Mt Keira area because the Ford family (who helped obtain material for the US Exploring Expedition, 1838-1842) had a property in the area. Nanina fricta Gould, 1852 [= Austrorhytida capillacea (Ferussac, 1832), Rhytididae], was collected at the same time. However, this species is often found with M. gulosum throughout its range and unfortunately does not help to narrow down the area where the original specimens were collected. Over the last 160 years, the native vegetation of the Illawarra area has been largely cleared for agriculture, urban and industrial development. There are still some small remnants of dry rainforest located in the Berkeley area and the upper slopes of Mt Nebo and Mt Keira (Mills and Jakeman 1995), which contain populations of snails similar to the type specimens.
The relatively large shell of M. gulosum is uniformly coloured dark or pale brown or black, with no red umbilical patch or subsutural band and is thus readily distinguished from other species of Meridolum. The rounded periphery of the body whorl distinguishes M. gulosum from similar unicoloured species of Pommerhelix n. gen. such as P. monacha (Pfeiffer, 1859) and P. mastersi (Cox, 1864), which have an angled to keeled periphery.
Based on anatomical and morphological characters and preliminary allozyme and 16S mitochondrial DNA data (Clark 2005), it is apparent that many of the populations formerly classified as M. gulosum almost certainly represent additional unrecognised narrow-range taxa. However, no additional taxa are recognised presently as this was beyond the scope of this project. Therefore, as further surveys and detailed studies are conducted additional species will be recognised from the Illawarra area from about Otford south to the Shoalhaven River.

Meridolum gulosum is restricted to the rainforests and vine thickets of the Illawarra Escarpment south of Sydney, ranging from Bulli Pass south to about Wollongong. Meridolum gulosum is found under fallen palm fronds, wood, bark and other debris and in leaf litter.