Exiligada unistriata, Criscione & Law & Köhler, 2012

Criscione, Francesco, Law, Margot Louisa & Köhler, Frank, 2012, Land snail diversity in the monsoon tropics of Northern Australia: revision of the genus Exiligada Iredale, 1939 (Mollusca: Pulmonata: Camaenidae), with description of 13 new species, Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 166 (4), pp. 689-722 : 713-715

EXILIGADA UNISTRIATA SP. NOV.

( FIGS 4G , 6G , 26 , 27 )

Holotype: AUSTRALIA, NT, VRD, 14.5 km south-west of Limbunya Stn H /S, large limestone hills with cliffs and karst formations in open woodland, small patches of vine thicket, spinifex, 17°18 ′ 20.6 ′′ S, 129°46 ′ 38.6 ′′ E (coll. T. Parkin, M. Braby, 24.vii.2010; NT-15 /10) ( AM C.475770).

Paratypes: Same data as for holotype, ten dry, nine wet ( AM C.470460); 14.2 km south-west of Limbunya Stn H /S, large limestone hills with cliffs and karst one wet ( AM C.462758); 27 km south-west of Limbunya Station, limestone outcrop with small vine thicket patches, in talus; 17°28 ′ 27.0 ′′ S, 129°53 ′ 14.0 ′′ E (coll. T. Parkin, 23.vii.2010), one wet ( AM C.475767) .

Etymology: In reference to the shell colour pattern, derived from ‘unus’ (Latin = one) and ‘striatus’ (Latin = striped), adjective of feminine gender.

Description: Shell ( Figs 4G , 6G , 26 ). Large, moderately elevated, thin; micropustulations absent. Shell background colour brown horn fading to whitish towards shell base, with one faint to very conspicuous brown-reddish spiral band on whorl periphery; maculations absent.

Genitalia ( Fig. 27 ). Epiphallus half of penis. Vas deferens entering penial sheath from halfway up. Penis eight times longer than wide, not coiled inside sheath, with inner wall supporting one posterior large longitudinal pilaster and several short basal pilasters, arising from different point of wall and often reaching genital pore. Vagina slightly shorter than penis and slightly longer than free oviduct, bursa copulatrix with long, rounded well-differentiated end.

formations in open woodland, small patches of vine thicket, spinifex, in talus, 17°18 ′ 27.3 ′′ S, 129°46 ′ 51.5 ′′ E (coll. V. Kessner, M. Braby, T. Parkin, 24.vii.2010; NT-14 /10), four wet ( AM C.470459); 17.5 km southwest of Limbunya Station , upper Stirling Creek drainage system, low limestone hills in open woodland beside seasonal stream, small pockets of vine thicket, spinifex, in talus, free sealer. 17°21 ′ 46.0 ′′ S, 129°47 ′ 55.0 ′′ E (coll. V. Kessner, M. Braby, T. Parkin, 23.vii.2010; NT-8 /10), 20 dry, five wet ( AM C.469984), 20 dry ( AM C.469985); 26.6 km south-west of Limbunya Stn H /S, open limestone slopes, few shady bushes, in deep talus, 17°24 ′ 22.2 ′′ S, 129°44 ′ 03.9 ′′ E (coll. V. Kessner, M. Braby, T. Parkin, 24.vii.2010; NT-16 /10), 20 dry, two wet ( AM C.469983) .

Other material: AUSTRALIA, NT, VRD, limestone hill 9.5 km south-west of VRD Station H /S, 16°27 ′ 35 ′′ S, 130°56 ′ 56 ′′ E (coll. V. Kessner, 15.vii.2008), four dry ,

Remarks: Widest umbilicus of genus together with E. montejinni . Shell colour pattern very similar to E. calciphila , E. floraevallis , E. gregoriana , E. limbunya , and E. rivifontis . Penis length relative to width (pl/pw) larger than the average, epiphallus length relative to penis (el/pl) half average. Penial inner wall sculpture very similar to E. brabyi , to be distinguished by posterior longitudinal pilaster being continuous and smaller number of anterior folds. Vagina length relative to penis (vl/pl) and vagina length relative to free oviduct (vl/ol) larger than average.

Figures

Figure 4. Photographs of living specimens of Exiligada species (courtesy Vince Kessner, Adelaide River). A, E. negriensis Iredale, 1939. B, E. pallida sp. nov. C, E. nodulicaudata sp. nov. D, E. punctata sp. nov. E, E. qualis Iredale, 1939. F, E. monochroma sp. nov. G, E. unistriata sp. nov. H, E. floraevallis sp. nov. I, E. rivifontis sp. nov.

Figure 6. Shells of Exiligada species. A, E. montejinni sp. nov. (paratype AM C.469982). B, E. nodulicauda sp. nov. (paratype WAM S49160). C, E. pallida sp. nov. (paratype WAM S49215). D, E. punctata sp. nov. (paratype WAM S49221). E, E. qualis Iredale, 1939 (holotype AM C.64866). F, E. rivifontis sp. nov. (WAM S49225). G, E. unistriata sp. nov. (paratype AM C.470460). Scale bar = 2 mm. Note that foot produces from some shells.

Figure 26. SEM micrographs of shell of E. unistriata sp. nov. (paratype AM C.469983). A, Apical view showing protoconch and first whorl. B, Close-up from above of sculpture across entire shell. C, Microsculpture on teleoconch whorl. Scale bars: A-B = 1 mm, C = 0.5 mm.

Figure 27. Penial anatomy of E. unistriata sp. nov. (holotype AM C.475770). Scale bar = 5 mm.