Exiligada negriensis, IREDALE, 1939

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: 696-700

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http://doi.org/ 10.1111/j.1096-3642.2012.00863.x

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Exiligada negriensis



( FIGS 4A View Figure 4 , 5A View Figure 5 , 7A–C View Figure 7 , 8 View Figure 8 )

Exiligada negriensis Iredale, 1939: 69   , plate V, figure 4.

Exiligada negriensis   – Solem, 1984: 673–677, fig. 174 (a–c) (in part).

Material examined: AUSTRALIA, NT, VRD: holotype from 40 km north of Ord River Station , Negri outstation (coll. R. Helms, 1896), dry ( AM C.64865); ten paratypes (same data as for holotype) ( AM C.64916); 6 km south-west of Lissadell Station homestead (H/S), limestone outcrops with slabs on upper slopes, spinifex, patches of vine thicket, in talus, under boulders, 16°43 ′ 16 ′′ S, 128°31 ′ 23 ′′ E, (coll. V. Kessner, R. Hokkanen, 28.viii.2009; WA-57 /09) two wet ( WAM S49214 View Materials ) GoogleMaps   , 12 dry ( WAM S49145 View Materials )   ; 9.5 km south-east of Lissadell Station H/S, limestone ridge east of Ord River, dissected limestone area with small vine thicket patches on the slopes, exposed on the top, under talus, 16°43 ′ 07 ′′ S, 128°37 ′ 51 ′′ E (coll. V. Kessner, R. Hokkanen, 28.vii.2009; WA-58 /09), 18 dry ( WAM S49146 View Materials ) GoogleMaps   ; south-east of Lake Argyle , 15.5 km south-west of Behn River crossing, large limestone mass with karst formations, vine thicket patches, native grasses, under slabs, 16°37 ′ 20 ′′ S, 128°48 ′ 47 ′′ E (coll. V. Kessner, R. Hokkanen, 28.viii.2009; WA-59 / 09), 32 dry ( WAM S49147 View Materials ) GoogleMaps   ; 29.8 km north of Spring Creek Station H/S, East Kimberley limestone gully along a seasonal stream with vine thicket patches, under large slabs, 16°43 ′ 40 ′′ S, 128°52 ′ 25 ′′ E (coll. V. Kessner, R. Hokkanen, 28.viii.2009; WA-60 /09), 16 dry ( WAM S49148 View Materials ) GoogleMaps   ; 1 km south of Negri River junction, east bank of Ord River, narrow and open limestone ridge, very dry, dead in crevices, 17°04 ′ 38 ′′ S, 128°53 ′ 48 ′′ E (coll. V. Kessner, R. Hokkanen, 29.viii.2009; WA-65 /09), 13 dry ( WAM S49149 View Materials ) GoogleMaps   ; 30.4 km east-south-east of Spring Creek Station H/S, limestone gully along a stream, cliffs 8–10 m high, base of limestone cliffs along a seasonal stream, talus, spinifex and native grass, 17°02 ′ 04 ′′ S, 129°08 ′ 35 ′′ E (coll. V. Kessner, R. Hokkanen, 30.viii.2009; WA-67 / 09) one wet ( WAM S83171 View Materials ) GoogleMaps   , 130 dry, two wet ( WAM S49151 View Materials )   ; 39.6 km south-east of Spring Creek Station H/S, low limestone cliffs over sandstone base south of Stirling Creek, spinifex and native grass, in talus, 17°11 ′ 20 ′′ S, 129°10 ′ 35 ′′ E (coll. V. Kessner, R. Hokkanen, 30.viii.2009; WA-68 /09), 1 wet, 53 dry ( WAM S49152 View Materials ) GoogleMaps   ; low exposed limestone hills in Nelson Creek drainage, Limbunya Station, limestone layer over sedimentary rocks, spinifex, in rock piles, under spinifex, 17°18 ′ 23 ′′ S, 129°12 ′ 29 ′′ E (coll. V. Kessner, R. Hokkanen, 30.viii.2009; WA-69 /09), eight wet ( WAM S49216 View Materials ) GoogleMaps   , 29 dry ( WAM S49153 View Materials )   ; 30.2 km north-east of Kirkimbie Station (Stn) H/S, karst limestone formation in open woodland, spinifex, 17°29 ′ 23 ′′ S, 129°22 ′ 46 ′′ E (coll. V. Kessner, R. Hokkanen, 2.ix.2009; WA-82 /09) one wet ( WAM S83172 View Materials ) GoogleMaps   ; 21.6 km north of Kirkimbie Station H/S, narrow limestone ridge, steep open slopes, well-developed spinifex on upper slopes, in talus, under spinifex, 17°32 ′ 20 ′′ S, 129°16 ′ 03 ′′ E (coll. V. Kessner, R. Hokkanen, 2.ix.2009; WA-83 /09), six wet ( WAM S49218 View Materials ) GoogleMaps   , 20 dry ( WAM S49161 View Materials )   ; west of Duncan Highway ( Hwy ), Spring Creek Station, limestone area east of Mud Spring Creek, open limestone slopes, well-developed spinifex, dead under slabs, 16°41 ′ 20 ′′ S, 128°54 ′ 55 ′′ E (coll. V. Kessner, R. Hokkanen, 3.ix.2009; WA-85 /09), one dry ( WAM S49162 View Materials ) GoogleMaps   ; 5.4 km south-west of Lissadell Stn H/S, low limestone ridge, base of the cliffs, small pockets of vine thicket, under rocks in loose soil, 16°42 ′ 31 ′′ S, 128°30 ′ 58 ′′ E (coll. V. Kessner, K. Carnes 6.ix.2009; WA-97 /09), two dry ( WAM S49166 View Materials ) GoogleMaps   ; 6.7 km south-west of Lissadell Stn H/S, narrow limestone ridge, base of the cliffs, small pockets of vine thicket, spinifex, under rocks, 16°43 ′ 17 ′′ S, 128°30 ′ 46 ′′ E (coll. V. Kessner, K. Carnes, 6.ix.2009; WA-98 /09), two dry ( WAM S49219 View Materials ) GoogleMaps   , nine dry ( WAM S49163 View Materials )   ; 12 km south-west of Lissadell Stn H/S, low limestone exposed hill with karst limestone, few shady trees, spinifex and tussock grass, in talus, 16°46 ′ 16 ′′ S, 128°30 ′ 09 ′′ E (coll. V. Kessner, K. Carnes, 6.ix.2009; WA-99 /09), 16 dry ( WAM S49164 View Materials ) GoogleMaps   .

Description: Shell ( Figs 4A View Figure 4 , 5A View Figure 5 , 7A–C View Figure 7 ). Large, moderately elevated, moderately thick; micropustulations absent; background colour yellowish horn fading to whitish towards shell base, with several conspicuous to faint brown-reddish spiral bands, equally conspicuous on entire shell, often present on base, often interrupted radially; no maculations.

Genitalia ( Fig. 8 View Figure 8 ). Epiphallus as long as penis. Vas deferens entering penial sheath halfway up. Penis five times longer than wide, not coiled inside sheath, inner penial wall with weak, irregular longitudinal pilasters restricted to anterior half, posteriorly with thick, cone-shaped pad. Vagina half as long as penis, a third of length of free oviduct, bursa copulatrix with elongated, pointed well-differentiated end.

Remarks: The species is delimited here differently as compared to the latest revision of Solem (1984). Originally, amongst a single set of mostly eroded shells from the same locality, Iredale (1939: 69) recognized two Exiligada species   based on shell morphology and coloration: E. negriensis   , which he designated as the type species of the genus Exiligada   , and E. qualis   . The type locality as originally cited by Iredale (1939) (‘Negri Outstation’) could not be specified subsequently ( Solem, 1984). However, based on the information provided by Iredale [25 miles (= 40 km) north of Ord River Station, near Negri River], the type locality is herein restricted to an area close to the Negri River between the point where the Negri River flows into the Ord River in WA (17°04 ′ 11 ′′ S, and E. brabyi   both having shells with continuous spiral bands.

Exiligada negriensis   differs from Exiligada pallida   in absence of micropustulations on the shell. Its shell colour pattern is similar to that of four other Exiligada species   , which are distinguished by a lower number of spiral bands ( E. longicauda   ), by bands being more regularly interrupted ( E. nodulicauda   ), by lighter background ( E. pallida   ), and presence of maculations ( E. punctata   ). Its penis length relative to width (pl/pw) is smaller than average, almost as large as in E. pallida   ; epiphallus length relative to penis (el/pl) is average, as large as in E. pallida   . Inner penial wall sculpture is very similar to E. pallida   and E. punctata   , differing by wider posterior pad and shorter longitudinal pilasters of the penial wall never extending to posterior part of wall. Vagina length relative to penis and free oviduct (vl/pl, vl/ol) is the smallest amongst congeners.

128°53 ′ 10 ′′ E) and the Duncan Highway bridge over the Negri River near the WA / NT border (17°04 ′ 32 ′′ S, 129°00 ′ 10 ′′ E). Solem (1984: 672–673) considered the differences between the type series of E. negriensis   and E. qualis   as not significant and synonymized the two species names. Based on comparative study of additional material, we found that the area including the type locality is inhabited by three Exiligada species.   Differences between two of these species as delimited herein are consistent with the original delimitation of E. negriensis   and E. qualis   by Iredale (1939), refuting Solem’s (1984) proposal that both were identical (see also below under E. qualis   ). To complicate matters even further, Solem (1984: 676) used specimens from ‘Duncan Hwy, 37.2 km N of Nicholson River’ (about 60–70 km south of the type locality) to describe the genital anatomy of what he considered to be E. negriensis   . We studied material from sites much closer to the type locality and found that E. negriensis   differs from Solem’s (1984: 676, fig. 175) anatomical description. Based on shell colour patterns, we found that he used specimens from a different species, named herein Exiligada brabyi   further below, to illustrate the genital anatomy of E. negriensis   . Hence, Solem’s (1984) description of ‘ E. negriensis   ’ is based on mixed material from three species ( E. negriensis   , E. qualis   , E. brabyi   ). His description and figure of genital features is here attributed to E. brabyi   (see below). Exiligada negriensis   as restricted here is defined by the presence of dashed spiral bands on shells as opposed to E. qualis  


Australian Museum


Western Australian Museum














Exiligada negriensis

Criscione, Francesco, Law, Margot Louisa & Köhler, Frank 2012

Exiligada negriensis

Solem A 1984: 673

Exiligada negriensis

Iredale T 1939: 69