Gastrocopta larapinta (Tate, 1896)

Whisson, Corey S. & Koehler, Frank, 2013, Gastrocopta (Mollusca, Gastropoda, Pupillidae) in the Pilbara region of Western Australia, ZooKeys 261, pp. 15-39 : 22-25

2. Gastrocopta larapinta (Tate, 1896) Fig. 2 C–E

Pupa larapinta Tate 1896: 205-206, pl. 19, figs 19 a–b.

Gastrocopta larapinta Pilsbry 1917 [in 1916-1918]: 168-171, pl. 30, figs 5 –7,9– 11; Solem 1989; 490-491, figs 54-55; 1991: 249; Pokryszko 1996: 1109-1110, figs 19, 22.

Australbinula larapinta Iredale 1937a: 302; 1937b: 10.

Type locality.

Central Australia.

Material studied.

Western Australia: Cane River: 22.0298°S, 115.4296°E (WAM S42993). Central Pilbara: 22.3855°S, 117.4667°E (WAM S58492, WAM S65790); 22.3200°S, 117.6194°E (WAM S65778); 22.2675°S, 117.7197°E (WAM S65780); 22.1350°S, 117.4728°E (WAM S58493); 21.0216°S, 117.0560°E (WAM S65817); 20.7506°S, 117.0096°E (WAM S65797). Christmas Creek: 22.4061°S, 119.7376°E (WAM S65612); 22.3985°S, 119.7930°E (WAM S65604). Cloud Break area: 22.3210°S, 119.4442°E (WAM S34453, WAM S80956); 22.2688°S, 119.3147°E (WAM S61128); 22.3652°S, 119.3409°E (WAM S65150); 22.3985°S, 119.4748°E (WAM S65156); 22.3949°S, 119.5019°E (WAM 65161); 22.3527°S, 119.4189°E (WAM S65135). Collier Rocks: 20.4071°S, 116.8514°E (VK 30297). Cy Creek: 22.8183°S, 114.0609°E (WAM S34381). Du Boulay Creek: 21.1833°S, 116.1833°E (WAM S34569). Fortescue Marsh area: 22.2930°S, 119.0606°E (WAM S61996-7); 22.4646°S, 119.7726°E (WAM S64651, WAM S64654); 22.4430°S, 119.7785°E (WAM S64649); 22.4252°S, 119.7235°E (WAM S64635); 22.3125°S, 119.2348°E (WAM S64634, WAM S64637); 22.2875°S, 119.1701°E (WAM S64650); 22.2822°S, 119.1276°E (WAM S42923, WAM S64644, WAM S64652, WAM S64694). Hope Downs: 23.1030°S, 119.5821°E (WAM S59298); 23.0919°S, 119.1875°E (WAM S59550). Jimblebar: 23.3693°S, 120.1958°E (WAM S41346). Kalgan Pool area: 23.1877°S, 119.6965°E (WAM S58005); 23.1874°S, 119.6957°E (WAM S80939). Koodaideri Corridor West (90.4km NW of Tom Price): 21.8833°S, 117.7000°E (WAM S83434). Marillana Station: 22.6260°S, 119.2834°E (WAM S34638); 22.5840°S, 119.3114°E (WAM S34632, WAM S34472); 22.5739°S, 119.2562°E (WAM S34474); 22.5666°S, 119.2327°E (WAM S34637); 22.5663°S, 119.2308°E (WAM S34633); 22.6013°S, 119.2913°E (WAM S80924); 22.5625°S, 119.2311°E (WAM S80908); 22.1269°S, 119.2123°E (WAM S80911); 22.4080°S, 119.0067°E (WAM S80914); 22.4285°S, 119.2043°E (WAM S8143940); 22.3476°S, 119.1518°E (WAM S81433); 22.4295°S, 119.1923°E (WAM S81446). Millstream National Park: 21.2000°S, 117.2667°E (WAM S60343); 21.6000°S, 117.1000°E (WAM S 61044); 21.5833°S, 117.1000°E (WAM S 61048); 21.5833°S, 117.0833°E (WAM S60944-5); 21.5833°S, 117.0667°E (WAM S 60947); 21.4255°S, 117.0535°E (WAM S81213); 21.2039°S, 117.0440°E (WAM S81267). ca. 30km NNE of Newman: 23.1164°S, 119.8865°E (WAM S64469). ca. 65km NW of Newman: 22.9169°S, 119.2128°E (WAM S80937). ca. 108118km N of Newman: 22.3132°S, 119.8599°E (WAM S65534, WAM S65673); 22.3134°S, 119.7886°E (WAM S65646); 22.2972°S, 119.8633°E (WAM S65530, WAM S65682); 22.2954°S, 119.8109°E (WAM S65652). North Star Mine: 21.2284°S, 119.0386°E (WAM S65720); 21.2104°S, 118.8769°E (WAM S65723). Phil’s Creek: 22.7412°S, 119.1959°E (WAM S59388, WAM S80934); 22.7320°S, 119.1836°E (WAM S59374). ca. 100km S of Port Hedland: 20.6066°S, 119.5016°E (WAM S80942). ca. 200km SSE of Port Hedland: 22.1554°S, 119.0216°E (WAM S83486). Robe River area: 21.8063°S, 116.0774°E (WAM S42832). 6km SW of Redmont Airport: 22.0195°S, 118.9816°E (WAM S83423). NNE of Rocklea Homestead: 22.7882°S, 117.4974°E (WAM S80977). Roy Hill Station: 22.4898°S, 119.8951°E (WAM S34703); 22.4547°S, 119.8709°E (WAM S42924, WAM S60428-9, WAM S65389); 22.4943°S, 119.9217°E (WAM S60359, WAM S60368, WAM S60373, WAM S60378); 22.5383°S, 119.9424°E (WAM S42831, WAM S42833, WAM S60232, WAM S60857, WAM S60861); 22.4793°S, 119.9420°E (WAM S42925, WAM S60363, WAM S60426, WAM S60853, WAM S60860); 22.6394°S, 119.9642°E (WAM S60398); 22.5769°S, 119.9952°E (WAM S603667, WAM S608545, WAM S60859); 22.5771°S, 120.0247°E (WAM S60422); 22.7058°S, 119.7082°E (WAM S60392); 22.6430°S, 119.9599°E (WAM S60396); 22.6076°S, 119.9826°E (WAM S60388); 22.6593°S, 119.9198°E (WAM S60397); 22.6642°S, 119.9458°E (WAM S61066, WAM S61069); 22.6431°S, 119.9642°E (WAM S61075, WAM S61077); 22.6225°S, 119.9634°E (WAM S610723); 22.5050°S, 119.9143°E (WAM S64455). Running Waters (east of Nullagine): 21.6819°S, 121.1254°E (WAM S58039, WAM S58050); 21.6806°S, 121.1261°E (WAM S58032). 15km W of Shaw River Airport: 21.6123°S, 119.2642°E (WAM S83412). Wonmunna: 23.1220°S, 119.0611°E (WAM S81087, WAM S81182); 23.1356°S, 119.0463°E (WAM S81107, WAM S81125, WAM S81164); 23.1216°S, 119.0498°E (WAM S81096); 23.1201°S, 119.0484°E (WAM S65993, WAM S80904). ca. 18-23km SE of Wodgina Mine: 21.2273°S, 118.8336°E (WAM S646089); 21.2871°S, 118.8671°E (WAM S64604, WAM S64616). ca. 20km NNE of Wodgina Mine: 21.0260°S, 118.7024°E (WAM S64610). Yule River area: 21.6961°S, 118.8604°E (WAM S83372).

Distribution.

This species has previously been recorded fromcentral Australia (southern part of Northern Territory) with fewer records in north-western Queensland (Gregory River Basin); eastern coast of Queensland and a single record from the Oscar Ranges, in the southern Kimberley region of Western Australia ( Pokryszko 1996). In addition, it is now recorded from throughout most of the Pilbara region, but is surprisingly absent from near coastal areas and islands (Figure 4).

Comparative morphology.

The shells of typical Gastrocopta larapinta specimens are distinguished from most other Gastrocopta species in the Pilbara by (1) their large size (2) usually the presence of three solid palatal teeth (the interpalatal tooth varying from a tiny callus to large tooth) (3) a short, solid parietoangular tooth that is usually deflected or curved moderately toward the columellar wall so that its anterior end is somewhat vertical in the apertural view (4) a long angular tooth that is generally fused (or connected via a translucent callus) to the parietoangular tooth, occasionally separate (particularly those that lack or have a small interpalatal tooth) (5) smaller, more rounded columellar tooth that curves or angles abruptly toward the columellar wall (6) usually the presence of an infraparietal tooth or basal tooth (or both).

Typical Gastrocopta larapinta shells with a small interpalatal tooth (or very occasionally no interpalatal tooth) appear considerably more variable in apertural barrier structure (particularly in high calcareous soils), making their separation from the cylindrical and elongate-ovate forms of Gastrocopta mussoni difficult. As such the following separation is tentative. Gastrocopta larapinta shells are typically (1) slightly to moderately larger (obese) (2) have a slightly smaller, more rounded columellar tooth (3) usually a much shorter parietoangular tooth that is positioned lower in apertural view (4) generally possesses an infraparietal tooth (5) often a slightly lower, less convergent upper palatal tooth (6) usually a less sigmoid lower palatal tooth.

Remarks.

The separation of Gastrocopta larapinta (small or no interpalatal tooth) with the cylindrical and elongate-ovate forms of Gastrocopta mussoni has proved extremely difficult and a more detailed molecular study is required to resolve this issue. Pokryszko (1996) separated these Gastrocopta larapinta specimens from cylindrical Gastrocopta mussoni based on shell size (smaller) and columellar tooth angle (less acute). However, from the small genetic data available and from examination of many shells, Gastrocopta larapinta shells were slightly, to moderately more obese.

Some of those near west coast specimens (Cy Creek) included as cylindrical Gastrocopta mussoni contained mixed lots of Gastrocopta larapinta and Gastrocopta mussoni . Interestingly, Poykryszko had identified a few of these larger Cy Creek specimens as Gastrocopta larapinta , but included those records as Gastrocopta mussoni in her publication. Pokryszko (1996) also noted in a large lot of Gastrocopta mussoni from central Australia (FMNH 201570) that some of the ovate Gastrocopta mussoni were quite large (many having an interpalatal tooth) but we consider most of those to be Gastrocopta larapinta with a small or no interpalatal tooth (see Gastrocopta mussoni section).

It is possible Pokryszko (1996) was alluding to a slender form of Gastrocopta larapinta when separating cylindrical Gastrocopta mussoni and Gastrocopta larapinta (no interpalatal tooth) but this does not reflect accurately in her identifications. During this study specimens from Kalgan Pool (WAM S58005) were unexpectedly grouped within the Gastrocopta larapinta clade. These specimens, although slightly more slender, have proven difficult to separate from cylindrical Gastrocopta mussoni specimens identified by Pokryszko (1996) as they (1) have a high, long, lamellate parietoangular tooth (2) have a separated angular tooth (3) have a slightly rounded to angled columellar tooth and (4) lack an infraparietal tooth. They may prove to be a subspecies of Gastrocopta larapinta and in this sense, Pokryszkos’ ( 1996) separation of cylindrical Gastrocopta mussoni and Gastrocopta larapinta (no interpalatal tooth) was correct.

As there is doubt surrounding the distinguishing morphological characters of cylindrical Gastrocopta mussoni and Gastrocopta larapinta shells with a small or no interpalatal tooth, the above separation is tentative and a more detailed genetic investigation is required.