Neripteron violaceum ( Gmelin, 1791 )

Mustapha, Nurshahida, Baharuddin, Nursalwa, Tan, Siong Kiat & Marshall, David J., 2021, The neritid snails of Brunei Darussalam: their geographical, ecological and conservation significance, Ecologica Montenegrina 42, pp. 45-61 : 52-53

Neripteron violaceum ( Gmelin, 1791)

Figs. 3E–F and 4I

Nerita violacea Gmelin, 1791: 3686 .

Neritina violacea – Tan & Clements, 2008: 490, figs. 3-33, 3-34.

Neripteron (Dostia) violaceum – Eichhorst, 2016a: 392, pl. 102.

Material. UBDM.7.00100. Sample was collected from SK.

Abundance. Abundant.

Habitat. Associated with brackish water. On muddy surfaces, rocks and mangroves in brackish water environments.

Local distribution. SK, SD and SBu.

Ecology and conservation. Widely distributed in the Sungai Brunei estuarine system. At some rocky localities, it is fairly abundant and closely cohabits with Nerip. cornucopia . Neripteron violaceum is exposed to highly acidic environmental condition and faces shell dissolution ( Proum et al. 2018). Of low conservation importance.

Taxonomy. Descriptions in the literature often confuse the sister species, Nerip. violaceum and Nerip. cornucopia . This partly stems from the variable shell colours in either ( Tudu et al. 2017). They can readily be differentiated as follows (see Figs. 4I–J ). [1] in Nerip. cornucopia the shell lip is distinctly flared whereas in Nerip. violaceum the shell lip is not flared and; [2] in Nerip. cornucopia the apex (spire) is located midway between the parietal edge (lip) and the upper surface of the shell, but in Nerip. violaceum the apex meets the anterior parietal edge ( Fig. 4 ).

Biogeographical distribution. SB, PL, TH and SG. Generally distributed in Indo-West Pacific ( Eichhorst 2016a).

I J K L

Figure 3. Neritidae species found associated with upper estuarine and brackish water habitats in Brunei Darussalam, shown in apertural and abapertural view. A–B. Neritodryas dubia ( Gmelin, 1791) . C–D. * Vittina coromandeliana (G. B. Sowerby I, 1836) . E–F. Neripteron violaceum ( Gmelin, 1791) . G–H. * Neripteron cornucopia ( Benson, 1836) . I-J. * Neripteron spirale (Reeve, 1855) . K–L. Clithon oualaniense ( Lesson, 1831) . (*) indicates a new species record for Brunei Darussalam. Scale bar represents 3 mm.

Figures

Figure 4. Side view showing off spire plasticity amongst Nerita species found in Brunei Darussalam. A. Nerita albicilla Linnaeus, 1758. B. Nerita litterata Gmelin, 1791. C. Nerita insculpta Récluz, 1841. D. Nerita patula Récluz, 1841. E. Nerita chamaeleon Linnaeus, 1758. F. Nerita undata Linnaeus, 1758. G. Nerita balteata Reeve, 1855. H. Nerita planospira Anton, 1838. I. Neripteron violaceum (Gmelin, 1791). J. Neripteron cornucopia (Benson, 1836). K. Vittina coromandeliana (G. B. Sowerby I, 1836). L. Neritodryas dubia (Gmelin, 1791). M. Clithon oualaniense (Lesson, 1831). N. Neripteron spirale (Reeve, 1855). O. Nerita histrio Linnaeus, 1758. P. Nerita exuvia Linnaeus, 1758. Markings on I and J: the spire hangs further midway in N. cornucopia compared to N. violaceum. Scale bar on top represents 3 mm, unless stated otherwise.