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An Illustrated Guide to the Land Snails of Sri Lankan Natural Forest and Cultivated Habitats
Abstract
A popular colour guide.
... Land snails play an important role in terrestrial communities, exhibiting substantial variations in shape, size and colour among species (Panha and Burch 2005;Raheem and Naggs 2006;Ramakrishna et al. 2010;Raheem et al. 2014). Among diverse land snails, micro-land snails are miniscule in size and occur in high abundances in certain habitats (Panha and Burch 2005). ...
... The habitats exploited by small land snails include detritus laden soil, as well as stems, bark, leaves and canopy of trees. The wide range of resources used by small land snails in these habitats allows classifying and characterizing them as herbivorous, detritivorous and predatory species (Raut and Ghose 1984a;Raheem and Naggs 2006;Sarma et al. 2007;Sen et al. 2012;Nandy et al. 2019). In many instances, small land snails cause the destruction of economically important crops and vegetables, and are therefore considered as pests (Raut and Ghose 1984a;Das et al. 1989;Barker 2002;Wilson 2007;Avhad et al. 2013). ...
... In many instances, small land snails cause the destruction of economically important crops and vegetables, and are therefore considered as pests (Raut and Ghose 1984a;Das et al. 1989;Barker 2002;Wilson 2007;Avhad et al. 2013). On a worldwide scale, studies on biology, ecology and diversity of small land snails highlight their ecological roles and the ecosystem services they provide (Barker 2001(Barker , 2002Raheem and Naggs 2006;Ramakrishna et al. 2010;Raheem et al. 2014;Budha et al. 2015). ...
The spatial distribution and morphological features of the land snail Succinea baconi (Pfeiffer, 1854) (Gastropoda: Succineidae) from India were evaluated. The survey performed in gardens and bushes in Coochbehar, West Bengal, India, has made it possible to assess the abundance of the snail S. baconi on the randomly selected lemon plants (n = 18). Logistic regressions were employed to judge differences in vertical distribution, resource association and size class variation in the snails under study. Variation in shell morphology was assessed by performing the regression analysis of the sampled shells of live snails (n = 258) and vacant shells of the deceased individuals (n = 100). An overall significant difference (p < 0.05) in the vertical distribution of snails in lemon plants was observed. As to their association with resources available, snails were found to be more abundant in detritus than on living parts of the plants. The performed logistic regression revealed that the relative abundance of different S. baconi size classes was significantly different (p < 0.001). Significant correlations (p < 0.001) were found among different body size variables, with the shell length (x)-body weight (y) relationship being: y = 0.232x 2.524 (for live snails) and the shell length (x)-shell weight (y) relationship being: y = 0.358x 2.537 (for shells of dead snails). Various parameters of the snail shell shape could be represented through regression equations. Although reproduction and growth strategies of snails need to be explored further, the presented observations improve our understanding of the ecology of S. baconi, which may prove useful for future conservation efforts.
... roseolabiata and A. superbus 'var. grevillei), and Acavus phoenix, consisting of two subspecies: Acavus phoenix phoenix and Acavus phoenix castaneus (Hausdorf and Perera 2000;Raheem and Naggs 2006). ...
... Though we do not have proper chronology from Nilgala, located in the proximity of Rajagala, the Sarasins also reported Cyclophorus (Litostylus) ceylanicus, Paludomus neritodes, and P. (Tanalia) loricata, with the first two in high abundance. Cyclophorus, like Acavus, prefers lowland rainforest conditions and is reported only in habitations in the southwest lowland wet zone of the island (Raheem and Naggs 2006;Raheem et al. 2008;. These malacofaunal pieces of evidence show significant humid phases in the SATZ occurred during the Terminal Pleistocene to early Holocene, in several events. ...
This study presents a discovery of Acavus haemastoma, wet-humid favouring arboreal land snails from Semi-Arid coastal lagoon habitat during the late Holocene period in Southern Sri Lanka, occurring around the mid-4th millennium BP. These findings challenge established notions regarding palaeoecological conditions within the Semi-Arid and Transitional Zones (SATZ), prompting a re-evaluation of prevailing archaeological assumptions. We propose that the presence of Acavus sp. in the SATZ is primarily attributed to their natural behaviours rather than anthropogenic influences. In conjunction with an examination of early archaeological literature, we explore the implications of humid phases within the SATZ, aligning these phases with Acavus snails’ distribution patterns and climatic fluctuations and proposing the value of land snails in
Sri Lanka as a potential proxy for small scale micro-climatic conditions.
... Genus Eutomopeas Pilsbry, 1946 32 Eutomopeas layardi (Benson, 1863) Spiraxis layardi Benson, 1863a: 90;Pfeiffer, 1868Pfeiffer, [in 1847Pfeiffer, -1877Hanley and Theobald, 1873: 34, Pl. 79, Figs, 2, 3 Stenogyra layardi (Benson); Nevill, 1878: 174 Opeas Pilsbry, 1906pl. 16, figs 82, 83;Gude, 1914a: 360 Opeas (Tomopeas) layardi (Benson); Pilsbry, 1906: 123 Opeas (Eutomopeas) layardi (Benson); Pilsbry, 1946a: 105 Lamellaxis (Eutomopeas) layardi (Benson); Zilch, 1959: 349 Eutomopeas layardi (Benson); Schileyko, 1999;Naggs et al., 2002;Raheem et al., 2006a Allopeas ? layardi (Benson); Naggs and Raheem, 2000: Fig. 117 Type material UMZC I.103270, Fig. 55 Remarks The number of specimens collected by Frederick Layard was not noted in the original description, but the type series was collected from several different localities and specimens with the polished epidermis were said to be very scarce. ...
... Pilsbry treated Eutomopeas as a subgenus of Opeas whereas Zilch (1959: 349) listed it as a subgenus of Lamellaxis. Eutomopeas has since been elevated to generic rank (Schileyko, 1999: 533;Naggs et al., 2003, Raheem et al., 2006a. Schileyko (1999) placed Eutomopeas in his Rishetiinae, together with Tortaxis and Bacillum Theobald, 1870, but in the molecular tree of Fontanilla et al. (2017), Eutomopeas falls within a clade that includes Allopeas and Prosopeas and these form a sister group to Leptinaria H. Beck, 1837. ...
... Laevicaulis altae Ferussae, 1821 is an exotic land slug found in home gardens and cultivations in the lowland wet zone and in the wetter parts of intermediate zone (Raheem & Naggs, 2006;Priyadarshana, 1998). This species prefers shady damp places, often seen around wells and ponds, on slippery stones and under damp dead leaves (Priyadarshana, 1998). ...
... The previous literature also explains the vigilant behaviour of the Red -wattled Lapwing (Ali & Ripley, 1978;Henry, 1998). L. altae and other exotic snails and slugs are pests for native biodiversity, which is a serious and growing problem in Sri Lanka (Naggs & Raheem, 2002;Raheem & Naggs, 2006). If the Red -wattled Lapwing is a common predator of the L. altae, it will be helped to control the spreading of this introduced slug. ...
Red–Wattled Lapwing is a common resident bird distributed throughout Sri Lanka. Laevicaulis altae is an exotic land slug found in home gardens and cultivations in the lowland wet zone and intermediate zone. L. altae and other exotic snails and slugs are pests, which is a serious and growing problem in Sri Lanka. This observation describes the behaviour of Red–Wattled Lapwing feeding on the exotic land slug at the premises of the Open University of Sri Lanka, Colombo.
... Several exotic invertebrates recorded from Sri Lanka are restricted to agricultural habitats, and function as pest species. Several species of European garden slugs (Deroceras retuculatum, D. leave, D. karuanae) have recently invaded the agricultural habitats in the central highlands above 1000 m elevations (Naggs, 2002;Mordan et al., 2003;Raheem and Naggs, 2006;Kumuburegama and Ranawana, 2007). The Potato cyst nematode (Globodera rostochiensis), originated in South American countries, was detected in Sri Lanka in the latter part of 1980's when it became a serious pest in the Nuwara Eliya district in the central province (Ekanayake, 1999). ...
... The role of some IAS in Sri Lanka as pests of agricultural crops in Sri Lanka has also been documented. The European garden slugs (Deroceras spp.) are pests of agricultural/horticultural crops, especially in the highland areas (Raheem and Naggs, 2006;Mordan et al., 2003). Deroceras reticulatum is a serious pest of many vegetables, especially of leaf crops such as cabbage and lettuce and the seedlings of root crops such as carrot. ...
... It is arguable that the natural forests support large number of endemic and non-endemic native mollusks fauna than by the nonforested areas (Naggs and Raheem, 2000). Also, according to Ranawana (2005), Raheem and Naggs (2006) it has been found that home gardens that are in close proximity to natural forests support greater number of endemic and non-endemic native land snails. ...
Terrestrial snails and slugs (Class Gastropoda) are a diverse group of mollusks found in diverse habitats. Some of the terrestrial snails and slugs are serious pests of agriculture and horticulture in many countries of the world. Often these pests are exotic, invasive species introduced through trade and commerce. They spread rapidly causing severe damage to crops resulting in heavy economic losses. These pest species also have the potential to displace native snails and slugs in these altered environments as well as invade natural habitats.
Sri Lanka is home to 253 species of terrestrial gastropods out of which 81% are endemic to the country. An island wide survey conducted from 1999 to 2002 also highlighted the presence of 18 species of exotic snails and slugs in the country. Most of these exotic species were identified as pests of agricultural crops in Nuwara Eliya, Badulla, Matale and Kandy districts. Since this survey, no studies on pest gastropods have been carried out in the country. Hence, a study was carried out in Kandy and Nuwara Eliya districts in approximately 149,734 m2 of agricultural land from January to October 2017 to determine the current status of these gastropods in these areas. The distribution and density of pest gastropods were assessed in relation to three environmental variables: elevation, temperature and relative humidity using a canonical correspondence analysis (CCA).
During the study, a total of 14 terrestrial gastropods were identified of which 8 gastropod species were recognized as pests of agriculture crops. They were Laevicaulis altae, Mariaella dussumieri, Deroceras reticulatum, Milax gagates, Lissachatina fulica, Bradybaena similaris, Allopeas gracile and Subulina octona. Among these, Lissachatina fulica is also listed as an Invasive Alien Species (IAS) in Sri Lanka. In addition to these pest species, four endemic species, namely, Cryptozona chenui, Euplecta emilina, E. hyphasma and Satiella sp. Two non-endemic species, C. bistrialis and Eurychlamys vilipensa were also observed associated with agricultural fields. However, even though some of these species were highly dense there were no direct observations of these species causing damage to crop plants. The study indicated that the number of pest gastropod species occurrences in agricultural lands has increased during the past fifteen years. Some species have increased their distribution range. The elevation was the most significant factor in determining the gastropod species variation in different sites.
The damages due to pest gastropods were prominent in cash crops and irrespective of the crop type the seedling or nursery stage was the most preferred and hence most vulnerable. Farmers
used physical methods such as manual removal of snails and chemical methods such as application of Metaldehyde, common salt, quick lime and urea. Yet due mainly to the ineffective usage of these chemical, it has failed in controlling pest gastropods effectively. Thus, regular monitoring and effective control measures are necessary to minimize the adverse effects of these pest gastropods.
... While all the identified pest gastropods species are non-native to Sri Lanka, the country itself boasts a rich diversity of terrestrial gastropods, with over 80% of the recorded 253 species being endemic (Raheem et al. 2006). Many of the Sri Lankan gastropods require forests and most of the native gastropod species are found concentrated in either lowland or submontane/montane rainforests, especially in the wet zone of the country (Raheem et al. 2008;Ranawana 2016). ...
Background: The available information on terrestrial pest gastropods and their impact on the environment worldwide is scarce and outdated. The present study aimed to address this gap by conducting the first comprehensive survey of pest gastropods in the Nuwara Eliya District, an important vegetable growing area in the highlands of Sri Lanka. Eighty agricultural lands were surveyed over two years by establishing ten 1 m2 sampling plots per crop type in each agricultural land. Geo-coordinates, air temperature, elevation, relative humidity, daily rainfall, soil pH, species richness and abundance were recorded for rainy and non-rainy periods. The relationship between species composition and environmental variables was analyzed using multi-regression models and distribution maps.
Results: Out of the 14 species recorded in agricultural lands, nine were identified as exotic pest species. Species abundance (t = 4.69, p < 0.05) and diversity was higher in the rainy period and the dominant species during this period were Bradybaena similaris (t = 2.69, p < 0.05) and Deroceras reticulatum (t = 2. 46, p < 0.05). Eggs and estivating adults were found in soil and under decaying organic matter during the non-rainy period. The exotic species showed broader preferences for the measured environmental factors and showed a wider range in distribution compared to the native species. Variation in pest gastropod composition was significantly accounted for by elevation, relative humidity, soil pH and daily rainfall. Additionally, the species richness and abundance varied across locations due to the combined effects of elevation, crop type and stage, and field type.
Conclusions: The study emphasizes the importance of understanding the biology and ecology of gastropod pests to develop effective management strategies. By considering the influence of environmental factors and implementing appropriate soil management techniques, such as targeting specific habitats and crop stages, it is possible to mitigate pest populations and minimize their impact on agricultural lands. Overall, this research contributes valuable insights into the dynamics and interactions of terrestrial gastropods in agricultural ecosystems, supporting sustainable pest management practices.
... Hanley did not believe in geographical distribution and soon removed it [locality data]." Nonetheless, students of the Indian molluscan fauna have to use the Conchologia Indica, because it has many new species of land snails from two biodiversity hotspots -the Western Ghats (the mountainous region of southwestern India) and Sri Lanka (Naggs & Raheem, 2000;Raheem & Naggs, 2006;Raheem et al., 2009). ...
The malacological works of Sylvanus Hanley (and his relative Charles Thorpe) are discussed and their dates in some cases clarified. The taxa that first appear in these works are listed, their type specimens noted when known, and the current status of the available taxa discussed. Of the 375 species-group names that first appear in these works, 367 are available, and 8 are nomina nuda. Of the 367 available species-group taxa, approximately 219 are now considered valid. Ap-proximately 60% of the available species are represented by type material, mainly in the Natural History Museum in London and in the Leeds City Museum in Leeds, U.K. Hanley also described several genus-group and family-group names, some of which are still considered valid.
This study investigates pre-colonial and colonial-era pearl fisheries in Sri Lanka using archaeological data from the Gulf of Mannar (GoM). Following surface surveys, test pits were excavated in three pearl oyster middens and one coastal settlement. The archaeomalacological study of the molluscan remains from the middens confirms that the pearl oyster (Pinctada fucata) was the predominant species exploited, providing a clear picture of the pearl oyster bank ecosystems used at the industrial level. Morphometric analysis of the pearl oysters allows for an assessment of exploitation pressure. Ceramic and radiocarbon analyses date the high impact of the pearl industry from the tenth to the nineteenth centuries. The study of by-catch fauna provides insight into pearl bank ecosystems over time. These archaeological findings highlight the impact of industrial extractions on a single species.
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