The species was described by Fritz et al. (2005) as a full species in the Emys orbicularis complex, based on molecular distinction; the species is also morphologically distinct.

Spinks and Shaffer (2009) found E. trinacris to nest within E. orbicularis when using nuclear DNA, however, when mtDNA was used, it appeared to be in a separate clade.

The Taxonomic Committee of the Societas Europaea Herpetologica (Speybroeck et al. 2020) suggested taking a conservative stance and treated E. trinacris as a subspecies of E. orbicularis, pending further studies to resolve the complicated relationships of the Emys complex.

This assessment follows TTWG et al. (2021) in placing E. trinacris and E. orbicularis as separate species. In addition, Vamberger et al. (2015) found close agreement between taxonomic (following Fritz et al. 2005) and genetic differentiation, both with respect to mitochondrial and nuclear markers. The Sicilian haplotype has been found in southern mainland Italy (Calabria) only once in one individual (Lenk et al. 1999, Vamberger et al. 2015), but this requires further study and may reflect the introduction of Sicilian animals to southern mainland Italy (i.e., genetic pollution), rather than being of taxonomic significance.

This species is native-endemic to Sicily (Italy) in Europe, where the species is widespread across much of the island and can be abundant at some sites. However, there has been extensive loss of wetlands over the past 100 years (the three-generation length period for this species is 42-48 years) but it is unknown if the population of this species has been affected, and if so, to what extent, noting that the species is able to utilise a range of habitats, including anthropogenic wetlands. However, it is likely that the ongoing habitat loss may have consequently caused a decreasing population size of turtles because the artificial wetlands cannot compensate in terms of the quality the natural habitat conditions for this species. The area of occupancy (AOO) is considered to be ca.5,000 km² and the extent of occurrence (EOO) is a maximum of 26,114 km², both exceeding the threshold for a threatened Category. The number of threat-defined locations has not been estimated, but the number of locations is likely to significantly exceed ten given the localised nature of the known threats.

Therefore, the species is considered Data Deficient at present, and research into population size and trend, distribution, and threats to the Sicilian Pond Turtle is required in order to determine the conservation status of the species. It would be important to undertake niche modelling studies to determine the extent of potential habitat distribution. The data and information currently available make the potential assessment ranging from LC (widespread, able to utilise a wide range of natural and anthropogenic habitats) to EN or perhaps CR (depending on the scale of any population decline over the past three generation length period), so DD is considered appropriate.

This species is endemic to the island of Sicily (Italy), where it is widespread across a large part of the main island. The species seems to have a localised occurrence within suitable habitat (Ottonello et al. 2021a), although it is quite possible that it has gone undetected at additional sites because of suboptimal field research and/or elusive habits, and it is not considered to be severely fragmented. The species is not found on the surrounding minor islands (Ottonello et al. 2021a).

The Sicilian Pond Turtle is generally more common in northern central-western parts of the island, with the exclusion of Monti Peloritani, most of the Madonie area, and Monti di Termini Imerese. It appears to be rarer in southeastern coastal areas, except for some coastal wetlands (Ottonello et al. 2021a). It occurs from sea level up to ca. 1,250 m asl (Marrone et al. 2016, Vecchioni et al. 2017, 2020a), with anecdotal records to higher elevations (Ottonello et al. 2021a); Andreone et al. (2013) give 1,400 m as the upper elevation range.

The area of occupancy (AOO) ranges from 340 km² (based on available point data records; considered a significant under-estimate) to 6,000 km² (an estimate derived from the presumed historical indigenous range of 11,954 km² (TTWG 2021) less habitat loss); the current AOO value is considered to be ca. 5,000 km²). The species estivates in hot summers, making surveys more difficult in some areas, and estimates of AOO based on locality records are considered to be under-estimates. The extent of occurrence (EOO) ranges from 23,686 km² (based on available point data) to 29,326 km² (measured as convex polygon from the current distribution map; TTWG in press).

Introduced E. trinacris individuals (not mapped) have been reported from mainland Italy (Lenk et al. 1999, Vamberger et al. 2015) and in Germany (a few individuals, no reproducing subpopulations in either case; D. Ottonello pers. comm. January 2023), with a hybridised subpopulation (with E. o. hellenica) in northeastern Italy (Ottonello et al. 2021a).

There are few studies of population size and trend, and no overall estimate of population size. In particular, there are no studies of its long-term population dynamics, and thus knowledge of the population characteristics of this species is scarce. Ottonello et al. (2017), based on surveys of the subpopulation inhabiting the Gorgo Basso in the Lago Preola and Gorghi Tondi Nature Reserve recorded 719±47 turtles at this one site. Based on the above-mentioned short-term study, the annual survival rate was 80% in females and 76% in males, which is lower than that of the closely related European Pond Turtle Emys orbicularis. This annual survival rate is so low in fact that a PVA would show a rather steep decline in the population as a long-lived species cannot obviously afford 20+% annual attrition of adults (and even higher mortality rates of juveniles, which is a feature of all turtles). However, these data are too preliminary and considered unrepresentative of the overall population (D. Ottonello pers. comm. January 2023) and further studies are needed before arriving at a firm conclusion. Further, Ottonello et al. (2021a) found that it was not possible to differentiate emigration from mortality and that the overall survival rate may not be dissimilar from that of E. orbicularis. Sexual maturity is reached at 5-6 years in males and 7-8 in females (Ottonello et al. 2021a).

Available distribution data collected over the years suggest that the species is in decline, mainly due to habitat conversion and degradation (Di Cerbo 2010, Ottonello et al. 2021a). However, the species can also make use of anthropogenic wetland habitats and is not a habitat specialist, so these apparent declines need additional studies in order to be confirmed. The degree of habitat loss, as a proxy for population decline, of this species over the past 48 years (the longest estimated three-generation length period) can not be estimated.

The geographical pattern of genetic diversity within the population was investigated across its entire distribution range using 16 microsatellite loci (Vamberger et al. 2015). They found geographically-based structuring of the studied subpopulations in five well-characterized clusters, supported by a moderate degree of genetic fragmentation, and proposed both natural and human-mediated habitat fragmentation as the cause.

In general, the ecology and the habitat use of E. trinacris is similar to that of the more intensely studied E. orbicularis. The species is associated with inland aquatic environments with standing or slow-running waters (Ottonello et al. 2021a). It inhabits a wide range of coastal and inland wetlands: small ponds and lakes both in open areas and woodlands, man-made reservoirs, marshes, slow-moving river sections, and peripheral ponds (Ottonello et al. 2021a). It is known even from very altered and suburban sites, and thus is apparently quite tolerant of habitat disturbance and can be considered, within its narrow distribution range, a habitat generalist (Ottonello et al. 2021a). However, it is not known whether the individuals observed in very altered sites are a sign of long-term stable occupancy, or are these observations of the last ‘walking dead’ residents or passage wanderers. The species estivates in hot summers, and in coastal areas the estivation period may extend for up to five months.

The Sicilian Pond Turtle is opportunist, generalist, and omnivorous, with the main prey type being aquatic invertebrates (Ottonello et al. 2021a). Males showed a wider dietary spectrum than females. Leaves and roots of aquatic plants are also eaten frequently, with fruits and seeds being consumed especially in springtime. Ottonello et al. (2021a) report that, by pooling all diet samples per time period, the diet composition varies remarkably among seasons, thus confirming the adaptable feeding strategy of this turtle species.

The estimated age of sexual maturity is 5-6 years for males and 7-8 years for females in the single demographically studied subpopulation. Mature females produce one or two clutches per year; clutches average 4.4 +/- 1.5 eggs, ranging from 2 to 8 (n=25). Hatchlings measure about 23 mm CL at a mean body mass of 3.4 +/-0.2 grams; males measure up to 156 mm SCL and 600 grams, while females reach a maximum size of 172 mm SCL and 900 grams body mass. Average and maximum longevity are not known for this species. The generation length for this species was estimated at 14-16 years (Ottonello et al. 2021a).

The species is threatened primarily by the loss of wetland habitat, and perhaps formerly by over-exploitation (Fritz et al. 2005). In southern Italy, 70-90% of the suitable wetlands were lost over the past century (Gasc 1997). It is unknown, however, if these threats impact E. trinacris at the global scale, whereas they are certainly detrimental at the local subpopulation scale. Studies on the effects of climate change on this species' distribution and abundance are needed.

The species may also be potentially impacted by recreational fisheries (incidental bycatch and ingestion/injury by fish hooks) (Vecchioni et al. 2020b), although the extent of this threat is not well documented. In their study of two subpopulations (one in a nature reserve, one not) in western Sicily, none of 120 wild individuals X-rayed had ingested hooks or other fishing gears, whereas 41 individuals received by rescue centres in Sicily had damage due to fishing hooks (Vecchioni et al. 2020b). That study focused on a subpopulation within a nature reserve where no recreational fishing is permitted legally, although illegal fishing is common, and nothing can be inferred about the potential impact of these fishing tools in non-protected waterbodies.

Ottonello et al. (2021b) found that the presence of introduced invasive freshwater fish Cyprinus carpio and Gambusia holbrooki resulted in significant differences in abundance, growth and reproductive output between subpopulations of the Sicilian Pond Turtle in waterbodies where the introduced freshwater fish are present or absent.

Introduced and reproducing subpopulations of Trachemys scripta (Liuzzo et al. 2020, Vecchioni et al. 2022a) potentially represent ecological competitors, and have the potential to introduce a range of diseases such as Ranavirus, mycoplasma, adenovirus and other parasites and pathogens. More studies are needed to understand the presence and impact of non-native freshwater turtles and their potential impacts on ecological competition, pathogens and parasites.

The species appears to have occurred in trade (at least in the past, as evidenced by introduced occurrence in Germany and Italy), although it is legally protected at the national level. Currently it seems that the trade is really scarcely relevant for this species. The species was certainly consumed by people till several decades ago, but this use is not ongoing nowadays.

The species was first assessed for the IUCN Red List as Data Deficient (DD) (assessed in 2004 but not published until 2009; van Dijk 2009). However, the species was more recently considered as Least Concern (LC) on the TFTSG Provisional Red List (Rhodin et al. 2021). The species was assessed as Endangered (EN A2c) on the Italian Red List (Andreone et al. 2013), based on an assumed population decline over the past three generations due to a drastic reduction of suitable habitats (reclamation of wetlands). Vamberger et al. (2015) and Vecchioni et al. (2020a) stressed the importance of defining independent Management Units in the species, and at least five management units for E. trinacris were defined.

As a former component of Emys orbicularis, it is assumed to be included in Appendix II of the Bern Convention (European Wildlife and Natural Habitats) and in Annexes II (conservation requires special area designation) and IV (in need of strict protection) of the European Union Habitats Directive (92/43/CEE). The species is listed in the designations of 69 Natura 2000 sites (EEA 2023) across the island. Conservation actions are underway that benefit this species, for example at the Laghetti di Preola e Gorghi Tondi Natura 2000 site (ITA010005, ITA010031), where research and habitat protection (land purchase, nesting habitats and water management) have been undertaken (D. Ottonello pers. comm. 2023).

The species has the potential of becoming a flagship species for wetland conservation in Sicily.

Because of its restricted geographical distribution, a recommendation of strict national and international protection of E. trinacris and its habitats has been made. Existing protections, including a ban on capture for trade, has been largely achieved so far but it must be continued. Safeguarding remaining habitat is essential, and management of non-native invasive species (including Trachemys and other alien turtles, Cyprinus and other introduced fish species) is desirable, particularly in protected area wetlands. Awareness among recreational fishermen of the risk and impact of hook ingestion by turtles should be generated. Preventing genetic pollution from the release to the wild of Emys orbicularis in Sicily (Vecchioni et al. 2022b) is essential, and further taxonomic studies are desirable to further clarify the taxonomic status of the taxon.

Vamberger et al. (2015 proposed that the five genetically-differentiated clusters be considered as independent Management Units.