An annotated list of the reptiles of the highland grassland of Tandilia Mountains, Argentina

The study of biodiversity is a fundamental step to develop conservation strategies. Reptile populations are immersed in a global crisis, due to anthropic disturbances. Almost the entire Pampa ecoregion in Argentina was modified for agricultural and livestock activities, the only remnants of mountain native grasslands in Buenos Aires province being the Tandilia and Ventania mountain systems. Ventania reptiles have been exhaustively researched in last years, while Tandilia counts with fewer studies. We presented an actualized reptiles list of the Tandilia Mountain System. We used five data sources to collect presence records: literature, fieldwork, museum collection, citizen science, and a online database. The composition of reptiles from the Tandilia Mountain range includes 26 species in 12 families. Due to the presence of several endemic reptiles, and the representativeness of more than half of the reptiles of Pampa Ecoregion, Tandilia would be useful to determine conservation priority areas to conserve the native grassland and their reptile fauna.


Introduction
Biodiversity knowledge of a specific area is a fundamental step to assess and plan conservation actions against current local and global threats (Ringuelet and Aramburu 1957;Krebs 2008). Reptiles are immersed in a global crisis of biodiversity, which expresses in the decline and local extinctions of many species, mainly caused by such anthropic disturbances as habitat loss and fragmentation (Gibbons et al. 2000). Most species of reptiles are sedentary and they have a low capacity for movement, so they have limited capacity to move among patches of habitat (Pianka 1986;Sarre 1995;Fischer et al. 2004Fischer et al. , 2005Vitt and Caldwell 2014). Thus, reptiles may be particularly affected by the effects of habitat loss, fragmentation, and degradation (Driscoll 2004;Brown et al. 2008).
The majority of the Pampa ecoregion, one of the largest grasslands of the world, was replaced by agriculture and forestry (Isacch et al. 2017;Herrera et al. 2019;Nanni et al. 2020). Two mountain ranges systems emerge in the extremely flat Pampa grasslands: the Tandilia and the Ventania. These mountains, acting as a refuge for native grassland species, including several endemic amphibians and reptiles (Isacch et al. 2017;Herrera et al. 2019;Vera et al. 2020;Martínez Aguirre et al. 2021). Currently, both mountain systems are severely fragmented, and the native highland grassland is surviving in a few thousands of small remnants, harboring an outstanding biodiversity (Schwerdt et al. 2014;Martínez Aguirre et al. 2021). The biodiversity of the Tandilia Mountain System remnants is facing a combination of threats . Invasive woody plant species are replacing the grassland and homogenizing the landscape (Zalba and Villamil 2002;Márquez et al. 2019). The overgrazing, quarry activities, and the urban growth over the mountains accentuate the degradation, fragmentation, and isolation of grassland remnants (Cepeda et al. 2013).
The reptiles of Ventania Mountain System are well known, and many herpetological studies have been carried out there (Koslowsky 1895;Couturier and Grisolía 1989;Viñas et al. 1989;Di Pietro et al. 2012, 2020aDi Pietro 2016). However, the Tandilia Mountain System has been poorly explored in search of reptiles. The reptiles of Tandilia have been systematically surveyed in a few remnants at the southeast range by Vega and Bellagamba (1990). A couple of references for central and northern range were reported in general reptile literature for Buenos Aires province and only some zoogeographic notes and occasional records reported specific localities and voucher specimens (Nágera 1915;Gallardo 1977;Cei 1993;Di Pietro et al. 2010, Vera et al. 2020  . These two lizards have been described in the southern range of the Tandilia Mountain (Vega et al. , 2018, with scarce records of L. tandiliensis in the central range. The presence of these endemisms and other reptiles in the rest of the Tandilia Mountain range are still unknown. Studying biodiversity in large-scale patterns requires a vast amount of data to be collected across different habitats and locations over several years or decades (Bonney et al. 2009). This is very expensive in terms of time, money and human resources. Citizen science is a research method that enlists the public to gather scientific information and allows collecting data in large temporal and spatial scales (Bhattacharjee 2005;Cooper et al. 2007). Local citizen science projects have been remarkably successful in advancing scientific knowledge (Bonney et al. 2009). Since 2019, a local citizen science project, Reptiles de Tandilia, has been running in the Tandilia region.
In this work, we compiled and described the composition of the reptiles of the Tandilia Mountain System as baseline information to develop conservation strategies of this unique and endangered highland grassland in Argentina. Additionally, we provided the conservation status of each species and a qualitative resume of habitat use.

Study area
The Tandilia Mountains is located in the center of Buenos Aires province, Argentina. These mountains are the most ancient in Argentina, dated in 2200 m.y. and are composed of igneous-metamorphic rocks covered by loess (Teruggi and Kilmurray 1980;Dalla Salda 1999). The Tandilia Mountains emerges along 350 km and covers 12.314 km 2 (Dalla Salda et al. 2006). The maximum height (524 m a.s.l.) is in Cerro la Juanita in Tandil locality. The average temperature is 21 °C in the warmest month and 6.3 °C in the coldest month. The 850 mm average annual rainfall shows two peaks, one in autumn and another in spring (Valicenti et al. 2010).
Because of their biodiversity and endemisms, the Tandilia Mountain System is considered as a Valuable Grasslands Areas for South America (Bilenca and Miñarro 2004). Unfortunately, only 0.07% of 12,314 km 2 of the Tandilia Mountain System is under a protection category with three protected areas covering 8.8 km 2 , viz. the Reserva Natural de Objetivo Mixto Boca de las Sierras (5.4 km 2 ), Reserva Natural Sierra del Tigre (1.2 km 2 ) and Reserva Natural Privada Paititi (2.2 km 2 ).

Data Source
We combined the records of reptiles in the Tandilia highlands, which were available at museum collections, online biodiversity databases, scientific literature, and the citizen science project Reptiles de Tandilia, with the records of an extensive fieldwork campaign. We followed the IUCN conservation status from each species, and the Argentinean National Red List Giraudo et al. 2012;Prado et al. 2012). We followed Uetz et al. (2021) for the nomenclature and systematics of the lizards and amphisbaenians, and Williams et al. (2021) and Melo-Sampaio et al. (2021) for the snakes.
We carried out fieldwork during the spring and summer, from September 2019 to March 2020 in the following sites ( . Samples consisted of visual encounter surveys searching in all habitat types, on transects of 500 meters long and 30 meters wide tracked by three observers. Surveys were performed between 9:00-12:00 hours and 13:00-16:00 hours during 42 days, and between 18:00 and 22:00 hours over the course of 11 days (total of 296 hours) in eight campaigns, each one with a five-day average. Also, we actively searched under logs, rocks, and other structures as wood and firewood to find underground or sheltered species. We recorded the location (with GPS Garmin eTrex 20) of each specimen and we took at least one photograph. Most of the specimens were released and only a few of them were collected and deposited in the Herpetological Collection of Museo de La Plata (MLP, see Appendix 1). The collection permit was provided by Dirección de Flora y Fauna de la Provincia de Buenos Aires (Permit number: 2019-16058740-GDEBA-DFYFMAGP).
In addition, we inspected voucher specimens in the herpetological collection of MLP, Argentina. We searched for records in three online biodiversity databases: Ecoregistros, iNaturalist and the Argentina biodiversity database (Sistema Nacional de Datos Biológicos, SNDB). Ecoregistros and iNaturalist are web platforms where users upload photographic records of wildlife observations. We inspected all records and we selected those where the photographs allowed us an unambiguous identification of the reptile species. The SNDB encompasses the main museum collections of Argentina. We compared our review of the specimens at the Museo de La Plata, and we found no differences with the records values in the SNDB. Then, we assumed that something similar must be occurring with the specimens reported by the Museo Argentino de Ciencias Naturales (MACN) collection in the SNDB.
We also collected data on reptile presence through the citizen science project Reptiles de Tandilia. This project was specifically created to collect data about reptiles from the local people of the Tandilia mountain range. We talked with local people and explained to them how to collect data on reptiles through photographs and videos and which data are relevant to the research (i.e., date, hour, locality, and geographic coordinates). Then, they sent the records to our social networks and we revised each record. We helped people to identify reptile species and gate the records in a database. We collected and included in this study data from September 2019 to November 2020.
Since the habitats of Tandilia and Ventania highland grasslands are similar, we followed the categories proposed by Di Pietro et al. (2020b) for habitat description and classification. We used only the data from the fieldwork since almost all the other sources of records do not have habitat description. The main habitats' classes of the mountain range are grasslands, rocky outcrops, and water bodies. The native grasslands present various microhabitats: a) dense grasslands, if they totally cover the area, b) open grassland, where the reptiles were found in a substrate of grassland and ground, c) shrubby grasslands, and d) under rocks immersed in grassland habitat. The rocky outcrops contain two types of microhabitat: a) loose rocks above rock substrate, and b) large blocks of rocks where the animals have been found basking or active. The water bodies include two microhabitats: a) stream edge and b) stream watercourse. The water bodies, in coarse-scale were mostly dry during the spring and summer.
Citizen Science.
The habitat type where each species of reptile was found is indicated in Table 1. The habitat with the highest richness is grassland, containing the 88.2% of the species of Tandilia. The rocky outcrops contain 29.4% of the species. Also, 17.6% of the species are present in both grassland and rocky outcrops.

Discussion
We conducted an extensive review of museum collections, databases, and literature, and we included our fieldwork observations, to compile the most complete list to date of the reptile species inhabiting the Tandilia Mountains. This region sustains more than half (53%) of the species reported for the Pampa ecoregion (e.g, Koslowsky 1896; Ringuelet and Aramburu 1957;Gallardo 1966Gallardo , 1967Gallardo , 1977Tiranti and Ávila 1997;Arzamendia and Giraudo 2002;Giraudo and Scrocchi 2002). In Tandilia Mountains would be surviving the 50% of amphisbaenians, 72% of lizards, 54% of snakes, and 33% of turtles of the Pampa Ecoregion in Argentina. Moreover, the Tandilia reptile richness represents the 44% of the reptiles mentioned in Buenos Aires province, including the 43% of snakes, 68% of lizards, 66% of amphisbaenians, and 14% of turtles Giraudo et al. 2012;Prado et al. 2012). Nágera (1915) and Gallardo (1977) cited Cnemidophorus lacertoides (Duméril & Bibron, 1839) for Sierras Bayas and Sierra de la China respectively. However, these citations do not mention reference material. Based on molecular and morphological analyses Cabrera et al. (2019) reviewed their taxonomic status and described the species as Contomastix celata. This species is endemic to Argentina, occurring in the highlands of Córdoba and Ventania. Due to the lack of specimens in collections from Tandilia, we are not capable of review material and determine the taxonomic identity of the cited specimens by Nágera (1915) and Gallardo (1977). Therefore, we assume that the species cited would be Contomastix celata.
According to the Argentine Red List, the Tandilia Mountains are the refuge of 33% of threatened reptile species inhabiting the Pampa grassland. Habitat fragmentation and degradation of native grasslands are the main threats of the three threatened reptile species (Liolaemus tandiliensis, Pseudablabes agassizii and Tomodon ocellatus) of Tandilia Mountains (Etchepare et al. 2012a, b;Kacoliris 2016). Even uncategorized, due to their restricted range, the recently described microendemic lizard (Liolaemus absconditus), would be a fourth threatened species of Tandilia highland grassland. Also, Cabrera et al (2019) indicated that due to the restrictive area, the status of Contomastix celata should be carefully analyzed in future evaluation.
We increased the known range of some species in the Tandilia Mountains. In the case of Phalotris bilineatus (Duméril, Bibron & Duméril, 1854), we found the first record in the northwest of the Tandilia system (i.e.; Cerro Largo, Sierras Bayas, Olavarría department); and for Tomodon ocellatus, we reported the southernmost record for the specie in Buenos Aires province. Homonota williamsii also extends their geographic distribution now present in Ventania and Tandilia Mountains. On the other hand, some reptile species seem to be rare or scarce in Tandilia. Four lizards (Aspronema dorsivittatum (Cope, 1862), Cercosaura schreibersii Wiegmann, 1834, Contomastix celata, and Stenocercus pectinatus (Duméril & Bibron, 1835)) and one snake (Psomophis obtusus (Cope, 1863)) species have few records, and we failed to find them during fieldwork. Although some authors have reported the presence of Stenocercus pectinatus in highland grasslands, the last known record in Tandilia Mountains is from 1915 (Holmberg 1884;Nágera 1915). Further surveys are needed to confirm the current presence of these species of reptiles in the region.
In the cases of turtles, they could be arriving from the stream Arroyo Tapalqué, where at least two specimens were collected (MACN-2239; MACN-785). We also consider the presence of these turtles could be associated with human translocation events, since they are out of the core distribution (Sánchez et al. 2019).
The Tandilia Mountains sustains a large number of Pampa reptile species, including threatened and endemic ones. The region urgently needs effective natural protected areas (Bilenca and Miñarro 2004;Brown and Pacheco 2006). Even when more studies are needed to understand the reptile distribution in the highland grassland, this work could be a useful tool to identify conservation priority areas for native reptiles of Tandilia Mountains.

Acknowledgements
We would like to thank field assistants and collaborators (Agustina la liebre Cortelezzi, Florcita Dosil Hiriart, Gimena Pizzarello Milanese, Gonzalo Reuter, Habib Cata Delfino Ahumada, Marcos Cogno, Micaela Mardones, Natalia Moro, Pilar Plantamura, Scarlett Mendez Herrera and Tomás Martínez Aguirre) for their kind assistance and support during the fieldwork activities. We also appreciate the collaboration of Federico Juana (Estancia Las Mercedes), Paulo Mosca (Estancia Ninonil), and Tomas Pérez Marino (Estancia El Bonete) by allowing entrance to their properties. We thank all people participating in the citizen science project (Reptiles de Tandilia). We thank Claudio Barletta (Reserva Natural Sierra del Tigre), Esteban Sugasti (Reserva Natural Privada Paititi), and Flavio Maldonado (Bioparque La Máxima) for their attention and collaboration. We thank Darío H. Podestá for his help as photo editor. Xóchitl Yáoyotl made valuable suggestions for improving this manuscript. This study was supported by the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET PIP. 11220150100598CO), the Agencia Nacional de Promoción Científica y Tecnológica (ANPCYT, PICT 2015-2281), Neotropical Grassland Conservancy (STUDENT GRANT PROGRAM 2019). The Dirección de Flora y Fauna of the Buenos Aires Province gave us the necessary permits to perform this work. Finally, we greatly acknowledge the anonymous reviewers whose comments improved our work.