Morphological Anomalies, Asymmetries and Scars of Road Killed Dolichophis Caspius (Serpentes, Colubridae) from Romania
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Herpetozoa 33: 77–85 (2020) DOI 10.3897/herpetozoa.33.e51338 Dead snakes and their stories: morphological anomalies, asymmetries and scars of road killed Dolichophis caspius (Serpentes, Colubridae) from Romania George-Adelin Ile1, Alexandra-Roxana-Maria Maier1, Achim-Mircea Cadar1, Severus-Daniel Covaciu-Marcov1, Sára Ferenți1 1 University of Oradea, Faculty of Informatics and Sciences, Department of Biology; 1, Universității, Oradea 410087, Romania http://zoobank.org/87D6BBEA-AD05-4B5C-A60E-E2724DE941DA Corresponding author: Severus-Daniel Covaciu-Marcov ([email protected]) Academic editor: Günter Gollmann ♦ Received 20 February 2020 ♦ Accepted 2 April 2020 ♦ Published 14 May 2020 Abstract We analysed several morphological characters of 84 road-killed D. caspius individuals from different areas of southern Romania. Most presented asymmetries in the total number of temporal scales, the temporal row and the periocular and labial scales. Almost a quarter of snakes had scars, located especially on the head and tail; many individuals had multiple injuries. The lowest rate of individ- uals with scars was found in the area with the least anthropogenic impact (Danube Gorge). This finding suggests that, in other areas in Romania, the species is threatened and lives in less optimal conditions. The number of individuals with asymmetries and scars differed according to the populated region, sex or size class. Most of the individuals were killed in August, due to the large number of road-killed juveniles. Key Words asymmetry traits, conservation, environment, morphology, road mortality Introduction be employed as study material for feeding ecology (Dry- gala and Zoller 2013; Kolenda et al. 2019), phylogeog- As in many other species, snakes are in decline (Winne raphy (Grill et al. 2009; Horcajada et al. 2018), temporal et al. 2007; Reading et al. 2010; Graitson et al. 2019; trends in populations (Meek 2020) and faunistic studies Reading and Jofré 2020). One of the major threats for (Gonzáles-Gallina et al. 2016; Teodor et al. 2019). snakes is mortality from road traffic when making a road In Romania, the Caspian Whipsnake, Dolichophis crossing (Ciesiołkiewicz et al. 2006; Meek 2009, 2015; caspius Gmelin, 1789 is situated at the northern limit of Lutterschmidt et al. 2019). This factor affects not only its distribution range (Sillero et al. 2014). The species the common species (Borczyk 2004; Ciesiołkiewicz et al. is frequently found dead on roads, not only in Romania 2006), but also species of conservation interest (Rosen (Covaciu-Marcov and David 2010; Covaciu-Marcov et and Lowe 1994), endemic species (Santhoshkumar et al. al. 2012b; Sahlean et al. 2019), but in other regions (Tok 2016) or those situated at the limit of their range (Co- et al. 2011). It is a large species (Fuhn and Vancea 1961) vaciu-Marcov et al. 2012a). Road traffic does not only and, hence, corpses are easily noticeable from mov- impact snakes, but also other animals (Ashley and Rob- ing vehicles (Covaciu-Marcov et al. 2012b). In the last inson 1996; Glista et al. 2007; Baxter-Gilbert et al. 2015; two decades, we collected numerous D. caspius corpses Ciolan et al. 2017). The high number of mortalities from on different roads in Romania and accumulated a large different animal groups has permitted road mortalities to database. Thus, we used road-killed D. caspius to anal- Copyright George-Adelin Ile et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 78 George-Adelin Ile et al.: Morphological traits of road killed D. caspius from Romania yse various parameters of external morphology, such as scribed slightly differently by Fuhn and Vancea (1961) asymmetries, morphological anomalies or scars. In addi- and Kotenko et al. (1986) in D. caspius. In the temporal tion, we examined specimens for information on distribu- region, we considered two parameters: number of scales tion-dependent risk of mortality. connected to the parietal scale and the total number of Studies on asymmetry in reptiles are relatively new, scales situated between the parietal plate and the upper geographically biased and focus mainly on lizards and labials (Fuhn and Vancea 1961). We considered temporal less on snakes (Laia et al. 2015), although more recent scales as those that had more than 50% of their surface studies have appeared in literature (Brown et al. 2017; inside the temporal zone (delimited by the imaginary Löwenborg and Hagman 2017). In order to remedy this line drawn between the posterior corner of the parietal deficiency, studies on this topic are necessary, the more so scale and the posterior margin of the last upper labial because asymmetry seems to measure developmental sta- scale (Fig. 1A)). The temporal row was treated as in bility in stressful conditions (Laia et al. 2015). The main Brown et al. (2017). All scales around the eye (suboc- objectives were (1) to obtain meristic and metric data on ular, preocular, supraocular and postocular) were treat- morphology and compare these with existing data, (2) to ed as perioculars, as applied previously (Bellaagh et al. analyse asymmetries, anomalies and scars on the studied 2010). The scales around the mouth (upper labials and individuals and (3) to examine for inter-regional differ- lower labials) were treated as labials. The asymmetry ences in sex and size. was calculated as absolute value (|R-L|; R-right side, L-left side), a frequently-used parameter in asymmetry indices (Palmer 1994). The number of individuals with Methods asymmetry or multiple asymmetry, regardless of the trait of occurrence, was reported as a percent from data sub- We examined 84 D. caspius individuals, from almost all sets (sex, origin, size), similar to some asymmetry indi- over the territory occupied by this species in Romania, ces suggested by Palmer (1994), but separately for each except from the small area it populates in southern Mol- trait. We noted anomalies of abnormal scale division or dova (Sahlean et al. 2019). All snakes were found dead, union and presence of scars. These were divided into killed mostly by cars on roads or sometimes by local peo- scars on the head, body and tail (Frank and Dudás 2019). ple (Covaciu-Marcov and David 2010; Covaciu-Marcov Tail integrity was also examined. Measurements were et al. 2012b). Most were identified from a moving car at performed only when carcasses were in good condition. low speed. Some of the specimens had been preserved 20 Severely damaged individuals were analysed within the years previously, but most were collected between 2018 limits of possibilities. and 2019. For all snakes, we had information on the local- Using linear regression, we estimated the correla- ity, region and date of collection, except for two, in which tion between: size class and frequency of individuals we know only the geographic origin. They are deposited in with scars, size class and number of scars from each the scientific collection of the Department of Biology, Fac- size class, respectively, seasonal frequency and average ulty of Informatics and Sciences, University of Oradea. size of individuals. The Kruskal-Wallis test was used to Using the abundance of road-killed individuals, we es- estimate the differences between the number of ventral timated road mortality frequency with respect to period and subcaudal scales and their ratio (V/Scd) between the of the year. We calculated the frequency of occurrence two sexes; the number of ventral and subcaudal scales in each season according to size. We examined several and their ratio (V/Scd) between males and females from morphological traits, size (measured from head to tail), different categories (origin, size); number of individuals sex, head scalation, number of ventral and subcaudal with scars and number of scars on individuals accord- scales, as well as the presence/absence of anomalies or ing to the three subsets (sex, origin and size). The One- scars. Sex was determined by dissection, after the meth- way ANOVA test was used to estimate the differences od described by Pesantes (1994). Body-length was mea- amongst asymmetries (|R-L|) of the four traits over the sured with a ruler, an action made difficult by the reduced three data subsets (sex, origin and size). The Kolmogor- flexibility of snakes due to long-term preservation. The ov-Smirnov test was used to estimate data distribution snakes were divided into four size classes: 25–60 cm, before calculating asymmetry. In order to detect direc- 60–100 cm, 100–130 cm and 130–160 cm. Snakes were tional asymmetry, we used a one-sample t-test on signed divided into three groups, according to their geographical (R-L) differences between the right and left side of each origin, which were Dobruja, the Danube meadow and the trait. Calculations were made using the free PAST soft- Danube Gorge. Dobruja is situated south of the Danube, ware (Hammer et al. 2001). the other two regions lie north of the Danube. The Dan- ube meadow and the most part of Dobruja are lowland areas, with high anthropogenic disturbance and intensive Results agriculture. The Danube Gorge is a mostly natural low mountain area. The number and average size of snakes by month is pre- For head scalation, we examined all the bilateral fea- sented in Fig. 1. Strong negative correlation was observed tures (Fuhn and Vancea 1961). Temporal scales were de- between the number of individuals in each month and herpetozoa.pensoft.net Herpetozoa 33: 77–85 (2020) 79 Most of the corpses were in good condition, but in damaged corpses, only limited data were possible to ob- tain. The average number and range of ventral plates, subcaudal plates and the ratio between them (V/Scd) is presented in Table 1.