A Comparative Morphometric Study on Odontobuthus bidentatus and Odontobuthus doriae (Scorpionida: Buthidae) in Iran

1. Introduction

Till now, 66 species of scorpions belonging to three scorpion families of Buthidae, Hemiscorpiidae, and Scorpionidae have been identified in different localities of Iran. Scorpionism is a major public health concern and can sometimes be fatal. Annually, about 40-50000 cases of scorpionism are reported in Iran. Among the Iranian scorpion fauna, the most medically important species include Mesobuthus eupeus, Mesobuthus phillipsii, Androctonus crassicauda, O. doriae, Hottentotta saulcyi, Hottentotta zagrosensis, Compsobuthus matthiesseni, and Hemiscorpius lepturus ( 1 - 15 ).

The Odontobuthus spp. are among the burrowing scorpion species in Iran, and they mostly burrow to find shelter and protection against predators. The genus Odontobuthus (Family Buthidae) is comprised of four species in Iran, namely Odontobuthus bidentatus, Odontobuthus brevidigitus, Odontobuthus tirgari, and Odontobuthus tavighiae. Odontobuthus doriae has a wider distribution range from the west to central parts of Iran at higher altitudes. Odontobuthus brevidigitus is commonly distributed in the Zagros mountain ranges in the West, whereas O. tavighiae has only been reported in the southern region of Iran (Hormozagan Province). Odontobuthus tirgari is mostly observed in the eastern region of Iran. Epidemiologically, O. doriae is considered among the scorpions of medical importance in Iran, and morphologically, it is similar to O. bidentatus ( 16 - 18 ). There are no morphometric data on the comparison between these two species; therefore, comparing morphometric measurements between these species can be of great help in accurate identification of these scorpion species, providing the basis for the production of appropriate regional antivenom. In light of the aforementioned issues, the present study aimed to analyze and compare basic morphometric measurements of O. doriae and O. bidentatus.

2. 2. Materials and Methods

2.1 Study Area and Specimens Collection

The scorpion specimens were captured from Tehran, Markazi, Khuzestan, and Kerman Provinces between 2014-2015 using the digging and ultraviolet methods (Figure 1). The specimens were kept in plastic bottles containing 75% ethylic alcohol and transported to the Medical Entomology lab of the School of Public Health, Tehran University of Medical Sciences. Valid Iranian scorpion identification key (Farzanpay 1987) was used to identify the scorpion species ( 19 ). Following scorpion identification and sex determination, two species (O. doriae and O. bidentatus) (Figure 2) were selected for further morphometric studies. Only females were included in this study, and 55 morphological characters and ratios were examined according to recommended nomenclature by Stahnke ( 20 ).

Figure 1. Provinces of scorpion collection sites (Odontobuthus doriae was collected from Tehran and Markazi Provinces, Odontobuthus bidentatus was collected from Khuzestan and Kerman Provinces)

Figure 2.AOdontobuthus bidentatus, B:Odontobuthus doriae2.2 Morphological Characters

The 55 morphological characters and ratios examined in the current study were as the following: the length of body, Chelicerae length, width, and height, length and width of chelicerae, distance between median eyes, distance between median and lateral eyes, distance between median eyes and the anterior margin of the carapace, length of carapace, anterior and posterior width of carapace, height of carapace, length, width, and height of trochanter, length and width of the trochanter, length, width, and height of femur, length of femur/width of the femur, length, width, and height of patella, length of patella/ width of the patella, length of manus, length, width, and height of chela, length of chela/width of chela, length of I, II, III, IV, and V, length of metasomal segment I, II, III, IV, and V/ width of the metasomal segment I, II, III, IV, and V, length, width, and height of telson, length of pectines moveable finger, length of the fixed finger, length, width, and height of metasomal segments ( 15 ).

2.3 Data Analysis

These measurements were carried out using calipers and a stereomicroscope equipped with a caliper (accuracy to one-hundredth of a millimeter), and the data were transferred into an excel sheet for each species. Independent samples T-test was performed in SPSS software (version 24) to compare the studied characters between these two species (Table 1).

3. Results

A total of 32 scorpion specimens, including 16 specimens of O. doriae and 16 specimens of O. bidentatus, collected from the aforementioned provinces were examined. The following morphological measurements from the two scorpion species were significantly different (P<0.05): body length, length and width of chelicerae, the distance between median eyes and the anterior margin of the carapace, carapace length, anterior and posterior width of carapace, trochanter width, length and width of the femur, patella length, length and width of chela, the width of metasomal segment II, III, length and width of metasomal segment IIII, length and width of telson, length of telson/width of telson*, and pectin length.

In almost all cases, the mean value of each measurement from the morphological characters was greater in O. doriae, as compared to that in O. bidentatus. These two burrowing scorpions are very similar to each other, except for one morphological character: the number of lateral lobes on the anal arch. Odontobuthus doriae has two lateral lobes on the anal arch, whereas O. bidentatus has three lateral lobes on the anal arch. The results of the present study pointed out that O. doriae has a larger body size than O. bidentatus: mean body lengths were 71.57 and 59.60 mm for O. doriae and O. bidentatus, respectively.

In the study area, the prosoma of O. doriae was wider than that of O. bidentatus: The mean values of anterior width of the carapace were reported as 4.45 and 5.25 mm for O. bidentatus and O. doriae, respectively, and the mean values of posterior width of the carapace were 8.59 and 9.76 mm for O. bidentatus and O. doriae, respectively. In the present study, O. doriae had a wider metasoma in some segments, compared to O. bidentatus, and the telson of O. doriae (mean telson length and width: 8.33 and 3.80 mm, respectively) was bigger than that of O. bidentatus (mean telson length and width: 6.35 and 3.28 mm, respectively).

4. Discussion

The present study was conducted to compare 55 morphological characters and ratios between O. doriae and O. bidentatus, both of which belong to the family Buthidae. Odontobuthus bidentatus, previously known as O. odonturus, is mainly distributed in southern Iran. Odontobuthus doriae has a wider distribution extending from the west to the central part of Iran at higher altitudes, such as mountainous areas ( 19 ). Numerous morphometric studies have previously been conducted on scorpion species identification ( 21 - 26 ). Nonetheless, there is no morphometric study comparing O. doriae and O. bidentatus in Tehran, Markazi, Khuzestan, and Kerman provinces in Iran.

In the current study, almost all the morphological measurements from O. doriae and O. bidentatus were significantly different (P<0.05). The mean measurements of the morphological characters of O. doriae were larger, as compared to those of O. bidentatus. Molecular and morphometric studies on the genus Odontobuthus performed in Iran by Mirshamsi demonstrated that Odontobuthus tirgari was morphologically different from O. doriae and O. bidentatus ( 16 ). On the other hand, unlike the results of the present study, Odontobuthus doriae scores were lower than the other species. This discrepancy can be ascribed to differences in collection sites. In the current study, O. doriae was collected from Tehran and Markazi provinces, whereas O. bidentatus was collected from Khuzestan and Kerman Provinces.

It is worth mentioning that the geographical populations of O. doriae and O. bidentatus that are distributed in different localities in Iran ( 10 , 13 , 17 - 19 , 27 - 33 ) are different in body size. In a morphometric study on O. bidentatus carried out by Ahmadi, Vazirianzadeh ( 34 )in Khuzestan province, the pectines in the males were longer and more, as compared to those in the females. In the abovementioned study, the mean total body length of O. bidentatus was 74 mm; nonetheless, in the present study, it was 71.57 mm. This small difference in mean total body length between the present study and that of the research by Ahmadi et al. can be attributed to measurement errors.

In another study which was also conducted in Khuzestan province, the mean total length of O. bidentatus was reported as 77 mm ( 35 ), which is by far larger than the measurement in the current research. Regarding this finding, it can be stated that minor changes in the habitats of scorpions can affect their body size. Therefore, we reiterate that the results of the present research are only reliable in our study area. In another study, the mean total length of O. tavighiae was 49.8 mm ( 34 ). Based on the results of the present study, it can be concluded that total body size can be used to distinguish O. tavighiae from O. bidentatus in our study area.

5. Conclusion

Odontobuthus doriae and O. bidentatus, both belonging to the family Buthidae, have triangle sternum and are morphologically very similar to each other. They are categorized as burrowing scorpions. They have similar coloration and carination, making it difficult to distinguish between them. The findings indicated that there are significant (P<0.05) distinguishing morphological characters between these two species, especially the mean total body length, as well as the length of carapace, chelicerae, metasoma, and telson. The mean measurements of all morphological characters in O. doriae were greater than those of O. bidentatus in our study area. The morphological measurements demonstrated a clear distinction between O. doriae and O. bidentatus in our study area; therefore, they can be used as morphological identification keys for distinguishing between these two species. It is recommended that morphometric studies be conducted on the specimens of these species in other parts of Iran to clarify the differences between them.

Authors' Contribution

M. F., A. M., and J. R. designed the study, M. M. B. did the morphometric analyses and prepared the manuscript, and S. N. contributed to writing the manuscript and specimen identification.

Ethics

All the procedures were approved by the ethics committee of the Research Deputy of Tehran University of Medical Sciences (TUMS) Iran.

Conflict of Interest

The authors declare that they have no conflict of interest.

Grant Support

This study was supported by the Research Deputy of Tehran University of Medical Sciences (TUMS) Iran (project no. 92-01-27-20619).

Acknowledgement

We gratefully acknowledge the personnel of Razi Vaccine and Serum Research Institute, Department of Venomous Animals and Toxins for their invaluable help.

References

1. Bavani MM, Rafinejad J, Hanafi-Bojd AA, Oshaghi MA, Navidpour S, Dabiri F, et al. Spatial Distribution of Medically Important Scorpions in North West of Iran. J Arthropod Borne Dis. 2017; 11(3):371-82.
2. Dehghani R, Fathi B. Scorpion sting in Iran: a review. Toxicon. 2012; 60(5):919-33.
3. Dehghani R, Haghi F, Mogaddam M, Sedaghat M, Hajati H. Review study of scorpion classification in Iran. J Entomol Zool Stud. 2016; 4(5):440-4.
4. Dehghani R, Rafinejad J, Fathi B, Shahi MP, Jazayeri M, Hashemi A. A Retrospective Study on Scropionism in Iran (2002-2011). J Arthropod Borne Dis. 2017; 11(2):194-203.
5. Firoozfar F, Saghafipour A, Vatandoost H, Mohammadi Bavani M, Taherpour M, Jesri N, et al. Faunistic Composition and Spatial Distribution of Scorpions in North Khorasan Province Northeast of Iran. J Arthropod Borne Dis. 2020; 13
6. Firooziyan S, Sadaghianifar A, Rafinejad J, Vatandoost H, Bavani MM. Epidemiological Characteristics of Scorpionism in West Azerbaijan Province, Northwest of Iran. J Arthropod Borne Dis. 2020; 14(2):193-201.
7. Gholizadeh S, Lalehzari E, Bavani MM, Hosseini A, Khalkhali HR, Rafinejad J. Bioecology and scorpion envenomation in Ramshir district, Khuzestan Province, southwestern Iran. Appl Entomol Zool. 2016; 51(1):37-42.
8. Kovařík F, Yağmur E, Moradi M. Two new Hottentotta species from Iran, with a review of Hottentotta saulcyi (Scorpiones: Buthidae). Euscorpius. 2018; 2018:1-14.
9. Mohammadi BM, Saeedi S, Saghafipour A-M. Spatial Distribution of Medically Important Scorpions in Iran: A Review Article. Shiraz Shiraz Med. 2020; 22(5):e102201.
10. Motevalli Haghi F, Dehghani R. A Review of Scorpions Reported in Iran. J Mazand Univ Med Sci. 2017; 27(151):213-26.
11. Rouhullah D, Esmail C, Nedasadat S-B, Elahe C, Maedeh G-G. A Review on Scorpionism in Iran. J Arthropod Borne Dis. 2018; 12(4)
12. Sanaei-Zadeh H, Marashi SM, Dehghani R. Epidemiological and clinical characteristics of scorpionism in Shiraz (2012-2016); development of a clinical severity grading for Iranian scorpion envenomation. Med J Islam Repub Iran. 2017; 31:27.
13. Sedaghat MM, Salahi-Moghaddam A, Dehghani R. Mapping the Distribution of some important Scorpions Collected in the Past Five Decades in Iran. J Army Univ Med Sci. 2011; 9:285.
14. Sofizadeh A, Kalteh EA, Saeedi S, Mohammadi Bavani M. A New Study of the Species Composition of Scorpions in Golestan Province, Northeast of Iran. Punjab Univ J Zool. 2021; 36
15. Stockmann R, Flay N. Scorpions of the World. 2010.
16. Azghadi S, Mirshamsi O, Navidpour S, Aliabadian M. Scorpions of the genus Odontobuthus Vachon, 1950 (Scorpiones: Buthidae) from Iran: Phylogenetic relationships inferred from mitochondrial DNA sequence data. Zool Middle East. 2014; 60(2):169-79.
17. Dehghani R, Kassiri H. Geographical Distribution of Scorpion Odontobuthus doriae in Isfahan Province, Central Iran. J Arthropod Borne Dis. 2017; 11(3):433-40.
18. Mirshamsi O, Azghadi S, Navidpour S, Aliabadian M, Kovarik F. Odontobuthus tirgari sp. nov. (Scorpiones, Buthidae) from the eastern region of the Iranian Plateau. Zootaxa. 2013; 3731:153-70.
19. Farzanpay R. Knowing scorpions. No. 312, Biology 4. Central University Publications, Tehran. [in Farsi with Latin index]. 1987.
20. Stahnke HL. Scorpion Nomenclature And Mensuration. Entomol News. 1970; 81:297-316.
21. Abdel-Nabi I, McVean A, Abdel Rahman M, Omran MA. Intraspecific diversity of morphological characters of the burrowing scorpion Scorpio maurus palmatus (Ehrenberg, 1828) in Egypt (Arachnida: Scorpionida: Scorpionidae). Serket. 2004; 9:41-67.
22. Harington A. Variation in the Scorpion Parabuthus villosus (Peters) (Scorpiones, Buthidae): A Case of Intermediate Zones. J. Arachnol. 1983; 11:393-406.
23. Karataş A, Karataş A. Mesobuthus eupeus (C.L. Koch, 1839) (Scorpiones: Buthidae) in Turkey. Euscorpius. 2003; 2003:1-6.
24. Mongiardino Koch N, Ceccarelli FS, Ojanguren-Affilastro AA, Ramirez MJ. Discrete and morphometric traits reveal contrasting patterns and processes in the macroevolutionary history of a clade of scorpions. J Evol Biol. 2017; 30(4):814-25.
25. Ozkan O, Adiguzel S, Kar S. Parametric values of Androctonus crassicauda (Oliver, 1807)(scorpiones: buthidae) from Turkey. J Venom Anim Toxins. 2006; 12(4):549-59.
26. Taravati S, Darvish J, Mirshamsi O. Geometric morphometric study of twospecies of the psammophilous genusErodiontes (Coleoptera: Tenebrionidae)from the Lute desert, Central Iran. Iran. J Anim Biosyst. 2009; 5:81-9.
27. Dehghani R, Moabed S, Kamyabi F, Haghdoost AA, Mashayekhi M, Soltani H. Scorpions Fauna of Kerman Province-IRAN. J Kerman Univ Med. 2008; 15(2):172-81.
28. Mirshamsi O, Sari A, Hosseinie S. History of study and checklist of the scorpion fauna (Arachnida: Scorpiones) of Iran. Prog Mol Biol. 2011; 1:16-28.
29. Mozaffari E, Sedaghat M, Dehkordi A, Akbarzadeh K. Bidiversity and species composition of scorpions (Arachnida, Scorpiones) in Ilam County, Iran. J Appl Sci. 2013; 9(9):5412-8.
30. Navidpour S, Studies B. An annotated checklist of scorpions in south and southwestern parts of Iran. Int J Fauna Biol. 2015; 2:09-15.
31. Nejati J, Mozafari E, Saghafipour A, Kiyani M. Scorpion fauna and epidemiological aspects of scorpionism in southeastern Iran. Asian Pac J Trop Biomed. 2014; 4(1):217-21.
32. Sharifinia N, Gowhari I, Hoseiny-Rad M, Aivazi A. Fauna and geographical distribution of scorpions in Ilam Province, South Western Iran. J Arthropod Borne Dis. 2017; 11(2)
33. Yağmur E. Scorpion Fauna of Zanjan Province, Iran (Arachnida: Scorpiones). J Appl Biol. 2015; 9(1):11-4.
34. Ahmadi. A morphometric study of odonthubutus bidentatus (scorpionida: buthidae) and it&#039;s dimorphism in khuzestan a sw province, iran. J Exp Zool India. 2014; 19(1):1567-70.
35. Ghassemi M, Dalimi A, Navidpour S. Morphomctric study on two different borrowing species of liuthidae scorpions from khoozestan province, Iran. J Anim Vet Adv. 2015; 14:263-7.