A new species of Androctonus from the Najd Plateau of Saudi Arabia (Scorpiones, Buthidae)

33 A new species of Androctonus from the Najd Plateau of Saudi Arabia (Scorpiones, Buthidae) Ersen Aydın Yağmur1* , Abdulaziz R. Alqahtani2* , Ahmed Badry3* 1 ManisaCelalBayarUniversity,AlaşehirVocationalSchool,Alaşehir,Manisa,45600,Turkiye 2 DepartmentofBiology,CollegeofScience,UniversityofBisha,P.O.Box551,Bisha61922,SaudiArabia 3 DepartmentofZoology,FacultyofScience,Al-AzharUniversity,NasrCity,P.O.Box:11751,Cairo,Egypt Correspondingauthor:ErsenAydınYağmur([email protected]) Copyright: © Ersen Aydın Yağmur et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0). Research Article Abstract A new scorpion species, Androctonus najdensis sp. nov., is described and illustrated from Saudi Arabia. It is compared with existing species from the Middle East and Iran, notably A. crassicauda (Olivier, 1807) and the recently described A. tihamicus Alqahtani, Yağmur & Badry, 2023. Molecular analysis using the COI mitochondrial gene revealed a genetic divergence of 7.0 to 11% between A. najdensis sp. nov. and A. crassicauda sensu lato samples from Saudi Arabia, Iraq, and Iran. The combination of molecular and morphological data supports the recognition of the Najd populations as a distinct species. Additionally, an identification key for Androctonus species in Iran and the Middle East is provided. Key words: COI, description, molecular phylogeny, morphology, phylogenetic analysis Introduction The genus Androctonus was established by Ehrenberg in Hemprich and Ehrenberg (1828) and is distributed across North Africa, the Middle East, and western Asia, with 54 valid species currently recognized (Fet and Lowe 2000; Abu Afifeh et al. 2025; Kovařík et al. 2025; Lowe 2025; Rein 2025; Yağmur et al. 2025c). This genus presents taxonomic challenges due to considerable intraspecific morphological and molecular variation (Ben Ali et al. 2000; Lourenço 2005, 2008; Lourenço and Qi 2006, 2007; Othmen et al. 2009; Alqahtani et al. 2022a, b). Scorpio crassicauda Olivier, 1807 was originally described from Kashan, Iran; Simon (1872) later transferred it to the genus Buthus, and Kraepelin (1891) subsequently classified it under Androctonus. Androctonus crassicauda sensu lato is widely distributed and known for its medical importance (Chippaux and Goyffon 2008; Alqahtani and Badry 2021). Its range extends from Sinai, Egypt, across the Arabian Peninsula and the Middle East to Iran (Crucitti 1999; Amr et al. 2021). The presence of A. crassicauda s.l. in Saudi Arabia has been reported by several authors (e.g., Vachon 1979; Hendrixson 2006; Al-Asmari et al. 2009, 2013; Alqahtani et al. 2019). Academic editor: José Antonio Ochoa Received: 24 June 2025 Accepted: 11 November 2025 Published: 3 December 2025 ZooBank: https://zoobank.org/ F7005FE6-20F5-4340-B3699F02B8AA28AE Citation: Yağmur EA, Alqahtani AR, Badry A (2025) A new species of Androctonus from the Najd Plateau of Saudi Arabia (Scorpiones, Buthidae). ZooKeys 1262: 33–59. https://doi. org/10.3897/zookeys.1262.163047 ZooKeys 1262: 33–59 (2025) DOI: 10.3897/zookeys.1262.163047 * These authors contributed equally to this work. 34 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia Alqahtani et al. (2022a, b, c) reported intraspecific morphological and molecular variation among A. crassicauda s.l. populations collected from different ecogeographical regions of Saudi Arabia, revealing the presence of three cryptic taxa within these populations. More recently, Alqahtani et al. (2023) described A. tihamicus Alqahtani, Yağmur & Badry from the Tihamah Plain, which had previously been considered part of A. australis. In Turkey, A. turkiyensis Yağmur, 2021 was described for the Şanlıurfa population; the author also designated a neotype for A. crassicauda s.s. from Kashan, Iran (Yağmur, 2021). Later, A. kunti Yağmur, 2023 was described from Iğdır Province, Turkey. Additionally, A. sumericus Khazali & Yağmur, 2023 from Dhi Qar Province, Iraq and A. ishtar Yağmur, Kachel, Al-Khazali, Al-Jubouri & Ali, 2025 from Dohuk and Nineveh provinces, Iraq, were subsequently described (Khazali and Yağmur 2023; Yağmur et al. 2025b). Recently, A. ammoneus Yağmur, Al-Saraireh & Abu Afifeh, 2025 and A. minaeus Abu Afifeh, Al-Saraireh & El-Hennawy, 2025 were described from Jordan (Abu Afifeh et al. 2025; Yağmur et al. 2025a), while A. ammophilus Lowe, 2025 and A. omanensis Lowe, 2025 were described from Oman and adjacent parts of Saudi Arabia and the United Arab Emirates (Lowe, 2025). However, the taxonomic status of the remaining Androctonus populations across the Middle East remains unresolved. In Iran, Barahoei et al. (2022) reviewed A. baluchicus (Pocock, 1900) and described A. sistanus Barahoei & Mirshamsi, 2022 from Sistan and Baluchistan Province. Later, Barahoei et al. (2025b) reviewed Androctonus populations across Iran, described A. rostami Barahoei, Mirshamsi, Amiri, Moeinadini & Rakhshani, 2025, and recorded A. sumericus. In a separate study, Barahoei et al. (2025a) examined populations from East Azerbaijan Province and recorded both A. kunti and A. turkiyensis. Very recently, Yağmur et al. (2025c) reviewed Androctonus populations in Iran and redescribed A. crassicauda (Olivier, 1807); they removed Prionurus crassicauda orientalis Birula, 1900 from synonymy and elevated it to species rank as A. orientalis (Birula, 1900), synonymized A. rostami with this species, and described A. azerianus Yağmur & Kovařík, 2025 (West Azerbaijan and Zanjan provinces), A. barahoeii Kovařík & Yağmur, 2025 (Bushehr, Chahar Mahal & Bakhtiyari, Fars, Ilam, Khuzestan, Kohgilouyeh & Boyer Ahmad, Lorestan, and Markazi provinces), A. caspius Kovařík, Yağmur, Fet & Lowe, 2025 (Alborz and Tehran provinces), and A. transcaucasicus Kovařík, Yağmur, Fet & Lowe, 2025 (Armenia, Azerbaijan, Iran: East Azerbaijan and West Azerbaijan provinces). Yağmur et al. (2025c) did not detect either A. kunti or A. turkiyensis but considered the presence of A. kunti in Iran plausible due to the absence of any significant geographical barriers. In this study, we examined the Androctonus population of the Najd Plateau, previously reported as A. crassicauda, and describe a new species, A. najdensis sp. nov. We compared this new species with A. ammophilus, A. omanensis, and A. tihamicus from Arabian Peninsula, as well as with A. ammoneus, A. azerianus, A. barahoeii, A. caspius, A. crassicauda (Olivier, 1807), A. ishtar, A. kunti, A. minaeus, A. orientalis, A. sumericus, A. transcaucasicus and A. turkiyensis from Iraq, Iran, Jordan, and Turkey. Materials and methods A total of 30 specimens of Androctonus najdensis sp. nov. were collected at night using ultraviolet light in Ha’il Province, Al Qassim, Riyadh, and the Eastern Province in 2021 (Fig. 17). The specimens were preserved in 96% ethanol. 35 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia Photographs were taken following the methodology described by Yağmur (2021). Trichobothrial nomenclature follows Vachon (1974), and morphological terminology follows Francke (1977), Stahnke (1971), and Hjelle (1990). The male holotype and a female paratype of A. najdensis sp. nov. were deposited in the Alaşehir Zoological Museum, Manisa Celal Bayar University, Alaşehir, Manisa, Turkey (AZMM), and the Al-Azhar University Zoological Collection (AUZC), Nasr City, Cairo, Egypt. The whole genomic DNA was isolated from nine samples collected from Najd Plateau from Hail, Riyadh, and Eastern provinces as previously reported by Alqahtani et al. (2022a). The sequences were edited using BioEdit v. 7.2.5 (Hall 1999). Additional sequences of Androctonus species were obtained from GenBank, as well as the sequence of Scorpio palmatus (AY156585.1) downloaded as the outgroup (Table 1). The sequences were aligned using ClustalW in Mega 11 (Tamura et al. 2021), and genetic distances (p-distances) for the entire data set were calculated using Mega 11 (Tamura et al. 2021). Table 1. List of Androctonus samples collected from Saudi Arabia used in this study and GenBank sequences, and museum number/accession numbers of COI marker used in the phylogenetic analysis. Species Location Region Country Lat., Long. Museum number / Accession number Reference A. crassicauda Arar Northern Borders Province Saudi Arabia 30.88, 40.87 2This study A. crassicauda Arar Northern Borders Province 30.88, 40.87 3This study A. crassicauda Arar Northern Borders Province 30.88, 40.87 4 This study A. crassicauda Dumah Al Jandal Al Jowf 29.84, 39.73 52 This study A. crassicauda Dumah Al Jandal Al Jowf 29.84, 39.73 42 This study A. crassicauda Dumah Al Jandal Al Jowf 29.84, 39.73 5 This study A. najdensis sp. nov. Hail Hail Province 27.37, 41.73 11 This study A. najdensis sp. nov. Hail Hail Province 27.37, 41.73 12 This study A. najdensis sp. nov. Hail Hail Province 27.37, 41.73 13 This study A. najdensis sp. nov. Buraydah Al Qassim 26.241, 43.94 1This study A. najdensis sp. nov Buraydah Al Qassim 26.241, 43.94 44A This study A. najdensis sp. nov Khurais Eastern Province 25.07, 48.02 16 This study A. najdensis sp. nov. Khurais Eastern Province 25.07, 48.02 41 This study A. najdensis sp. nov. Nazeem, east of Riyadh Riyadh 24.86, 47.06 9 This study A. najdensis sp. nov. Dhurma Riyadh 24.54, 46.17 16 This study A. crassicauda Mahneshan Mahneshan Iran 36.22, 47.86 MH352603 GenBank A. crassicauda Sari_Aghol Mahneshan 36.95, 46.93 MH352604 GenBank A. crassicauda Sahand-e Olya Mahneshan 36.77, 47.52 MH352605 GenBank A. crassicauda Darram Zanjan Province 37.02, 48.77 MH352606 GenBank A. crassicauda Chavarzagh Zanjan Province 36.80, 49.66 MH352607 GenBank A. crassicauda Taroom Sansooz 35.49, 48.20 MH352608 GenBank A. crassicauda Zanjan Zanjan Province 36.69, 48.50 MH352609 GenBank A. crassicauda Doasb Zanjan Province 36.16, 48.95 MH352610 GenBank A. crassicauda Daneshgah Zanjan Province 36.67, 48.50 MH352611 GenBank A. crassicauda Sardasht West Azerbaijan Province 36.14, 45.47 MK814934 Soltan et al. 2021 A. crassicauda Sardasht West Azerbaijan Province 35.68, 45.19 MK814933 Soltan et al. 2021 A. crassicauda – – Iraq 36.86, 42.98 MT229840 GenBank 36 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia Phylogenetic analyses of the COI data set (n = 34) were performed following Alqahtani and Badry (2020). Maximum-parsimony and neighbour-joining analyses were conducted with PAUP* v. 4 (Swofford 2001) using heuristic clustering based on TBR branch swapping. To assess the confidence within the nodes, 1000 bootstrapping replicates and random additions of taxa were used (Felsenstein 2002). The best-fit nucleotide evolution models were determined using MrModeltest v. 2.3 (Nylander 2004) based on the Akaike Information Criterion in PAUP* v. 4 (Swofford 2001). Bayesian inference (BI) was implemented using MrBayes v. 3.1.2 (Ronquist et al. 2012) for a million generations, and output parameters were plotted with Tracer v. 1.7 (Rambaut et al. 2018) to infer the geographic structure. Systematics Family Buthidae C. L. Koch, 1837 Genus Androctonus Ehrenberg, 1828 Androctonus najdensis sp. nov. https://zoobank.org/31020907-3DB3-4451-A3DE-3EC0047D4247 Figs 1–15; Table 2 Buthus crassicauda: Kraepelin 1899: 16–17. Androctonus crassicauda: Vachon 1966: 210; Vachon 1979: 31–34; Levy and Amitai 1980: 23–29; Al-Safadi 1992: 96; El-Hennawy 1992: 97, 101, 109–110; Fet and Lowe 2000: 72–73; Hendrixson 2006: 38–43; Al-Asmari et al. 2007: 836; Al-Asmari et al. 2009: 100; Al-Asmari et al. 2013: 5–7; Alqahtani et al. 2019: 21–22; Alqahtani et al. 2022a: 171–179; Alqahtani et al. 2022b: 1–18; Alqahtani et al. 2022c: 1–7. Type material. Holotype: • ♂ Saudi Arabia, Al Ahsa Province, Khurais, 25°04'12"N, 48°01'12"E, 449 m a.s.l., 10.III.2021, leg. A. Alqahtani (AZMM/Sco2021:25). Paratypes: • Saudi Arabia, Hail, Almada’n, 27°22'12"N, 41°43'48"E, 1038 m a.s.l., 1 ♀, 10.III.2021, leg. A. Alqahtani (AZMM/Sco-2021:25); • 5 ♂, 27°22'12"N, 41°43'48"E, 1038 m a.s.l., 10.III.2021, leg. A. Alqahtani (AUZC/Sco2021: 1103–1107). • Al Qassim, Buraydah 26°14'27"N, 43°56'24"E, 665 m a.s.l., • 2♀, 20.III.2021, leg. A. Alqahtani (AUZC/Sco-2021: 1108–1109). • 5 ♂, Hail, 27°22'12"N, 41°43'48"E, 1038 m a.s.l., 20.III.2021, leg. A. Alqahtani (AUZC/ Sco-2021: 1110–1114). • Riyadh; 2♀, Dhurma, 24°32'23"N, 46°10'11"E, 628 m a.s.l., 5.IV.2021, leg. A. Alqahtani (AZMM /Sco-2021: 1115–1116). • Dhurma, 24°32'23"N, 46°10'11"E, 628 m a.s.l., 4 ♂, 5.IV.2021, leg. A. Alqahtani (AUZC/ Sco-2021: 1117–1120). • Saudi Arabia, Al Ahsa Province, Khurais, 25°04'12"N, 48°01'12"E, 449 m a.s.l., 8♀, 10.IV.2021, leg. A. Alqahtani (AUZC/Sco-2021: 1121–1128). • Saudi Arabia, Al Ahsa Province, Khurais, 25°04'12"N, 48°01'12"E, 449 m a.s.l., 2 ♂, 10.IV.2021, leg. A. Alqahtani (AUZC/Sco-2021: 1129–1130). Diagnosis. Medium-sized scorpions. Average body length 73 mm in males and 79 mm in females. General coloration ranges from dark brown to blackish brown. Carapace carinae strong and bear coarse granules in males, and moderate granules in females. Intercarinal areas densely covered with coarse to medium granules in males, and with medium to minute granules in females. Chela manus smooth and lustrous; internal surface densely granular in males 37 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia and sparsely granular in females. Movable fingers of the pedipalps bear 16 rows of denticles, with external and internal accessory denticles and three distal granules. Fixed fingers bear 15 rows of granules, also with external and internal accessory granules and three distal granules. Trichobothrium et located between dt and est, and proximal to dt. Pectines bear 30–35 teeth in males and 23–28 in females. Tergites I–VI densely granular. All metasomal segments robust, longer than wide, and wider than deep. Segment V considerably more robust in males. Segments I–III have ten carinae, segment IV has eight, and segment V has five carinae. Dorsolateral carinae strong, with granules increasing in size posteriorly on segments I–IV; serrate on segment I, serrate to dentate or subdentate on segment II, and dentate on segments III–IV. On segment V, dorsolateral carinae strong, smooth anteriorly, and serrate posteriorly. Ventrolateral carinae strong on segments I–IV, with moderate and rounded granules on segments I and II, and coarse, rounded granules on segments III and IV. On segment V, ventrolateral carinae strong, bearing somewhat large granules that gradually and slightly increase in size posteriorly, without enlarged denticles. Description. (based on male holotype and female paratypes) Coloration (Figs 1, 2, 4, 6, 8, 10). Base coloration dark brown to blackish brown. Prosoma: carapace dark brown to dark reddish brown in males, and dark reddish brown in females; carinae and granules black. The area surrounding and between median eyes marked with black pigmentation. Chelicerae: manus shiny yellowish brown to dark brown with dark brown reticulations; fingers reddish brown to dark brown, with reddish brown teeth. Pedipalps: femur and patella dark brown dorsally, with black carinae. Chela manus lustrous reddish brown; fingers dark brown posteriorly and dark yellow anteriorly. Denticles black. Legs: tarsi dark Table 2. Comparative measurements of types of Androctonus najdensis sp. nov. Abbreviations: length (L), width (W, in carapace it corresponds to posterior width), depth (D). Dimensions (mm) Ratio Androctonus najdensis sp. nov. ♂, holotype Androctonus najdensis sp. nov. ♀, paratype Carapace L / W 12.26 / 10.56 11.79 / 11.63 Mesosoma L 25.37 22.14 Tergite VII L / W 7.77 / 10.22 6.57 / 11.40 Metasoma + telson L 55.73 56.33 Segment I L / W / D 7.70 / 7.34 / 6.15 7.98 / 7.08 / 6.14 Segment II L / W / D 8.47 / 8.34 / 7.25 9.50 / 7.62 / 6.76 Segment III L / W / D 9.62 / 9.43 / 8.17 9.26 / 8.56 / 7.50 Segment IV L / W / D 10.31 / 9.31 / 8.41 9.90 / 7.93 / 7.40 Segment V L / W / D 10.96 / 8.08 / 7.20 10.95 / 7.11 / 6.04 Telson L / W / D 8.67 / 3.88 / 3.16 8.74 / 4.24 / 3.16 Pedipalp L 36.00 37.88 Femur L / W 8.41 / 3.03 8.80 / 2.78 Patella L / W 10.07 / 4.21 10.67 / 4.08 Chela L 17.52 18.41 Manus L / W / D 7.72/ 5.38 / 4.77 8.03 / 5.44 / 4.74 Movable finger L 11.67 11.44 Fixed finger L 9.01 8.83 Total L 93.36 90.26 38 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia Figure 1. Habitus of Androctonus najdensis sp. nov., male holotype and female paratype. A, B. Male; C, D. Female; A, C. Dorsal view; B, D. Ventral view. Scale bar: 10 mm. 39 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia yellow; other segments brown. Mesosoma: blackish brown in males; dark brown to dark reddish brown in females. Sternites III–V yellowish brown; poststernites dark yellow medially. Sternite VI pale brown; sternite VII dark brown. Coxae yellowish brown to reddish brown. Pectines pale yellow. Metasoma: Figure 2. Androctonus najdensis sp. nov. male holotype and female paratype. A, C. Male; B, D. Female; A, C. Carapace and mesosoma; B, D. Sternopectinal area and ventral of mesosoma. Scale bar: 10 mm. Figure 3. Androctonus najdensis sp. nov. male holotype and female paratype, under UV light. A, C. Male; B, D. Female; A, B. Carapace and mesosoma; C, D. Sternopectinal area and ventral of mesosoma. Scale bar: 10 mm. 40 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia ventral surfaces of segments I–V dark brown to black in males and dark brown in females. Lateral and dorsal surfaces reddish brown to brown. Carinae exhibit dark brown to black pigmentation. Vesicle: black ventrally, reddish brown dorsally. Aculeus: reddish brown at base, black at tip. Morphology. Prosoma (Figs 4A, C, 5A, C): carapace trapezoidal, longer than wide. Carinae strong with coarse granules in males, and moderate granules in females. Intercarinal area densely covered with coarse to medium granules in males, and with medium to minute granules in females. Granules larger and flattened anteriorly, and smaller between posteriomedian, centromedian, and anteromedian carinae. Anterior margin nearly straight and pitted, bearing several stout macrosetae and a row of large, rounded granules. Figure 4. Androctonus najdensis sp. nov. male holotype and female paratype. A, B. Male; C, D. Female; A, C. Carapace; B, D. Sternopectinal area. Scale bar: 10 mm. 41 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia All furrows moderate in depth. Median ocular tubercle located slightly anterior to the centre of carapace. Median eyes separated by a distance equivalent to two ocular diameters, situated in an area bearing several medium-sized granules. There are five pairs of lateral eyes: the first three are moderate in size, aligned, and located above an area with moderate granulation; the last two are vestigial. Sternum typical for the genus (Type 1), triangular and narrow, longer than wide. The genital operculum longitudinally divided into two semi-oval plates. Pectines (Figs 4B, D, 5B, D): long (extending well beyond leg IV coxa/trochanter joint in males, slightly surpassing it in females), narrow, and densely setose. Tooth count ranges from 31–33 in males and 23–28 in females. Basal plate heavily sclerotized and wider than long; anterior margin bears a strong median indentation, while posterior margin broadly convex. Figure 5. Androctonus najdensis sp. nov. male holotype and female paratype, under UV light. A, B. Male; C, D. Female; A, C. Carapace; B, D. Sternopectinal area. Scale bar: 10 mm. 48 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia In A. crassicauda and A. orientalis, the fifth metasomal segment in males is elongated, and most of the dorsolateral carinae are serrate. In contrast, in A. najdensis sp. nov., the fifth metasomal segment in males is stocky, and only a small portion of the dorsolateral carina is serrate. Besides, in A. crassicauda and A. orientalis the dorsolateral carina of the fourth segment is distinctly dentate, whereas it is serrate in A. najdensis sp. nov. Figure 11. Androctonus najdensis sp. nov. metasoma and telson of male holotype and female paratype, under UV light. A, C, E. Male; B, D, F. Female; A, B. Lateral view; C, D. Dorsal view; E, F. Ventral view. Scale bar: 10 mm. 49 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia Additionally, the ventrolateral carinae of fifth metasomal segment in A. najdensis sp. nov. lack enlarged denticles, whereas in A. ammoneus, A. azerianus, A. barahoeii, A. caspius, A. ishtar, A. kunti, A. sumericus, A. transcaucasicus and A. turkiyensis ventrolateral carinae bear enlarged or somewhat large denticles. Coloration is brown in A. ammophilus and A. omanensis whereas it is black in A. najdensis sp. nov. The lateral surface of segment V of the metasoma is smooth and the ventrolateral carinae of segment V bear dentate granules posteriorly in A. omanensis whereas the lateral surface of segment V is finely granular and the ventrolateral carinae of segment V are subconical, and do not bear dentate granules in A. najdensis sp. nov. The seventh sternite is smooth in A. ammophilus whereas in A. najdensis sp. nov. it is finely granular. Key to species of the genus Androctonus in the Middle East, Turkey, and Iran 1 Coloration reddish brown, brown, or black ..................................................2 – Coloration yellow .........................................................................................17 2 Chela stocky, fingers short............................................................................3 – Chela elongated, fingers long .....................................................................19 3 Ventrolateral carinae on segment V with enlarged denticles .....................4 – Ventrolateral carinae on segment V without large denticles ....................12 4 Intercarinal area of carapace covered with small or medium sized granules. Chela has a distinct gap between fingers .......................A. sumericus – Intercarinal area of carapace covered with coarse granules. Chela exhibits an indistinct gap between fingers. ...............................................................5 5 Metasoma II with lateral inframedian carinae incomplete but developed on the posterior ¾ ......................................................................A. azerianus – Metasoma II with lateral inframedian carinae absent, represented by only 2–5 denticles on the posterior part ..............................................................6 6 Pedipalp chela internal surface densely or moderately granular with fine granules. Chela manus wide in males and narrow in females ...................7 – Pedipalp chela internal surface smooth, with only several fine granules. There is no noticeable difference in chela shapes between the sexes .....8 7 Pedipalp chela internal surface densely granular. Ventrolateral carinae on segment V with 1 or 2 separated, enlarged denticles ...............A. barahoeii – Pedipalp chela internal surface moderately granular. Ventrolateral carinae on segment V with 2 fixed, enlarged denticles ................................A. ishtar 8 Metasoma lateral surfaces rough ................................................................9 – Metasoma lateral surfaces smooth ...........................................................10 9 Ventrolateral carinae of segment V bear conspicuous 2 or 3 subconical denticles ....................................................................................A. turkiyensis – Ventrolateral carinae of segment V bear 2 or 3 less conspicuous subspinoid denticles ...........................................................................A. ammoneus 10 Chela finely granulated, tibial spurs on legs III and IV moderate ....A. kunti – Chela smooth, tibial spurs on legs III and IV strong ..................................11 50 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia 11 Pedipalp chela length/width ratio 3.7 (male) to 4.6 (female) ....................... ..........................................................................................A. transcaucasicus – Pedipalp chela length/width ratio 4.4–4.7 in both sexes, without sexual dimorphism .................................................................................... A. caspius 12 Coloration reddish brown or yellowish brown ..........................A. tihamicus – Coloration brown or black ...........................................................................13 13 Metasomal segment V of metasoma stocky especially in males. Only a small portion of dorsolateral carina of segment V serrate. Dorsolateral carina of segment IV serrate ......................................................................14 – Metasomal segment V of metasoma especially in males elongate. Most of dorsolateral carina of segment V serrate. Dorsolateral carina of segment IV distinctly dentate ...........................................................................16 14 Lateral surface of metasomal segment V smooth. Ventrolateral carinae of segment V bear dentate granules at posterior portion ................................. ...................................................................................................A. omanensis – Lateral surface of metasomal segment V finely granular. Ventrolateral carinae of segment V bear subconical, do not bear dentate granules ............ ......................................................................................................................15 15 Coloration is black. Sternite VII finely granular ........... A. najdensis sp. nov. – Coloration is brown. Sternite VII smooth ..............................A. ammophilus 16 Sternites finely granular ......................................................... A. crassicauda – Sternites smooth .........................................................................A. orientalis 17 Metasomal segments IV and -V and telson yellow ...................................18 – Metasomal segments IV and V and telson black ....................... A. sistanus 18 Metasomal segments stocky ......................................................A. australis – Metasomal segments elongated ...............................................A. amoreuxi 19 Chela length/width ratio 7.27 in male and 8.24 in female .........A. minaeus – Chela length/width ratio 5.65 in male and 6.45 in female ............................ ..........................................................................................................A. bicolor Figure 12. Androctonus najdensis sp. nov., metasoma V and telson of male holotype and female paratype. A, B. Male; C, D. Female; A, C. Lateral view; C, D. Ventral view. 51 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia Ecology Most specimens were collected from the Najd Plateau region of central Saudi Arabia and from wadis surrounding the Tuwayq Escarpment, with additional samples obtained from the Eastern Province and Ha’il. Najd is a Figure 13. Androctonus najdensis sp. nov., metasoma V and telson of male holotype and female paratype, under UV light. A, B. Male; C, D. Female; A, C. Lateral view; B, D. Ventral view. Figure 14. Androctonus najdensis sp. nov., male holotype, right legs I–IV. 52 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia plateau that ranges in elevation from 762 to 1,525 meters and slopes eastward. Notable topographic features include the Aja and Salma mountains, Jabal Shammar, and the Tuwayq mountain range. Dry wadis, such as Wadi Hanifa and Wadi Na’am, play an important role in retaining rainwater. The recorded elevation range for the species is 20–800 meters, with the lowest occurrences near the eastern coast and the highest on the Najd Plateau. The new species is likely lapidicolous, inhabiting areas under rocks and debris in wadis within both sedimentary and igneous hills and mountains, as well as animal burrows in sandy desert soils. Genetic analysis The phylogenetic tree topologies recovered by the analysis of the COI data set resulted in an identical topology between the Maximum-parsimony and the neighbour-joining trees (Fig. 16). However, the general topology of the Figure 15. Androctonus najdensis sp. nov., female paratype, right legs I–IV. 53 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia Figure 16. Neighbour-joining (NJ) phylogenetic tree of Androctonus species based on COI sequences from Saudi Arabia and the Middle East. Numbers above and below branches indicate Bayesian posterior probabilities/ NJ distance values/ maximum parsimony bootstrap values. 54 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia maximum-parsimony tree was slightly different from those obtained by Bayesian inference analyses. Androctonus najdensis sp. nov. forms a monophyletic clade distinct from A. crassicauda s.l. (from Saudi Arabia, Iraq, and Iran) and other related Androctonus species analysed (Fig. 16). Also, the new species differs from A. crassicauda by a raw genetic distance of 7.0–8.0%, and from other Androctonus species by 10–11.0% (Table 3). Figure 17. A map showing the distribution of A. ammoneus, A. ammophilus, A. barahoeii, A. crassicauda, A. ishtar, A. najdensis sp. nov., A. omanensis, A. sumericus and A. tihamicus in Iraq, Iran, Jordan, Oman, Saudi Arabia, and United Arab Emirates. Table 3. The uncorrected p-distance of the sequence divergence of COI mtDNA sequences between Androctonus samples included in this study. 1 2 3 4 5 6 7 8 9 10 11 12 1. A. najdensis sp. nov. KSA 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 2. A. crassicauda _Northern_Border_KSA 0.07 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 3. A. crassicauda _Al_Jowf_KSA 0.07 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 4. A. crassicauda _Iran 0.08 0.05 0.05 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 5. A. crassicauda _Iraq 0.08 0.05 0.05 0.03 0.01 0.01 0.01 0.01 0.01 0.01 0.02 6. A. liouvillei 0.11 0.10 0.10 0.09 0.09 0.01 0.01 0.01 0.01 0.01 0.02 7. A. gonneti 0.11 0.10 0.10 0.09 0.09 0.08 0.01 0.01 0.01 0.01 0.02 8. A. australis 0.10 0.10 0.10 0.10 0.09 0.11 0.10 0.01 0.01 0.01 0.02 9. A. mauritanicus 0.10 0.10 0.10 0.10 0.10 0.09 0.11 0.08 0.01 0.01 0.02 10. A. amoreuxi 0.11 0.10 0.10 0.11 0.10 0.07 0.09 0.10 0.10 0.01 0.02 11. A. bicolor 0.11 0.11 0.11 0.11 0.11 0.08 0.10 0.10 0.09 0.10 0.02 12. Outgroup 0.63 0.64 0.64 0.65 0.64 0.64 0.64 0.64 0.66 0.64 0.65 55 ZooKeys 1262: 33–59 (2025), DOI: 10.3897/zookeys.1262.163047 Ersen Aydın Yağmur et al.: Androctonus najdensis from Saudi Arabia Discussion Several authors have employed mitochondrial genes to identify cryptic species within the genus Androctonus, including Ben Ali et al. (2000), Othmen et al. (2009), Ozkan et al. (2010), Desouky and Alshammari (2010), Coelho et al. (2014), and Alqahtani et al. (2022a, b, 2023). In the present study, we conducted a molecular phylogenetic analysis using the COI mitochondrial gene for this purpose. The results revealed a genetic divergence (p-distance = 0.07–0.08) between A. najdensis sp. nov. and populations of A. crassicauda from northern Saudi Arabia, Iraq, and Iran. Additionally, the new species differed from North African Androctonus species by a p-distance of 0.10–0.11 (Table 3). The combined molecular and morphological evidence strongly supports the recognition of the Najd Plateau population as a distinct species. Several previous studies (Vachon 1979; Hendrixson 2006; Al-Asmari et al. 2009, 2013; Alqahtani et al. 2019) have reported A. crassicauda from various localities and provided general illustrations. Vachon (1979), Al-Asmari et al. (2009), and Alqahtani et al. (2019) illustrated specimens from Riyadh, Ha’il, and southwestern Saudi Arabia, respectively. However, Hendrixson (2006) did not specify the locality of the illustrated specimen. These specimens show morphological similarities to A. najdensis sp. nov., particularly in their dark coloration and the absence of enlarged denticles on the fifth metasomal segment. Notably, specimens of the newly described species were collected from Riyadh and Ha’il, suggesting that the individuals illustrated in previous studies may in fact belong to A. najdensis sp. nov. Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Use of AI No use of AI was reported. Funding The authors are thankful to the Deanship of Graduate Studies and Scientific Research at University of Bisha for supporting this work through the Fast-Track Research Support Program. Author contributions All authors have contributed equally. Author ORCIDs Ersen Aydın Yağmur https://orcid.org/0000-0002-0396-3975 Abdulaziz R. 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