Xenobuthus, Lowe, 2018

Lowe, Graeme, 2018, The genera Butheolus Simon, 1882 and Xenobuthus gen. nov. (Scorpiones: Buthidae) in Oman, Euscorpius 261, pp. 1-73 : 63-66

Key to species of Butheolus and Xenobuthus gen. n. examined in this study (based on adults)

1 Small to medium sized scorpions, 35–50 mm long; metasomal segments sparsely granular on lateral and ventral sides; basal lobe of hemispermatophore a broad, shallow, curved scoop; pedipalp fingers with 8–10 subrows of denticles; males with macrosetae similar in length to those of females; soles of telotarsi I–III often with single row of setae ..….... Xenobuthus gen. n..... 5

– Small scorpions, <36 mm long; metasomal segments densely granular on lateral and ventral sides; basal lobe of hemispermatophore a small, narrow, hook-like process; pedipalp fingers typically with 6–7 subrows of denticles; males with shorter macrosetae than females; soles of telotarsi I–III bearing two rows of setae .........…….......................... Butheolus Simon , 188 2 ..... 2

2 Pedipalp patella L/W <2.3, chela manus strongly carinate; telson with large subaculear tubercle, posterior vesicle slope forming acute angle with aculeus base ...………………...... Butheolus thalassinus Simon, 1882

– Pedipalp patella L/W> 2.3, chela manus smooth or with very weak carinae; telson with subaculear tubercle small or indistinct, posterior vesicle slope forming obtuse angle with aculeus base ...……………………...... 3

3 Metasoma and telson densely pilose, with abundant macrosetae; basitarsus III with 11–12 retrosuperior setae (bristle-comb) .................... B. villosus Hendrixson, 2006

– Metasoma and telson with sparse setation; basitarsus III with 4–10 retrosuperior setae (bristle-comb) …. 4

4 Carapace and tergites coarsely granulated; color of metasoma I–II yellow to light brown; pedipalp patella with complete dorsomedian carina .... B. harrisoni sp. n.

– Carapace and tergites finely granulated; color of metasoma I–II dark brown; pedipalp patella with dorsomedian carina restricted to distal half of segment ...........…………….............. B. gallagheri Vachon, 1980

5 Carapace, mesosoma and metasoma I–III dark brown to black; metasoma IV with 10 carinae, lateral median carinae distinct; ventromedian carina of metasoma V bifurcate; metasoma V in males with ventral intercarinal surface granulated posteriorly ...........…........ ………..……… Xenobuthus anthracinus (Pocock, 1 985)

– Carapace, mesosoma and metasoma I–III bright yellow; metasoma IV with 8 carinae, lateral median carinae obsolete; ventromedian carina of metasoma V not bifurcate; metasoma V in males with ventral intercarinal surface smooth posteriorly .... Xenobuthus xanthus sp. n.

The above key omits two species, Butheolus arabicus Lourenço & Qi, 2006 , and B. hallani Lourenço & Rossi, 2017 (= B. pallidus Lourenço & Duhem, 2012 ), because the author was not able to loan and examine the types of these two species.

From the published description, and the habitus shown in images on the MNHN website, B. arabicus does not fit the diagnosis of Butheolus given here. Instead, it complies with certain characters of Xenobuthus gen. n.: i.e., 1) large size and general proportion and shape of body and appendages resemble X. anthracinus and X. xanthus ; 2) 8–9 denticle subrows on pedipalp chela fingers. It is hereby provisionally transferred to that genus: Butheolus arabicus Lourenço & Qi, 2006 = Xenobuthus arabicus ( Lourenço & Qi, 2006) comb. n..

The type locality “East of Khamis Mushayt” suggests the possibility that X. arabicus is a junior synonym of X. anthracinus , since the latter is also known from Khamis Mushayt (by the AMNH female, examined here and by Hendrixson, 20 06). Lourenço & Qi (2006) distinguished X. arabicus from X. anthracinus as follows:

1) “much larger overall size”, i.e. paratype female 40.4 mm vs. 25.3 mm length of a female X. anthracinus (cf. their Tab. 1 , cited as a ‘paratype’): this character is not applicable because: (i) adult female X. anthracinus can be up to 40–5 0 mm long ( Figs. 1 98–199 , Tab. 7 ), and the AMNH female is ca. 35 mm long ( Hendrixson, 2006). The female studied by Lourenço & Qi (2006) is the same size as the lectotype female (♀ 25 mm, photograph examined) of X. anthracinus in ZMUH designated by Kovařík (2004), and is thus likely to be immature or juvenile. It is not a paratype, but either a paralectotype, or possibly the lectotype itself. (ii) the holotype male of X. arabicus (total L 35.6 mm, carapace L 4.7 mm) is about the same size as the holotype male of X. anthracinus (total L 36.5 mm, carapace L 4.4 mm, cf. Pocock, 1895: 295).

2) “strongly marked” (= strongly developed) carinae on tergite VII and metasoma, and granulation of carapace tergites and coxapophysis: this character may not be applicable because adult X. anthracinus also have strong carination on tergite VII and metasoma, and strong granulation on carapace, tergites and coxal endites I–II (= coxapophyses) ( Figs. 194–201 , 252–257 ). The carination and granulation may not be fully developed in the probably immature or juvenile female used for comparison by Lourenço & Qi (2006).

3) “metasomal segments I to III with 10 carinae in both sexes”: this character is not applicable because adult X. anthracinus can also have 10 carinae on metasoma I–III in both sexes ( Figs. 252–257 ). Either this character is variable, or the carination is not fully developed in the probably immature or juvenile female used for comparison by Lourenço & Qi (2006).

Another potential difference is in coloration, as the base color of X. arabicus was described as “yellow to reddish-yellow”, consistent with color photographs of the holotype posted on the MNHN website, which contrasts with the dark reddish-brown to black color of X. anthracinus . However, biological pigments can suffer fading or wash out after long storage in alcohol, and coloration is not a very reliable character in old specimens that were not fixed by specific methods that preserve coloration, e.g. heat shock and aldehyde fixation ( Williams, 1968). The problem was well demonstrated by the holotype of Butheolus gallagheri (also in MNHN), that was loaned and examined by the author in 1994, only 14 years after its description by Vachon (1980) as “brun chocolat” (= dark brown natural color, exhibited by live animals and by the aldehyde-fixed materials studied here). By 1994, the holotype had already faded to a pale yellow color on the carapace and tergites, and a pale orange brown color on the metasoma, and the base of the pedipalp fingers had lost the diagnostic melanic pigmentation that was noted by Vachon (1980). The holotype of X. arabicus was presumably stored much longer in alcohol (34 years) before it was described.

Although X. arabicus and X. anthracinus seem similar and were both collected in the vicinity of Khamis Mushayt, they could nevertheless be distinct species. In Dhofar, Oman, similar but distinct species of Butheolus and Xenobuthus exist in relatively close proximity. Lourenço & Qi (2006) noted that X. arabicus only bears 8 carinae on metasoma IV, which is a diagnostic character separating X. xanthus from X. anthracinus . The question might be addressed by restudying the types of X. arabicus , or by further sampling the Xenobuthus populations in the region of Khamis Mushayt.

The taxonomic status of B. hallani , based on a single holotype male from the United Arab Emirates or adjacent Oman, is also uncertain. It is not clear from the published description, and the general habitus shown in images posted on the MNHN website (reproduced in Lourenço & Rossi, 2017), whether it fits the diagnosis of Butheolus given here. In their description, Lourenço & Duhem (2012) noted:

1) “posterior margin of sternites III to VI without denticulations”: however, such denticulations are proposed to be diagnostic for both Butheolus and Xenobuthus ( Figs. 332–335 ), and were present and in all species examined here. Although the sternite denticulations are weaker and may be overlooked in females, they are conspicuous in males, and the holotype of B. hallani is male.

2) metasoma V with “lateroventral carinae with a few slightly spinoid granules in the distal region”: their Fig. 4 depicts an irregularly dentate posterior carina with two enlarged denticles that are considerably larger than the anterior dentition, a pattern that differs from that seen in Butheolus and Xenobuthus , which have numerous regular denticles gradually increasing in size posteriorly.

These characters, together with the small body size (18 mm), and presence of only 5–6 subrows of denticles on the pedipalp fingers, are more suggestive of Neobuthus , than Butheolus ( Kovařík & Lowe, 2012; Lourenço, 2001, 2005; Lourenço & Qi, 2006; Lowe & Kovařík, 2 016). Other key taxonomic characters that could be relevant to its generic affiliation (e.g. position of trichobothrium V 2 on pedipalp manus, number of denticles on ventral aspect of cheliceral fixed finger) have yet to be specified. In any case, the presence of either Butheolus or Neobuthus in the southeastern corner of the Arabian Peninsula would be a significant range extension for either genus.

Figures

Figures 1–2: Habitus of male Butheolus gallagheri Vachon, 1980. Fig. 1. Dorsal aspect. Fig. 2. Ventral aspect. Oman, wadi above Khor Rori Beach, E. of Taqah, 17°3.2'N 54°25.33'E, 18.X.1993, leg. G. Lowe. Scale bar: 5 mm.

Figures 3–4: Prosoma and mesosoma of male Butheolus gallagheri Vachon, 1980. Fig. 3. Dorsal aspect, carapace and tergites. Same locality data as male in Figs. 1–2. Fig. 4. Ventral aspect, coxosternal area and sternites. Oman, Salalah, leg. A. Ullrich. Scale bar: 1 mm.

Figures 5–6: Habitus of female Butheolus gallagheri Vachon, 1980. Fig. 5. Dorsal aspect. Fig. 6. Ventral aspect. Same locality data as male in Figs. 1–2. Scale bar: 5 mm.

Figures 7–8: Prosoma and mesosoma of adult female Butheolus gallagheri Vachon, 1980. Fig. 7. Dorsal aspect, carapace and tergites. Fig. 8. Ventral aspect, coxosternal area and sternites. Same locality data as male in Figs. 1–2. Scale bar: 1 mm.

Figures 9–32: Pedipalp of Butheolus gallagheri Vachon, 1980. Figs. 9–20. Male (♂). Dorsal (9–11), external (12–14), ventral (15–17) and internal (18–20) aspect of femur (9, 12, 15, 18), patella (10, 13, 16, 19) and chela (11, 14, 17, 20). Figs. 21–32. Female (♀). Dorsal (21–23), external (24–26), ventral (27–29) and internal (30–32) aspect of femur (21, 24, 27, 30), patella (22, 25, 28, 31) and chela (23, 26, 29, 32). Both sexes with same locality data as male in Figs. 1–2. Scale bars: 1 mm.

Figures 33–50: Trichobothrial maps and chela finger dentition of Butheolus gallagheri Vachon, 1980. Male (♂): dorsal (33), external (34) and ventral (35) aspect of chela; dorsal (39) and external (40) aspect of patella; dorsal (45), external (46) and internal (47) aspect of femur; dentition of movable finger (MF) (41) and fixed finger (FF) (42). Female (♀): dorsal (36), external (37) and ventral (38) aspect of chela; dorsal (43) and external (44) aspect of patella; internal (48), dorsal (49) and external (50) aspect of femur. Same locality data as male in Figs. 1–2. Scale bars: 1 mm (♂, ♂ dentition, ♀).

Figures 51–54: Leg tarsi, tibiae and patellae of male Butheolus gallagheri Vachon, 1980. Retrolateral aspect, left leg I tibia, basitarsus and telotarsus (51), left legs II–IV, patella, tibia, basitarsus and telotarsus (52–54 respectively). Same locality data as male in Figs. 1–2. White light illumination. Scale bar: 1 mm.

Figures 55–58: Hemispermatophore of Butheolus gallagheri Vachon, 1980. Fig. 55. Whole right hemispermatophore, convex aspect. Scale bar: 1 mm. Figs. 56–58. Capsule region and flagellum of right hemispermatophore, anterior (56), convex (57) and posterior (58) aspects. In convex view (57), the capsule is compressed to show outlines of lobes. Same locality data as male in Figs. 1–2. White light illumination. Scale bar: 200 µm.

Figures 59–64: Metasoma and telson of Butheolus gallagheri Vachon, 1980. Figs. 59–61. Male (♂). Dorsal (59), right lateral (60) and ventral (61) aspects. Figs. 62–64. Female (♀). Dorsal (62), right lateral (63) and ventral (64) aspects. Same locality data as male in Figs. 1–2. Scale bars: 2 mm.

Figures 65–68: Chelicerae of male Butheolus gallagheri Vachon, 1980 and B. harrisoni sp. n. Figs. 65–66. B. gallagheri, right chelicera, dorsal (65) and ventral (66) aspect. Same locality data as male in Figs. 1–2. Figs. 67–68. B. harrisoni sp. n., right chelicera, dorsal (67) and ventral (68) aspect. Paratype male, Oman, Jabal Qara, north slopes, Nejd desert, 17°17.83'N 54°5.11'E, 16.X.1993, leg. G. Lowe. Scale bar: 500 µm.

Figures 69–70: Habitus of male Butheolus harrisoni sp. n. Fig. 69. Dorsal aspect. Fig. 70. Ventral aspect. Holotype male (♂), Oman, Jabal Qara, Salalah-Thumrait road, 17°17.26'N 54°5.36'E, 17.X.1993, leg. G. Lowe. Scale bar: 5 mm.

Figures 71–72: Prosoma and mesosoma of male Butheolus harrisoni sp. n. Fig. 71. Dorsal aspect, carapace and tergites. Fig. 72. Ventral aspect, coxosternal area and sternites. Holotype male. Scale bar: 1 mm.

Figures 73–74: Habitus of female Butheolus harrisoni sp. n. Fig. 73. Dorsal aspect. Fig. 74. Ventral aspect. Paratype female, same locality data as male in Figs. 67–68. Scale bar: 5 mm.

Figures 75–76: Prosoma and mesosoma of adult female Butheolus harrisoni sp. n. Fig. 75. Dorsal aspect, carapace and tergites. Fig. 76. Ventral aspect, coxosternal area and sternites. Paratype female, same locality data as male in Figs. 67–68. Scale bar: 1 mm.

Figures 77–100: Pedipalp of Butheolus harrisoni sp. n. Figs. 77–88. Holotype male (♂). Dorsal (77–79), external (80–82), ventral (83–85) and internal (86–88) aspect of femur (77, 80, 83, 86), patella (78, 81, 84, 87) and chela (79, 82, 85, 88). Figs. 89– 100. Paratype female (♀), same locality data as male in Figs. 67–68. Dorsal (89–91), external (92–94), ventral (95–97) and internal (98–100) aspect of femur (89, 92, 95, 98), patella (90, 93, 96, 99) and chela (91, 94, 97, 100). Scale bars: 1 mm.

Figures 101–118: Trichobothrial maps and chela finger dentition of Butheolus harrisoni sp. n. Holotype male (♂): dorsal (101), external (102) and ventral (103) aspect of chela; dorsal (107) and external (108) aspect of patella; dorsal (113), external (114) and internal (115) aspect of femur; dentition of movable finger (MF) (109) and fixed finger (FF) (110). Paratype female (♀), same locality data as male in Figs. 67–68: dorsal (104), external (105) and ventral (106) aspect of chela; dorsal (111) and external (112) aspect of patella; internal (116), dorsal (117) and external (118) aspect of femur. Scale bars: 1 mm (♂, ♂ dentition, ♀).

Figures 119–122: Leg tarsi and tibiae of male Butheolus harrisoni sp. n. Holotype male. Retrolateral aspect, left leg I (119), II (120), III (121), IV (122) tibia, basitarsus and telotarsus. White light illumination. Scale bar: 1 mm.

Figures 123–126: Hemispermatophore of Butheolus harrisoni sp. n. Fig. 123. Whole right hemispermatophore, convex aspect. Scale bar: 1 mm. Figs. 124–126. Capsule region of right hemispermatophore, anterior (124), convex (125) and posterior (126) aspects. In convex view (125), the capsule is compressed to show outlines of lobes. Paratype male, same locality data as male in Figs. 67–68. White light illumination. Scale bar: 200 µm.

Figures 127–132: Metasoma and telson of Butheolus harrisoni sp. n. Figs. 127–129. Holotype male (♂). Dorsal (127), right lateral (128) and ventral (129) aspects. Figs. 130–132. Paratype female (♀), same locality data as male in Figs. 67–68. Dorsal (130), right lateral (131) and ventral (132) aspects. Scale bars: 2 mm.

Figures 133–147: Scatter plots showing variation in morphometric ratios of Butheolus gallagheri Vachon, 1980 and B. harrisoni sp. n. Selected measurements normalized to carapace length (CL). Each symbol represents one specimen. B. gallagheri: black symbols; B. harrisoni: orange symbols. Males: filled circles, females: open circles. Abbreviations: L, length; W, width, WA anterior width, WP posterior width, D depth.

Figures 148–150: Histograms showing variation in meristic counts of basitarsal setation and pectine teeth for Butheolus gallagheri Vachon, 1980 and B. harrisoni sp. n. Figs. 148–149. Distributions of number of retrosuperior macrosetae (“bristlecomb” setae) on basitarsi I–III for males (148) and females (149). Fig. 150. Distributions of number of pectine teeth in male (♂) and female (♀) combs. In all plots: B. gallagheri, black bars; B. harrisoni, orange bars. Ordinates are numbers of tarsi or combs, pooling data from left and right appendages of all specimens examined.

Figures 151–162: Scatter plots showing variation in morphometric ratios of species of Butheolus and Xenobuthus gen. n. Figs. 151–156. Selected ratios of males (♂). B. gallagheri: black filled symbols; B. harrisoni: orange filled symbols; B. thalassinus: cyan circles; X. anthracinus: magenta circles; X. xanthus: yellow circles. Figs. 157–162. Selected ratios of females (♀). B. gallagheri: black open symbols; B. harrisoni: orange open symbols; B. villosus: light green circles; X. anthracinus: magenta circles; X. xanthus: yellow circles. Abbreviations: L, length; W, width (carapace W = posterior width), D depth.

Figures 163–164: Habitus of male Butheolus thalassinus Simon, 1882. Fig. 163. Dorsal aspect. Fig. 164. Ventral aspect. Yemen, Ta'izz, 1158 m a.s.l., under rock on Euphorbia-Aloe hill, 10. I. 1951, H. Hoogstraal (cf. Sissom, 1994: 7–8, figs. 8–13). Scale bar: 5 mm.

Figures 165–166: Prosoma and mesosoma of male Butheolus thalassinus Simon, 1882. Fig. 165. Dorsal aspect, carapace and tergites. Fig. 166. Ventral aspect, coxosternal area and sternites. Same male as in Figs. 163–164. Scale bar: 1 mm.

Figures 167–178: Metasoma, telson, pedipalp and trichobothrial map of Butheolus thalassinus Simon, 1882. Male, same as in Figs. 163–164. UV fluorescence. Figs. 167–169. Metasoma and telson. Dorsal (167), right lateral (168) and ventral (169) aspects. Scale bar: 2 mm. Figs. 170–176. Pedipalp and trichobothria. Dorsal (170), external (171) and ventral (172) aspect of chela; dorsal (173) and external (174) aspect of patella; dorsal (175) and internal (176) aspect of femur. Scale bar: 1 mm. Figs. 177–178. Dentition of fixed finger (FF) (177) and movable finger (MF) (178). Scale bar: 500 µm.

Figures 179–180: Habitus of Butheolus villosus Hendrixson, 2006. Holotype female (♀). Fig. 179. Dorsal aspect. Fig. 180. Ventral aspect. Khashm Dhibi, Saudi Arabia, 28.II.1980, leg. A. Barkham, NHMB 0618 (cf. Hendrixson, 2006: 59–61, pl. 7, fig. 9). Scale bar: 5 mm.

Figures 181–182: Prosoma and anterior mesosoma of female Butheolus villosus Hendrixson, 2006. Holotype female. Fig. 181. Dorsal aspect, carapace and tergites I–III. Fig. 182. Ventral aspect, coxosternal area and sternites III–V. UV fluorescence. Scale bars: 1 mm.

Figures 194–195: Habitus of male Xenobuthus gen. n. anthracinus (Pocock, 1895). Fig. 194. Dorsal aspect. Fig. 195. Ventral aspect. Same locality data as male in Table 7. Scale bar: 5 mm.

Figures 196–197: Prosoma and mesosoma of male Xenobuthus gen. n. anthracinus (Pocock, 1895). Fig. 196. Dorsal aspect, carapace and tergites. Fig. 197. Ventral aspect, coxosternal area and sternites. Same locality data as male in Table 7. Scale bar: 2 mm.

Figures 198–199: Habitus of female Xenobuthus gen. n. anthracinus (Pocock, 1895). Fig. 198. Dorsal aspect. Fig. 199. Ventral aspect. Same locality data as female in Table 7. Scale bar: 5 mm.

Figures 200–201: Prosoma and mesosoma of female Xenobuthus gen. n. anthracinus (Pocock, 1895). Fig. 200. Dorsal aspect, carapace and tergites. Fig. 201. Ventral aspect, coxosternal area and sternites. Same locality data as female in Table 7. Scale bar: 2 mm.

Figures 252–257: Metasoma and telson of Xenobuthus gen. n. anthracinus (Pocock, 1895). Figs. 252–254. Male (♂). Dorsal (252), right lateral (253) and ventral (254) aspects. Figs. 255–257. Female (♀). Dorsal (255), right lateral (256) and ventral (257) aspects. Both sexes with same locality data as in Table 7. Scale bars: 2 mm.

Figures 330–337: Diagnostic characters of genera Butheolus and Xenobuthus gen. n.. Figs. 330–331. Hemispermatophore basal lobes of B. gallagheri (330) and X. anthracinus (331); axial views of right (330) and mirrored left (331) hemispermatophore. Oriented with convex side up, anterior margin left and posterior margin right. Abbreviations: b, basal lobe; m, median lobe. Scale bars: 50 µm. Figs. 332–337. Dentition of posterior margin of sternite IV in male B. gallagheri (332), B. harrisoni sp. n. (333), X. anthracinus (334), X. xanthus sp. n. (335), Hottentotta jayakari (Pocock, 1895) (336) and H. pellucidus Lowe, 2010 (337). UV fluorescence. Scale bars: 100 µm. Locality data: 330 and 332, as in Tab. 1; 331 and 334, as in Tab. 7; 333, paratype male, same locality as holotype; 335, holotype; 336, Oman, Rte 13, ca. 5.9 km E junction Wadi Mistal Rd, 23°21.33'N 57°38.21'E, 460 m a.s.l., 26.IX.1994, leg. G, Lowe, M.D. Gallagher; 337, Oman, Jabal Bani Jabir, IX.1995, 1800 m a.s.l., leg A. Francois, C. DeLise (ONHM).