Xenobuthus anthracinus ( Pocock, 1895 ) Lowe, 2018

Lowe, Graeme, 2018, The genera Butheolus Simon, 1882 and Xenobuthus gen. nov. (Scorpiones: Buthidae) in Oman, Euscorpius 261, pp. 1-73 : 39-51

Xenobuthus anthracinus ( Pocock, 1895) , comb. n.

( Figs. 151–162 , 194–259 , 326–327 , 331, 334 , 338 , Tab. 7 )

Buthus anthracinus Pocock, 1895: 294–295 , 315, pl. IX, figs. 1, 1a.

Buthus anthracinus: Kraepelin, 1899: 18 ; Simon, 1910: 77; Táborský, 1934: 40; Birula, 1937: 101; Weidner, 1959: 99; Pérez, 1974: 43; Lamoral & Reynders, 1975: 504; Sissom, 1994: 36.

Buthus (Hottentotta?) antracinus : Birula, 1910: 171; Birula, 1937: 101.

Buthus (Hottentotta?) anthracinus: Birula, 1917a: 230 .

Butheolus anthracinus: Fet & Lowe, 2000: 88 ; Kovařík, 2003: 137; Kovařík, 2004: 3 , 25; Fet, Soleglad & Lowe, 2005: 2; Hendrixson, 2006: 51–53, 56–59. figs. 6, 8, pl. 6, Tab. 1 ; Lourenço & Qi, 2006: 93– 94, tab. 1; El-Hennawy, 2009: 121; Kovařík & Lowe, 2012: 2, 20, 22–23, fig. 94; Lowe et al., 2014: 117.

TYPE MATERIAL. Lectotype ♀, Yemen, Hadramaut ( ZMUH) (not examined). The syntypes of Pocock in BMNH were not found, and a lectotype was designated by Kovařík (2004: 3).

MATERIAL EXAMINED. Oman: 1♀, S of Thumrait , Nejd Desert, UV detection, edge of small vegetated wadi, open plain, fine silty soil, rock outcrops , 17°30.76' N 54°02.76'E, 580 m a.s.l., 16.X.1993, 19:28 h, leg. G. Lowe, ( NHMB); 1♂, S of Thumrait ; Nejd Desert , UV detection, silty plain, edge of small vegetated wadi, fine silty soil, open plain, rock outcrops , 17°30.77'N 54°02. 82'E, 600 m a.s.l., 19.X.1993, 23:02 h, leg. G. Lowe, ( NHMB). Saudi Arabia: 1♀ (adult or subadult?), Khamis Mushayt , 18°18'N 42°44'E, ca. 2,000 m a.s.l., leg. Digby Lickfold ( AMNH) .

DIAGNOSIS. A member of the genus Xenobuthus differentiated as follows: small to medium-sized scorpions, adults 35–50 mm; base color a uniform dark, reddish brown, almost black, all metasomal segments dark brown to black; pedipalp femur and patella light to dark brown, chela with yellow fingers, fuscosity on manus at base of fingers; legs darker brown on femur and patella, lighter on tibia, pale straw color on tarsi; carapace and tergites with moderately dense, fine granulation; metasoma IV with lateral median carinae distinct; metasoma V with ventromedian carina posteriorly bifurcate, males with ventral intercarinal surface granular on posterior 1/4 of segment; posterior metasomal segments relatively stout in male: metasoma III L/W ♂ 1.09; metasoma IV L/W ♂ 1.38; metasoma V L/W ♂ 1.66, L/D 2.17; pectine teeth 17–22.

REDESCRIPTION.

Based on 1 ♂, 1 ♀ from Dhofar, Oman.

Coloration ( Figs. 194–225 , 244–247 , 252–259 ). Base color dark brown, nearly black, on dorsal aspect of prosoma. mesosoma and all aspects of metasoma and telson; tergites with lighter lateral patches in transverse reticulated bands; telson vesicle with lighter spots at bases of macrosetae, lighter lateral stripes, and a pair of lighter sub-median stripes on ventral surface; dorsal aspect of chelicerae dark on proximal fingers and distal margin of manus, yellow-dark brown reticulated on distal half of manus; legs dark brown on trochanter, femur and patella except for lighter spots on distal patella and lighter patella I; leg tibia I pale whitish-yellow, tibia II– IV light brown; leg tarsi pale whitish-yellow; pedipalps light to dark brown on trochanter, femur and patella, chela manus light brown or yellow, with dark distal band at base of fingers, chela fingers yellow; ventral aspect of mesosoma a lighter shade of brown, except for dark brown sternite VII.

Carapace ( Figs. 194 , 196 , 198 , 200 , 326–327 ). Strongly trapezoidal, W/L 1.09–1.20, posterior W/ anterior W 2.14 –2.24; lateral flanks steeply sloped; median ocular tubercle prominent; postocular area forming triangular posteromedial plateau with shallow depressions; interocular triangle gently sloped downwards towards anterior margin, less so in female; anterior margin with 10 (♂), or 12 (♀) macrosetae, carapace otherwise devoid of macrosetae; anterolateral margins with 6 pairs of lateral eyes: 3 major ocelli and 1 minor ocellus below granular ridge, and 2 minor ocelli above granular ridge; whitish eyespot present below lateral eye cluster; all carinae of carapace obsolete except for superciliary carinae which may extend slightly anterior to median ocular tubercle; central median and posterior median carinae indicated by granule rows along edges of postocular plateau; surface with sparse to moderate irregular coarse granulation, with locally smooth areas in postocular plateau, posterior transverse and posterior marginal furrows, and most of interocular triangle; superciliary carinae smooth, with a few coarse granules on posterior slopes; granulation of female carapace similar to male, slightly weaker.

Chelicerae ( Figs. 258–259 ). Dorsal surface of manus smooth, with two short, pale microsetae on apical margin, each with adjacent granules; dorsointernal carina strong, granulate, bearing one long, dark macroseta and one short, pale microseta; fingers robust, movable finger dorsal margin with two large subdistal denticles and two small basal denticles, ventral margin with larger subdistal and smaller basal denticles, fixed finger with large subdistal denticle and proximal bicusp, two denticles on ventral surface; dorsal surface of movable finger smooth, with three pale microsetae.

Coxosternal area ( Figs. 195 , 197 , 199 , 201 ). Male. Coxa I finely granulated, endite smooth on anterior margin, sparsely granulated on posterior areas; coxa II with fine granules concentrated along margins, central surfaces sparsely granulated mostly smooth, endite smooth on anterior quarter and medial margin, granulated elsewhere; coxa III with strong peg-like granulation concentrated along anterior and distal margins, posterior margin weakly granular in proximal half, central area of sclerite smooth; coxa IV with dense band of strong peg-like granulation along anterior margin, rimmed with row of similar granules along proximal half of posterior margin, central surface smooth or very weakly shagreened; coxae I–III with scattered, mostly anterior macrosetae: coxa I 5–6, II 6–9, III 5; coxa IV with single macroseta on anterior proximal limit; sternum weakly granulated, subtriangular, with deep posteromedian pit, bearing 2 short macrosetae; genital opercula with fine granulation on anterior margin, otherwise smooth, with 4–5 macrosetae, posterolateral margins weakly concave. Female. Coxa I strongly granulated, similar to male; coxa II granulation weaker than male, granules strong only on distal and anterior margins, endites almost smooth; coxa III smooth except for narrow strip of granules along proximal 3/4 of anterior margin; coxa IV with granulation similar to male but slightly weaker, strong granulation on anterior and proximal posterior margins; coxal macrosetae: I 4– 6, II 8, III 5–6, IV 1; sternum similar to male, granulate with larger median pit, 2 setae; genital opercula smooth except for weak granulation along outer anterior margin, 3–5 macrosetae.

Pectines ( Figs. 195 , 197 , 199 , 201 ). Basal piece with anterior margin concave, with deep median pit or groove; surface in male nearly flat, weakly shagreened, bearing 5 setae, in female strongly biconcave posteriorly, granulated in depressions and along posterior margin, bearing 7 setae; pectines with 3 marginal lamellae, 7–8 middle lamellae, extending to distal end of coxa IV in male, falling short of distal end in female; marginal and middle lamellae with moderate cover of short macrosetae; fulcra with 1–4 fine macrosetae (mostly 3–4); teeth of similar length in both sexes, tooth counts: ♂ 19/20, ♀ 19/19.

Hemispermatophore ( Figs. 248–251 , 331 ). Flagelliform, trunk elongate, ca. 6.4 times length of capsule region; flagellum with short pars recta bearing anterior marginal lamella, longer pars reflecta gradually tapering to cylindrical hyaline filament; sperm hemiduct tripartite, posterior lobe large, laminate, median lobe small, acuminate, anterior lobe of intermediate length; posterior margin of median lobe overhanging posterior lobe, the two lobes fused along median lobe carina; basal lobe a low, broad, axially oriented, curved scoop, with posterior-facing concavity, proximally angled in posterior direction, distally confluent with median lobe carina.

Mesosoma ( Figs. 194–201 , 334 ). Tergites: pretergites smooth, with weak, fine corrugations on posterior margins; tergites I–VI with lateral areas of coarse granulation in central and posterior parts, broken by smooth transverse patches, anterior lateral and medial areas heavily shagreened, posterior margins of sclerites rimmed by regular rows of granules; tergite I without distinct carinae, II with weak traces of median or median plus paired lateral carinae; tergites III–VI tricarinate with anteriorly divergent, granulate carinae which become stronger on more posterior tergites; granulation and carination pattern of female similar to male but much weaker; tergite VII with 5 carinae, median carina a weak granulated hump, lateral carinae strongly granular, inner lateral carinae anteriorly divergent, intercarinal areas with sparse or moderate density of coarse granules, smoother in male; all tergites lacking macrosetae; sternites: male: sternites III–V lacking carinae, medially smooth, weakly shagreened anterolaterally, III densely shagreened on surface covered by pectines; sternites IV– VI with weak, smooth remnants of outer lateral carinae near posterior margins adjacent to spiracles, VI with weak, smooth remnants of inner lateral carinae; sternites IV–VI with wide, posteromedian smooth patch; posterior margins of sternites III–VI with fringe of small, non-contiguous, digitate denticles; sternite VII smooth except for sparse fine granulation on outer lateral areas, median carinae weakly granulose, nearly smooth, lateral carinae strongly granulose; carinae confined to posterior 2/3 of sternite, only median pairs extending to posterior margin; non-marginal macrosetae: III 20 along edges of pectinal contact area, IV 10, V 7, VI 6, VII 6 including 4 stereotypic isolated macrosetae near outer anterior ends of carinae; female: sternite III smooth except for finely shagreened areas on surface covered by pectines; sternites IV–VI smooth except for very weakly shagreened anterior edges adjacent to pre-sternite borders; sternite VII smooth medially and anteriorly, sparsely granulate on mediolateral and lateral intercarinal surfaces; carinae obsolete on sternite III, reduced to smooth posterior wrinkles on medial sides of spiracles on IV–VI; posterior marginal denticles of sternites III–VI much smaller than in male; sternite VII with two pairs of welldeveloped smooth or weakly granular carinae, sparse granulation on mediolateral and lateral surfaces; nonmarginal macrosetae: III 26, IV 12, V 6, VI 7, VII 6; mesosoma wider in female than male.

Metasoma ( Figs. 194–195 , 198–199 , 252–257 ). Length about equal to prosoma and mesosoma, metasoma + telson L/ carapace L ♂ 5.33, ♀ 5.27; segments moderately robust; carination: segments I–IV with 10 complete carinae, IV with lateral median carinae weaker than I–II but distinct; segment V with 7 carinae in male, 5 carinae in female (ventrosubmedian carinae indistinct); carinae on segments I–IV uniformly granulate, except for nearly smooth ventromedian and ventrolateral carinae on metasoma I of female; ventrolateral carinae on V with granules gradually increasing in size, from finer anteriorly to coarser posteriorly; segment V with ventromedian carina marked by series of coarse granules, bifurcating in posterior half, ventrosubmedian carinae of male marked by series of coarse granules in anterior half, breaking up in posterior half, of female indistinct with coarse granules occupying broader longitudinal strips; lateral anal margin with 2 blunt granules or lobes, ventral anal margin with 17 (♂) or 20 (♀) granules; intercarinal surfaces: lateral and ventral aspects of segments I–IV mostly smooth with sparse fine granulation or isolated granules, except for denser fine granulation on ventral aspect of female metasoma VI; dorsolateral and lateral surfaces of segments II–VI rugose in female, weakly rugose in male; segment V of male with sparse granulation on lateral and ventral surfaces, of female with sparse granulation on lateral surface, denser granulation on ventral surface, lateral surface rugose in female, weakly so in male; dorsal surfaces of all segments smooth in both sexes; setation: all segments equipped with scattered long, curved, golden macrosetae on all aspects, most located near or on carinae, setae of similar length in both sexes; metasoma V with 5–6 macrosetae along dorsolateral margins.

Telson ( Figs. 194–195 , 198–199 , 252–257 ). Vesicle smooth dorsally and laterally, mostly smooth ventrally except for a few granules at anterior end; small indentations at setal insertion points; bulbous, with steep posterior slope, subaculear tubercle absent, but a slight ridge indicates trace of tubercle; several long macrosetae on lateral and ventral surfaces; aculeus slightly shorter than vesicle.

Pedipalps ( Figs. 202–243 ). Male ( Figs. 202–213 , 226–228, 232–235, 238–240 ). Femur: L/ W 3.02; dorsointernal and dorsoexternal carinae strong, ventrointernal carina moderate, all with regular coarse granulation; external carina strong, nearly smooth with isolated coarse granules associated with setal insertion points; internal carina moderate, with isolated medium to coarse granules; dorsal surface faintly shagreened, nearly smooth, other surfaces smooth; 8–10 accessory macrosetae on distal external surface; patella: L/ W 2.90; internal, dorsointernal and dorsomedian carinae moderate, weakly granulated, nearly smooth; dorsoexternal carina weak, smooth; external carina moderate, smooth; other carinae obsolete, ventromedian and ventroexternal carinae barely visible as smooth traces of thickened integument; intercarinal surfaces smooth; chela: slender, L/ W 4.27, all carinae obsolete, surface smooth with sparse macrosetae and microsetae; 9–10 primary denticle subrows on movable fingers, 8 on fixed fingers, total count of non-enlarged primary denticles on movable fingers 45/48, on fixed fingers 45/46; denticle subrows except proximal flanked by internal and external accessory denticles, 8–9 internal or external accessory denticles on movable finger, 7–8 on fixed finger. Female ( Figs. 214–225 , 229–231, 236–237, 241– 243 ). Femur: more robust than male, L/ W 2.67; carination and surface texture similar to male; 9–11 accessory macrosetae on distal external surface; patella: more robust than male, L/ W 2.56; dorsointernal and dorsomedian carinae smooth, internal carina with weaker granulation than male, other carinae similar to male; intercarinal surfaces smooth; chela: more slender than male, L/ W 4.61, all carinae obsolete, surface smooth with sparse macrosetae and microsetae; 9–10 primary denticle subrows on movable fingers, 8 on fixed fingers, total count of non-enlarged primary denticles on movable fingers 52/53, on fixed fingers 41/58; 9 internal or external accessory denticles on movable fingers, 8–9 on fixed finger. Trichobothriotaxy: orthobothriotaxic, type Aβ ( Vachon, 1974) ( Figs. 226–243 )

Legs ( Figs. 194–195 , 198–199 , 244–247 ). Inferior carinae finely denticulate on femur I–III, finely crenulate on femur IV; other carinae on femora finely granulate; prolateral surfaces of femora sparsely shagreened; patella II–IV with weakly denticulate inferior carinae, other carinae smooth, prolateral surfaces smooth; tibia III–IV with spurs; retrolateral tarsal spurs simple, prolateral tarsal spurs basally bifurcate; basitarsi I/II/III with 8/11/12–13 long retrosuperior macrosetae arranged in bristle-combs; ventral surface of telotarsi with dual rows of long, fine macrosetae, but dual row condition may be confined to only basal portion on basitarsi I–III, leaving a single file of setae in distal portion (cf. Pocock, 1895: 295); tarsal ungues moderately long.

Measurements. See Table 7 .

Variation. A second, smaller female (35 mm, subadult?) from Khamis Mushayt, Saudi Arabia (AMNH) was examined, and did not differ significantly in key diagnostic characters from the larger adult female (48 mm) from Dhofar described here (see also description of that specimen in Hendrixson, 2006). The specimens examined match very well the excellent original description and plates of Pocock (1895), for material collected from the Hadramaut in Yemen. Pocock noted variation in fuscous markings on proximal leg segments, and on carinae of pedipalp femur and patella. The lectotype female (ZMUH, photograph examined) appears to be an immature or juvenile instar (27 mm). It has more slender pedipalp segments, which is typical of immature Xenobuthus (e.g. in juvenile X. xanthus sp. n., cf. Figs. 266 vs. 270).

DISTRIBUTION. The distribution apparently covers the mountainous plateau region of the southwestern Arabian Peninsula, ranging from Asir highlands of Khamis Mushayt ( Saudi Arabia), through the Hadramaut of Yemen, to the Nejd Desert in Dhofar, Oman. A similar range of distribution is seen in other scorpions that inhabit the mountain ranges tracking the west to southwest coast of the Arabian Plate, e.g. Leiurus haenggii Lowe et al., 2014 , and Microbuthus kristensenorum Lowe, 2010 .

ECOLOGY. The male and female described here were both collected from the edge of a small sandy wadi in the arid Nejd Desert region (580 m a.s.l.), north of the Jabal Qara mountains in Dhofar. Scorpions that occurred together with X. anthracinus were: Compsobuthus acutecarinatus ( Simon, 1882) , Hottentotta salei ( Vachon, 1980) and Leiurus macroctenus Lowe et al., 2014 .

Figures

Figure 338. Map of records in the Arabian Peninsula of Butheolus and Xenobuthus gen. n. Symbols show locations of collection records of species examined in this study. B. gallagheri: black circles; B. harrisoni: orange circles; B. thalassinus: cyan circles; B. villosus: light green circle; X. anthracinus: magenta squares; X. xanthus: yellow squares. Locality data are from specimens examined, except for the type locality and two additional published records of B. thalassinus. The indefinite type locality of X. anthracinus (Hadramaut “by the way”; Pocock, 1895) is not plotted. Map scale: 150 km.

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 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 202–225: Pedipalp of Xenobuthus gen. n. anthracinus (Pocock, 1895). Figs. 202–213. Male (♂). Dorsal (202–204), external (205–207), ventral (208–210) and internal (211–213) aspect of femur (202, 205, 208, 211), patella (203, 206, 209, 212) and chela (204, 207, 210, 213). Figs. 214–225. Female (♀). Dorsal (214–216), external (217–219), ventral (220–222) and internal (223–225) aspect of femur (214, 217, 220, 223), patella (215, 218, 221, 224) and chela (216, 219, 222, 225). Both sexes with same locality data as in Table 7. Scale bars: 1 mm.

Figures 226–243: Trichobothrial maps and chela finger dentition of Xenobuthus gen. n. anthracinus (Pocock, 1895). Male (♂): dorsal (226), external (227) and ventrointernal (228) aspect of chela; dorsal (232) and external (233) aspect of patella; dorsal (238), external (239) and internal (240) aspect of femur; dentition of movable finger (MF) (234) and fixed finger (FF) (235). Female (♀): dorsal (229), external (230) and ventrointernal (231) aspect of chela; dorsal (236) and external (237) aspect of patella; internal (241), dorsal (242) and external (243) aspect of femur. Both sexes with same locality data as in Table 7. Scale bars: 1 mm (♂, ♂ dentition, ♀).

Figures 244–247: Leg tarsi and tibiae of male Xenobuthus gen. n. anthracinus (Pocock, 1895). Retrolateral aspect, left leg I (244), II (245), III (246), IV (247) tibia, basitarsus and telotarsus. Same locality data as male in Table 7. White light illumination. Scale bar: 1 mm.

Figures 248–251: Hemispermatophore of Xenobuthus gen. n. anthracinus (Pocock, 1895). Figs. 248–250. Capsule region of right hemispermatophore, anterior (284), convex (249) and posterior (250) aspects. Scale bar: 200 µm. In convex view (249), the capsule is compressed to show outlines of lobes. Fig. 251. Whole left hemispermatophore, convex aspect. Same locality data as male in Table 7. White light illumination. Scale bar: 1 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 258–261: Chelicerae of male Xenobuthus gen. n. anthracinus (Pocock, 1895) and X. xanthus sp. n. Figs. 258–259. X. anthracinus, right chelicera, dorsal (258) and ventral (259) aspect. Same locality data as male in Table 7. Figs. 260–261. X. xanthus sp. n., right chelicera, dorsal (260) and ventral (261) aspect. Holotype male. Scale bar: 500 µm.

Figures 326–329: Right lateral eye clusters of Xenobuthus gen. n. Figs. 326–327. X. anthracinus, adult male (326) and adult female (327). Figs. 328–329. X. xanthus sp. n., adult male (328) and adult female (329). Locality data as in Tab. 7. UV fluorescence. Scale bar: 100 µm, for all panels.

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).

Figures 266–267: Habitus of female Xenobuthus gen. n. xanthus sp. n. Fig. 266. Dorsal aspect. Fig. 267. Ventral aspect. Paratype female (♀), #2 in Table 7. Scale bar: 5 mm.