Trypanothacus barnesi, Lowe & Kovařík & Stockmann & Šťáhlavský, 2019

Lowe, Graeme, Kovařík, František, Stockmann, Mark & Šťáhlavský, František, 2019, Trypanothacus gen. n., a new genus of burrowing scorpion from the Arabian Peninsula (Scorpiones: Buthidae), Euscorpius 277, pp. 1-30: 5-21

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Trypanothacus barnesi

sp. n.

Trypanothacus barnesi   sp. n.

( Figs. 1–42, 47–77, 84–87, 107–108, 111–118, Tables 1–2)


TYPE LOCALITY AND   TYPE DEPOSITORY. Oman: Dhofar Province, S of Shalim , 18.041070°N 55.612262°E GoogleMaps   , FKCP.

TYPE MATERIAL EXAMINED. Oman: 1♀ (paratype), Yalooni, Jiddat Al Harasis , 19°57'N 57°06'E GoogleMaps   , XII.1988, ONHM 1186, Yalooni 185   , NHMB; 1♀ (paratype), Dhofar, Thamarit , 17°39'N 54°02'E, 10.XI.1989, leg. I. A. J. Brown GoogleMaps   , ONHM 1416   , NHMB; 3♂ (paratypes), Thumrait , wadi area SE of Thumrait in slightly raised sedimentary plateau, under sheet wood, and in aircraft shelter, 17°42'N 53°59'E GoogleMaps   , VII.1997, leg. J. N. Barnes, NHMB, GLPC, ONHM; 1♂ subadult (paratype), Thumrait airfield, in aircraft shelter, 17°42'N, 53°49'E, 23. GoogleMaps   VII.1998, leg. J. N. Barnes, NHMB; 3♂ (holotype No. 1121 and 2 paratypes No. 1594), S of Shalim, 18.041070°N 55.612262°E, 6.IX.2016, 21:00–23:00 h, full moon GoogleMaps   , UV detection, FKCP, GLPC (hemispermatophore); 1♀ (paratype), same locality as holotype, 27–28.X.2017, 23:00–01:00 h, 62% moon GoogleMaps   , UV detection, leg. M. Stockmann, FKCP.

OTHERMATERIALEXAMINED. Oman:1juv,nearThamarit, Dhofar, under rock, 450 m a.s.l., 17°40'N 54°02'E, 22. III GoogleMaps   .1980, leg. J. N. Barnes, Sc 74, Barnes 36, MNHN RS8787 View Materials ; 1 ♀   fragment, Yalooni, Jiddat Al Harasis , found dead on level limestone rock and sand, 19°56'N 57°06'E, 10.XI.1980, leg. M. D. Gallagher, MDG6020, NHMB GoogleMaps   .

DISTRIBUTION. OMAN. Ranging from the inland plateau of Jiddat al-Harasis in central Oman to the Nejd Desert of Dhofar, southern Oman.

ETYMOLOGY. The specific epithet is a patronym dedicated to naturalist J. Neil Barnes, Airworks Ltd, Salalah, Oman, who first collected this species in 1980 from around the Thumrait airbase, and contributed other important specimens of Oman scorpions.

DIAGNOSIS. A member of Trypanothacus   gen. n. differentiated from its congener as follows: pedipalp femur L/W ♂ 2.6–3.1, ♀ 2.5–2.7, patella L/W ♂ 2.5–2.7, ♀ 2.4–2.7, chela L/W ♂

3.5–4.0, ♀ 4.4–4.6; metasoma IV L/D ♂ 2.0–2.2, ♀ 1.9–2.0, V L/D ♂ 2.7–3.0, ♀ 2.5–2.9.

DESCRIPTION. Length of adults: ♂ 40–51 mm, ♀ 43–57 mm; habitus as shown in Figs. 1–4.

Coloration ( Figs. 1–10, 15–22, 29–42, 71–72, 84–87). Base color yellow or yellowish brown to orange; chelicerae yellow with or without reticulation, dentition reddish to black; median eyes may be surrounded by moderate fuscosity, with weak fuscosity extending forward towards lateral eyes; articular condyles of pedipalp chela fingers and legs reddish brown; macrosetae of body and appendages dark reddish brown; denticles on pedipalp chela fingers and aculeus of telson dark reddish brown.

Carapace ( Figs. 5–6, 11, 13). Trapezoidal, anterior margin straight or almost straight, with weak fine denticulation, 6–12 marginal macrosetae, bordered with row of coarse granules; surface with sparse to moderately dense coarse and fine granulation; anterior median carinae indicated by coarse granules, other carinae of carapace obsolete; lateral areas of interocular triangle with coarse granules, area between anterior median carinae smooth; median ocular tubercle smooth, except for a few posterior granules; median eyes large, well separated; posterolateral areas of interocular triangle, median postocular area and posterior marginal furrow smooth; posterior margin bordered by row of coarse granules; 5 lateral eyes (3 larger, 2 smaller; in ‘ type 5’ configuration of Loria & Prendini, 2014).

Chelicera ( Figs. 71–73). Fingers with typical buthid dentition ( Vachon, 1963); fixed finger with large distal denticle, one subdistal denticle and two basal denticles fused into bicusp, two denticles on ventral surface, one at level of bicusp, other slightly proximal to subdistal denticle; dorsal margin of movable finger with 5 denticles: one large distal denticle, medium-sized subdistal denticle, large medial denticle, and two small, partially fused basal denticles; ventral margin with 3 denticles: one large distal denticle, and two smaller denticles in medial and basal positions.

Mesosoma ( Figs. 1–4, 6, 8, 11–14). Tergites I–VI tricarinate with median carina and anteriorly diverging pair of lateral carinae; carinae coarsely granular, the lateral pair on the tergites I–II possibly indistinct; all carinae short with only ca. 2–5 granules, confined to posterior half or third of tergite; lateral flanks of tergites with sparse to moderately dense, coarse granulation on posterior half, posterior margins bordered with row of granules; other tergite surfaces smooth to faintly shagreened; tergite VII pentacarinate, median carina a granulated hump, lateral carinae well developed, coarsely granular; posterior margin of tergite VII without rim of granules, intercarinal surfaces smooth or with sparse, coarse granulation; coxae mostly smooth, with few sparse isolated patches of granules, coxal margins smooth or with weak granulation; sternum subtriangular, smooth, with deep posteromedian pit; sternites with smooth surfaces and posterior margins, III–VI without carinae, VII with 2 pairs of weak to moderate, smooth to granulated carinae; sternal chaetotaxy: sternite III-VI posterior margins conspicuously setose, bearing approximately 20 macrosetae, III bearing about a dozen macrosetae on medial surface, IV-VII with 4 medial and 2 lateral macrosetae, VII with single anterior macroseta on each of the 4 carinae, plus a lateral pair; pectines with anterior margins extending to midpoint (♂) or to approximately proximal 1/6 (♀) of trochanter IV, with 3 marginal lamellae, 4–9 middle lamellae; lamellae and fulcra bear numerous short, fine, dark macrosetae; pectine basal piece and genital opercula smooth with fine macrosetae; pectinal tooth counts, ♂ 22–26, ♀ 17–21.

Hemispermatophore ( Figs. 74–77). Flagelliform, moderately elongated, trunk ca. 6 times length of capsule region as measured from proximal flagellum base; flagellum well separated from capsule lobes, pars recta short, ca. 2.7 times length of capsule and lobes, 50% length of trunk, with weak fin along anterior margin; pars reflecta long, narrow, gradually tapered, hyaline, 0.88 times length of trunk; capsule region with 4 lobes arranged in ‘3 +1’ configuration, posterior lobe the largest, a lanceolate lamina with pointed apex; median lobe smallest, acuminate, attached to base of posterior lobe along short, suture, but a sclerotized carina not clearly visible; anterior lobe of intermediate length, laminate, apically acuminate; basal lobe a small, rounded knob-like process situated well proximal from point of splitting of posterior and median lobes.

Metasoma and telson ( Figs. 15–28). Metasoma I with 10 granulated or crenulated carinae, median lateral carinae complete, ventromedian carinae may be weak or obsolete in males; II–III with 10 granulated or crenulated carinae, median lateral carinae incomplete, indicated by ca. 5–14 granules on posterior 1/3 to 2/3 of segment; ventromedian and ventrolateral carinae on II–III stronger in females, with conspicuously enlarged, dentate or lobate granules, increasing in size posteriorly; coarsely granulose anterior ventral margins present on III–IV; IV with 8 granulated or crenulated carinae; V with 5 carinae, dorsolateral carinae weak, granulated, ventrolateral carinae strong, irregularly crenulated with several enlarged, corresponds to posterior width), depth (D), standard deviation (sd).

lobate granules that become larger posteriorly; ventromedian carina of V composed of series of large granules interspersed with finer granulation; intercarinal surfaces of I–IV smooth or almost smooth dorsally, almost smooth or with sparse granules dorsolaterally and laterally; ventrolateral and ventral surfaces of I smooth, of II–III almost smooth with sparse fine granulation, of IV with weak, fine granulation or shagreened; segment V smooth dorsally with scattered small granules, with weak fine granulation laterally, slightly denser fine granulation ventrally; lateral anal arch divided into 2–3 lobes; ventral anal arch armed with regular series of ca. 5–7 coarse granules; telson with distinctly bulbous vesicle bearing coarse granules on ventral surface; granulation more dense in males, more sparse in females, with smooth areas; lateral surface of vesicle with sparser granulation, dorsal surface smooth; aculeus equal to or shorter than vesicle in length, moderately curved; subaculear tubercle absent; chaetotaxy: metasomal segments and telson sparsely setose; long macrosetae located along carinae on metasoma I–IV, typically 2–3 per carina; V with several setae along dorsolateral carina, ca. 6 setae in longitudinal series on lower lateral surface, several setae on ventral surface associated with enlarged granules; telson vesicle with a dozen or more long macrosetae scattered over ventral and ventrolateral surfaces.

Pedipalps ( Figs. 29–40, 47–70). Segments short, robust; femur with 3 strong, granulated carinae: dorsoexternal, dorsointernal, and ventrointernal, other carinae obsolete; dorsal, lateral and ventral surfaces smooth except for few small solitary granules, internal surface smooth except for several solitary coarse granules; distal external surface with group of ca. dozen macrosetae; patella with 7 carinae: dorsointernal, internal and ventrointernal carinae coarsely granulose, internal carina with sparse, non-contiguous granules; dorsomedian and dorsoexternal carinae weak, smooth or almost smooth with traces of coarse granules; external and ventroexternal carinae weak, smooth; ventromedian carina obsolete, indicated by series of few granules; all intercarinal surfaces smooth; setation very sparse, with few large solitary macrosetae on carinae; chela smooth, carinae obsolete with residual traces of carinae in females; few large macrosetae present, ventral surface of movable finger with numerous short macrosetae, increasing in density distally; dentate margin of movable and fixed fingers with 7–8 rows of granules, each with a single external and internal accessory granule, and 3–6 subterminal granules (typically 3–4 of them enlarged); trichobothrial pattern orthobothriotaxic type Aβ, chela fixed finger with db near base of fixed finger.

Legs ( Figs. 1–4, 9–10). Legs with long femora and robust patellae, tibiae and tarsi; femora with few solitary macrosetae; tibiae I–III with dorsal (retrosuperior) linear series of long macrosetae (= tibial ‘bristle comb’, 8–12 setae in sample of N=13 leg III segments), and shorter macrosetae on other surfaces; basitarsi I–III compressed, with two linear series of shorter ventral (proinferior and retroinferior) macrosetae, single linear series of longer dorsal (retrosuperior) macrosetae (= basitarsal ‘bristle comb’, 17–23 setae in sample of N=12 leg III segments); macrosetae long and thin in both sexes; leg IV without basitarsal compression, longer than legs I–III, long macrosetae more sparse, not arranged in linear series; leg I–IV femora and patella with indications of 4–6 carinae, which are usually obsolete; paired ventral carinae on femora granulate or denticulate, prolateral surfaces of femora with weak granulation localized on inferior proximal areas of I–II; tibial spur on leg IV strong, longer than spur on leg III; prolateral pedal spurs basally bifurcate, setose (leg III spur with 6–8 short macrosetae in sample of N=10 segments); retrolateral pedal spurs simple.

Sexual dimorphism. Compared to females, males have longer pectines ( Figs. 2, 4, 7–8, 12, 14), higher pectinal tooth counts, and broader pedipalp chelae; chela fingers are straight in both sexes, and males lack recess or scalloping of the proximal dentate margins ( Figs. 29–31, 39–40, 47–50, 59–62, Table 1); the male telson vesicle is slightly less bulbous, granulation on the carapace and tergites is more dense; sternite VII carinae of the male are weaker and smoother, and metasomal carinae are not as robust as in females, especially the ventromedian carinae on metasoma II–III; intercarinal granulation is more dense on the male metasoma. For data on morphometric sexual dimorphism, see under species diagnosis and Table 2.

Measurements. See Table 1.

Morphometric variation. See Table 2.

Karyotypes ( Figs. 111–113). We analyzed two males (holotype and paratype from type locality) using standard cytogenetic methods (e. g. Kovařík et al., 2009). The diploid number of both specimens is 26 chromosomes ( Figs. 111–112). We did not observe chiasmata during male meiosis and centromeres on chromosomes. These characteristics are typical for the scorpions from the family Buthidae   (e.g. Mattos et al., 2013). The chromosomes of Trypanothacus barnesi   sp. n. gradually decrease in length from 8.69 % to 5.92 % of the halpoid set ( Fig. 113).

AFFINITIES. In the diagnosis, we separated T. barnesi   sp. n. from its similar allopatric congener, T. buettikeri   comb. n. by measurable differences in the shapes of the pedipalp and metasoma, indicated by non-overlapping ranges of morphometric ratios. T. barnesi   sp. n. is a less robust, more slender scorpion with narrower pedipalps and posterior metasomal segments. Only limited numbers of specimens of T. buettikeri   comb. n. were available to us for study and confirmation of species identity, and additional material may extend morphometric variation in this species. However, samples from around the type locality and a well separated western site (Wadi Turabah) both have robust segments, so the morphometric diagnosis is likely to remain valid. We hypothesize that T. barnesi   sp. n. and T. buettikeri   comb. n. are sister species that diverged after southern and northern populations were isolated from each other by formation of the Rub‘ al Khali (Empty Quarter) dune system during the Quaternary. Soft unstabilized sands may be an effective physical barrier blocking dispersal of ancestral Trypanothacus   adapted to firmer substrates. This model of vicariant speciation by dune barriers has also been suggested for Leiurus macroctenus   , a sympatric scorpion that may have substrate preferences similar to those of T. barnesi   sp. n. ( Lowe et al., 2014).

COMMENTS ON LOCALITIES AND LIFE STRATEGY.The type locality is a flat desert plateau along route 42, the road between Shalim and Ash Shuwaymiyyah near the coast. The substrate consists of reddish soil alternating with bare rock, clay and sand. Shrubs and trees are scattered and provide only slight patches of humidity in an otherwise arid area. There are few if any loose rocks, except in disturbed areas where stones may be piled near the road by construction activity. The weather on both collection dates was mild at night (ca. 22 °C) with high humidity, barely any wind and no clouds to block the bright moon. At night, Trypanothacus barnesi   sp. n. was the most active scorpion in this area. Males were highly active on open ground, whilst females were resting in ambush position at the entrances of their burrows. The burrows were located in sandy areas at the bases of shrubs or rocks, and only rarely on open ground. Only small juveniles to medium-sized immatures were found under rocks without a burrow. Far more males than females were observed on both nights. Remarkably, many were observed actively foraging and feeding on termites, close to the insect nests and trails. Several termites were captured and consumed simultaneously by one scorpion. Other potential prey, including various insects ( Formicidae, Heteroptera, Coleoptera   , Blattodea   , lepismatids) and arachnids (ticks, spiders and pseudoscorpions) were abundant in the area. Mobile white mites were observed on many individuals of T. barnesi   sp. n. (cf. Fig. 85, an adult female with mites on tergite II and carapace), but not on other arthropods in this habitat. Some individual scorpions were densely covered with mites, whereas others bore only a few. Other species of scorpions found in this area were: Androctonus crassicauda (Olivier, 1807)   , Leiurus macroctenus Lowe, Yağmur & Kovařík, 2014   , Femtobuthus shutuae Lowe, 2010   , Nebo sp.   , and Compsobuthus acutecarinatus (Simon, 1882)   .

Both the type locality and the paratype collection site of Yalooni (Arabian Oryx sanctuary) are located on the Jiddat Al Harasis, an extensive stony limestone plateau in central Oman. The region is ecologically classified as coastal fog desert. Moisture is deposited by condensation of humid air swept inland from the sea during the summer monsoon (khareef). This sustains local vegetation and animal populations, including the scorpion fauna. The other collection sites around Thumrait are located on the Nejd Desert plain in the rain shadow of the Jabal Qara mountains. Without monsoon mist, the terrain is more arid, consisting mostly of sand and gravel flats with sporadic rocky outcrops. Drainage in some shallow wadi beds supports scattered trees and shrubs, with xerophytic herbs and grass as low ground cover. In this area, T. barnesi   sp. n. was reported to be present but uncommon (J.N. Barnes, personal communication, 05.VII.1992, Figs. 86– 87). Other scorpions recorded from there were: Androctonus crassicauda   , Leiurus macroctenus   , Orthochirus innesi Simon, 1910   and Xenobuthus anthracinus (Pocock, 1895)   . The first two of these were the most common.

CAPTIVE REARING AND BREEDING.Two medium-sized immatures (1♂, 1♀) were reared to maturity in captivity. They were housed in 11 cm × 11cm × 6 cm plastic boxes with two perforated sides, filled with a thin layer of loose sand, and were provided with a small shelter. A burrowing substrate was not provided in order to more easily observe behavior. Average temperatures in summer were 32°C (day) and 24°C (night). In winter, a mild diapause was simulated with temperatures of about 25°C (day) and 20°C (night). One corner of the box was slightly moistened by spraying water once a week to provide drinking water. The water completely evaporated in the following day and conditions were kept dry for the rest of the week to prevent mycosis. Insects ( Thermobia domestica   , Shelfordella lateralis   and Acheta domesticus   ) of adequate sizes were offered as prey.

Three weeks after attaining maturity, the female was mated (XI. 2017). Upon being introduced to the female, a male immediately initiated courtship without preliminary behavior like juddering. The promenade à deux began with the male grasping the female pedipalps, and continued with a series of back and forth pulling motions by both sexes ( Fig. 114). Male pectinal movements occurred almost continually, without lengthy interruptions. Remarkably, both sexes engaged in sand scraping with legs I–III ( Fig. 115), sometimes settling their bodies into depressions they excavated in the loose sand to rest for a few seconds ( Fig. 116) before continuing the promenade à deux. Several episodes of cheliceral massage lasting several seconds were observed ( Fig. 117), but there was no sexual sting. After 17 min 48 s, a spermatophore was deposited by the male on a flat rock ( Fig. 118) and taken up by the female 3 s later. Both individuals then immediately separated, and the female began to display aggressive behavior towards the male, but did not attempt mate cannibalism. The female was subsequently reared under the same conditions as described above, and gave birth to 23 juveniles in the following season (VII. 2018). These were separated from the parent one week after their first ecdysis, and successfully reared under the same conditions as the parental generation.


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