Lissothus occidentalis Vachon, 1950

Stockmann, Mark, Turiel, Carlos, Althoff, Felix, Lowe, Graeme & Kovařík, František, 2016, First report of Lissothus occidentalis Vachon, 1950 (Scorpiones: Buthidae) from Morocco and Western Sahara, with notes on ecology and captive breeding, Euscorpius 235, pp. 1-12 : 1-11

Lissothus occidentalis Vachon, 1950

( Figs. 1–45, Table 1)

Lissothus occidentalis Vachon, 1950: 406 (1952a: 412) : Vachon, 1952b: 172–177, figs. 1–7; Vachon, 1953: 1021, fig. 11; Vachon, 1974: 909, fig. 41; Fet & Lowe, 2000: 158 (complete reference list until

2000); Lourenço, 2001: 52–54, figs. 1, 3; Lourenço & Sadine, 2014: 417, fig. 1.

TYPE LOCALITY AND TYPE DEPOSITORY. Mauritania, Akjoujt , MNHN.

MATERIAL EXAMINED. Morocco, Souss-Massa region , Akka, 29°23'03"N 8°16'04"W ( Figs. 35–37), 20.IX.–1. X.2013, 1♂ 2♀ ( Figs. 1–34), FKCP, V .2015– XI.2016, 10♂ 3♀5♀ ims., still alive, MSGC, leg. Omar Hassan , at sandy plains close to oasis, UV detection per night and under stones per day; Guelmim-Qued Noun region , North of Zag, 28°14'55.4"N 9°19'58.5"W ( Fig. 39), 4. – 14.X.2016, 2♂1♂ im., FKCP, leg. Omar Hassan , under stones at a sandy plain; Guelmim-Qued Noun region , Targa Wassay, 29°4'6.3"N 10°14'54.3"W, 152 m a.s.l, V .2009, 1♀, UV detection, CIBIO SC529 . Western Sahara, Es Semara Province , Smara, 26°57'22.1"N 11°39'47.7"W, V .2013, 1♂ im., UV detection, CIBIO SC2396 .

D IAGNOSIS. Total length 24–37 mm; coloration basically yellow to light brown with darker fuscous areas on metasomal segments IV– V and anterior part of interocular triangle of carapace; carapace trapezoidal, in lateral view preocular area not distinctly inclined towards anterior margin; surface of carapace finely granular, without carinae; tergites only with single median carina; pectines with fulcra, hirsute; pectine teeth 15–18 in male, 14–16 in female; sternites III– VI lacking carinae; sternum subtriangular; metasoma II as wide as other metasomal segments; metasoma I–III with 10 smooth carinae indicated or absent; metasoma IV smooth without obviously developed carinae; metasoma V with enlarged "lobate" dentition on ventrolateral carinae; telson tuberculate without subaculear tubercle, with short aculeus, shorter than vesicle; segments of metasoma I–III sparsely hirsute, IV– V with solitary seta only; dentate margin of movable finger of pedipalp with linear row of granules, divided into three non-imbricated rows by two slightly enlarged denticles; 2 internal accessory granules, 2 terminal, and 1 basal terminal granules present; trichobothrial pattern orthobothriotaxic type A; dorsal trichobothria of femur arranged in β- configuration; pedipalp patella with 7 external trichobothria; pedipalp chela with trichobothrium esb missing; pedipalp femur with trichobothrium d 2 missing; d 2 of pedipalp patella present; tibial spurs present on legs III–IV; shape of pedipalp and metasoma without sexual dimorphism.

Measurements. Male from Morocco, Akka (FKCP). Carapace L/Wp 2.6/2.6; pedipalp L 11.4; chela L 5.2; hand W 0.9; movable finger L 3.7 patella L/ W 3.4 /1; femur L/ W 2.8 /0.7; metasoma L 16; I.segment L/W/D 2.1/1.5/1.2; II.segment L/W/D 2.6/1.4/1.2; III.segment L/W/D 2.8/1.4/1.2; IV.segment L/W/D 3/1.4/1.2; V.segment L/W/D 3.1/1.4/1.2; telson L 2.4; vesicle L/ W 1.5 /1.2; aculeus L 0.9; total length L 28.8. Measurements in mm (L = length, W = width, Wp = posterior width, D = depth).

Hemispermatophore ( Figs. 30–34). Flagelliform, relatively stout, trunk 4.65 times length of capsule region. Flagellum well separated from capsule lobes, pars recta long, 0.65 times length of trunk, with gradually tapering fin along internal margin; pars reflecta long, narrow, hyaline, 1.17 times length of trunk. Capsule region with 4 lobes arranged in 3 + 1 configuration typical of the " Buthus " group ( Fet et al., 2005; Kovařík et al., 2 016): external lobe largest, a gently tapered lamina with rounded apex; median lobe smallest, sharply acuminate, with weak carina on internal margin; external and median lobes partially fused along a dark suture line or fine carina; internal lobe intermediate in size, laminate, gently tapered with pointed apex; internal and median lobes well separated by deep incision; basal lobe a small, distally projecting, hook-like process. Right and left hemispermatophores from the dissected male were similar in structure.

Vachon (1952b, fig. 6) showed the capsule lobes of the holotype male of L. occidentalis from Mauritania in a crude line drawing. That illustration differs from the hemispermatophores that we examined as follows: (i) the external lobe (= internal lobe of Vachon) is not distally rounded but terminates in a pointed apex; (ii) the median lobe is not as finely acuminate; (iii) the basal portions of external and median lobes are shown as overlapped but separate, not fused. We could not confirm whether these are genuine differences in the hemispermatophore of the holotype, which was unavailable for loan to the authors, but suspect that they may reflect errors or inaccuracies in illustration.

Notes on Ecology

L. occidentalis seems to be locally rare, but has a widespread distribution. Populations are small and dispersed. Their distribution is mostly limited to typical reg–desert formations. However, the record for Targa Wassay ( Morocco), does not correspond to the typical distribution and habitat, as this a loamy flat area surrounded by vegetated mountains close to the coast. Unfortunately we were not able to observe the habitat in Smara ( Western Sahara) and our own efforts to locate L. occidentalis in Targa Wassay were not successful.

Akka ( Figs. 35–37) is located in the south-eastern part of Morocco. The village and the small sand desert south of Akka is surrounded by mountains ( Fig. 35). Climatic conditions in the summer have temperatures close to 40 °C by day and ca. 22 °C at night with nearly no precipitation. Only the oasis and the riverbed (Arabic: Qued or Wadi) provide water and humidity in the dry summer season. In winter, temperatures rarely drop below 20 °C by day and 5 °C at night. Most precipitation occurs in the winter, with an average rainfall of 23–24 mm in November and December. Qued Akka and Oasis Akka are fertile with many date-palms and acacias. The Oasis is surrounded by farmland, and the small area in the south is typical sand desert. Rock cover is sparse on the plains, but the bases of the mountains provide more rocky habitat. Small, thorny shrubs occur widely but the area is not heavily vegetated. A female of L. occidentalis was found during the day under a larger rock on relatively loose sand one side of a street. The other side of the street was farmland ( Fig. 37). Two males and a female were found in the rocky and shrubby area between the mountains and the oasis ( Fig. 35) by UV detection. The female was feeding on a termite late at night ( Fig. 38). Termites seem to be the primary food source, because of infrequent occurrence of other suitable prey species. In addition, at this sandy plain near Akka, Compsobuthus sp. and Androctonus amoreuxi (Audouin, 1825) were recorded. Inside the oasis, Hottentotta gentili (Pallary, 1924) was observed on the date palms.

Zag is a village in the far south-east of Morocco, close to the borders of Algeria and the Western Sahara. The described habitat is located 25 km north of Zag. Climatic conditions are similar to those at Akka, but the environment is slightly different. Sandy flat areas are partially covered with large black rocks. Some of these rock areas are loamier than the surrounding environment and provide a substrate for scorpions to excavate burrows. The habitat is sparsely but consistently covered with small shrubs and some solitary trees ( Fig. 39). Three males of L. occidentalis were found under rocks, but none were found by UV detection at night. In addition, in this habitat Androctonus amoreuxi , Compsobuthus berlandi Vachon, 1950 and Buthacus sp. were recorded. Buthus mariefrancae Lourenço, 2003 was also observed here, but was mostly limited to the loamy rock areas.

Notes on Envenomation

During a field trip in the evening, the first author was stung on the left thumb by an adult male of Lissothus occidentalis . Slight local pain occurred im- mediately around the sting site, comparable with a honeybee sting. The pain faded after a few hours, leaving the thumb touch sensitive until the next morning. No further symptoms were observed, suggesting that the venom of this species probably only has mild clinical effects.

Notes on Captive Breeding and Rearing

Two adult pairs were each maintained in 20 x 20 x 1 0 (cm) (length x width x height) plastic boxes. Temperatures during the summer were ca. 30–32 °C (day) and ca. 22–24 °C (night). Hibernation conditions were simulated in the winter at ca. 22 °C (day) and 14–15 °C (night). To provide drinking water, a corner of the box was slightly moistened by spraying water once a week. The water completely evaporated during the next day. Three broods of two females were observed in captivity under these conditions during months 11 and 12. Numbers of offspring varied from 2 – 14 ( Tab.1).

Gestation of both females was about 2–3 months during the active phase in the summer. Hibernation was simulated for about 4 months and prolonged the gestation to 9–11 months. Spermatophores were absent and mating activity was not observed between broods. This indicates the ability to store sperm and produce several broods after mating. This hypothesis is further supported by the extremely short gestation period of ca, 2 months during the summer.

After leaving the mother, instar 2 individuals were separated into 11 x 11 x 6 (cm) plastic boxes with two perforated sides. The first three litters from 2014 were reared under the same temperature conditions as the adults. However, moisture conditions were different: one third of the box was kept mainly moist, to prevent dehydration of the small juveniles. The substrate dried out for a maximum of one day. Under these conditions most juveniles did not molt to instar 3, and died before or right after their hibernation period. Only 3 specimens molted to instar 3 and instar 4 after hibernation, but died in 2015.

The three litters from 2015 were reared under different conditions. The temperature was decreased to 27–28 °C during the summer and less water was provided. A quarter of the substrate was moist for 3 days, and dry for the rest of the week. About 50 % of the juveniles molted to instar 3 in Autumn of 2015.

A mild hibernation was simulated from November 2 015 to March 2016. The growth rate of the juveniles seemed too low for a small, fast reproducing (i.e. opportunistic, or r-selected) buthid scorpion. To induce molting and faster growth, conditions were further modified after hibernation. The temperature was elevated to 30– 31 °C by day and ca. 22–23 °C at night during the summer. Moisture was further reduced. The substrate was mostly dry, similar to the conditions of the adult specimens. When juveniles rejected food and seemed to molt soon, more humidity was provided by keeping one third of the substrate moist for 4–5 days. In parallel, the temperature was elevated to 36 °C on one side of the box. Under these warmer and more humid conditions, juveniles molted within 1–2 two weeks. After molting, the conditions were switched back to the previous standard temperature and humidity. It seemed important to provide food shortly after the hardening of the exoskeleton, for water and nutrient supplementation. Small-sized Thermobia domestica were constantly present in the boxes as a food source. On average, males attained maturity at instars 5–6, and females at instar 6.