Scorpioninae Latreille, 1802

Prendini, Lorenzo & Loria, Stephanie F., 2020, Systematic Revision Of The Asian Forest Scorpions (Heterometrinae Simon, 1879), Revised Suprageneric Classification Of Scorpionidae Latreille, 1802, And Revalidation Of Rugodentidae Bastawade Et Al., 2005, Bulletin of the American Museum of Natural History 2020 (442), pp. 1-480 : 442-444

Subfamily Scorpioninae Latreille, 1802

Scorpionides Latreille, 1802: 46 , 47 (part), type genus: Scorpio Linnaeus, 1758 ; 1804: 110 (part); 1806: 130 (part); 1810: 116, 118 (part); Leach, 1814: 412; 1815: 390; Latreille, 1817: 310 (“tribe,” i.e., part); 1825: 310 (“tribe”; part); Sundevall, 1833: 29 (part).

Scorpionini: Peters, 1861: 510 (part); Lankester, 1885: 379 (subfamily, part); Pocock, 1893: 305 (subfamily); Kraepelin, 1894: 24 (subfamily); Laurie, 1896b: 128 (subfamily); Pocock, 1900a: 84; Rossi, 2016a: 20, 26.

Scorpioninae : Kraepelin, 1899: 106; 1901: 270; 1905: 344; Birula, 1917a: 161; 1917b: 59; Kopstein, 1921: 128; 1926: 111; Pavlovsky, 1924a: 78, 79; 1925: 192; Werner, 1934: 277; Kästner, 1941: 233; Millot and Vachon, 1949: 428; Bücherl, 1964: 59; Lamoral, 1979: 668; Levy and Amitai, 1980: 102; Tikader and Bastawade, 1983: 518; Lourenço, 1989: 174; Sissom, 1990: 131; Fet, 2000: 430, 431; Indra, 2001: 56; Bastawade, 2002: 295; Soleglad and Fet, 2003a: 56, 86, 88, 112–115, 117, 120, 140, tables 9, 11, appendix A; Prendini et al., 2003: 185, 186, 212, table 1; Bastawade, 2004: 290; Bastawade et al., 2004: 47, 57; Bastawade, 2005: 417; Bastawade et al., 2005: 72, 82; Fet and Soleglad, 2005: 9, 13; Soleglad et al., 2005: 1, 2, 3, 5, 6, 8, 20, 21, 26, 28–30, 33–35, tables 1, 6, figs. 72–74; Thulsi Rao et al., 2005: 3, 8; Sureshan et al., 2007a: 2906; 2007b: 52; Bastawade and Borkar, 2008: 218; Indra, 2009: 141; Kovařík, 2009: 1, 2, 5, 17; Prendini, 2009: 17, 32, 34, 40, tables 1, 3, fig. 6; Veronika et al., 2013: 72; Rossi, 2016a: 18, 20, 22, 26; Kovařík et al., 2017b: 1, 6; Esposito et al., 2018: 115, appendix 1.

Scorpionaria: Birula, 1917a: 161 (“tribus”).

DIAGNOSIS: Scorpioninae can be separated from Heterometrinae and Pandininae by means of the following characters ( Prendini et al., 2003): absence of a stridulatory organ, comprising a “rasp” (granular tubercles) and “scraper” (stridulatory setae or scaphotrix), on opposing surfaces of the coxae of the pedipalps and the first pair of legs; digital carina of pedipalp chela usually distinct; counts of pro- and retroventral spiniform macrosetae increasing from telotarsi I and II to III and IV. Scorpioninae can usually be further separated from Heterometrinae by means of the following character: sternite VII with paired ventrosubmedian and ventrolateral carinae. Scorpioninae can be further separated from Pandininae by means of the following character: pedipalps orthobothriotaxic, with 26 trichobothria (patella with 13 trichobothria in e series and 3 trichobothria in v series; chela with 4 trichobothria in V series and 2 trichobothria in i series). Scorpioninae can be separated from Opistophthalminae by means of the following characters: pedipalps orthobothriotaxic, with 26 trichobothria (including 13 trichobothria in e series of patella); cheliceral coxae without stridulatory setae (scaphotrix) on prodorsal surfaces and chemoreceptive lamelliform setae (trichocopae) on promedian surfaces.

INCLUDED TAXA: As redefined in the present contribution, Scorpioninae comprises a single genus, Scorpio Linnaeus, 1758 , with 17 species and at least four subspecies ( Fet, 2000; Kovařík, 2009; Lourenço, 2009; Lourenço and Cloudsley- Thompson, 2009, 2012; Lourenço et al., 2012; Talal et al., 2015; Lourenço and Rossi, 2016).

DISTRIBUTION: Africa: Algeria, Benin, Cameroon, Chad, Egypt (including Sinai), Eritrea, Ethiopia, Libya, Mauritania, Morocco, Niger, Senegal, Sudan, Tunisia. Asia: Iraq, Iran, Israel and the Palestinian territories, Jordan, Kuwait, Lebanon, Qatar, Saudi Arabia, Syria, Turkey, Yemen.

The broad distribution of Scorpio extends across the Sahel from Senegal, Niger and Benin in West Africa, through northern Cameroon, to Sudan and northern Ethiopia, and from Morocco, along the Mediterranean to Egypt, the northern part of the Arabian Peninsula, and the Middle East as far north as southern Turkey and as far east as central Iran. Although the full extent of the distributional range has yet to be accurately mapped, it appears to be discontinuous, as evidenced by the occurrence of isolated populations in the Hoggar, Tassili n’Ajjer and Ennedi mountain ranges of the Sahara ( Vachon, 1952a; Kanter, 1971; Lourenço et al., 2012; Lourenço and Rossi, 2016). This disjunction is interpreted as relictual and attributed to range contraction associated with the onset of aridification in northern Africa ( Niethammer, 1971; Dumont, 1982).

As noted by Prendini et al. (2003), the distributions of the species of Scorpio conform to the typical pattern of localized endemics exhibited among species of the other African scorpionid genera, suggesting that similar mechanisms of speciation have operated in all. The only differ- ence is that the species of Scorpio have not diverged to the same extent as the species of the other genera, which may reflect the relatively recent onset of aridification in northern Africa in the late Miocene–early Pliocene (<8 Ma; Axelrod and Raven, 1978; Van Zinderen Bakker, 1978, 1980; Pickford and Senut, 2000). Less time for morphological divergence may explain why the species of Scorpio are more similar morphologically than the species of Opistophthalminae and Pandininae .

Scorpio has not been recorded from Burkina Faso, the Gambia, Mali, or Mauritania but may occur in some or all of those countries. Vachon (1950) rejected Pallary’s (1938) record from the central Congo, but Levy and Amitai (1980) suggested that the genus could occur there. As with records from Tanzania (e.g., Lamoral and Reynders, 1975; Fet, 2000), this record is probably attributable to a misidentification. Scorpio does not occur in India as suggested by some authors ( Birula, 1925; Levy and Amitai, 1980).

ECOLOGY: All subspecies of Scorpio appear to be obligate burrowers, constructing burrows under stones and/or in open ground by means of their chelicerae, short, robust legs with stout, spiniform macrosetae distributed laterally and distally on the basitarsi, curved telotarsal ungues, and thickened metasoma. In contrast with Opistophthalmus , no species of Scorpio exhibits psammophilous or lithophilous adaptations, although different species exhibit specific substratum preferences. High densities of burrows occur in suitable habitat but, unlike some Heterometrinae and Pandininae , cohabitation of multiple individuals within a single burrow (except during courtship or parental care) and/or the communal construction of burrows are absent ( Levy and Amitai, 1980; Shachak and Brand, 1983).

Although ecological data are unavailable for most species, S. fuscus (Ehrenberg, 1829) and S. palmatus (Ehrenberg, 1828) , occurring parapatrically in Israel, have been extensively studied ( Levy and Amitai, 1980; Shachak and Brand, 1983; Kotzman et al., 1989; Danin, 1994; Rutin, 1996; Talal et al., 2015), while ecological studies on S. kruglovi Birula, 1910 (as S. maurus fuscus ) have also been conducted in neighbouring Jordan and Turkey ( Amr and El-Oran, 1994; Crucitti, 1999). These species differ markedly in their substratum requirements, S. fuscus preferring harder soils, e.g., terra rossa, basalt, and rendzina, than S. palmatus , which inhabits brown-red sandy soils, loess and alluvium ( Levy and Amitai, 1980). They also differ in their burrow structure. The burrows of S. palmatus are always constructed in open ground and run parallel to the ground surface for approximately 10 cm, before turning downward for 20–70 cm and ending in an enlarged chamber. The burrows of S. fuscus are often constructed under stones and usually run vertically, without turns, to a depth of approximately 40 cm, where they end in an enlarged chamber. Mesosomal percussion, involving rapid drumming of the posterior sternites against the ground, has been observed in males of both species ( Rosin and Shulov, 1961).

CONSERVATION STATUS: Perhaps due to smaller size and more specialized ecological requirements (necessitating more elaborate methods for successful captive husbandry), Scorpio appears to be less popular in the exotic pet trade and thus more seldom offered. Nonetheless, at least one species, S. palmatus (imported from Egypt), is available almost year-round in Europe, the United States, and Japan ( Hull-Williams, 1986; Mahsberg et al., 1999; Rubio, 2000). Another, S. fuscus (imported from Israel) is rarely available. Similar life history parameters to Heterometrus , Opistophthalmus , and Pandinus , including long gestation period (14–15 mo.), small brood sizes (8–25), age to sexual maturity (3–4 yr) and parental care ( Birula, 1917b; Levy and Amitai, 1980; Shachak and Brand, 1983; Polis and Lourenço, 1986; Crucitti, 1999), together with restricted distributional ranges, render species of Scorpio vulnerable to overharvesting. Fortunately, the reduced demand for Scorpio in the pet trade, together with their occurrence in many countries from which exportation of wildlife is strictly prohibited and in arid to semiarid habitats that are less vulnerable to destruction than the rainforests inhabited by many species of Heterometrinae and Pandininae , suggests that they are somewhat less vulnerable.

REMARKS: Rossi (2016a) created two new tribes of Scorpioninae , in addition to the nominotypical tribe: Opistophthalmini accommodated Opistophthalmus and Protophthalmini accommodated Protophthalmus , revalidated from synonymy with Opistophthalmus . As noted above, the evidence overwhelmingly suggests that Scorpioninae , as defined by Rossi (2016a), is paraphyletic, justifying the removal of Opistophthalmini and its elevation to the rank of subfamily, thereby restricting the nominotypical subfamily Scorpioninae to the genus Scorpio .

Although Scorpio originally accommodated several species (e.g., Simon, 1872a; Pocock, 1900b), only a single, widespread species, S. maurus Linnaeus, 1758 , with 19 official subspecies ( Fet, 2000), was recognized by 1910, a status quo that persisted for almost a century. Scorpio remained monotypic on the grounds that no reliable characters could distinguish its subspecies and circumstantial evidence of hybridization between two subspecies occurring in the eastern Mediterranean region ( Vachon, 1950; Levy and Amitai, 1980). The fact that the subspecies of S. maurus could be diagnosed on the basis of somatic characters presented in several keys ( Birula, 1910; Vachon, 1950, 1952a; Levy and Amitai, 1980), however, prompted the suggestion that most if not all should be recognized as phylogenetic species ( Prendini et al., 2003; Froufe et al., 2008), a move partially implemented without rigorous reanalysis of the variation by Lourenço (2009). Analyses of multilocus DNA sequence data, morphology and burrowing behavior among two putative subspecies from the eastern Mediterranean region ( Talal et al., 2015) confirmed earlier suggestions that S. maurus is a species complex, rather than a single widespread polymorphic species, with many subspecies, as portrayed by earlier literature. A thorough systematic revision of Scorpio , applying modern concepts and techniques, including a phylogenetic analysis based on morphological and molecular data for a comprehensive taxon sample, remains to be presented, however.