Pandininae Thorell, 1876

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 : 438-442

Subfamily Pandininae Thorell, 1876

Pandinini Thorell, 1876a: 11 (subfamily, part), type genus: Pandinus Thorell, 1876 ; 1876b: 84 (subfamily, part); Karsch, 1879a: 19 (subfamily, part); Thorell and Lindström, 1885: 25 (subfamily, part); Rossi, 2016a: 19, 20, 22, 26, 27.

Pandininae : Rossi, 2016a: 19, 20, 22, 26.

Pandinopsini Rossi, 2016a: 19, 20, 24, 26; syn. nov.

DIAGNOSIS: Pandininae are the sister group of Heterometrinae ( Prendini, 2000a; Prendini et al., 2003). Both subfamilies share the following characters, by means of which they can be separated from Opistophthalminae and Scorpioninae : presence 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; similar counts of pro- and retroventral spiniform macrosetae on telotarsi I and II and III and IV. Pandininae can be separated from Heterometrinae by means of the following characters: pedipalps neobothriotaxic major, with more than 26 trichobothria (patella with more than 13 trichobothria in e series and more than 3 trichobothria in v series; chela usually with more than 4 trichobothria in V series and often with more than 2 trichobothria in i series); granular tubercles of “rasp” and stridulatory setae (scaphotrix) of “scraper” situated on coxae of pedipalp and first leg, respectively. Pandininae can be further separated from Opistophthalminae by means of the following characters: cheliceral coxae without stridulatory setae (scaphotrix) on prodorsal surfaces and chemoreceptive lamelli- form setae (trichocopae) on promedian surfaces. Pandininae can be further separated from Scorpioninae by means of the following characters: digital carina of pedipalp chela obsolete; pedipalps neobothriotaxic major, with more than 26 trichobothria.

INCLUDED TAXA: As redefined in the present contribution, Pandininae includes 44 species in seven genera ( Prendini, 2001a, 2016; Kovařík et al., 2016, 2017b, 2017c, 2019b): Pandiborellius Rossi, 2015 ; Pandinoides Fet, 1997 ; Pandinops Birula, 1913 ; Pandinopsis Vachon, 1974 , stat. nov.; Pandipalpus Rossi, 2015 , stat. nov.; Pandinurus Fet, 1997 ; Pandinus Thorell, 1876 .

DISTRIBUTION: Africa: Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Congo, Côte d’Ivoire, Democratic Republic of Congo, Djibouti, Equatorial Guinea (including Bioko Island), Eritrea (including Disei Island), Ethiopia, Gabon, the Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Malawi, Mali, Mozambique, Nigeria, Niger, Senegal, Sierra Leone, Somalia, Sudan, Tanzania, Togo, Uganda, Zambia. Asia: Saudi Arabia, Yemen.

Pandininae are distributed from the tropical rainforest and mesic savanna of western and central Africa to the arid savanna and semidesert of eastern Africa and the southwestern Arabian Peninsula. Species of Pandininae have not been recorded from Burundi or Rwanda but may also occur in those countries.

Several authors ( Lamoral and Reynders, 1975; Fet, 2000) cited the presence of Pandipalpus viatoris ( Pocock, 1890) (as Pandinus viatoris ) in Zimbabwe, apparently based on Hirst’s (1911) records from Petauke and Broken Hill [Kabwe]. Hewitt (1918: 152) also mentioned these records but noted that P. viatoris “is not known to the Rhodesian Museum from South Rhodesia [ Zimbabwe].” Prendini et al. (2003: 234) discussed the putative records of P. viatoris from Zimbabwe, demonstrated that these records occur in Zambia (formerly Northern Rhodesia), and noted that there are no credible records of Pandinus south of the Zambezi River. Kovařík (2012: 19, fig. 64) did not cite Prendini et al. (2003) and erroneously plotted three points for P. viatoris south of the Zambezi River, one in the extreme north of Zimbabwe (presumably, the specimen erroneously labelled “ Mashonaland ” [ZMB 35310]) and two in Mozambique, corresponding to the approximate locations of Tete and Beira, where this species does not appear to occur based on surveys by the first author. Rossi (2015a: 20, 21, 29) discussed the reliability of Kovařík’s (2012) Zimbabwean record, but apparently missed the point about the Zambezi River, as he did not mention the other two localities, and went on to describe Pandinurus (P.) prendinii Rossi, 2015 , from a single female, allegedly from Messina in the Limpopo Province of South Africa. Prendini (2016: 57) synonymized P. prendinii with Pandinurus (P.) sudanicus ( Hirst, 1911) on the grounds that the meristic data listed as diagnostic for P. prendinii fall entirely within the ranges given for P. sudanicus . Additionally, Prendini (2016) noted that the suggestion that P. prendinii may represent a relictual population of Pandininae in southern Africa, and that, because the putative type locality is 5000 km from the known localities of P. sudanicus , this could justify its recognition as distinct from the latter, rests entirely on the grossly mistaken assumption that the locality data are trustworthy, an assumption doubted by others ( Kovařík, 1997). Despite extensive surveys of scorpions throughout southern Africa by the first author, there are no credible records of Pandininae from south of the Limpopo River, let alone south of the Zambezi River ( Prendini et al., 2003; Prendini, 2005, 2016).

ECOLOGY: Pandininae includes some of the largest extant scorpions, e.g., Pandinopsis dictator ( Pocock, 1888) and Pandinus imperator (C.L. Koch, 1841) , which can reach 170–200 mm in length ( Vachon, 1952b; Newlands, 1987; Sissom, 1990). The ecology, behaviour and ecophysiology of P. imperator have been extensively studied (e.g., Toye, 1970; Garnier and Stockmann, 1973; Casper, 1985; Mahsberg, 1990). Burrows are preferentially constructed in termitaria and under stones or logs, and may contain up to 20 individuals, with the largest nearest the entrance ( Toye, 1970; Polis and Lourenço, 1986; Mahsberg, 1990). Mixed age groups of related and unrelated individuals cohabit with minimal aggression or cannibalism in laboratory terraria, and group living has been demonstrated to contribute significantly to postembryonic growth rate and survival probability, especially among kin ( Mahsberg, 1990; Kriesch, 1994). Pandinus imperator (C.L. Koch, 1841) is known for its unusual activity rhythms. Diurnal activity has frequently been observed in this species, which may appear on the surface in large numbers, especially after rains ( Toye, 1970; Newlands, 1987).

Ecological data are unavailable for many species of Pandininae . However, the thickened metasoma, short, robust legs with stout, spiniform macrosetae distributed retrolaterally and distally on the basitarsi, and curved telotarsal ungues of most species are consistent with the fossorial, pelophilous ecomorphotype ( Prendini, 2001b), as in Pandinoides , Pandinops , Pandipalpus , and, to a lesser extent, Pandinopsis and Pandinus ( Newlands, 1987; Prendini et al., 2003; Kovařík, 2016; Prendini, 2016; personal obs.).

Pandinoides and Pandipalpus viatoris construct very deep burrows (up to 1 m) in hard, compacted clayey to sandy-clay soils using the chelicerae, first two pairs of legs, and metasoma. Burrow entrances are situated in open ground, often at the base of small bushes or shrubs. Burrows may be single entrance, occupied by a single individual, or composite and multientrance, containing multiple related individuals of overlapping generations which cohabit with minimal aggression or cannibalism ( Newlands, 1987; Prendini, 2016; personal obs.). Burrows of the smaller Pandinops , usually constructed in sandy or clayey loam are usually shallower (40–50 cm deep), spiralling, and always with a single entrance and occupied by a single individual (Kovařík, 2016; L. Prendini, personal obs.). Some species of Pandinops approach the semipsammophilous ecomorphotype observed among some Opistophthalminae , with the macrosetae on the basitarsi usually longer and more numerous than in Pandinoides and Pandipalpus .

Unlike Pandinoides , Pandinops , and Pandipalpus , species of Pandiborellius and Pandinurus appear to be lapidicolous, corticolous, or semilithophilous ( Prendini, 2001b). Species of both genera for which data are available, e.g., Pandiborellius awashensis ( Kovařík, 2012) , Pandiborellius insularis Kovařík et al., 2017 , Pandiborellius magrettii (Borelli, 1901) , Pandiborellius nistriae (Rossi, 2014) , Pandinurus afar Kovařík et al., 2017 , Pandinurus citernii (Borelli, 1919) , Pandinurus platycheles (Werner, 1916) , and Pandinurus trailini ( Kovařík, 2013) , construct shallow burrows or scrapes under large stones ( Kovařík, 2011, 2013; L. Prendini, personal obs.). Some species of Pandinurus , e.g., Pandinurus exitialis ( Pocock, 1888) , Pandinurus fulvipes Kovařík et al., 2019 , Pandinurus gregoryi (Pocock, 1896) , P. trailini , Pandinurus phillipsii (Pocock, 1896) , and Pandinurus smithi ( Pocock, 1899) , also inhabit the cracks and crevices of rock outcrops, spaces under the peeling bark of fallen or standing trees, or the holes of tree trunks, up to 2 m above ground ( Kovařík, 2011, 2013; Kovařík et al., 2019b; L. Prendini, personal obs.). Some of these species, especially Pandinurus , are partially dorsoventrally compressed, and exhibit elongation of the legs, reduction of the retrolateral row of spiniform macrosetae on the leg tibia, strongly curved ungues and, in some species, an enlarged, curved pseudonychium (dactyl) on the telotarsi. Similar characters occur in some Heterometrinae (notably Heterometrus and some Chersonesometrus and Deccanometrus ) as well as arboreal chactids and hormurids, and are regarded as semilithophilous, corticolous and lapidicolous adaptations ( Prendini 2001b).

CONSERVATION STATUS: Pandinus imperator (the “Emperor scorpion”), three species of Pandinoides (the “Red-claw scorpion”), i.e., Pandinoides cavimanus ( Pocock, 1888) , Pandinoides duffmackayi Prendini, 2016 , Pandinoides militaris (Pocock, 1900) , and, to a lesser extent, Pandipalpus viatoris , are readily available in Europe, the United States, and Japan for the international trade in exotic pets. Most of these appear to originate from Ghana, Côte d’Ivoire, and Togo ( P. imperator ) and Tanzania ( P. cavimanus and P. duffmackayi ). Pandiborellius awashensis and Pandinops hawkeri (Pocock, 1900) , from Ethiopia, have occasionally been offered for sale in the United States, and Pandinus ugandaensis Kovařík, 2011 , from Uganda, has been offered in Germany ( Prendini et al., 2003; L. Prendini, personal obs.). Dupré (1992) records the importation of P. dictator into France from Cameroon and that of P. militaris (as P. cavimanus ) from Kenya. Pandinus imperator is the most common species of scorpion in the exotic pet trade, for which an extensive literature on captive husbandry and breeding exists (e.g., Larrouy et al., 1973; Garnier, 1974; Hull-Williams, 1986; Krapf, 1988; Copeland, 1990; Dupré, 1990; Montambaux, 1996; Schiejok, 1997; Mahsberg et al., 1999; Rubio, 2000).

As with Heterometrinae , wild populations of Pandininae are vulnerable to overharvesting for the exotic pet trade due to their long gestation period (at least 7 mo.), small brood sizes (30– 35), and longevity (4–7 yr to sexual maturity) ( Vachon et al., 1970; Larrouy et al., 1973; Polis and Lourenço, 1986; Mahsberg, 1990; Polis and Sissom, 1990). Furthermore, wild populations are threatened not only by overexploitation but by continuing destruction of their habitat through deforestation and agriculture.

The decline in P. imperator may be partially alleviated by its CITES status (IUCN 1994; Lourenço and Cloudsley-Thompson, 1996), which has led to the issuing of export quotas in several West African countries (e.g., Benin, Chad, Niger, and Togo), and the ease with which this species may be bred in captivity. However, it is unclear whether the CITES status has had any real impact in protecting the remaining wild populations, because wild-caught specimens continue to be advertised alongside captive-bred specimens by major dealers. Moreover, although two other closely related species, P. dictator and P. gambiensis , were also provided CITES status, these are seldom available in the pet trade whereas others that are (especially species of Pandinoides ) have no CITES status. The conservation status of most species of Pandininae is presently unknown, but the restricted ranges of most are cause for concern. Species of Pandinoides , in particular, should be CITES listed ( Prendini, 2016).

REMARKS: Extensive work on the systematics of the taxa presently assigned to Pandininae was conducted by several authors during the past two decades ( Kovařík, 2000, 2003, 2009, 2011, 2012, 2013, 2016, 2017; Prendini, 2000b, 2004, 2016; Prendini et al., 2003; Lourenço, 2014; Rossi, 2014 a, 2014b, 2014c, 2014d, 2015 a, 2015b, 2015c, 2016 a, 2016b; Kovařík et al., 2017b, 2017c, 2019b). A history and critique of the taxonomy of the group, summarizing all developments to that point and providing several amendments to the classification, was presented by Prendini (2016). Rossi (2016 a, 2016b) meanwhile presented another revised classification, followed by an attempted rebuttal of Prendini’s (2016) critique. Kovařík et al. (2017b) followed with yet another revised classification and critique of Rossi’s (2016a) classification. Whereas Rossi (2016a) recognized seven genera and six subgenera (three nominotypical), arranged into three tribes (one nominotypical) of subfamily Pandininae, Kovařík et al. (2017b) recognized five genera and three subgenera (one nominotypical), without tribes, in subfamily Scorpioninae , following the long-discredited classification of Soleglad and Fet (2003a), according to which Diplocentridae and Urodacidae are treated as subfamilies of Scorpionidae despite overwhelming evidence dating back three decades ( Stockwell, 1989; Prendini, 2000a) that Scorpionidae , so construed, is a paraphyletic assemblage. Aside from disagreements in the suprageneric ranks, the primary differences between the classifications of Pandininae by Rossi (2016a) and Kovařík et al. (2017b) boil down to the recognition of three genera, Pandicaporiaccous Rossi, 2015, Pandinopsis and Pandipalpus , and three subgenera, Pandinurus (Pandipavesius) Rossi, 2015 , and Pandinus (Pandinoriens) Rossi, 2015 , and Pandinoides (Dunlopandinoides) Rossi, 2016 , by Rossi (2016a) but not by Kovařík et al. (2017b).

Prendini (2016) previously synonymized Pandinurus (Pandicaporiaccous) Rossi, 2015 , with Pandinurus (Pandiborellius) Rossi, 2015 , and both Rossi (2016a) and Kovařík et al. (2017b) elevated Pandiborellius to the rank of genus, hence Pandinurus (Pandicaporiaccous) Rossi, 2015 = Pandiborellius Rossi, 2015 , syn. nov. Additionally, Kovařík et al. (2017b) synonymized Pandinurus (Pandipavesius) with Pandiborellius and Pandinus (Pandinoriens) Rossi, 2015 , with Pandinurus , decisions that appear well justified. Kovařík et al. (2017b) did not address Pandinoides (Dunlopandinoides) , but it is evident from both the diagnosis and examination of the type material (2 ♂, ZMB 15009) that this subgenus, justified solely on the slightly shallower concavity in the male pedipalp chela manus in its type species, cannot be upheld. Accordingly, Pandinoides (Dunlopandinoides) Rossi, 2016 = Pandinoides Fet, 2000 , syn. nov.

The decision by Kovařík et al. (2017b) to recognize Pandinopsis and Pandipalpus as subgenera of Pandinus in the face of evidence to the contrary is unjustifiable, however; their recognition as subgenera of Pandinus became untenable with the removal and elevation to the equivalent rank of genus of other former subgenera, i.e., Pandinoides , Pandinops , and Pandinurus . The inclusion of P. dictator and the two species of Pandipalpus within Pandinus renders the latter paraphyletic, as demonstrated in phylogenetic analyses based on morphology and multilocus DNA sequence data, which recovered P. viatoris monophyletic with P. cavimanus to the exclusion of P. imperator , and P. imperator monophyletic with P. cavimanus and P. viatoris to the exclusion of P. dictator ( Prendini, 2000a; Prendini et al., 2003; unpublished data). In order to restore the monophyly of Pandinus , these taxa are hereby elevated to the rank of genus, Pandinopsis Vachon, 1974 , stat. nov., and Pandipalpus Rossi, 2015 , stat. nov., resulting in two new combinations: Pandinopsis dictator ( Pocock, 1888) , comb. nov., and Pandipalpus viatoris ( Pocock, 1890) , comb. nov. Any other course would obviously require all currently recognized genera of Pandininae to be relegated to subgenera of Pandinus , as originally proposed by Vachon (1974), with some adjustments.

Unpublished data, indicating that Pandipalpus , Pandinoides , and Pandinops form a monophyletic group, to the exclusion of other genera of Pandininae , imply that Pandinini, as defined by Rossi (2016a), is also paraphyletic, justifying the following synonymy: Pandinopsini Rossi, 2016 = Pandininae Thorell, 1876 , syn. nov. It is also evident, based firstly on the absence of consistent morphological differences, and secondly on low genetic divergence between samples collected at the type locality of Pandinus lowei Kovařík, 2012 , and across the distribution of P. viatoris (unpublished data), that these taxa are conspecific, justifying the following synonymy: Pandinus lowei Kovařík, 2012 = Pandipalpus viatoris ( Pocock, 1890) , syn. nov. Consequently, Pandinurus (Pandipalpus) pygmaeus Rossi, 2015 = Pandipalpus viatoris ( Pocock, 1890) , syn. nov., as originally proposed by Prendini (2016). The same is true for two Ethiopian species of Pandinurus , described from the same type locality, which are synonymized accordingly: Pandinus intermedius Borelli, 1919 = Pandinurus citernii (Borelli, 1919) , syn. nov.