Mesobuthus Vachon, 1950

Kovařík, František, 2019, Taxonomic reassessment of the genera Lychas, Mesobuthus, and Olivierus, with descriptions of four new genera (Scorpiones: Buthidae), Euscorpius 288, pp. 1-27 : 17-20

Genus Mesobuthus Vachon, 1950

( Figures 134–137, 148, 161–163, 171–172)

Mesobuthus (in part) Vachon, 1950: 152–152 (1952: 324– 325); Fet & Lowe, 2000: 169–181 (complete references list until 2000).

TYPE SPECIES. Androctonus eupeus C. L. Koch, 1839 .

DIAGNOSIS. Medium-sized buthids, adults 35–60 mm. Sternum type 1 (Soleglad & Fet, 2003), various degrees of an irregular pentagon in shape. Pedipalps orthobothriotaxic, type Aβ ( Vachon, 1974, 1975), femur trichobothrium d 2 dorsal, patella d 3 dorsal of dorsomedian carina. Chelal trichobothrium db usually located between est and esb, or may be on level with trichobothrium est. Trichobothrium eb clearly on fixed finger of pedipalp. Pectines with fulcra. Dentate margin of pedipalp-chela movable finger with distinct denticles divided into 11–12 linear rows and 5 terminal denticles. Chelicerae with typical buthid dentition (Vachon, 1963, figs. 32–33), fixed finger armed with two denticles on ventral surface. Tergites I–VI granular, with three carinae, tergite VII with 5 carinae. Carapace with distinct carinae, entire dorsal surface nearly flat. First sternite with two granulated lateral stridulatory areas, which however may be reduced in some species. Metasoma elongate, segment I with 10 carinae, segments II-III with 8–10 carinae, segment IV with 8 carinae. Ventrolateral carinae of metasomal segment V posteriorly usually with several large lobated denticles. Telson elongated or bulbous, bumpy and granulated, without subaculear tooth. Legs III and IV with well developed tibial spurs. No sexual dimorphism in shape of metasoma.

SUBORDINATE TAXA (12 SPECIES). Mesobuthus afghanus (Pocock, 1889) , stat. n. ( Afghanistan,

Iran, Turkmenistan) Mesobuthus agnetis (Werner, 1936) ( Iran) Mesobuthus bogdoensis (Birula, 1896) , stat. n. ( Kazakhstan,

Russia) Mesobuthus eupeus (C. L. Koch, 1839) ( Armenia, Azerbaijan,

Georgia, Iraq, Iran, Syria, Turkey) = Androctonus ornatus Nordmann, 1840 = Buthus cognatus L. Koch, 1878 = Buthus eupeus philippovitschi Birula, 1905 Mesobuthus haarlovi Vachon, 1959 , stat. n. ( Afghanistan) Mesobuthus iranus (Birula, 1917) , stat. n. ( Iraq, Iran) Mesobuthus macmahoni ( Pocock, 1900) ( Iran, Pakistan) Mesobuthus mongolicus (Birula, 1912) , stat. n. ( China,

Mongolia) Mesobuthus persicus (Pocock, 1899) , stat. n. ( Iran) =? Buthus eupeus kirmanensis Birula, 1900 = Buthus pachysoma Birula, 1900 Mesobuthus phillipsii (Pocock, 1889) ( Iran, Iraq, Syria,

Turkey) = Buthus eupaeus mesopotamicus Penther, 1912 Mesobuthus thersites (C. L. Koch, 1839) , stat. n. (? China, Iran, Kazakhstan, Kyrgyzstan, Russia, Tajikistan, Turkmenistan, Uzbekistan)

=? Buthus eupeus barszczewskii Birula, 1904

Mesobuthus vesiculatus (Pocock, 1899) ( Iran)

COMMENTS. Gantenbein et al. (2003, 2005) published the first DNA-based phylogeny for Mesobuthus , which revealed three complexes of species inside the genus (see also Fet et al., 2018). However, without a detail comparison with other buthid genera it still appeared that the Mesobuthus is a monophyletic genus. Only a detailed comparison with related genera (a revision in preparation by our research group) demonstrated that these three complexes constitute three separate genera, of which Mesobuthus sensu stricto and Olivierus are very close sister taxa, while Aegaeobuthus gen. n. is more closely related to the genus Compsobuthus than to both Mesobuthus and Olivierus . For morphological differences among these three genera we can use the characters used in Fet et al. (2018: 54) and other major characters cited here. While genus Olivierus was recently revised (as “ Mesobuthus caucasicus complex”; Fet et al., 2018), both other genera, mainly Mesobuthus sensu stricto, require a detailed revision.

Most species of the genus Mesobuthus were traditionally considered the subspecies of Mesobuthus eupeus . Mirshamsi et al. (2011: 15) elevated Mesobuthus phillipsii to the species level based on DNA analysis. Other subspecies are elevated here to the species level according to morphological characters presently studied for a detailed genus-level revision (in preparation by our research group). In my opinion, subspecies rank is not supported in this genus (as in most scorpion genera when subspecies have been revised), and all described Mesobuthus taxa are either species or synonyms.

AFFINITIES. KovařÍk (2009) used nine characters, which in combination differentiate Mesobuthus sensu lato from all other buthids: pedipalps orthobothriotaxic, type Aβ (alfa - configuration); legs III and IV with well developed tibial spurs; cheliceral fixed finger with two denticles on ventral surface; trichobothrium eb located on fixed finger of chela; tergites I– VI with 3 carinae; dentate margin of pedipalp-chela movable finger with distinct denticles divided into 11–14 linear rows and 5 terminal denticles; tarsomeres of legs with paired ventral spines or setae; carinae of carapace forming a lyre-shaped configuration; ventrolateral carinae on metasoma V with irregular denticles .

The main trait that differentiates the genus Aegaeobuthus gen. n. from both Olivierus and Mesobuthus is the presence of sexual dimorphism. The males of Aegaeobuthus gen. n. have longer and narrower metasomal segments than females, with a rather elongate telson ( Figs. 164–168) while in Olivierus and Mesobuthus there is no sexual dimorphism in the shape of metasomal segments ( Figs. 168–172). The second major difference is presence of ventrolateral carinae on metasoma IV in Aegaeobuthus gen. n. ( Figs. 164–168) and their absence in Olivierus and Mesobuthus ( Figs. 169– 172).

Aegaeobuthus gen. n. includes more similar species, which are hard to differentiate morphologically from each other since several characters which help to differentiate species within other genera exhibit only intraspecific variability here. I can mention the number of denticle rows on movable finger, which were, for example, used by Ythier (2018) as the main character to support a new species he described from Crete (validity of which should be further confirmed). In reality, within Aegaeobuthus gen. n. there is variability from 11 to 14 rows of these denticles even within a population (see Figs. 150–151). On the contrary, this character can help to distinguish Olivierus from Mesobuthus . Genera Olivierus and Mesobuthus are more similar to each other, and validity of Olivierus was repeatedly discussed in the past ( Gantenbein et al., 2003). Olivierus includes rather larger species, adults of 49–90 mm in size, while the genus Mesobuthus includes adults of 35–60 mm in size.