Review of cavernicolous scorpions in the Balkans

 

Cavernicolous scorpions are fascinating with their choice of habitat and in some cases morphological adaptions. This group of scorpions are usually divided into four categories: Accidentals, trogloxenes, troglophiles, and troglobites. The categories are explained in the introduction of the article mentioned below. It is the two latter categories that have caves as their main habitats, but not all of the scorpions in these groups have troglomorphic traits (e.g. reduced eyes, reduced pigmentation etc.). They who do are true troglobites.

Javier Blasco-Aróstegui and Lorenzo Prendini have recently published a review of cavernicolous scorpions in the Balkans. They have classified the known cavernicolous species into the categories mention above, presented a redescription of the only real troglobitic species, Euscorpius studentium Karaman, 2020, and provided a identification key for the to the identification of cavernicolous scorpions occurring in the Dinaric Karst area.

Abstract:
Cavernicolous scorpions are difficult to collect and study due to their often inaccessible habitats. Some have evolved unique morphological adaptations, known as troglomorphies, including reduced sclerotization and pigmentation, reduction and/or loss of eyes, attenuation and elongation of the appendages, which assist them to thrive in dark, humid and low-energy input environments. Cavernicolous scorpions are classified into accidentals, trogloxenes, troglophiles, and troglobites. The Balkans, and particularly the Dinaric Karst region, host a diverse cave-adapted fauna, including scorpions. Despite an 1895 report of a blind scorpion from Bosnia and Herzegovina, the first truly troglobitic European scorpion, Euscorpius studentium Karaman, 2020, was only described a few years ago, based on two immature specimens. In the present contribution, this unique species is redescribed based on the first adult specimens; the ecological classification of all currently known cavernicolous Euscorpiidae Laurie, 1896, is updated; a key to the identification of cavernicolous scorpions occurring in the Dinaric Karst is provided; and the historical and geographical factors affecting the distribution and conservation of cavernicolous scorpions in the Balkans is reviewed.

Reference:
Blasco-Aróstegui J, Prendini L. Redescription of Euscorpius studentium Based on Adult Specimens; Updated Classification of Cavernicolous Euscorpiidae; and Review of Cavernicolous Scorpions in the Balkans. Diversity. 2024;16(12):737. [Open Access]

Thanks to Gerard Dupre and Siegfried Huber for informing me about this article!

A large revision of parts of the genus Euscorpius with two new genera

The genus Euscorpius Thorell, 1876 (Euscorpiidae) has turned out two be very complex with many cryptic and hidden taxa that has only been revealed after genetical analysis. A large number of new species have been described in the last decade.

Less attention have been on the complex Alpiscorpius complex containing the old taxa Euscorpius germanus C. L. Koch, 1837 and E. mingrelicus Kessler, 1874. Frantisek Kovarik and co-workers have now published a major study investigating this species complex in Italy, Austria and Slovenia. The study has resulted in the following taxonomical changes:

Alpiscorpius Gantenbein et al., 1999 is raised from subgenus status. The following species are included in this genus (New comb. = Transfered from genus Euscorpius):

A. alpha (Caporiaco, 1950). New comb.

A. beroni (Fet, 2000). New comb.

A. beta (Di Caporiacco, 1950). New status. Previously part of E. alpha.

A. delta Kovarik, Stundlova, Fet & Stahlavsky, 2019. New species from Italy.

A. gamma (Caporiaco, 1950). New comb.

A. germanus (C.L. Koch, 1837). New comb.

A. kappa Kovarik, Stundlova, Fet & Stahlavsky, 2019. New species from Slovenia.

A. lambda Kovarik, Stundlova, Fet & Stahlavsky, 2019. New species from Slovenia and Italy (?).

A. mingrelicus (Kessler, 1874). New comb.

A. omega Kovarik, Stundlova, Fet & Stahlavsky, 2019. New species from Slovenia.

A. omikron Kovarik, Stundlova, Fet & Stahlavsky, 2019. New species from Slovenia.

A. phrygius (Bonacina, 1980). New comb.

A. sigma Kovarik, Stundlova, Fet & Stahlavsky, 2019. New species from Italy and Slovenia.

A. uludagensis (Lacroix, 1995). New comb.

A. ypsilon Kovarik, Stundlova, Fet & Stahlavsky, 2019. New species from Austria and Slovenia.

The authors inform that the populations of Euscorpius (Alpiscorpius) spp. in the major part of the Balkan Peninsula remain unrevised. This means that there may be further changes in the future.

Tetratrichobothrius Birula, 1917 is raised from subspecies status and the genus' only species is Tetratrichobothrius flavicaudis (DeGeer, 1778), which is transfered from Euscorpius.

The article has a identification key for the new genus Alpiscorpius.

Abstract:
Two subgenera of Euscorpius Thorell, 1876 (Scorpiones: Euscorpiidae) are elevated to the genus status: Alpiscorpius Gantenbein et al., 1999, stat. n. and Tetratrichobothrius Birula, 1917, stat. n. Seven new Alpine scorpion species are described and illustrated: Alpiscorpius delta sp. n. (Italy) from the “alpha group” (“germanus complex”); A. kappa sp. n. (Slovenia) and A. lambda sp. n. (Slovenia) from the “germanus group” (“germanus complex”); A. omega sp. n. (Slovenia), A. omikron sp. n. (Slovenia), A. sigma sp. n. (Italy, Slovenia), and A. ypsilon sp. n. (Austria, Slovenia) from the “gamma group” (“mingrelicus complex”). The taxonomic validity of these cryptic species is confirmed through cytogenetic and DNA analysis (Štundlová et al., 2019). Alpiscorpius beta (Di Caporiacco, 1950), comb. n., stat. n. (Italy, Switzerland) is restored from synonymy and elevated to species level within the “alpha group”. Euscorpius germanus marcuzzii Valle et al., 1971 (Italy), recently elevated to species level, is synonymized with Alpiscorpius germanus (C. L. Koch, 1837), comb. n. (which is found in Austria, Italy, and Switzerland but not in Slovenia). The genus Alpiscorpius currently includes 15 valid species (6 in “germanus complex” and 9 in “mingrelicus complex”). Many populations of Alpiscorpius spp. from the Balkan Peninsula, formerly listed under Euscorpius gamma or E. mingrelicus, remain unassigned.

Reference:
Kovarik F, Stundlova J, Fet V, Stahlavsky F. Seven new Alpine species of the genus Alpiscorpius Gantenbein et al., 1999, stat. n. (Scorpiones: Euscorpiidae). Euscorpius. 2019(287):1-19. [Open Access]

Family Euscorpiidae

Cytogenetic and molecular approaches reveal cryptic diversity in Alpine scorpions in the genus Euscorpius

Phenotypic conservatism is typical for many scorpion taxa.In layman's term, this mean that many scorpion species look morphologically similar making it almost impossible to separate them by traditional taxonomical methods. The European genus Euscorpius Thorell, 1876 (Euscorpiidae) is an excellent example of this. Originally this genus contained less than then species, while today it contains no less than 64 species.

And it seems that there is still more to come. By using a new combination of cytogenetic and molecular methods, Jana Štundlováa and co-workers have recently published a study of the three Alpine species of the subgenus Euscorpius (Alpiscorpius): E. (A.) alpha, E. (A.) germanus, and E. (A.) gamma.

Their study reveals a cryptic diversity in the populations of the Alpine species, with several "races" (highly distinct karyotypic races) within each species. These races had discrete geographical distributions. Even though these results clearly shows several independent taxa, a thorough taxonomical revision with morphological studies of the subgenus is necessary before any taxonomical decisions can be made.

Some of the methods used in this study are new and open new possibilities for our understanding of the species diversity of scorpions.

Abstract:
Over time, mountain biota has undergone complex evolutionary histories that have left imprints on its genomic arrangement, geographical distribution and diversity of contemporary lineages. Knowledge on these biogeographical aspects still lags behind for invertebrates inhabiting the Alpine region. In the present study, we examined three scorpion species of the subgenus Euscorpius (Alpiscorpius) from the European Alps using cytogenetic and molecular phylogenetic approaches to determine the variation and population structure of extant lineages at both chromosome and genetic level, and to provide an insight into the species diversification histories. We detected considerable intraspecific variability in chromosome complements and localization of the 18S rDNA loci in all studied species. Such chromosome differences were noticeable as the existence of three [in E. (A.) alpha and E. (A.) germanus] or four [in E. (A.) gamma] range-restricted karyotypic races. These races differed from one another either by 2n [in E. (A.) alpha 2n=54, 60, 90; in E. (A.) gamma 2n=58, 60, 88, 86–92], or by the karyotypic formula [in E. (A.) germanus 2n=34m+12sm; 36m+10sm; 42m+4sm]. Using mitochondrial (16S rRNA, COI) and nuclear (28S rDNA) genetic markers, we examined genetic variation and reconstructed phylogenetic relationships among the karyotypic races. Both approaches provided evidence for the existence of ten deeply divergent lineages exhibiting the features of local endemics and indicating the presence of cryptic species. Molecular dating analyses suggest that these lineages diversified during the Plio-Pleistocene and this process was presumably accompanied by dynamic structural changes in the genome organization.

Reference:
Stundlova J, Smid J, Nguyen P, Stahlavsky F. Cryptic diversity and dynamic chromosome evolution in Alpine scorpions (Euscorpiidae: Euscorpius). Mol Phylogenet Evol. 2019;134:152-63. [Subscription required for full text]

Thanks to Victor Fet and Frantisek Kovarik for sending me this interesting article!

New Euscorpius discovered

Gioele Tropea has looked into Euscorpius tergestinus (C. L. Koch, 1837) (Euscorpiidae) and discovered that this widespread, polymorphic species actually is two distinct species. Populations previously named Euscorpius carpathicus aquilejensis (C. L. Koch, 1837) (which has been in synonymy with E. tergestinus (C. L. Koch, 1837)), are now given species status. The new species' name is Euscorpius aquilejensis (C. L. Koch, 1837).

Euscorpius aquilejensis (C. L. Koch, 1837): Restricted to northern and central Italy, San Marino, Vatican City State, western Slovenia, northwestern Croatia.

Euscorpius tergestinus (C. L. Koch, 1837): Restricted to Italy (extreme northeast), Slovenia, Croatia, Austria (introduced) and Czech Republic (introduced)

Both morphological and genetic data confirm the validity of the two species.

Abstract:
After the revision of Fet & Soleglad (2002), Euscorpius tergestinus (C. L. Koch, 1837) was considered a polymorphic species widespread from France to Croatia. In this study, we reconsidered the taxonomy of E. tergestinus s.str. based on morphological and genetic evidence, its range, and its original description. Euscorpius aquilejensis (C. L. Koch, 1837), stat. nov., previously synonymous with E. tergestinus, is elevated to species status herein. A preliminary phylogenetic analysis based on available GenBank 16S rDNA data shows a separate, basal position of E. aquilejensis and some other Euscorpius species, which implies that the subgenus Euscorpius s.str. is paraphyletic.

Reference:
Tropea G. Reconsideration of the taxonomy of Euscorpius tergestinus (Scorpiones: Euscorpiidae). Euscorpius. 2013 (162):1-23. [Free full text]

Family Euscorpiidae 

Thanks to Gioele Tropea for sending me his new article!