Complex male genitalia (hemispermatophores) are not diagnostic for cryptic species in the genus Euscorpius (Scorpiones: Euscorpiidae)

Genital morphology is often used as a key character for distinguishing species in many arthropod groups. Regarding scorpions, male genitalia (hemispermatophores) have been increasingly used in species descriptions. In the present study we analyse hemispermatophores of four Central European species of Euscorpius Thorell, 1876, and those of Euscorpius flavicaudis (De Geer, 1778) from southern France. The main focus are the three morphologically cryptic species, Euscorpius alpha Caporiacco, 1950, Euscorpius germanus (C.L. Koch, 1837), and Euscorpius gamma Caporiacco, 1950. The clear, deep split between E. alpha and E. germanus previously shown from nuclear allozyme data and mitochondrial genetic markers is not found in hemispermatophore and other morphological characters. Even the hemispermatophore of E. gamma—a species branching off at the same genetic distance level as E. alpha and E. germanus, and clearly diagnosable on external morphological characters—is indistinguishable from those of E. alpha and E. germanus. Although hemispermatophores are complex, they are not more informative than other morphological characters. Euscorpius hemispermatophores may be useful for species discrimination, but in closely related species they are of limited taxonomic value. r 2004 Elsevier GmbH. All rights reserved.