The coevolution between telson morphology and venom glands in scorpions (Arachnida)

As in previous contributions to the JVATiTD, the aim of this note is to bring some general information on a particular aspect of the scorpion biology. An attempt is made to explain the possible coevolution of telson morphology and venom glands, which took place during several hundred million years and in particular since scorpions migrated from aquatic to terrestrial environments. Three components can be directly associated with predation and defensive behaviours: (1) morphology of the chelae and structure of the chelae fingers granulations; (2) morphology of the metasoma and in particular of the telson; (3) evolution of tegumentary glands in the telson toward different types of venom glands. Since a number of recent contributions already treated some of these aspects, I will limit my comments to the possible evolution of the telson in relation to the evolution of venom glands. As in previous contributions, the content of this article is basically addressed to non-specialists on scorpions whose research embraces scorpions in several fields such as venom toxins and public health.(AU)

Fine structural analysis of the stinger in venom apparatus of the scorpion Euscorpius mingrelicus (Scorpiones: Euscorpiidae)

In this study, the morphology, histology and fine structure of the stinger, a part of the venom apparatus of Euscorpius mingrelicus (Kessler, 1874) (Scorpiones: Euscorpiidae) were studied by light microscopy and transmission electron microscopy (TEM). The stinger, located at the end section of the telson, is sickle-shaped. The venom is ejected through a pair of venom pores on its subterminal portion. Both venom ducts extend along the stinger without contact with each other since they are separated by connective tissue cells. The stinger cuticle is composed of two layers. Additionally, there are many pore canals and some hemolymph vessels in the cuticle. This work constitutes the first histological and fine structure study on Euscorpius mingrelicus stinger.(AU)

The venom gland of the scorpion species Euscorpius mingrelicus (Scorpiones: Euscorpiidae): morphological and ultrastructural characterization

The histology and ultrastructure of venom glands in the scorpion Euscorpius mingrelicus (Kessler, 1874) are described and illustrated in the current study for the first time by employing light microscopy and transmission electron microscopy (TEM). The venom apparatus is composed of a pair of venom glands and a stinger, both situated in the last segment of the metasoma. The venom glands are completely separate but similar. The two glands are segregated within the telson by striated muscle bundles, and their outer surfaces are surrounded by a cuticle. An internal layer constitutes the secretory epithelium. This epithelium is made up of simple columnar cells. The nucleus and organelles involved in cellular synthetic activity are situated basally. In the apical portion, near the gland lumen, there are many secretory granules of different sizes, shapes and electron densities.(AU)

Study of the relationship between Androctonus crassicauda (Oliver, 1807; scorpiones, buthidae) venom toxicity and telson size, weight and storing condition

Scorpions are included in the order Scorpiones; class Arachnida. Lethal scorpions are mostly of the Buthidae family. Among these, species belonging to Androctonus, Leiurus and Mesobuthus genera cause most scorpion envenomations in Turkey. This study was performed aiming the production of antivenom by using Androctonus crassicauda telsons. Venom toxicity is related to telson weight, size, and storing condition (open or closed). Telsons of A. crassicauda were collected in Southeastern Anatolia (especially in Harran town, Sanliurfa), Turkey. They were separated according to weight, size, and storing condition - open (a) and closed (b). Venom solution was prepared by maceration of telsons. Swiss albino mice were used to determine the lethal dose 50% (LD50), which was as follows: Group 1a - 2.31mg; Group 1b - 2.66mg; Group 2a - 2.32mg; Group 2b - 2.66mg; Group 3a - 6.66mg; Group 3b - 6.88mg. Among the groups of telsons, the first and the second groups showed different characteristics. However, there were no differences between their toxicity. In the third group, a fourfold amount of telsons was used for toxicity. In other words, telsons weighting from 19.99 to 20mg (first group) and from 29.99 to 30mg (second group) presented similar LD50 values, and telsons weighting from 10 to 19.99mg (third group) showed a fourfold higher LD50 value. This difference was caused by the maturity of scorpions and venom toxicity was related to their size. The first and second groups were considered to be mature and the third group, not adult. Therefore, we can conclude that obtaining open telsons due to environmental factors was not effective for venom toxicity.