Anatomia comparada do esqueleto endofragmal na família de caranguejos de água doce trichodactylidae (crustacea: brachyura)

Abstract

In brachyuran crustaceans the endophragmal skeleton is the main support structure of the locomotory complex. Its origin is cuticular and it is formed by the sternite and pleurite plates of the eight thoracic somites and their internal invaginations. The ventral characters of the endophragmal skeleton, reflected externally in the suture lines of the thoracic sternum, are a important classification criteria for the current suprageneric system of Trichodactylidae: [Trichodactylinae & Dilocarcininae (Dilocarcinini + Valdiviini)]. In order to test this hypothesis, the internal and external characters of the endophragmal skeleton of 42 adult crabs belonging to 17 species and 10 genera were examined. For the preparation of the material, the crabs were dissected and their skeletons submerged in a hot solution of potassium hydroxide (KOH) for a period of 24 to 48 hours. The analysis of the skeletons was performed with the aid of a stereomicroscope, and drawings of the most relevant structures were digitally inked using Adobe Illustrator CS2(R) based on digital photographs. Variations in the shape, orientation and level of interruption of the thoracic sternum, pleural roof, ventral and dorsal phragmas and junction plates were described from anatomical preparations. Based on these characteristics, the species were separated into three groups, which is consistent with the proposed classification of Trichodactylidae into subfamilies and tribes. This study highlights the importance of the morphological characteristics of the endophragmal skeleton for Trichodactylidae taxonomy.