Descrição morfológica de duas novas espécies de oligoquetas (Annelida: Crassiclitellata) da Reserva Biológica do Gurupi – Maranhão, Brasil

Abstract

Soil is one of the main reservoirs of terrestrial biodiversity, harboring organisms that are essential to the functioning of ecosystems. Among them, oligochaetes (earthworms) stand out, playing a fundamental role in soil formation. The objective of this study was to morphologically describe two new species of oligochaetes, Cryptodrilus sofiae sp. nov. and Andiorrhinus jamesi sp. nov., collected in the Gurupi Biological Reserve in Maranhão. Through morphological and histological analyses, it was possible to characterize and describe Cryptodrilus sofiae sp. nov. based on its calciferous glands with fjord-like patterns and Andiorrhinus jamesi sp. nov. based on its lamellar calciferous glands. The species exhibited restricted distribution and low natural abundance, with Cryptodrilus sofiae sp. nov. found exclusively in old-growth forests, demonstrating greater dependence on conserved habitats; in contrast, Andiorrhinus jamesi sp. nov. was found in areas undergoing post-fire regeneration, suggesting a certain resilience when forest structure and soil integrity are partially preserved. The description of Andiorrhinus jamesi sp. nov. reinforces the diversity of the subgenus Turedrilus in Brazil, while the proposal of Cryptodrilus gen. nov. highlights the evolutionary complexity of the group and the need for refined histological techniques for precise taxonomic distinction. In short, this study expands our taxonomic knowledge of earthworms and underscores the importance of conserving the Gurupi Biological Reserve.