Troglodrilus (Annelida, Oligochaeta, Tubificidae), a New Genus from Subterranean Habitats in Southwestern Europe

Abstract

Over the last 20 years, several specimens of the tubificid oligochaete Tubificoides galarzai Giani & Rodriguez, 1988 were collected from subterranean waters of the North-West Iberian Peninsula (cave Mairulegorreta, Spain), the East Hexagon (subterranean gallery of Montgelas near Lyon (département du Rhône, France), and Crotot Cave in the vicinity of Romain (located northeast of Besançon, département du Doubs, France). Subsequent study of specimens from these various sites – and in particular, their genitalia and setal morphology – provided us with the opportunity to measure the variability of characters in specimens from each site, and subsequently assess the intraspecific geographical variation in this species. Examination of serial histological sections of male ducts of French specimens now supports a revaluation of the taxonomic status of T. galarzai. The new material confirms that the vas deferens enters the atrium apically, not opposite to the prostate junction (as stated in the original description), thus justifying its exclusion from the genus Tubificoides. Although a clear histological separation is not observable in the proximal end of the atrium, two kinds of cells are present in the atrial epithelium near the entrance of prostate gland – similar to the histological structure described in Lamadrilus sorosi Timm 1998. The relationship of T. galarzai with several species of the genus Tubifex is also discussed. A new genus Troglodrilus n. gen. is proposed for this tubificine oligochaete that seems to be restricted to subterranean waters.