Helobdella dubia

External morphology

Body narrow and stout, with simple, undivided rings lacking tubercles or papillae, exhibiting the facies characteristic of species within the *Gloiobdella michaelseni* group. Total length-to-maximum width ratio: greater than 3. Acetabulum (sucker) small and subterminal. Two eyes located in somite IV. Gonopores separated by a single ring; the male gonopore is situated in XII a2, and the female in XII a2/a3. The mouth is displaced toward the base of the anterior lip of the hood, positioned at the level of somite II or between II and III. Anus located at the XXVI/XXVII intersegmental furrow. Somites I and II are fused, or separated by only a faint furrow at I/II; III and IV are uniannulate (single-ringed), though both exhibit incipient subdivision; V is biannulate; VI through XXIV are triannulate; XXV is biannulate; and XXVI and XXVII are uniannulate. Coloration is violet-gray or yellowish, with a creamy-white ventral surface, featuring a distinct line and a broader band situated on either side of the dorsal midline.

Internal morphology

The pharynx is thick and follows a recurrent or ascending course—that is, it terminates in a hook-like curve; the salivary glands are semicompact, arranged in two distinct clusters. There are seven postgenital pairs of small diverticula (ceca) within the crop; the third, fourth, and fifth pairs appear merely as simple sacculations. The seventh pair of post-ceca, located in somite XIX, follows a brief descending course. There are six pairs of testes. The vasa deferentia follow a recurrent or descending path; the transition in diameter from the vas deferens to the ejaculatory duct is gradual. The ejaculatory ducts form a long pre-atrial loop, extending as far back as the XVII/XVIII intersegmental furrow.

Habitat & range

Habitat

Freshwater

Region

South America

Recorded from

Argentina

Junior synonyms

Batracobdella dubia