Orchibdella peruviensis

External morphology

A robust species of moderate size, approximately 60 mm in total length. Gonopores separated by 1/2 + 5 annuli, with the male gonopore located in XI b6 and the female in XII/XIII. Eyes situated in the usual position: 5 pairs—specifically in annuli 2, 3, 4, 5, and 7—corresponding to somites II, III, IV, V (a1+a2), and VI (a1+a2). Somites I, II, III, and IV are uniannulate; V and VI are biannulate; VII is triannulate; VIII is quadriannulate, with the first annulus subdivided; IX through XXV are complete (or quinquannulate); XXVI is triannulate; and XXVII is uniannulate. The anus is located at XXV/XXVI.

Internal morphology

The oral chamber lacks a velum; the pharynx is narrow, extending as far as XII/XIII, and features 12 longitudinal muscular ridges that are faintly discernible throughout the entire length of the pharynx; the mid-intestine possesses ceca. Two pairs of testes are present in each interganglionic interval, extending from the posterior half of XIV to the anterior half of XXIII, totaling 17 pairs. The unpaired male genitalia are micromorphic and megalomorphic; the paired ducts—the spermatic and ejaculatory ducts—develop along the recurrent (descending) course of the spermiducts. Unpaired female genitalia are absent. The vasa deferentia ascend as far as XI, then follow a long descending course; the epididymides are coiled within the recurrent portion of the spermiducts, situated in somites XIII and XIV, or at the same level within XIII. Each continues into a thick ejaculatory duct, folded in a U-shape and lacking a bulb, which enters at the same level as its counterpart—at the beginning of the prostatic region of the atrium—or alternatively, both enter asymmetrically, with one entering at the beginning and the other at the distal end of this prostatic region. The atrium consists of a long penile sac, terminating caudally in a globose prostatic region that extends as far as segment XIV, at the level of the first pair of testes. The ovaries are convoluted and tubular, located in segments XIV and XV; each continues into its respective oviduct, and these join above the female orifice, with no discernible vagina or bursa.

Habitat & range

Habitat

Freshwater

Region

South America

Recorded from

Peru

Original description

Ringuelet, Un curioso hirudineo alto andino del Peru (Orchlbdella peruviensis nov.sp., Hirudiniformes Cyclobclellidae). (1976). Limnobios, 1(4), 101-104

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