Rhynchelmis (Rhynchelmis) limosella Hoffmeister, 1843

Fend, Steven V. & Brinkhurst, Ralph O., 2010, Contributions towards a review of the genus Rhynchelmis Hoffmeister (Clitellata: Lumbriculidae), Zootaxa 2407, pp. 1-27 : 7-10

Rhynchelmis (Rhynchelmis) limosella Hoffmeister, 1843

( Fig. 3 )

Supplementary description. Body wall annulations very strong; secondary annulations begin in III. Clitellum VIII–XXVIII. Pharynx extends to V or VI, about equally developed ventrally as dorsally. Starting in about IX, thick diagonal muscles originating in the circular muscle layer extend from the lateral line to near middorsal; by about XV they form diagonal sheets extending through most of segment. Longitudinal muscle bands narrowed and curled inwards at the edges ( Fig. 3 K).

Anterior segments with a single pair of lateral blood vessels in posterior part of segment. The posterior lateral vessel pair joins the ventral vessel at least through XXXIII. An anterior lateral vessel pair usually present from near XX and posteriorly, joining the perivisceral sinus. Posterior pair of lateral blood vessels in posterior segments with branches extending to body wall. First nephridia in XIII; tubules extend dorsally (along posterior lateral vessels) and ventrally; nephropores anterior to ventral chaetae.

Spermatheca similar to that of R. tetratheca . Ampulla ovate, with narrower, anterior diverticulum ( Figs. 3 I–J); sperm may line up in diverticulum. Spermathecal ampullae connect to gut via very short ducts ( Fig. 3 K). Single accessory organ in IX similar in structure to atrium: lining cells cuboidal, muscle layer 6–8 Μm thick, covered with petiolate clusters of granular, prostate-like cells ( Fig. 3 H). Ectal duct runs beneath the nerve cord to an inconspicuous papilla. Accessory organ appears absent in worm labeled “ R. limosella f. occidentalis ”.

Posterior male funnels larger than the anterior, folded back into XI, but vas deferens does not penetrate septum 10/11 ( Figs. 3 A–B). Vasa deferentia 50–110 m in diameter, with thick, glandular epithelium ( Fig. 3 C); both vasa join atrium subapically ( Fig. 3 D). Prostates begin in X ( Fig. 3 A); cells granular, in densely-packed, petiolate bundles connected to atrial epithelium via thin ducts ( Figs. 3 C–D). Atrial muscle tube 50–70 Μm in diameter; epithelium ciliated, with cuboidal cells; muscle layer about 3–6 Μm thick ( Figs. 3 C–D, 3G). Male pore on small papilla within a shallow sac, surrounded by cluster of accessory glands similar to prostates ( Figs. 3 E–F).

Rhynchelmis (Rhynchelmis) vagensis Hrab ĕ, 1961 ( Fig. 4 )

Supplementary description. Pharynx about equally thick dorsally and ventrally. Longitudinal sheets of oblique, dorsolateral muscles strongly developed. No preclitellar nephridia; nephridia with dorsal loop following posterior lateral blood vessel ( Fig. 4 A). Nephridial duct expanded, forming a vesicle at pore ( Fig. 4 B). One lateral blood vessel pair joins ventral vessel near posterior septum of each segment. Lateral blood vessel branched in posterior segments of whole mount, relatively few branches in middle segments of sectioned worm.

Accessory organ with petiolate, prostate-like glands ( Fig. 4 D). Atria and vasa deferentia extend only to XIII. Prostates begin near ectal end of atrium. Anterior male funnels smaller than posterior. Male pore with petiolate accessory glands, but otherwise simple; as described for other R. ( Rhynchelmis ) species ( Fig. 4 C).

Rhynchelmis (Rhynchelmis) vejdovskyi Hrab ĕ & Č ernosvitov, 1926 ( Fig. 5 )

Supplementary description. Body usually tetragonal in transverse section, with distinct longitudinal ridges associated with muscle bands ( Fig. 5 A). Dorsolateral oblique muscles prominent, they join dorsal margin somewhat lateral to the midline, leaving a small dorsomedian longitudinal muscle band. Longitudinal muscle bands strongly curled inwards at the edges ( Fig. 5 A). Clitellum IX–XVI. Pharynx begins dorsally in I, ventrally in II, ending near 4/5; about equally developed ventrally as dorsally ( Fig. 5 B). Small, glandular masses occur on either side of ventral nerve cord in anterior segments, but do not appear to have ectal ducts. No preclitellar nephridia. Nephridia with postseptal expansion followed by tubule loop to near dorsal vessel ( Figs. 5 C–D). Ectal duct thickened at end ( Fig. 5 D), or with large, distinct vesicle ( Fig. 5 C); contents may be darkly-staining.

Spermathecae with a narrow, anterior diverticulum from the ampulla; sperm concentrated in diverticulum ( Fig. 5 E). Ampulla globular, ental end connects to gut; ectal duct long and thin; ectal pore on ventral chaetal line, midway between chaetae and septum 8/9.

Posterior vas deferens does not loop into XI. Anterior male funnel smaller than posterior, without sperm ( Figs. 5 F–G). Both vasa deferentia join atrium apically ( Fig. 5 H). Atria may be convoluted, ending in XI but reach to XII when straight; irregularly tubular, diameter 56–70 μm; length to about 800 μm ( Fig. 5 G). Vasa deferentia with thick, glandular epithelium, diameter 34–46 μm, slightly thinner than atria ( Fig. 5 I). Atrial musculature thin, epithelial cells indistinct; multicellular prostate glands densely cover atrium to near male pore ( Fig. 5 G). Penes are very inconspicuous papillae at most; clusters of petiolate accessory glands at male pores ( Fig. 5 J).

Figures

FIGURE 3. R. limosella from Hrabė collection. (A) segments IX – XII, showing atrium, male funnels, and accessory organ. (B) male funnels and vasa deferentia at ectal end of atrium. (C) atrium and vas deferens. (D) ental end of atrium, with vasa deferentia embedded under the muscle layer. (E – F) male pore. (G) atrium and vas deferens. (H) accessory organ. (I – J) spermatheca and diverticulum. (K) spermathecal ampullae at gut. (A – B, F – J sagittal sections, C – E, K transverse sections). Scale bars: C, D, F – H = 100 μm; A, B, E, I – K = 200 μm.

FIGURE 4. R. vagensis from Hrabė collection. (A) nephridium. (B) nephridial pore. (C) male pore. (D) accessory organ. (All from sagittal sections). Scale bars = 100 μm.

FIGURE 5. R. vejdovskyi. (A) curled longitudinal muscles and oblique muscles in a post-clitellar segment. (B) head and pharynx. (C) nephridial vesicle and funnel. (D) nephridial duct extending vertically from pore. (E) part of spermathecal duct, ampulla and diverticulum. (F) atrium and male funnels in IX – X. (G) atrium, funnels, and vestigial septal sac in X – XII. (H) ental end of atrium with approaching vas deferens. (I) atrium and vas deferens. (J) male pore. (A transverse section, B – K sagittal sections). Scale bars: A – G, J = 200 μm; H, I = 100 μm.