Eremidrilus Fend & Rodriguez, 2003

Rodriguez, Pilar & Fend, Steven V., 2022, New Nearctic Eremidrilus species (Clitellata: Lumbriculidae). Part 2, western species with one spermathecal segment, Zootaxa 5159 (2), pp. 245-264 : 263-264

Genus Eremidrilus Fend & Rodriguez, 2003

Diagnosis (from Fend & Rodriguez 2020): Small or medium-sized worms with a filiform proboscis. Body wall unpigmented and bearing secondary annuli. Posterior lateral blood vessels absent. Nephridia absent from preclitellar segments. Testes paired in both IX and X. One pair of ovaries in XI. One pair of elongate-cylindrical or club-shaped atria in X, each with one pair of functional vasa deferentia, serving funnels on 9/10 and 10/11. Male pores usually on broad, folded porophores posterior to ventral chaetae in X, on or slightly lateral to chaetal lines. Spermathecae paired in XI or in both XI and XII. Spermathecal pores posterior to chaetae, with transverse position ranging from ventral chaetal lines to lateral lines.

Key to described Eremidrilus species

1 One pair of spermathecae only, in XI ( Fig. 7 in present publication)............................................. 2

- Two pairs of spermathecae, in XI and XII (Fig. 11 in Fend & Rodriguez 2020).................................... 8

2 Spermathecal pores midlateral or distinctly lateral to ventral bundles of chaetae................................... 3

- Spermathecal pores in line with or slightly lateral to ventral bundles of chaetae.................................... 5

3 Spermathecal pores each in a deep cavity, associated with extensive musculature; may be everted to form a porophore. Male and spermathecal porophores more than 100 µm in diameter. Atrium club-shaped, length usually 2–3 times the porophore width, 2/3 body diameter. (Pacific Coastal drainages, Central California to southern Oregon.).................................................................................................. E. felini Fend & Rodriguez, 2003

- Spermathecal pores simple, not on porophores, in a shallow depression at most, at level of lateral line.................. 4

4 Atrium club-shaped, about 4 times longer than wide, and the length 2–3 times the porophore width; male porophore low and rounded (length <diameter). (Coast Range, central California.)..................... E. ritocsi Fend & Rodriguez, 2003

- Atrium cylindrical with very narrow diameter, about 8 times longer than wide, and the length 6 times the porophore width. Male pores open in long, protrusible porophores, narrowly conical when fully extended. (Northern Nevada to southwestern Idaho.)...................................................................................... E. owyhee n. sp.

5 Spermathecal pores surrounded by a ring of small glands, spermathecal duct short (0.1–0.2 body diameter) and ampulla elongate.Atrium length about half body diameter, male pores on dome-shaped porophores. Nephridia with prominent ectal vesicles. (Chalone Creek, central California.)..................................................... E. chalonensis n. sp.

- Spermathecal pores not surrounded by glands.............................................................. 6

6 Spermathecal duct length about twice the diameter of the ampulla, or about equal to the body diameter, usually penetrating the posterior septum 11/12. Atria cylindrical, 4–8 times the male porophore width, length usually more than 2/3 the diameter of the body. (Coast Range, central California.)....................................... E. elegans Fend & Rodriguez, 2003

- Spermathecal duct shorter than the diameter of the ampulla, about 1/4 to 1/2 the diameter of the body, gradually narrowing towards the pore. Atria club-shaped and located entirely in X.................................................. 7

7 Body diameter at X 0.6–0.9 mm. Spermathecal pores slightly lateral to the ventral chaetal line, at most 1/2 the distance to the lateral line. Spermathecal duct to body diameter ratio: 0.2–0.5. Atrium length 4–6 times the porophore width; porophore large (width 60–100 µm). (Coyote Creek, Coast Range, central California.)................ E. coyote Fend & Rodriguez, 2003

- Body diameter at X 0.3–0.5 mm. Spermathecal pores close to the line of ventral chaetae. Spermathecal ducts short (ratio to body diameter 0.1–0.2). Atrium length 5–7 times the porophore width. Porophore small (24–45 µm wide). (Smith River, northern California.)............................................................................. E. pinedai n. sp.

8 Male pore opening on a small papilla, porophores inconspicuous or absent. Spermathecal pores close to posterior septum of the segment. (Eureka Creek, Montana)...................................... E. montanensis Fend & Rodriguez, 2020

- Male pores opening on distinct porophores................................................................. 9

9 Male pore opening on a small, conical papilla within a ring shaped, concave male porophore. Spermathecal pores very posterior in the segment. Atrium very long (2/3 the body diameter or more) and wide in ental part (ampulla diameter about 1/3 atrium length), with thick (up to 42 µm) atrial muscular layer, duct narrow and clearly distinct from the ampulla. (Idaho.)................................................................................ E. artzaini Fend & Rodriguez, 2020

- Atrium club-shaped, duct not clearly distinct from ampulla; atrial musculature <10 µm............................ 10

10 Atrium long (about the diameter of the body or even longer). Spermathecal pores mid-way between ventral bundles of chaetae and septum. (Tennessee, cave.)................................................. E. allegheniensis (Cook, 1971)

- Atrium short (about half the diameter of body or less). At least the second pair of spermathecal pores in the segment XII, close to septum 12/13..................................................................................... 11

11 Broad male porophore, atrium length about 1/3 body diameter. Vasa deferentia open subapically to the atrial lumen. (Malad River drainage, Idaho.)................................................. E. humboldti Fend & Rodriguez, 2020

- Narrow, cylindrical male porophore. Atrium length about 1/2 body diameter. Vasa deferentia open to the atrial lumen about medially. (Gila River drainage, New Mexico.).................................... E. gilita Fend & Rodriguez, 2020

Figures

FIGURE 7. Comparative schematic drawings of the reproductive segments in the Eremidrilus species having one pair of spermathecae. Dashed line represents the lateral line; arrows indicate diagnostic characters.