Eremidrilus pinedai, Rodriguez & Fend, 2022

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 : 253-254

3.3. Eremidrilus pinedai n. sp.

( Figs. 2B,E ; 3F–I ; 5 )

Holotype. USNM 1593356 , whole worm, slide-mounted in Canada balsam.

Type locality. California, Del Norte Co., Smith River below forks, N 41.8729, W 124.1243, 40 m altitude (25 May 2002), S. V. Fend coll.

Paratypes. USNM 1593357-1593360 , from the type locality, 25 May 2002, 2 whole-mounted, 1 dissected, 1 transversely sectioned. CASIZ 233662 , from the type locality, 25 May 2002, 1 whole-mounted; CASIZ 233663 from the type locality, 8 June 2003, 1 dissected on slide. MNCN 16.03 /3149, from type locality, 25 May 2002, 1 whole-mounted, stained in borax carmine and mounted in Kleermount, and MNCN 16.03 /3150 sagittally sectioned. S. V. Fend coll.

Etymology. Named after the naturalist Antonio Pineda, born in Guatemala, and head of the naturalist team on the Malaspina expedition (1789–1794) ( Madulid 1982), for his contributions to the knowledge of the Nearctic fauna.

Other material. From the type locality: 12 May 2001, 3 whole-mounted. 25 May 2002, 3 whole-mounted, 1 dissected, 3 sectioned (1 sagittal, 2 transverse). 8 Jun 2003, 1 whole-mounted, 1 dissected ( Table 1 ). S. V. Fend coll.

Description. Segments 60–98. Length of fixed worms 15–27 mm, body diameter in X 0.34–0.50 mm. Proboscis 418−675 µm long, about 70 µm diameter at middle ( Fig. 2B ). Segmentation distinct in anterior segments; secondary annulus from IV to IX. All chaetae simple-pointed and sigmoid; in anterior body segments 113−155 µm long, shorter in II (ca. 65−75 µm), with nodulus slightly distal (about 0.4 chaeta length from the tip); in ventral bundles chaetae usually a little longer than dorsals of the same segment (median length of dorsals: 130 µm; ventrals: 134 µm) ( Fig. 2E ). Chaetae in mid-body 108−167 µm long, only slightly shorter in posterior segments, and nodulus distal (0.3–0.4 from tip). Male pores on the line of ventral chaetae, on low and often indistinct porophores (18–32 µm high, 40–85 µm wide) located in the posterior part of segment X ( Figs. 2B ; 3G, I ; 5C, D ). Spermathecal pores inconspicuous, opening in the ovarian segment, slightly lateral to ventral chaetae, and at about 2/3 of the distance from ventral chaetae bundle to posterior septum ( Figs. 2B ; 3H, I ; 5F ). Female pores in 11/12, on line of ventral chaetae.

Epidermis in anterior segments 6–10 µm thick. Body diameter greatest in clitellar segments, but clitellum weakly developed in most mated specimens (8–10 µm thick); up to 16 µm thick in a few specimens, with small glandular cells aligned in transverse rows ( Fig. 5A ). Longitudinal muscles to about 25 µm thick. Pharynx with a well-developed dorsal pad. Pharyngeal glands in (IV)V−VI(VII). Nephridia typical for the genus, composed of a short anteseptal funnel and tubular postseptal ducts that can extend through several segments dorsally and posteriorly; the ectal ducts about 10 µm diameter, without a terminal vesicle.

Sperm sacs usually extend anteriorly to VIII, posteriorly to XV; egg sacs to XVI. Vasa deferentia 14−24 µm wide and about 300−420 µm long, posterior about as long as anterior. Posterior vasa form a loop in XI, and both vasa join the atrial muscle layer near mid-atrium, entering the atrial lumen subapically. Atria entirely in X (148–244 µm long), club-shaped ( Figs. 3G, I ; 5C ), length about half the body diameter, muscle layer 2−4 µm thick, lining cells 6−12 µm high, and atrial ampulla densely covered by prostate glands (12–26 µm high), with densely-packed, often indistinct clusters ( Figs. 3G, I ; 5B, E ). Maximum atrium diameter 37–50 µm, narrowing towards male pore to about 20 µm just before the porophore. The ectal end of atrial duct may project slightly, forming a small papilla on the porophore ( Figs. 2B ; 3G ; 5C, D ).

One pair of spermathecae opens in XI, and ampullae may extend into XII. Spermathecal ampullae ovate, 1.3 times longer than wide, about 5 times the length of the duct, and containing spermatozoids loosely clustered or forming a ring, but not oriented towards the epithelium ( Fig. 5F ). Spermathecal ducts short and tapered (42–85 µm long, 32–48 µm maximum diameter, narrowing to about 20–30 at pore), length less than one fifth the body diameter, with muscle layer thin, and lining cells columnar ( Figs. 3H, I ; 5F ).

Remarks. As in other California species, E. pinedai n. sp. has only one pair of spermathecae, in the ovarian segment, but it is well distinguished by a combination of characters. As in E. chalonensis n. sp. (described above), the spermathecal duct is very short, i.e. the ratio of the spermathecal duct length to the body diameter in E. pinedai is 0.1–0.2; the spermathecal pore opens near the line of ventral chaetae, but it is not associated with conspicuous glands. The short spermathecal ducts and the ventral position of the spermathecal pores are reminiscent of the Eremidrilus species with two pairs of spermathecae (see Fend & Rodriguez 2020), but E. pinedai n. sp. is also distinguished by the small atria with short porophores. The atrium is short relative to the diameter of the body in X, as in E. humboldti and E. ritocsi . However, E. pinedai n. sp. has more weakly defined male porophores (cf. E. humboldti : Figs. 3A–E ; 4A , in Fend & Rodriguez 2020; E. ritocsi : Figs. 5C 6E in Fend & Rodriguez 2003). In addition, E. humboldti has two spermathecal segments, and the spermathecal pores of E. ritocsi are midlateral. The male porophore of E. pinedai is smaller and usually less prominent than in most of the other Eremidrilus species having a single pair of spermathecae (cf. Figs. 9 and 12 in Fend & Rodriguez 2003) ( Table 2 ). The sperm organization within the spermathecae may also distinguish E. pinedai from E. ritocsi , in which sperm is arrayed in a characteristic spiral pattern (Fig. 11 in Fend & Rodriguez 2003). Dark detritus and a variety of diatoms were seen in the gut ( Fig. 5G ).

The Smith River is an isolated, mid-sized (ca. 200,000 ha) drainage entering the Pacific Ocean in northwestern California. It is a large, alluvial stream without dams; discharge is highly variable, but flow is permanent ( National Water Information System, 2022). Much of the drainage is protected by the National Wild and Scenic Rivers Act (2022) and the river has large runs of several native salmonids ( Hogan & Zuber 2012). In addition to E. pinedai , the apparently endemic lumbriculid Kincaidiana smithi Fend & Rodriguez, 2017 ( Fend et al. 2017) was described from a nearby site. E. pinedai n. sp. was collected by digging into gravel/cobble sediments at the edge of a large gravel bar.

Figures

FIGURE 2. Eremidrilus n. spp. Drawings of whole mounted anterior ends, and representative chaetae pairs (left: dorsal, right: ventral) in middle segments of the 3 new species. A, D. E. chalonensis. B, E. E. pinedai. C, F. E. owyhee. (A–D, drawn from type specimens.)

FIGURE 3. Eremidrilus n. spp. Drawings of the reproductive system for the 3 new species (all from type specimens). A–E. E. chalonensis, F–I. E. pinedai, J–M. E. owyhee. A, I, J: Reproductive organs in X–XI. B, G, L: View of atria and male pores in X, reconstructed from transverse sections. C, H, M: Spermathecae in XI, reconstructed from transverse sections. D: Ventrolateral view of E. chalonensis spermatheca, showing glands and muscular ring around pore. E: E. chalonensis nephridium, showing vesicle at nephridiopore. F: Detail of E. pinedai spermatheca, lateral view. K: Detail of E. owyhee male porophore and atrium, reconstructed from transverse sections.Arrows show the position of chaetal bundles (All scales are 100 µm.)

FIGURE 4. Eremidrilus chalonensis n. sp. All from type specimens. A. Anterior body section-bearing proboscis. B. Clitellum in XI. C, D. Atrium (complete in C) and male pore in prominent porophore. E, F. Spermatheca and glands around spermathecal pore. G. Spermathecal pore viewed from ventral surface. H. Nephridial vesicle in a whole-mount specimen (2 photos combined). I. Diatoms in the gut of the worms. (A, B, G, H, whole mounts; C–F, I, histological sections. All scales are 50 µm.)

FIGURE 5. Eremidrilus pinedai n. sp. A. Clitellum. B, C. Atrium. D. Transverse section showing the male pore at the porophore. E. Atrium and sperm funnel. F. Spermatheca and female funnel. G. A variety of diatoms in the digestive track of the worms. (A, C, whole mount of paratype; B, D–F histological sections of paratypes; G, whole mounts from individuals in type locality. All scales are 50 µm.)

FIGURE 6. Eremidrilus owyhee n. sp. All from type collection, except for Fig. 6A. A. Anterior part of the body. B. Male porophore. C. Atrium (composed of 2 photos). D. Ectal part of the spermatheca. E. Spermathecal ampulla showing spermatozoids, some with head oriented toward epithelium. F. Transverse section of the spermatheca pore opening within a lateral body fold, showing muscular fibers at retracted pore. G. Transverse body fold below the lateral line, containing the spermathecal pore (2 photos). H. Nephridium. (A, B, G, H, whole mounts; C–F histological sections. All scales are 50 µm, except for A: 500 µm.)