Eremidrilus allegheniensis ( Cook, 1971 )

Fend, Steven & Rodriguez, Pilar, 2020, New Eremidrilus species (Clitellata: Lumbriculidae) from western North America Part 1, species with two spermathecal segments, Zootaxa 4809 (1), pp. 111-131 : 124

Eremidrilus allegheniensis ( Cook, 1971)

( Figures 9 , 10 , 11A )

Trichodrilus allegheniensis Cook, 1971: 381–383 ; Fig. 1 . Rodriguez & Giani 1994: 40; Fig. 10 .

Eremidrilus allegheniensis (Cook) . Fend & Rodriguez 2003: 518.

Material examined. NMC 3471, 3472, 2 dissected paratypes from the type locality, Tennessee, Franklin Co., Round Mountain Cave , (7 miles Northeast of Still Fork, Alabama); in rimstone pool, 30 July 1967 .

Remarks. Eremidrilus allegheniensis was described in detail by Cook (1971), based on four museum specimens. A paratype (USNM 43491) was reexamined by Rodriguez & Giani (1994) and the holotype (USNM 43490) by Fend & Rodriguez (2003). The two additional specimens examined here confirm several characters that effectively distinguish the eastern North American E. allegheniensis from the new western species having two spermathecal segments. The allegheniensis atrium is more elongate and tubular ( Table 2), commonly extending into adjacent segments ( Fig. 9A,B ; see also Fig. 1A in Cook 1971); it is densely covered by a thick layer of prostate glands in densely-packed, distinct clusters ( Fig. 10A ), and the ectal end (at the base of the porophore) is somewhat muscular, then narrowing within the porophore. The vasa deferentia are free for most of their length, only penetrating the atrial wall near the apical end.

Some additional characters visible in the present material also appear noteworthy. The atrial epithelium of E. allegheniensis is thick (over 20 µm) and glandular ( Fig. 10A,B ), particularly compared with that of E. artzaini , E. humboldti , and E. gilita n. spp. The spermathecae have sacciform ampullae, short ducts and unordered sperm, as in other species with two spermathecal segments ( Figs. 9A , 10F ); however, E. allegheniensis spermathecal pores terminate on distinctive papillae ( Fig. 10D,E ). Among the other described Eremidrilus species, only E. felini Fend & Rodriguez, 2003 has strongly modified spermathecal pores, but those open within laterally placed sacs (see Figs. 13 f,g in Fend & Rodriguez 2003). A pair of large (copulatory?) glands, adjacent to the ventral chaetae in XIII ( Figs. 9B , 10E ) was seen in both E. allegheniensis paratypes examined here, and a smaller pair of similar glands was present anterior to the chaetae in XII. These glands are multicellular, with conjoined ducts terminating on a small secretory surface, and resemble copulatory glands in some other lumbriculid genera (e.g. Fend et al. 2015). They have not been observed in other Eremidrilus species, but also were not mentioned in prior E. allegheniensis descriptions.

Figures

FIGURE 1. Eremidrilus artzaini n. sp. from Wildhorse Creek (A); East Fork Big Lost River (B–D, F); Summit Creek (E). A. Anterior end, external view of an unmounted worm; arrows indicate limits of clitellum. B. Chaetal pairs; left to right: III dorsal, III ventral, XII ventral. C. Atria, transverse section in X. D. Spermathecae, transverse section in XI; arrows indicate position of ventral chaetae. E. Reproductive organs, segments X–XII; both spermathecal pairs with sperm. F. Reproductive organs, segments X–XII; sperm funnels and spermatheca in XII without sperm.

FIGURE 9. Eremidrilus allegheniensis (Cook, 1971). A. Segments X–XIII of Paratype 3472, showing spermathecae and paired ventral glands. Spermathecal sperm with heads oriented to ectal wall of ampulla. Glands in XIII open slightly lateral to chaetae. B. Atrium of Paratype 3471, showing porophore and junction of anterior vas deferens with atrium (posterior vas was broken). Atrium extends into XI. Both drawings are reversed to face right for comparison with other species.

FIGURE 10. Eremidrilus allegheniensis (Cook, 1971). A. Atrium and prostate glands, Paratype 3472. B. Detail of atrium, Paratype 3471. C. Male porophore, Paratype 3471. D. Spermathecal papilla and pore, Paratype 3471. E. Spermathecal pore in XII and ventral gland in XIII, Paratype 3472. F. Spermatheca in XI, Paratype 3471. Note: specimens are facing left.

FIGURE 11. Eremidrilus species having two spermathecal segments, schematic illustration comparing position and basic morphology of reproductive organs in X–XIII.