Main Content
< Top page

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Trichodrilus

Trichodrilus Claparede, 1862 (ref. ID; 1257, 3692, 7809)

Family Lumbriculidae (ref. ID; 1257, 5939, 6422, 7809)

ref. ID; 1923

Spermathecal pores in segment 11, or 11 and 12. Prostomium elongate. Single species. (ref. ID; 1923)

ref. ID; 7809

Trichodrilus Claparede, 1862 is a genus of lumbriculid oligochaetes containing 19 European species which appear to be restricted to ground water and subteranean fresh-water habitats; the genus is defined in Cook (1968) and specific descriptions are available in Cook (1971). Representatives of Trichodrilus have been recorded only twice in North America (Brinkhurst & Cook, 1966). Kindred (1918) reported on a species from Concord, Illinois, which he tentatively identified as Trichodrilus allobrogum Claparede, 1862. The Smithsonian Institution's holdings of the genus include Kindred's single specimens (USNM26279) which cannot be identified to species because its male genitalia are not visible in his sections, and an incompletely mature specimen from Washington, D.C. (USNM26347) which, while it can be recognized definitely as a different species from Kindred's worm because it has a single pair of spermathecae, cannot be identified to species. (ref. ID; 7809)
  1. Trichodrilus allobrogum Claparede, 1862 (ref. ID; 1923, 3692) reported author and year? (ref. ID; 5939)
  2. Trichodrilus allegheniensis Cook, 1971 (ref. ID; 7809 original paper) reported author and year? (ref. ID; 5939)
  3. Trichodrilus cantabrigiensis (Beddard, 1908) (ref. ID; 1257) reported year? (ref. ID; 1928)
  4. Trichodrilus capilliformis Rodriguez & Giani, 1994 (ref. ID; 7265)
  5. Trichodrilus claparedei Hrabe, 1937 (ref. ID; 6618)
  6. Trichodrilus culveri (ref. ID; 5939)
  7. Trichodrilus diversisetosus Rodriguez, 1986 (ref. ID; 7265)
  8. Trichodrilus icneorum Beddard, 1920 (ref. ID; 1257)
  9. Trichodrilus itchaensis Sokol., 1973 (ref. ID; 6651)
  10. Trichodrilus leruthi Hrabe, 1937 (ref. ID; 6618)
  11. Trichodrilus macroporophorus Hrabe (ref. ID; 6609)
  12. Trichodrilus montenegrinus Karaman, 1973 (ref. ID; 7645 original paper)
  13. Trichodrilus pragensis (Vejdovsky, 1875) (ref. ID; 3692)
  14. Trichodrilus stammeri Hrabe, 1937 (ref. ID; 6618)
  15. Trichodrilus strandi Hrabe, 1936 (ref. ID; 6618)

Trichodrilus allegheniensis Cook, 1971 (ref. ID; 7809 original paper) reported author and year? (ref. ID; 5939)

Descriptions

Length about 20 mm; diameter about 0.85 mm anteriorly, 1.1 mm at the clitellum. About 70 segments. Prostomium produced into a probosis-like extension about 180 µm long, 65 µm diameter. All segments except the first two bear a secondary annulus; ratio of the lengths of the anterior to the posterior parts of each segment is about three to one. Setae single-pointed, 167-200 µm long, 3.4-5.6 µm thick, with the node in the middle third of the seta (ratio of the lengths tip to node/total is 0.368-0.418; mean 0.38). Clitellum weakly developed on segments 1/2X-1/2XIII. Male pores paired behind the ventral setae of segment X, situated on the summits of a pair of porophores. Two pairs of spermathecal pores are located behind the ventral setae on segments XI and XII. The body wall is relatively thick; cuticle 2.5 µm, epidermis 28 µm, circular muscle 5.3 µm, and longitudinal muscle layer is 35 µm thick. Pharyngeal glands are present in segments IV to VII. Posterior lateral blood vessels are absent. Two pairs of testes are present in segments IX and X. One pair of ovaries is present in segment XI. Two pairs of male funnels, located in septa IX/X and X/XI, are of equal size and very small (about 30 µm wide at the mouth). Two pair of vasa deferentia, 17-27 µm in diameter, lie along the atria for about two-thirds of their length, penetrate through the prostate gland layer, and join the atria apically to subapically. The posterior pair of vasa deferentia penetrate septum X/XI before returning to X. The atria are elongate, cylindrical structures, 700-1000 µm long, 55-75 µm in diameter, with the muscle layer about 6.5 µm thick. Atria terminate in short ducts, devoid of a prostate gland covering, which open onto the summits of paired, ovoid porophores about 100 µm long and 135 µm wide (antero-posteriorly). The atria are covered with a diffuse layer of prostate cells about 60 µm thick. The atria curve either anteriorly, penetrating into segment IX, or posteriorly, penetrating into segment XI. Two pairs of spermathecae, situated in segments XI and XII, have discrete ducts 170-220 µm long, 65-75 µm in diameter, and pear-shaped ampullae 450-530 µm long, 220-300 µm maximum diameter. The posterior pair of spermatheca tend to be slightly smaller than the anterior pair although both are functional in copulation (both pairs are full of sperm in the four types). Sperm sacs extend anteriorly into segment VII or VIII, and posteriorly into about segment XVII. The first pair of nephridia are located in segment XIII. (ref. ID; 7809)

Remarks

Trichodrilus allegheniensis n. sp., is distinctly different from the above two specimens, and from all the European species, because of its elongate, proboscis-like prostomium, its long tubular atria, and its two pairs of spermathecae. The habitat of Tichodrilus, ground water and subterranean waters, can render the genus susceptible to a high degree of speciation by effectively isolating populations which are close geographically. This appears to have been the case in Europe where 19 species are known, many of them from the type locality only. The occurrence of the genus in North America indicates the possibility that a number of species await discovery on this continent, and that the paucity of our present knowledge of the group is probably a reflection of their cryptic mode of life. (ref. ID; 7809)

Etymology

From the Allegheny subregion of the Nearctic. (ref. ID; 7809)

Type specimens

  • Holotype: United States National Museum (USNM) 43490. Round Mountain Cave, Franklin Coutry, Tennessee. (Seven miles Northeast of Still Fork, Alabama); in rimstone pool; collected 30 July 1967. (ref. ID; 7809)
  • Paratypes: USNM43491. One whole mount, data as for holotype. National Museum of Natural Sicences, National Museums of Canada, 3471 and 3472. Two dissected individuals, data as for holotype. (ref. ID; 7809)