Tubifex tubifex (Müller, 1774) is a freshwater oligochaete worm that is common in the Great Lakes. It is a tubificid worm that has dorsal bundles with hairs and pectinate chaetae and bifid ventral chaetae beginning in II. This species has short, tub-shaped granular penis sheaths. There are 3–5 pectinate chaetae and 1–6 hairs which may be hispid in the dorsal bundles. Anterior ventral bundles contain 3–6 or more chaetae which decreases to 2 posteriorly, and the upper tooth is as long as but thinner than the lower tooth; there is sometimes a small intermediate spine. The shape of the penis sheaths may seem like a vase or bulb with a reflexed hood, but the granulations should be evident regardless of the shape of the short penis sheath.
There have been many revisions to Tubifex over the years. Some species in the genus have been moved to Tasserkidrilus, and one from Tasserkidrilus now belongs to Varichaetadrilus (Timm 2006). There may be many cryptic species represented by T. tubifex. Two alternate forms have been described in the keys: forma blanchardi, which lacks hairs and pectinate chaetae, instead having only bifid dorsals; and forma bergi, which has mildly pectinate dorsal chaetae and sparse hair chaetae. There also may be some specimens that lack pectinate dorsal chaetae and instead have bifid chaetae with hairs. Over time, some of these forms may be recognized as distinct species, such as T. blanchardi, which was originally a distinct species until revisions in the 1970s made it a form of T. tubifex, and it was recently recognized as a distinct species through genetic analysis (Marotta 2009).
T. tubifex is identified by the short, tub-shaped granular penis sheaths, hairs that may or may not be hispid, and pectinate chaetae, although the pectinations may be missing in some specimens. The ventral chaetae have teeth equal in length, but the upper tooth is thinner than the lower.
T. tubifex is found in a variety of habitats, although often marginal, oligotrophic, or hypereutrophic. When in very polluted habitats, it is often sympatric with Limnodrilus hoffmeisteri.
This species occurs in all five Great Lakes.
Without the presence of reproductive features, many tubificid worm species can only be identified as “immature tubificid with or without hair.” The chaetal structure is similar to Ilyodrilus templetoni, but the anterior ventral chaetae of I. templetoni have the upper tooth longer than the lower, not equal, and the penis sheaths of I. templetoni are long and conical, not short, tub-shaped granular penis sheaths.
T. tubifex could be confused with other members of Tubifex, although they have distinct features that help to separate them. T. ignotus is a long, thin worm rarely found in the Great Lakes, with U-shaped pectinate chaetae and starting in X, the hispid hair chaetae are 2–3 times longer than the diameter of the segment. The penis sheath is short and tub-shaped but not granular. T. nerthus is a coastal species that is mainly known for having anterior ventral chaetae with the upper tooth twice as long as the reduced lower tooth. Tasserkidrilus americanus and T. superiorensis have hairs and pectinate chaetae, but have longer, conical penis sheaths.
Some forms of T. tubifex lacking pectinate chaetae may appear similar to a West Coast species, Ilyodrilus frantzi, which has a wide variety of chaetal forms that may be influenced by conductivity (bifid dorsals, bifid with short hair, pectinate dorsals with hair, or intermediate between hair and bifids). I. frantzi has a short, truncated cone-shaped penis sheath, which has been compared to a frying pan. Although we are unlikely to find it in the Great Lakes, those looking through keys may be drawn to compare the two species.
Based on penis sheaths, T. tubifex may be confused with some worms with all bifids and no hairs. The penis sheaths of Isochaetides freyi are reminiscent of T. tubifex in their general shape, since they are both short cuticular penis sheaths that are about as long as they are broad, with a reflexed hood. The penis sheaths of I. freyi are not granular and sometimes appear square instead of round due to creases that run from the apex to the base. It is quite easy to tell them apart because I. freyi lacks hair chaetae in the dorsal bundles and has long, thin spermathecal chaetae in X, but it is a useful reference for the shape of the penis sheaths. Another species with a similar penis sheath shape is Teneridrilus columbiensis, which is only found in the Columbia River, Oregon. It has all bifid chaetae, but the chaetae of II have short upper teeth and very long, thick, recurved lower teeth, and spermathecal chaetae in X. Though it won’t be found in the Great Lakes, it represents another species with the right shape of penis sheath, though it lacks granulation.
T. tubifex is a large freshwater oligochaete.
Yes, this species does have a barcode reference from the Great Lakes.
This work is licensed by Susan Daniel under a Creative Commons Attribution-NonCommercial 2.0 Generic License.
Figure 1. A picture of the short, tub-shaped penis sheaths, although here the round openings are most visible, with the bulb of the penis sheath slightly visible. Ideally, look closer to see the shape and the granulations better. (A picture of this will be available at a later date.)
Marotta, R., Crottini, A., Prada, V., and M. Ferraguti. A morphological reappraisal of Tubifex blanchardi Vejdovský, 1891 (Clitellata: Tubificidae) Acta Zool. 2009; 9: 179–188.
Kathman, R.D., and R.O. Brinkhurst. 1998. Guide to Freshwater Oligochaetes of North America. pp. 142–143, 112, 124, 139–141, 164–167, 144–147.
Stimpson, K.S., D.J. Klemm, and J.K. Hiltunen. 1982. A Guide to the Freshwater Tubificidae (Annelida: Clitellata: Oligochaeta) of North America. pp. 22–23, 51–52, 28, 45.
Timm, T. 2006. A Nearctic tubificid Varichaetadrilus harmani (Loden) n. comb. in a Dutch wetland, with remarks on Tubifex tubifex (Müller) Annelida: Oligochaeta). Zootaxa 1281: 21-39.
