Ilyodrilus templetoni
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Figure 1. An unmounted I. templetoni with a thickened clitellum. It is not possible to identify to species without mounting on a slide to find the penis sheaths.
This work is licensed by Susan Daniel under a Creative Commons Attribution-NonCommercial 2.0 Generic License.
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Figure 2. The penis sheaths of I. templetoni are very thin and may be hard to see. They are conical, easily crumpled, and the ends may be irregular or broken. This one happened to protrude from the body wall, providing an unusually clear view of the structure.
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Figure 5. The posterior dorsal bundles have fewer hairs and chaetae than anteriorly. The chaetae may be bifid instead of pectinate, and the teeth are generally shorter and thicker.
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Figure 7. The posterior ventral chaetae are bifid with the upper tooth shorter and thinner or equal to the lower tooth.
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Ilyodrilus templetoni
Taxa description
Ilyodrilus templetoni (Southern, 1909) is a freshwater oligochaete worm that is common in the Great Lakes and throughout North America. It is a tubificid worm that has dorsal bundles with hairs and pectinate chaetae and bifid ventral chaetae beginning in II. This species has conical penis sheaths in XI that may be somewhat irregular or broken. There are 3–4 pectinate chaetae and 1–4 hairs in the dorsal bundles. Anterior ventral chaetae (II and III) have 3–4 bifid chaetae with the upper tooth longer and thinner than the lower tooth, becoming equal from IV or V and possibly shorter and thinner than the lower tooth posteriorly. Some specimens may lack pectinations on the dorsal chaetae and appear to have hairs and bifid chaetae. I. templetoni is the only species from this genus in the region.
Distinguishing features
I. templetoni is identified by the conical penis sheaths, the long, thin upper tooth of the anterior ventral chaetae, and dorsal bundles with hairs and pectinate chaetae, although the pectinations may be missing in some specimens.
Habitat
This species is common in lakes and rivers, especially in enriched habitats. It can often be found with Limnodrilus hoffmeisteri.
Lake occurrence
Lakes Erie, Huron, Michigan, and Ontario.
Similar species
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 Tubifex tubifex, but T. tubifex has short, tub-shaped granular penis sheaths. Based on penis sheaths, I. templetoni may be confused with Tasserkidrilus americanus, which also has long, thin penis sheaths. The penis sheaths of T. americanus are usually longer and more well-defined than those of I. templetoni, which may be wispy and crumpled, and T. americanus’s also have a sub-terminal opening. Another similar species is Tasserkidrilus superiorensis, but that species has a cylindrical penis sheath with a cup-like hood at the proximal end. T. americanus and T. superiorensis may also have ventral chaetae with an additional spine, and I. templetoni does not. If the specimen has bifid dorsal chaetae instead of pectinate chaetae, it should still be identifiable as I. templetoni since there are no oligochaetes in this region with hairs, bifid chaetae, and conical penis sheaths.
Relative size
I. templetoni is a relatively large freshwater oligochaete.
Does it have a barcode reference from the Great Lakes?
Yes, this species does have a barcode reference from the Great Lakes.
References
Kathman, R.D., and R.O. Brinkhurst. 1998. Guide to Freshwater Oligochaetes of North America. pp. 164–165, 114, 124, 142–145.
Stimpson, K.S., D.J. Klemm, and J.K. Hiltunen. 1982. A Guide to the Freshwater Tubificidae (Annelida: Clitellata: Oligochaeta) of North America. pp. 28, 45.