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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Thalassodrilides

Thalassodrilides Brinkhurst & Baker, 1979 (ref. ID; 5945 original paper)

Family Tubificidae: Subfamily Limnodriloidinae (ref. ID; 5882)

Family Tubificidae: Subfamily Aulodrilinae Hrabe emm. Brinkhurst (ref. ID; 5945)

ref. ID; 5945

Setae bifid. Genital setae absent. Body wall naked. Vasa deferentia wide, about as long as club-shaped atria that terminate in muscular protrusible pseudopenes. Prostate glands small, at or just ventral to union of vasa deferentia and atria. Spermathecae small or absent, sperm in irregular masses. Coelomocytes absent. (ref. ID; 5945)

Remarks

The genus Thalassodrilus was erected by Brinkhurst (1963) to accommodate the European Rhyacodrilus prostatus Knollner. Cook (1974) described its subsequent history and retained the genus for prostatus, gurwitschi (Hrabe) from the Adriatic and Black Seas, and the newly described belli from Baja California. Erseus (1975) redescribed prostatus, discovering that the prostate at the union of the atrium and vas deferens of each male duct was associated with atrial tissue projecting beyond the main mass of the atrium and not with the vas deferens as previously illustrated. He also described a second posterior prostate close to the numerous penial setae and, quite logically, transferred the species to the genus Phallodrilus, which he then redefined. As this was the type species of Thalassodrilus, a new generic name is required for the assemblage containing T. belli, T. gurwitschi, and a new species from the Atlantic coast of the United States at Indian River Bay, Rehoboth Bay, Delaware. According to Hrabe (1971) the genus also includes Limnodriloides roseus Pier. and L. pectinatus Pier., two inadequately described taxa at present located as species inquirendae with Spiridion (q.v.). Another species, T. modricensis described by Hrabe (1973) from Yugoslavia is placed in Spiridion by Erseus (personal communication). The relationship between this genus and Spiridion Knollner can only be resolved once the latter is redescribed from fresh material as it has not been seen since its original description in 1935. In a personal communication Erseus points out that the prostate glands are broadly attached to the atria and this and other characteristics relate Thalassodrilides to the Aulodilinae. (ref. ID; 5945)

Type species

Limnodriloides gurwitschi Hrabe, 1971 (ref. ID; 5945)
  1. Thalassodrilides belli (ref. ID; 5882)
  2. Thalassodrilides gurwirschi (ref. ID; 5882)
  3. Thalassodrilides gurwitschi (Hrabe, 1971) (ref. ID; 6618)
  4. Thalassodrilides milleri Brinkhurst & Baker, 1979 (ref. ID; 5945 original paper)

Thalassodrilides belli (ref. ID; 5882)

Descriptions

Marine species. (ref. ID; 5882)

Thalassodrilides gurwirschi (ref. ID; 5882)

Descriptions

Marine species. (ref. ID; 5882)

Thalassodrilides gurwitschi (Hrabe, 1971) (ref. ID; 6618)

Descriptions

Marine species. (ref. ID; 6618)

Thalassodrilides milleri Brinkhurst & Baker, 1979 (ref. ID; 5945 original paper)

Descriptions

Length to 10-12 mm. Breadth 0.5 mm. Segments 46 or more. Prostomium conical shorter than broad at prostomium. Body wall naked. Clitellum not observed. Setae slightly sigmoid, bifid, with the upper tooh shorter and thinner than the lower, which becomes very broad posteriorly; setae two to three (maximum of four) per bundle anteriorly and posteriorly. Setae increase in size to IV-VII (75 µm) and decrease posteriorly to about 60 µm. Vasa deferentia short and thick (310-410 µm x 36 µm) widening to 45-60 µm at the sperm funnel. Sperm funnel 66 µm long, widening to 65-75 µm at the open end. Vasa deferentia enter atria apically through short (38 µm) narrow (14 µm) constrictions; atria cylindrical, 490x27 µm proximally, 60 µm diameter basally, no ejaculatory ducts. Distal ends of male duct folded, forming pseudopenes. Prostate glands possibly present, attached close to union of atria and vasa deferentia. Spermathecae small, bilobed, 173x67 µm at widest, 51 µm medially, sperm in oriented bundles. (ref. ID; 5945)

Remarks

The species differs from the type in the possession of spermathecae, and from T. belli in having fewer setae, with short upper teeth rather than teeth of equal length. Other material from Puerto Rico and Panama is being studied by C. Erseus and D.R. Spencer (personal communication). The presences or absence of prostate glands in both the type and the new species requires confirmation. (ref. ID; 5945)

Etymology

For Mr. P. Miller, who collected the species. (ref. ID; 5945)