Type species: Tharyx acutus Webster & Benedict, 1887, by monotypy.
Diagnosis. (after Blake 2018). Prostomium conical; peristomium elongate, with pair of grooved dorsal tentacles arising on posterior margin; first pair of branchiae typically arising immediately posterior to dorsal tentacles either on posterior margin of peristomium or on setiger 1; abdominal segments sometimes beadlike. Noto- and neurosetae arising close to one another, not widely separated. Setae include simple capillaries in anterior and middle setigers, acicular spines present in posterior setigers either in both noto- and neuropodia or only in neuropodia. Long, natatory-like setae present or absent. Spines typically short, curved, sometimes geniculate or sickle-shaped, narrowing to rounded irregularly notched or sub-bidentate tip; tips with pair of stunted or rounded knobs but not with two distinct teeth. Capillaries may accompany posterior spines or are absent, not alternating with spines when present. Pygidium with terminal anus and small ventral lobe or disk. Several species with black pigment markings on posterior lateral margin of peristomium.
Remarks. Following the revision by Blake (1991), species of Tharyx were restricted to those having knobtipped or sub-bidentate acicular spines. Species having simple and serrated capillaries that were formerly included in Tharyx were moved to the genera Aphelochaeta and Monticellina (now Kirkegaardia), respectively. The status of the genus Tharyx and additional species were recently described by Blake & Göransson (2015) and Blake (2018) bringing the total number of known Tharyx species to 15. One new species has been identified from the CCFZ collections and is here described.