Leodamas Kinberg, 1866

Blake, James A., 2020, New species and records of deep-water Orbiniidae (Annelida, Polychaeta) from the Eastern Pacific continental slope, abyssal Pacific Ocean, and the South China Sea, Zootaxa 4730 (1), pp. 1-61 : 35

Genus Leodamas Kinberg, 1866

Type-species: Leodamas verax Kinberg, 1866 , by monotypy.

Synonym: Branchethus Chamberlin, 1919 . Type-species: Branchethus latum Chamberlin, 1919 , by monotypy. Fide Hartman 1957.

Diagnosis. (after Blake 2017). Prostomium pointed on anterior margin, usually prolonged; most species with a single achaetous peristomial segment; immature adults of some species with two achaetous peristomial rings and adults of at least one species with vague indication of two achaetous segments. Branchiae single or with multiple branches, either from anterior thoracic setigers 4–7 or from posterior thoracic setigers or first abdominal setigers. Posterior thoracic setigers with 0–2 postsetal lobes and 0–2 subpodial lobes, never more than four lobes of both types combined; not forming ventral fringes. Thoracic neuropodial uncini large, conspicuous, arranged in one to many distinct vertical rows, with accompanying capillaries few or entirely lacking; heavy spear-like spines and bristle-topped setae absent. Abdominal neuropodia with projecting aciculae, either thin and inconspicuous or large and curved apically. Abdominal noto- or neuropodial flail setae present or absent.

Remarks. Blake (2017) redefined Leodamas and referred 29 species to the genus; an additional species was subsequently described by Sun et al. (2018) from the East China Sea. Blake (2017) divided the species into two groups: (A) species with branchiae from an anterior thoracic setiger (4–7) and thoracic neuropodial uncini typically in three or more rows and (B) species with branchiae from a posterior thoracic or anterior abdominal setiger (12–29) and thoracic neuropodial uncini typically in one or two rows. Based on Blake (2017) and Sun et al. (2018), 20 species of Leodamas are known from Group A, of which only three have been reported from depths greater than 500 m. An additional species belonging to Group A has been discovered among deep-water samples (> 1500 m) from off Brunei in the South China Sea and is here described.