Scoloplos de Blainville, 1828

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 : 29

Genus Scoloplos de Blainville, 1828

Type species: Lumbricus armiger Müller, 1776 , by monotypy.

Synonym: Scolaricia Eisig, 1914 . Type-species: Scolaricia typicus Eisig, 1914 , by monotypy. Fide Day 1973.

Diagnosis. (Emended). Prostomium pointed, usually prolonged; single achaetous peristomial ring. Branchiae first present from middle or posterior thoracic setigers or from abdominal setigers (8–26). 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 neurosetae including blunt, inconspicuous uncini, few or many in distinct rows; accompanied by few to many crenulated capillaries; furcate setae usually present; heavy spear-like spines and bristle-topped setae absent. Abdominal neuropodia with embedded, non-projecting acicula. Abdominal noto- and or neuropodial flail setae present or absent.

Remarks. The type-species of Scoloplos , S. armiger has been reported globally despite there being no recent description of the species from the type-locality in Norway. Although most descriptions of S. armiger include the presence of subpodial papillae along the body, there have been two different patterns reported for the neuropodial spines or uncini that occur in thoracic neuropodia. One pattern is where there are numerous rows of uncini and fewer capillaries in thoracic neuropodia ( Hartman 1957; Hartmann-Schröder 1996). A second pattern is where there are only a few uncini that typically occur in the ventral-most part of the fascicle and in the first or second setal row ( McIntosh 1910; Pettibone 1963); capillaries are numerous in this second pattern and the uncini may not occur in all thoracic neuropodia. Both of these patterns have been reported widely and it is not apparent which of these actually refers to S. armiger from the type-locality in Norway. Recent ecological investigations and results of molecular sequence data in northern Europe suggest that at least three distinct populations or species of Scoloplos are present ( Kruse & Reise 2003; Bleidorn et al. 2006).

Bleidorn et al. (2006, 2009) also provided molecular results on some orbiniids from the eastern Pacific that suggested that specimens identified as S. armiger from California are distinct from the European populations and represent additional undescribed species. To date, none of the various species suggested by these studies in Europe and California have been described or redescribed, including specimens from the type locality of S. armiger .

Among approximately 28 known species of Scoloplos , only three have been recorded from deep-sea habitats: S. ehlersi Blake, 1985 from the Galápagos Rift hydrothermal mounds, S. bathytatus Blake, 2017 from the Weddell Sea, Antarctica, and S. intermedius ( Hartman, 1965) from the western North Atlantic. Two new species, S. californiensis n. sp. from off northern California and S. sparsaciculus n. sp. from off Brunei in the South China Sea have been discovered in the deep-water samples treated in the present study and are described. Both of these new deepwater species belong to the group having a reduced number of thoracic uncini in thoracic neuropodia.