Scoloplos de Blainville, 1828

Blake, James A., 2017, Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America, Zootaxa 4218 (1), pp. 1-145 : 43-44

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. 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 in number, not in distinct rows, and accompanied by numerous crenulated capillaries; furcate setae usually present; heavy spear-like spines and bristletopped setae absent. Abdominal neuropodia with embedded, non-projecting acicula. Abdominal noto- and or neuropodial flail setae present or absent.

Remarks. The definition of Scoloplos is here emended and restricted to species having only inconspicuous spines in thoracic neuropodia accompanied with numerous capillaries, and branchiae from setiger 8–26. Leodamas , usually treated as a subgenus of Scoloplos , was raised to full generic status by Blake (2000). The latter genus has large, conspicuous spines in thoracic neuropodia, with few or no accompanying capillaries, and branchiae usually from setigers 4–6, however, another group of species has branchiae from posterior thoracic or anterior abdominal setigers. Another, but less reliable distinction between the two genera is that the abdominal neuropodial aciculae tend to be small and imbedded in Scoloplos species and larger and projecting in Leodamas species.

Pettibone (1957) distinguished between Scoloplos and Leodamas in a different manner. Scoloplos species were said to have a papilla in the middle of the thoracic neuropodial lobes, while Leodamas species lacked these papillae. While many species of Leodamas do have low, rounded postsetal lobes and lack papillae or cirriform lobes throughout much of the thoracic region, most species develop prolonged postsetal lobes in posterior thoracic setigers. According to Hartman (1948), the thoracic neuropodial postsetal lobes of Leodamas verax Kinberg , the type-species of Leodamas , are triangular and undivided. This structure has been confirmed in the present study.

Thus, the presence of a prolonged postsetal lobe on the thoracic neuropodium of the type-species of Leodamas would appear to preclude its use as a definitive character for Scoloplos sensu stricto.

The genus Scolaricia was originally distinguished from Scoloplos on the basis of having flail setae in abdominal neuropodia ( Eisig, 1914). However, these setae have now been found in several genera and since the character is homoplasic within the Orbiniidae and not unique to Scolaricia , the genus was referred to synonymy with Scoloplos by Day (1973).

In the present study, two previously undescribed species of Scoloplos were encountered: S. bathytatus , n. sp., and S. suroestense , n. sp. Another species, S. armiger , the type species, has been reported from South America ( Ehlers, 1901; Rozbaczylo, 1985), but was not found in the present study.