Oligobregma Kudenov and Blake, 1978

Blake, James A., 2023, New Species of Scalibregmatidae (Annelida) from Slope and Abyssal Depths off Eastern Australia, Records of the Australian Museum (Rec. Aust. Mus.) 75 (3), pp. 271-298 : 279-282

Genus Oligobregma Kudenov and Blake, 1978

Type species. Pseudoscalibregma aciculata Hartman, 1965 . Designated by Kudenov & Blake (1978).

Diagnosis. Body elongate and arenicoliform with rows of elevated pads on dorsal and ventral segmental surfaces. Prostomium T-shaped with two prominent frontal horns; eyes present or absent; nuchal organs present. Peristomium achaetous, surrounding prostomium dorsally and forming upper and lower lips of mouth ventrally. Branchiae absent. Parapodia with well-developed dorsal and ventral cirri; interramal papilla present or absent. Capillaries present in all parapodia; furcate setae present anterior to capillaries from an anterior setiger: 2, 3, 4 or later; some species with short, slender, blunt, or pointed spinous setae anterior to capillaries of setigers 1, 2, or 3, representing homologues of furcate setae found on following setigers. Pygidium with four or more anal cirri.

Remarks. With the addition of O. tasmania , transferred from Asclerocheilus , and four new species described here, there are now a total of 17 known species of Oligobregma , which now surpasses Asclerocheilus (with 15 species) as the largest genus in the family. Most species of Oligobregma are from the deep sea, with 13 of the 17 species reported from lower continental slope or abyssal depths. The morphology and distributions of all 17 species are compared in Table 2 .

Tables

Table 2. Morphological comparison of 17 known species of Oligobregma.Abbreviations: Ant, anterior; Atl,Atlantic; CCZ, Clarion-Clipperton N, north; NeuroC, neuropodial cirri; NotoP, notopodia; NotoC, notopodial cirri; NeuroP, neuropodia; NW, northwest; Pap, papilla; Post, Set, setiger; W, western.

species	anterior setigers with acicular spines	prostomium	first furcate	segmental annulation patterns	posterior parapodia	pygidium	distribution & references
			setae
species with acicular spines on setigers 1–2
O. aciculata ( Hartman, 1965)	Both rami; spines hirsute	2 short rounded frontal	?Set 3	Not reported	NotoC short, rounded; NeuroC,	Unknown	W North Atl, abyssal, 4850 m;
		lobes			triangular, pointed; with		Hartman, 1965
					interramal Pap
O. oculata Kudenov & Blake,	Both rami	T-shaped, with digitiform	Set 3	Set 1 smooth; Set 2	NotoC narrow, as long as wide;	“At least” 2	S of New Caledonia, 57 m;
1978		lateral lobes		biannulate; Set 3	NeuroC digitate, 3 times as long	anal cirri	Kudenov & Blake, 1978
				triannulate; rest with	as wide; large intPap
4 or 5 annulations
O. pseudocollare Schüller &	NotoP only	With 2 laterally directed	Set 3	Set 1–3 smooth; Set 4–9 tri-	Short conical dorsal and ventral	No cirri	Southern Ocean; Scotia and
Hilbig, 2007		rounded lobes		to quadriannulate,	cirri	observed	Weddell Seas, 753–3050 m;
				thereafter with 5			Schüller & Hilbig, 2007
				annulations
species with acicular spines on setigers 1–3
O. aristata sp. nov.	Both rami; spines with	2 short forwardly directed	Set 5–6	Set 1 a single large medial	NotoC large, inflated, with	Unknown	Off Australia lower
	terminal arista	lobes; these notched in		pad; set 2 uniannulate; set	nipple-like tip directed dorally;		continental slope and
		holotype		3–4 triannulate; set 5–10	NeuroC asymmetrical, nipple-		abyssal depths, 2793–4031
				inflated, obscured; set	like tip directed laterally		m; This study
				11–22 tri- to quadriannulate
O. collare (Levenstein, 1975)	NotoP only; spines hirsute	2 short forwardly directed	Set 4	Set 1–2 smooth; set 3 to	NotoC short, bluntly triangular;	Up to 8 cirri	Southern Ocean, Antarctica,
		rounded lobes		mid- body triannulate; post	NeuroC short, conical; with		1622–6070 m; Levenstein,
				set quadriannulate	interramal Pap		1975; Blake, 1981
O. mucronata Blake, 2015	Both rami; spines w/	2 short, forwardly directed	Set 4	Set 1–2 uniannulate; set 3,	NotoC large, triangular, NeuroC	4 anal cirri	East Antarctic Peninsula,
	terminal arista	rounded lobes		biannulate; set 4 and	large, triangular, with broad		323–912 m; Blake, 2015
				following quadriannulate	base; with interramal Pap
O. notiale Blake, 1981	NotoP only	2 enlarged, diverging lateral	Set 4	Set 1 smooth to irregular;	NotoC large inflated lobe;	5 ventral cirri	Southern Ocean, Antarctica,
		lobes		rest quadriannulate	NeuroC small, conical lobe;		18–923 m; Blake, 1981
					with large interramal Pap
O. profunda sp. nov.	Both rami of first row; rarely	2 short rounded lobes,	Set 5–6	Set 1–3 smooth; set 4–end	NotoC and NeuroC erect;	4 anal cirri	Off eastern Australia,
	in second row of set 1;	subapical		tri- to quadriannulate	triangular with pointed tips		Tasmania to New South
	NeuroP of set 1‒2, rarely 3;						Wales, 3881‒4176 m. This
	first row only.						study.