Unveiling a hidden wanderer in the NE Atlantic: a new species of Scalibregma (Annelida, Scalibregmatidae) Author Bonifácio, Paulo text Zootaxa 2026 2026-01-05 5741 1 159 172 https://doi.org/10.11646/zootaxa.5741.1.6 journal article 314842 10.11646/zootaxa.5741.1.6 b17a0741-6da3-4d4e-beb8-53e09d9c4de2 1175-5326 19164633 752E2199-BF6D-4D0E-8740-DF20E18011B9

TABLE 2. Morphological characters (based on Blake 2025) for all valid species in Scalibregma with branchiate segment from 3 to 5 and S. celticum (4 pairs of branchiae). “?” indicates uncertain information. Abbreviations: aLmo, anterior lobe of mouth; ant, anterior(ly); dors, dorsal(ly); elong, elongate; gls, glands; int, internal; lat, lateral(ly); perist, peristomium; pigm, pigment(ed); pLmo, posterior lobe of mouth; post, posterior(ly); prost, prostomium; ch(s), chaetiger(s); seg(s), segment(s); ventr, ventral(ly). Present study observations indicated with “*”.

	S. stenocerum	S. hanseni	S. lanai	S. drouali sp. nov.	S. celticum
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Prostomium	Narrow ant end;	T-shaped; horns	T-shaped; horns	T-shaped; horns	T-shape; horns
	horns close	projected lat	projected ca. 45	projected lat or ant-	projected lat or
	projected ant		degrees	lat	ant-lat
Eyes	2 eyes, each V-	Eyes absent	2 eyes, as patches	2 eyes, each V-	2 eyes, each V-
	shaped			shaped	shaped
Frontal horns	Elong, slender;	Elong, slender;	Elong, slender;	Elong, slender; about	Elong, slender;
	longer than prost	about as long as	about as long as	as long as prost	slightly longer than
	length*	prost length*	prost length*	length*	prost length*
Peristomium	Smooth, 2 rings	With 2 dors	With 2 dors rings,	With 2 multilobed	With 2 multilobed
	apparent dors	rings, partially	partially covering	dors rings encircling	dors rings encircling
	and ventr; ventr	covering post	post prost	prost, covering eyes	prost, covering eyes
	encompassing	prost		and post prost; ventr	and post prost; ventr
	mouth			bordering mouth	bordering mouth
Oral	Not described;	Mouth ventr,	Mouth a short	aLmo formed by	Mouth a short
morphology	Fig. 6 of Bertelsen	oval with broad	transversal slit;	a paired triangular	transversal slit
	and Weston (1980)	ant and post lips	with aLmo post to	lobes with very small	between perist and
	show mouth		first perist ring as	central pad; pLmo	ch 1; aLmo with
	with vertical slit		row of 6–8 short	formed by a central	long medial fold;
	bordered lat by		lobes; pLmo with	plicated pad with	pLmo with long
	perist		1 row short lobes	about 6 lobes	lobes on venter of
			attached to large		ch 1
			ant lobed pad
Segmental	4 annuli in Figs	Ant chs with	Ch 1–2 with 3	Ch 1 with 3 annuli,	Ch 1 with 3 annuli,
annulations	2B, C of Bertelsen	4 annuli;	annuli, then 4	following 4 annuli;	following 4 annuli;
	and Weston (1980)	following with	annuli with some	post 5 annuli; last 3	far post 5 annuli
		5–6 annuli	5 annuli far post	annuli
Branchia	Chs 3 to 5,	Chs 3 to 5,	Chs 3 to 5, dense;	Chs 3 to 5, dense;	Chs 2 to 5, dense;
	dense; pinnate,	simple; few		pinnate, each pinna	arborescent
	each pinna	branches		with additional
	with additional			bifurcations
	bifurcations
Branchia size	?	1<2<3	1~2<3	1~2<3	1<<2,3,4
Dorsal/ventral	Middle and post	Short triangular	Small, rounded	Small, subtriangular	Small, rounded
cirri	cirri inflated	from ch 13–14,	from ch 14–15,	to blunt from ch16–	from ch 15–16,
	becoming elongate	then elongate,	then longer and	17; both quickly gets	then triangular and
	in far post ch; int	lanceolate post;	digitiform post;	full size (in about	lanceolate post; int
	gls not reported	with int yellow	with pigm int gls	3–5 chaetigers); in	gls present
		gls		post about same size
				of parapodia; int gls
				absent
Interramal	Present	Present	Present	Present	Present
papillae
Acicular chaetae number in ch 1 and 2	Ch 1–2, short, slender, blunt tips; 2–6	Ch 1–2, curved, blunt tips; 4–6 in ch 1, 6–8 in ch 2	Ch 1–2, short, pointed tips; 8–9	Ch 1–2, short, slender, blunt tips; 5 in ch 1, 9–11 in ch 2	Ch 1–2, short, blunt tips; 7 in ch 1*, 13–14 in ch 2*
Lyrate number	Up to 14	7–8 in ch 3	4–6 post ch	Up to 13	12 in ch 25*
		8–12 further back
Tines of lyrate chaetae	Unequal size	Unequal size	Equal size	Unequal size	Unequal size
Capillaries	Smooth	Hirsute	Smooth	Smooth with some hirsute	Hirsute and some smooth*
Body pigment	Not reported	Ch 3–5 with dors yellow tranverse pigm bands; dorsal and ventral cirri with yellow gls	Annular rings with or without small pigm gls; inconspicuous	No pigm or gls observed	Patches of pigm vent parapodia on ch 4–6; dorsally on ch 4–5.
Posteriormost region	?	?	Last 2–3 segs cirriferous and achaetous	With 2 segs cirrigerous and achaetous, tri annuli; one without chaetae or cirri	With 2–3 segs cirrigerous and achaetous; 1–3 preanal segs lacking all features
Pygidium	At least 3 anal cirri	Rounded, with ca. 10 short lobes; with 5 anal cirri	Anus with short lobes; with 3 long anal cirri (1 ventr and 2 mid-ventr)	With crenulated ring around anus; with 6 anal cirri (3 different lengths) inserted ventr	With crenulated ring around anus; with 5 long anal cirri, inserted ventr
Distribution	W Atlantic (SE USA, N Carolina to Florida); 17– 218 m depth.	NE Atlantic (Norwegian sea, shelf and slope); 497–1,243 m depth	SW Atlantic (SE Brazil); 38–100 m depth	NE Atlantic (SW France to Moroccan coast); 55–102 m depth	NE Atlantic (UK, France, Mediterranean Sea); 6–89 m depth* (down to 300 m (OBIS 2025)
Reference	Bertelsen and Weston (1980), Kudenov (1984), Blake (2025)	Bakken et al. (2014), Blake (2025)	Mendes et al. (2023), Blake (2025)	Present study	Mackie (1991), Blake (2025), present study