Caulleriella jormungandri, Grosse & Kongsrud & Alvestad & Eilertsen & Budaeva, 2025

Caulleriella jormungandri sp. nov.

urn:lsid:zoobank.org:act:FF0D1D4D-39A7-48ED-A5DD-E457E1A47D20

Figs 3–7 View Fig View Fig View Fig View Fig View Fig

Diagnosis

Body long and slender, not threadlike, posteriorly flattened; three peristomial rings, first segment chaetigerous; 3–6 bidentate spines per neuropodium from chaetiger 4, 3–4 per notopodium from chaetiger 16.

Etymology

In Norse mythology, Jörmungandr is a sea serpent or worm and a child of Loki. As a marine worm discovered in the Loki’s Castle vent field, Caulleriella jormungandri sp. nov. is named after this mythological creature.

Material examined

Holotype

ARCTIC MID-OCEAN RIDGE • Loki’s Castle hydrothermal vent field; 73.56633° N, 8.15946° E; 2350 m depth; 11 Jul. 2015; collected by ROV; sample GS15-AGR09; fixed in 96% ethanol; DNAvoucher: CaH03; ZMBN 157421 View Materials .

GoogleMaps

Paratypes

ARCTIC MID-OCEAN RIDGE • 1 spec.; Loki’s Castle hydrothermal vent field; 73.5662° N, 8.1585° E; 2300 m depth; 14 Jul. 2008; collected by ROV; sample BIODEEP08-LC-ROV11; fixed in 96% ethanol; ZMBN 157515 View Materials • 1 spec.; Loki’s Castle hydrothermal vent field, Barite Field ; 74.5661° N, 8.1585° E; 2357 m depth; 7 Aug. 2009; collected by ROV; sample H2DEEP09-ROV08; fixed in 96% ethanol; ZMBN 157516 View Materials GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: LC01; ZMBN 157517 View Materials GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: LC04; ZMBN 157518 View Materials GoogleMaps • 1 spec.; same data as for preceding; ZMBN 157520 View Materials GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: LC02; ZMBN 157513 View Materials GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: LC03; ZMBN 157514 View Materials GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: LC05; ZMBN 157519 View Materials GoogleMaps • 3 specs; same data as for preceding; mounted on SEM-stubs; ZMBN 157681 to 157683 GoogleMaps • 1 spec.; Loki’s Castle hydrothermal vent field; 73.5662° N, 8.1610° E; 2335 m depth; 17 Jul. 2010; collected by ROV; sample GS10-ROV06-b; fixed in 96% ethanol; ZMBN 157521 View Materials GoogleMaps • 1 spec.; same data as for preceding; 73.5668° N, 8.1605° E; 2373 m depth; 19 Jul. 2010; collected by ROV; sample GS10-ROV10; fixed in 96% ethanol; ZMBN 157522 View Materials GoogleMaps • 109 specs; same data as for preceding; 73.5663° N, 8.1610° E; 2350 m depth; 11 Jul. 2015; collected by ROV; sample GS15- AGR09; fixed in 96% ethanol; ZMBN 154069 View Materials GoogleMaps • 3 specs; same data as for preceding; DNA vouchers: K49, K50, K51; no repository (specimens used for DNA) GoogleMaps • 1 spec.; same data as for preceding; DNAvoucher: CaH01; ZMBN 157419 View Materials GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: CaH02; ZMBN 157420 View Materials GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: CaH04; ZMBN 157422 View Materials GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: CaH05; ZMBN 157423 View Materials GoogleMaps • 1 spec.; Loki’s Castle hydrothermal vent field, barite field; 73.5664° N, 8.1618° E; 2342 m depth; 10 Jul. 2017; collected by ROV; sample GS17- ROV18-SS4; fixed in 96% ethanol; ZMBN 157524 View Materials GoogleMaps • 8 specs; Loki’s Castle hydrothermal vent field, barite field, chimney; 73.5666° N, 8.1624° E; 2344 m depth; 12 Jul. 2017; collected by ROV; sample GS17-ROV21-R1; fixed in 96% ethanol; ZMBN 157523 View Materials GoogleMaps • 2 specs; Loki’s Castle hydrothermal vent field, barite field, worm forest; 73.5663° N, 8.1624° E; 2342 m depth; 18 Jul. 2018; collected by ROV; sample GS18-107-ROV26; fixed in 96% ethanol; ZMBN 157597 View Materials GoogleMaps • 1 spec.; same data as for preceding; ZMBN 157598 View Materials GoogleMaps • 2 specs; same locality as for preceding; 73.5662° N, 8.1621° E; 2341 m depth; 22 Jul. 2018; collected by ROV; GS18-107-ROV28; fixed in 96% ethanol; ZMBN 157599 View Materials GoogleMaps • 1 spec.; Loki’s Castle hydrothermal vent field, oasis, worm forest; 73.5671° N, 8.1617° E; 2356 m depth; 1 Jul. 2019; collected by ROV; GS19-108-ROV25; fixed in 96% ethanol; ZMBN 138216 View Materials GoogleMaps • 7 specs; same data as for preceding; fixed in 96% ethanol; ZMBN 138212 View Materials GoogleMaps .

GoogleMaps

Other material

ARCTIC MID-OCEAN RIDGE • 37 specs; 68.70600° N, 11.61100° W; 1811 m depth; 16 Mar. 1984; collected by dredge; sample HM84.03.16-2; fixed in formaldehyde and transferred to 75% ethanol; ZMBN 144543 View Materials GoogleMaps • 6 specs; 69.60600° N, 9.91000° W; 2212 m depth; 26 Jul. 1986; collected by dredge; sample HM86.07.26-1; fixed in formaldehyde and transferred to 75% ethanol; ZMBN 157644 View Materials GoogleMaps • 1 spec.; 69.10616° N, 9.9120° W; 2174–2204 m depth; 17 Sep. 2011; sample M85-3-1155; fixed in 96% ethanol; DNA-voucher: MG1000; SMF 32807 About SMF GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: MG1001; no repository (specimen used for SEM) GoogleMaps • 1 spec.; 69.103° N, 9.9225° W; 2169–2172 m depth; 17 Sep. 2011; collected with Agassiz trawl; sample M85-3-1160; fixed in 96% ethanol; DNA-voucher: MG763 no repository (specimen used for SEM) GoogleMaps • 1 spec.; 71.1110° N, 7.92933° W; 2160–2203 m depth; 17 Sep. 2011; fixed in 96% ethanol; collected with epibenthic sledge; sample M85-3-1159; DNA-voucher: MG1041; SMF 32878 About SMF GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: MG1042 no repository (specimen used for SEM) GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: MG1043 no repository (specimen used for SEM) GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: MG1044; SMF 32879 About SMF GoogleMaps • 1 spec.; same data as for preceding; DNA-voucher: MG1045; SMF 32880 About SMF GoogleMaps .

Description

Holotype complete, 12 mm long, 0.7 mm wide, 72 segments. Other complete specimens ranging 3–12 mm in length and 0.2–0.7 mm in width for 47–77 segments. Colour in ethanol light tan to brown, rarely dark grey ( Figs 3–4 View Fig View Fig ). Body long and slender, without any distinct enlargement, cylindrical in cross section in anterior and middle body, dorsoventrally flattened in posterior region ( Figs 3–4 View Fig View Fig ). Anterior 8–13 segments 3–4 times wider and higher than long, round in cross section, lengthening to 2–3 times wider and higher than long in midbody. Posterior 20 segments 4–5 times wider and 2 times higher than long, oval to rectangular in cross section. Dorsal groove or ridge absent. Thin ventral groove accompanied by dark line sometimes present, depending on fixation.

Prostomium half to two thirds as long as peristomium, conical, rounded on anterior margin, without rings; eyespots absent ( Figs 5A–C, F View Fig , 6B–C View Fig ); nuchal organs simple round slits at posterior lateral margins ( Fig. 5C–E View Fig ). Peristomium as long as 3–4 anterior segments, as high and wide as long, with three distinct rings of similar length, anterior ring overlapping prostomium dorsally, middle ring overlapping posterior ring dorsally between tentacles, posterior ring partially fused to chaetiger 1. Dorsal tentacles arising from third peristomial ring, well separated from one another and anterior to first pair of branchiae ( Figs 5A–C, F View Fig , 6B–C View Fig ). First pair of branchiae arising between posterior margin of peristomium and first segment postero-lateral to tentacles. Second pair of branchiae arising from chaetiger 1, dorsal and slightly posterior to parapodia ( Fig. 5A–B, F View Fig ). Subsequent branchiae similarly placed, present only in anterior part of body.

Parapodia biramous, neuropodia and notopodia well separated, notopodia forming low shoulders in anterior chaetigers, neuropodia lateral anteriorly and nearly reaching ventral position in posterior chaetigers. Capillary chaetae 8–10 per neuropodium and notopodium from chaetiger 1, decreasing in number posteriorly; finely fibrillated along one edge ( Fig. 7A–B View Fig ). On neuropodia and notopodia without spines, capillary chaetae are arranged in two rows, posterior capillaries twice as long as anterior ones ( Fig. 7A View Fig ). Bidentate spines from chaetiger 4, 3–6 per neuropodium; from chaetiger 16, 3–4 per notopodium; long, relatively thick, slightly curved with basal shoulder, main fang thick, pointed, at 45° angle from shaft, apical tooth short, pointed, in prolongation of alate flange on convex side of shaft ( Fig. 7C–G View Fig ). Companion capillaries arise between most spines.

Pygidium with terminal anus and rounded ventral lobe ( Fig. 6A View Fig ).

Methylene blue staining pattern

The entire body retains a light blue colour with dark blue circles around neuropodia and notopodia anteriorly. Some dark intersegmental ventral bands are sometimes visible on the first few segments.

Comparative remarks

At present, nine species of Caulleriella have been reported from depths over 500 m ( Blake 2021), including the new species described in the present paper. One species is known from the Pacific Ocean, four from the Southern Ocean and four from the Atlantic Ocean. Caulleriella jormungandri sp. nov. is most similar to C. eltaninae Blake, 2018 and C. kacyae Blake, 2018 from the Southern Ocean in having three peristomial rings. Caulleriella jormungandri differs from C. eltaninae in that the first segment is the first chaetiger (achaetous in C. eltaninae ), in the presence of notopodial spines and in the lack of pygidial cirri. Caulleriella jormungandri mainly differs from C. kacyae by the lack of pygidial cirri and the number and distribution of spines in neuropodia (up to 6 from segment 4 in the former vs up to 6 from segment 18 in the latter) and notopodia (up to 4 from segment 16 in the former vs up to 2 from segment 105 in the latter). Caulleriella jormungandri is easily distinguished from other deep-sea North Atlantic species ( Caulleriella filliformia Blake, 2021 , Caulleriella pintada Blake, 2021 and Caulleriella rodmani Blake, 2021 ) by the body shape and the peristomium, as all these other species have threadlike bodies and a single peristomial ring.

Distribution and habitat

Caulleriella jormungandri sp. nov. is a common species at Loki’s Castle vent site in areas with lowtemperature diffuse venting, where it is found in association with dense aggregations of other polychaetes (worm forest), in particular Sclerolinum contortum and Nicomache lokii . Additional specimens were collected from five localities close to Jan Mayen in depths between 1800 and 2200 m ( Fig. 1 View Fig ). No indication of hydrothermal activity was recorded from the localities near Jan Mayen, suggesting that Caulleriella jormungandri is not strictly associated with hydrothermal environments.