Erebussau tenebricosus, Bezerra & Pape & Hauquier & Vanreusel, 2021

Bezerra, Tania Nara, Pape, Ellen, Hauquier, Freija & Vanreusel, Ann, 2021, Description and distribution of Erebussau nom. nov. pro Erebus Bussau, 1993 nec Erebus Latreille, 1810 with description of a new specie, and of Odetenema gesarae gen. nov., sp. nov. (Nematoda: Desmoscolecida) from nodule-bearing abyssal sediments in the Pacific, Zootaxa 4903 (4), pp. 542-562 : 549-550

Erebussau tenebricosus nom. nov., comb. nov.

( Figs 2 , 3 and 4 ; Tables 1 and 2)

Material examined: Three males, nine females and five juveniles. Some of these adult specimens used for the proposal of the new replacement nomen are deposited in the Ghent University Zoological Museum—Museum voor Dierkunde ( UGMD) under the codes: Male 1 (Inventory No. UGMD 104398), Male 2 (Inventory No.104399), Female 1 (Inventory No. 104400) and Female 2 (Inventory No. 104401).

Habitat and locality: Deep-sea with sediment grain size dominated by silt, containing polymetallic nodules. Specimen Male 1, was found in a sample from the GSR license area in the CCFZ during expedition SO239, Station 146, Core 11-A, 0–5 cm at an average of 4544 m depth . The species was previously found by Bussau (1993) in the Peru Basin, in February 1989 at an average of 4137 m depth .

Description: Males: Body elongated, strongly annulated, especially at anterior and posterior ends. Annulations of the anterior part of the body with triangular smooth outline.A pair of somatic setae is present on the tail. Cephalic region marked by a narrower anterior region of the body. Four stout cephalic setae are present. Amphids vesicular, with blistered fovea. Buccal cavity small and unarmed. Pharynx surrounded by many glands, impairing the description of the muscular disposition. Two or three well defined pigment spots, ventrally and subventrally disposed at the anterior portion of the intestine. Pseudocoelomocytes present, surrounding the anterior portion of the intestine. Anterior testis directed towards the anterior end, well developed. Posterior testis much smaller and reflexed. Spicules curved. Gubernaculum with caudal apophysis. No precloacal supplements. Three caudal glands contained in the tail. Phasmata-like structures located laterally at the last posterior third of the tail region, on each side of the body. These phasmata-like structures can be easily overlooked. Tail conical, long with spinneret.

Females: Similar to males in most aspects, although generally longer. Cephalic shape more round and pronounced off-set than in males. Cuticle annulation more evident than in males. No pigment spots visible. Reproductive system didelphic with reflexed ovaries. Reproductive system with a clear posterior ovary and a much smaller anterior ovary, not well developed, apparently not functional, refleting a possible pseudomonodelphic condition. Vulva with non-protruding lips, positioned close to the mid body, slightly posteriorly in most cases. No perivulvar glands observed. Uterus not well distinguished. Oviduct indistinct; ovaries antidromous with reflexed tips. Phasmata-like structures larger than in males. Female tail conical, longer than in males. Terminal spinneret with same morphology as in males but slightly elongated.

Juveniles: Similar to adults in most morphological aspects.

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Figures

FIGURE 2: Distribution of Erebussau tenebricosus nom. nov., comb. nov. Imagery reproduced from the GEBCO Grid, version 1.3.0, ETOPO1 Global Relief Model (Amante & Eakins, 2009)

FIGURE 3: Erebussau tenebricosus nom. nov., comb. nov. (Drawings of specimens code: Male 1 and Female 1) A: male habitus, arrow pointing towards phasmata; B: male anterior end, arrows pointing towards pseudocoelomocyte and pigment spot; C: female anterior end, arrows pointing towards pointing towards pseudocoelomocytes; D: female reproductive system; (Scale bars: A, B, C, D = 20 µm)

FIGURE 4: Erebussau tenebricosus nom. nov., comb. nov. (Photos of specimens code: Male 1 and Female 1) A: male habitus, arrow pointing towards pigment spots; B: male anterior end, arrow pointing towards pseudocoelomocyte; C: female reproductive system, arrow pointing towards ovary reflected end; D: male posterior end, tail pointing towards apophysis; E: female anterior end; F: female tail showing phasmata; (Scale bars A = 50 µm, B, C, D, E, F = 20 µm)