Alvinonemertes claudiae, Sagorny & Döhren & Rouse & Tilic, 2022

Sagorny, Christina, Döhren, Jörn von, Rouse, Greg W. & Tilic, Ekin, 2022, Cutting the ribbon: bathyal Nemertea from seeps along the Costa Rica margin, with descriptions of 2 new genera and 9 new species, European Journal of Taxonomy 845 (1), pp. 132-174 : 157-158

Alvinonemertes claudiae gen. et sp. nov.

urn:lsid:zoobank.org:act:1BA9AE85-AB72-4736-9132-79796011C259

Figs 8G , 10H–N

Diagnosis

Alvinonemertes claudiae gen. et sp. nov. can be attributed to the genus Alvinonemertes gen. nov. based on molecular data. It differs from all other species in the genus by its very translucent body that is pale yellowish. It can be differentiated from A. dariae gen. et sp. nov. by the characteristics given in the diagnosis of A. dariae .

Etymology

For Claudia Müller, lab technician at the Institute of Evolutionary Biology, University of Bonn. Acknowledging her support in the immunohistology lab over many years and also in recognition of her devotion to the care of our live annelid and nemertean worm cultures.

Material examined

Holotype NORTHEASTERN PACIFIC OCEAN • ♂ (fixed in formaldehyde and prepared as 15 slides with transverse sections, see cybertype); hydrothermal vents at South Cleft , Juan de Fuca Ridge; 44.659° N, 130.364° W; depth ca 2250 m; 31 Jul. 2016; Greg Rouse leg.; collected by ROV Doc Ricketts, Dive 875; SIO-BIC N283 (ex SIO-BIC N231).

Paratypes NORTHEASTERN PACIFIC OCEAN • 1 spec. (fixed in formaldehyde); same collection data as for holotype; SIO-BIC N284 (ex SIO-BIC N231) • 3 specs (ethanol); same collection data as for holotype; GenBank: ON036050 , ON021868 ; SIO-BIC N231 .

Cybertype Images of serial sections of holotype: https://doi.org/10.5281/zenodo.5346520.

Description

Specimens 6 mm long and 0.7 mm in diameter. Body cylindrical. One pair of cephalic furrows, forming the shape of an anteriorly open V. Head not demarcated from rest of body, rounded. Body translucent. Internal organs, such as gut and gonads, well visible through body wall ( Fig. 8G ).

Epidermis in foregut region 10 µm thick. Body wall composed of two muscle layers (outer circular, inner longitudinal). Esophagus opening subterminal, ventral; stomach without pouches; pylorus longer than stomach; intestinal cecum with ventral unpaired anterior pouch under stomach and one pair of lateral pouches ( Fig. 10K ); intestine with lateral diverticula. Precerebral septum closed. Rhynchocoel wall with very thin outer circular and inner longitudinal muscle layers, rhynchocoel almost extending to posterior end of body. Proboscis with outer circular, middle longitudinal, and inner circular muscle layers. Proboscis with 10 proboscis nerves; central stylet and two accessory stylet pouches present, four to five accessory stylets per pouch ( Fig. 10M–N ). Stylet basis circular in cross section. Proboscis pore subterminal, ventral ( Fig. 10H ). Nervous system with thin outer neurilemma, without neurochord cells ( Fig. 10J ); dorsal commissure short, ventral commissure broad. Lateral nerve cords without accessory nerve ( Fig. 10K ). Cerebral ganglia and lateral nerves in longitudinal muscle layer ( Fig. 10J–K ). Eyes absent. Cerebral organs less than half the size of brain lobes, close in front of brain. Paired cerebral canal simple, unforked, opens ventro-laterally into cephalic furrows ( Fig. 10I ). Apical organ present, unpaired; cephalic gland extending to brain ( Fig. 10H, J ). Circulatory system consisting of cephalic loop, mid-dorsal vessel not forming vascular plug (( Fig. 10L ). Testes sac like, alternating with intestinal diverticula, situated ventrally.

Ecology

Associated with hydrothermal vents, alongside other vent fauna such as the annelids Branchinotogluma tunnicliffeae (Pettibone, 1988) (e.g., SIO-BIC A7716), Paralvinella sulfincola Desbruyères & Laubier, 1993 (e.g., SIO-BIC A7724) and Ridgeia piscesae Jones, 1985 (e.g., SIO-BIC A7719).

Remarks

The new species is attributed to the genus Alvinonemertes gen. nov. based on the executed phylogenetic analyses. In the concatenated analysis, A. claudiae gen. et sp. nov. is sister to A. christianeae gen. et sp. nov. ( Fig. 7 ).

Figures

Fig. 8. Live images of eumonostiliferous hoplonemerteans collected along the Costa Rica margin and the NE Pacific. A. Chernyshevia escarpiaphila sp. nov., paratype (SIO-BIC N112). B. Chernyshevia escarpiaphila sp. nov., paratype (SIO-BIC N266). C. Octocoral Paragorgia sp. (SIO-BIC Co3054) with several specimens of Alvinonemertes dariae sp. nov., holotype (arrows; ex SIO-BIC N262). D. Alvinonemertesdariaesp.nov.,holotype(exSIO-BICN262).E.Antipathariancoral(SIO-BICCo3031) with specimens of Alvinonemertes dagmarae sp. nov., holotype (SIO-BIC N260). F. Alvinonemertes christianeae sp. nov., holotype (SIO-BIC N253). G. Alvinonemertes claudiae sp. nov., holotype (ex SIO-BIC N231). H. Alvinonemertes tatjanae sp. nov., holotype (SIO-BIC N119). I. Eumonostilifera (SIO-BIC N259). J–L. Tetrastemma sundbergi sp. nov., holotype (SIO-BIC N256) whole animal (J), dorsal view of head (K), and ventral view of head (L). M. Tetrastemma polyakovae sp. nov. (MZUCR Nemertea Collection MZUCR-101-01).N. Tetrastemma polyakovae sp. nov., holotype (SIO-BIC N258), with everted proboscis. O. Eumonostilifera (SIO-BIC N109).

Fig. 10. A–G. Alvinonemertes dariae gen. et sp. nov., holotype (SIO-BIC N281), transverse histological sections. H–N. Alvinonemertes claudiae gen. et sp. nov., holotype (SIO-BIC N283), transverse histological sections. A. Anterior tip of head with proboscis pore. B. Brain region. C. Anterior brain region with cerebral canal (arrowhead). D. Stomach region with excretory canal. E. Posterior body region with testes. F. Lateral nerve cord with accessory nerve in stomach region. G. Proboscis armature, accessory stylet pouches with accessory stylets. H. Anterior tip of head with proboscis pore. I. Region anterior to cerebral ganglia with well-visible cerebral canal (arrowhead). J. Anterior brain region. K. Pyloric region. L. Proboscis and mid-dorsal vessel in stomach region. M. Proboscis armature, circular basis of central stylet. N. Proboscis armature, accessory stylet pouches with accessory stylets. Abbreviations: an = accessory nerve; ap = accessory stylet pouch; as = accessory stylet; bl = blood vessel; br = brain; cg = cephalic glands; cm = circular muscle layer; co = cerebral organ; dl = dorsal brain lobe; ec = excretory canal; gd = gonoduct; i = intestine; ic = intestinal cecum; ip = intestinal pouches; lm = longitudinal muscle layer; ln = lateral nerve cord; mv = mid-dorsal vessel; p = proboscis; pe = proboscis epithelium; pp = proboscis pore; py = pylorus; rc = rhynchocoel; rd = rhynchodaeum; sb = stylet basis; st = stomach; t = testis; vl = ventral brain lobe. Scale bars: A–G = 100 µm; H–N = 30 µm.

Fig. 7. Maximum likelihood (ML) tree for the monostiliferan supermatrix based on the concatenated four gene dataset (16S, COI, 18S, H3). Black circles indicate nodal support of 100/100/1.0; asterisks indicate nodal support of either 100/ or /1.0. Alternative branches found in the BI analysis are given as blue dotted lines. Sonnenemertes cantelli Chernyshev, Abukawa & Kajihara, 2015 and Micrura callima Sundberg & Gibson, 1995 were used for outgroup rooting. Specimens belonging to new species are given in bold. Specimen-ID, sampling locality, and depth (for deep-sea species) are provided.