Alvinonemertes dariae Sagorny & Döhren & Rouse & Tilic 2022, gen. et sp. nov.
Creators: name: Sagorny, Christina
name: Döhren, Jörn von
name: Rouse, Greg W.
name: Tilic, Ekin
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Nemertea
Pilidiophora
Heteronemertea
Lineidae
Alvinonemertes
Alvinonemertes dariae

description: Alvinonemertes dariae gen. et sp. nov.
urn:lsid:zoobank.org:act: D94F4501-3FB4-4F11-8D9E-EB75E20EEB34
Figs 8C–D, 10A–G
Diagnosis
Alvinonemertes dariae gen. et sp. nov. is identified as member of the genus Alvinonemertes gen. nov. based on internal morphology and molecular data. It differs from all other species in the genus by its body coloration and pigmentation. It can be differentiated from A. claudiae gen. et sp. nov. (the only other species with internal data) by the length of the rhynchocoel (⅓ of body length vs whole body), the number of accessory stylets per pouch (2 vs 4-5) and the position of the cerebral organs (alongside brain vs in front of brain).
Etymology
Named for Dr Daria Krämer, acknowledging her contributions to nemertean taxonomy.
Material examined
Holotype
COSTA RICA • ♂ (fixed in formaldehyde and prepared as 23 slides with transverse sections, see cybertype); methane seep Parrita Seep; 9.03268° N, 84.62127° W; depth 1407 m; 5 Nov. 2018; Jorge Cortés and Drew Bewley leg.; collected by HOV Alvin, Dive 4990; associated with an octocoral identified as Paragorgia Milne Edwards, 1857 (SIO-BIC Co3054); SIO-BIC N281 (ex SIO-BIC N262).
Paratypes
COSTA RICA • 3 specs (fixed in ethanol); same collection data as for holotype; GenBank: ON186252, ON036048, ON021865; SIO-BIC N262 • 1 spec. (fixed in ethanol); same collection data as for holotype; MZUCR Nemertea Collection MZUCR-105-01 (ex SIO-BIC N262).
Cybertype Images of serial sections of holotype: https://doi.org/10.5281/zenodo.5346500.
Description
Specimens 15 mm long and 0.7 mm in diameter. Body flattened. One pair of cephalic furrows. Head not demarcated from rest of body, rounded. Body coloration orange with several red pigment spots distributed over body surface. Internal organs well visible through body wall (Fig. 8D).
Epidermis in foregut region 30 µm thick. Body wall composed of two muscle layers (outer circular, inner longitudinal; Fig. 10B). Esophagus opening subterminally; stomach without pouches (Fig. 10B, D); pylorus shorter than stomach; intestinal cecum with unpaired ventral process under stomach; intestine with several lateral pouches (Fig. 10E). Excretory system confined to foregut region, canals outside musculature (Fig. 10D). Precerebral septum closed. Rhynchocoel wall with two very thin muscle layers (outer circular, inner longitudinal), rhynchocoel approximately ⅓ of body length. Proboscis with outer circular, middle longitudinal, and inner circular muscle layers. Proboscis with central and accessory stylets. Stylet basis circular in cross section, two accessory stylet pouches with two stylets per pouch (Fig. 10G). Proboscis nerves not visible. Proboscis pore subterminal, ventral (Fig. 10A). Nervous system with thin outer neurilemma, without neurochord cells (Fig. 10B–C); dorsal and ventral commissures approximately same size. Lateral nerve cords with accessory nerve (Fig. 10F). Cerebral ganglia and lateral nerves in longitudinal muscle layer (Fig. 10B). Eyes absent. Cerebral organs less than half the size of brain lobes, alongside brain (Fig. 10C). Paired cerebral canal simple, unforked, opens laterally into cephalic furrows (Fig. 10C). Apical organ present, unpaired; cephalic glands extending to brain (Fig. 10A–C). Blood system consisting of cephalic loop, mid-dorsal vessel not forming vascular plug. Testes sac like, alternating with intestinal diverticula, ventral (Fig. 10E). Females unknown.
Ecology
The species seems to occur in close association with octocoral Paragorgia sp. as several nemertean specimens were sampled from one colony (Fig. 8C).
Remarks
Alvinonemertes dariae gen. et sp. nov. is attributed to the genus Alvinonemertes gen. nov. based on the executed phylogenetic analyses. In the concatenated analysis, this species is sister to the other four newly described species attributed to the genus Alvinonemertes (Fig. 7).
description: Published as part of 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, pp. 132-174 in European Journal of Taxonomy 845 (1) on pages 153-155, DOI: 10.5852/ejt.2022.845.1959, http://zenodo.org/record/7258852