Tetranemertes pastafariensis, Cherneva & Ellison & Zattara & Norenburg & Schwartz & Junoy & Maslakova, 2023

Cherneva, Irina, Ellison, Christina I., Zattara, Eduardo E., Norenburg, Jon L., Schwartz, Megan L., Junoy, Juan & Maslakova, Svetlana A., 2023, Seven new species of Tetranemertes Chernyshev, 1992 (Monostilifera, Hoplonemertea, Nemertea) from the Caribbean Sea, western Pacific, and Arabian Sea, and revision of the genus, ZooKeys 1181, pp. 167-200 : 167

Tetranemertes pastafariensis sp. nov.

Fig. 6

Material examined.

Type material is deposited with the Smithsonian Institution's National Museum of Natural History. Anterior ends are preserved for histology and posterior - in 95% ethanol: holotype CB055_18_04 (USNM 1618675), paratype CB055_18_06 (USNM 1618676). See Table 1 for additional specimens, accession numbers, and Table 2 for collecting information .

Diagnosis.

Tetranemertes pastafariensis sp. nov. differs from all other described species of this genus, except T. ocelata sp. nov. by uniformly pale yellow to orangish yellow body color. It differs from T. ocelata sp. nov. by having smaller ocelli. Easily differentiated from other species with DNA sequence data (Table 5 ).

Description.

External appearance of live specimens. Long, thin, thread-like body can stretch more than 10 cm in length and is up to 0.5 mm wide at the head; body up to 1 mm wide. Body rounded or slightly compressed in cross-section. The caudal end is rounded. Body color is uniform orangish yellow, paler towards the anterior end (Fig. 6A, B ). Blood is colorless.

When placed in a dish, often forms a writhing tangle. When mechanically disturbed it contracts into a knot, and secretes transparent sticky mucus. Moves by ciliary gliding, often with the anterior end of the head raised from the surface, the inflection point coinciding with the lateral indentation of the anterior cephalic furrow. The head region anterior to the anterior furrow is less contractile, causing an obvious discontinuity in width when the anterior end of the animal is contracted. Regeneration ability not known.

The head is somewhat triangular, spear-shaped, resembling head of a snake. The anterior part of the head is demarcated from the body by both width and an anterior ventrolateral cephalic furrow. The body is dorso-ventrally flattened in front of the anterior cephalic furrow; and thicker posterior to it, with a dorsal bulge corresponding to the brain. The cerebral ganglia, tinged pale pinkish orange, are visible through the body wall. The anterior margin of the head is bluntly pointed, slightly indented by the rhynchostomopore.

Cerebral organ furrows are fused ventrally forming a single cephalic furrow (Fig. 6B , arrowhead). The cephalic furrow wraps around the lateral sides of head, and is barely visible from the dorsal side as a pair of lateral indentations. On the ventral side it forms a shallow anteriorly-pointed “V” anterior to cerebral ganglia. Posterior cephalic furrow is lacking. Mouth and rhynchopore are combined into a single anterior ventral rhynchostomopore.

Ocelli (20-40) are arranged in four longitudinal rows, two on each side of the head (Fig. 6B ), reaching to posterior margin of cerebral ganglia (Fig. 6D ), black in transmitted light. The medial rows are not visible from the ventral side. Cerebral organs present, clearly visible in specimens compressed under a cover slide (Fig. 6D ).

Rhynchocoel and proboscis. Rhynchocoel does not exceed 1/3 of body length. The proboscis is transparent, with two distinctive regions separated by a proboscis bulb. The anterior region is much shorter than the posterior, and the bulb has a length to width ratio of ~ 1. Proboscis armed with a single central stylet and two pouches, each holding two or three accessory stylets. The central stylet shaft is straight with spiral grooves. The stylet basis is rod-shaped, with a width to length ratio of ~ 1:4 to 1:5, with characteristic shallow fork posteriorly (Fig. 6C ). One individual had a cylindrical basis with rounded posterior (not shown). Stylet to basis length ratio is ~ 1:1 (n = 2).

Reproduction. No data.

Habitat.

Free living, marine benthic species, inhabiting shallow coral reef rubble (1-7 m depth). Tends to stretch in the crannies of the substratum.

Geographic distribution.

Currently only known from Bocas del Toro, Panamá.

Etymology.

The species is named after its resemblance to the Flying Spaghetti Monster, the deity of the Pastafarian religion.

Figures

Figure 6. Tetranemertes pastafariensis sp. nov. A external appearance in life of individual CB 055 _ 18 _ 04 B anterior end in ventral view of individual CB 055 _ 18 _ 06 showing cephalic furrow (arrowhead, cf) C stylets of individual CB 055 _ 18 _ 08 showing a posteriorly bilobed basis and sculpted stylets D head of individual CBdT 0059 compressed under a glass slide showing number and distribution of eyes, as well as cerebral organs (arrowheads) and pinkish cerebral ganglia. Abbreviations: cg - cerebral ganglion, co - cerebral organ. Scale bars: 5 mm (A); 1 mm (B, D); 25 μm (C).