Tjalfiella Mortensen, 1910

Bezio, Nicholas & Collins, Allen G., 2024, Redescription of the deep-sea benthic ctenophore genus Tjalfiella from the North Atlantic (Class Tentaculata, Order Platyctenida, Family Tjalfiellidae), Zootaxa 5486 (2), pp. 241-266 : 252

Genus Tjalfiella Mortensen, 1910

Grammatical gender— feminine

Type species— TJalfiella tristoma from Mortensen (1910): 249–253, plates. 1–10

Etymology— From the Danish Tjalfe, on which Mortensen based the name. This originated from the earlier Tjalfe expedition to Greenland on the vessel Tjalfe. “Tjalfe is a renowned figure in Northern Mythology (the companion of the good Thor on his journey to Utgård)” ( Mortensen 1912: 2).

Included species (1)— TJalfiella tristoma Mortensen, 1910

Description— Tjalfiellidae compressed in the stomodeal axis and “U” shaped; with two large aboral arms that lack oral grooves, chimney-like with flat tops, and extend perpendicularly from the main axis of the body; two tentacles (one sheathed in each respective aboral arm) that lack tentilla; statocyst sunken into a deep cavity in the center of the aboral face of the animal; hermaphroditic gonads developing into four pairs of external globular pockets centered around the statocyst on the aboral face; genital brood cavities may appear as rows of externalized pockets lining the edge of the oral skirt; meridional canals reduced to short diverticula from perradial canals; branching canals present, but rather sparse, showing no anastomoses; lack ctene rows in maturity.

Remarks— Mortensen (1912) following a relatively short original (1910) description, provides highly detailed and extensive morphological/developmental description based on microscopy and histology of many specimens and his drawings are sufficient to recognize and describe the genus when observed from a deep-sea submersible platform with high-definition imagery. No other genera have been assigned to the family Tjalfiellidae .