Genus: Plesionectes SACHS & MADZIA, 2025
Etymology: Greek, plesion, "close, near", referring to its plesiosaur affinities and Greek, nektes, "swimmer."

Species: longicollum SACHS & MADZIA, 2025
Etymology: Latin, longus, "long" and Latin, collum, "neck", in reference to its long neck, comprising of 43 vertebrae.

Holotype: SMNS 51945

Locality: Holzmaden, Esslingen District, Baden-Württemberg State, southewestern Germany.

Horizon: Lias εII1, 'Koblener'.

Biostratigraphy: Dactylioceras tenuicostatum Zone, D. semicelatum Subzone.

Age: Lower Toarcian Stage, Upper Lias Epoch, lower Jurassic.

Material: Nearly complete, largely articulated skeleton, comprising a patialy exposed skull including the exoccipital-opisthotic, quadrtaes and parts of the squamosals, 41 articulated vertebrae, 4 pectoral vertebrae, 20-21 dorsal vertebrae, 2 sacral vertebrae and 39 caudal vertabrae and associated ribs, gastralia, incomplete pectoral girdle with interclavicle, left scapula and part of right scapula, fragmentary coracoids, incomplete pelvic girdle with complete left ilium, part of right ilium, both ischia, incomplete pubes, complete left front and hind limb, disarticualted distal right front limb and right hind limb.