Steatogenys Boulenger, 1898

Peixoto, Luiz Antônio Wanderley & de Pinna, Mário, 2022, Patterns of diversification and phylogenetic structure in the dorsolateral head musculature of Neotropical electric eels (Ostariophysi: Gymnotiformes), with a myological synonymy, Neotropical Ichthyology (e 210009) 20 (1), pp. 1-117 : 41-42

Steatogenys Boulenger, 1898

Adductor mandibulae. The malaris arises from the mid-dorsal portion of the hyomandibula and preopercle. Its insertion occurs on the posteromedial portion of the antorbital bone by a fibrous attachment. Its mesialmost fibers converge onto a small endomaxillary ligament, less than one-third the length of the malaris which, in turn,

inserts on the posteromedial portion of the maxilla.

The rictalis originates in the preopercle, sympletic, quadrate and hyomandibula. The lateralmost fibers of the rictalis surpass the anterior margin of the preopercular fossa and reach the posterior portion of the same bone. That section inserts mainly on the coronoid process, but with some lateral fibers on the anguloarticular and buccopalatal membrane. The stegalis arises from the hyomandibula, sphenotic, pterosphenoid, parasphenoid, and metapterygoid. Anteriorly, the stegalis differentiates into a poorlydifferentiated intersegmental aponeurosis, dorsally entering the mandibular tendon and ventrally the meckelian tendon which, in turn, inserts onto the coronomeckelian bone. The stegalis is located laterally in relation to the basal region of the endopterygoid and adductor arcus palatini, overlapping those structures completely.

The segmentum mandibularis is located dorsally to Meckel’s cartilage, extending about a half of the dorsal portion of the cartilage, but not associating with it. The ramus mandibularis trigeminus nerve is mesial to all sections of the adductor mandibulae, segmentum facialis.

Levator arcus palatini. The levator arcus palatini is roughly parallelogram shaped, originating from the ventral margin of the frontal and sphenotic and inserting onto the hyomandibula. The origin of the levator arcus palatini is approximately 50% wider than its insertion. At the insertion, the anterolateral, posterolateral and anteromesial fiber bundles of the levator arcus palatini are lateral to the malaris, while its posteromesial bundles are medial to it. The levator arcus palatini is positioned mesially to the dilatator operculi, where the anterior margin of the latter exceeds the median portion of the former.