Eigenmannia, D.S.Jordan & Evermann, 1896

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 : 46-47

Eigenmannia Jordan & Evermann, 1896

Adductor mandibulae. The rictalis originates in the preopercle, sympletic, quadrate and hyomandibula. The lateralmost fibers of the ventral portion of the rictalis is restricted to the anterior margin of the preopercular fossa. That section inserts solely on the coronoid process, with some lateralmost fibers associated with the buccopalatal membrane and posterior margin of the anguloarticular. The stegalis arises from the hyomandibula, metapterygoid, and quadrate; and converges into the meckelian tendon which, in turn, inserts on the coronomeckelian bone, with some anterodorsal fibers converging to the mandibular tendon (Dutra et al., 2021: fig. 41A). In E. humboldtii , E. meeki , E. macrops , E. sayona , E. trilineata , E. besouro , E. matintaperera , E. waiwai , E. nigra , and E. oradens , the stegalis overlaps only the posterior portion of the basal region of the endopterygoid not overlapping it completely; in E. microstoma , E. pavulagem , E. antonioi , E. virescens , E. guairaca , E. desantanai , E. muirapinima , E. limbata , and E. vicentespelaea , the stegalis is located laterally in relation to the basal region of the endopterygoid, overlapping it completely.

The segmentum mandibularis arises from the mandibular tendon, enters the mandible mesially and inserts on the anguloarticular and dentary; except for E. humboldtii , with the insertion restricted to the anguloarticular. The segmentum mandibularis is located dorsally to Meckel’s cartilage, extending about 50-60% of the dorsal portion of this cartilage. The course of the ramus mandibularis trigeminus nerve is lateral to the stegalis and mesial to the rictalis and malaris.

Levator arcus palatini. The levator arcus palatini has a roughly triangular shape. Within Eigenmannia , the generalized condition is the origin of the levator arcus palatini arising from the sphenotic, but including the pterosphenoid in E. muirapinima and E. vicestespelaea , or the frontal in E. humboldtii , E. pavulagem , E. nigra , E. oradens and E. limbata . The insertion occurs on the hyomandibula, and includes the preopercle in E. muirapinima and E. vicentespelaea . The relative size of origin is equal to a half of its insertion. At the insertion point, the anterolateral, anteromesial and posterolateral fibers are lateral to the malaris; while and posteromesial fibers are mesial to the latter. Among the analyzed species, the anteromesial fibers lies mesially to the malaris only in E. limbata . The posterodorsal fibers of the levator arcus palatini are mesial to the dilatator operculi, but without reaching the median portion of the levator arcus palatini in E. humboldtii , E. limbata and E. vicentespeleae . In E. pavulagem , E. antonioi , E. besouro and E. guairaca , the posterodorsal fibers of the levator arcus palatini is lateral to the dilatator operculi. In the remaining species, the levator arcus palatini is parallel to the dilatator operculi, with no overlap.