Distocyclus Mago-Leccia, 1978

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

Distocyclus Mago-Leccia, 1978

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 transverse ligament. 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.

The segmentum mandibularis arises from the mandibular tendon, enters the mandible mesially and inserts on the anguloarticular and dentary. The segmentum mandibularis is located dorsally to Meckel’s cartilage, extending about 40% 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 triangular shape, originating from the sphenotic and inserting in the hyomandibula ( Fig. 21 ). 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. The posterodorsal fibers of the levator arcus palatini are parallel to the dilatator operculi, with no overlap between the two muscles.

Figures

FIGURE 21 | Lateral view of dorsolateral musculature of Distocyclus conirostris (Sternopygidae), MZUSP 23316, 242.2 mm LEA. Anatomical abbreviations in Tab. 1. Scale bar = 4 mm.