Acestridium Haseman, 1911

Rodriguez, Mónica S., Delapieve, Maria Laura S. & Reis, Roberto E., 2015, Phylogenetic relationships of the species of Acestridium Haseman, 1911 (Siluriformes: Loricariidae), Neotropical Ichthyology 13 (2), pp. 325-340 : 335

Acestridium Haseman, 1911

Diagnosis. Acestridium is diagnosed as monophyletic based on the possession of the following exclusive synapomorphies: ventral condyle of mesethmoid in the form of uniformly oval disk (char. 2.1); nasal capsule completely closed (char. 6.2); lateral ethmoid elongate and rectangular (char. 7.1); posterolateral process of lateral ethmoid short, approximately equal to on-half diameter of nasal capsule (char. 8.1); articulation between hyomandibula and neurocranium solely through prootic (char. 10.3); anterolateral margin of anterohyal concave (char. 20.1); accessory flange of first ceratobranchial small, pointed and fragile (char. 22.1); connecting bone dorsally attached to most anterior prenuchal plate (char. 27.1); neural spine of sixth vertebral centrum not articulated to posterior portion of parieto-supraoccipital (char. 28.1); dorsal fin displaced posteriorly, situated above anal fin (char. 29.1); two bifid hemal spines present on vertebral centra posterior to first anal-fin pterygiophore (char. 31.1); ossified portion of pectoral-fin spine short, just reaching beyond one-half length of first branched ray (char. 35.1); lateropterygium absent (char. 37.1); caudal fin with 12 branched rays (char. 38.1); ventral margins of paired rostral plates partially united at ventral midline anteriorly but their posterior portions diverging laterally (char. 39.1); only two postrostral plates (char. 43.2); and snout with spatulate projection (char. 51.1). In addition, there are three non-exclusive synapomorphies: presence of levator arcus palatine crest (char. 11.0); presence of large foramen in hyomandibula (char. 13.1); and interhyal absent (char. 21.0).

Acestridium dichromum + A. triplax . The clade is diagnosed as monophyletic based on the possession of one exclusive synapomorphy: the well developed and robust ribs (char. 32.1). In addition, there is also one non-exclusive synapomorphy: the terminal expansion of the tip of the rib on the sixth centrum only posteriorly (char. 30.0).

Acestridium scutatum + A. gymnogaster + A. discus + A. colombiensis + A. martini . The clade is diagnosed as monophyletic based on the possession of one exclusive synapomorphy: the weak pectoral-fin spines, hardly thicker than the first branched fin ray (char. 33.1). In addition, there is also one non-exclusive synapomorphy: the lack of serrations on the pectoral-fin spine (char. 34.0).

Acestridium discus + A. colombiensis + A. martini . The clade is diagnosed as monophyletic based on the possession of two exclusive synapomorphies: the long exposure of the mesethmoid on the dorsum of the snout, extending anteriorly beyond the mesethmoid disc (char. 5.1); and the ventral margins of the paired rostral plates completely united along the ventral midline, with their posterior portions not diverging laterally (char. 39.2). In addition, there is also one non-exclusive synapomorphy: the lateral abdominal plates close together and covering the entire ventral surface of the abdomen (char. 46.1).

Acestridium colombiensis + A. martini . The clade is diagnosed as monophyletic based on the possession of eight exclusive synapomorphies: the short and squarish lateral ethmoid (char. 7.2); the very short posterolateral process of lateral ethmoid, with its length shorter than one-half the diameter of the nasal capsule (char. 8.2); the transverse crest of hyomadibula exposed on the external surface of the cheek between infraorbital 6 and the opercle (char. 12.1); the lack of a connecting bone (char. 26.1); the pelvic-fin spines thin and fragile (char. 36.1); a caudal fin with 10 branched fin rays (char. 38.2); left and right infraorbital 1 plates more ventrally positioned and articulated with each other along the midline ventrally in front of lips (char. 41.1); and the lack of mid-dorsal series of lateral plates (char. 48.2). In addition, there is also two non-exclusive synapomorphies: the ossified portion of pectoral-fin spine as long as, or longer than, the first branched fin ray (char. 35.0); and infraorbital 1 displaced ventrolaterally and reaching and forming part of the ventral border of the snout (char. 40.1).