Flectonotus, Miranda-Ribeiro, 1926
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publication ID |
https://doi.org/ 10.1016/j.jcz.2022.03.003 |
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persistent identifier |
https://treatment.plazi.org/id/038F878E-FFC6-FFFA-127E-E938FF78F9CD |
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treatment provided by |
Felipe |
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scientific name |
Flectonotus |
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3.3. Osteological features of Flectonotus View in CoL
Sphenethmoid. Owing to the relatively wider frontoparietals, all but the dorsomedial margin of sphenethmoid is overlapped by the anterior ends of the frontoparietals ( Fig. 1G and H View Fig ). The anterolateral border of the sphenethmoid is narrowly and incompletely overlapped by the nasals ( Fig. 1G and H View Fig ). Ventrally, the sphenethmoid is extensively ossified in the rostral region. Its leading margin is more narrowly separated from the maxillary arcade and it underlies nearly the entirety of the vomers ( Fig. 2G and H View Fig ). The bony lateral walls of the braincase terminate at about the midlength of the orbit in Flectonotus pygmaeus , whereas they are shorter in Fl. fitzgeraldi ( Fig. 2G and H View Fig ).
Nasals. The nasals are relatively much smaller in Flectonotus than in Fritziana ; thus, more of the nasal capsules is exposed and the nasals are broadly separated from one another ( Fig. 1G and H View Fig ). An attenuate maxillary process is in contact ( Fl. pygmaeus ) or not ( Fl. fitzgeraldi as in Fr. goeldii ) with the preorbital process of the pars facialis of the maxilla ( Fig. 3G and H View Fig ). The posterior margin of the nasal slightly overlaps the lateral margin of the sphenethmoid.
Frontoparietals. These paired bones are narrowly separated medially obscuring most of the frontoparietal fontanelle.
Parasphenoid. The cultriform process is uniform in width ( Flectonotus fitzgeraldi ) or slightly broader at the midlength of the orbital region ( Fl. pygmaeus ) ( Fig. 2G and H View Fig ). Anteriorly, the cultriform process narrows gradually, terminating on the sphenethmoid. The terminus of the cultriform process in Fl. pygmaeus is irregularly acuminate, whereas it is more acuminate in Fl. fitzgeraldi . In both species, the posteromedial process of the pterygoid is blunt and does not form the ventromedial margin of the foramen magnum.
Vomers. The acuminate anterior process is short, curved, and broadly separated from the maxillary arcade. Both the pre- and postchoanal processes terminate in a sharp point. The prechoanal process is longer than the postchoanal process in Flectonotus fitzgeraldi , but the processes are about the same length in Fl. pygmaeus . The vomers are narrowly separated in Fl. fitzgeraldi and broadly separated in Fl. pygmaeus . The dentigerous processes are notably small in Fl. pygmaeus and bear only three teeth, whereas Fl. fitzgeraldi has larger processes bearing four or five teeth; in both taxa, the dentigerous processes are horizontal in orientation ( Fig. 2G and H View Fig ).
Premaxillae. The pars dentalis of each premaxilla bears 7–11 ( Fl. fitzgeraldi ; Fig. 2H View Fig ) or 9–11 ( Fl. pygmaeus ; Fig. 2G View Fig ) teeth and is overlapped posterolaterally by the anterior end of the pars dentalis of the maxilla. The longitudinal axes of the alary processes do not diverge anterolaterally from one another in frontal view; they are parallel. In lateral aspect, the alary processes are convex anteriorly. The distal ends of each palatine process are rounded and narrowly separated from one another.
Maxillae. The pars facialis is high broad and extends for about less than a half the length of the maxilla. A short process (preorbital) of the pars facialis may extend toward the maxillary process of the nasal, reaching it ( Fl. pygmaeus ) or not ( Fl. fitzgeraldi ) ( Fig. 3G and H View Fig ).
Quadratojugals ( Figs. 1–3 View Fig View Fig View Fig ). These terminal jaw bones are slightly longer in Flectonotus than in Fritziana . Related to the anterior ramus of the pterygoid, a parallel ramus to the quadratojugal, the length of quadratojugal is coincident with the midlength of the anterior ramus of the pterygoid.
Pterygoids. The lengths of the medial and posterior rami are approximately equal in Flectonotus fitzgeraldi ( Fig. 2H View Fig ), whereas the medial ramus is slightly longer than the posterior in Fl. pygmaeus ( Fig. 2G View Fig ). The medial ramus has an acuminate terminus on the otic capsule (Note absence of bilateral symmetry in Fig. 2G View Fig in which one side is acuminate and the other rounded.).
Squamosals. The ventral ramus of the bone has an acuminate terminus ( Fig. 3G and H View Fig ); the ventral end is narrower than the proximal portion at the head of the squamosal. In lateral view, the zygomatic ramus is proportionally longer in Flectonotus than in Fritziana , but it does not articulate with the maxilla.
Mandible. The dentary may be less or more than half the length of the angulosplenial bone ( Fig. 4B View Fig ).
Hyolaryngeal apparatus ( Fig. 4 View Fig ). The alary processes are uniformly slender and extend anterolaterally from the hyoid plate. The posterolateral processes are thin and short, extending for no long than one fifth of posteromedial process of hyoid plate in Flectonotus and one third of posteromedial process of hyoid plate in Fritziana .
Vertebral column ( Fig. 5 View Fig ). Transverse processes II and III are perpendicular to the axial column; TPs IV, V, and VI have a slight posterolateral orientation at an angle between 20 ◦ and 30 ◦, and TP VII is either perpendicular ( Fl. pygmaeus ) or bears a slight posterolateral orientation at an angle between 20 ◦ and 30 ◦ ( Fl. fitzgeraldi ).
Pectoral girdle ( Fig. 6 View Fig ). The cartilaginous omosternum is broader at its anterior end.
Manus ( Fig. 7B View Fig ). The relative lengths of the digits are: III <II <V <IV.
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