Cannibalistic morph determinations were initially made in the field based on visual observations of the presence of hypertrophied vomerine
teeth; typical morph individuals had much smaller, peg-like, teeth (Pedersen, 1991; Fig.
Jaws about equal, oblique, premaxilla with an abrupt bend between the anterior horizontal portion and lateral part; maxilla ends below about anterior edge of pupil; maxillary length 2.9 (2.9-3.3) in HL; lips thin; teeth conical with slightly curved tips, extending on to outer surface of lips; teeth of upper jaw in 6-9 irregular rows anteriorly, reduced to 1-2 rows posteriorly, where they are exposed when mouth is closed; teeth in lower jaw in about 6-8 irregular rows anteriorly, reduced to 1-2 rows posteriorly; vomerine
teeth poorly developed, holotype with a few scattered teeth in narrow band; palatine teeth absent.
The relative shape of the vomerine
tooth patch is typically cited as the sole reliable criterion (Claro and Lindeman, 2008).
tooth patch is situated anteriorly in the roof of the mouth.
tooth patch triangular-shaped, without a median posterior extension, and sparsely covered with small teeth.
Vomerivulus Fowler, 1944 was proposed as a new monotypic subgenus of Rivulus based on the possession of vomerine
teeth in its type species, R.
Dentition well developed, 2 tooth rows anteriorly in both jaws, outer row teeth at symphysis long and 2 stout conical vomerine
oblongus: "Cranium thick and heavy; interorbital space and occiput flat or slightly convex, the former about 3.7 times in base of cranium; postocular, tympanic and parietal spines present, directed backward and downward; preocular supraocular, coronal and nuchal spines entirely absent; parietal ridges low but broad; supraocular edges depressed, never higher than the frontal ridges; frontal ridges low, the space between them flattish, never deeply concave; mesethmoid processes directed forward and upward; parietals meeting or narrowly separated; the patch of vomerine
teeth triangular; base of cranium straight; ventral process of basisphenoid meeting the parasphenoid.
Specifically, as illustrated in Lannoo and Bachmann (1984), larvae were scored as cannibals based on their enlarged vomerine
ridge and elongate teeth (see also Pfennig et al.
Cannibals are recognized by their broad heads and enlarged vomerine
teeth (Pedersen 1991; Collins et al.
Vocal slits large, extending from beneath postero-lateral margin of tongue to near jaw angle; tongue with a shallow posterior notch; vomerine
teeth in two well-separated, transverse rows between posterior halves of obliquely elliptical choanae.
teeth absent, anterior border of vomer thickened.
exophthalmus could be confused with Tepuihyla talbergae, from which it differs in possessing large and bulgy eyes, more vomerine
teeth (21 vs.
Cannibal morph phenotypes were determined by a qualitative assessment of head shape, head width and vomerine