The Lateral Line System in Anuran Tadpoles: Neuromast Morphology, Arrangement, and Innervation

Abstract

Anuran larvae have been classified into four morphological types which reflect intraordinal macroevolution. At present, complete characterizations of the lateral line system are only available for Xenopus laevis (Type I) and Discoglossus pictus (Type III). We analyzed the morphology, arrangement, and innervation of neuromasts related to the anterodorsal and anteroventral lateral line nerves in 10 anuran species representing Types I, II, and IV with the aim of interpreting the existing variation and discussing the evolution of the lateral line in anuran larvae. We found: (1) the presence of two orbital and three mandibular neuromast lines in all anuran larvae studied, (2) the ventral arrangement of mandibular neuromast lines appears to have evolved convergently in Larval Types I and II, and the lateroventral arrangement of mandibular lines of neuromasts appears to have evolved in Larval Types III and IV; (3) interspecific variation in the organization, size, and number of sensory cells per neuromast within the lines; and (4) the supralabial extension of the Angular line in Lepidobatrachus spp. and the tentacular location of the Oral neuromasts in X. laevis are concomitant with their particular morphologies. Based on the variation described we find that the lateral line system in anuran larvae seems to have been maintained without significant changes, with the exception of Lepidobatrachus spp. and Xenopus. These unique features added to other of Lepidobatrachus tadpoles are sufficient to propose a new Larval Type (V). Anat Rec, 297:1508Rec, 297: -1522Rec, 297: , 2014. V C 2014 Wiley Periodicals, Inc.

Variability of Rheotaxis Behaviors in Larval Bullfrogs Highlights Species Diversity in Lateral Line Function

“…A primary difference is in the morphology of the lateral line neuromasts [4, 5]. Lannoo [4] described neuromasts of bullfrog tadpoles as small (containing less than 15 hair cells), and arranged in linear stitches with fewer than five neuromasts.…”

“…Unlike in fishes, in anurans the lateral line sensors, neuromasts, are not easily divided into superficial and canal types [3]. Neuromasts vary considerably in their number, size, and organization between tadpoles classified into four different ecomorphological types [4,5]. How ecological and morphological differences translate into behavioral differences in lateral line function has not been fully explored.…”

The ontogeny of the lateral line system in Telmatobius atacamensis (Anura, Telmatobiidae)

“…Innervation of the lateral lines was analyzed from whole‐mount preparations stained for peripheral nerves with Sudan Black B, following the procedures described by Filipski and Wilson () and Nishikawa (). I used the terminology of Quinzio and Fabrezi (, ) to describe the lateral lines. For cranial and lateral line nerves, we applied the terminology provided by Schlosser and Roth () for Discoglossus pictus , with some modifications taken from Quinzio and Fabrezi (, ).…”

“…(Escher, ), Occidozyga laevis (Wright, ), O . lima (Fritzsch et al, ) and Lepidobatrachus laevis (Fritzsch et al, ; Quinzio & Fabrezi, , ).…”

“…The topography of the larval mechanosensory receptors shows interspecific variation in the arrangement, extension, and relationship among the lateral lines of neuromasts of about 70 species (e.g., Lannoo, 1987; Hall, Larsen & Fitzner, ; Fabrezi & Quinzio, ; Fabrezi, Quinzio, & Goldberg, ; Fabrezi, Quinzio, Goldberg & De Sá, ; Quinzio & Fabrezi, ). These studies have allowed us to characterize the topography of the lateral lines into distinct patterns (Quinzio & Fabrezi, ) that correspond to the larval types established by Orton ().…”