Gonostomatidae

Family Gonostomatidae View in CoL View at ENA

Hundreds of small, round, white, domed structures (~30–40 µm in diameter) were interpreted to be SNs and stand out against the darkly pigmented skin of the head and elongated trunk of G. elongatum ( Fig. 8B, D View Figure 8 ). They occur on the head and in vertical lines that run around the circumference of the trunk between large photophores in each body segment. In a small individual (50-mm SL), ~500 SNs are present on one side of the head and more than 500 are present on one side of the trunk. In some cases, SNs are located between depressions in a linear series ( Fig. 8E View Figure 8 ), supporting the interpretation that the depressions are actually the locations of SNs that had been damaged and lost. Accounting for these missing SNs, it is likely that there are more than 1200 SNs on one side of the body in one specimen of G. elongatum .

Examination of specimens of five species of Cyclothone that had an intact epidermis ( C. acclinidens , C. braueri , C. microdon , C. pseudopallida , C. signata ), revealed numerous, small, round, domed was obtained by studying several specimens of C. microdon , which revealed more than 530 SNs on one side of the head and trunk ( Table 2).

Figure 6. Superficial neuromast distribution in Argyropelecus spp. Distribution of SNs in (A) A. affinis , (B) A. aculeatus (based on 11 fish) and (C) A. hemigymnus (based on five fish), drawn from whole preserved specimens. Outlines from Baird (1971). Blue, superficial neuromasts; red, canal neuromasts. Neuromasts are enlarged to enhance visibility.

structures (SNs; ~55–80 µm in diameter) on the head and trunk. They are found in lines and clusters in similar locations on the head and trunk and on the pectoral, pelvic and caudal fins ( Fig. 8A View Figure 8 ) in all species. Histology ( C. microdon ) confirmed their identity as SNs, but SEM ( C. signata ) revealed only a few SNs in which the sensory hair cells could be visualized. An examination of four whole preserved C. microdon revealed several hundred SNs on one side of the head and trunk in a single specimen. Due to variation in specimen condition, a more complete assessment of neuromast distribution