Stomiidae
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publication ID |
https://doi.org/10.1093/zoolinnean/zlx090 |
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persistent identifier |
https://treatment.plazi.org/id/1137F67F-FF89-0D3F-FF0C-FB04FB9DFB1C |
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treatment provided by |
Plazi |
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scientific name |
Stomiidae |
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Family Stomiidae View in CoL View at ENA
Canal morphology in representatives of 13 stomiid genera showed considerable variation among taxa. Examination of three whole preserved Astronesthes niger Richardson, 1845 , one A. niger prepared histologically and three µCT reconstructions of A. gemmifer Goode & Bean, 1896 revealed both epithelial canal pores and bony pores, indicating the presence of enclosed and fully ossified SO, PO, MD and IO canals, as well as canals extending caudally from the SO canal (probably OT, PT and ST canals; Table 1). Two longitudinal ridges (inner, outer) extend dorsally from each frontal bone, but never fuse into a single ridge, or meet medially ( Fig. 3E View Figure 3 ). The SO canal begins near the nares, medial to the two bony ridges, and then caudal to the orbit it passes through the outer longitudinal ridge so that it is lateral to both ridges at the canal’s posterior end. Histological material ( A. niger ) confirmed that the SO canal is fully ossified and that SO canal neuromasts vary in diameter (78–128 µm, n = 3). Epithelial canal pores are present in the skin of A. niger at the posterior margin of the skull indicating the presence of one or more canals caudal to the SO canal (the OT, PT and/or ST canals). These canals appear to be enclosed and are either partially or fully ossified, but only some of the canals could be resolved in µCT reconstructions. Bony and epithelial canal pores are visible on the ventral (horizontal) arm of the preoperculum indicating the presence of an enclosed and fully ossified PO canal. The MD canal has an unusually high number of bony and epithelial canal pores and appears to be fully ossified rostrally, but is partially ossified caudally (represented by a trough). A single epithelial canal pore is found ventral to the orbit in whole preserved specimens, indicating the presence of an incompletely ossified IO canal. This was confirmed in histological material ( A. niger ) in which one IO neuromast (~80 µm in diameter) was observed, but the IO canal could not be resolved in µCT reconstructions of A. gemmifer .
Examination of one whole preserved Echiostoma barbatum Lowe, 1843 and µCT reconstructions of three other specimens revealed the presence of epithelial and bony canal pores, respectively ( Table 1). The cranial bones are thin, making them difficult to visualize in µCT reconstructions. Two longitudinal bony ridges (inner, outer) are present in the frontal bone rostral to the orbit and merge into a single ridge medial to the orbits ( Fig. 3E View Figure 3 ). The SO canal begins medial to the ridges at the level of the nares and extends laterally through the bony ridges caudal to the orbit. The SO canal appears to be partially ossified (a trough is present), but is fully enclosed (indicated by the presence of epithelial canal pores) more caudally. A bony trough and epithelial canal pores indicate the presence of fully enclosed and partially ossified canals caudal to the SO canal (probably OT, PT and ST canals). The PO canal appears to be fully ossified in the ventral portion of the preoperculum, but is enclosed and only partially ossified in the dorsal portion of the canal. Bony and epithelial pores along the mandible indicate that the MD canal is enclosed and fully ossified rostrally, and enclosed but incompletely ossified caudally (appearing as a trough, Fig. 4F View Figure 4 ). IO bones could not be resolved in µCT reconstructions, and IO epithelial pores were not visible, indicating the absence of an IO canal.
A µCT reconstruction of one Aristostomias tittmanni Welsh, 1923 revealed SO, MD and PO canals ( Table 1; Figs 4A–E View Figure 4 , 5A View Figure 5 ). A single bony longitudinal ridge is present ( Fig. 3C View Figure 3 ). The SO canal begins rostral to the orbit as a partially ossified canal (a trough in the nasal bone) and is fully ossified medial to the longitudinal ridge. Caudal to the orbit the SO canal extends laterally through the ridge. The canal is narrow, but the canal pores appear to be relatively large compared to those in other taxa ( Fig. 4B View Figure 4 ). A fully ossified PO canal in the form of a hollow tube with pores at either end is found in the preoperculum. An MD canal is indicated by the presence of bony pores in the rostral portion of the mandible and a trough is found more caudally ( Fig. 4E View Figure 4 ) indicating only partial ossification. Neither IO bones nor bony pores were visible in the posterior region of the skull in µCT images, indicating the absence of these canals.
Two µCT reconstructions of Malacosteus niger Ayres, 1848 and Malacosteus sp. revealed several canals that were difficult to differentiate from the surrounding soft tissue ( Table 1; Fig. 5D View Figure 5 ). The SO canal is fully ossified, but µCT 3D reconstructions show that a longitudinal bony ridge is absent ( Fig. 3A View Figure 3 ). Troughs in the preoperculum and in the rostral portion of the dentary indicate the presence of partially ossified PO and MD canals, respectively ( Fig. 5D View Figure 5 ). Neither IO bones nor bony pores in the posterior region of the skull were visible indicating the absence of these canals.
Two µCT reconstructions of Neonesthes capensis (Gilchrist & von Bonde, 1924) and Neonesthes sp. revealed both fully and partially ossified canals, which are narrow with relatively large bony pores, similar to those in Aristostomias ( Table 1; Fig. 5B View Figure 5 ). A longitudinal bony ridge in the frontal bone is absent ( Fig. 3A View Figure 3 ). Bony pores in the frontal and preopercular bones indicate the presence of fully ossified SO and PO canals, respectively. A µCT reconstruction reveals that the MD canal is well ossified rostrally, but is incompletely ossified more caudally, appearing as a trough in the bone. Infraorbital bones could not be resolved in µCT images suggesting the absence of an IO canal. Bony pores and a trough in the bone located caudal to the SO canal suggest the presence of fully and partially ossified canals, respectively, at the posterior margin of the skull.
Three µCT reconstructions of Pachystomias sp. revealed well-ossified narrow canals with small canal pores ( Table 1, Fig. 5C View Figure 5 ). A longitudinal bony ridge extends dorsally along the length of the frontal bone ( Fig. 3C View Figure 3 ). The SO canal starts rostral to the orbit and medial to the bony ridge as an incompletely ossified canal, which is fully ossified rostral to the orbit, but remains medial to the bony ridge along its entire length. The PO canal is fully ossified ventrally, but only partially ossified dorsally (represented by a trough). A trough in the mandible indicates the presence of an incompletely ossified MD canal. Infraorbital bones could not be resolved in µCT images. An ossified canal with two pores is visible caudal to the termination of the SO canal indicating the presence of another canal ( Fig. 5C View Figure 5 ).
A µCT reconstruction of Rhadinesthes decimus (Zugmayer, 1911) revealed thin cranial bones that could not be easily differentiated from surrounding soft tissue. However, 2D cross-sections (as in A. tittmanni , Fig. 4D View Figure 4 ) indicate the presence of several cranial canals ( Table 1). The SO canal appears to be fully ossified, but a longitudinal bony ridge is not present. The PO canal is fully ossified ventrally, but appears to be only partially ossified more dorsally. A fully ossified MD canal is present, but IO, PT, ST or OT canals could not be visualized.
Canal pores in the skin of a whole preserved Bathophilus filifer (Garman, 1899) indicate the presence of SO, PO and MD canals that are enclosed and either partially or fully ossified. An enclosed SO canal starts rostral to the orbit but a longitudinal bony ridge is not present ( Fig. 3A View Figure 3 ). Epithelial canal pores indicate the presence of a canal caudal to the SO canal (probably the OT canal). Epithelial canal pores are visible in the opercular region and on the mandible, indicating the presence of fully enclosed PO and MD canals, respectively. Epithelial canal pores are not present ventral to the orbit suggesting the absence of an IO canal.
Examination of one whole preserved Eustomias hulleyi Gomon & Gibbs, 1985 revealed small epithelial pores indicating the presence of several canals ( Table 1). A longitudinal bony ridge in the frontal bone bifurcates rostral to the orbit, but merges into a single ridge at the level of the orbit ( Fig. 3D View Figure 3 ). An enclosed SO canal is present at the level of the posterior naris, medial to the bifurcated longitudinal ridge and appears to extend laterally through the ridge, terminating caudal to the orbit. An epithelial canal pore caudal to the SO canal suggests the presence of another canal at the posterior margin of the skull (probably the OT canal). Epithelial canal pores are found in the opercular region and on the mandible indicating the presence of enclosed PO and MD canals, respectively. Epithelial canal pores are not present ventral to the orbit suggesting the absence of an IO canal.
One whole preserved Flagellostomias boureei (Zugmayer, 1913) was studied and revealed epithelial canal pores indicating the presence of several enclosed canals ( Table 1). A single bony longitudinal ridge extends dorsally from the frontal bone ( Fig. 3C View Figure 3 ). The SO canal appears to remain medial to the longitudinal ridge along its entire length. Epithelial canal pores caudal to the end of the SO canal suggest the presence of the OT canal. Epithelial canal pores are visible in the opercular region and the rostral portion of the mandible, indicating the presence of enclosed PO and MD canals, respectively. Two canal pores in the epithelium rostral and ventral to the orbit, suggest the presence of an IO canal.
Two whole preserved Idiacanthus antrostomus Gilbert, 1890 have small epithelial canal pores on the head suggesting the presence of enclosed cranial canals that are either partially or fully ossified ( Table 1). A longitudinal bony ridge extends dorsally from the frontal bone ( Figs 3C View Figure 3 , 8C View Figure 8 ). The SO canal begins at the level of the posterior naris, medial to the bony ridge, extends lateral to the bony ridge, and terminates caudal to the orbit. Smaller epithelial canal pores appear to be associated with a canal at the posterior margin of the head, probably the OT canal. Pores are not visible in the opercular region, suggesting the absence of a PO canal. Epithelial canal pores in the rostral portion of the mandible and ventral to the orbit indicate the presence of enclosed MD and IO canals, respectively.
Examination of one whole preserved Opostomias micripnus (Günther, 1878) revealed the presence of epithelial canal pores ( Table 1). Two longitudinal bony ridges (inner and outer) extend dorsally from the frontal bone and extending caudal to the orbit, but they are not fused ( Fig. 3E View Figure 3 ). The fully enclosed SO canal begins rostral to the orbit, sitting medial to both the inner and outer bony ridges. The canal then extends laterally through the inner bony ridge and then through the outer bony ridge, and is found lateral to both ridges before terminating. The SO canal terminates caudal to the orbit. Epithelial canal pores are found caudal to the posterior end of the SO canal indicating the presence of enclosed canals, probably the OT, PT and ST canals. Epithelial canal pores in the opercular region indicate the presence of an enclosed PO canal. A large number of epithelial canal pores along the mandible and three pores ventral to the orbit indicate the presence of enclosed MD and IO canals, respectively.
The study of one whole preserved Tactostoma macropus Bolin, 1939 revealed a single longitudinal bony ridge extending dorsally from the frontal bone ( Fig. 3C View Figure 3 ). The SO canal originates rostral to the anterior naris and medial to the bony ridge and extends laterally through the bony ridge caudal to the orbit. Caudal to the posterior-most SO canal pore, epithelial canal pores indicate the presence of what is probably the OT canal, which appears to be partially ossified. Epithelial canal pores in the opercular region indicate the presence of an enclosed PO canal. A large number of MD pores (ten) are present, extending halfway along the length of the mandible, but the canal continues caudally as an open trough. Two epithelial canal pores rostral and ventral to the orbit indicate the presence of an enclosed IO canal.
SUPERFICIAL NEUROMAST DISTRIBUTIONS
A proliferation of hundreds to thousands of small, round, white, domed structures is found on the head and trunk in A. hemigymnus , in other species of Argyropelecus and in representatives of four other genera of Stomiiformes ( Table 2). These structures were initially observed in whole preserved specimens and their identity as SNs was confirmed with SEM (based on the presence of a kinocilium and multiple stereocilia on the apical surface of each hair cell) and transverse histological sections (showing typical arrangement of hair cell nuclei and more basal support cell nuclei). SN proliferations were indicated in an additional six stomiid genera, for a total of 17 species representing 11 genera in three of the four families of stomiiform fishes. These small SNs are morphologically distinct from the small, complex photophores (light producing organs) that are broadly distributed in these fishes ( Marranzino, 2016).
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