The Lateral Line System in the Nurseryfish Kurtus gulliveri (Percomorpha: Kurtidae): A Distribution and Innervation of Superficial Neuromasts Unique within Percomorphs
The lateral line system and its innervation were examined in the Nurseryfish Kurtus gulliveri (family Kurtidae). The system is characterized by ca. 373,000 superficial neuromasts (SNs; at 152 mm standard length) occurring over one side of the entire body surface, including the dorsal, anal, and caudal fins. A fine-grid pattern of SNs is spread regularly over the surface, comprising many longitudinal and transverse SN rows, with the axis of best physiological sensibility perpendicular to the long axis of the neuromasts. On the head, rami of the anterior lateral line nerve are similar to those in typical percomorphs, each innervating numerous SNs by extensive ramification. On the trunk, 22 elongated dorsal ramules of the lateral ramus (of the posterior lateral line nerve) supply SNs on the dorsal half of the trunk and dorsal fin, and the dorsal longitudinal collector nerve innervates 22 canal neuromasts along the short (incomplete) trunk lateral line canal. Sixteen ventral ramules arise from the lateral ramus to supply SNs on the ventral half of the trunk and anal fin, which is similar to the pattern of the dorsal ramules. Innervation of the trunk and fins is distinctive, differing from all percomorphs known thus far.
Lateral line canals and canal neuromasts on the head of Kurtus gulliveri (NSMT-P 92054, 152 mm SL, female). (A) Dorsal, (B) lateral, and (C) ventral views. Gray = Canals; dark gray = pore openings; large dark blue dots = canal neuromasts. Abbreviations: IOC, infraorbital canal; MDC, mandibular canal; OTC, otic canal; POC, post-otic canal; PRC, preopercular canal; SOC, supraorbital canal; STC, supratemporal canal; TP(TRC), temporal portion of trunk canal.
Superficial neuromasts (SNs) of Kurtus gulliveri. (A) Gray area indicates overall SN distribution; b–j correspond to areas shown in (B)–(J). (B–J) SNs stained with Cyanine Blue on the dorsolateral surface of the head (B, C), cheek (D), lower jaw (E), around the trunk canal (F), trunk (G), and dorsal (H), anal (I), and caudal (J) fins. Arrowheads indicate SNs (note not all SNs indicated). Abbreviations: af, anal-fin ray; cf, caudal-fin ray; df, dorsal-fin ray; IOC, infraorbital canal; ll, lower lip; OT, otic canal; po, pore opening; TRC, trunk canal. Specimens: (B, F, H, I) NSMT-P 129785, 158 mm SL, male; (C) NSMT-P 92054, 110 mm SL, female; (D, E) NSMT-P 129784, 143 mm SL, male; (G) NSMT-P 92054, 128 mm SL, male; (J) NSMT-P 92054, 167 mm SL, male.
Scales on the trunk and superficial neuromasts (SNs) of Kurtus gulliveri (NSMT-P 92054, 167 mm SL, male; right side, reversed). Dashed lines indicate posterior margins of scales. Arrowheads indicate SNs (blue dots) stained with Cyanine Blue.
SEM image of superficial neuromasts (SNs) on the cheek (A, B, E, F) and trunk (C, D, G) of Kurtus gulliveri (NSMT-P 129785). Diagrams of SN pattern (H) and microstructure (I) of an SN (based on the cheek of NSMT-P 129785). Blue arrowheads = SNs with longitudinal sensory strip (i.e., longitudinal sensory orientation), arranged as transverse rows; orange arrowheads = SNs with transverse sensory strip (i.e., transverse sensory orientation), arranged as longitudinal rows. Double-headed arrows = long axes of sensory strips (i.e., sensory orientations). (E) An SN with a longitudinal sensory strip. (F) An SN with a transverse sensory strip. (G) Sensory bundles on an SN. (H) SN pattern comprising longitudinal rows (each SN with transverse sensory strip; blue) and transverse rows (with longitudinal sensory strip; orange); SNs are depicted slightly larger than actual size. (I) SN with transverse sensory strip (i.e., transverse sensory orientation); orange dashed line indicates the outline of the sensory strip; orange-filled circles indicate sensory bundles, each of which consists of a kinocilium (black dot) and a bundle of stereocilia (orange region). Abbreviations: Aa, acute angle; Ba, broad angle; Ki, kinocilium; Sb, sensory bundles; St, a bundle of stereocilia.
Innervation of lateral line system on the head of Kurtus gulliveri (NSMT-P 129783, 107 mm SL, female). (A) Dorsal and (B) lateral views. Dark blue dots = canal neuromasts. Abbreviations: BR, buccal ramus = green; MDR, mandibular ramus = yellow; MDRm, middle ramule of mandibular ramus; MDRp, posterior ramule of mandibular ramus; MDRpa, anterior element of MDRp; OR, otic ramus = beige; SOR, superficial ophthalmic ramus = blue; STR, supratemporal ramus = red.
Lateral line system and its innervation on the trunk and dorsal, anal, and caudal fins of Kurtus gulliveri (NSMT-P 129783, 107 mm SL, female). Dark blue dots = canal neuromasts. Abbreviations: CN, canal neuromast; DLCN, dorsal longitudinal collector nerve; DR, dorsal ramule; DR1a, anterior element of DR1; DR1b, middle element of DR1; DR1c, posterior element of DR1; LR, lateral ramus; STC, supratemporal canal; TRC, trunk canal; Type I, Type I branch; VR, ventral ramule.
Innervation of canal and superficial neuromasts on the trunk of Kurtus gulliveri (NSMT-P 129784, 143 mm SL, male). Arrows indicate continuation of nerve courses. Large blue dots = canal neuromasts; small gray dots = superficial neuromasts. Abbreviations: CN, canal neuromast; DLCN, dorsal longitudinal collector nerve; DR, dorsal ramule; LLS, lateral line scale; po, pore opening; TRC, trunk canal; Type I, Type I branch.