Heterodonty in the New World: An SEM Investigation of Oral Jaw Dentition in the Clingfishes of the Subfamily Gobiesocinae (Teleostei: Gobiesocidae)
New World members of the Gobiesocinae (including Acyrtops, Acyrtus, Arcos, Derilissus, Gobiesox, Pherallodiscus, Rimicola, Sicyases, and Tomicodon) exhibit a heterodont oral dentition comprising two, and in some cases three, different types of teeth. The oral jaw teeth of New World gobiesocines are arranged in a series of 2–4 short staggered rows along the anterolateral margin of the premaxilla and dentary, to which new teeth are added posteriorly (rows 1–4) via shallow open crypts located along the labial margin of the jaw bones and medially (row 1 only) via one or two shallow open crypts located adjacent to the jaw symphysis. A putative monophyletic group comprising solely the New World genera of the Gobiesocinae is hypothesized based on characters of tooth arrangement and replacement in the oral jaws. The phylogenetic position of Eckloniaichthys, a homodont and the only Old World member of the Gobiesocinae, is discussed. The mode of tooth attachment in the Gobiesocidae is Type 2 (i.e., ring of collagen between tooth base and bone of attachment), and the mode of tooth replacement in the oral jaws is interpreted as intermediate between intraosseus and extraosseus replacement (sensu Trapani) and to take place in association with an internal cavity along the jaw bones.
Ventral adhesive disc and mouthparts of Acyrtops beryllinus, a generalized clingfish and member of the Gobiesocinae. (A) Alcohol specimen in oblique ventral (main image) and lateral view (inset) (TCWC 15696.01, 13.0 mm SL). (B) Scanning electron micrograph of head in anterodorsal view (TCWC 15696.07, 12.6 mm SL). (C) Higher magnification image of mouth shown in B.
Scanning electron micrographs of the tooth-bearing oral jaw bones (right side in lateral view; images reversed) in four members of the Gobiesocinae. (A) Acyrtops beryllinus (TCWC 15696.06, 14.0 mm SL). (B) Acyrtus rubiginosus (UF 149202, 20.0 mm SL). (C) Acyrtus lanthanum (UF 212697, 18.0 mm SL). (D) Arcos nudus (ANSP 142945, 27.0 mm SL). Shallow crypts associated with development of replacement teeth outlined by white dashed line. Abbreviations: Co, conical tooth; Ca, caniniform tooth; Den, dentary; In, incisiviform tooth; LF, lateral foramen of premaxilla; MC, opening in mandibular sensory canal; PMax, premaxilla. An “R” used in conjunction with the abbreviations “In” or “Co” identifies a replacement tooth. Subscript numbers (1–4) identify the tooth row to which particular teeth (or an individual tooth) belong. Subscript “m” refers to medial location of certain conical teeth.
Scanning electron micrographs of the oral jaw teeth in Acyrtops beryllinus (TCWC 15696.06, 14.0 mm SL; A–F), Acyrtus rubiginosus (UF 149202, 20.0 mm SL; G–I), Acyrtus lanthanum (UF 212697, 18.0 mm SL; J), and Arcos nudus (ANSP 142945, 27.0 mm SL; K–O). (A) Conical teeth of rows 1–3 on the premaxilla. (B, C) Incisiviform teeth of row 1 on the dentary. (D) Conical teeth of row 2 on the dentary. (E) Conical teeth of row 3 on the dentary. (F) Lingual view of conical teeth in rows 2–3 on dentary. (G) Incisiviform, caniniform, and conical teeth in rows 1–4 on the premaxilla. (H) Incisiviform teeth in row 1 on the dentary. (I) Caniniform teeth in row 2 and conical teeth in row 3 on the dentary. (J) Incisiviform teeth in row 1 on the dentary. (K) Caniniform teeth in row 1 and conical teeth in rows 2–3 on the premaxilla. (L) Conical teeth in rows 2–3 on the premaxilla. (M) Incisiviform teeth in row 1 on the dentary. (N) Developing replacement incisiviform tooth on the dentary. (O) Conical teeth in rows 2–3 on the dentary. Asterisk (*) indicates shallow crypts associated with development of replacement teeth. Abbreviations: Co, conical tooth; Ca, caniniform tooth; In, incisiviform tooth. An “R” used in conjunction with the abbreviations “In” or “Co” identifies a replacement tooth. Subscript numbers (1–4) identify the tooth row to which particular teeth (or an individual tooth) belong. Subscript “m” refers to medial location of certain conical teeth.
Scanning electron micrographs of the tooth-bearing oral jaw bones (right side in lateral view [A, B, D] and lateral and dorsal view [C]; images reversed) in four members of the Gobiesocinae. (A) Derilissus nanus (UF 13372, 12.0 mm SL). (B) Eckloniaichthys scylliorhiniceps (SAIAB 36245, 24.0 mm SL). (C) Gobiesox maeandricus (VIMS 25269, 60.0 mm SL). (D) Gobiesox strumosus (TCWC 16453.02, 19.3 mm SL). Shallow crypts associated with development of replacement teeth outlined by white dashed line. Abbreviations: Co, conical tooth; Ca, caniniform tooth; Den, dentary; In, incisiviform tooth; LF, lateral foramen of premaxilla; MC, opening in mandibular sensory canal; PMax, premaxilla. An “R” used in conjunction with the abbreviations “In” or “Co” identifies a replacement tooth. Subscript numbers (1–4) identify the tooth row to which particular teeth (or an individual tooth) belong. Subscript “m” refers to medial location of certain conical teeth.
Scanning electron micrographs of the oral jaw teeth in Derilissus nanus (UF 13372, 12.0 mm SL; A–D), Derilissus kremnobates (UF 224469, 17.1 mm SL; E), Eckloniaichthys scylliorhiniceps (SAIAB 36245, 24.0 mm SL; F–H), Gobiesox strumosus (TCWC 16453.02, 19.3 mm SL; I–J), and Gobiesox maeandricus (VIMS 25269, 60.0 mm SL; K–O). (A) Incisiviform and conical teeth in row 1 on the premaxilla. (B) Incisiviform teeth in row 1 on the dentary. (C) Incisiviform and conical teeth in rows 1–2 on the dentary. (D) Conical teeth in rows 2–3 on the dentary. (E) Incisiviform teeth in row 1 on the dentary. (F) Incisiviform teeth on the premaxilla. (G) Incisiviform teeth on the dentary. (H) Close-up of the cusp of a single incisiviform tooth on the dentary. (I) Conical teeth in rows 1–3 on the premaxilla. (J) Incisiviform teeth in row 1 on the dentary. (K) Developing replacement incisiviform teeth on the dentary. (L) Conical teeth in rows 3–4 on the dentary. (M) Conical teeth on the anterolingual face of the dentary. (N) Conical teeth in rows 1–3 on the premaxilla. (O) Incisiviform teeth in row 1 on the dentary. Asterisk (*) indicates shallow crypts associated with development of replacement teeth. Abbreviations: Co, conical; Ca, caniniform; In, incisiviform. An “R” used in conjunction with the abbreviations “In” or “Co” identifies a replacement tooth. Subscript numbers (1–4) identify the tooth row to which particular teeth (or an individual tooth) belong. Subscript “m” refers to medial location of certain conical teeth.
Photographs and schematic line drawings of the upper jaw dentition (right side) in cleared-and-stained specimens of successively larger, hence inferred older, individuals of Gobiesox strumosus to highlight aspects of tooth development. (A, B) TCWC 303.07, 14.7 mm SL. (C, D) TCWC 16453.02, 25.0 mm SL. (E, F) TCWC 2594.01, 33.0 mm SL. (G, H) TCWC 520.01, 52.5 mm SL. Images in left column show the right side in lateral view (image reversed, anterior to left). Images in right column show the right side in ventral view (anterior to top). Ovals and circles in line drawings represent teeth, with those along the anterolateral margin illustrated in different shades of gray to indicate membership of rows 1–4. Ovals or circles with a black dot at the center represent replacement teeth (in various stages of development). Arrows indicate location of replacement teeth in corresponding photographs. Small conical teeth located across anterolingual surface of the premaxilla that cannot be assigned to individual rows are not shaded. Abbreviation: RCo, replacement conical tooth. Subscript numbers (1–4) identify the tooth row to which replacement teeth belong. An asterisk indicates position of a dislodged replacement tooth in A, B, E, and F.
Photographs of the lower jaw dentition adjacent to the symphysis (right side, images reversed) in cleared-and-stained specimens of successively larger, hence inferred older, individuals of Gobiesox strumosus to highlight aspects of tooth development and replacement. (A) TCWC 303.07, 14.7 mm SL. (B) TCWC 16453.02, 25.0 mm SL. (C) TCWC 2594.01, 33.0 mm SL. (D) TCWC 520.01, 52.5 mm SL. Abbreviations: AB, developing attachment bone; Co, conical tooth; In, incisiviform tooth; MC, opening in mandibular sensory canal. An “R” used in conjunction with the abbreviations “In” or “Co” identifies a replacement tooth. Subscript numbers (1–3) identify the tooth row to which particular teeth (or an individual tooth) belong. Asterisks (*) indicate location of shallow tooth crypts. Developing replacement tooth highlighted with black outline in A. Developing replacement tooth dislodged from crypt in B.
Sections through the premaxilla and dentary of Gobiesox strumosus (TCWC 16453.02, 22.5 mm SL) showing association between teeth and cavity at center of bone of attachment. (A) Transverse section through premaxilla and dentary. (B, C) Sagittal sections through dentary. Abbreviations: Cav, cavity; Den, dentary; FT, functional tooth; GE, gum epithelium; LL, lower lip; PC, pulp cavity; PMax, premaxilla; TG, replacement tooth germ.
Lateral views of the tooth-bearing oral jaw bones of the right side (images reversed) in four members of the Gobiesocinae. (A) Pherallodiscus funebris (AMNH 5557, 37.5 mm SL). (B) Rimicola muscarum (SIO 69-248, male, 32.5 mm SL, and female, 27.8 mm SL). (C) Sicyases sanguineus (USNM 213846, 19.0 mm SL). (D) Tomicodon zebra (MCZ 45664, 35.0 mm SL). Shallow crypts associated with development of replacement teeth outlined by white dashed line. Abbreviations: Co, conical teeth; Ca, caniniform teeth; Den, dentary; In, incisiviform teeth; LF, lateral foramen of premaxilla; MC, opening in mandibular sensory canal; PMax, premaxilla. An “R” used in conjunction with the abbreviations “In” or “Co” identifies a replacement tooth. Subscript numbers (1–4) identify the tooth row to which particular teeth (or an individual tooth) belong. Subscript “m” refers to medial location of certain conical teeth.
Scanning electron micrographs of the oral jaw teeth in Pherallodiscus funebris (AMNH 5557, 37.5 mm SL; A–C), Rimicola muscarum (SIO 69-248, male, 32.5 mm SL, and female, 27.8 mm SL; D–H), Sicyases sanguineus (USNM 213846, 19.0 mm SL; I–K), and Tomicodon zebra (MCZ 45664, 35.0 mm SL; L–N). (A) Conical teeth in rows 2–3 on the premaxilla. (B) Incisiviform teeth in row 1 on the dentary. (C) Conical teeth in rows 2–4 on the dentary. (D) Conical teeth in rows 2–3 on the premaxilla. (E) Conical and incisiviform teeth in row 1 on the dentary in female. (F) Developing replacement caniniform tooth in row 2 on the dentary in male. (G) Conical and incisiviform teeth in row 1 on the dentary in male. (H) lingual view of conical and incisiviform teeth in row 1 on the dentary in male. (I) Incisiviform teeth in row 1 on the premaxilla. (J) Incisiviform teeth in row 1 on the dentary. (K) Conical teeth in row 2 on the dentary. (L) Incisiviform teeth in row 1 on the dentary. (M) Developing replacement incisiviform tooth on the dentary. (N) Caniniform tooth on dentary. Asterisk (*) indicates shallow crypts associated with development of replacement teeth. Abbreviations: Co, conical teeth; Ca, caniniform teeth; In, incisiviform teeth. An “R” used in conjunction with the abbreviation “In” identifies a replacement tooth. Subscript numbers (1–4) identify the tooth row to which particular teeth (or an individual tooth) belong. Subscript “m” refers to medial location of certain conical teeth.
Scanning electron micrographs of the tooth-bearing oral jaws and oral jaw teeth in Lepadogaster lepadogaster (TCWC 16777.01, 43.4 mm SL; A, C–E), Lepadichthys lineatus (SAIAB 9319, 23.5 mm SL; B, H–J), and Gouania wildenowi (TCWC 16777.03, 44.0 mm SL; F, G). (A, B) Premaxilla and dentary, right side in lateral view (image reversed). (C) Patch of conical teeth on lingual surface of premaxilla. (D) Conical teeth along lateral margin of premaxilla. (E) Patch of conical teeth on lingual surface of dentary. (F) Patch of conical teeth on lingual surface of premaxilla. (G) Dentary, right side in slight dorsolingual view (image reversed). (H) Incisiviform teeth on the premaxilla. (I) Close-up of the cusp of a single incisiviform tooth on the premaxilla. (J) Incisiviform teeth on the dentary. Shallow crypts associated with development of replacement teeth outlined by white dashed line in A, B. Asterisk (*) indicates shallow crypts associated with development of replacement teeth. Abbreviations: Den, dentary; PMax, premaxilla.
Tooth-bearing oral jaw bones of Lepadogaster lepadogaster. (A) Photograph and schematic line drawing of the premaxilla (ventral view) and dentary (dorso-medial view; TCWC 16777.01, 43.4 mm SL). Fully attached and developing teeth are shaded in light or dark gray, respectively. Asterisks (*) indicate location of dislodged developing replacement teeth. Sections through premaxilla (B) and dentary (C) (TCWC 16778.01, 17.0 mm SL) showing association between developing replacement teeth and cavity at center of bone of attachment. Abbreviations: Cav, cavity; Den, dentary; GE, gum epithelium; LL, lower lip; PC, pulp cavity; PMax, premaxilla; TG, replacement tooth germ. Circles in B and C highlight location of vascular tissue in cavity.
Volume renderings of the MicroCT scan data showing the cranium (anterior to front) in three New World gobiesocines and the lepadogastrine Diplecogaster bimaculata. Images on the right are colored to convey density of different cranial structures. (A) Arcos nudus, ANSP 115602, 50.0 mm SL. (B) Gobiesox strumosus, TCWC 11200.20, 48.0 mm SL. (C) Tomicodon fasciatus, UF 212582, 30.2 mm SL. (D) Diplecogaster bimaculata, ROM 41585, 38.0 mm SL. Cold and warm colors represent low and high densities, respectively, in right images. Images not to scale.
Contributor Notes
Associate Editor: G. Arratia.