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Revision of so-called Pomatoschistus (Gobiiformes, Teleostei) from the late Eocene and early Oligocene

Christoph Gierl and Bettina Reichenbacher

Plain Language Abstract

Gobiiformes (or 'gobies') belong to the most diverse groups among vertebrates, and are found in both freshwater and marine habitats. However, it is often difficult to distinguish between morphologically similar forms. Moreover, species identification is based mostly on soft-tissue features, such as the pattern of sensory pores on the head, which makes fossil classification extremely challenging. Pomatoschistus bleicheri (Sauvage) from the lower Oligocene (~30 Ma old) of Rouffach (France) and Pomatoschistus(?) cf. bleicheri (Sauvage) from the upper Eocene (~35 Ma old) of the Isle of Wight (England) epitomize this problem. They are of special interest because they are regarded as the oldest fossil representatives of the more advanced gobies (Gobiidae + Oxudercidae). Here, we show that these fossils do not belong to the genus Pomatoschistus or indeed to the Gobiidae + Oxudercidae, nor can they be accommodated in any existing family of the "basal gobiiforms." Instead, the fossils from Rouffach and the Isle of Wight can both be placed in the same extinct genus, †Paralates Sauvage. Furthermore, differences in the shape of the frontal bones (on the forehead) and numbers of caudal fin rays lead to the conclusion that the material from Rouffach corresponds to †Paralates bleicheri Sauvage, while that from the Isle of Wight is assigned to a new species, which we name †Paralates chapelcorneri n. sp. Therefore, the oldest known fossil representative of the modern gobies remains †Gobius jarosi Přikryl and Reichenbacher, 2017 from the lower Miocene (20.4 Ma-19.1 Ma old) of Moravia (Czech Republic).

Resumen en Español

Revisión de los llamados Pomatoschistus (Gobiiformes, Teleostei) del Eoceno tardío y Oligoceno temprano

Los Gobiiformes (Teleostei) están entre los grupos más ricos en especies entre los vertebrados, y se encuentran en todos los hábitats acuáticos. La identificación de las especies actuales de Gobiiformes se basa principalmente en caracteres de los tejidos blandos, y su diversidad y variabilidad fenotípica a menudo hace que la determinación de las especies sea difícil. Los fósiles carecen normalmente de características de los tejidos blandos y la asignación segura de Gobiiformes fósiles a nivel de familia y género puede ser extremadamente problemática. "Pomatoschistus bleicheri (Sauvage)" del Oligoceno inferior de Rouffach (Francia) y "Pomatoschistus (?) cf. bleicheri (Sauvage)" del Eoceno superior de la Isla de Wight (Inglaterra) ejemplifican estas dificultades. Estos hallazgos son de especial interés, ya que pueden representar los miembros más antiguos, basados en el esqueleto fósil, de los Gobiidae + Oxudercidae (Gobiiformes con cinco branquiostegales, en adelante 5brG). El nuevo examen del material tipo de estas dos especies revela ahora la presencia de una premaxila con un proceso postmaxilar, lo que impide la asignación de estos fósiles al género Pomatoschistus. De hecho, ni siquiera pertenecen al grupo 5brG porque muestran seis branquiostegales. Concluimos que tanto los fósiles de Francia como los de Inglaterra pertenecen a †Paralates Sauvage. Las diferencias en la forma de los huesos frontales y el número de radios de la aleta caudal nos permiten asignar el material francés a †Pa. bleicheri Sauvage y los ejemplares ingleses a †Pa. chapelcorneri n. sp. Así, la especie 5brG más antigua conocida actualmente, basada en esqueletos articulados, es †Gobius jarosi Přikryl et Reichenbacher, 2017 del Mioceno inferior.

Palabras clave: Gobiiformes fósiles; nueva especie; Gobiidae; Oxudercidae; branquiostegales

Traducción: Enrique Peñalver (Sociedad Española de Paleontología)

Résumé en Français

text

Translator: Antoine Souron

Deutsche Zusammenfassung

In progress

Translator: Eva Gebauer

Arabic

721 arab

Translator: Ashraf M.T. Elewa

 

 

FIGURE 1. Phylogeny of the Gobiiformes according to Thacker et al. (2015) and Nelson et al. (2016). 6brG = gobiiforms with six branchiostegal rays, 5brG = gobiiforms with five branchiostegal rays.

figure1 

FIGURE 2.Paralates bleicheri Sauvage, 1883. 1. NMB Ruf. 13_1 skull. 2. NMB Ruf. 15b (Neotype, designated by Gaudant, 1979). 3. NMB Ruf. 15a. Abbreviations: chy = ceratohyal, d = dentary, f = frontal, mx = maxilla, meth = mesethmoid, op = opercle, pmx = premaxilla, pop = preopercle, q = quadrate, sop = subopercle. (Photos by M. Schellenberger.)

 figure2

FIGURE 3. Comparison of frontals (highlighted by the black lines). 1.Paralates bleicheri Sauvage, 1883, NMB Ruf. 13_1 skull mirrored. (Photo by M. Schellenberger.) 2.Paralates chapelcorneri n. sp., NHMUK PV P 59786. Same scale for both skulls.

figure3 

FIGURE 4.Paralates bleicheri Sauvage, 1883, NMB Ruf. 18. 1. Viewed under normal light. (Photo by M. Schellenberger.) 2. Imaged with UV light (Photo by H. Tischlinger).

figure4 

FIGURE 5.Paralates chapelcorneri n. sp., NHMUK PV P 59786. 1. Skull. 2. Complete specimen. 3. Detail of opercle with cycloid scales. Abbreviations: art = anguloarticular, d = dentary, ect = ectopterygoid, f = frontal, meth = mesethmoid, mx = maxilla, op = opercle, pmx = premaxilla, pop = preopercle, q = quadrate, scl = supracleithrum.

figure5 

FIGURE 6.Paralates chapelcorneri n. sp., NHMUK PV P 59785. 1. Complete specimen. 2. Region of the first dorsal fin. Arrows point from the pterygiophores to the interneural spaces into which each inserts. Pterygiophore formula = 3-2121100 The spinous rays of the first dorsal fin are marked with roman numerals. Abbreviations: 1-7 = pterygiophores, ptm = post-temporal, ns-v3-10 = neural spines of vertebrae 3-10, v2-4 = vertebral centra 2-4.

 figure6

FIGURE 7.Paralates chapelcorneri n. sp., NHMUK PV P59785_counterpart. 1. Complete specimen. 2. Caudal skeleton and fin. Small Roman numerals in parentheses label unbranched, unsegmented rays, small Roman numerals indicate segmented unbranched rays, and Arabic numerals designate segmented, branched rays (after Fricke, 1983). Abbreviations: epu = epural, hpu = hemal spine of preural centrum, hy = hypural, npu = neural spine of preural centrum, phy = parhypural, pu = preural centrum, us = urostyle.

 figure7

FIGURE 8.Paralates chapelcorneri n. sp., NHMUK PV P 59784. 1. Complete specimen. 2. Skull showing possible symplectic and six branchiostegals. Abbreviations: 1-6 = branchiostegals, ect = ectopterygoid, mpt = metapterygoid, sf = suspensorium fenestra, sym = symplectic. (Photos by K. Webb; © The Trustees of the Natural History Museum, London)

 figure8

 

 

TABLE 1. Meristic counts of all studied specimens of †Paralates . Numbers not in bold are subject to some uncertainty.

  Oligocene of Rouffach, no. Ruf Upper Eocene of Isle of Wight
(Chapelcorner Fish Bed)
Specimen # 6a/b 9_1 9_2 11/13_2 15a/b 18 P 59784 P 59785 P 59786 C 23632 C 23633
First dorsal fin (D1) - - >V - VII VII VII VII VII - -
Second dorsal fin (D2) I,10 I,9 I,9 I,9 I,8 I,10 I,9 I,10 >7 - -
Anal fin (A) 10 >8 10 >7 I,8 I,8 I,8 I,9 - - -
C (branched, segmented) 12 13 ? 13 12 12 12 13 - - -
C (unbranched, segmented)             2 + 1 or 2 2 + 2      
C (unbranched, unsegmented)           7 10 + ? 10 + 12      
Ventral fin (V) - - - - I,5 - I,5 I,5 - - -
Pectoral fin (P) - >11 14 >9 12 - >14 16 >11 >13 >9
Vertebrae [postabdominal vert.] >23 [17] >21 [16] >27 >23 [17] 29 [17] 30 [18] 30 [18] 31
[19]
>23 >11 29 [17]
Pterygiophore formula D1 - - - - - - - 3-2121100 - - -

 

 

TABLE 2. Morphometrics of the genus †Paralates in mm. Values standardized to standard length are given in brackets. Abbreviations: A = anal fin, C = caudal fin, D1 = first dorsal fin, D2 = second dorsal fin, D2C = distance between end of D2 and first procurrent ray of C, P = pectoral fin, V = pelvic fin.

# Ruf. 11/13_2 Ruf. 15a/b Ruf. 18 P 59784 P 59785 P 59786
Total length 29.1 (115%) 29.5 (118%) 34.5 (119%) 35.3 (116%) 22.5 (116%) >22.3
Standard length 25.2 25.1 29.1 30.4 19.4 >22.3
Max body height 5.4 (21.4%) 5.4 (21.5%) 5.5 (18.9%) 5.9 (19.4%) 4.4 (22.7%) -
Head length 9.4 (37.3%) 6.9 (27.5%) 7.1 (24.4%) 9.5 (31.3%) 5.6 (28.9%) 6.6
Head height 6.6 (26.1%) 5.4 (21.5%) 5.2 (17.9%) 6.9 (22.7%) 4.9 (25.3%) -
Horizontal eye diameter 1.5 (5.9%) 1.2 (4.8%) 1.3 (4.5%) - 1.7 (8.8%) 1.4
Dist snout to D1 11.7 (46.4%) 9.2 (36.7%) 10.8 (37.1%) 11.7 (38.5%) 7.8 (40.2%) 7.9
Dist snout to D2 14.6 (57.9%) 14.5 (57.8%) 16.2 (55.7%) 17.4 (57.2%) 11.2 (57.7%) 12.8
Dist snout to A 15.8 (62.7%) 15.7 (62.5%) 16.5 (56.7%) 18.1 (59.5%) 11.5 (59,3%) 13.3
Dist snout to P 9.4 (37,3%) 8.7 (34.7%) - 10.7 (35.2%) 6.8 (35.1%) 7.4
Dist snout to V 9.2 (36.5%) 8.2 (32.7%) - 10.6 (34.9%) 6.6 (34.0%) -
Length D1 >2.1 >2.4 >2.4 >3.4 >1.7 -
Length D2 2.8 (11.1%) >2.4 4.4 (15.1%) >4.3 >3.1 -
Length A 2.6 (10.3%) >2.4 >2.3 >3.5 >2.9 -
Length P >0.8 >1.3 - >1.9 >0.8 >2.8
Length V >1.2 >1.5 - >2.7 2.7 (13.9%) -
Base length D1 >0.6 2.3 (9.2%) 2.3 (7.9%) 2.6 (8.6%) 1.6 (8.2%) -
Base length D2 3.1 (12.3%) 3.0 (12.0%) 4.0 (13.7%) >3.5 2.4 (12.4%) -
Base length A 3.0 (11.9%) 2.5 (19.0%) 3.7 (12.7%) 3.6 (11.8%) 1.9 (9.8%) -
Length caudal peduncle 6.3 (25.0%) 6.8 (27.1%) 8.9 (30.6%) 8.3 (27.3%) 5.7 (29.4%) -
D2C 6.7 (26.6%) 7.3 (29.1%) 8.4 (28.6%) 7.5 (24.7%) 5.0 (25.8%) -
Min height of caud ped 2.0 (7.9%) 1.7 (6.8%) 2.6 (8.9%) 3.0( 9.7%) 2.2 (11.3%) -
Length of caudal fin 3.8 (15.1%) >3.8 >5.0 5.4 (17.8%) 3.6 (18.6%) -
Length of vertebrae 0.5-0.6 (1.9-2.3%) 0.6-0.7 (2.4-2.8%) 0.6-0.8 (2.1-2.7%) 0.5-0.7 (1.6-2.3%) 0.4-0.5 (2.1-2.6%) 0.4-0.5

 

TABLE 3. Meristic characters of recent gobioid taxa for which the pterygiophore formula 3-212110(0) has been observed in at least one species of the genus. The number of caudal fin rays refers to all segmented rays (branched and unbranched). Abbreviations: A = anal fin, C = caudal fin, D1 = first dorsal fin, D2 = second dorsal fin, P = pectoral fin, V = pelvic fin.

Taxon D1 D2 A C V P Vertebrae [postabd] Source Family
Paralates bleicheri Sauvage, 1883 VII I,10 I,9 >12-13 I,5 14 29
[17-18?]
this study inc. sed.
Paralates chapelcorneri n. sp. VII I,10 I,8-9 14-17 I,5 14-16 30?-31 [18?-19] this study inc. sed.
Gobiodon okinawae Sawada, Arai & Abe, 1972 VI I,10 I,9 15 - - 27
[17]
unpublished data Gobiidae
Gobiosoma hemigymnum (Eigenmann and Eigenmann 1888) VII I,11 I,9 17 I,5 17-19 27
[16]
van Tassell et al. 2015 Gobiidae
Gobiosoma spp. - - - - - - 27-28
[15-17]
Birdsong et al. 1988 Gobiidae
Gobulus spp. - - - - - - 27-28
[16-17]
Birdsong et al. 1988 Gobiidae
Gobulus spp. VII-VIII I,9-13 I,7-13 15-17 I,5 15-18 27-28
[16-17]
Hoese and Reader 2001 Gobiidae
Gobiomorphus alpinus Stokell, 1962 III-VII I,7-9 I,8-10 - - 16-19 29-31 McDowall 1994 Eleotridae
Gobiomorphus spp. III-VIII I,7-10 I,7-10 - - 13-21 27-31 McDowall 1975 Eleotridae
Gobiomorphus spp. - - - - - - 28-31
[16-19]
Birdsong et al. 1988 Eleotridae
Thalasseleotris       16     27
[17]
Hoese and Larson 1987 Thalasseleotrididae
 

gierlChristoph Gierl. Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Richard-Wagner Straße 10, 80333 Munich, Bavaria, Germany; This email address is being protected from spambots. You need JavaScript enabled to view it.

Christoph Gierl is a palaeontologist and a scientific assistant at the Ludwig-Maximilians Universität (LMU) Munich. There he got his Master degree in Geological Sciences. His interests lie in taxonomy, systematics and palaeogeography of fossil gobiiforms. He is currently working on a project on their fossil record and phylogeny.

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reichenbacherBettina Reichenbacher. Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Richard-Wagner Straße 10, 80333 Munich, Bavaria, Germany; This email address is being protected from spambots. You need JavaScript enabled to view it.

Bettina Reichenbacher is professor for palaeontology at LMU Munich. She is interested in the evolution of Miocene teleost groups in the context of the geological history. Current projects comprise the evolutionary history of the European Gobiiformes, the cichlid fossils from Miocene palaeolakes in the Central Kenya Rift and the Iranian killifish genus Aphanius.
Further information on the two latter projects can be found here:
http://www.en.palaeontologie.geowissenschaften.uni-muenchen.de/forschung/forsch_gebiete/kenya/index.html
http://www.killi-data.org/infoweb18.php