A New Fossil Genus of Gobiiformes from the Miocene Characterized by a Mosaic Set of Characters
Gobiiformes are one of the most versatile groups among teleosts and show countless adaptations. Their fossil record encompasses numerous otolith-based species, but only a few species that are based on skeletons, and fossil skeletons with otoliths preserved in situ are exceptionally rare. Here, articulated skeletons, some with otoliths in situ, from the lower and middle Miocene of Southern Germany (Illerkirchberg, Öhningen) are re-investigated to clarify whether “Cottus brevis Ag.” and “Cottus brevis Ag.?” correspond to the same species. Our data show that the latter actually represents a previously unrecognized new species, for which we introduce the species epithet gaudanti. In both species, the palatine is T-shaped and the entopterygoid is absent, as is characteristic for the Gobiidae, but the number of branchiostegals is six, which is typical for the sleeper gobies (Eleotrididae and Butidae). This character combination is so far unique and justifies the introduction of Eleogobius, new genus, including E. brevis (Ag.) (as type species) and the new species E. gaudanti. A further outcome is that all otoliths previously described as Gobius multipinnatus (H. v. Meyer) rather belong to E. gaudanti, new species, and that the otoliths of G. multipinnatus remain unknown until a skeleton with otoliths in situ is found. Our results indicate that fossil Gobiiformes may have been much more diverse than the currently known record suggests, and that many fossil species of “Gobius” might not belong to this genus, or indeed even to the Gobiidae.
Drawing of an otolith showing the parameters measured.
(A, B) Eleogobius gaudanti. (A) NMW 1857 XXVII 7. Skeleton with both sagittae preserved in situ. Arrow indicates epineurals. A1: Close-up of left sagitta. A2: Close-up of skull showing T-shaped palatine (PAL) and maxilla (MX). (B) MCZ 5211-A. Part of skeleton showing branchiostegals 1 to 6 and one (1′ or 2′) ray from the other side. (C, D) Eleogobius brevis. (C) NMB On. 19. Skeleton with right sagitta preserved in situ (photo: M. Schellenberger). Arrow indicates epineurals. C1: Close-up of skull showing T-shaped palatine, basihyal (BH), ceratohyal (CHY), ectopterygoid (ECT), premaxilla (PMX), quadrate (Q), symplectic (SYM), urohyal (UH). (D) NMB On. 86. Part of skeleton showing branchiostegals 1 to 6. Scale bars: 1 mm.
Caudal fin skeletons of the two species of Eleogobius. (A) Eleogobius brevis. NMB On. 14. (B) Eleogobius gaudanti. HLMD V3314a (skeleton without skull). Epural (EPU), preural hemal spine (HPU), hypural (HY), preural neural spine (NPU), parhypural (PHY), preural centrum (PU). Scale bar: 1 mm.
(A–P) Otoliths of Eleogobius gaudanti. (A) Druisheim/67.43–67.50/a. (B) Druisheim/67.30–67.45/5d. (C) Druisheim/67.30–6745/5a. (D) Druisheim/67.30–67.45/5c (mirrored). (E) Druisheim/67.30–67.45/3c. (F) Druisheim/67.43–67.50/c. (G) Druisheim/67.43–67.50/2a. (H) in situ from specimen HLMD V 3314b (mirrored). (I) Druisheim/67.26–67.31/2a (SEM image). (J) Druisheim/67.37–67.43/b (SEM image). (K) Druisheim/67.37–67.43 (mirrored, SEM image). (L) Holzheim/41.00–41.11/a (SEM image). (M) Druisheim/67.26–67.31/2b (mirrored, SEM image). (N) Holzheim/40.55–40.60 (mirrored, SEM image). (O) Druisheim/67.43–67.50/b (mirrored, SEM image). (P) Druisheim/67.30–67.45 (SEM image). (Q–Y) Otoliths of Eleogobius brevis. (Q) StMartin_Z1_a (SEM image). (R) StMartin_Z2_a (SEM image). (S) StMartin_Z2_d (mirrored, SEM image). (T) StMartin_Z1_d (mirrored, SEM image). (U) StMartin_Z1_e (mirrored, SEM image). (V) StMartin_Z2_f (mirrored, SEM image). (W) StMartin_Z2_c. (X) StMartin_Z2_b. (Y) In situ from specimen BSPG 2007 III 4; also depicted in Reichenbacher et al. (2007). Scale bar: 1 mm.
Generalized schematic reconstruction of Eleogobius gaudanti, new species. Note that this image should not serve as basis for pterygiophore formula calculation or other quantitative estimations (all countable characters of the fossil specimens are provided in Table 1). Scale bar: 1 mm.
Otoliths from Kienberg. (A) Kienberg_Gp_1. (B) Kienberg_Gp_7. (C) Kienberg_Gp_11 (mirrored). (D) Kienberg_Gp_14 (mirrored). (E) Kienberg_Gp_13 (mirrored). (F) Kienberg_Gp_5. (G) Kienberg_Gp_9 (mirrored). Scale bar: 1 mm.
Contributor Notes
Associate Editor: G. Arratia.