Sciades maldonadonis, Carrillo-Briceño & Mora-Rojas & Hendricks & Vanegas & Aguilera, 2023

Carrillo-Briceño, Jorge D., Mora-Rojas, Laura, Hendricks, Kimberly, Vanegas, Andrés & Aguilera, Orangel, 2023, New clues on the palaeodiversity of the middle Miocene freshwater ichthyofauna from the Tatacoa Desert, Colombia, Geodiversitas 45 (10), pp. 327-351 : 335

† Sciades maldonadonis n. sp.

( Fig. 3 A1-A3)

urn:lsid:zoobank.org:act:A20896FF-45B6-4E90-9A8C-22E9A791748E

DIAGNOSIS. — The combination of extremely depressed lapillus otolith, regularly clam-shaped outline, sharp antero-medial projection, strongly arched dorsal margin anteriorly and oblique-straight posteriorly distinguish † Sciades maldonadonis n. sp. from extant Sciades species, extinct brackish and freshwater species (e.g., † Cantarius Aguilera et al., 2013b ), and extant South American freshwater species ( Chinchaysuyoa Marceniuk et al., 2019a , and Paragenidens Marceniuk et al., 2019a ).

TYPE MATERIAL. — Holotype VPPLT-832 . A complete lapillus otolith ( Fig. 3 A1-A3), preserved length 20.94 mm, width 16.84 mm, thickness 7.08 mm .

TYPE LOCALITY. — La Victoria Fm. Morrongo 1 (see Fig. 1 B; Appendix 1).

DERIVATION OF NAME. — The species is named in honor of Dr Javier Alejandro Maldonado-Ocampo (1977-†2019), renowned Colombian ichthyologist who passed away on 2 March 2019 during an expedition to the Río Vaupés in Colombia. Javier dedicated more than twenty years to the study and conservation of the freshwater fish fauna of Colombia, including the Andes, Orinoco and Amazon basins.

DESCRIPTION

The lapillus otolith is clam-shaped with a semi-circular outline, very depressed dorso-ventrally, and with a sharp antero-medial projection ( Fig. 3 A1, A2). The dorsal margin is strongly arched anteriorly and oblique-straight posteriorly. The ventral margin is strongly arched. The posterior margin forms an obtuse angle. The lateral profile is slightly biconvex. The pseudocauda and the mesial inward curvature are not well preserved. The umbo is located in the center of the dorsal surface. The lapillus length to width ratio: 1.2. Lapillus length to thickness ratio: 3.0.

REMARKS

VPPLT-832 is characterized by a typical Ariidae otolith morphology. The recognition of † Sciades maldonadonis n. sp. as a member of Sciades is based on its otolith morphology, which is characterized by the combination of extremely depressed dorsoventral shape and by the dorsal margin being strongly arched anteriorly, and oblique-straight posteriorly. This allows it to be differentiated from the other Sciades species (for comparative proposes see Aguilera et al. 2020: figs. 4.49-4.60; 6.9-6.12).

Marceniuk et al. (2017) reviewed the genus Sciades and showed a strong morphological relationship between nominal genera Sciades and Ariopsis Gill, 1861 . More than seven extant Sciades species are currently recognized ( Froese & Pauly 2022). The age of diversification of modern species of Sciades is older than 9 Ma (including Sciades dowii Gill, 1863 , from the Pacific), and the age of the Atlantic Sciades species is c. 6.7 Ma (4-8Ma) (Betancur-R.2009). † Sciades maldonadonis n. sp. came from a freshwater palaeoenvironment in the middle Miocene rocks of the Honda Group, associated with a wide diversity of freshwater fishes, crocodylians, snakes, lizards, turtles, and mammals (e.g., Kay et al. 1997; Carrillo et al. 2015; Cadena et al. 2019, 2020; Defler 2019). The ancestral form of freshwater catfish Ariidae otolith-based species from the western Amazon included † Cantarius nolfi Aguilera, Moraes-Santos, Costa, Ohe, Jaramillo & Nogueira, 2013b , and † Cantarius ohei Schwarzhans, Aguilera, Scheyer & Carrillo-Briceño, 2022 , recorded from the Miocene Pebas wetland system at the Pebas Formation ( Carrillo-Briceño et al. 2021b; Schwarzhans et al. 2022). In North, Central, and South America, six extant ariid species are primarily freshwater, including Chinchaysuyoa labiata Boulenger, 1898 , Chinchaysuyoa ortegai Marceniuk, Marchena, Oliveira & Betancur-R, 2019a, Paragenidens grandoculis Steindachner, 1877 , Paragenidens nelsoni Evermann & Goldsborough, 1902 , Paragenidens izabalensis Hubbs & Miller, 1960 , and Paragenidens usumacintae Betancur-R & Willink, 2007 ( Marceniuk & Menezes 2007; Marceniuk et al. 2019a, b). On the other hand, fossil skull-based species of † Sciades latissimum Aguilera & Marceniuk, 2018 , and † Sciades peregrinus Aguilera & Marceniuk, 2018 without preserved internal otolith, were described from the late Miocene Urumaco Fm, Venezuela, characterized by palaeoenvironments associated to a large palaeo-hydrographic system of the Orinoco/ Amazonas discharging into the proto-Caribbean Sea ( Aguilera et al. 2020).

Other ariid remains from the Honda Group include two isolated dorsal-spine fragments ornamented by rugose tuberculations, from the Duke 24 (see Lundberg 1997) and Mini Desierto localities (VPPLT-1108; Figs 1 B, 3 B1-B3). Sedimentary characteristics and the associated fauna from the Honda Group support that VPPLT-832 and the indeterminate ariid spines were from a freshwater palaeoenvironment.

Figures

FIG. 3. — Siluriforms from the Honda Group: A1-A3, complete lapillus otolith (Holotype) of †Sciades maldonadonis n. sp. (VPPLT-832) from the Honda Group. B1-B3, dorsal spine fragment of Ariidae indet.(VPPLT-1108);C1-C3, incomplete neurocranium of Oxydoras sp.(ULA-1316);D-M, Phractocephalus sp.;D, parietosupraoccipital frontal fragment (VPPLT-1272); E, F, parieto-supraoccipital bone fragments; E, VPPLT-1128; F, VPPLT-223; G, pterotic fragment (VPPLT-442); H, sphenotic fragment,VPPLT-421;I, indeterminate fragments,VPPLT-742;J, right pectoral girdle (IGM-s/n°);K-M, pectoral spines fragments;K, M, VPPLT-043; L, ULA-44; N-P, Hoplosternum sp.; N, O, parieto-supraoccipital; N, VPPLT-1453; O, ULA-829; P, left pectoral-fin spine, VPPLT-1250; Q-T, Doradidae indet.; Q, R, parieto-supraoccipital; Q, VPPLT-921; R, ULA-2997; S, T, fragmented pectoral-fin spines; S, VPPLT-43; T, VPPLT-1442; U1, U2, cf. Acanthicus sp., pectoral-fin spine, VPPLT-469; V1, V2, cf. Hypostomus sp., left pectoral-fin spine, VPPLT-504; W, X, Loricariidae indet.; W, skull fragment, VPPLT-1375;X, portion of a caudal fin, ULA-2413. Views: B1, U1, V2, anterior; C1, D-I, N-R, V1, dorsal; A1, dorsal face; C3, left lateral; A3, X, lateral; B2, U2, posterior; B3, J, right lateral; C2, ventral; A2, ventral face; K-M, S-T, W, indet. Abbreviations: acf, anterior cranial fontanel; ad, anterior dentations; adp-cl, anterior dorsal process of cleithrum; cl, cleithrum; fr, frontal; lf, left frontal; lle, left lateral ethmoid; mes, mesethmoid;pas, parasphenoid;pd, posterior dentations;pdp-cl, posterior dorsal process of cleithrum; pp-cl, posterior process of cleithrum; rf, right frontal; rle, right lateral ethmoid; sop, parieto-supraoccipital; vtp, vomeral tooth plate. Scale bars: A, N, V, 6 mm; B, E, F, L, O, Q-S, W, X, 5 mm; C, D, H, I, K, 10 mm; G, 7 mm; J, 20 mm; M, 8 mm; P, 3 mm; T, 4 mm; U, 9 mm.

FIG. 1. — Geographical position (A) of the Honda Group’s stratigraphic section (B) at La Venta site placed in the Upper Magdalena River Valley, Colombia. For details on the localities’ geographic coordinates and stratigraphic position, please see Appendix 2.