Vegrandichthys coitecus, Díaz-Cruz & Alvarado-Ortega & Giles, 2020

Díaz-Cruz, Jesús Alberto, Alvarado-Ortega, Jesús & Giles, Sam, 2020, A long snout enchodontid fish (Aulopiformes: Enchodontidae) from the Early Cretaceous deposits at the El Chango quarry, Chiapas, southeastern Mexico: A multi-approach study, Palaeontologia Electronica (a 30) 23 (2), pp. 1-27 : 8-15

Vegrandichthys coitecus sp. nov.

zoobank.org/ 9CDD4D86-98BE-46BC-B19C-7018293E3350

Holotype. IHNFG 5927 , an almost complete fish transferred to polyester resin, which exposes the left side of the body ( Figures 3-6 ).

Locality and age. Early Cenomanian laminated limestones of the Cintalapa Formation exposed in the El Chango quarry, Ocozocoautla de Espinosa Municipality, Chiapas, southeastern Mexico.

Etymology. The species epithet is in reference to the word ‘coiteco’, which is the local given name to the people from Ocozocoautla de Espinosa Municipality.

Diagnosis. Long-snout fish with a moderately elongated trunk; head length almost one third of the body length; small stout ventroposterior spine on the preopercle; large ventroposterior spine on the cleithrum; articulation between the quadrate and mandible laterally exposed; many lateral thickened ridges on the opercle; tiny pelvic fin in subabdominal position; predorsal scutes series consisting of four large and ovoid scutes that are intensely ornamented with tubercles and bearing a medial longitudinal keel; and lateral line scales triangular, smooth, and bearing a prominent medial keel.

Description

Measurements and general proportions. IHNFG 5927, holotype and only known specimen of Vegrandichthys coitecus gen. et sp. nov. is a gracile, small, and almost complete specimen, in which the entire caudal fin and postanal preural vertebrae are missing ( Figure 3A ). Table 1 summarizes the measurements and body proportions of this specimen. The standard length in this fish is unknown; however, this feature can be estimated as the length of the preserved part in this fish is 50 mm and the postanal region of the trunk ranges between a fifth to a seventh of the standard length in other members of Eurypholinae , Eurypholis , and Saurorhamphus (see Goody, 1969, figs. 47 and 55). Based on these data, the estimated standard length of IHNFG 5927 is between 59 and 61 mm.

The head length (HL) is 19.6 mm and probably represents 32 to 33% of standard length. The orbital and postorbital regions of the skull show the same length and together represent 40% of the skull length; the remaining 60% corresponds to the snout or preorbital region.

The body of IHNFG 5927 is shallow and fusiform. The head height (HH) is relatively shallow, representing a little less than 40% of the head length (HL) and is slightly less than the maximum body height that is present in the predorsal region of the trunk. The dorsal fin is short and placed in the posterior half of the abdominal cavity; the dorsal fin length and the predorsal length represent 25% and 150% of HL, respectively. The posterior end of the anal fin is unknown; however, it is longer than the dorsal fin and is located behind it. The anal fin base is at least 5.5 mm (28% of HL) and rises at 203% of HL. The pectoral fin is in the lateral surface of the trunk, a little closer to the abdominal edge than to the vertebral column. The small pelvic fin is in ventral position and located in the predorsal region of the trunk, at 136% of the HL. Behind the dorsal fin, the trunk progressively tapers and probably behind the anal fin forms a shallow caudal peduncle.

Skull. The skull is triangular, anteriorly tapered, and about three times longer than high ( Figure 4 ). Although the contact of the mesethmoid with the anterior tips of the frontals is covered by the anterior dorsal ends of the premaxilla, the frontals are likely at least three-quarters the length of the skull roof. The left frontal is dorsally exposed showing its flat and triangular shape, anteriorly pointed, slightly wider behind the orbit, and rectangular in the postorbital region. Behind the orbit, each frontal is firmly sutured with four bones; laterally with the sphenotic and pterotic and posteriorly with the supraoccipital and parietal. The supraorbital sensory canal runs along the frontal, near its lateral edge, enclosed above the orbit and exposed in its preorbital region. The frontals are superficially smooth along the preorbital region; in contrast, behind the orbit the frontals and other bones are strongly ornamented with small tubercles. The parietals are short triangular bones at the back of the skull roof, expanded laterally, and medially separated by a small supraoccipital bone.

The sphenotic is a small and triangular bone bordering the dorsoposterior orbital region; the pterotic is an elongated rectangular bone that reaches the back of the skull ( Figure 4 ). The posttemporal fossa is a small depression in the region where the frontal, pterotic, and sphenotic converge. The dilator fossa is a shallow elongated depression laterally extended along the posterior two thirds of the pterotic and roofed by the sphenotic. The parasphenoid is an elongated laminar and straight bar extended along the orbital and the ethmoid region of the skull, with a flat and smooth lateral surface bearing numerous micro-serrations along the ventral edge of its posterior half.

None of the bones of the posterior region of the skull are exposed except for the epiotic, which seems to be short and wide. Much of the lateral otic region of the skull is covered by the hyomandibula. In the preorbital region, the lateral ethmoid is a thick triangular and somewhat curved bone that separates the nasal capsule from the orbit, it sutures with the ventral inner surface of the frontal, and ventrally projects below the parasphenoid. The anterior edge of the nasal capsule is covered by the lateral process of the mesethmoid bone, which is an expanded triangular and flat structure that meets the lateral anterior end of the frontal and is covered by the dorsal edge of the premaxilla ( Figure 4 ).

Circumorbital series. The circumorbital bones are poorly preserved ( Figure 4 ). This is an open series, with no dorsal bones. Remains of flat, rectangular, and flimsy infraorbital bones from the left and right sides of the head are preserved below the nasal capsule and the middle orbit. All these bones show the infraorbital sensory canal running near to their respective orbital edges, as well as few ventral branches of this canal. A large semicircular and flat basal sclerotic bone occupies the orbit.

Suspensorium. Bones of the suspensorium or hyomandibular series are only partially exposed ( Figure 4 ). The hyomandibula is a large T-shaped bone in which the descending process is curved forward and the head is broad with a sinuous articular surface. The central region of this bone is reinforced with apicobasal ridges.

The quadrate is a laminar triangular bone with a small stout ventral head that is inclined forward. The symplectic and the joint between the ventral tip of the hyomandibular and the quadrate are obscured. The ectopterygoid is a laminar and toothless bone that is only partially exposed; its anterior region lies below the lower jaw while its spatula-like posterior part is tilted backward to meet with the quadrate anterior edge. The metapterygoid is laminar and poorly preserved, contacting the concave anterior margin of the hyomandibula and the dorsal edge of the quadrate. Only fragmentary, laminar, and toothless remains of the endopterygoid are preserved.

Although the dermopalatine is entirely covered by the premaxilla, a large, robust dermopalatine tooth is visible. This tooth seems to be placed at the anterior end of the bone, has a stout base, and a conical crown slightly curved backward and projected downward. The dermopalatine appears to bear multiple teeth, but the smaller posterior teeth are difficult to distinguish with precision.

Upper jaw. The upper jaw consists of two bones, the premaxilla and maxilla ( Figure 4 ). There is no indication of a supramaxilla. The premaxilla is a flat triangular bone, pointed posteriorly, and extends for three quarters of the jaw. This bone has a single row of small, conical, sharp teeth, which are of similar size and evenly separated, except for a series of progressively smaller teeth along the posterior quarter of the bone. The anteriormost maxillary tooth is peculiar because it is slightly larger and rather sigmoidal. The dorsal ends of both maxillae are bent inwards to form the roof of the anterior half of the snout. A small midline fenestra, near the tip of the snout, presumably accommodated two teeth from the lower jaws. The outer surface of the premaxilla is intensely ornamented with small tubercles. Fragments of the maxilla reveal that this toothless, smooth, and rod-like bone is extended below the orbit.

Lower jaw. Three bones of the lower jaw are exposed in IHNFG 5927: dentary, anguloarticular, and retroarticular ( Figure 4 ). In lateral view, the lower jaw is elongate, extending below the orbit and the anterior half of the otic region of skull. The first two fifths of its length are shallow, and it becomes progressively deeper more posteriorly: its deepest point is four times the depth of its shallowest point. Both the alveolar and ventral border are somewhat sinuous, the symphysis is very shallow, and the coronoid process is hardly recognizable. At the base of its posterior edge, the jaw has a small posteriorly-directed postarticular process. The mandibular sensory canal runs close to the ventral edge of the lower jaw. It is enclosed by bone, and opens through six pores scattered along the dentary and the anguloarticular bones. The entire labial surface of this jaw is ornamented with numerous tubercles.

The dentary is a triangular bone, occupies a large part of the lower jaw, and has a posterior deep and acute concavity to suture tightly with the anguloarticular bone ( Figure 4 ). The alveolar bor- der of the dentary occupies about two thirds of the jaw and bears two rows of teeth. The labial tooth row includes conical teeth in two sets: groups of one to three small and gracile conical teeth intercalated with larger isolated teeth with thicker bases. The lingual dentary tooth row consists of at least four sharp laterally compressed teeth exposed in the middle of the alveolar border, which resemble the longer teeth on the labial teeth row but they are thinner. Of the labial dentary teeth, the second isolated tooth is so developed that, in life, its tip must have penetrated the premaxilla through its dental fenestra. Since the specimen has single premaxillary dental fenestra, it is possible that the anterior ends of both dentaries were either very close or met in a long symphysial contact.

Although the ventral anterior end of the dentary does not have osseous beards or dentary prongs (cf those of other enchodontids: Enchodus, Goody, 1969 , figs. 36, 39; Unicachichthys, Díaz-Cruz et al., 2016 , figs. 5, 6; Veridagon, Díaz-Cruz et al., 2019b , fig. 3), it does display a series of conspicuous bony lumps. At this point, it is not possible to decide whether these osseous lumps are a preservation artifact, an analogy, or a homology of the dentary prongs of other specimens. In the absence of additional fossils, the authors consider that Vegrandichthys coitecus gen. et sp. nov. lacks dentary prongs.

The anguloarticular occupies the posterior 40% of the lower jaw ( Figure 4 ). This triangular bone bears the postarticular process in which the small and shallow articular facet for the quadrate is exposed in lateral or labio-lingual view. A tiny wedge-shaped retroarticular covers the posteroventral corner of the postarticular process.

Opercular series. This series consists of three laminar bones, opercle, subopercle, and preopercle; the infraopercle is absent ( Figure 4 ). The opercle is semicircular, about twice higher than long, and anteriorly straight and thick. An articular facet for the hyomandibular is borne near its anterior edge about a third of the way down. Seven thickened bars are present on the opercle, laterally exposed as longitudinal straight ridges; the central ridge is the most conspicuous. As the posterior edge of the opercle is very thin, it is not clear whether the bars form true spines or not. The lower third of the opercle is superficially ornamented with tubercles.

The preopercle is a triangular bone, about 2.5 times higher than long, dorsally pointed, ventrally convex, and expanded anteriorly and posteriorly (= “widens anterior and posteriorly” in Fielitz, 2004) ( Figure 4 ). The anterior edge is thickened, slightly convex, and its base is expanded anteriorly; in contrast, the posterior edge of the preopercle is rather laminar, convex, bears small serrations, and its base forms a posterior thick and conspicuous spine. The preopercle is smooth except for small tubercles borne on its ventroposterior limb. The preopercular sensory canal is enclosed by bone and opens externally through two or three pores present in the ventroanterior preopercle limb.

Although the subopercle is poorly preserved and largely covered by the opercle, some remains of this laminar bone are preserved behind the preopercle and below the opercle. Apparently, the subopercle is ornamented with small tubercles ( Figure 4 ).

Branchiostegal rays and gill arches. No element of the branchiostegal rays or the gill arches are exposed.

Vertebral column. Unfortunately, the specimen does not preserve the posterior part of the body; however, a large part of the vertebral column is exposed and consists of at least 30 total vertebrae, including 21 abdominal and at least nine caudal ( Figures 3A , 5 , 6A ). All centra are hourglassshaped bones and slightly constrained in the center. The centra in the middle of the body are about two times longer than high, while those placed in front and back are slightly and progressively shorter, and become about 1.5 times longer than high. Laterally, a couple of thick longitudinal ridges reinforce the centra. Along the vertebral column, the centra have no parapophyses or zygapophyses, and each centrum is fused with its respective dorsal and haemal arches and spines. The haemal and neural spines are uniformly thick, straight and inclined backward. In the abdominal centra, ribs are present as bars with a small articular head and a sharp distal tip.

At least two supraneurals are present below the predorsal scutes and between the occiput and the dorsal fin rays ( Figure 6B ). These spatula-like bones have a differentiated dorsal head that is anteriorly and posteriorly expanded, as well as an anteriorly directed elongated and straight ventral limb. Along the abdominal centra there are thread-like epineurals inclined backward that probably extended along three or four centra from the lateral surfaces of the neural arches. Remains of posteriorly directed thread-like epipleurals are present along the abdominal region.

Pectoral girdle and fin. Pectoral girdle bones are relatively poorly preserved or obscured ( Figures 4 , 5A ). Only fragments of the left posttemporal bone are present behind the skull of the specimen. Most of the supracleithrum is covered by the opercle; only its dorsal end is exposed. The cleithrum is an inverted T-shaped bone in which the dorsal and anterior limbs are not completely observed. The posterior limb of the cleithrum forms a large spiny ventral process that projects posteriorly, and its longitudinal axis is reinforced by a conspicuous ridge. The cleithrum seems to be a smooth bone except for the posterior spine that is ornamented with small tubercles. No postcleitra are preserved.

The left pectoral fin is located above the ventral posterior spine of the cleithrum ( Figure 5A ). This fin consists of six distally branched and segmented rays. Only fragments of the coracoid are preserved. The length of the pectoral fin equals four and a half abdominal vertebrae ( Figure 3 ).

Pelvic girdle and fin. The pelvic fin is set on the anterior half of the abdomen on its ventral border and rises below the abdominal centrum 10. The length of the pelvic fin hardly equals that of two abdominal centra. This fin consists of five distally segmented and branched rays, which are supported on the posterior edge of the pelvic bone. This triangular bone has a laminated triangular lateral wing and a stout and short posterior process ( Figure 5B ).

Dorsal fin. The dorsal fin is contained within the posterior half of the abdominal cavity ( Figure 3 ). It consists of 12 distally branched and segmented rays supported by 11 stick-like proximal pterygiophores ( Figure 5C ). This fin is rounded because the length of those rays in the middle of the fin equals the length of the base while those placed on the front and back are progressively shorter. The base of this fin is extended above the last six abdominal centrae (15-21). The dorsal fin rays are located close to the body because of the lack of distal pterygiophores.

Anal fin. The anal fin originates posteriorly to the dorsal fin ( Figure 3 ). The posterior edge is not preserved, but there are 13 longitudinally grooved and distally segmented rays supported by 13 rod-like and straight proximal pterygiophores ( Figure 5D ). In the posterior two thirds of the anal fin, there are noticeably elongated distal pterygiophores causing the separation of the associated anal rays. Although the anterior anal fin rays are fragmented; it seems that the fin was roughly triangular in shape. The anal fin extends below the vertebrae 25 to 31; however, its first three proximal pterygiophores are projected into the space between the haemal spines of the first caudal centra (22 and 23).

Caudal skeleton and fin. The caudal fin is not preserved.

Squamation. The body is almost entirely naked ( Figures 3A , 6 A-D). However, the predorsal trunk edge bears a row of four predorsal scutes. The lateral line is enclosed by a single row of modified scales exposed along each body flank.

The predorsal scutes are ovoid structures, about two times longer than wide, forming a continuous row where the posterior end of one scute is in contact with the anterior tip of the subsequent scute ( Figures 4 , 6 A-B). These scutes consist of a median longitudinal keel with a pointed posterior margin. Either side of the keel, a semi-ovoid lateral wing expands laterally to cover the predorsal edges of both body flanks. The entire outer surfaces of these scutes are intensely ornamented with numerous tubercles.

The modified flank scales of the lateral line are thin sinuous structures with rounded edges. A prominent keel is present on the midline, and either side of this is a posteriorly projecting subrectangular lobe ( Figures 3 , 6 C-D). In the abdominal region these scales are rectangular, slightly higher than long, around two thirds the length of each vertebral centrum, and are placed slightly above the vertebral column. In contrast, the scales close to the caudal region are progressively smaller, shallower, and located at the level of the centra. The longitudinal axis of these scales encloses a tube that housed the lateral sensory canal. Additionally, above the canal, each scale has a conspicuous, laminar, and triangular keel that projects posteriorly.

Taxonomical Remarks

The family Enchodontidae has been studied by many authors ( Fielitz, 2004; Silva, 2007; Fielitz and González-Rodríguez, 2010; Silva and Gallo, 2011; Cavin et al., 2012; Díaz-Cruz et al. 2016, 2019a), who agree on its monophyly but disagree over the inclusion of Rharbichthys and the composition of its subfamilies. Vegrandichthys coitecus gen. et sp. nov. exhibits some of the characters already included in the diagnosis of this family, such as the lack of interopercle and supraorbital, the presence of the horizontal strengthening bar on the opercle, tubercles ornamenting the opercle and subopercle, and a series of predorsal scutes between the occiput and the dorsal fin ( Figures 3- 6 ). Therefore, the inclusion of Vegrandichthys into the family Enchodontidae is strongly supported.

Additionally, Vegrandichthys coitecus gen. et sp. nov. possesses a peculiar combination of characters that is unique among enchodontid genera. Most enchodontids have preopercles with no posterior spines; however, Vegrandichthys and Unicachichthys share the presence of a posterior spine at the base of the preopercle. Such spine is short in Vegrandichthys ( Figure 5 ) compared to that of Unicachichthys ( Díaz-Cruz et al., 2016, fig.5).

Among enchodontids, as previously known, there are five different body patterns defined based on the different shapes of the snout and trunk: 1) a short snout and rather pisciform trunk as in Enchodus , Unicachichthys , and Veridagon [see Figure 1 ]; 2) a short snout and rather rounded, short and high trunk, as in Parenchodus ; 3) a short snout and very long trunk as in Palaeolycus ; 4) a moderately long snout and perciform trunk as in Eurypholis ; 5) a long snout and very long trunk as in Saurorhamphus . The body pattern displayed by Vegrandichthys gen. nov. resembles that of Eurypholis ; however, the length of the snout is intermediate between those seen in Eurypholis and Saurorhamphus .

Additionally, among enchodontids the articulation between the lower jaw and the quadrate shows two conditions. This articulation is laterally covered by a posterior extension of the anguloarticular bone in Eurypholis and Saurorhamphus , but laterally exposed in other enchodontids. Vegrandichthys gen. nov. shares the second condition with Enchodus , Parenchodus , Unicachichthys , Veridagon , and Palaeolycus .

Finally, among enchodontids, the opercle also shows two conditions. The posterior border of this bone is rounded and continuous in Enchodus , Parenchodus , Unicachichthys , Veridagon , and Palaeolycus . In contrast, in Eurypholis and Saurorhamphus the longitudinal crest in the middle of this bone is extended, forming a posterior spine. Again, in this case Vegrandichthys gen. nov. shows the first of the conditions; however, this new fish is unique because it has additional strengthening longitudinal crests in the preopercle.

Phylogenetic Results

The Standard Maximum Parsimony (SMP) analysis retained one most parsimonious tree of total length 316 steps (CI = 0.456 and RI = 0.693) ( Figure 7 ). The SMP analysis resolves Enchodontidae as a monophyletic family comprising the genera Enchodus , Eurypholis , Palaeolycus , Parenchodus , Saurorhamphus , Unicachichthys , Veridagon , and the monospecific genus herein described, Vegrandichthys .

In this phylogenetic exercise, Vegrandichthys coitecus gen. et sp. nov. is supported as an enchodontid by the presence of four synapomorphies ( Figure 5 ; node a): i) anteroventral prongs present; ii) supraorbital bone absent; iii) pelvic fin at or posterior to the dorsal fin; iv) opercular and subopercular dermal pattern as ridges with tubercles along each ridge. Vegrandichthys is placed in Eurypholinae as the sister taxon of the clade composed by Eurypholis + Saurorhamphus , on the basis of a single character: ventral portion of the cleithrum anterior and posteriorly widened ( Figure 7 ; node d). Overall, in our phylogenetic analysis, the Bremer and bootstrap values across the retained tree are low.

The placement of Vegrandichthys coitecus gen. et sp. nov. as a member of Eurypholinae was also consistent in all the additional phylogenetic analyses carried out. The analysis based on Phylogenetic Morphometrics (PM) of the preopercle landmark configuration retained only one tree with best score = 0.04079. This phylogenetic hypothesis suggests, in addition, a close relationship between Unicachichthys and Eurypholinae ( Figure 8 A-B).

The phylogenetic analysis with Implied Weighted Maximum Parsimony (IWMP) recovered the same topology regardless of parameters (k=10 and k=100; Figure 8C ). However, the best score was different for each analysis (k=100:1.6622; k=10; 12.9163). These results show the same phylogenetic relationships displayed in the analysis of SMP for all the taxa.

The phylogenetic hypothesis obtained with Bayesian Inference (BI) shows a very different topology with respect to those obtained with other methods ( Figure 8D ). Nevertheless, Eurypholinae keeps the same composition, and Vegrandichthys retains its phylogenetic placement in the subfamily.

The analysis combining morphological discrete data with the landmark configuration of the preopercle retained only one tree with tree length=316.04924, of which 0.04924 is the preopercle configuration contribution ( Figure 8E ). The phylogenetic position of the new taxon and the composition of Eurypholinae agree with the topology recovered with SMP, IWMP and BI.

In all the performed analyses the support values of the clades in the subfamily Eurypholinae , as well as their posterior probabilities, are among the highest values across the tree.

On the other hand, the stratigraphic fit analysis showed that the inclusion of Enchodus zimapanensis decreased the level of stratigraphic fit of Enchodontidae : stratigraphic fit is far more consistent in the analyses that excludes E. zimapanensis ( Figure 9). Randomly generated ages in the first analysis improved slightly the stratigraphic fit, but in the second analysis they decreased it.

Figures

FIGURE 1. Enchodontid species from the El Chango quarry, Chiapas, Mexico; A, IHNFG-2987, holotype of Unicachichthys multidentata; B, IHNFG-5816, holotype and single specimen of Veridagon avendanoi. Scale bar equals 1 cm.

FIGURE 3. A) Lateral view of Vegrandichthys coitecus gen. et sp. nov., IHNFG 5927 holotype transferred in plastic resin from Early Cenomanian deposits of the El Chango quarry, Chiapas, Mexico. B) Artistic reconstruction of Vegrandichthys coitecus gen. et sp. nov.

FIGURE 4. Vegrandichthys coitecus gen. et sp. nov. A) A close-up of the lateral view of the head; B) Drawing of the head and pectoral girdle in lateral view. Abbreviations: aa, anguloarticular; cl, cleithrum; den, dentary; df, dilatator fossa; dpl, dermopalatine, dpl.t, dermopaltine teeth; ect, ectopterygoid; en, endopterygoid; epo, epiotic; fr, frontals; hy, hyomandibula; io, infraorbital; iosc, infraorbital sensory canal; la, lacrimal; le, lateral ethmoid; mpt, metapterygoid; msc, mandibular sensory canal; mx, maxilla; op, opercle; pa, parietals; pmf, premaxillar fenestra; pmx, premaxilla; pop, preopercle; ps, parasphenoid; pte, pterotic; ptt, posttemporal; q, quadrate; rar, retroarticular; sc, sclerotic; scl, supracleithrum; soc, supraoccipital; sop, subopercle; sp, sphenotic.

FIGURE 5. Close-up of different anatomical structures in the holotype of Vegrandichthys coitecus gen. et sp. nov. A) Pectoral girdle and fin, B) Pelvic girdle and fin, C) Dorsal fin and D) Anal fin. All anterior structures are laterally exposed. Abbreviations: cl, cleithrum; co, coracoid; dpt.a, anal fin distal pterygiophores; dra, dorsal fin rays; lw, lateral wing; pb, pelvic bone; pfr, pectoral fin rays; pp, posterior process; ppt.a, anal fin proximal pterygiophores; ppt, proximal pterygiophores; pr, pelvic rays; ra.a, anal fin rays; scl, supracleithrum; v, vertebra.

FIGURE 6. Scutes, scales and associated bones of Vegrandichthys coitecus gen. et sp. nov. A) Dorsal scutes series, B) close-up of the dorsal scutes region, C) close-up of the lateral line of scales, and D) drawing of the probable position and overlapping of the lateral line of scales. Abbreviations. llc, lateral lines canal; l.sc, lateral line scales; v, vertebrae. Ordinal numbers denote the number of dorsal scute. Black arrows point out each of the dorsal scutes. Red arrows point out the supraneurals.

FIGURE 7. Phylogenetic relationships of Enchodontidae including Vegrandichthys coitecus gen. et sp. nov. obtained following the protocol described of the Standard of Maximum Parsimony (TL= 316, CI = 0.456, RI= 0.693). The subfamily Eurypholinae in green background and Enchodontinae in red background. Numbers by nodes indicate the supports values of Bremer/Bootstrap. Black squares indicate the presence of synapomorphic characters in Enchodontidae. Node a, Enchodontidae: presence of anteroventral prongs (36:1); absence of supraorbital bone (43:1); pelvic fin at or posterior to the dorsal fin in position (52:1); opercular and subopercular dermal pattern as tubercles (55:2). Node b: Laminar posterior limb in the ventral portion of the preopercle (50:0). Node c: Ectopterygoid teeth between six to eight teeth with the second tooth longest (12:2). Node d, Subfamily Eurypholinae: Ventral portion of cleithrum widens anteriorly and posteriorly (60:2). Node e: Laterally exposed articulation mandible-quadrate (34:1); Opercular horizontal strengthening ridge continues past posterior edge to form a spine (52:2). Node f: Mandibular dermal pattern as ridges with tubercles along each ridge (41:2); Preopercular dermal pattern as ridges with tubercles (54:2). Node q: Sigmoidal lateral view of dermopalatine teeth (16:2). Numbers by nodes show the Bremer/Bootstrap values. The subfamily Enchodontinae is only supported by homoplastic characters, therefore, we omitted them in the node description. Full description and character mapping are in Appendix II.

FIGURE 8. Results of the inclusion of Vegrandichthys coitecus gen. et sp. nov. in the phylogeny of Enchodontidae using multiple phylogenetic approaches. A) The one retained tree of Enchodontidae with the Phylogenetic Morphometrics (PM) method using only landmark data, the Best Score reached = 0.04079. B) Dots in red correspond to the landmark configuration of the preopercle used to run the PMA. C) Implied Weighted Maximum Parsimony (IWMP) tree (the same tree topology with K=10 and K=100) based exclusively on discrete morphological data. D) Maximum a Posteriori (MAP) phylogeny obtained with Bayesian Inference. E) Tree obtained with the combined matrix of morphological discrete data and the landmark configuration of the preopercle, using Standard Maximum Parsimony; Best score = 316.04924. In green background is the subfamily Eurypholinae, except in A that includes Unicachichthys. Background in red is the clade formed by Parenchodus + Enchodus species. In all the phylogenetic analyses Vegrandichthys coitecus gen. et sp. nov. new is recovered as a member of the subfamily Eurypholinae along with Eurypholis and Saurorhamphus. Numbers by nodes indicate Bremmer / bootstrap (when present) values except in D, where numbers indicate the posterior probability. Full phylogenetic hypotheses and their description can be accessed in Appendix II.