Paleocharacodon guzmanae, Caballero-Viñas & Alvarado-Ortega & Severiano, 2023

Caballero-Viñas, Carmen, Alvarado-Ortega, Jesús & Severiano, Kleyton Magno Cantalice, 2023, A Pliocene goodeid fish of the Paleolake Amajac, Sanctórum, Hidalgo, Mexico, Palaeontologia Electronica (a 30) 26 (2), pp. 1-39 : 21-27

Paleocharacodon guzmanae , a New Goodeidae

Smith (1980) divided Goodeidae into two large groups. His Characodon-group shares two features, the anguloarticular bone (=articular-angular) has a dorsal process projected almost vertically, forming a nearly right angle with the anterior process, and the articular head of the quadrate is comparatively short and hardly protrudes from the anterior edge of the palatopterygoid complex. On the contrary, in his Goodea-group, the anguloarticular has a dorsal process strongly projected backward beyond the articular process and forming an

Species Status and distribition

1. Allodontichthys hubbsi Miller and Uyeno, 1980 . Endangered. Upper Coahuyana River Basin. Jalisco .

2. Allodonthichthys polylepis Rauchenberger, Vulnerable. Upper Ameca River Basin. Jalisco

1988.

3. Allodontichthys tamazulae Turner, 1946 . Vulnerable. Coahuayana River Basin. Jalisco .

4. Allodontichthys zonistius Hubbs, 1932 . Vulnerable. Armeria River Basin. Colima and Jalisco .

5. Alloophorus robustus Bean, 1892 . Vulnerable. Cotija, Cuitzeo, Pátzcuaro, Zacapu, Zirahuén, Santiago, and Balsas basins. Michoacán and Jalisco.

6. Allotoca catarinae De Buen, 1942 . Critically endangered. Upper Cupatizio River Basin. Michoacán .

7. Allotoca diazi Meek, 1902 . Critically endangered. Lake Pátzcuaro Basin. Michoacán .

8. Allotoca dugesii Bean, 1887 . Endangered. Middle and lower Rio Lerma Basin and upper Rio Santiago Basin. Michoacán, Guanajuato , and Jalisco.

9. Allotoca goslinei Smith and Miller, 1987 . Extinct in wild. Arroyo Potrero Grande in Ameca River basin. Jalisco.

10. Allotoca maculata Smith and Miller, 1980 . Critically endangered. Santa Magdalena Lake Basin. Jalisco . 11. Allotoca meeki Álvarez, 1959 . Critically endangered. Lake Zirahuén Basin. Michoacán .

12. Allotoca zacapuensis Meyer, Radda, and Critically endangered. Lake Zacapu Basin. Michoacán .

Domínguez, 2001.

13. Ameca splendens Miller and Fitzsimons, 1971 . Critically endangered. Upper Ameca River basin , Teuchitlán springs. Jalisco.

14. Ataenobius toweri Meek, 1904 . Endangered. Pánuco Basin, Verde River and La Media Luna Lagoon. San Luis Potosi.

15. Chapalichthys encaustus Jordan and Synder, Vulnerable. Chapala Lake and adjacent portions of Lower Lerma 1899. basins. Jalisco and Michoacán.

16. Chapalichthys pardalis Álvarez, 1963 . Critically endangered. Springs near Tocumbo, San Juanico,

Michoacán.

17. Chapalichthys paraticus Álvarez, 1963 . Endangered. San Juanico reservoir. Cotija, Michoacán.

18. Characodon audax Smith and Miller, 1986 . Endangered. Ojo de agua de las Mujeres. Durango.

19. Characodon garmani Jordan and Evermann, Extinct. Parras Valley, Nazas-Aguanaval River basin, Mayrán

1898. Lagoon. Coahuila.

20. Characodon lateralis Günter, 1866 . Critically endangered. Mezquital River Basin. Durango .

21. Crenichthys baileyi (Gilbert, 1893) . Endangered. White River system, springs of Moapa River. Southeastern Nevada.

22. Crenichthys nevadae Hubbs, 1932 . Vulnerated. Railroad Valley. Nye County, Nevada .

23. † Empetrichthys erdisi Uyeno and Miller, 1962 . Fossil (Pliocene). Santa Clara River Valley, in the Piru Mountains, Ventura County, California.

24. Empetrichthys latos Miller, 1948 . Critically Endangered (only introduced). Pahrump Valley, Nye County, Nevada.

25. Empetrichthys merriami Gilbert, 1893 . Extinct. Ash Meadows, Amargosa Desert, Nye County, Nevada.

26. Girardinichthys multiradiatus Meek, 1904 . Endangered. Basins of Balsas, upper Lerma, and Tuxpan rivers; Zempoala lake . Estado de México, Michoacán , and Morelos.

27. Girardinichthys viviparus, Bustamante, 1837 . Endangered. Valley of Mexico Basin, Río Tula. Estado de México, Mexico City , and Hidalgo.

28. Goodea atripinnis Jordan, 1880 . Least Concern. Widely distributed in basins of Lerma, Santiago, Balsas, Armeria, Ameca and River, as well as Tierra Quemada, Zirahuén, Zacapu, Chapala, and Pátzcuaro lakes. Hidalgo, Jalisco, San Luís Potosí, and Michoacán. Recently, it was discovered in the Río Metztitlán, Pánuco Basin. Hidalgo (Miranda et al., 2010).

Species Status and distribition

29. Hubbsina turneri De Buen, 1940 . Critically endangered. Cuitzeo basin, Yuriria reservoir and Zacapu Lake in Lerma River Basin. Guanajuato and Michoacán .

30. Ilyodon cortesae Paulo-Maya and Trujillo- Threatened. San Juan Tacámbaro River , Michoacán .

Jiménez, 2000.

31. Ilyodon furcidens Jordan and Gilbert, 1882 . Least Concern. Marabasco, Armeria, and Ameca River basins. Colima and Jalisco.

32. Ilyodon lennoni Meyer and Förster,1983 . Vulnerable. Chacambaro stream, Lerma River Basin. Guerrero.

33. Ilyodon whitei Meek, 1904 . Vulnerable. Balsas River basin. Jalisco, Michoacán, Morelos, Puebla , and Guerrero.

34. Neoophorus regalis Álvarez, 1959 . Critically endangered. Balsas River basin in the Los Reyes. Michoacán.

35. † Paleocharacodon guzmanae . Here. Fossil (Pliocene). Sanctórum site. Hidalgo.

36. Skiffia bilineata Bean, 1887 . Endangered. Cuitzeo Lake and Lerma River basins. Michoacán and Guanajuato .

37. Skiffia francesae Kingston, 1978 . Extinct in wild. Teuchtitlán, Ameca River basin. Jalisco

38. Skiffia lermae Meek, 1902 . Endangered. Pátzcuaro, Zirahuén, Cuitzeo, Zacapu lake basins; Lerma River . Michoacán and Guanajuato .

39. Skiffia multipunctata Pellegrin, 1901 . Endangered. Lower Lerma River Basin, Lake Chapala , and the upper part of the Santiago River basin. Jalisco and Michoacán .

40. † Tapatia occidentalis Álvarez and Arreola- Fossil (Pliocene). Amatitán. Jalisco.

Longoria, 1972.

41. Xenoophorus captivus Hubbs, 1924 . Endangered. Upper Pánuco River basin, springs in the Venados, Moctezuma, and Agua de Enmedio; Santa María del Río and Tierra Quemada rivers; Jesús María reservoir. San Luis Potosi.

42. Xenotaenia resolanae Turner, 1946 . Vulnerable. Marabasco and Purificación River basins. Pacific slope of Jalisco.

43. Xenotoca doadrioi Domínguez-Domínguez, Critically Endangered. Hacienda San Sebastián pond, El Moloya Bernal-Zuñiga, and Piller, 2016. spring, Estancia de Ayoles reservoir, Oconahua Dam. Etzatlán region, in Jalisco.

44. Xenotoca eiseni Rutter, 1896 . Endangered. Santiago River basin and Compostela River,

Magdalena Lake basin, and upper parts of Ameca and Coahuayana River basins . Nayarit and Jalisco.

45. Xenotoca lyonsi Domínguez-Domínguez, Critically Endangered. Middle and upper part of the Coahuayana Bernal-Zuñiga, and Piller, 2016. River Basin; Tuxpan and Tamazula rivers. Jalisco.

46. Xenotoca melanosoma Fitzsimons, 1972 . Endangered. Magdalena Lake and the Ameca, Armería, Santiago, and Coahuayana River basins. Jalisco.

47. Xenotoca variata Bean, 1887 . Least concern. Pánuco River Basin, middle Lerma River basin, and upper Santiago River basin; and Cuitzeo and Zacapu Lake basins. Aguascalientes, Jalisco, Guanajuato, Querétaro , and Michoacán.

48. Zoogoneticus purhepechus Domínguez- Vulnerable. Lower Lerma River, including Duero, Grande, and Domínguez, Pérez-Rodríguez, and Doadrio, 2008. Santiago rivers; Upper Ameca River ; Chapala Lake; and Magdalena, Sayula, San Marcos, Zacoalco, and Atotonilco lagoons. Michoacán and Jalisco.

49. Zoogoneticus quitzeoensis Bean, 1898 . Endangered. Middle and lower Lerma River Basin, upper part of basins of Santiago, Armeria, Ameca rivers, Chapala Lake.

Michoacán and Jalisco.

50. Zoogoneticus tequila Webb and Miller, 1998 . Endangered. Teuchitlán springs, upper Ameca River Basin , Jalisco.

obtuse angle with the anterior process; additionally, here, the articular head of the quadrate is comparatively longer and projects in advance of the anterior edge of the palatopterygoid complex (Smith, 1980, figures 16, 17). Although Smith (1980) considered Ameca , Hubbsina , and Tapatia occidentalis as goodeids of uncertain position, the subsequent reviews of these taxa reveal that their anguloarticulars have a vertical dorsal process (Guzmán 2010, figure 4b; Webb, 1998), suggesting that these may form part of his Characodon-group.

In this context, it is impossible to include Paleocharacodon guzmanae gen. and sp. nov. in any of the goodeid groups proposed by Smith (1980). This Mexican fossil fish shows the condition of the anguloarticular described in the Characodon-group, as well as the quadrate having an articular head comparatively long and protruding forward as in the Goodea-group ( Figures 6 , 8D ). Additionally, Tapatia occidentalis and P. guzmanae differ in the shape of the anguloarticular and jaw teeth. In T. occidentalis , the length of the anguloarticular anterior process is at least 2.5 times the height of its dorsal process. The teeth in the frontal rows of jaws show a bicuspid or bifid shape, end in two square lobes loosely separated, and are distally truncated or straight (Guzmán, 2010, figures 4b, 5 c”). On the contrary, in P. guzmanae , the proportions of the anguloarticular are less contrasting. That length is just about 1.3 times such height, and the teeth of principal rows have bicuspid and sharp ends ( Figures 6 , 10 , 11 ).

Also, Paleocharacodon guzmanae differs from Hubbsina and Ameca in the size and position of the dorsal fin. In P. guzmanae , the dorsal fin is short, has 12-15 rays, and is entirely opposed to the anal fin ( Table 1, Figure 13 ). Although the dorsal fin in Ameca is short and has only 13-14 rays, in Hubssina, this fin is peculiarly long and consists of 29-37 rays; in both cases, the dorsal fin is placed more to the front and opposes the anal fin only in part (De Buen, 1940; Miller and Fitzsimons, 1971; Domínguez-Domínguez et al., 2005, p. 540, 552). As a result, P. guzmanae is considered a new genus and species.

Unfortunately, after the efforts of Parenti (1981) and Webb (1998), who included some osteological features to define the naturalness of the family Goodeidae and recognize its interrelations under the cladistic scope ( Figure 15 ), this type of data ceased to be considered in phylogenetic assays. Therefore, under these conditions, it is necessary to analyze, recognize and assess the possible osteological differences between these fishes, a task already in progress that will take a few more years to be helpful. In this paper, we explore the affinities of Paleocharacodon guzmanae gen. and sp. nov. within Goodeidae , ana-

lyzing the distribution of its osteological features along the branches of those hypotheses proposed by these authors. Table 4 summarizes the comparative analysis of P. guzmanae and other extant and extinct goodeid taxa.

In the restructuring of Goodeidae suggested by Parenti (1981, p. 515-516) to include the subfamilies Goodeinae and Empetrichtyinae, she noted that these fishes share four diagnostic features (1-4 below and in Figure 15 ). Later, Webb

(1998) discovered other distinctive features of the family (5-7 in this paragraph and Figure 15 ); however, among these features, only two are synapomorphies (3 and 5). In this context,

Paleocharacodon guzmanae gen. and sp. nov. is an unquestionable member of Goodeidae because it shows six of these diagnostic features (Figure

15):

1) In the anal fin, the most anterior 2 to 7 medial pterygiophores (= middle radials) are absent as autogenous bones because these are fused with the respective proximal pterygiophores (= proximal radials of Parenti, 1981, figure 83, node A) ( Figure 13 ).

2) The dorsal process of the maxilla is strongly reduced (Parenti, 1981, figure 83, node A) ( Figures 6 , 8D ).

3) The distal arm of the premaxilla is straight (Smith, 1980; Parenti, 1981, figures 40C, 83 node A) ( Figures 6 A-B; 8D); according to Webb (1998, ch. 649), this is a synapomorphy.

4) The anguloarticular (=articular in Parenti, 1981, p. 406, figures 33B, C, D, and node A in figure 83) is significantly reduced, and its medial extension does not carry the mandibular sensory canal.

5) In lateral view, the lacrimal bone is somewhat rectangular and at least twice as higher as long; according to Webb (1998, figures III.22B, ch. 658) is a synapomorphy ( Figure 5 ).

6) The ascending process of the premaxilla is small or reduced (Parenti, 1981, figure 39C; Webb, 1998, ch. 650) ( Figure 6 ). In goodeids, in dorsal view, the pterotic (=autopterotic) bones show a narrow autopterotic fossa

7) in Figure 15 , in which the otic sensory canal runs (Uyeno and Miller, 1962; Parenti, 1981; Webb, 1998, figures III.12B, ch. 641); unfortunately, any of the specimens of P. guzmanae herein studied show that fossa.

Figures

FIGURE 5. Details of IGM 13125 (part), paratype of Paleocharacodon guzmanae gen. and sp. nov., from the lacustrine deposits of the Paleolake Amajac, in Sanctórum, Hidalgo, central Mexico. A) Head observed under white light. B) Unborn fishes preserved in the abdominal cavity, observed under UV light. Abbreviatures: fr, frontal; la, lacrimal; let, lateral ethmoid; psp, parasphenoid (note its anterior end, bifid and with no lateral expansion); black arrows show articulated vertebrae of unborn fishes; red arrows show the pectoral fin of an unborn fish.

FIGURE 6. μCT imagens of IGM 13127, paratype of Paleocharacodon guzmanae gen. and sp. nov., from the lacustrine sediments of the Paleolake Amajac, in Sanctórum, Atotonilco El Grande Municipality, Hidalgo, central Mexico. A) Left side of the head and anterior part of the trunk. B) Quadrate and bones of both jaws exposed on the right side. C) Close-up of bones involved in the articulation quadrate-lower jaw showing the bilobed head of the quadrate and the articular facet of the anguloarticular in which there is a central participation of the retroarticular (here disarticulate and displaced from its normal position) and two enveloping projections of the anguloarticular. D) Right view of the hyoid arch. The scale only applies to A, B and D. Abbreviations: 1, 2a, 2b, 3, pores of the supraorbital sensory canal; aa, anguloarticular; bh, basihyal; br, brachiostegal ray; bst, bicuspid sharp tooth; cha, ceratohyal anterior; chp, ceratohyal posterior; cl, cleitrum; co, coronomeckelian; id; cor, coracoid; d, dentary; dsp, dermosphenotic; entp, entopterygoid; epi, epioccipital; fr, frontal; hy, hyomandibula; ih, interhyal; iop, infraopercle; let, lateral ethmoid; mx, maxilla; na, nasal; op, opercle; pa, parietal; pcli, postcleitrum inferior; pmx, premaxilla; pop, preopercle; psp, parasphenoid; ptt, posttemporal; q, quadrate; r, rib; rar, retroarticular; scl, supracleitrum; soc, supraoccipital; sp, sphenotic; sop, subopercle; sy, symplectic; uh, urohyal; ust, unicuspid sharp tooth; utt, unicuspid truncated tooth; vhh, ventral hypohyal; dubious elements; within parenthesis: i, internal view (if it is not indicated, the structures show the right view); l, left; r, right; va, ventroanterior view; vp, ventroposterior view.

FIGURE 8. Osteological details of Paleocharacodon guzmanae gen. and sp. nov., from the Paleolake Amajac deposits, Sanctórum, Mexico. A) Close-up of the right side of the head of IGM 13118 showing the medial surface of the left otoliths. B) Left anguloarticular bone of IGM 13121 showing the articular facet for the quadrate formed by a surrounding C-shaped process (note this in the shadow below), as well as the central participation of the retroarticular bone that here is empty (see the red line) because this bone is not preserved. C) Right dentary bone and associated teeth of the part of IGM 13121. D) Suspensorium of IGM 13123. E) Dorsal surface of the lateral process of right sphenotic, preserved in IGM 13130. F) Abdominal region of IGM 13130. G) Close-up of pharyngeal teeth preserved in the counterpart of IGM 13121. Abbreviations: aa, anguloarticular; aadp, anguloarticular dorsal process; aapp, anguloarticular anterior process;ast, asteriscus otolith; bst, bicuspid sharp tooth; cor, coracoid; d, dentary; d, dentary; entp, entopterygoid; epn, epineural; faq, articular facet for the quadrate; hy, hyomandibula; lap, lapillus otolith; mx, maxilla; pal, palatine (note the anterolateral projection in the head); pmx, premaxilla; pmx, premaxilla; pop, preopercle; q, quadrate; r, rib; sag, sagittal otolith; sc, scale; sop, subopercle; sp, sphenotic; sy, symplectic; ust, unicuspid sharp tooth. The red arrow in B shows the space in the articular facet for the square (which should be occupied by the retroarticular bone) surrounded by the pair of curved processes of the anguloarticular that also forms part of such facet (see also the shadow of the process)

FIGURE 10. Bones of the jaws preserved in IGM 13121, a female specimen of Paleocharacodon guzmanae gen. and sp. nov., from the Paleolake Amajac deposits, Sanctórum, Mexico. A) closeup of the anterior part of the head under white light. B) Line drawing based on A. Abbreviations: aa, anguloarticular; bst, sharp bicuspid tooth; co, coronomeckelian; d, dentary; mx, maxilla; pl, palatine; pmx, premaxilla; sop, subopercle; ust, unicuspid sharp tooth. In parenthesis i, internal view; l, left; r, right.

FIGURE 11. Jaw teeth of Paleocharacodon guzmanae gen. and sp. nov., IGM 13130, a male specimen from the Pliocene Paleolake Amajac deposits in Sanctórum, Hidalgo, Mexico, observed under UV light. A) Short acute bifid tooth from a lateral position of the principal row of premaxilla; B) long acute bifid tooth from the anterior position of the principal row of the dentary; C) villiform tooth from posterior rows on the dentary anterior region.

FIGURE 13. Impaired fins of Paleocharacodon guzmanae gen. and sp. nov., from the Pliocene Amajac Paleolake deposits in Sanctórum, Hidalgo, Mexico, observed under UV light. A) Dorsal fin of IGM 13129 (sex undefined; the distal ends branched and segmented of the dorsal rays are covered). B) Anal fin of IGM 13121 (male with anal rays 2 and 13 only preserved as impressions; since the bone of tips of these rays is not-preserved, the arrows show the anterior short rays forming the andropodium and the posterior rays forming a rounded fin). Abbreviations: afr, anal fin ray; amp, anal medial pterygiophore; app, anal pterygiophore; dfr, dorsal fin ray; dmp, dorsal medial pterygiophore; dpp, dorsal proximal pterygiophore.

FIGURE 15. Phylogenetic hypotheses of the family Goodeidae. The numbers indicate the distribution of osteological features. Underlined numbers are synapomorphies; not underlined numbers are homoplasies; bold characters are those shared by Paleocharacodon guzmanae gen. and sp. nov.; italic characters are those which P. guzmanae shows an alternative condition or state; characters in normal font are those unknown in this new species. (Continued next page.)