Tlaloc Álvarez & Carranza, 1951

Domínguez-Cisneros, Sara E., Domínguez-Domínguez, Omar, Velázquez-Velázquez, Ernesto & Pérez-Rodríguez, Rodolfo, 2023, Redescription and diagnoses of the genera Profundulus and Tlaloc (Cyprinodontiformes: Profundulidae), Mesoamerican endemic fishes, Neotropical Ichthyology (e 220089) 21 (1) : -

Tlaloc Álvarez & Carranza, 1951

Tlaloc Álvarez, Carranza, 1951:40 (type species Fundulus labialis Günther, 1866 , by monotype).

Diagnosis. Tlaloc , one of the two genera of the family Profundulidae , is diagnosed here by the following combination of characters: The mesethmoid is prominent and oval in shape, extending beyond the posterior margins of the vomer, encompassing the posterior medial extension and touching the lateral ethmoids ( Fig. 2B). The anterior portion of the parasphenoid making contact with the mesethmoid and extend beyond the center of the mesethmoid. The autopterotic fossa is reduced ( Fig. 2A). The dorsal margin of the interoperculum, with a long extension, is exceeding the edge of the bone ( Fig. 3A). The ventral margin of the lacrimal is straight ( Figs. 4A–B). Tlaloc is further distinguished from Profundulus by having less than the basal half of the caudal fin densely scaled (except in T. portillorum ) (vs. more than the basal half or more densely scaled) ( Fig. 5A); by the absence of a humeral spot (vs. humeral spot present); by the origin of the dorsal fin positioned at a vertical line posterior to the origin of the anal fin (vs. origin of the dorsal fin positioned at a vertical line slightly anterior to the origin of the anal fin); by long epiotic processes, extending beyond the second vertebra (vs. short epiotic processes, not extending beyond the first vertebra).

Description. Morphometric data appear in Tab. 1. Body uniformly slender; head compressed, moderately large (22.4–36.7%). Mouth subterminal to terminal. In T. hildebrandi and T. portillorum , the lower jaw broad, heavy, and protruding so that the upper jaw is included, whereas in T. labialis and T. candalarius both equal in forward projection, or the lower jaw is included in the upper jaw. Greatest body depth in the vertical just posterior to pectoral fin (20.0–32.6%). The females are elongated, and the males are more robust than the females. Dorsal and anal fins located posterior to the half of body length. Caudal peduncle relatively large (16.2–26.4%). Median hypural plate divided into subequal parts by an open groove.

Percents of standard length

Head length

26.3–30.5 (28.7) 24.1–30.8 (26.8) 26.2–31.6 (28.8) 26.9–35.3 (29.4) 26.8–35.3 (29.1) 26.1–33.9 (28.6) 27.4–33.4 (30.8)

Predorsal length

65.5–72.2 (69.0) 61.9–71.7 (65.5) 64.1–69.8 (67.0) 63.7–69.3 (66.9) 63.9–70.5 (67.1) 64.7–73.5 (68.2)

66.3–77.4

(69.4)

Prepelvic length

47.9–57.3 (52.2) 48.1–55.5 (51.4) 48.2–54.0 (51.7) 49.2–54.4 (51.5) 51.0–57.2 (53.8) 49.0–57.6 (53.3) 50.2–56.4 (53.9)

Anal origin to caudal base

25.2–32.6 (29.1) 29.2–37.1 (33.4) 29.7–36.8 (34.0) 29.0–37.4 (33.3) 30.8–37.8 (34.0) 29.4–37.9 (33.3) 27.1–35.6 (31.2)

Body, greatest depth

23.5–30.8 (26.6) 25.2–31.0 (27.8) 21.2–30.0 (25.7) 26.3–33.8 (30.2) 23.7–31.2 (26.9) 20.4–31.0 (26.1) 24.3–30.8 (27.5)

Body, greatest width

14.4–18.6 (16.5) 11.9–22.2 (17.4) 10.8–18.7 (14.2) 13.2–21.4 (17.8) 10.6–18.6 (15.0) 11.3–20.8 (15.1) 15.4–19.4 (17.5)

Caudal peduncle, length

Caudal peduncle, Least depth

Dorsal fin, basal length

11.1–19.6 (14.8)

11.9–16.6 (14.4)

12.8–17.7 (15.2) 15.5–20.8 (17.2)

11.8–15.9 (13.8)

12.5–19.2 (15.2) 15.5–21.7 (18.5)

12.4–16.2 (14.4)

13.3–18.1 (15.5) 14.3–20.0 (17.9)

14.1–16.9 (15.3)

11.6–18.6 (15.0) 17.3–23.2 (19.7)

11.9–15.9 (13.7)

11.9–17.2 (14.2) 15.5–21.9 (18.0)

11.7–15.4 (13.6)

11.7–18.3 (14.7) 14.2–19.9 (17.0)

13.9–17.4 (15.3)

12.5–16.5 (14.7)

Anal fin, basal length

11.7–18.5 (14.7) 13.2–21.0 (16.1) 13.7–18.3 (15.8) 13.2–19.0 (16.1) 12.7–18.9 (15.3) 13.5–19.4 (16.2) 12.6–18.9 (15.2)

Percents of head length

Head depth

66.4–101.5 (81.0) 56.1–80.6 (69.3) 60.1–90.7 (75.0) 58.3–83.3 (70.5) 59.7–82.9 (73.2) 59.0–80.2 (71.9) 59.9–70.5 (65.8)

Head width

60.1–72.3 (65.0) 57.9–75.5 (68.1) 44.5–70.8 (60.9) 53.8–77.6 (68.5) 52.9–72.2 (65.7) 54.8–97.5 (67.6) 61.0–71.7 (65.6)

Interorbital, least bony width

41.5–48.3 (44.3) 38.7–55.9 (50.3) 38.1–48.5 (44.1) 38.9–58.7 (50.2) 38.2–52.7 (45.1) 38.9–50.2 (46.0) 45.9–52.7 (48.7)

Orbit length

21.2–26.3 (23.8) 21.4–28.9 (25.0) 20.4–31.3 (25.2) 21.5–28.9 (25.4) 23.1–30.0 (26.3) 20.5–28.5 (23.6) 22.0–32.6 (28.0)

Snout length

24.0–32.2 (28.8) 15.4–34.9 (25.3) 27.2–38.5 (32.5) 22.2–34.2 (29.2) 27.3–37.8 (32.6) 26.6–38.2 (33.5) 28.7–37.9 (33.1)

21.8–36.1 11.1–23.9 24.3–34.4 11.2–30.0 24.3–35.9 21.1–36.6 23.5–32.0 Upper jaw length (26.9) (16.5) (28.7) (18.4) (29.7) (33.5) (26.4)

The branching pattern of the cephalic latero-sensory canals in Tlaloc is similar to the general pattern of the Cyprinodontiformes . The supraorbital series follows the Type II designation of Gosline (1949), with canals between pores 1–2a, 2b–4a, 4b–7; preopercular pores 6–7 (mode = 7); preorbital pores 3–5 (mode = 4); mandibular pores 4–5 (mode = 5); in addition, there are 2 to 4 rostral pores usually developed.

Meristic characters are as follows ( Tab. 2): anal: 9–18; dorsal: 7–14; pelvic: 5–7; pectoral: 13–20; caudal: 16–23; vertebrae totals: 33–38; gill rakers on anterior arm of the first arch: 13–19; branchiostegal rays: 6; scales lateral series: 29–39; scales predorsal: 19–26; scales around body: 25–36; scales around peduncle: 16–28.

Coloration. The coloration varies strongly among individuals and ontogenetically. The skin of the head and body may show golden reflections, especially in the opercular region and mid flank. The form and coloration of the nuptial adult male and female are shown in Fig. 6. Unpaired fins (dorsal and anal) are orange in males, with irregular black markings on the dorsal fin, evident in Tlaloc candalarius .

Anal rays 13–18 (16) 11–16 (14) 11–16 (15) 9–14 (13) 11–16 (14) 12–15 (14) Pectoral rays 16–20 (18) 14–19 (15) 15–18 (16) 13–17 (15) 14–19 (17) 16–18 (17) Caudal rays 20–23 (20) 16–23 (20) 17–23 (22) 17–23 (20) 18–24 (21) 18–24 (21) Pelvic rays 5–7 (6) 5–7 (6) 5–7 (6) 5–7 (6) 5–7 (6) 6–7 (6) Lateral scales 33–39 (37) 30–39 (34) 33–37 (36) 29–34 (33) 29–34 (33) 30–33 (33) Scales predorsal 21–26 19–26 (23) 20–24 (22) 21–26 (23) 18–24 (20) 20–23 (22)

Scales around body

28–36 25–35 (31) 27–33 (30) 25–31 (28) 24–30 (26) 26–29 (28)

Scales around peduncle 18–22 (21) 16–21 (18) 16–21 (18) 16–22 (19) 17–25 (20) 18–23 (19) Vertebrae 37–38 (37) 33–36 (35) 36–37 (36) 33–34 (33) 32–34 32–33 (33)

Gill rakers 13–18 (16) 14–19 (17) 14–19 (16) 13–17 (15) 15–21 (17) 15–19 (17)

Sexual dimorphism and contact organs. There is little sexual dimorphism in species of the genus Tlaloc . Males are slightly larger than females; the largest specimen recorded was a male from Tlaloc hildebrandi (111.49 mm SL), whereas the maximum size recorded in a female was in Tlaloc labialis (101.93 mm SL). The shape of the anal fin, however, shows a marked sexual difference: the anterior anal rays of the male are not greatly longer than the posterior ones, giving the distal margin of the fin an evenly rounded edge. However, in the female, since the medial rays, from about the sixth to the tenth, are much longer than either the anterior or the posterior rays, the distal margin of the fin is lobate when expanded. Males have contact organs or spinules, articulated with the lateral surfaces of the anal fin rays with some of them conspicuously long; this is the most notable, though not striking difference between males and females of all Tlaloc species ( Fig. 7).

Geographical distribution. Restricted to the Atlantic slope of Middle America ( Fig. 8). From the border between Oaxaca and Chiapas, Mexico, to the center of Honduras, with the exception of Tlaloc portillorum , this is located on both slopes of Honduras, Atlantic and Pacific.

Etymology. Tlaloc in reference to Tlaloc , a deity of water in Aztec mythology

(Álvarez, Carranza, 1951).

Nine species are recognized in the genus Profundulus (Morcillo et al., 2016; Del Moral-Flores et al., 2020; Domínguez-Cisneros et al., 2021): P. punctatus (Günther, 1866) , P. guatemalensis (Günther, 1866) , P. oaxacae (Meek, 1902) , P. balsanus , P. kreiseri Matamoros, Schaefer, Hernández & Chakrabarty, 2012 , P. mixtlanensis Ornelas-García, Martinez-Ramírez & Doadrio, 2015 , P. parentiae Matamoros, Dominguez-Cisneros, Velázquez-Velázquez & McMahan, 2018 , P. chimalapensis Del Moral-Flores, López-Segovia & Hernández- Arellano, 2020, and P. adani Dominguez-Cisneros, Velázquez-Velázquez, McMahan & Matamoros, 2021 .