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), pp. 1-22 : 5-13

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.

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 .

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 .

Figures

FIGURE 2 | Ventral view of the neurocranium, in specimens cleared and stained. A. Tlaloc portillorum (MZ-UNICACH 7222, 70.5 mm SL); B. Vomer region of T. candalarius (MZ-UNICACH 3899, 61.7 mm SL); C. Vomer region of Profundulus kreiseri (MZ-UNICACH 7214, 59.6 mm SL); and D. Neurocranium of P. mixtlanensis (MZ-UNICACH 6716, 55.6 mm SL). Abbreviations: V, vomer (Y-shaped); E, lateral ethmoid; M, mesethmoid; P, parasphenoid; AF, autopterotic fossa.

FIGURE 3 | Lateral view of left jaws, suspensorium and opercular series in specimens cleared and stained. A. Tlaloc portillorum (MZ-UNICACH 7222, 70.5 mm SL); B. Profundulus mixtlanensis (MZ-UNICACH 6716, 55.6 mm SL). Arrow points to dorsal margin of the interoperculum, with a long or short extension. Abbreviations: de, dentary; pm, premaxilla; ra, retroarticular; mx, maxilla; pl, palatine; qu, quadrate; ar, articular; ms, mesopterygoid; io, interopercle; sy, sympletic; hy, hyomandibula; po, preopercle; op, opercle; so, subopercle.

FIGURE 4 | Ventral view of left lacrimal. A. Tlaloc portillorum (MZ-UNICACH 7222, 70.5 mm SL); B. T. hildebrandi (MZ-UNICACH 2266, 75.1 mm SL); C. Profundulus mixtlanensis (MZ-UNICACH 6716, 55.6 mm SL); and D. P. punctatus (MZ-UNICACH 6632, 67.3 mm SL). Arrow point to ventral margin of the lacrimal.

FIGURE 5 | Male general morphology and caudal fin squamation, life colour patterns in: A. Tlaloc labialis; and B. Profundulus punctatus. Solid arrow points to the squamation of the caudal fin, dashed arrow points to the humeral spot.

FIGURE 6 | Tlaloc candalarius. A. Male (MZ-UNICACH 7567, 71.4 mm SL); B. Female (MZ-UNICACH 7567, 78.8 mm SL); note the orange coloration of the dorsal and anal fins in the male.

FIGURE 7 | Bony spinules in fin rays of male Tlaloc labialis, indicated by arrow (MZ-UNICACH 6740, 75.7 mm SL), articulated with the lateral surfaces of the anal fin rays.

FIGURE 8 | Geographical distribution of species of the genera Tlaloc and Profundulus in southern Mexico and Central America.

Tables

TABLE 1 | Morphometric data of Tlaloc and Profundulus species. Asterisk mark the number of specimens analyzed, in parenthesis the average values.

	Tlaloc portillorum 58*	T. hildebrandi 63*	T. labialis 58*	T. candalarius 100*	Profundulus punctatus 196*	P. guatemalensis 26*
Standard length (mm)	37.6–71.4 (50.4)	37.9–111.5 (58.2)	33.4–101.9 (53.1)	38.8–99.2 (51.6)	36.2–82.2 (50.3)	38.4–83.9 (51.8)
Percents of standard length
Head length	25.7–32.0 (28.9)	26.8–32.2 (28.3)	22.4–31.6 (26.9)	26.3–36.7 (29.4)	26.1–32.6 (29.1)	27.0–31.1 (28.9)
Predorsal length	66.1–73.6 (69.6)	64.2–68.5 (66.3)	65.0–70.4 (67.4)	63.6–73.8 (69.7)	62.2–74.7(68.0)	65.5–71.5 (68.4)
Prepelvic length	47.7–55.2 (51.1)	45.8–51.8 (48.9)	46.8–54.7 (50.6)	48.9–61.1 (53.7)	47.0–57.6 (52.2)	49.8–53.6 (51.5)
Anal origin to caudal base	29.0–36.7 (33.4)	36.3–41.9 (39.1)	32.3–41.8 (36.1)	27.3–39.7 (33.3)	19.3–37.4 (33.2)	31.9–36.7 (34.5)
Body, greatest depth	20.0–27.8 (25.2)	22.1–29.7 (24.6)	20.2–29.9 (24.4)	20.7–32.6 (27.7)	21.0–33.6 (28.5)	25.7–31.5 (29.0)
Body, greatest width	11.8–17.0 (14.5)	12.5–17.6 (14.8)	10.6–18.1 (14.3)	11.5–19.5 (15.6)	14.3–22.8 (18.3)	10.8–18.2 (14.7)
Caudal peduncle, length	16.3–23.5 (19.8)	20.3–26.4 (23.3)	17.8–23.6 (21.5)	16.2–24.0 (19.5)	13.7–21.8 (18.3)	15.5–22.1 (18.8)
Caudal peduncle, Least depth	12.6–15.9 (14.3)	12.0–15.1 (13.4)	12.6–15.1 (13.5)	11.4–16.6 (13.5)	13.9–18.3 (15.7)	14.2–16.1 (15.2)
Dorsal fin, basal length	11.1–16.5 (14.1)	11.7–17.6 (14.1)	11.6–16.4 (14.0)	11.1–17.7 (13.9)	11.1–18.3 (15.0)	12.5–16.6 (14.7)
Anal fin, basal length	12.1–17.4 (14.3)	14.0–19.1 (16.0)	12.7–19.5 (15.5)	12.3–17.5 (14.5)	11.6–20.1 (15.7)	14.3–18.6 (16.0)
Percents of head length
Head depth	55.6–98.0 (67.3)	53.3–85.4 (62.5)	57.5–76.2 (67.0)	56.6–100.1 (68.5)	56.5–94.9 (72.7)	64.8–101.7 (86.0)
Head width	49.3–72.9 (59.6)	49.2–71.0 (64.6)	54.8–70.6 (62.1)	49.2–70.0 (60.7)	58.8–80.6 (68.7)	55.8–75.8 (64.3)
Interorbital, least bony width	37.3–48.7 (42.1)	40.0–48.7 (45.2)	41.1–51.7 (46.2)	34.9–48.3 (42.9)	40.0–53.2 (47.2)	43.3–54.1 (47.3)
Orbit length	21.1–28.6 (24.5)	18.0–28.9 (24.8)	24.9–32.7 (28.6)	19.5–30.6 (26.5)	19.0–29.9 (25.4)	21.6–29.2 (24.0)
Snout length	28.8–35.6 (32.7)	29.8–39.7 (34.9)	29.3–39.7 (33.7)	27.5–38.3 (32.8)	25.6–37.4 (32.3)	28.6–36.9 (33.3)
Upper jaw length	23.9–32.9 (28.3)	26.3–35.3 (31.0)	22.1–31.4 (27.6)	21.5–32.3 (27.7)	16.9–31.7 (25.3)	20.7–33.2(29.6.3)

TABLE 2 | Meristic data of Tlaloc and Profundulus species. Asterisk mark the number of specimens analyzed, in parenthesis the modal values.

Character	T. labialis 58*	T. candalarius 102*	T. hildebrandi 63*	T. portillorum 58*	P. punctatus 202*	P. guatemalensis 26*
Dorsal rays	10–14	9–14 (11)	10–14 (11)	7–14 (11)	10–14 (12)	11–13 (12)
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)