Profundulus Hubbs, 1924

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 : 13-15

Profundulus Hubbs, 1924

Profundulus Hubbs, 1924:12

(type species Fundulus punctatus Günther, 1866 , by original designation).

Diagnosis. Profundulus is diagnosed here based on the following characters: The mesethmoid is small, crescent-shaped, and does not extend beyond the margin of the vomer ( Figs. 2C–D ); the vomer is greatly broadened anteriorly, lacks lateral processes and is in contact with the lateral ethmoids; the anterior portion of the parasphenoid is just in contact with the mesethmoid and does not extend beyond the center of the mesethmoid; the autopterotic fossa is large ( Fig. 2D ); the dorsal margin of the interoperculum, with a short extension, does not exceed the edge of the bone ( Fig. 3B ); the ventral margin of the lacrimal slightly concave ( Figs. 4C–D ). Profundulus is further distinguished from Tlaloc in having more than the basal half of the caudal fin densely scaled (except in P. kreiseri ) (vs. less than the basal half of caudal fin densely scaled) ( Fig. 5B ); by a humeral spot (except in P. adani ) (vs. humeral spot absent) ( Fig. 5B ); by the origin of the dorsal fin positioned at a vertical line slightly anterior to the origin of the anal fin (vs. origin of the dorsal fin positioned at a vertical line posterior to the origin of the anal fin); by short epiotic processes, not extending beyond the first vertebra (except in P. parentiae ) (vs. long epiotic processes, extending beyond the second vertebra).

Description. Morphometric data appear in Tab. 2 . Body rather robust, elongate; head compressed, large (24.1–35.3%); the interorbital broad (38.2–58.7%) and typically concave or nearly flat. Ascending premaxillary process short and broad and bluntly rounded at the tip. Mouth subterminal, lower jaw broad, heavy and protruding so that upper jaw is included. Dorsal fin rounded in both males and females with its basal length short (11.1–19.2%). Anal fins of males rounded, slightly elongated in females. Caudal peduncle relatively short (11.1–23.2%). Median hypural plate divided into subequal parts by an open groove.

Lateral-line system of sensory canals and pores on the head of Profundulus : The supraorbital series follows the Type II designation of Gosline (1949), with canals between pores 1–2a, 2b–4a, 4b–7; preopercular pores 6–8 (mode = 7); preorbital pores 3–5 (mode = 4); mandibular pores 4–5 (mode = 5); generally, there is a lack of rostral pores, exceptionally there may be 2 to 4 in some species.

Meristic traits are as follows ( Tab. 2 ): anal: 11–17; dorsal: 10–15; pelvic: 5–7; pectoral: 13–19; caudal: 17–24; vertebrae totals: 31–35; gill rakers on anterior arm of the first arch: 14–22; branchiostegal rays, 6; scales lateral series: 29–35; scales predorsal: 18–29; scales around body: 23–35; scales around peduncle: 16–25.

Coloration. The form and coloration of the nuptial adult male are shown in Fig. 5B . Most of the body dark, often with irregular brown-dark spots on the scales, on the sides of the body on to the caudal fin. A golden yellow blotch covers the operculum and reaches the base of the pectoral fin.

Sexual dimorphism and contact organs. The sexual dimorphism is not very evident in species of the genus Profundulus . However, the males are slightly larger than females; the largest specimen recorded was a male from P. guatemalensis (83.9 mm SL), while the maximum size recorded in a female was in P. adani (77.9 mm SL). In males and females of all species of Profundulus , the dorsal and the anal fins have a similar morphology. Like Tlaloc ( Fig. 7 ) the males of Profundulus 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 Profundulus species.

Geographical distribution. On the Pacific slope, from the río Malinaltepec, río Papagayo basin, of Guerrero, southeastern Mexico, southward to the río Lempa in El Salvador and Honduras; on the Atlantic slope, from the upper reaches of the río Papaloapan of Oaxaca, Mexico, to the ríos Chamelecón and Ulúa in northwestern Honduras ( Fig. 8 ).

Etymology. Profundulus in reference to its presumed primitive relationship to the genus Fundulus (Parenti, 1981) .

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 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.