Herichthys molango

Maza-Benignos, Mauricio De La & Lozano-Vilano, Ma. De Lourdes, 2013, Description of three new species of the genus Herichthys (Perciformes: Cichlidae) from eastern Mexico, with redescription of H. labridens, H. steindachneri, and H. pantostictus, Zootaxa 3734 (2), pp. 101-129 : 114-117

Herichthys molango n sp.

Figures 10 , 11 , and 15; Tables 4 and 5

Holotype. UANL 10214 (1: 108.9 mm SL, adult male), Laguna Azteca, Hidalgo, México, Lat. 20.80388333, Long. −98.74801667, 1274 masl, M. De la Maza-Benignos, June 30, 2006.

Paratypes. Twenty-two specimens, 83–108.9 mm SL. Hidalgo: UANL 17510 (22: 83–108.9 mm SL), same data as holotype.

Diagnosis. Distinguished from other species in having a slender (slightly broader than long), well-spaced, and indented lower pharyngeal plate; 2 rows of 8–9 medium-sized, lightly pigmented molars flank the midline; 11–13 nonenlarged conic teeth along the posterior margin. Distinguished from all other species in the genus by a combination of the following characters: predorsal contour deep and nonacute, which is not concave before the eye; head short (mean 35%, SD 3%), rostral tip to the pectoral fin origin distance (mean 33%, SD 1%); caudal peduncle short (mean 15%, SD 1%) and deep (mean 16%, SD 1%), long anal fin (origin to hypural base distance; mean 40%, SD 1%); wide preorbit (mean 30%, SD 3%); eye small (mean 21%, SD 2%). Peritoneum is uniformly very dark.

Description. Description is based on sexually mature specimens> 83 mm SL. Morphometric and meristic data are summarized in Tables 4 and 5. Body elongate, depth, 39%–43% (mean 41%, SD 1%) in SL; head short, 33%– 45% (mean 35%, SD 3%) and wide at preorbit, 21%–34% (mean 30%, SD 3%); snout long, 31%–44% (mean 40%, SD 3%); cheeks deep, 24%–35% (mean 32%, SD 3%); eyes small, 16%–23% (mean 21%, SD 2%) [all in HL]; caudal peduncle short, 14%–16% (mean 15%, SD 1%) and deep, 15%–18% (mean 16%, SD 1%) and distance from anal fin origin to hypural base long, 38%–42% (mean 40%, SD 1%) [all in SL]. Predorsal contour deep and nonacute, not concave before eye. Jaws end equally (isognathous). Forehead inconspicouous, nuchal hump absent. Mouth terminal; dorsal and ventral contours straight to moderately convex, and having a moderate slope that changes abruptly posteriorly: dorsal profile abruptly forms a 30° angle with horizontal between base of soft dorsal fin and intersection with caudal peduncle; ventral profile abruptly forms a 45° angle with the horizontal between posterior base of soft anal fin and the intersection with caudal peduncle.

Dorsal fin XVI–XVIII (mode XVII, freq 60%), 10–11 (mode 11, freq 80%); fins set forward with respect to vertical with posterior border of opercle (intersects between 1st and 3rd rays); depressed fins short and rarely extending beyond anterior 3rd of caudal fin. Anal fins V–VII (mode VI, freq 70%), 8–10 (mode 8, freq 40%). Pectoral fins asymmetric and rounded. Caudal fin truncate to subtruncate. Scales in longitudinal series 29–34 (mode 32, freq 40%). Anterior teeth regularly set, well-spaced, conic, unicuspid, rounded, strongly recurved, and acutely pointed, with erect implantation; a pair of well-developed recurved fangs, reddish in color in the upper jaw; a less-developed pair in lower jaw; 14 teeth in outer series of premaxillae, six to eight frontal teeth regularly set, acutely pointed, caniniform and with moderately stout necks; lateral and posterior teeth small, non-caniniform and irregularly set. Two tooth rows in lower jaw and 2 rows in upper jaw; teeth of posterior rows diminutive, irregularly set and hardly visible. Lower pharyngeal plate slender (slightly broader than long) with well-spaced indentation. Two rows of 8-9 medium sized, lightly pigmented molars flanking midline. Non-enlarged conic teeth along posterior margin numbering 11-13. Robust-walled stomach moderately saccular (19.09% of SL), rugged with longitudinal folds and adhered at its anterio-dorsal section to well-elongated elastic smooth caecum (31.5% of SL). Gut-coiling pattern forms double medial loop; secondary loop projecting away from observer and passing under the gut. Peritoneum is uniformly very-dark.

Coloration in preservative. Dorsum and head areas light brown. Flanks tan, belly whitish. Tiny dark speckles at regular intervals along the head and onto snout and gill-covers. Scale-pockets dark, resulting in a reticulate appearance. Markings vary some individuals with dark blotches irregularly spaced on the flanks, some with 8-9 conspicuous markings on flanks below the lateral line with a conspicuous spot in the ventral area of caudal fin. Some with 6 discrete vertical bars corresponding to each blotch; some with no markings. All fins opaque and same color as body.

Live colors. Color light goldenrod to olive in dorsal areas and very light on the flanks and belly. Snout and head densely covered with speckles that extend posteriorly to nuchal area and onto gill cleft. Scales over flanks fringed by diamond-shaped darker outlines (scale-pockets), thicker over posterio-ventral half, giving the flanks a reticulate appearance. All specimens with red marking at axil, behind pectoral fin. Dorsal and caudal fins are same color as the body with four lines of red dots extending onto soft areas and conspicuous on inter-radial membranes. Tip of caudal fin reddish.

Breeding pigmentation. Breeding pigmentation consists of a darkening of the four posterior vertical bands on posterior half of specimens, as well as sections (including the dorsal area) of the 6th and 5th bars, anterioventral three fourths of distance from snout (including upper lip), through the ventral edge of the orbit onto opercles and chest to the XI dorsal spine. Large posterioventral pale areas, especially along the midflank, separate the dark area in half.

Geographical distribution. This species occurs in Laguna Azteca in the headwaters of the Rio Panuco of the Rio Moctezuma Basin, 6 km north of Molango , Hidalgo (20° 48′ N, 98° 45′ O, 1280 masl). This location is a monomictic anoxic warm lake that has a thick hipolimnion and acidic pH, making it a eutrophic system (Díaz- Pardo et al. 2002). The species also possibly occurs in the Rio Santa María, Rio Venados, and Rio Amasa in the states of Queretaro and Hidalgo.

Habitat and associates. Laguna Azteca has a depth of 16 m, transparency of 1–3 m, surface temperatures of 16–27°C, and surface pH of 7–8. This species is not sympatric with other native cichlids. Its natural history was extensively studied by Díaz-Pardo et al. (2002). Tilapia and centrachids ( Micropterus salmoides and Lepomis spp.) have been introduced and are having a devastating impact on the population of H. molango . Stomach contents studied to date include mainly filamentous algae.

Vernacular names. Mojarra Azteca, Aztec cichlid.

Conservation status. Currently considered as C. labridens , threatened by NOM-059-ECOL-2010 and endangered by the IUCN Red List of Threatened Species 2009. Laguna Azteca has been severely impacted by the introduction of largemouth bass ( Micropterus salmoides ) and sunfish ( Lepomis spp.), which greatly threatens the viability of the entire H. molango population.

Etymology. The name refers to the municipality in the State of Hidalgo where Laguna Azteca is located. Molango is derived from the Nahuatl language.

Remarks. Díaz-Pardo et al. (2002) considered H. molango to be a geographic variant of H. labridens and extensively studied its trophic behavior and natural history.

Figures

FIGURE 10. Herichthys molango sp. nov. collected from Laguna Azteca in Molango, Hidalgo, Mexico (~ 100 mm TL).

FIGURE 11. UANL 10214 Herichthys molango sp. nov. Holotype (108.9 mm SL). Mauricio De la Maza-Benignos, Figures 12 – 13.