Creagrutus peruanus (Steindachner 1876)

Creagrutus peruanus (Steindachner, 1875)

Piabina peruana Steindachner, 1875:596 [type locality: Peru (Ayacucho) Monterico (=Montericco); on page 46 of separate].

Creagrutus nasutus Günther, 1876:400 [type locality: Peru (Ayacucho) Monterico (=Montericco)].—Steindachner, 1878:384

Creagrutus peruanus.—Steindachner, 1878:384 [transfer to Creagrutus; Creagrutus nasutus Günther, 1876, placed as a synonym].—Eigenmann, 1910: 435 [literature compilation]; 1927:420, pl. 35: fig. 4 [Peru: (Ayacucho) Monterico (=Montericco), Santa Ana, Río Comberciato; description based on Günther, 1876].—Eigenmann and Allen, 1942:226 [Peru: (Cuzco) Ríp Urubamba, Santa Ana, Río Comberciato; Río Chanchomayo at La Merced].—Fowler, 1945a:148 [literature compilation]; 1948:84 [literature compilation]; 1975:27 [literature compilation].—Ortega and Vari, 1986:8 [Amazonian Peru, common name].—Ortega, 1992:43 [above 1000 m elevation in Peru].—Not Barriga, 1991:18 [eastern Ecuador].

Creagrutus peruana.—Eigenmann and Eigenmann, 1891:56 [listing; as senior synonym of C. nasutus Günther].

DIAGNOSIS.—The possession of premaxillary dentition with three components generalized for the species of Creagrutus and Piabina, but with a distinct gap between the first and second teeth of primary tooth row and a forward position of the triangular cluster of three posteromedial teeth distinguishes C. peruanus from all members of the clade formed by Creagrutus and Piabina with the exception of Creagrutus maracaiboensis, C. melanzonus, C. muelleri, C. nigrostigmatus, C. ouranonastes, C. runa, and Piabina argentea. Creagrutus peruanus can be distinguished from these seven species by its possession of 9 to 11 branched anal-fin rays, 38 to 40 vertebrae, 10 to 12 predorsal median scales, a narrow third infraorbital falling distinctly short ventrally and posteriorly of the preopercle, the length of the anal fin (18.4%–20.0% of SL), the depth of the caudal peduncle (11.5%–14.0% of SL), and the distance from the dorsal-fin origin to the hypural joint (55.7%–59.0% of SL).

DESCRIPTION.—Morphometric and meristic data for Creagrutus peruanus in Table 45. Overall form of head and body relatively robust, more so in larger examined individuals. Greatest body depth typically at dorsal-fin origin, shifted some what anterior of that point in larger individuals with distended abdomens; relative greatest body depth somewhat greater in larger specimens. Dorsal profile of head distinctly convex anteriorly from margin of upper lip to vertical through posterior nostril, straight from that line to rear of supraoccipital spine. Predorsal profile of body slightly convex and continuing profile of posterior portion of head in small and medium-sized specimens, somewhat more convex in larger individuals, with associated change in alignment at rear of supraoccipital spine between profile of head and that of body. Profile of portion of body posterior to dorsal fin relatively straight at all body sizes. Ventral profile of head slightly convex, but not demonstrating distinct change in angle at anteroventral corner of dentary typical of most Creagrutus species. Prepelvic region of body convex, more so in larger individuals.

Head obtusely pointed in lateral view and more so in dorsal view. Upper jaw longer than, and overhanging, lower jaw. Anterior portion of snout and lateral surface of upper jaw fleshy and covered with numerous papillae; field of papillae continuing from snout and lip onto folds and plicae extending between outer and medial premaxillary teeth. Lower lip fleshy anteriorly, with scattered papillae on anterior and ventral surfaces.

Infraorbital series poorly developed. Ventral margin of third infraorbital falling distinctly short of horizontal limb of preopercle in specimens of all sizes. Distal margin of third infraorbital approximately concentric with orbital rim. Posterior margin of third to fifth infraorbitals falling distinctly short of vertical limb of preopercle even in largest individuals examined.

Premaxillary dentition in three series: primary row curved, with 5 teeth and distinct gap between first and second teeth of series, first tooth separated from anterior tooth of contralateral series by distinct gap, but separation less pronounced than in most congeners; triangular cluster of three teeth, larger than those of primary series, with posterolateral tooth of cluster distinctly largest, anterior tooth of cluster partially in pronounced gap between first and second tooth of primary series, two posterior teeth not in as close contact as in most congeners, posteromedial tooth of triangular cluster very closely applied to matching tooth of contralateral cluster; and single tooth of form similar to that of primary series lying lateral to area of contact of third and fourth teeth of primary row. Maxilla with 3 or 4 tricuspidate teeth. Dentary with 5 or 6 teeth, anterior 5 teeth tricuspidate, these sometimes followed by 1 unicuspidate tooth. Anterior 3 dentary teeth larger than remaining teeth in series, with first and second teeth subequal and twice height of third tooth. Fourth through sixth teeth compressed and gradually decreasing in size posteriorly.

Dorsal-fin rays ii,8–9. Dorsal-fin origin at vertical through pelvic-fin insertion. Profile of distal margin of dorsal fin slightly concave. Anal-fin rays ii,9–11. Profile of distal margin of anal fin slightly concave. Hooks typically present on anal-fin rays in mature males of many Creagrutus species not present in examined specimens. Pectoral-fin rays i, 11–13. Tip of pectoral fin extending posteriorly nearly to pelvic-fin insertion in smaller individuals, falling somewhat short of that point in larger specimens. Pelvic-fin rays i,6,i in smaller individuals, more typically i,7 in larger specimens. Tip of pelvic fin reaching posteriorly to anal-fin insertion. Hooks typically present on pelvic-fin rays in mature males of many Creagrutus species not present in examined specimens.

Gill rakers 6–7+ 8–10.

COLORATION IN ALCOHOL.—Overall ground coloration of relatively recently collected specimens light tan. Dorsal surface of head with scattered, dark chromatophores, region dorsal to brain relatively darker in small individuals. Chromatophore field extending onto snout, with dark chromatophores more concentrated anterior to nares, forming discrete, dark, crescent- shaped patch. Discrete band of chromatophores extending posteriorly from crescent-shaped patch anterior to nares along ventral and posterior margins of orbit. Scattered, dark chromatophores overlying fourth and fifth infraorbitals and dorsal portion of opercle. This region with denser and more intense pigmentation in larger specimens. Dorsal and dorsolateral surfaces of body with scattered chromatophores, chromatophore field denser over center of scales, particularly on dorsal portion of body. Humeral mark vertically elongate and with irregular margins. Pigmentation most intense over center of spot and fading in dorsal and ventral portions of mark. Deep-lying band of midlateral pigmentation extending along body, band beginning 3 to 6 scales posterior of humeral mark and extending posteriorly to caudal peduncle. Deep-lying midlateral band overlain by diffuse surface band formed by field of scattered chromatophores extending from slightly posterior of humeral mark onto caudal peduncle. Band of surface chromatophores somewhat denser and wider proximate to base of caudal-fin rays. Dorsal-fin pigmentation ranging from all rays evenly delimited by dark chromatophores to only anterior rays and central portions of other rays distinctly outlined by dark chromatophores, thus forming indistinct stripe across fin. Anal-fin rays outlined with dark chromatophores; chromatophores sometimes more concentrated along middle portions of rays and forming indistinct band across center of fin. Pectoral and pelvic fins with scattered, dark chromatophores on rays and membranes.

ECOLOGY.—Exact ecological information on the collecting localities of examined specimens is unavailable. All localities are in regions of distinct gradient ranging from more than 500 m to approximately 900 m altitude.

Stomach contents of specimens of Creagrutus peruanus prepared for clearing and staining in this study consisted of approximately equal amounts of chopped larger seeds, whole smaller seeds, and parts of adult and larval insects. At one locality in the Río Chanchamayo, Department of Junin, Peru, C. peruanus was collected along with C. changae.

DISTRIBUTION.—Creagrutus peruanus occurs in portions of the Río Apurimac and Río Urubamba basins in eastern Peru (Figure 74, diamonds).

COMMON NAME.—Peru: “Majorita” (Ortega and Vari, 1986:8).

MATERIAL EXAMINED.—141 specimens (39, 37.2–87.0).

PERU. Ayacucho: Monterico (=? Monterrico, approximately 12°28′S, 73°54′W), NMW 19852, 1 (87.0, lectotype of Piabina peruana); NMW 19853–54 and NMW 19867–71, 7 (45.9–87.0, paralectotypes of Piabina peruana); BMNH 1875.10.12:26, 1 (78.9, lectotype of Creagrutus nasutus); BMNH 1875.10.14:27–33, 6 (61.5–78.2, paralectotypes of Creagrutus nasutus). Cusco: Río Comberciato (Río Compursiato), small tributary of middle Río Urubamba, 30 km above Pongo de Mainique (latter locality at approximately 11°56′S, 72°52′W), at 1800 ft (=555 m) elevation, MCZ 30994, 15; CAS 69314 (formerly IU 13759), 9 (3, 55.8–65.8); FMNH 58066, 4. Middle Río Urubamaba, Santa Ana (12°52′S, 72°43′W), at approximately 3000–3400 ft (=914–1040 m) elevation, CAS 69313 (formerly IU 16050), 2; MCZ 30993, 1. Junin: Provincia Chanchamayo, Río Chanchamayo, Mijandari, highway from La Merced to Villa Rica (11°04′S, 75°20′W), MUSM 1074, 15; USNM 340979, 8 (2, 46.0–50.1; 2 specimens cleared and counterstained for cartilage and bone). Provincia Chanchamayo, Río Colorado, La Merced (11°03′S, 75°19′W), MUSM 5914, 6; USNM 340980, 4 (37.2–46.8); MUSM 8873, 8; USNM 340982, 2. Provincia Chanchamayo, Río Blanco, La Merced, MUSM 5918, 1. Provincia Chanchamayo, La Merced, Río Minjandara (approximately 11°03′S, 75°18′W), MUSM 2974, 12; USNM 340981, 7 (4, 39.8–44.2; 2 specimens cleared and counterstained for cartilage and bone). Provincia Chanchamayo, Río Chanchamayo, La Merced, 9 km from Oroya, approximately 2500 ft (=762 m) elevation, CAS 69135, 19 (5, 67.0–72.4). Provincia Chanchamayo, San Ramón, Quebrada Inia, MUSM 5915, 4 (1, 43.3), MUSM 5916, 1. Provincia Chanchamayo, Santa Ana, Río Santa Ana, MUSM 5917, 2. Provincia Satipo, Mazamari, Río Mazamari, on highway to San Martin de Pongao (11°21′S, 74°34′W), MUSM 5241, 6 (5, 55.0–74.3).