Creagrutus kunturus Vari, Harold & Ortega 1995

Dorsal soft rays (total): 9 - 11; Analsoft rays: 13 - 16; Vertebrae: 38 - 41

Creagrutus kunturus, USNM 335147, 1, 68.6 mm, paratype; Peru, Amazonas, Río Comainas basin

Creagrutus lassoi, MCNG 24685, 2, 41.9–57.6 mm; Venezuela, Yaracuy, Río Tupe, N of Aroa.

Creagrutus kunturus Vari et al., 1995:290, figs. 1, 2

DIAGNOSIS.—The combination of the possession of premaxillary dentition arranged in the three components generalized for most of the species of Creagrutus and Piabina without a distinctly larger gap between the first and second teeth of the primary series, 2 or 3 teeth on the maxilla, 6, rarely 5, teeth in the primary tooth row of the premaxilla, 5 or 6 dentary teeth, 39 to 43 lateral line scales without a lamellar process over each pore, 12 predorsal median scales, 38 to 41 vertebrae, 11 to 13 branched anal-fin rays, 1 post-anal median scale to the anal-fin origin, 9 to 11 gill rakers on the lower limb of the first gill arch, the absence of a discrete secondary component dorsal to the main body of the humeral mark, the possession of a series of dark spots along the midlateral surface of the body that ontogenetically coalesce in variable patterns, sometimes resulting in a solid dark stripe in larger individuals, and the absence of a discrete patch of dark pigmentation on the middle portion of the anterior dorsal-fin rays distinguishes Creagrutus kunturus from all species within the clade composed of Creagrutus and Piabina with the exception of C. amoenus. Creagrutus kunturus can be separated from C. amoenus by the combination of the number of lateral line scales (39–43, rarely 39, in C. kunturus versus 35–39, rarely 39, in C. amoenus), total vertebrae (38–41, typically 39 or 40, in C. kunturus versus 36–39, rarely 39, in C. amoenus), the depth of the caudal peduncle (11.1%–12.1% of SL in C. kunturus versus 12.2%–13.8% of SL in C. amoenus), and the distance from the dorsal-fin origin to the anal-fin origin (30.8%–34.0% of SL in C. kunturus versus 33.8%–38.8% of SL in C. amoenus).

DESCRIPTION.—Morphometric and meristic data for Creagrutus kunturus in Table 26. Head and anterior portion of body relatively robust; region of body posterior of vertical through anal-fin origin more slender. Greatest body depth at, or slightly anterior of, vertical through dorsal-fin origin. Dorsal profile of head from tip of snout to rear of supraoccipital spine smoothly convex, some specimens with profile disrupted by irregular processes in region above nares. Interorbital region distinctly convex transversely. Predorsal profile of body slightly convex, with variably evident inflection of profile of head at rear of supraoccipital spine (compare Figures 49 and 50). Ventral profile of head in many individuals with obtuse angle at anteroventral corner of dentary, gently curved from that region to isthmus. Ventral profile of body convex to anal-fin origin and slightly concave from anal-fin insertion to caudal fin.

Characters A B

Morphometrics

Standard length 84.1 53.2–96.0

1. Snout to anal-fin origin 64.8 61.4–65.3

2. Snout to pelvic-fin insertion 46.6 44.2–49.1

3. Snout to pectoral-fin insertion 24.6 22.3–28.0

4. Snout to dorsal-fin origin 47.3 45.5–50.5

5. Dorsal-fin origin to hypural joint 56.2 53.9–60.3

6. Dorsal-fin origin to anal-fin origin 33.5 30.8–34.0

7. Dorsal-fin origin to pelvic-fin insertion 28.7 27.9–31.6

8. Dorsal-fin origin to pectoral-fin insertion 33.0 32.2–35.1

9. Caudal peduncle depth 11.4 11.1–12.1

10. Pectoral-fin length 20.9 18.6–21.9

11. Pelvic-fin length 15.3 14.7–17.2

12. Dorsal-fin length 20.7 20.1–24.8

13. Anal-fin length 15.8 15.4–19.0

14. Head length 25.1 24.2–29.1

15. Postorbital head length 44.3 40.9–47.1

16. Snout length 28.1 27.3–32.3

17. Bony orbital diameter 28.1 26.7–32.5

18. Interorbital width 28.1 24.9–31.2

Meristics

Lateral line scales 41 39–43

Scale rows between dorsal-fin origin and lateral line 5 4–5

Scale rows between anal-fin origin and lateral line 4 3–4

Predorsal median scales 12 12

Branched dorsal-fin rays 8 7–8

Branched anal-fin rays 12 11–13

Branched pelvic-fin rays 7 6–7

Pectoral-fin rays 13 12–14

Vertebrae 39 38–41

Head obtusely pointed in lateral view and distinctly pointed in dorsal view. Upper jaw distinctly longer than, and overhanging, lower jaw. Anterior portion of snout fleshy, with scattered papillae. Papilla more concentrated along ventral margin of upper lip and on fleshy folds and plicae extending between outer and medial premaxillary teeth. Lower lip fleshy anteriorly with papillae along dorsal margin.

Infraorbital series moderately developed. Central portion of ventral margin of third infraorbital contacting horizontal limb of preopercle. Posterior margins of third through fifth infraorbitals distinctly separated from vertical limb of preopercle, gap decreasing gradually dorsally.

Premaxillary dentition in three series: primary row slightly curved, typically with 6 teeth, 5 teeth present on both premaxillae in one specimen and 7 teeth on one premaxilla in one specimen, without pronounced gap between first and second tooth of series but with anteromedial tooth separated from contralateral equivalent by distinct gap filled by fleshy fold; triangular cluster of 3 larger teeth lying medial to primary row; and single tooth of form similar to that of primary series occurring lateral to fourth tooth of primary premaxillary row. Maxilla with 2 or 3 tricuspidate teeth. Dentary with 5 or 6 tricuspidate teeth; first and second dentary teeth distinctly larger than remaining teeth and subequal, approximately 1.7 times height of third tooth; fourth through fifth or sixth teeth distinctly smaller and compressed.

Dorsal-fin rays typically ii,8, rarely iii,8 or ii,7. Dorsal-fin origin ranging from anterior of, to posterior to, vertical through pelvic-fin insertion. Profile of distal margin of dorsal fin straight to very slightly concave. Anal-fin rays ii,11–13 or iii,11–13. Profile of distal margin of anal fin straight. Hooks typically present on anal-fin rays in mature males of many Creagrutus species not found in examined specimens. Pectoral-fin rays i,11–13. Relative length of pectoral fin somewhat variable, ranging from falling slightly short of vertical through pelvic-fin insertion to extending to beyond that line. Pelvic-fin rays i,6,i or i,7 with higher number of branched rays typical of larger individuals. Tip of pelvic fin extending posteriorly to, or falling slightly short of, anus. Hooks typically present on pelvic-fin rays in mature males of many Creagrutus species not found in examined specimens.

Gill rakers 7–8 + 9–11.

COLORATION IN ALCOHOL.—Overall ground coloration of relatively freshly collected specimens light tan. Dorsal surface of head with dense field of small dark chromatophores, giving the region distinctly dusky appearance. Intensity of dark pigmentation more noticeable over brain, presumably as consequence of deep-lying pigmentation overlying membranes of that organ in most Creagrutus species. Dense surface pigmentation continuing anteriorly over snout and upper lip. Crescent-shaped patch of denser pigmentation anterior to nares obvious in smaller specimens; not distinct from remaining dark pigmentation anterior to orbit in larger individuals. Regions immediately ventral and posterior to orbit with pigmentation field interrupted by unpigmented laterosensory canal segments. Lower portion of cheek lacking dark chromatophores in all but largest individuals, which have scattered chromatophores in that region. Variably developed pattern of dark pigmentation posterior to orbit; pigmentation ranging in form from diffuse, irregular band, through overall diffuse band, to vertically elongate spot overlying portion of preopercle and margins of fourth and fifth infraorbitals, to distinct band with irregular dorsal and ventral borders extending from rear margin of orbit to rear margin of opercle.

Scales of dorsal portion of body with small dark chromatophores concentrated along posterior scale margin, forming overall reticulate pattern. Humeral mark vertically elongate, with most intensely pigmented region centered immediately dorsal of lateral line. Small ventrally attenuating, less densely pigmented region extending ventrally from main body of humeral mark as far as one scale row ventral of lateral line. Distinct, anteriorly concave, more diffuse area of dark pigmentation extending approximately two scale rows anterodorsally from dorsal margin of region of darkest pigmentation. Midlateral body pigmentation highly variable both ontogenetically and between comparably sized individuals, formed of two components: band of dark deep-lying chromatophores and overlying patches of dark surface pigmentation. Surface pigmentation ranging from discrete, widely separated spots of approximately size of pupil of eye, through variously coalesced spots, to nearly continuous dark band extending from near posterior margin of humeral mark posteriorly to base of middle caudal-fin rays.

Dorsal fin with membranes and margins of fin rays with small dark chromatophores, particularly on distal two-thirds of fin; intensity of pigmentation increasing ontogenetically. Basal portions of anal-fin rays outlined by small dark chromatophores in medium-sized individuals, rays nearly completely outlined in larger specimens. Caudal fin with rays and membranes with associated small dark chromatophores, particularly in larger individuals. Distinct band of dark pigmentation on middle caudal-fin rays; band most intense basally. Pelvic and pectoral fins nearly hyaline in smaller individuals, dusky in larger specimens.

ECOLOGY.—The collecting localities of the holotype and paratype series are at an altitude of 850–900 m, along the Cordillera del Condor. In that region the Río Comainas is shallow with clear water for most of the year, but it becomes torrential with white waters during, and after, heavy rains. The river varies from 8 to 20 m in width, with the main channel during low water periods being 30 to 190 cm deep over a bottom of rocks, pebbles, sand, and clay. The nontype specimens collected at Chigkan entse (=Quebrada Chigkan) (LACM 39681-1) also came from a relatively shallow stream approximately 4 m wide with moderate current. The single specimen cleared and counterstained, which was collected during late July, had very well-developed testes and had fed on larval and adult insects.

DISTRIBUTION.—Creagrutus kunturus is distributed through the upper Río Marañon in northeastern Peru and through the upper Río Pastaza to the southwestern portion of Río Napo in southeastern Ecuador (Figure 51, dots).

COMPARISONS.—Creagrutus amoenus, a species very similar to C. kunturus (see “Diagnosis,” above), also occurs in the Río Pastaza and Río Napo basins, but the two species are not known to be syntopic. In both the Río Pastaza and Río Napo basins and throughout its range, C. amoenus occurs in regions of somewhat lower altitude than does C. kunturus (compare Figures 22 and 51).

MATERIAL EXAMINED.—43 specimens (31, 53.2–96.0).

PERU. Amazonas: Provincia Condorcanqui, Cordillera del Condor, upper Río Comainas, 20 m upriver of Puesto de Vigilancia No. 22 (3°56′30″S, 78°24′20″W), MUSM 5667, 1 (84.1, holotype of Creagrutus kunturus); MUSM 6593, 1 (77.5, paratype of Creagrutus kunturus); USNM 335146, 1 (82.3, paratype of Creagrutus kunturus). Provincia Condorcanqui, Cordillera del Condor, Quebrada no. 1, tributary of Río Comainas, PV 22, MUSM 5669, 3 (62.2–64.5). Provincia Condorcanqui, Cordillera del Condor, Río Comainas, 30 m down river of Puesto de Vigilancia No. 22 (3°56′30″S, 78°24′20″W), MUSM 5665, 2 (57.3–58.0, paratypes of Creagrutus kunturus); USNM 335148, 2 (63.8–65.3, paratypes of Creagrutus kunturus). Provincia Condorcanqui, Cordillera del Condor, Río Comainas, 40 m upriver of Puesto de Vigilancia No. 22 (3°56′30″S, 78°24′20″W), MUSM 5663, 1 (90.3, paratype of Creagrutus kunturus). Provincia Condorcanqui, Cordillera del Condor, Quebrada no. 3, tributary of Río Comainas, Puesto de Vigilancia No. 22 (3°56′30″S, 78°24′20″W), MUSM 5668, 2 (64.2–75.6, paratypes of Creagrutus kunturus); USNM 335147, 2 (64.3–68.6, paratypes of Creagrutus kunturus; 1 specimen cleared and counterstained for cartilage and bone). Río Cenepa, Chigkan entse (=Quebrada Chigkan) tributary to Río Cenepa (4°28′S, 78°10′W), LACM 39681-1, 3 (72.0–92.0). Río Alto Comainas, vicinity of Shaim (04°15′S, 78°22′W), LACM 39686-15, 1.

ECUADOR. Pastaza: Río Alpayacu, 1 km E of Mera (1°28′S, 78°07′W); KU 19977, 3 (65.5–82.5). Upper portion of Río Arajuno, few km NE of El Puyo, Río Napo basin (approximately 1°24–26′S, 77°50–55′W), USNM 164066, 2 (75.2–96.0); 96.0); ANSP 75911, 1. Río Pundo Grande, Puyo, MEPN 9838, 1. Río Conambo, at the settlement of Moretecocha (0°36′S, 77°24′W), MEPN 4635, 11 (8, 53.2–71.4); USNM 340956, 6.