Creagrutus gyrospilus Vari & Harold 2001

Creagrutus gyrospilus

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, 6 teeth in the primary series of each premaxilla, 3 or 4, rarely 2, maxillary teeth, 5 or 6 teeth on each dentary, 10 to 12 median predorsal scales, 36 to 39 lateral line scales without a lamellar process over each pore, usually 4 scale rows between the dorsal-fin origin and the lateral line, 2 post-anal scales to the anal-fin origin, 3 scale rows between the anal-fin origin and lateral line, usually 10 or 11 branched anal-fin rays, 5 to 8 gill rakers on the upper limb and 9 to 11 gill rakers on the lower limb of the first gill arch, 35 to 37 vertebrae, the caudal peduncle depth (11.3%–13.2% of SL), the postorbital length (45.0%–50.6% of HL), the bony diameter (25.8%–32.7% of HL), the interorbital width (29.1%–34.7% of HL), the contact, or near contact, of the ventral margin of the third infraorbital and the horizontal limb of the preopercle, the lack of a distinct spot of dark pigmentation at the base of the middle caudal-fin rays, the vertically rotund humeral mark without a secondary, dorsal patch of pigmentation, the absence of a distinct patch of pigmentation on the dorsal fin, and the lack of a series of dark spots along the midlateral surface of the body distinguishes Creagrutus gyrospilus within the clade formed by Creagrutus and Piabina.

DESCRIPTION.—Morphometric and meristic data for Creagrutus gyrospilus in Table 22. Body relatively deep and compressed. Greatest body depth within one or two scale rows anterior of base of anteriormost dorsal-fin ray. Dorsal profile of head distinctly convex from margin of upper lip to vertical through posterior margin of anterior nares; straight from that point to posterior tip of supraocciptal spine; smoothly convex from that point posteriorly to anterior of dorsal-fin base, or with inflection point or slight hump two to three scale rows posterior of supraoccipital. Profile of body straight and slightly inclined along dorsal-fin base, straight to slightly convex from base of posterior dorsal-fin ray to anterior procurrent caudal-fin ray, with slight dorsal inflection comprising sheath scales at adipose-fin base. Ventral profile of head with broadly rounded obtuse angle approximately midway between margin of lower lip and posterior extremity of dentary, slightly convex from that point to isthmus. Ventral profile of body slightly curved from isthmus to pelvic-fin insertion; then concave from anteriormost anal-fin ray to anterior ventral procurrent caudal-fin ray.

Anterior profile of head rounded in lateral view. Upper jaw longer than, and overhanging, lower jaw by distance about equal to up to one-half of orbital diameter. Anterior portion of snout relatively soft and fleshy, with concentration of soft tissues; minute papillae concentrated on snout and upper lip, continuing into mouth on fleshy flaps and plicae extending between outer and medial premaxillary teeth. Lower jaw distinctly fleshy anteriorly, with concentrated papillae. Inner surfaces of lower lip convolute and papillose, with fleshy flaps extending into mouth. Concentrations of papillae also present over lower jaw, isthmus, and cheek.

Elements of infraorbital series somewhat reduced, with ventral margin of third infraorbital usually contacting, or nearly contacting, ventral limb of preopercle. Posterior and posteroventral margins of third infraorbital separated from vertical limb of preopercle by gap equal to at most one-half width of third infraorbital; posterior and posteroventral margin of infraorbital series describing broad arc approximately concentric with margin of orbit.

Premaxillary teeth in three distinct series: primary series arched, with 6 weakly tricuspidate teeth, without pronounced gap between first and second of series, lateral cusps of anterior 4 teeth usually indistinct; triangular cluster of 3 large tricuspidate teeth, posterior 2 teeth largest and with most highly developed cusps; and single outer weakly tricuspidate tooth positioned approximately lateral to fourth tooth in primary premaxillary series. Maxilla usually with 3 or 4, rarely 2, tricuspidate teeth. Dentary with 5 or 6 unicuspidate or tricuspidate teeth; anterior two teeth largest and with most highly developed secondary cusps, third tooth smaller than first two teeth, with cusps less prominent; 2 or 3 posteriormost teeth relatively small, with weakly developed cusps.

Dorsal-fin rays ii,8 in most individuals, ii,9 in one nontype specimen. Dorsal-fin origin at, or slightly posterior of, vertical through pelvic-fin origin. Distal margin of dorsal fin slightly concave as result of elongation of second unbranched ray, anterior three branched rays, and posterior two branched rays. Anal-fin rays ii-iii,9–11; 9 branched rays less common. Anal- fin hooks, when present, occurring on anteriormost 2 or 3 branched rays. Distal margin of anal fin slightly sigmoidal, with second unbranched and anterior 3 branched rays forming variously developed slightly elongate lobe, outline of posterior 5 or 6 branched rays concave. Pectoral-fin rays i, 10–12, 12 branched rays less common. Pectoral fin short in some individuals, reaching to within two scale rows of pelvic-fin origin, longer in presumptive males (as indicated by presence of pelvic- and anal-fin ray hooks) and reaching to, or nearly reaching, pelvic-fin base. Pelvic-fin rays i,6,i or i,7. Pelvic-fin hooks, when present, located on medial surfaces of segmented and unsegmented portions of main shaft and medial and branches of all rays medial of the lateral unbranched element; additional weak hooks present on medial surfaces of lateral secondary branches of medial 3 or 4 rays. Tip of pelvic fin not reaching anal-fin origin in males (as indicated by presence of pelvic- and anal-fin ray hooks); in other specimens tip of pelvic fin reaching within 1 or 2 scale rows of that point. Scales on posterior margin of body generally smoothly rounded.

Gill rakers 5–8 + 9–11.

COLORATION IN ALCOHOL.—Overall pigmentation dusky, with well-developed dark humeral spot and lateral stripe; ground color light brown, with chromatophores ranging from dark brown over much of body to nearly black in areas of higher concentration. Dorsal surface of head with high concentration of small, dark brown, punctate chromatophores, chromatophores most concentrated over snout and medial portions of upper lip, including vertical crescent-shaped area immediately anterior of anterior nares. Pigmentation continuing posteriorly across interorbital area, covering frontal fontanel. Patch of scattered, dark chromatophores extending laterally from snout along dorsal portion of maxilla. Dorsal surface of parietal portions of cranium and area immediately dorsal of eye pigmented with scattered, relatively large, dark brown, stellate chromatophores. Band of small, dark brown chromatophores extending from immediately lateral of nares posteroventrally and continuing around ventral and posterior margins of orbit. Dark, stellate chromatophores scattered over dorsal half of opercle in region posterior to orbit. Lower lip and ventrolateral surface of head unpigmented.

Body pigmentation most concentrated in region dorsal of lateral line; pigmentation in form of broad vertical crescents in association with anteriormost exposed portion of each scale. Scattered, very dark chromatophores present along dorsal midline, especially well developed along anterior half of predorsal area, in region immediately lateral of dorsal-fin base, and along middorsal area between dorsal and adipose fins. Humeral mark rounded to somewhat vertically ovoid blotch located in lateral line scale row and scale row immediately dorsal to it. Pigmentation on lateral surface of body ventral to lateral line, other than for that associated with humeral spot, mostly restricted to small, dark chromatophores delineating hypaxial myosepta immediately dorsal of anal-fin base. Midlateral body stripe relatively diffuse anteriorly, becoming denser and somewhat wider approximately at vertical through dorsal-fin origin and extending well ventral of lateral line and posteriorly onto caudal peduncle. Intensity of midlateral stripe pigmentation greatest in region from directly ventral of dorsal fin posteriorly to area overlying hypurals.

Dorsal-fin membranes with small number of moderately dark chromatophores associated with distal one-half of second unbranched and anterior 5 or 6 branched rays; basal portions of shafts of all, or nearly all, fin rays with scattered, dark chromatophores. Anal fin mostly unpigmented, with dark chromatophores located along bases of each ray along approximately anterior one-half of its length. Small, nearly black chromatophores scattered over distal portions of anal-fin ray membranes. Caudal-fin rays delineated by small, dark chromatophores, with greatest concentrations along dorsalmost rays and over much of ventral lobe. Darkest caudal-fin pigmentation confined to proximal portions of central 4 branched rays, appearing as small, interrupted, slightly horizontally elongate dark spot. Pectoral-fin pigmentation confined to dark line of chromatophores along lateral unbranched ray and in association with up to four adjacent branched rays. Pelvic fin hyaline.

ETYMOLOGY.—The specific name, gyrospilus, from the Latin gyro, meaning circular, and spilus, meaning spot, in reference to the form of the humeral spot in the species.

ECOLOGY.—The type locality (INHS 69479, INHS 51282, and USNM 359486) and the locality from which the nontype specimens (INHS 61329) originated were both clear rocky streams with considerable current.

DISTRIBUTION.—Creagrutus gyrospilus is known only from two localities in the western portions of the Río Orinoco basin (Figure 43, solid stars).

COMPARISONS.—Creagrutus gyrospilus is most similar to the sympatric C. taphorni with respect to body shape, meristic character values, and the relative development of the infraorbital series. The two species differ, however, in the form of the humeral mark (compare Figures 45 and 88). Other similar species, occurring in other drainage systems, include C. crenatus and C. lassoi, which have vertically elongate humeral marks contrary to the rounded mark in C. gyrospilus. These species also differ in various meristic and morphometric features.

MATERIAL EXAMINED.—77 specimens (44, 44.4–62.3).

HOLOTYPE.—VENEZUELA. Portuguesa: Río Saguaz, Río Guanare-Apure drainage, bridge near park on road to Chabasquén (=Paraíso de Chabasquén; 9°23′30″N, 70°00′30″W), collected by D.C. Taphorn et al., 16 Jan 1986, INHS 69479, 1 (47.7; male).

PARATYPES.—40 specimens (40, 44.4–62.3).

VENEZUELA. Portuguesa: Río Saguaz, Río Guanare-Apure drainage, bridge near park on road to Chabasquen (=Paraíso de Chabasquén; 9°23′30″N, 70°00′30″W), collected with holotype, INHS 51282, 32 (48.6–62.3); USNM 359486, 8 (44.4–61.6).

NONTYPE SPECIMENS.—36 specimens (3, 46.3–60.0).

VENEZUELA. Barinas: Tributary of Río Santo Domingo, Río Apure drainage, 10 km NW Barinitas (latter locality at 8°45′N, 70°45′W), INHS 61329, 6 (3, 46.3–60.0). Lara: Río Claro, in town of Río Claro (9°55′30″N, 69°21′20″W), MCNG 13392, 30.

Creagrutus gyrospilus, INHS 51282, 2, 51.9–55.8 mm, paratypes; Venezuela, Portuguesa, Río Saguaz

Creagrutus hildebrandi, USNM 121487, 1, 43.2 mm, paratype; Venezuela, Río Palmar near Totuma. USNM 121484, 2, 26.7–40.5 mm, paratypes; Venezuela, Río San Juan.

Creagrutus holmi, USNM 167816, 3 (AR), 39.4–57.8 mm; Peru, Cajamarca, Balsas. USNM 341368, 1, 55.4 mm, paratype; Peru, Amazonas, Río Marañon basin, Bagua Grande.

Creagrutus hysginus, USNM 326035, 2, 36.1–42.7 mm, paratypes; USNM 326055, 2, 39.5–41.3 mm, paratypes; MBUCV-V 20304, 1, 38.0 mm, paratype; Venezuela, Sucre, Río La Toma. CAS 79623, 1, 41.3 mm, paratype; Venezuela, Sucre, Río Güiria.