Creagrutus veruina Vari & Harold 2001

Creagrutus veruina

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, 5 teeth in the primary series of each premaxilla, 2 or 3 maxillary teeth, 4 teeth on each dentary, 9 predorsal median scales, 39 lateral line scales without a lamellar process over each pore, 4 scale rows between the dorsal-fin origin and the lateral line, 2 scale rows between the anal-fin origin and the lateral line, 11 branched anal-fin rays, 5 or 6 gill rakers on the upper limb of the first gill arch and 10 or 11 gill rakers on the lower limb of the first gill arch, 37 or 38 vertebrae, the distance from the dorsal-fin origin to the anal-fin origin (24.6%–25.3% of SL), the distance from the dorsal-fin origin to the pelvic-fin insertion (18.7%–20.2% of SL), the distance from the dorsal-fin origin to the pectoral-fin insertion (28.9%–30.2% of SL), the caudal peduncle depth (9.2%–9.4% of SL), the pectoral-fin length (16.9%–17.5% of SL), the pelvic-fin length (12.8%–13.5% of SL), the dorsal-fin length (17.2%–18.0% of SL), the anal-fin length (12.8%–14.6% of SL), the postorbital head length (38.6%–41.9% of HL), the snout length (30.8%–32.1% of HL), the interorbital width (24.8%–26.8% of HL), the near contact of the ventral margin of the third infraorbital with the horizontal limb of the preopercle in larger specimens, the absence of a distinct spot of dark pigmentation at the base of the middle caudal-fin rays, the vertically elongate humeral mark without a secondary, dorsal patch of pigmentation, the absence of a distinct patch of pigmentation on the dorsal fin, and the absence of a series of dark spots along the midlateral surface of the body distinguishes Creagrutus veruina within the clade formed by Creagrutus and Piabina.

DESCRIPTION.—Morphometric and meristic data for Creagrutus veruina in Table 56. Head and body relatively elongate, more so in smaller individuals. Greatest body depth at dorsal-fin origin in most individuals of all sizes, shifted anteriorly in one specimen with distended abdomen. Dorsal profile of head convex from margin of upper lip to vertical through anterior margin of eye, convexity slightly more pronounced in smaller individuals; convex from vertical through anterior margin of eye to tip of supraoccipital spine in smaller specimens, barely convex or straight in that region in larger individuals. Interorbital region transversely convex; convexity more pronounced in smaller specimens. Dorsal profile of body nearly straight from tip of supraoccipital spine to dorsal-fin origin, without change in alignment relative to dorsal profile of head. Dorsal surface of body with obtuse median keel proximate to dorsal-fin origin. Ventral profile of head with obtuse angle at anteroventral corner of dentary; straight or slightly convex from that point to isthmus Profile of prepelvic portion of body typically straight, convex in specimen with distended abdomen. Prepeivic region of body obtusely flattened transversely in larger individuals.

Characters A B

Morphometrics

Standard length 44.7 26.9–41.1

1. Snout to anal-fin origin 62.1 61.6–62.0

2. Snout to pelvic-fin insertion 45.9 45.7–47.0

3. Snout to pectoral-fin insertion 22.6 23.0–24.1

4. Snout to dorsal-fin origin 44.7 45.0–47.0

5. Dorsal-fin origin to hypural joint 55.3 56.1–57.9

6. Dorsal-fin origin to anal-fin origin 24.8 24.6–25.3

7. Dorsal-fin origin to pelvic-fin insertion 19.0 18.7–20.2

8. Dorsal-fin origin to pectoral-fin insertion 30.2 28.9–30.1

9. Caudal peduncle depth 9.4 9.2–9.4

10. Pectoral-fin length 17.5 16.9–17.5

11. Pelvic-fin length 13.0 12.8–13.5

12. Dorsal-fin length 17.2 17.4–18.0

13. Anal-fin length 12.8 13.2–14.6

14. Head length 26.2 26.0–26.5

15. Postorbital head length 41.9 38.6–40.9

16. Snout length 30.8 31.2–32.1

17. Bony orbital diameter 35.9 34.9–36.1

18. Interorbital width 24.8 25.0–26.8

Meristics

Lateral line scales 39 39a,b

Scale rows between dorsal-fin origin and lateral line 4 4a,c

Scale rows between anal-fin origin and lateral line 2 2c

Predorsal median scales 9 9c

Branched dorsal-fin rays 8 8c

Branched anal-fin rays 11 11c

Branched pelvic-fin rays 7 6–7c

Pectoral-fin rays 13 13c

Vertebrae 38 37–38d

Head obtusely pointed in both lateral and dorsal views. Upper jaw longer than, and overhanging, lower jaw. Papillae present on anteromedial portions of snout, but more concentrated on upper lip and on folds and plicae extending between outer and medial premaxillary teeth; papillae well developed on anteroventral portion of lower jaw, more concentrated on margin of lower lip. Orbit ovoid and slightly longer along its anteroposterior axis.

Infraorbital series moderately developed. Third infraorbital with posteroventral margin rounded; ventral margin distinctly separated from horizontal limb of preopercle in smaller specimens, anteroventral margin of bone approaching horizontal limb of preopercle in larger specimens. Posterior margin of third through fifth infraorbitals falling short of vertical limb of preopercle; gap progressively decreasing dorsally.

Premaxillary dentition in three series: primary series with 5 teeth arranged in slightly sigmoid pattern, teeth without pronounced gap between first and second tooth of series but with medial tooth separated from contralateral series by distinct gap, 3 anterior teeth unicuspidate with tips posteriorly recurved and fourth and fifth teeth with poorly developed lateral cusps; triangular cluster of 3 larger teeth with anterior tooth unicuspidate with slight lateral expansions in positions typically occupied by lateral cusps, and two posterior teeth with weak lateral cusps; and single unicuspidate tooth occurring lateral to third tooth of primary premaxillary row. Maxilla with 2 or 3 tricuspidate teeth. Dentary teeth difficult to examine because of lack of cleared and stained specimens; apparently 4 dentary teeth with first three teeth distinctly larger than fourth tooth; second tooth somewhat higher and wider than first tooth and distinctly larger than third tooth.

Dorsal-fin rays ii,8 in all examined specimens. Dorsal-fin origin slightly posterior to vertical through pelvic-fin insertion. Profile of distal margin of dorsal fin slightly concave. Anal-fin rays ii,11 in all specimens. Profile of distal margin of anal fin concave. Anal-fin hooks present in mature males of many Creagrutus species not apparent in limited available population sample. Pectoral-fin rays i,12. Tip of pectoral fin reaching posteriorly approximately three-fourths of distance to pelvic-fin insertion. Pelvic-fin rays i,6 or 7 in holotype and paratypes; count cannot be determined in nontypes. Tip of pelvic fin reaching posteriorly to within 2 scales of anal-fin insertion. Anal-fin hooks present in mature males of many Creagrutus species not apparent in examined material.

Gill rakers 5–6 + 0–11.

COLORATION IN ALCOHOL.—Ground coloration light tan. Dorsal surface of head with stellate, dark chromatophores overlying brain in smaller specimens, chromatophores relatively smaller and partially obscured by intracranial adipose deposits in larger individuals. Surface of head with scattered chromatophores in larger individuals. Chromatophores somewhat more concentrated anterior to nares, but not forming dark, crescent-shaped patch of pigmentation present in that area in many congeners. Region anteroventral to nares with few chromatophores, but these not forming distinct stripe present in that region in many Creagrutus species. Dorsal portions of both infraorbital series and opercle with scattered chromatophores in smaller individuals, chromatophore field more concentrated in larger specimens.

Dorsalmost series of body scales in larger specimens outlined with dark chromatophores. Smaller individuals (18.6–21.4 mm SL) with a few scattered chromatophores in region of humeral mark; large individuals with vertically elongate humeral mark. Humeral mark ventrally attenuate and most intensely pigmented immediately dorsal to lateral line, somewhat expanded and anteriorly arching dorsally. Larger specimens with diffuse, dark pigmentation along midlateral portion of body. Caudal-fin base with diffuse vertical line of deep-lying pigmentation in smaller individuals, pigmentation masked in larger specimens. Distal portions of dorsal and anal fins with scattered chromatophores in larger specimens. Rays of dorsal and ventral portions of caudal fin outlined with small, dark chromatophores in larger specimens that also have dusky middle caudal-fin rays. Pectoral and pelvic fins hyaline.

COMPARISONS.—Creagrutus veruina shares similar dentition and overall body form with C. runa, which is endemic to the upper Rio Negro of the Amazon basin. The two species can be distinguished by differences in the number of branched anal-fin rays (11 in C. veruina versus 9 or 10 in C. runa), differences in the form of the humeral mark (compare Figures 85 and 91), the distance from the snout to the anal-fin origin (61.6%–62.1% of SL in C. veruina versus 64.4%–68.8% of SL in C. runa), and the distance from the snout to the pectoral-fin insertion (22.6%–24.1% of SL in C. veruina versus 24.3%–27.2% of SL in C. runa).

The only other species of Creagrutus known from the Río Cataniapo basin is C. provenzanoi, which was collected at various localities in that basin. The species are apparently syntopic, at least to a degree, because a paratype of C. provenzanoi was captured along with the type series of C. veruina. Creagrutus veruina can be distinguished from C. provenzanoi by the form of the humeral mark (bar-like in C. veruina versus expanded and rounded immediately above lateral line in C. provenzanoi), the number of scales below the lateral line to the anal-fin origin (2 versus 3, respectively), and various morphometric features (compare Tables 51 and 56).

ETYMOLOGY.—The species name, veruina, from the Latin for small javelin, refers to the elongate overall form of the species.

ECOLOGY.—One of the nontype species of Creagrutus veruina was captured in moderate to swift current over a rock and mud bottom with submerged vegetation.

DISTRIBUTION.—Creagrutus veruina is known only from the Río Cataniapo, an east bank tributary of the middle Río Orinoco is southern Venezuela (Figure 90, open star).

MATERIAL EXAMINED.—25 specimens (5, 26.8–44.7; only meristics taken on some of the nontype specimens as a consequence of their condition; see under “Remarks,” above).

HOLOTYPE.—VENEZUELA. Amazonas: Río Cataniapo, 200 m above Las Pavas, collected by R. Royero et al., 24 Dec 1983, MBUCV V-29072, 1 (44.7).

PARATYPES.—4 specimens (4, 26.8–41.1).

VENEZUELA. Amazonas: Río Cataniapo, 200 m above Las Pavas, collected with holotype, MBUCV V-14638, 2 (2, 26.9–41.1); USNM 355120, 2 (26.8–30.8).

NONTYPE SPECIMENS.—20 specimens.

VENEZUELA. Amazonas: Río Cataniapo, Caño Carinagua, MCNG 7613, 16. Río Cataniapo, approximately 3.0 km S of Puerto Ayacucho (5°35′N, 67°35′W), ANSP 165531, 1. Río Cataniapo, at bridge on Puerto Ayacucho-Samariapo highway, approximately 3.0 km S of Puerto Ayacucho (5°32′N, 67°31′W), ANSP 159829, 3.