Geophagus abalios , López-Fernández, Hernán & Taphorn, Donald C., 2004
treatment provided by
Geophagus abalios n. sp.
( Figs. 2 View Figure b, 3–5, 9)
Holotype. MCNGAbout MCNG 47600, 163.0 mm SL; Venezuela: Apure: Río Cinaruco: Laguna Larga (6.5339 N 67.4150 W); K. Winemiller, H. LópezFernández, D.A. Arrington, L. Kelso Winemiller, H. LópezChirico and J. Arrington, 13 Jan 1999.
Paratypes. MCNGAbout MCNG 30939, 3, 86.0–115.0 mm SL; Venezuela: Anzoátegui: Río Orinoco: Laguna Tineo (8.1903°N 63.4722°W); M.A. Rodríguez, 0 4 April 1987. — MCNGAbout MCNG 33723, 3, 54.3–132.0; Venezuela: Bolívar: Río Orinoco: Laguna Bartolico (7.6417°N 66.1167°W); M.A. Rodríguez, 13 Jan 1987. — MCNGAbout MCNG 35035, 1, 74.4 mm SL; Venezuela: Amazonas: Río Casiquiare: Playa Macanilla (2.4331 N 66.4547 W); K. O. Winemiller and D. Jepsen, 31 Jan 1997. — MCNGAbout MCNG 40878, 1, 112.1 mm SL; Venezuela: Apure: Río Cinaruco: Laguna Guayaba; D.A. Arrington and J. Arrington, 12 April 1999. — MCNGAbout MCNG 41124, 2, 45.5–55.5 mm SL; Venezuela: Apure: Río Cinaruco; D.A. Arrington and J. Arrington 14 April 1999. — AMNHAbout AMNH 233634 (exMCNG 44865), 1, 96.3 mm SL; Venezuela: Apure: Río Cinaruco (6.5333 N 67.4164 W); D.A. Arrington and J.A. Arrington, 16 March 1999. — MCNGAbout MCNG 47602 (exMCNG 6278), 1, 151.0 mm SL; Venezuela: Apure: Rio Cinaruco: Hato Las Delicias (6.5750°N 67.2361°W); D.C. Taphorn, C. Lilyestrom and B. Stergios, 11 Jan 1982. — MCNGAbout MCNG 47601, 2, 96.3–160.0 mm SL; collected with holotype. — AMNHAbout AMNH 93052, 2, 132.9–150.0 mm SL; Venezuela: Amazonas: Río Mavaca: small tributary on left bank; C.J. Ferraris and R. Royero, 10 March 1989.
Diagnosis. The lack of head markings distinguishes G. abalios n. sp. from Geophagus grammepareius , G. taeniopareius , G. harreri and G. argyrostictus , which have a complete infraorbital stripe, and from G. dicrozoster n. sp., G. winemilleri n. sp., G. brachybranchus and G. proximus , which have a black preopercular marking. Preserved specimens of Geophagus abalios can be distinguished from all other Geophagus species without head markings except G. brokopondo by the possession of six vertical, parallel bars on the flank ( Fig. 1 View Figure , 2 View Figure ); it can be distinguished from G. brokopondo by the anterior three bars, which are medially bisected by a clearer area, giving the impression of two thinner bars, whereas in the latter species all bars are solid; additionally, the sixth bar in G. abalios is elongate and restricted to the dorsal half of the caudal peduncle, above the lower lateral line, and in G. brokopondo the line covers the entire caudal peduncle ( Fig. 2 View Figure b and 2 d).
Description. Based on holotype (163.0 mm SL) and 16 paratypes 45.5–192.0 mm SL with notes on variation among smaller specimens. Measurements and counts are summarized in Table 1. Sexes appear to be isomorphic.
Shape. Moderately elongate; dorsal outline more convex than ventral outline; head slightly broader ventrally than dorsally, chest flat; specimens 45.0 mm SL and smaller more elongate, with rounder nape; interorbital area moderately concave. Dorsal head profile straight, slightly concave in front of orbit, straight or slightly convex in specimens smaller than 112.0 mm SL, then sloping to dorsalfin origin; dorsalfin base descending, slightly convex to last ray, dorsal caudal peduncle forming a moderately concave curve to caudalfin base. Ventral head profile straight, slightly descending to pelvicfin insertion; chest slightly convex in one specimen 192.0 mm SL; straight, horizontal from pelvicfin insertion to origin of anal fin; analfin base straight, ascending; ventral caudal peduncle straight to slightly concave, slightly ascending or horizontal in specimens 45.0 mm SL and smaller; ventral caudal peduncle 1.5–1.6 times in dorsal. Lips moderately wide, lower without caudally expanded fold (see Kullander et al., 1992, Fig. 3 View Figure ). Maxilla reaching at most one third of the distance between nostril and orbit; ascending premaxillary process reaching slightly above midline of orbit. Opercule, preopercule, cleithrum, postcleithrum, and posttemporal lacking serration.
Scales. E 1 33 (4), 34 (10), 35 (3); scales between upper lateral line and dorsal fin 5.5– 7.5 anteriorly, 2.5 posteriorly. Scales between lateral lines 2. Scales on upper lateral line 21 (1), 22 (4), 23 (9), 24 (1) and lower lateral line 13 (1), 14 (3), 15 (6), 16 (5). Anterior 1 / 3 – 1 / 2 of cheek naked, remainder with ctenoid scales; cheek scale rows 8–9. Opercule and subopercule covered with ctenoid scales. Interopercule with ctenoid scales caudally, otherwise naked. Single postorbital column of cycloid scales. Occipital and flank scales ctenoid. Circumpeduncular scale rows 7 above upper, 9 below lower lateral lines, ctenoid.
Fin scales. Pectoral and pelvic fins naked. Dorsal fin with double or triple columns of ctenoid scales along interradial membranes to one third to one half of fin height. Scaly pad at base of dorsal fin formed by irregularly arranged small, ctenoid scales extending from first spine to fifth to seventh soft ray; specimens 55.5 mm SL or smaller, pad scales are cycloid or moderately ctenoid. Anal fin scaled on anterior section of soft portion, scales ctenoid, arranged in a single column along interradial membranes to one quarter to one third of fin height; anal fin naked in specimens 55.5 mm SL or less. Scaly pad on base of anal fin, scales small, ctenoid. Caudal fin entirely scaled except the tip of rays, and membranes between D 3 and V 3, scales ctenoid. Accessory caudal fin extension of lateral line between V 4 –V 5, absent on dorsal lobe.
Fins. Dorsal XVII 11 (1), XVII 12 (1), XVIII 10 (2), XVIII 11 (6), XVIII 12 (5), XIX 11 (2); anal III 8 (14), III 9 (3). Dorsal spines increasing in length from first to sixth, equal length to ninth, then slightly shorter; lose membranes behind spine tips (lappets) acutely pointed, up to 1 / 3 the length of spines. Soft portion moderately expanded and pointed, reaching about 1 / 3 of caudalfin length, rays 3–6 longest but not produced into filaments; specimens 56.0 mm SL and smaller with rounded soft portion, not quite reaching caudalfin base. Anal fin pointed, with 2 nd and 3 rd soft rays slightly produced, not reaching caudal fin or barely beyond its base in specimens 90.6 and 192.0 mm SL. Caudal fin emarginate with lobes of approximately the same length and without filaments; one specimen 112.1 mm SL with slightly produced rays D 8 and V 8. Pectoral fin elongate, more or less triangular, longest at 4 th ray, reaching 1 st or 2 nd analfin soft rays, then progressively shorter ventrally. Pelvic fin triangular, first ray produced into a filament reaching 5 th analfin soft ray; in one specimen 112.1 mm SL reaching over 1 / 2 of caudalfin length; specimens 45.5 mm SL or less with rays only slightly produced, reaching at most 1 st spine of anal fin.
Teeth. Outer row of upper jaw with 10–28, blunt, slightly recurved unicuspid teeth; much larger than in inner rows, extending along most of premaxillary length. 2–3 inner rows, separated by a clear gap from outer row; teeth very thin, pointed, straight or slightly recurved unicuspids. Inner rows parallel to outer over its length, not forming a tight pad. Outer row of lower jaw with 6–25 unicuspid, blunt, slightly recurved unicuspids; medial 4–5 teeth larger than rest on outer row, cylindrical, slightly recurved, blunt and more labially positioned than rest of row. Inner rows 3–4, only on medial third of dentary, separated from outer row by distinct gap; teeth long, thin, straight or slightly recurved, much smaller than outer row.
Gills. External rakers on first gill arch; 9 (5), 10 (3) on epibranchial lobe, 1 in angle and 12 (7), 13 (2) on ceratobranchial, none on hypobranchial. Microbranchiospines on the outer face of second to fourth arches. Gill filaments with narrow basal skin cover.
Tooth plates. Lower pharyngeal tooth plate elongate; width of bone 80 % of length; dentigerous area 80 % of width; 30 teeth in posterior row, 10 in median row. Anteriormost teeth subconical or subcylindrical, erect; most teeth laterally compressed and with small, low ridge rostrally, cusps on caudal half of teeth; lateral marginal teeth on anterior half like anteriormost, on caudal half smaller and thinner; posteromedial teeth much larger, nearly round in circumference, posterior cusps, almost blunt ( Fig. 5 View Figure ). Ceratobranchial 4 with 4 toothplates with 11, 28, 6 and 4 teeth.
Vertebrae. 14 + 18 = 32 (1), 14 + 19 = 33 (1), 15 + 18 = 33 (3), 15 + 19 = 34 (5), 15 + 20 = 35 (1), 16 + 18 = 34 (4); 11–13 epihemal ribs.
Color pattern in alcohol ( Fig. 3 View Figure ). Base color grayish yellow; nape, snout and upper lip darker gray, fading caudally to base color towards cheek; lower lip yellowish white. No markings on the head, preopercule immaculate. Opercule darker on dorsal third; lower half of opercule and subopercule dusky yellow; silvery white in some specimens, probably depending on preservation. Ventrally, gill cover yellowish white; white in some specimens; branchiostegal membrane grayish. Chest white laterally and ventrally; in best preserved specimens white extends ventrally to base of caudal fin and to scale row H 3 on caudal peduncle ( Fig. 1 View Figure ). Flanks with 6, dorsoventrally directed, yellowishgray bars fading or disappearing ventrally ( Fig. 2 View Figure b). Bar 1 expands from the 4 th or 5 th predorsal scale to the base of the 4 th dorsalfin spine; its anterior edge delimited by the extrascapular and its posterior edge descending vertically and disappearing ventrally at the pectoralfin insertion. Bar 2 extends between the 6 th and 8 th dorsalfin spines, and runs vertically to H 7.
Bar 3 extends between the 10 th and 13 th dorsalfin spines, and runs parallel to bar 2, fading ventrally at H 6 –H 7. Bars 1–3 are generally bisected dorsoventrally by a lighter column about 1 scale wide, giving the appearance of being two narrow bars in some specimens; this feature may be lost on poorly preserved specimens. A diffuse, blackish medial spot coincides with bar 3, extending rostrocaudally between scales 11–12 and 14–15 of E 3 and dorsoventrally between E 3 and E 1, such that the upper lateral line traverses the uppermost row of scales of the spot. Bar 4 extends between the bases of dorsalfin spines 13–14 to 16–18, descends vertically and fades at H 4 –H 5. Bar 5 extends between the first soft ray and ray 4–5 of dorsal fin, it descends vertically and disappears at H 3 –H 4; in other specimens the bar is located between the last dorsalfin spine and ray 3. Bar 6 extends from the base of the 6–7 (4–5 in some specimens) dorsalfin rays and extends to the base of the caudal fin; bar is restricted to dorsal portion of caudal peduncle, above lower lateral line, and is longer horizontally than vertically ( Fig. 2 View Figure b).
Dorsal fin dusky, lappets dark gray or blackish, forming a dark edge along fin; soft and posterior third of spinous portion whitespotted on interradial membranes; four distinguishable longitudinal, parallel, grayish stripes alternate with light stripes along most of fin, turning almost hyaline rostrally; number of stripes increases with size to 6 in a 192.0 mm SL specimen. Anal fin hyaline to slightly dusky; 4 longitudinal, parallel gray stripes along soft portion of fin (5 in largest specimen). Caudal fin dusky, with round, whitish spots increasing in size towards dorsal edge; spots develop into horizontal stripes in larger specimens and a 192.0 mm SL specimen shows virtually no spots; specimens 55.5 mm SL and smaller with 4 dark, vertical bars. Pectoral fin immaculate. Pelvic fin whitish gray, dusky distally; dusky in largest specimen (192.0 mm SL), spine and first ray whitish gray to dusky.
Live colors ( Fig. 4 View Figure ). Background color greenish gray, breeding specimens more metallic gray. Head without markings except for iridescent blue on the upper lip, continued as a stripe extending to the corner of the preopercule, and a slight marking of the same color on the ventral edge of orbit. A variable number of iridescent blue spots on the preopercule apparently limited to breeding specimens. Six yellow stripes extend between the base of dorsal and H 4–5; in adult, breeding specimens, dorsalmost stripes appear as brownishorange vermiculations and spots. Ventrum distinctly white; breeding adults with bright orange or red chest. Dorsal and anal fins reddish with faint iridescent blue horizontal banding that turns brighter during breeding; caudal brownish red with iridescent blue spots and bands in no clear pattern; pelvic reddish orange with iridescent blue banding, first ray white or very light blue. An aquarium photograph in Weidner (2000: 148, Fig. 1 View Figure ) of an unidentified Geophagus from Venezuela is undoubtedly of a mature adult of G. abalios .
Distribution and habitat. ( Fig. 9 View Figure ) Geophagus abalios is commonly found in black or clear water rivers in the llanos, and is known from the Apure, CinarucoCapanaparo, and AguaroGuariquito drainages. Its current northernmost collection locality is “Las Majaguas” dam in the Río Cojedes, where it was probably introduced by recommendation of the Venezuelan ichthyologist A. FernándezYépez. According to his account (FernándezYépez and Anton, 1966), Geophagus species were not naturally present in the reservoir, and he recommended the introduction of " Geophagus surinamensis " along with some other species, presumably for sport fishing purposes. G. abalios reaches the Andean piedmont to the west, and is the only Geophagus found in clear to white water seasonal lagoons along the mainstem of the Orinoco to the east ( Rodríguez and Lewis Jr. 1990; 1994). The species appears restricted to the Caura drainage on the Guyana Shield, but it extends into the tributaries of the middle and upper Orinoco, including the Ventuari, Mavaca, and along the Río Casiquiare, nearly to the headwaters of the Río Negro.
Etymology. From the Greek a, not or without and balios, spotted. In reference to the lack of preopercular markings. To be regarded as an adjective in masculine form.
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