Steindachnerina pupula Vari 1991

Dorsal soft rays (total): 11 - 12; Analsoft rays: 9 - 10; Vertebrae: 33 - 34

Steindachnerina pupula

DIAGNOSIS.—The lobulate fleshy processes on the roof of the oral cavity, absence of a wide, flattened prepelvic region of the body, lack of a dark midlateral stripe on the body, presence of a dark spot on the basal portions of the middle rays of the dorsal fin, and the possession of 42 to 46 lateral-line scales to the hypural joint and 7½ to 9 scales above the lateral line to the origin of the dorsal fin, in combination, discriminate Steindachnerina pupula from its congeners.

DESCRIPTION.—Body moderately elongate, somewhat compressed, less so in ripe females. Dorsal profile of head convex anteriorly, straight or very slightly convex from vertical line through anterior nostril to rear of head. Dorsal profile of body smoothly curved from rear of head to origin of dorsal fin; straight or slightly convex and posteroventrally slanted at base of dorsal fin, straight or gently convex from base of last dorsal-fin ray to caudal peduncle. Dorsal surface of body with obtuse median keel immediately anterior to dorsal fin, smoothly rounded transversely posterior to fin. Ventral profile of body gently curved from tip of lower jaw to caudal peduncle; curvature less pronounced in smaller specimens. Prepelvic region obtusely flattened, with scales irregularly arranged. Postpelvic region transversely rounded.

Greatest depth of body 0.29–0.36 [0.33]; snout tip to origin of dorsal fin 0.46–0.51 [0.48]; snout tip to origin of anal fin 0.82–0.86 [0.83]; snout tip to insertion of pelvic fin 0.51–0.55 [0.52]; snout tip to anus 0.75–0.80 [0.75]; origin of dorsal fin to hypural joint 0.55–0.59 [0.57]. Dorsal-fin margin straight or slightly convex; anteriormost rays approximately three times length of ultimate ray. Pectoral fin obtusely pointed; length of pectoral fin 0.16–0.22 [0.19], extends about three-quarters distance to vertical through insertion of pelvic fin. Pelvic fin pointed, length of pelvic fin 0.19–0.24 [0.21], reaches about two-thirds distance to origin of anal fin. Caudal fin forked. Adipose fin well developed. Anal fin distinctly emarginate, anteriormost branched rays about two and one-half times length of ultimate ray. Caudal peduncle depth 0.11–0.13 [0.12].

Head obtusely pointed in profile, head length 0.28–0.31 [0.29]; mouth distinctly inferior; portion of buccopharyngeal complex on roof of oral cavity in adults consisting of multiple lobulate fleshy bodies; snout length 0.29–0.34 [0.31]; nostrils very close, anterior circular, posterior crescent-shaped, with aperture partially closed by thin flap of skin separating nares; orbital diameter 0.29–0.34 [0.31]; adipose eyelid present, particularly well developed anteriorly, with broad, vertically ovoid opening over center of eye; length of postorbital portion of head 0.38–0.43 [0.38]; gape width 0.28–0.34 [0.32]; interorbital width 0.38–0.44 [0.41].

Pored lateral-line scales to hypural joint 42 to 46 [44]; all scales of lateral line pored, canals in scales straight; 4 to 6 series of scales extend beyond hypural joint onto caudal-fin base; 7½ to 9 [8½] scales in transverse series from origin of dorsal fin to lateral line; 6 or 6½ [6½] scales in transverse series from lateral line to origin of anal fin.

Dorsal-fin rays ii,9 or iii,9 (when three unbranched rays present, first very short) [iii,9]; anal-fin rays ii,7 or iii,7 (when three unbranched rays present, first very short) [ii,7]; pectoral-fin rays 14 to 16 [14]; pelvic-fin rays i,8 [i,8].

Total vertebrae 33 (8), 34 (33).

COLOR IN ALCOHOL.—Overall coloration of specimens retaining guanine on scales, silvery, darker on dorsal portions of head and body. Overall coloration of specimens lacking guanine on scales tan to tan-brown, darker on dorsal portions of head and body. Scales situated dorsal of lateral line with diffuse patches of small, dark chromatophores, pigmentation more dense proximate to dorsal midline. Specimens collected in Whitewaters with dark pigmentation on body and dorsal fin less pronounced. Deep-lying band of dusky pigmentation extends from rear of supracleithrum to rear of caudal peduncle. Some specimens with diffuse horizontally elongate patch of faint, dark pigmentation on midlateral surface of caudal peduncle (Figures 54, 55).

Dorsal fin typically with discrete patch of dark pigmentation on basal portion of middle rays of dorsal fin (Figures 54, 55), spot most frequently quite dark, but sometimes faint as in specimens known to be collected in Whitewaters (Figure 56). Dorsal fin dusky anteriorly and distally. Lower lobe of caudal fin dusky, remainder of fin with scattered dark chromatophores. Anal and paired fins hyaline.

DISTRIBUTION.—Río Orinoco basin in both Venezuela and Colombia (Figure 57).

ETYMOLOGY.—The specific name, pupula, from the Latin for pupil of the eye, refers to the dark, pupil-like spot at the base of the dorsal fin that is characteristic for the species.

COMPARISONS.—Steindachnerina pupula is most similar to and most likely to be confused with S. dobula, a species occurring along the Amazonian Andean piedmont in Colombia, Peru, and Bolivia. Steindachnerina pupula is distinguished from S. dobula by the presence of 7½ to 9, most frequently 8 or 8½ scales in transverse series from origin of dorsal fin to lateral line, contrary to 6½ to 7½ scales in that series in S. dobula; by the presence of a very dark spot on the basal portions of the middle dorsal-fin rays, contrary to the lack of any pigmentation or rarely some very faint dorsal-fin pigmentation in S. dobula; and by the lack of pigmentation on the midlateral surface of the caudal peduncle in S. pupula, contrary to the faint to intense pigmentation in that region in S. dobula.

Three other species of Steindachnerina occur within the known range of S. pupula. Two of these, S. bimaculata and S. argentea, lack the lobulate fleshy processes on the roof the oral cavity found in S. pupula. Steindachnerina pupula is readily distinguished from the third congener in the basin, S. guentheri, by overall body form, pigmentation, and various meristic features.

TYPE MATERIAL.—17 specimens (17, 48.3–99.3).

HOLOTYPE.—VENEZUELA. Guarico: Small caño on north shore of Río Orinoco, draining into Río Orinoco approximately 1 km upstream of mouth of Río Zuata, MBUCV V-19300, 1 (77.1).

PARATYPES.—Venezuela. Guarico: collected with holotype, USNM 302170, 1 (60.7). Laguna Los Guácimos, Fundo Pecuario Masaguaral (~ 08°34′N, 67°35′W), R.P. Vari et al., 19 Jan 1983, USNM 258008, 2 (97.8–99.3). Fundo Pecuario Masaguaral, Río Coracol, where crossed by bridge (~ 08°34′N, 67°30′W), R.P. Vari et al., 19 Jan 1983, USNM 258081, 3 (52.2–56.0). Caño near “El Estacion Campo El Salado, Universidad Simon Rodriquez,” approximately 65 km S of Santa Maria de Ipire, F. Mago-Leccia et al., MBUCV V-19301, 4 (85.3–97.7). Río Portuguesa, near confluence with Río Apure, H. Mendoza et al., 9 May 1975, MBUCV V-8942, 1 (63.7). Portuguesa: Lagoon on right bank of Río Portuguesa, above Nueva Florida (~ 08°57′N, 69°01′W), L. Aguana, et al., MBUCV V-19302, 1 (79.7). Bolivar: La Paragua (06°50′N, 63°20′W), F. Mago-Leccia, 5–8 Oct 1966, MBUCV V-13489, 2 (50.7–54.4). Territorio Federal Delta Amacuro: Lagoon on north side of Río Orinoco, opposite Isla Tres Caños, west of Caño Araguaito (08°40′30″N, 61°58′30″W), E. Marsh et al., 13 Nov 1979, USNM 235462, 2 (48.3–53.5).

The following 65 nontype specimens were also examined.

VENEZUELA. Apure: Caño Los Zorros and beaches, near Boquerones. MBUCV V-633, 1 (63.0). Río Apure, in front of its junction with Río Portuguesa, San Fernando de Apure, MBUCV V-9343, 1 (66.2). Mouth of Río Apurito, San Fernando de Apure, MBUCV V-9063, 6 (65.9–99.8). Río Apure, west of San Fernando de Apure, USNM 258218, 1 (62.4). Río Cunaviche, at Cunaviche (~ 07°24′N, 67°27′W), USNM 257556, 3. Codegas: Río Tinaco, below bridge on road from Tinaco to Pao, Río Portuguesa system, MAC 68530, 3 (now deposited at MBUCV). Bolivar: Lagoon on south side of Isla Isabella, USNM 235449, 2 (50.9–51.2). Mouth of Río Paraguazu, Río Cuchivero-Chivapuri system, MBUCV V-60104, 2 (72.0–73.4, formerly MAC 69104). Barinas: Río Las Palmas, USNM 194177, 3 (1, 68.1); MBUCV V-19304, 1. Río Michay, Río Suripa system, MAC 68095, 1 (now deposited at MBUCV). Guarico: Río Tizando, at bridge along highway from Tinaco to Don Caminto, MBUCV V-7105, 1 (100.1). Río Tinaco, below bridge along road from Tinaco to Pao, MBUCV V-19035, 3.

COLOMBIA. Meta: Río Meta system, ox-bow lake connected with Río Negro, approximately 500 m S of La Balsa, NRM SIL/1988021.3187, 2. Río Meta system, Río Negro where crossed by road from Villavicencio to Puerto Lopez at La Balsa, NRM SIL/1988021.3131, 3; NRM SIL/1988026.3132, 32.