Ectrepopterus uruguayensis Fowler 1943

Malabarba, Luiz R., Bertaco, Vinicius A., Carvalho, Fernando R. & Litz, Thomas O., 2012, Revalidation of the genus Ectrepopterus Fowler (Teleostei: Characiformes), with the redescription of its type species, E. uruguayensis, Zootaxa 3204, pp. 47-60 : 50-56

Ectrepopterus uruguayensis Fowler 1943

( Figs. 1–6 ; Table 2 )

Megalamphodus uruguayensis Fowler 1943:313 (type locality: Uruguay, no further locality data available; type species of the subgenus Ectrepopterus by original designation and monotypy; mistyped also as Magalamphodus uruguayensis ).

Megalamphodus (Ectrepopterus) uruguayensis . Géry 1972:14 (redescription of holotype).

Megalamphodus uruguayensis . Géry 1977:586 (in key).

Hyphessobrycon uruguayensis . Weitzman and Palmer 1997:234 (listed as a valid species probably belonging to the rosy tetra group). Thomaz et al. 2010 (phylogeny based on DNA sequences).

Diagnosis. The same for the genus. The larger number of maxillary teeth (6–11) and the presence of longitudinal, wavy stripes laterally on body in larger specimens further distinguish this species from several characids.

Description. Morphometric data are summarized in Table 2 . Body compressed and elongate; greatest body depth near to dorsal-fin origin. Dorsal head profile nearly straight. Dorsal body profile convex from supraoccipital bone to base of last dorsal-fin ray and straight from this point to adipose-fin origin. Ventral profile of head smoothly convex. Ventral body profile slightly convex to nearly straight from pectoral-fin origin to pelvic-fin origin, and straight to anal-fin origin. Body profile along anal-fin base posterodorsally slanted. Caudal peduncle elongate, nearly straight to slightly concave along dorsal and ventral margins.

tion. The range not includes the holotype.

Mouth terminal, lower jaw projecting slightly more than upper jaw. Maxilla long and slightly curved aligned at angle of approximately 45 degrees relative to longitudinal body axis. Maxilla slightly widened anteroposteriorly, and extends to junction of infraorbital 2 and 3.

Premaxilla with one or two tooth rows: outer row, when present, with one to two tricuspid teeth; inner row with six to seven tricuspid teeth (7*), gradually decreasing in length from first to fourth or fifth teeth and last two smaller. Maxilla with six to eleven (8*, mode = 10) tricuspidate teeth; and last five or six uni- to tricuspid teeth. Four or five anteriormost dentary teeth larger, tricuspid, followed by one or two medium sized tricuspid teeth, and eight to 13 teeth with one to three cusps. Central cusp in all teeth two to three times longer and broader than other cusps. All cusp tips slightly curved posteriorly towards oral cavity ( Fig. 4 ).

Dorsal-fin rays ii,8–10 (ii,9*; n = 93; ii,8 and ii, 10 in one specimen each); first unbranched ray approximately one-half length of second ray. Dorsal-fin origin located at middle of SL and posterior to vertical through pelvic-fin origin. Distal margin of dorsal fin slightly convex. Adipose-fin located approximately at vertical through insertion of last anal-fin ray. Pectoral-fin rays i,10–12* (mode = 10, n = 93). Pelvic-fin rays i,6 or 7* (mode = 7, n = 93). Pelvic-fin origin located anterior to vertical through dorsal-fin origin. Anal-fin rays iii–v,19–26 (22*, rarely 19 or 24–26, mode = 22, n = 93). First unbranched ray normally only apparent in cleared and stained specimens. Anal-fin origin posterior to vertical through base of last two dorsal-fin ray. Caudal-fin forked, lobes similar in size, with 18– 20 principal rays (19*, two with 18 and one with 20, n = 92). Dorsal procurrent rays 9–11 (mode = 10, n = 10), and ventral procurrent rays 8–10 (mode = 9, n = 10).

Scales cycloid, moderately large. Lateral line incomplete, perforated scales 5–9 (8*, one specimen with 5 and one specimen with 9, mode = 6, n = 93). Longitudinal scale series including pored scales 32*–36 (mode = 33, n = 93). Scale rows between dorsal-fin origin and lateral line 6 or 7* (mode = 6, n = 93); scale rows between lateral line and pelvic-fin origin 4–6 (5*, mode = 5, n = 93). Predorsal scales 10*–13, arranged in regular series (mode = 11, n = 82). Scale rows around caudal peduncle 14* (n = 93). Scale sheath along anal-fin base 6–12 (8*, mode = 8) scales in single series, extending to base of fifth to tenth branched rays.

Precaudal vertebrae 16* or 17 (mode = 16, n = 11); caudal vertebrae 16 or 17* (mode = 17, n = 11); total vertebrae 33* or 34 (mode = 33, n = 11). Supraneurals 5 or 6 (mode = 6, n = 10). Gill rakers on upper limb of outer gill arch 5 or 6 (mode = 6), and on lower limb 9–11 (mode = 9, n = 10). Ventral extent of third infraorbital reaching horizontal arm of preopercle, but not reaching the laterosensory canal of preopercle. Fontanels forming slightly narrow groove; parietal little longer than frontal. Frontals not contacting anteriorly to frontal fontanel.

Color in alcohol. The holotype is discolored, except for the humeral spot ( Fig. 1 ). Color description based on non-type specimens ( Fig. 5 ). Dorsal and dorsolateral portion of head and body pigmented dark brown. Scales on lateral and dorsal surface of body with scattered dark brown chromatophores. In some specimens larger than 35.0 mm SL the dorsal and ventral border of scales are dark brown pigmented forming a wavy, striped pattern between longitudinal rows of scales, more conspicuous in middle portion of body ( Fig. 5 ). One narrow humeral spot vertically elongate, located over third to fourth lateral line scales and extending over two longitudinal series of scales above and below of lateral line. Midlateral body stripe very narrow extending from posterior middle region of body to base of median caudal-fin rays, wide and more densely pigmented on caudal peduncle forming a triangle spot. Anteriorly directed chevron-shaped marks along the midlateral body. Small black chromatophores scattered over rays of all fins. Caudal-fin rays darkened black in the distal portion. Adipose-fin smoothly dark black pigmented along the distal border.

Color in life. Color pattern similar to described for alcohol preserved specimens. Overall body and head color pattern silvery to golden ( Figs. 5 and 6 ). Chromatophores distribution pattern of head, body and fins as described above for alcohol preserved specimens. Eye with upper third of iris iridescent red. Dorsal fin yellowish. Pectoral fin hyaline. Pelvic fin orangish. Anal fin yellowish, more intense along proximal half of most anterior anal-fin rays. Adipose fin yellowish. Caudal fin yellowish, mostly at the proximal half of the dorsal and ventral caudal-fin lobes; middle caudal-fin rays and distal third portion or distal half of caudal-fin rays with dark black melanophores ( Figs. 5 and 6 ). Wavy, striped pigmentation pattern along the scales is not clearly discernible in living specimens.

Sexual dimorphism. Mature males of Ectrepopterus uruguayensis are recognized by the presence of small bony hooks on all rayed fins (absent in females). Mature males present bony hooks in the third distal portion of the first to fifth branched rays, and in the distal portion of all pectoral-fin rays. Pelvic fin usually bearing bony hooks along ventromedial border of the unbranched and first to fourth branched rays. Anal-fin rays bearing one small, elongate, retrorse bony hook along posterolateral border of each segment of lepidotrichia, usually along last unbranched ray to last branched ray, in the distal portion of all caudal-fin rays, and in the two posteriormost procurrent caudal-fin-rays. Hooks usually located along of distal portion of each ray. Anal-fin profile nearly straight in males and smoothly concave in females. The presence of bony hooks is often found in males, but only mature males (specimens larger than 33.0 mm SL) possess bony hooks on all rayed fins. Pectoral-fin tip reaching pelvic-fin origin in males but not in females. Pelvic-fin tip surpass anal-fin origin in males but not in females. Males and females also differ by anal-fin profile, which is nearly straight in males and smoothly concave in females. Gill glands were not found on first gill arch on both mature males and females.

Distribution. Ectrepopterus uruguayensis occurs in the lower tributaries of the río Uruguay (río Cuareim, río Salto, and río Negro basins), and río de La Plata (río Santa Lucía and arroyo Pand), in Uruguay ( Fig. 7 ). The Uruguay River basin in Brazil has been extensively sampled for the last 20 years, with intensive collecting undertaken in some localities, and so far there are no records of the species in this country. Menni (2004) listed Hyphessobrycon uruguayensis (= E. uruguayensis ) for Argentina without any specific location or list of examined material.

Ecological notes. Ectrepopterus uruguayensis inhabits streams, and occurs in semi-lentic and lotic shallow areas (up to 1.2 m deep) with moderate submerged vegetation and riparian vegetation composed by trees and shrubs or absent. The streams have transparent water, and bottom with mud, some stretches with sand or gravel. Water temperature measured during field work ranged from 10 to 30°C, depending on the season. The pH was found around 7 in the neutral range. Keeping these conditions under consideration, Ectrepopterus uruguayensis can be easily kept in aquaria up to eight years. This species is usually collected in small numbers in natural habitats. Observations in aquaria (TOL) showed that, contrary to many other characids, it does not form schools, but rather specimens stay mainly alone, without showing territorial behavior.

Material examined. All from Uruguay: ANSP 70331, holotype, female, 29.2 mm SL, 1935, F. Felippone. MCP 13080, 5 (1 c&s), 27.7–36.5 mm SL, arroyo Catalán, puente de la ruta 30, Artigas, ca. 30º50’S 56º14’W, 9 Jul 1987, L. H. Amato. MCP 31907, 3 (1 c&s), 33.3–39.7 mm SL, arroyo Salsipuedes, tributary of the río Tacuarembó, Tacuarembó, 32º20’39’’S 56º15’13’’W, 15 Aug 2002, P. Laurino et al. MCP 31915, 35.9 mm SL, arroyo Catalán Grande, Artigas, 30º50’40’’S 56º14’30’’W, 16 Aug 2002, P. Laurino et al. MCP 33504, 2, 30.2– 35.9 mm SL, arroyo Saucedo, Salto, 31º06’28’’S 57º30’25’’W, 17 Mar 2003, P. Laurino et al. MCP 33505, 6 (2 c&s), 23.6–29.1 mm SL arroyo Palomas (loc 2), Salto, 31º04’43’’S 57º37’26’’W, 17 Mar 2003, P. Laurino et al. MCP 33506, 4, 27.1–28.7 mm SL, arroyo Palomas (loc 1), Salto, ca. 31º03’16’’S 57º37’43’’W, 17 Mar 2003, P. Laurino et al. MCP 33507, 4, 25.5–33.3 mm SL, arroyo Cardoso, San José, 34º24’50’’S 56º26’49’’W, 23 Mar 2003, E. Lartigau et al. MCP 36790, 33.8 mm SL, arroyo Pando, Canelones, 34º44’19”S 54º56’27”W, 26 Aug 2004, P. Laurino et al. MCP 36791, 2, 38.7–42.1 mm SL, creek near Paso de San Borja, Durazno, 33º24’57”S 56º25’57”W, 22 Aug 2004, P. Laurino et al. MCP 36792, 35.6 mm SL, arroyo Pando, Canelones, 34º42’12”S 55º56’43”W, 31 Aug 2004, T. O. Litz et al. MCP 36795, 13, 29.2–43.4 mm SL, ditch between arroyo Salsipuedes and ruta 5 Km 289.5, tributary of the rio Tacuarembó, Tacuarembó, 32º29’13”S 56º22’44”W, 22 Aug 2004, P. Laurino et al. MCP 36796, 8, 28.8–35.8 mm SL, arroyo Catalán Grande, Artigas, 30º50’40”S 56º14’30”W, 23 Aug 2004, P. Laurino et al.; MTD-F 27461–27466, 6, 25.9–35.6 mm SL, arroyo Palomas (loc 2), Salto, 31º04’43’’S 57º37’26’’W, 17 Mar 2003, P. Laurino et al. UFRGS 7169, 4, 29.0–32.0 mm SL, arroyo Mestre de Campo, on road to Polanco of YI, drainage of río YI, Durazno, 33º24’55’’S 56º12’06’’W, 29 May 2005, L. R. Malabarba et al. UFRGS 7170, 11, 30.2–40.0 mm SL, arroyo affluent to arroyo Mestre de Campo, on road to Polanco of YI, drainage of río YI, Durazno, 33º23’S 56º13’W, 29 May 2005, L. R. Malabarba et al. UFRGS 7171, 23, 36.2–44.5 mm SL, arroyo on road 26 ca. 59 km of Melo, between arroyos Saule and Fratile Muerto, Melo, 32º17’39’’S 54º44’59’’W, 28 May 2005, L. R. Malabarba et al. UFRGS 7172, 2, 36.4–39.6 mm SL, marginal pool and arroyo Corrales, on road 27, drainage of río Tacuarembó, Rivera, 31º23’26’’S 55º15’14’’W, 27 May 2005, L. R. Malabarba et al. UFRGS 7343, 1, 36.7 mm SL, río Caraguatá,

río Tacuarembó basin, Tacuarembó, 32º09’29”S 55º01’27”W, 28 May 2005, L. R. Malabarba et al. UFRGS 7474, 30.6 mm SL, arroyo Cuñapiru, río Tacuarembó basin, km 12.3 road 27, Rivera, Rivera, 3102’21”S 5529’31”W, 27 May 2005, L. R. Malabarba et al. UFRGS 7506, 47.9 mm SL; UFRGS 10564, 2 ethyl alcohol anhydrous, 38.2– 40.0 mm SL, arroyo on road 26 about 59 km of Melo, Cerro Largo, 32º17’39”S 54º44’59”W, 28 May 2005, L. R. Malabarba et al. UFRGS 7767, 3, 37.2–40.5 mm SL, arroyo Cuaró Grande on road 4, tributary of río Quaraí, Artigas, Artigas, 30º47’03”S 56º46’54”W, 8 Sep 2005, L. R. Malabarba et al. UFRGS 7785, 1, 37.1 mm SL; UFRGS 12345, 1 ethyl alcohol anhydrous, 38.2 mm SL, arroyo Carpinchuri, tributary of río Uruguay on road 3, Paysandu, Paysandu, 31º40’38”S 57º53’30”W, 20 Sep 2005, L. R. Malabarba et al. UFRGS 7899, 1, 39.7 mm SL, arroyo Chapicuy Chico , tributary of río Uruguay on road 3, Paysandu, Paysandu, 31º37’20”S 57º52’51”W, 10 Sep 2005, L. R. Malabarba et al. UFRGS 7909, 9, 33.1–40.2 mm SL, cañada Cecilia on road 3, km 512, Salto, Salto, 31º16’01”S 57º46’42”W, 9 Sep 2005, L. R. Malabarba et al. UFRGS 7918, 2, 38.9–44.4 mm SL, cañada on road 4, tributary of río Queguay Grande, Paysandu, Paysandu, 32º12’25”S 57º12’47”W, 10 Sep 2005, L. R. Malabarba et al. UFRGS 7945, 36.9 mm SL, cañada on road 4, tributary of río Queguay Chico , Paysandu, Paysandu, 32º01’57”S 57º19’30”W, 10 Sep 2005, L. R. Malabarba et al. UFRGS 7985, 53, 29.8–44.3 mm SL, arroyo Guaviyú on road 3, tributary of río Uruguay, Artigas, Artigas, 30º37’51”S 57º41’18”W, 9 Sep 2005, L. R. Malabarba et al. UFRGS 8009, 40.2 mm SL, arroyo los Chanchos on road 3, río Daymán basin, Paysandu, Paysandu, 31º28’34”S 57º54’06”W, 10 Sep 2005, L. R. Malabarba et al. UFRGS 8073, 9, 33.5–42.9 mm SL, arroyo de las Tunas on road 31, tributary of río Arapey Grande, Salto, Salto, 31º20’04”S 57º19’36”W, 8 Sep 2005, L. R. Malabarba et al. UFRGS 8105, 2, 42.3–46.4 mm SL, arroyo on road 4, tributary of río Valentin Grande, Salto, Salto, 31º16’32”S 57º09’22”W, 8 Sep 2005, L. R. Malabarba et al. UFRGS 8578, 27 (4 c&s), 39.3–40.8 mm SL, arroyo Tala on road 31 between Salto city and Artigas, 31º23’09’’S 57º33’46’’W, L. R. Malabarba et al. UFRGS 10973, ethyl alcohol anhydrous, 32.8 mm SL, arroyo Tala on road 31, tributary of río Uruguay, Salto, Salto, 31º23’09”S 57º33’46”W, 8 Sep 2005, L. R. Malabarba et al. UFRGS 11129, 2 ethyl alcohol anhydrous, 33.3–38.9 mm SL, arroyo Corrales and lateral puddles on road 27, río Tacuarembó basin, Rivera, Rivera, 31º23’26”S 55º15’14”W, 27 May 2005, L. R. Malabarba et al. ZVC-P 423, 8, 28.8–38.8 mm SL, arroyo Bolón, tributary of the arroyo Tomás Cuadra, río Negro drainage, ca. 33º12’S 56º10’W, E. Messner. ZVC-P 1464, 16 (2 c&s), 31.3–47.4 mm SL, arroyo Higuera, tributary of the arroyo Carpinteria, río Negro drainage, Tacuarembó, ca. 31º45’S 55º13’W, 5 Oct 1959, E. Messner. ZVC-P 1769, 31.8 mm SL, río Santa Lucía, Arequita, Levalleja, ca. 34º20’S 55º15’W, Carbonell. ZVC-P 2975, 4, 25.6– 27.5 mm SL, Estancia San Francisco, 5 km W from Casupá, Florida, ca. 34º05’S 55º40’W, 12 Apr 1981, E. Lessa & D. Lisandro. ZVC-P 5267, 53, 16.1–24.3 mm SL, arroyo Mahoma Chico , tributary of the río San José, San José, ca. 34º02’S 56º58’W, 4 Jan 1953.

Figures

FIGURE 1. Ectrepopterus uruguayensis, ANSP 70331, holotype, female, 29.2 mm SL, Uruguay. Photo by K. Luckenbill.

FIGURE 2. Ectrepopterus uruguayensis, UFRGS 8578, 37.4 mm SL, male. Lower and upper jaws showing the premaxilla (PMX), maxilla (MAX) and dentary (DEN), and suspensorium showing the foramen in posterior region of metapterygoid (MTP) forming an incomplete arch and bordered posteriorly by the hyomandibula (HYO), left side. Scale bar = 1 mm.

FIGURE 3. Ectrepopterus uruguayensis, UFRGS 8578, 37.4 mm SL, male. Infraorbital series (IO 1 – 6) and antorbital (AOR), left side. Scale bar = 1 mm.

FIGURE 4. Ectrepopterus uruguayensis, MCP 31907, 38.5 mm SL, male. Scanning electronic micrograph of lower and upper jaws, right side. Scale bars = 0.5 mm.

FIGURE 5. Ectrepopterus uruguayensis, UFRGS 8073, 42.9 mm SL, arroyo de las Tunas on road 31, tributary of río Arapey Grande, Salto, Salto, Uruguay. The same specimen photographed alive (above) and six years after fixation in formalin and preservation in ethanol 70 %.

FIGURE 6. Ectrepopterus uruguayensis, aquarium live specimen, not preserved.

FIGURE 7. Drainages of laguna dos Patos system (right upper) in Rio Grande do Sul State, Brazil and left part of río Uruguay basin in Uruguay and Brazil, showing the distribution of Ectrepopterus uruguayensis. Some symbols represents more than one lot and locality.

Tables

TABLE 2. Morphometric data of holotype (H) and non-types specimens of Ectrepopterus uruguayensis. SD = Standard devia-

Character Standard length (mm) Percents of Standard Length Predorsal distance	H 29.2 56.6	n 86 86	Range 23.4–47.4 57.0–61.3	Mean 32.1 59.3	SD – 0.9
Prepelvic distance Prepectoral distance Preanal distance Depth at dorsal-fin origin Caudal peduncle depth Caudal peduncle length	50.7 30.6 65.7 41.4 12.8 10.6	86 86 86 86 85 86	49.1–55.9 27.7–34.1 62.7–72.7 37.5–48.5 11.6–14.6 7.4–10.6	52.4 31.9 67.7 42.4 12.9 8.9	1.2 1.5 1.4 2.3 0.6 2.5
Anal-fin base Dorsal-fin length Pelvic-fin length Pectoral-fin length	32.8 33.5 18.8 21.6	86 83 86 86	29.9–35.1 29.3–35.7 16.0–21.3 17.3–24.3	32.4 31.9 18.5 21.1	1.2 2.1 1.0 1.1
Head length Percents of Head Length	30.8	86	27.5–32.8	30.4	1.2
Snout Length Upper jaw length Orbital diameter Interorbital width	21.3 56.1 38.3 30.4	86 86 86 86	19.7–27.4 50.2–57.3 33.2–41.3 28.1–34.9	23.8 53.2 38.1 31.7	1.3 1.3 1.6 1.6