Diapoma terofali ( Géry, 1964 )

Menezes, Naércio A. & Weitzman, Stanley H., 2011, A Systematic Review Of Diapoma (Teleostei: Characiformes: Characidae: Stevardiinae: Diapomini) With Descriptions Of Two New Species From Southern Brazil, Papéis Avulsos de Zoologia 51 (5), pp. 59-82 : 62-67

Diapoma terofali ( Géry, 1964)

Figs. 10-15 , Table 1

Glandulocauda terofali Géry, 1964:2 (original description, type locality: Argentina, Provincia Buenos Aires, Canal El Cazador, río Luján). Ringuelet, Aramburu & Aramburu, 1967:156 [description after Géry (1964)]. – Géry, 1977:355, 362 (illustrated and listed). – Miquelarena, Aramburu, Menni & López, 1981:131 (specimens from Argentina, provincia de Corrientes, laguna Iberá and Berisso, provincia de Buenos Aires; meristic and morphometric data). – Miquelarena, 1982:281, 292 (caudal osteology). – Malabarba, 1983:187 (listed; specimens from rio Negro, Bagé and rio Santa Maria, Dom Pedrito, Rio Grande do Sul, Brazil). – López, Casciotta, Miquelarena & Menni, 1984:76, 78 (short descriptions, no new localities). – Miquelarena, 1986:22 (dentition). – Menni, 2004:76 (ecological data).

Diapoma terofali Weitzman & Fink, 1985:103 , 109 (discussion of generic placement, specimens from laguna of arroyo Catalán Chico, Artigas, Uruguay). – Burns et al., 1995:140 (shape of sperm cells). – Weitzman, 2003:224 (maximum length; distribution; remarks and references). – López et al., 2003:21 (listed; distribution, conservation). – Casciotta et al., 2003:83 (laguna Iberiá, Argentina). – Menezes, 2007:38 (listed in catalog; distribution). – Javonillo et al., 2010:500 (listed in table); 2010:509 (listed as member of Stevardiinae ).

Specimens examined: Argentina: ANSP 139721 , 1 (SL 47.5 mm), Buenos Aires, canal “El Cazador”, río Luján , approximately 34°17’S, 58°53’W, paratype ; UMMZ 218481 , 120 (SL 37-55.5 mm), Los Talas, 20 km SE of La Plata , approximately 34°52’S, 57°53’W . Brazil: MZUSP 28268 (SL 42 mm, male and 38 mm, female, C&S, SL 42 mm, male and 38 mm, female, photographed) , USNM 270284 (SL 29.1-46.5 mm), Rio Grande do Sul, rio Santa Maria under bridge on road BR 293 , between Dom Pedrito and Santana do Livramento , approximately 30°57’S, 55°05’W ; UFRGS 18821 , 11 (SL 36.8-41 mm), rio Negro , on road between Bagé and Pinheiro Machado, approximately 31°28’S, 53°48’W . Uruguay: USNM 236275 , 2 (37.8 and 39.2 mm), Artigas, laguna of Arroyo Catlán Chico, approximately 30°24’S, 56°28’W ; MCP 1531 , 7 (SL 30-32.8 mm), Cerro Largo, Estância Arreria, rio Negro, approximately 32°12’S, 54°15’W .

Diagnosis: Diapoma terofali can be readily distinguished from D. speculiferum and D. pyrrhopteryx by not having the opercle and subopercle prolonged (compare Figs. 11 and 18 , with Figs. 28 and 35 ). It differs from D. thauma in the number of gill rakers on the

64 MENEZES, N.A. & WEITZMAN, S.H.: REVIEW OF DIAPOMA AND DESCRIPTIONS OF NEW SPECIES FROM SOUTHERN BRAZIL

lower limb of first gill arch (15-18 versus 11-13 in D. thauma , Fig. 3 ) and in the number of anal-fin rays (26-33 versus 24-27, Fig. 1 ).

Description: Morphometrics presented in Table 1.

Body small (SL 32-58.5 mm), compressed, elongate and moderately deep. Greatest body depth located between snout tip and dorsal-fin origin near vertical through pelvic-fin origin. Dorsal body profile convex from snout tip to origin of dorsal fin, slightly depressed at nape, nearly straight along dorsal-fin base and slightly concave above caudal peduncle. Snout rounded. Dorsal-fin origin nearer to caudal-fin base than to snout tip. Ventral body profile more convex than dorsal profile, from tip of lower jaw to anal-fin origin, straight along anal-fin base and slightly concave from end of anal-fin base to origin of procurrent caudal-fin rays. Mouth terminal. Mouth gape inclined posteroventrally towards mandibular joint. Maxilla extending posteriorly beyond vertical passing through anterior border of orbit, but not reaching posterior border of pupil, its posterior ventral border convex, posterior dorsal border concave.

Dorsal-fin rays ii, 8 in all specimens, n = 171. Posteriormost ray unbranched in all specimens, n = 171. Adipose fin present. Unbranched anal-fin rays iv or v, usually iv, branched rays 26-33, 28.8, n = 171. Developed anterior anal-fin lobe includes anterior unbranched rays and first 6-7 branched rays. Anal fin of sexually mature males with bilateral hooks on last unbranched and anterior 10-11 branched rays; hooks distributed as shown in figure 17. Pectoral-fin rays i, 9-12, 10.8, n = 171. Posterior tips of longest pectoral-fin rays reaching and in some specimens extending slightly beyond pelvic-fin origin in males, falling short of pelvic-fin origin in females at all sizes, but pectoral fins about same proportional length in both sexes. Pelvic-fin rays i, 6, n = 171. Sexually mature males with hooks on rays of pelvic fin, distributed as shown in Figure 15 . Number of hooks per ray varying among males, but usually approximately as shown in Figure 15 . Mature male (SL 42 mm) with 8 on fourth, 9 on fifth, and 10 on sixth and 0 on remaining branched and unbranched rays. Tips of longest pelvic-fin rays extending to, or slightly, beyond anal-in origin in adult males and females.

Scales cycloid, with few radii (3-7) along exposed field on body and more numerous (10-12) on enlarged scale bordering pouch opening. Lateral line incomplete, perforated scales on anterior segment 7-14, 9.8, n = 135, followed by 17-30, 24 non-perforated scales, n = 135, and shorter posterior segment with 3-8, 4.7, n = 94 in most specimens. Lateral series scales 35-39, 37.1, n = 133. Scales between dorsal-fin origin and anal-fin origin 10-11, 10.6, n = 160. Predorsal scales 13-16, 14, n = 162. Horizontal scale rows around caudal peduncle 14, n = 141. Premaxillary teeth in two distinct rows ( Fig. 12), larger teeth pentacuspid, smaller teeth barely tricuspid with barely apparent lateral cusps. Outer row teeth 2-5, 3.8, n = 171. Inner row teeth 4-5, 4.06. Maxillary teeth ( Fig. 12) tricuspid anteriorly, bicuspid and smaller posteriorly, 1-6, 3, n = 170. Dentary ( Fig. 12) with 4 large anterior pentacuspid or sometimes quadricuspid teeth, n = 171, and 4-11, 6.7, n = 171 smaller tricuspid teeth. Total number of gill rakers 23-27, 25.1, n = 171. Branchiostegal rays 4 in two cleared and stained specimens, with 3 rays originating from anterior ceratohyal and 1 ray from posterior ceratohyal.

Color in alcohol: Males and females with identical color pattern ( Fig. 10 ). Body pale yellow and slightly darker dorsally than ventrally due to presence of dark chromatophores especially on free edges of scales. Ventral part of body silvery. Dorsal part of head, snout and tip of lower jaw more densely pigmented with dark chromatophores. Faint vertically elongate dark blotch on humeral region. Blotch narrowing ventrally towards short horizontal row of perforated lateral line scales. Anteroventral margin of blotch about four scales distant from posterior edge of upper portion of opercle. Dark lateral body stripe extending from posterior part of dorsal opercular region to caudal-fin base. Stripe mostly obscured by guanine. All fins pale with vestigial dark pigment. Circumorbital bones and opercle silvery with very few scattered dark chromatophores.

Sexual dimorphism, reproductive mode and gonad anatomy: Hooks on the anal and pelvic and fins of males ( Figs. 14 and 15 ) are absent on the same fins of females. Table 1 indicates some statistically significant morphometric differences between males and females (values of p in bold). However, regression analyses that better express differences in sexual dimorphism in body ratios did not provide any significant differences between sexes concerning the same morphological parameters when graphically treated.

Histological analysis ( Burns et al., 1995, Table 3, fig. 3B), indicated the presence of spermatozoa within the ovary and longitudinal sections through the testes revealed that the sperm cells are ovoid.

Distribution: D. terofali is known from streams flowing into rio Uruguay in Uruguay and Rio Grande do Sul, Brazil, and streams flowing into río de La Plata, Buenos Aires, Argentina ( Fig. 16 ).

Figures

FIGURE 1: Tukey box plot showing statistical distribution of number of anal-fin rays for species of Diapoma.

FIGURE 3: Tukey box plots showing statistical distribution of number of lower limb gill rakers for species of Diapoma.

FIGURE 10: Diapoma terofali, MZUSP 28268, adult male above, SL 42.0 mm and adult female below, SL 38.0 mm.

FIGURE 11: Diapoma terofali, MZUSP 28268, C&S, sexually active male, SL 42.0 mm, opercular bones, lateral view, left side. OP, opercle; POP, preopercle; IOP, interopercle; SOP, subopercle.

FIGURE 15: Diapoma terofali, MZUSP 28268, C&S, sexually active male, SL 42.0 mm; pelvic-fin rays, ventral view, left side, showing pelvic-fin hooks.

FIGURE 16: Map of southern South America showing collecting sites and type localities (black symbols) of the species of Diapoma. Squares, Diapoma pyrrhopteryx; triangles, D. speculiferum; diamonds, D. terofali; circles, D. thauma. Some symbols may represent more than one locality.

FIGURE 18: Diapoma thauma, MZUSP 104077, C&S, sexually active male, SL 35.0 mm; opercular bones, lateral view, left side. OP, opercle; POP, preopercle; IOP, interopercle; SOP, subopercle.

FIGURE 28: Diapoma speculiferum, MZUSP 28247, C&S, sexually active male, SL 33.5 mm; opercular bones, lateral view, left side. OP, opercle; POP, preopercle; IOP, interopercle; SOP, subopercle.

FIGURE 35: Diapoma pyrrhopteryx, MZUSP 104323, C&S, sexually active male, SL 52.0 mm; opercular bones, lateral view, left side. OP, opercle; POP, preopercle; IOP, interopercle; SOP, subopercle.