Mimagoniates inequalis (Eigenmann, 1911)

Menezes ¹, Naércio A. & Weitzman ², Stanley H., 2009, Systematics of the Neotropical fish subfamily Glandulocaudinae (Teleostei: Characiformes: Characidae), Neotropical Ichthyology 7 (3), pp. 295-370 : 324-329

Mimagoniates inequalis (Eigenmann, 1911) Figs. 29-30

Glandulocauda inequalis Eigenmann, 1911b: 169 , plate 5, fig. 5, (type locality: “PortoAlegre, Jan. 19, 1909 ”). - Eigenmann, 1914 a: 42 (listed). - Henn, 1928: 68 (listed in type catalog). - Eigenmann & Myers, 1929: 489 (redescription based on type specimens).- Innes, 1935: 122 (aquarium description).- Holly, Meinken & Rachow, 1950: 816 (aquarium description; citation of much aquarium and ichthyological literature previous to 1942). - Fowler, 1951: 413 (listed).- Böhlke, 1958: 43 (listed). - Nelson, 1964a: 62, 68, 120, 127 (systematics; morphology; courtship behavior). - Nelson, 1964b: 129 (courtship behavior). - Nelson, 1964c: 527-533 (courtship behavior). - Géry, 1964: 8 (noted differences between M. inequalis and M. microlepis ). - Géry, 1966: 229 (in key to males of Glandulocauda and Mimagoniates ; unsure of proper generic allocation of G. inequalis ). - Géry, 1977: 362 (listed in a brief discussion of Glandulocauda and Mimagoniates ; unsure of generic allocation of G. inequalis ). - Sterba, 1987: 68 (aquarium description). - Ibarra & Stewart, 1987: 39 (listed in type catalog).

Mimagoniates inequalis Rachow, 1928: 16 (aquarium description). - Schultz, 1959: 11 (key, in part; only specimens from Porto Alegre; listed M. lateralis as a synonym; of specimens listed, M. inequalis USNM 94117 are M. lateralis and USNM 177704 includes 1 spm of M. microlepis ; only USNM 94310 are all M. inequalis ). - Weitzman & Fink, 1985:106, 109 (listed in materials examined with evidence for placement of in Mimagoniates ). - Weitzman et al., 1988: 404-419 (discussion of relationships and biogeography). - Malabarba, 1989: 136 (listed in discussion). - Menezes & Weitzman, 1990: 384 (in key to Glandulocaudini ). - Weitzman & Menezes, 1994: 3 (general discussion in non-systematic literature). - Weitzman et al., 1996: 200, 205, 209 (courtship behavior; reproduction; breeding). - Weitzman, in Reis et al., 2003: 226 (maximum length; distribution; remarks; and references). - Menezes, in Buckup et al., 2007: 39 (listed in catalog; distribution). - Menezes et al., 2008: 38-41 (distribution; discussion of relationships and biogeography).

Diagnosis. Based on the development of the caudal-fin ray pump, M. inequalis seems to be more similar to M. barberi and M. pulcher than to the other species of Mimagoniates but has fewer branched anal-fin rays (26 to 30) and vertebrae (36 to 39) than M. barberi (31 to 36 branched anal-fin rays and 41 to 46 vertebrae). From M. pulcher it differs by the number of lateral series scales (34 to 41 vs. 43 to 46) and horizontal scale rows from dorsal-fin origin to anal-fin origin (15 to 18 vs. 13 to 15).

The most striking color difference between M. inequalis and M. barberi is the presence in M. barberi of a prominent longitudinal black stripe extending from vertical posterior border of eye posteriorly to caudal fin base and in males onto portion of caudal fin occupied by caudal organ. The humeral dark spot is barely distinguishable from horizontal black stripe. In M. inequalis the lateral body shape is diffuse in both sexes and consists of scattered dark chromatophores extending from black vertical humeral spot posteriorly onto caudal fin.

Description. Table 6 presents morphometric data of the holotype and paratypes plus samples from within 70 km of Porto Alegre Rio Grande do Sul, Brazil and from Rivera, Uruguay. Many of the specimens in the description below are immatures to small adults. Therefore the means and other data given for these samples do not accurately reflect population samples with large numbers of adults.

Body compressed, relatively deep, especially near pelvic-fin origin; body deepest at vertical through pelvic-fin origin or just anterior to that position. Predorsal body profile somewhat arched in all specimens which have predorsal profile gently convex to dorsal of eyes. Body profile slightly elevated at dorsal-fin origin. Dorsal body profile nearly straight along dorsal-fin base and then to adipose fin. Body profile posterior to adipose fin somewhat concave dorsal to caudal peduncle. Dorsal-fin origin nearer to caudal-fin base than to snout tip. Ventral profile of body strongly convex in adult males and females from tip of lower jaw to origin of pelvic fin, less strongly convex in immatures.Abdominal profile straight to slightly concave between pelvic-fin base and to anal-fin origin in all specimens. Body profile along anal-fin base in males straight to slightly concave, somewhat concave in females and immatures. Ventral profile of caudal peduncle initially straight but very short in adult males, then slopes downward along strongly developed ventral procurrent caudal-fin rays. Region nearly straight in females and immatures including procurrent ventral caudal-fin rays. Snout blunt. Lower jaw protruding slightly anterior to upper jaw. Lower jaw of adult males somewhat thick and heavy compared to that of females and immatures. Mouth angled posteroventrally. Maxilla long, extending to point horizontal along ventral border of eye in all specimens. Maxilla extending posteriorly to approximately

Males Females and juveniles

Characters

Holotype N Range Mean SD N Range Mean SD dif. Standard length 33.3 66 16.3-38.3 24.2 75 14.5-29.8 19.8

Depth at dorsal-fin origin 33.6 66 27.0-34.0 30.8 1.9 75 26.0-32.8 28.9 1.9 – Snout to dorsal-fin origin 56.2 66 56.1-61.6 59.0 1.4 75 56.0-63.0 59.2 1.5 – Snout to pectoral-fin origin 27.6 66 25.1-30.0 27.2 0.9 75 24.8-30.3 27.4 1.1 – Snout to pelvic-fin origin 46.2 66 42.0-47.0 44.3 1.2 75 42.7-48.8 45.0 1.2 – Snout to anal-fin origin 59.2 66 53.4-59.5 56.6 1.4 75 54.2-60.8 57.1 1.4 – Caudal peduncle depth 15.3 66 10.7-16.6 13.6 1.4 75 09.2-14.7 11.7 1.5 + Caudal peduncle length 09.3 66 08.0-11.2 09.6 0.8 75 07.5-11.7 09.1 0.8 – Pectoral-fin length 23.4 65 20.6-26.0 23.7 1.0 75 20.0-25.7 23.4 1.2 – Pelvic-fin length 17.4 66 12.7-17.5 14.6 1.2 75 10.8-15.5 13.1 0.8 + Dorsal-fin base length 16.5 66 13.0-17.8 15.0 1.1 75 12.3-17.6 14.6 1.1 – Dorsal-fin height 28.8 64 20.1-28.8 24.2 2.0 66 20.2-26.7 23.1 1.7 – Anal-fin base length 36.6 66 34.4-40.6 37.2 1.4 75 34.0-40.4 36.7 1.4 – Anal-fin lobe length 22.2 63 18.2-23.6 20.8 1.2 75 16.6-25.6 20.5 1.8 – Eye to dorsal-fin origin 46.2 66 44.3-48.5 46.3 1.1 75 42.7-49.0 45.8 1.5 – Dorsal-fin origin to caudal-fin base 45.0 66 41.2-47.4 44.1 1.6 75 40.6-45.5 43.1 1.2 – Bony head length 27.6 66 25.3-29.8 27.5 1.0 75 26.8-30.2 27.9 1.0 – Horizontal eye diameter 33.3 66 33.3-40.6 37.0 1.9 75 33.7-44.0 38.4 1.8 – Snout length 22.2 66 18.6-25.0 22.0 1.5 75 19.1-24.2 21.6 1.5 – Least interorbital width 35.6 66 32.1-39.7 35.8 1.8 75 30.6-39.5 35.5 2.1 – Upper jaw length 44.4 66 38.6-47.5 43.2 1.8 75 38.0-46.7 42.6 1.7 –

vertical through anterior border of eye.

Dorsal-fin unbranched rays ii in all specimens, branched rays 8-9 (8), 8.2, n = 127; posterior ray not split to its base and counted as 1 ray. Adipose fin elongate and slender. Principal caudal-fin ray count 10/ 9 in all specimens, n = 127. Fin rays modified in association with caudal pheromone pump as in Fig. 32 . Fin rays modified more like those in M. barberi and M. pulcher than other species of Mimagoniates (compare Figs. 32 , 38 and 47 ). Anal-fin unbranched rays iv or rarely v, branched rays 23-30 (28), 26.8, n = 127; posterior ray split to its base and counted as 1 ray. Anal fin barely showing anterior lobe ( Figs. 29 , 30 and 33 ).

Anal fin of sexually mature males with bilateral hooks, 1 on each side, on last unbranched ray ( Fig. 33 ). Usually anterior 6 branched fin rays with bilateral hooks, 1 set of hooks for each ray; occasionally 2 hooks per ray on a side but always only 1 hook per segment on a side. Pectoral-fin unbranched ray i in all specimens, branched rays 9-11 (9), 9.8, n = 127. Tip of pectoral fin extends beyond pelvic-fin origin. Pelvic fin rays i, 6 (branching of anterior, first ray variable in our population samples, i, 6 in 63 specimens, most under approximately 20 mm SL, but 7 in 64 specimens, most of them over approximately 20 mm SL), n = 127. Fig. 34 illustrates anterior branched pelvic ray. Total pelvic-fin rays 7 in all specimens examined, n = 127. Sexually mature, large adult males with over 260 minute to small sized hooks on each pelvic fin distributed as shown in Fig. 34 .

Scales cycloid, with few radii along posterior border. Terminal scale of modified caudal-fin series without exaggerated radii ( Fig. 32 ). Lateral line incomplete, perforated scales 5-8 (6), n = 79. Lateral series scales 34-41 (39), 38.2, n = 79. Predorsal scales 18-22 (18), 19.3, n = 8. Scale rows between dorsal-fin and anal-fin origins 15-18 (16), 16.0, n = 108. Scale rows around caudal peduncle 15-19 (16), 17.3, n = 59.

Premaxillary teeth tricuspid in all large specimens ( Fig. 35 ), smaller teeth sometimes bicuspid or conical in smaller specimens. Premaxillary teeth 6-9 (8), 7-9, n = 127 in a single row, usually tricuspid, occasionally one or two bicuspid or conical at posterior portion. Maxillary teeth ( Fig. 35 ) 3-10 (4), 4-6, larger specimens usually with higher counts, n = 127. Dentary with 4 large anterior tricuspid teeth, followed by smaller posterior teeth 4-12 (6), 6.1, anterior small dentary teeth of posterior row tricuspid, posterior ones conic, n = 124 ( Fig. 35 ). Smaller individuals tend to have fewer teeth than larger specimens. Maxillary and dentary teeth shaped much like premaxillary teeth.No significant difference in tooth number between sexes.

Vertebrae 36-39 (38), 37.9, n = 49. Dorsal limb gill rakers 5- 7 (6), 6.3, n = 127; ventral limb gill rakers 10-12 (11), 10.9, n = 127. Branchiostegal rays 4, in 9 cleared and stained specimens, 3 rays originating on anterior ceratohyal and 1 ray on posterior ceratohyal.

Color in alcohol. See Figs. 29 and 30 for color pattern of males and females. Body pale to medium brown, pale yellowish brown ventrally, darker dorsally. Lateral body stripe diffuse throughout body length in both sexes, consisting of scattered dark chromatophores of fairly large size, extending from black, vertical humeral spot posteriorly to caudal fin and onto dorsal region of ventral caudal-fin lobe and basal part of dorsal caudal-fin lobe. Scattered pigmentation darker in males than in females or immatures. Caudal gland structures, including those derived from dorsal caudal-fin lobe such as modified caudal squamation with scattered dark chromatophores. Caudal pigmentation much paler in females and immatures. Remainder of caudal fin dusky due to scattered dark chromatophores in both sexes, but darkest in adult males. Dorsal border of first principal caudal-fin ray and ventral border of nineteenth principal caudal-fin ray black. Humeral spot vertically elongate, especially dark in sexually mature males, dusky in females and immatures. Dorsal most surface of body black, forming narrow dark stripe extending from supraoccipital region to base of dorsal procurrent rays of caudal fin. Dorsal area of back also with scattered small chromatophores, much smaller than chromatophores of diffuse lateral stripe. Body surface ventral to lateral stripe pale brown due to scattered dark chromatophores comparable to those forming lateral stripe. Abdomen white or yellowish white, without dark chromatophores.

Pectoral, pelvic, dorsal, and anal fins dusky with scattered small dark chromatophores along fin rays and on membranes. Anal fin with distally located dark elongate stripe (darker in males) running length of fin. Stripe width about one-fourth height of anal fin. Sexually mature males with stripe somewhat darker anteriorly, especially dorsal to anterior anal-fin lobe. Dorsal-fin with horizontal dark stripe in adults extending posteriorly from about mid-length of anterior elongate divided ray to posterior tips of two terminal dorsal-fin rays. Stripe relatively narrow, usually less than one-eighth maximum height of dorsal fin. Width and intensity of stripe varies with sex and sexual maturity, darker in males but always paler anteriorly. Adipose fin dusky with scattered dark chromatophores, darker in mature males than females and immatures.

Head brown around mouth, darker and almost black on dorsal surface of snout, between eyes, dorsal portion of head and nape. Tip of lower jaw dark brown. Scattered fairly large dark chromatophores on head area posterior to infraorbitals on rays. Ventral lobe of caudal fin with considerable black pigment on rays in males, especially those rays radiating from caudal organ. Anal fin with distal portion of fin rays beyond dark anal-fin stripe hyaline to silvery yellow. Proximal portion of anal fin dorsal to black stripe, hyaline or with some silvery pigment.Approximately distal one-half of pelvic fin white with a black and reddish band proximal to this. Remaining proximal portion of pelvic fin hyaline. Distal one-half of pectoral fins pale lemon yellow. Dorsal fin hyaline to white both distal and proximal to black and brown longitudinal stripe.

Sexual dimorphism. Females lack the caudal pheromone organ ( Fig. 30 ), as well as the anal-fin and pelvic-fin hooks of males. Also females display more subdued live body coloration as noted above. Caudal peduncle depth and pelvic-fin length differ significantly between males and females ( Table 6). However, when these morphometric characters were compared as a function of standard length through regression analysis, no significant differences were found. The samples include, however, very few mature males and females.

and extending ventrally from parietal region, across dorsal opercular region pale with scattered fairly large dark chromatophores. Same color continues ventrally across posterior region of opercular bone to just reach interopercular bone. Iris dark brown dorsal to pupil, otherwise silvery or if silvery pigment absent dark, nearly black. Infraorbitals silvery if guanine preserved, pale yellowish brown when guanine absent. Dark brown chromatophores scattered evenly across circumorbital area.Anterior area of opercle, all of preopercle, and branchiostegal rays silvery or pale brown, with limited dark brown pigment.

Color in life. Life colors described here taken from a 35 mm color slide of specimen photographed just after capture from a blackwater stream ( USNM 236424 ). Sides of body pale silvery blue. Broad diffuse lateral body stripe somewhat deeper silvery blue from black humeral spot to termination of caudal peduncle. Back darker blue to blue green color immediately dorsal to silvery blue color of body sides. Dorsal region of caudal peduncle faint yellow. Ventral abdominal area, most of lower jaw, ventral opercular area, branchiostegal rays and their membranes silvery white. Dark pigment of head similar to that in preserved specimens. Top of head black. Dorsal caudal-fin lobe and principal caudal-fin rays 14-16 on ventral caudal-fin lobe mostly hyaline but with a little dark red color along dark stripe of dorsal fin. Dorsal lobe of caudal-fin mostly hyaline with little reddish pigment Distribution. Mimagoniates inequalis is known from small streams and rivers tributaries of rio Jacuí and lago Guaíba, from small streams flowing into laguna dos Patos, and from small isolated coastal ponds and streams flowing into the Atlantic Ocean in southern Rio Grande do Sul, Brazil. It was also collected in tributaries of the upper rio Negro, Rivera, Uruguay. See fig. 3 in Menezes et al. (2008) .

Ecology. Immatures of this species are found in small, slowly moving blackwater streams in forested regions and in areas with sufficient vegetation to produce mild to extremely dark tea colored waters. Somewhat acid water low in salts appears to be one of this species ecological requirements. This is one of the first fish species to disappear once streams are polluted. A few mature specimens over approximately 28.0 mm SL were found in the same blackwater streams occupied by the smaller specimens but large adult males of up to approximately 38 mm SL are rarely taken in the wild.

Remarks. The glandulocaudins examined and reported by Schultz (1959) need critical discussion to clear up some of the confusion of the species names used in the texts and for the photographs published by Axelrod (1958), Harald Schultz (1959), and L. P. Schultz (1959). The collecting trip reported by Axelrod (1958) where specimens of Mimagoniates were collected, was in the region near Santos, in the state of São Paulo. Axelrod (1958: 13-15) noted that Mimagoniates species identifications were questionable. Collections available to us from this region indicate that two species of Mimagoniates occur there, M. lateralis from blackwater streams and M. microlepis from clear water streams. Axelrod (1958: 15 and the color photograph on page 12) discussed and illustrated a species of Mimagoniates found in black acid waters identified as M. microlepis by Harald Schultz that we identify as M. lateralis . Axelrod (1958: 17) reported but did not illustrate another species, called Mimagoniates barberi (?) from open waters. This is possibly M. microlepis . A color photograph on page 13, illustrates two specimens identified as M. inequalis . The fish pictured at the left is probably an adult M. inequalis because the dark stripe on the anal fin does not closely approach the distal margin of the fin, especially anteriorly. The specimen at right is most probably an immature moderate-sized specimen of M. microlepis because the dark anal-fin stripe does closely approach the distal margin of the fin. Mimagoniates inequalis is unknown from the region near Santos and the photograph is likely one that Harald Schultz made of specimens collected in Rio Grande do Sul State. Axelrod (1959: 39) mentions collecting a species of Mimagoniates on another expedition, this time to Rio de Janeiro State, but no photographs or comments were made about the species. This species would be been M. microlepis , the only species to occur in this state according information at hand.

Harald Schultz (1959) discussed the species of Mimagoniates and Glandulocauda but seemed aware of only three species, M. barberi , M. microlepis and G. inequalis . In this publication Schultz recognized M. lateralis as M. barberi (the name often used at that time for M. lateralis in the European and American ornamental fish trade). The photograph labeled as of M. barberi is of M. lateralis . Schultz (1959) correctly gives the range of what he designates as M. barberi as found in blackwater streams from the city of Santos south to the State of Santa Catarina. This time he appears to have correctly identified M. microlepis and states that it is found in the coastal plains from north of Rio de Janeiro south to Paraná and Santa Catarina States, a range nearly equal to that recorded below for that species. Schultz (1959: 52) found G. inequalis (= M. inequalis of the present report) south of the range of M. microlepis in Rio Grande do Sul State. He found M. inequalis and M. microlepis only in clear water. Interestingly in regard to Menezes & Weitzmann (1990: 416-422) discussion of the possible hybrid origin of M. rheocharis, Schultz found both M. inequalis and M. microlepis living together. (see discussion under M. rheocharis ). A jar of 14 specimens of M. inequalis plus one of M. microlepis, USNM 177704 (all identified as M. inequalis by L. P. Schultz, 1959: 63), and said to be collected in Porto Alegre might tend to confirm this overlap in geographical range. There is no information that all these specimens are from one locality near Porto Alegre. The lot was entered into the USNM catalog on 4 February, 1959, and the fishes were collected sometime previous to that date.

Another sample of Mimagoniates, USNM 177703, listed as collected in Porto Alegre, and identified by Schultz (1959: 11) as M. microlepis , is rather M. lateralis . The known southern most locality for M. lateralis is Santa Catarina State, rio Vermelho, Barra do Sul in Ilha de São Francisco, about 35 km from Joinville, SC, 26°14’S 48°35’W, a location far from Porto Alegre, RS. This raises question to the locality information for USNM 177703 and 177704.

Material examined. Holotype. FMNH 54893, adult male, 32.6 mm SL; Brazil, Rio Grande do Sul, Porto Alegre, (rio Guaíba “in front of town” see Eigenmann, 1911a: 308), approximately 30°02’S 51°12’W. See notes below on type locality. Paratypes. Collected with holotype: FMNH 54894, immatures, 4, 21.6-25.6 mm SL; CAS (IUM) 13270, adult female, 29.8 mm SL, adult male, 31.5 mm SL. Non-Types. All collected in Brazil, Rio Grande do Sul, rio Guaíba basin: USNM 94310, adult males 3, adult female 1, 29.5- 41.5 mm SL, aquarium specimens reported to have been imported into Germany from PortoAlegre, Rio Grande do Sul; USNM 177704, immature to adults 14, 17.6-35.4 mm SL, Porto Alegre, (Schultz, 1959: 63 listed 15 specimens; largest specimen is M. microlepis ; see “Remarks” below under M. inequalis concerning locality information of lot); MCP 9892, adult females 2, 33.4-37.9 mm SL, município de Triunfo, “near rio Caí”, 30; MZUSP 75515, immature to adult 2, 24.7-32.2 mm SL, município de São Leopoldo, fazenda São Borja; MAPA 811, 40 young to adults, município Gravataí, tributary to rio Gravataí at Morungava (between Gravataí and Taquara) northeast of Porto Alegre, rio Gravataí flows into rio Jacuí near mouth of latter; USNM 313489 (erroneously MCP 9892 in Weitzman et al., 1988: 402), young to adult male, c&s, 24.4-37.0 SL, same data as MAPA 811; USNM 236423, small adults 38, 13.6-29.1 mm SL, município de Viamão, southeast of Porto Alegre, riacho Passo Comprido, a tributary to arroio Fiúza, approximately 30°10’S 51°00’W; USNM 257116, young to juveniles 42, 14.2- 22.4 mm SL, same locality data as USNM 236423; USNM 254273, young to juveniles 39, 15.9-26.6 mm SL, same data as USNM 236423; USNM 236424 (erroneously USNM 234161 in Weitzman & Fink, 1985: 106), young to maturing adults 34, 13.2-30.5 mm SL, município de Montenegro, arroio Passo da Cria along Passo da Serra near Montenegro, rio Caí drainage, 29°40’S 51°25’W; MZUSP 26908, young to adults 24, 14.3-24.6 mm SL, same locality data as USNM 236424; USNM 254275, young to adults 44, 16.0- 26.6 mm SL, município de São Sebastião do Caí, arroio Paradiso, on road between São Sebastião do Caí and Bom Princípio; USNM 236090, immatures to adults 5, 24.8-27 mm SL, c&s, same locality data as USNM 254275; MZUSP 19942, young to juveniles 55, 14.3-21.7 mm SL, same locality data as USNM 425275; MNRJ 26440, young to juveniles 52, 14.4-23.3 mm SL, same data as USNM 254275; USNM 254274, young to juveniles 30, 14.9-26.4 mm SL, município de Pelotas, arroio de Pelotas at bridge of road BR-116, north of Pelotas, approximately 31°39’S 52°19’W; USNM 254271, juvenile 1, 20.5 mm SL, município de Rio Grande, arroio Bolacha at crossing of road between Rio Grande and Cassino, 32°10’S 52°10’W; USNM 254270, young to juveniles 9, 17.9-23.0 mm SL, município de Rio Grande, north end of banhado do Tigre, from a small stream crossing the road between fazenda Caçapava and Estação Ecológica do Taim, approximately 32°36’S 52°37’W; UFRGS 3946, immatures to adults 11, 18.1-27.5 mm SL, lagoa Emboaba, Tramandaí; USNM 326754, immatures 2, 25.4-27.8 mm SL, canal between lagoa Emboaba and lagoa Emboabinha on the road to Osório-Tramandaí, near Tramandaí; MZUSP 83355 immatures 3, 16.0- 24.5 mm SL, tributary of rio Morungava in town of Morungava; USNM 326755, immatures to adults 4, 15.5, 26.8 mm SL, streams in município de Belém Novo, south of Porto Alegre. Uruguay, Rivera: USNM uncatalogued, immatures to adults 5, 21.2-32.0 mm SL, Cañado, 31º11’60”S 55º47’35”W by P. Laurino, T. Litz et al., 25 Aug. 2004; USNM uncatalogued, immatures to adults 9, SL 17.9-31.8 mm, 31º05’03”S 55º45’27”W.

Figures

Fig. 29. Mimagoniates inequalis, male, UFRGS 3946, 27.5 mm SL, Brazil, Rio Grande do Sul, lagoa Emboaba, Tramandaí.

Fig. 30. Mimagoniates inequalis, female, MAPA 811, 22.7 mm SL, Brazil, Rio Grande do Sul, tributary to rio Gravataí at Morungava.

Fig. 32. Mimagoniates inequalis, adult male, MCP 9892, 37.0 mm SL; osteology of caudal skeleton and caudal-fin squamation (lower left inset) lateral view, left side. Cartilage represented by crosshatching.

Fig. 38. Mimagoniates barberi, adult male, UMMZ 205420, 35.6 mm SL; osteology of central basal region of caudal skeleton, principal caudal-fin rays 6-15, lateral views, left side, anterior is at left. Principal ray 12 indicated by arrow. (a) Illustrates glandular groove between rays 11 and 12. (b) Illustrates relationship of modified dorsal caudal-fin lobe squamation to glandular groove. Modified scales together their epidermis form movable flap just lateral to surface of rays and groove that bear most of glandular tissue. Modified from Menezes & Weitzman (1990).

Fig. 47. Mimagoniates pulcher, developing male, MNRJ 4233, 34.2 mm SL; osteology of principal caudal rays 7-15, lateral view, left side, anterior at right.

Fig. 33. Mimagoniates inequalis, adult male, MCP 9892, 37.0 mm SL; anterior 12 anal-fin rays, lateral view, left side. First branched ray bears two hooks.

Fig. 34. Mimagoniates inequalis, adult male, MCP 9892, 37.0 mm SL; pelvic-fin rays, ventral view, left side.

Fig. 35. Mimagoniates inequalis, adult male, MCP 9892, 37.0 mm SL; jaws and dentition, lateral view, right side, anterior at left.