Gymnogeophagus missioneiro, Malabarba & Malabarba & Reis, 2015

Malabarba, Luiz R., Malabarba, Maria Claudia & Reis, Roberto E., 2015, Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage, Neotropical Ichthyology (Neotrop. Ichthyol.) 13 (4), pp. 637-662 : 651-653

Gymnogeophagus missioneiro , new species u r n:l s i d:z o o b a n k. o rg:a c t: 5C F 8 7 9 8 C -A9 C1-4 4 9 2-9E0 8- 42A12A8D7BDF

Figs. 6d , 10

Gymnogeophagus sp. D . - Wimberger et al., 1998 (molecular phylogeny).

Holotype. MCP 23495 , male, 109.3 mm SL, Brazil, Rio Grande do Sul, 4 km from São Luiz Gonzaga, arroio Ximbocuzinho, on road from São Luiz Gonzaga to Bossoroca , approx. 28°27’S 54°58’W, 11 Dec 1992, P. H. Wimberger, R. E. Reis, J. F. P. Silva & C. S. Fontana.

Paratypes. Brazil: Rio Grande do Sul: MCP 16125 (17, 16.6- 75.8 mm SL) , UMMZ 225488 (7, 52-77 mm SL), collected with the holotype . MCP 10881 (2, 65.5-125.3 mm SL), rio Piratini at Coimbra district, Santo Ângelo , approx. 28°42’S 54°25’W, 19 Dec 1985, L. R. Malabarba, R. E. Reis & S. B. Mallmann . MCP 12618 (12, 36.6-108.3 mm SL), arroio Canoin, on road from Pirapó to São Nicolau , approx. 28°08’S 55°14’W, 2 Nov 1988, C. A. Lucena, L. A. Bergmann, E. H. Pereira and others . MCP 12725 (10 alc., 2 c&s, 46.7-109.1 mm SL), arroio Passo do Rosário or Passo da Cancela, on road from São Nicolau to Garruchos , Santo Antônio das Missões , approx. 28°13’S 55°30’W, 3 Nov 1988, C. A. Lucena, P. Azevedo, L. A. Bergmann & E. H. Pereira .

Diagnosis. Gymnogeophagus missioneiro differs from congeners, G. balzanii , G. meridionalis , G. rhabdotus , G. setequedas , G. labiatus and G. lacustris by the absence of an oblique dark band from the eye to the origin of the dorsal fin. Gymnogeophagus missioneiro differs from the remaining species by the absence of an oblique dark band from the eye to the anterior border of the head in mature males (vs. present in G. gymnogenys and G. mekinos ); the unpaired fins colored red (vs. yellow in G. lipokarenos ); soft dorsal fin rarely scaled (vs. soft dorsal fin scaled in G. australis ); the presence of large white dots sometimes forming stripes distally in the soft dorsal fin (vs. dorsal fin of males with spaced small silvery to bright blue dots in G. caaguazuensis , and dorsal fin of males with three longitudinal bands colored of yellow proximally, white/red at middle length of dorsal fin spines and rays and dark gray distally in G. tiraparae ); the caudal fin covered with white dots (vs. caudal fin covered with dots proximally and stripes distally in G. constellatus ); and the lips not developed (vs. lips developed in G. pseudolabiatus ).

Description. Morphometric data summarized in Table 4. Body elongate, laterally compressed. Dorsal profile of head convex between mouth and interorbital area in young, slightly convex or straight in adults; convex from interorbital region to dorsal-fin origin. Predorsal body profile modified in adult males by small adipose hump ( Fig. 10a, b ). Dorsal-fin base slightly convex. Caudal peduncle longer than deep, with dorsal and ventral profile slightly concave.

Snout pointed, slightly blunt and rounded dorsally in young; mostly straight dorsally and ventrally in adults; narrow and anteriorly rounded in dorsal aspect. Eye small, close to dorsal profile of head in juveniles and progressively farther in larger specimens (about one half eye diameter in specimens larger than 70 mm SL); eye slightly posterior or near middle of head length. Interorbital area convex, more strongly so in larger specimens; interorbital width smaller than eye diameter in young (up to 50 mm SL) and progressively larger than eye diameter in larger specimens. Posterior tip of maxilla not reaching to vertical line across anterior margin of eye. Upper jaw slightly longer than lower jaw.

Body scales large and ctenoid, smaller around pectoral fins; scales cycloid in preventral area. Caudal fin with single series of small ctenoid and elongated scales between contiguous rays reaching one half length of fin in both upper and lower lobes. Soft portion of dorsal fin of males without scales between contiguous rays. Cheek scales cycloid in 5 or 6 rows; cheek naked anteroventrally. Opercle mostly scaled, especially dorsally. Subopercular scales ctenoid in one or two irregular rows. Upper lateral line 13(1), 15(1), 16(1), 17(3), 18*(2), 19(1). Lower lateral line 5(1), 8(4), 9(2), 11*(1), 12(1), with 1 to 3 small perforated scales continuing onto caudal-fin base. Scales between upper lateral line and dorsal fin 4*(4), 5(5). Scales between upper lateral line and anal fin 8*(3), 9(6). E1 scales 26(3), 27*(5), 28(1).

Dorsal-fin spines 13(3), 14*(4), 15(2); dorsal-fin soft rays 10*(7), 11(2). First dorsal-fin spine inserted at or slightly anterior to vertical line across posterior bony margin of opercle. Soft dorsal fin in young rounded, slightly pointed in adult females, reaching or almost reaching caudal-fin base. Soft dorsal fin in mature males pointed, with 3rd or 4th ray longest, reaching proximal third to one half length of caudal fin. Anal-fin with three spines and 8(8) or 9*(1) soft rays. Anal-fin origin under last dorsal-fin spine; soft portion nearly rounded in young and females and clearly pointed in males. Pectoral fin with rounded tip in young and slightly pointed in adults; 3rd and 4th rays longest, reaching to or slightly passing vertical crossing anal-fin origin. Pelvic fin pointed, more conspicuously so in adult males; 2nd soft ray longest reaching area between anal opening and anal-fin origin in both males and females, sometimes passing anal-fin origin in mature males. Caudal-fin margin truncated or slightly concave.

Jaw teeth small, conical, recurved. Upper jaw with irregular outer row of 18-24 teeth in each premaxilla (number increasing with specimen size). Anterior tip of lower jaw wide, tooth band arranged in 5 or 6 irregular rows; middle and posterior tooth band slender, arranged in 3 or 4 irregular rows. Teeth at anterior tip of dentary thicker than other dentary and premaxillary teeth. Nearly 18 teeth in outer hemiseries. Lower limb of first gill arch with 7-8 gill rakers; upper limb lobed with 4-7 gill rakers on its margin.

Lower pharyngeal tooth plate slightly wider than long; length of bone 96% of width; dentigerous area covering whole occlusion surface; 19 teeth in posterior row, 17 on median row. Lateral marginal teeth smaller on caudal half of plate; posteromedial teeth much larger, cylindrical with medial, blunt cusps of molariform aspect ( Fig. 6d ).

Vertebrae 13+ 16 in two cleared and stained specimens.

Color in alcohol. Mature males ( Fig. 10a ): ground color of body pale brown above longitudinal series of scales bearing lower lateral line, becoming yellowish below pectoral-fin insertion and in preventral area. Vertical bars clearly discernible along midventral surface of body, between pectoral-fin base and caudal peduncle, not discernible in caudal peduncle. Midlateral spot on scales 8-11 of upper lateral line and on two scale rows below upper lateral line. Dark band in front of dorsal-fin origin small, extending ventrally and slightly posteriorly. Head light brown, with series of dark gray markings ventral and posterior to eye and on opercle; dusky on snout and hump. Dark band covering cheek absent. Isthmus and branchiostegal membrane pale brown. Pectoral fin hyaline; pelvic fin light brown. Spinous dorsal fin and anterior portion of soft dorsal fin faint brown with narrow white stripes. Posterior portion of soft dorsal fin faint brown covered with relatively large circular white spots. Proximal two thirds of anal-fin rays with white dots. Distal third of anal fin rays and spines dark brown, without additional distinct marks. Caudal fin faint brown with circular white dots along its entire length. Color in alcohol of preserved females ( Fig. 10b ) and juveniles similar to that of males, but vertical bars hardly discernible. Isthmus and branchiostegal membrane light yellow, and pelvic fins hyaline.

Color in life. Ground color of dorsal region of body in males ( Fig. 10c ) olivaceous with longitudinal series of bright spots. Head largely brownish green with irregular red markings on opercle and immediate posterior area. Adipose hump brown, but darker than head. Vertical bars hardly discernible. Head with series of light blue dots under and posteriorly to eye, on opercle and preopercle. Lateroventral portion of body dark yellow, more intense around pectoral-fin base; yellow pale to gray along isthmus and prepelvic region. Dorsal fin red covered with light roundish spots proximally and light stripes distally. Caudal fin red entirely covered with light roundish spots aligned between rays. Anal fin orange on base, red in middle and dusky in distal portion. Pectoral fins hyaline; pelvic fins darkly pigmented.

Distribution. Gymnogeophagus missioneiro is known from the rio Piratini and its tributaries, middle rio Uruguay basin, in the western portion of Rio Grande do Sul, Brazil ( Fig. 1 ).

Etymology. Missioneiro, a Portuguese noun meaning from the Missões region, the Jesuitic Missions of the Eighteenth century in southern Brazil and Argentina, in allusion to the distribution of this species. A noun in apposition.

Conservation status. Gymnogeophagus missioneiro used to be relatively abundant but not very frequent in the rio Piratini basin until about 20 years ago. Recent collecting efforts in the area, including the type and paratype localities, failed to catch additional specimens. Its Extent of Occurrence (EOO) is approximately 1,200 square kilometers, and there is a significant continued decline in habitat quality by the extensive agriculture in the rio Piratini basin, both by pesticide runoff and siltation. On the other hand, the population is neither severely fragmented nor presenting extreme fluctuations, and the species is thus categorized as Near Threatened (NT) according to IUCN criteria ( IUCN, 2014).

Figures

Fig. 6. Lower pharyngeal tooth plates in occlusal view: a, G. pseudolabiatus, MCP 11228, 71.6 mm SL; b, G. mekinos, MCP 11251, 84.2 mm SL; c, G. constellatus, MCP 10827, 91.4 mm SL; d, G. missioneiro, MCP 12725, 59.3 mm SL; e, G. lipokarenos, MCP 12991, 89 mm SL. Scale bars = 1 mm.

Fig. 10. Gymnogeophagus missioneiro: top, holotype, male, MCP 23495, 109.3 mm SL, arroio Ximbocuzinho, on the road from São Luiz Gonzaga to Bossoroca, 4 km from São Luiz Gonzaga, Rio Grande do Sul, Brazil; middle, paratype, female, MCP 12725, 72.8 mm SL, arroio Passo do Rosário or Passo da Cancela, on the road from São Nicolau to Garruchos, Santo Antônio das Missões, Rio Grande do Sul, Brazil; bottom, holotype, photo taken just after capture.

Fig. 1. Rio Uruguay and adjacent drainages showing the distribution of the examined specimens of Gymnogeophagus lipokarenos (dark blue), G. missioneiro (light blue), G. constellatus (red), G. pseudolabiatus (orange), and G. mekinos (yellow). Stars represent the type localities.