Gymnogeophagus peliochelynion, Turcati & Serra-Alanis & Malabarba, 2018

Turcati, Andréia, Serra-Alanis, Wilson Sebastián & Malabarba, Luiz R., 2018, A new mouth brooder species of Gymnogeophagus with hypertrophied lips (Cichliformes: Cichlidae), Neotropical Ichthyology 16 (4), pp. 1-9 : 2-6

Gymnogeophagus peliochelynion , new species

urn:lsid:zoobank.org:act:ECB36EC2-2EE7-438B-A9B4-F28FD3899154

Figs. 1-5

Holotype. ZVC-P 12493, male, 101.9 mm SL, Uruguay, Salto, arroyo de las Tunas on Ruta 31, tributary to río Arapey Grande , 31°20’4.87”S 57°19’36.42”W, 8 Sep 2005, V. Bertaco, F. Cantera, J. Ferrer & L. R. Malabarba.

Paratypes. Uruguay, Departamento de Salto. Río Arapey drainage: MHNM 3711 , 4 , 1 male 79.9 mm SL, 3 females or juveniles 50.0- 69.5 mm SL, río Arapey Chico on Ruta 4, 31°2’7.44”S 56°53’50.21”W, 22 Nov 2005, F. Teixeira, A. D’Anatro, I. González, S. Oviedo & M. Loureiro. UFRGS 8042 , 7 , 2 males 93.1-106.1 mm SL and 5 unsexed juveniles 19.7-64.1 mm SL, tributary stream to río Arapey Grande on Ruta 4, 31°07’44.0”S 56°59’57.0”W, 8 Sep 2005, V. Bertaco, F. Cantera, J. Ferrer & L. R. Malabarba. UFRGS 8076 , 14 , 3 males 99.7-100.1 mm SL (1 c&s 74.2 mm SL), 2 females 74.3-77.2 mm SL and 9 unsexed juveniles 51.2-67.1 mm SL (1 c&s 40.8 mm SL), collected with the holotype. UFRGS 8101 , 1 , female 70.3 mm SL, stream on Ruta 4, tributary of stream Valentin Grande, 31°16’32.0”S 57°09’22.0”W, 8 Sep 2005, L. R. Malabarba, V. Bertaco, J. Ferrer & F. Cantera. ZVC-P 13084, 4, 2 males, 76.4-79.7 mm SL, 2 females or juveniles 46.4-55.6 mm SL, Cañada de la Tapera, tributary of río Arapey , 31°09’02.15”S 56°13’25.18”W, 13 Dec 2014, M. Loureiro, A. Duarte, S. Serra, J. Bessonart & S. Paullier. ZVC-P 13210, 1 male 76.3 mm SL, río Arapey , Colonia Lavalleja, Paso Elías, 31°02’50.94”S 57°00’46.04”W, 17 Dec 2014, M. Loureiro, A. Duarte, S. Serra, J. Bessonart, S. Paullier .

Non-types: Uruguay, Departamento de Salto. Río Arapey drainage: ZVC-P 7016, 16, 43.3-94.1 mm SL, Río Arapey Chico, Ruta 4, 31°02’07.44”S 56°53’50.21”W, 22 Nov 2005, F. Teixeira, A. D’Anatro, I. González, S. Oviedo & M. Loureiro. ZVC-P 12656, 3, 48.9-59.0 mm SL, Arroyo Sopas, Paso del Cementerio , 31°23’34.21”S 56°42’31.06”W, 13 Aug 2013, M. Loureiro, J. Bessonart, S. Serra & L. Montes de Oca. ZVC-P 12715, 4, 44.6-61.6 mm SL, Arroyo Sauce del Arapey , 31°19’27.25”S 56°37’24.55”W, 11 Aug 2013, M. Loureiro, J. Bessonart, S. Serra & L. Montes de Oca. ZVC-P 13013, 1, 51.7 mm SL, Arroyo Mataperros, 30°58’47.46”S 56°23’15.60”W, 15 Dec 2014, M. Loureiro, A. Duarte, S. Serra, J. Bessonart & S. Paullier. ZVC-P 13043, 4, 43.9-59.4 mm SL, Arroyo Arerunguá, Paso del Potrero , 31°27’07.02”S 56°50’37.01”W, 18 Dec 2014, M. Loureiro, A. Duarte & S. Serra. ZVC-P 13057, 2, 65.3-90.2 mm SL, Arroyo Sopas, Paso del Cementerio , 31°23’34.21”S 56°42’31.06”W, 18 Dec 2014, M. Loureiro, A. Duarte & S. Serra. ZVC-P 13079, 3, 57.6-77.1 mm SL, Arroyo Mataojo, Pueblo Fernandez, 31°10’37.01”S 56°21’56.54”W, 14 Dec 2014, M. Loureiro, A. Duarte, S. Serra, J. Bessonart & S. Paullier. ZVC-P 13118, 6, 56.3-77.2 mm SL, Río Arapey , Picada Sarandí, 31°03’52.47”S 56°22’44.84”W, 15 Dec 2014, M. Loureiro, A. Duarte, S. Serra, J. Bessonart & S. Paullier. ZVC-P 13139, 2, 52.7-57.7 mm SL, Arroyo Mataojo Grande, Paso de la Herrería, 31°11’45.40”S 56°36’11.65”W, 14 Dec 2014, M. Loureiro, A. Duarte, S. Serra, J. Bessonart & S. Paullier. ZVC-P 13178, 3, 51.2-55.9 mm SL, Río Arapey , Colonia Lavalleja, Paso Elías, 31°02’50.94”S 57°00’46.04”W, 16 Dec 2014, M. Loureiro, A. Duarte, S. Serra, J. Bessonart & S. Paullier .

Diagnosis. The new species can be distinguished from the species of the Gymnogeophagus rhabdotus group and from G. balzanii by the shape of the caudal peduncle longer than deep (vs. deeper than long). It is distinguished from all congeners, except G. labiatus and G. pseudolabiatus , by the possession of thick lips. It differs from G. labiatus and G. lacustris by the lack of an oblique bar from the eye to the dorsal-fin origin (vs. oblique bar present), and by the color pattern of the caudal, dorsal and anal fins with dots (vs. caudal fin and posterior portion of anal fin with longitudi- nal hyaline stripes). It differs from G. pseudolabiatus and G. mekinos by the hump entirely black in males ( Fig. 2 ; vs. yellow with black margin), and upper lip not folded dorsally over anterior margin of snout (vs. upper lip folded dorsally, usually with a well-developed medial lobe dorsally projected in G. pseudolabiatus ).

Description. Standard length of specimens examined 19.2 to 106.1 mm. Morphometric data summarized in Tab. 1 . Body elongated, laterally compressed. Dorsal profile of head slightly convex between mouth and interorbital area in young and females, slightly straight in males; slightly convex from interorbital region to dorsal-fin origin. Reproductive males with adipose hump from interorbital region to dorsal-fin origin; dorsal-fin base gently convex. Caudal peduncle rec- tangular, longer than deep, with slightly concave dorsal and ventral profiles. Prepelvic contour straight to slightly con- vex; abdominal contour straight and base of anal fin straight to slightly convex.

Head depth larger than head length. Snout triangular in lateral aspect; slightly rounded anteriorly, pointed in dorsal aspect. Eyes small, close to dorsal profile of head in juveniles and progressively farther from it in larger specimens (about eye diameter in specimens up to 80 mm); eyes near middle of head length. Interorbital area slightly convex in young and female, and deeply convex in large males; interorbital width larger than eye diameter, except in individuals smaller than 25 mm. Mouth terminal. Posterior tip of maxilla not reaching vertical line across anterior margin of eyes. Upper jaw slightly longer than lower jaw; lips developed, lower lip thicker than upper lip; margin of lower lip convex, deeper in middle length of each dentary, deeply notched medially at symphysis. Snout longer than postorbital length, except in individuals up to 48 mm SL.

Body scales moderately large and ctenoid, smaller ctenoid scales in preventral area. Proximal third to half of cau- dal fin with small elongated cycloid scales in single series between contiguous rays. Dorsal fin without scales. Cheek naked. Small cycloid scales on opercle. Subopercular scales ctenoid in 1-2 irregular rows. Ctenoid scales on base of hump (in adult reproductive males only) to approximately vertical line passing on anterior margin of eye. Scales in longitudinal series 26*(5), 27(6), 28(3). Anterior lateral line 15(1), 17*(8), 18(5). Posterior lateral line 8*(4), 9 (6), 10(1), 11(2), 12(1). Scales between anterior lateral line and dorsal fin 6*(12), 7(2). Scales between anterior lateral line and anal fin 8*(11), 9(3).

Dorsal-fin spines 12(1), 13(2), 14*(11); dorsal-fin soft rays 9(1), 10*(11), 11(2). First dorsal-fin spine inserted right above vertical line across posterior bony margin of opercle. Soft dorsal fin slightly pointed in young and adult females, reaching or almost reaching caudal-fin base. Fourth or fifth dorsal-fin soft ray longest in mature males, reaching proximal two third to half of caudal-fin length. Three analfin spines; anal-fin soft rays 8*(11), 9(3); anal-fin profile rounded in young and females, reaching or almost reaching caudal-fin base; slightly pointed in reproductive males, sur- passing caudal-fin base. Pectoral fin with pointed tip, reach- ing or almost reaching anal-fin origin in juveniles and fe- males and surpassing anal-fin origin in reproductive males. Pelvic fin slightly pointed; second soft ray longest, reaching anal-fin base in mature males. Caudal-fin margin concave.

Jaw teeth small, conical, with recurved tips. Upper jaw with outer regular row of 16-26 teeth in each premaxilla (number increasing with specimen size) and two irregular internal rows of slightly smaller teeth. Lower jaw with 3-5 irregular rows of small conical teeth; outer hemiseries with 20-28 teeth. Lower limb of first gill arch with 6-10 gill rakers; upper limb lobed with 3-4 gill rakers in its margin. Lower pharyngeal tooth plate wide; teeth covering whole occlusion surface. Teeth on medial rows larger than remaining ones. Posterolateral teeth elongated; posteromedial teeth larger, cylindrical with medial, blunt cusps of molariform aspect ( Fig. 3 ).

Coloration after fixation in formalin. ( Fig. 4 ) Mature males: ground color of body dark brown above longitudinal series of scales of posterior lateral line and light yellowish brown below. Series of double vertical bars clearly discernible along midventral lateral surface of flanks, distributed be- tween pectoral-fin base and end of caudal peduncle, anterior to caudal-fin base. Number of vertical double dark bars 5-6. Midlateral spot without defined borders. Hump entirely black in males making dark band in front of dorsal-fin origin hardly detectable. Head dark brown with some black spots on cheek and near posterior margin of opercle; dark band covering cheek hardly distinct. Isthmus and branchiostegal membranes dark brown. Pectoral fin hyaline. Pelvic fin dark gray. Spi- nous dorsal fin dark brown; soft dorsal fin light brown with circular dots. Distal one third of anal-fin rays and spines dark brown, without additional marks. Two proximal thirds of anal-fin rays covered with small circular dots. Caudal fin co- vered with white dots, except near upper and lower borders.

Color in alcohol of preserved females and young not distinct from that described for males. Main differences are: isthmus and branchiostegal membrane yellow; clearly distinct dark band covering cheek, below eye; distinct dark band on dorsal-fin origin; and larger size of white spots on dorsal, anal, and caudal fins.

Coloration in life. ( Fig. 5 ) Ground color of dorsal profile golden or dark olivaceous with longitudinal series of light blue spots. Well defined black, circular midlateral spot, cove- ring scales 9-11 of the anterior lateral line, scales 10-12 of the scale row just below anterior lateral line and scales 8-10 of the next scale row below. Large dark bar below eye, usually not reaching midline of mouth in larger individuals. Numerous small bright blue spots usually present on cheeks. Red marks on cheeks usually present in mature males, concentrated on upper portion of opercle and preopercle, region behind eye and above pectoral fin. Usually grayish blue lips in repro- ductive males and gray in females and young. Adipose hump, when present, black. Ventral portion of body light olivaceous to yellow pale in mature males with longitudinal series of light blue spots. Spinous dorsal fin and base of soft dorsal fin yellowish brown; most soft dorsal fin red with relatively lar- ge and numerous hyaline dots. Distal tip of dorsal fin hyaline. Pectoral fin hyaline and pelvic fin dark orange to dark gray with light blue spots at base. Anal fin yellowish orange pro- ximally with numerous clear spots and hyaline on half distal portion with dark gray margin. Caudal fin yellowish brown with numerous light spots, extending along middle of caudal fin; dorsal and ventral portions of fin hyaline.

Geographic distribution. This species is known from the río Arapey Grande drainage, a tributary of the lower río Uruguay basin, Uruguay ( Fig. 6 ).

Ecological notes. The new species was collected in rivers with clear water, usually with rocky or muddy bottom and little vegetation.

Etymology. The name peliochelynion is from the Greek pelios, meaning black and blue, and chelyne, meaning lip, in reference to the color of the lips of the new species. A name in apposition.

Conservation status. Gymnogeophagus peliochelynion is relatively frequent and abundant in the río Arapey Grande drainage. No specific threats were detected, and the spe- cies can be categorized as Least Concern (LC) according to IUCN criteria (IUCN, 2016).

Figures

Fig. 1. Anterior portion of dorsal-fin skeleton of Gymnogeophagus peliochelynion (anterior towards left), UFRGS 8076, paratype, 74.2 mm SL. Arrow indicates the anterior spine in the first dorsal pterygiophore. Note the lack of su- praneurals between supraoccipital and first dorsal pterygiophore.

Fig. 2. Head of Gymnogeophagus peliochelynion (first column), G. pseudolabiatus (second column) and G. mekinos (third column) showing the entirely black hump in males in G. peliochelynion (vs. yellow with black margin), and upper lip not folded dorsally over anterior margin of snout (vs. upper lip folded dorsally in G. pseudolabiatus and undeveloped in G. mekinos). G. peliochelynion from top to bottom, paratype, ZVC-P 13210, paratype, 76.3 mm SL; ZVC-P 7016, 89.9 mm SL; ZVC-P 13057, 90.2 mm SL. G. pseudolabiatus from top to bottom, paratype, UFRGS 7754, 102.0 mm SL; MHNM 4010, 88.8 mm SL; MHNM 4010, 95.3 mm SL. G. mekinos from top to bottom, MHNM 3511, 105.1 mm SL; MHNM 3511, 97.2 mm SL; MHNM 4009, 121.3 mm SL.

Fig. 3. Pharyngeal tooth plate of Gymnogeophagus peliochelynion, 74.2 mm SL, UFRGS 8076, paratype. Dorsal view; anterior to bottom.

Fig. 4. Gymnogeophagus peliochelynion: top, holotype, male, ZVC-P 12493, 101.9 SL; bottom, paratype, female, UFRGS 8076, 77.2 SL. Both from arroyo de las Tunas on road 31, tributary of río Arapey Grande, Salto, Uruguay. Photographs taken just after collection and fixation in formalin.

Fig. 5. Gymnogeophagus peliochelynion: above, paratype, male, ZVC-P 13210, paratype, 76.3 mm SL, río Arapey, Colonia Lavalleja, Paso Elías, Salto, Uruguay; below, female, ZVC-P 13057, 65.3 mm SL, Arroyo Sopas, Paso del Cementerio, Salto, Uruguay. Photographs of live specimens.

Fig. 6. Geographic distribution of Gymnogeophagus peliochelynion (yellow; star refers to type-locality), G. cf. peliochelynion (orange) and other species of the Gymnogeophagus gymnogenys clade: G. lipokarenos (blue), G. constellatus (green), G. missioneiro (red), G. tiraparae (white), G. mekinos (black), G. pseudolabiatus (pink) in the río Uruguay basin. Records of Gymnogeophagus lipokarenos and Gymnogeophagus constellatus from Argentina (triangles) are based on Casciotta et al. (2017b) and Říčan et al. (2017), respectively.

Tables

Tab. 1. Morphometric data of Gymnogeophagus peliochelynion, new species. Standard length is expressed in mm. Range includes measurements of holotype and 22 paratypes, except individuals smaller than 45 mm SL.

	Holotype	Min	Max	Mean	SD
Standard length (mm)	101.9	46.42 106.08		73.87	-
Percent of standard length
Head length	38.3	35.0	39.2	36.8	1.07
Body depth	38.5	33.8	39.9	37.7	1.44
Dorsal-fin base length	48.2	45.4	54.1	50.3	2.05
Pectoral-fin length	33.6	30.1	39.3	34.4	3.19
Caudal peduncle depth	13.2	11.9	14.2	13.3	0.52
Caudal peduncle length	15.1	14.0	18.1	15.3	1.10
Percent of head length
Eye diameter	21.3	20.2	32.3	25.1	3.27
Interorbital width	28.5	24.6	32.4	28.0	1.97
Upper jaw length	26.7	19.7	29.7	23.5	3.39
Pre-orbital length	33.4	26.9	36.6	30.7	2.83
Snout length	57.7	30.5	59.7	46.4	7.64