aqua, International Journal of Ichthyology

Description of two new species of the zygonectes species group (: Cynolebiidae) from Rio Xingu and Rio Tapajós basins, Brazil

Dalton Tavares Bressane Nielsen

Laboratório de Zoologia, departamento de Biologia, Universidade de Taubaté, Av. Tiradentes180, CEP 12030-180, Taubaté, SP, Brazil. E-mail: [email protected]

Received: 31 March 2017 – Accepted: 10 April 2017

Keywords Resumo Melanorivulus canesi, Melanorivulus britzkei, Melanorivu- Duas novas espécies do gênero Melanorivulus são de- lus kayabi, Serra do Cachimbo, key to species. scritas, ambas pertencentes ao grupo de espécies Melanorivulus zygonectes. Melanorivulus canesi n.sp. é en- Abstract contrada em um tributário da bacia do médio Rio Xingu Two new species of the Melanorivulus are de- basin, estado do Pará, Brasil. Ela difere das demais espécies scribed, both belonging to the Melanorivulus zygonectes do grupo de espécies Melanorivulus zygonectes por seu species group. Melanorivulus canesi n.sp. is found at a trib- padrão de colorido, com machos apresentando colorido utary of the middle Rio Xingu basin, Pará, state of Brazil. verde metálico nos flancos. Melanorivulus britzkei n.sp. é It differs from the other species of the Melanorivulus zy- encontrada em um tributário de margem direita da bacia gonectes species group by its color pattern, with males pre- do médio Rio Tapajós, estado do Pará, Brasil. Ela difere das senting metallic green color at body sides. Melanorivulus demais espécies do grupo de espécies Melanorivulus zy- britzkei n.sp. is found at a tributary of the right bank in the gonectes pela presença em machos de um padrão de colori- middle Rio Tapajós basin, Pará state, Brazil. It differs from do amarelo metálico na cabeça e pela nadadeira pélvica the other species of the Melanorivulus zygonectes species branca. Uma chave das espécies pertencentes ao grupo de group by males presenting a yellow metallic color pattern espécies Melanorivulus zygonectes é apresentado. in the head and by a white pelvic fin. A key to the species belonging to the Melanorivulus zygonectes species group is Résumé presented. Deux nouvelles espèces du genre Melanorivulus sont décrites, appartenant toutes deux au groupe d’espèces Zusammenfassung Melanorivulus zygonectes. Ontouve Melanorivulus canesi Beschrieben werden zwei neue Arten der Gattung n. sp. dans un tributaire du moyen Rio Xingu, Para, état Melanorivulus, die beide zur Melanorivulus-zygonectes- du Brésil. Il se distingue des autres membres du groupe Artengruppe gehören. Melanorivulus canesi n.sp. findet d’espèces Melanorivulus zygonectes par son patron de col- sich im Zuflussgebiet des mittleren Rio Xingu im Staat oration, avec les mâles présentant du vert métallique sur les Pará Brasiliens. Die Vertreter dieser neuen Art unterschei- flancs. Melanorivulus britzkii n. sp. habite un tributaire den sich von anderen Arten der Gruppe durch ihr Farb- rive droite du moyen Rio Tapajos, état de Para, Brésil. Il muster: die Männchen zeigen eine metallisch grüne Farbe diffère des autres membres du groupe d’espèces an den Flanken. Melanorivulus britzkei n.sp. findet sich in Melanorivulus zygonectes par les mâles qui ont une couleur einem Nebenfluss rechts vom mittleren Rio Tapajós, Staat jaune métallique sur la tête et une pelvienne blanche. Une Pará, Brasilien. Die Angehörigen dieser neuen Art unter- clé concernant le groupe d’espèces Melanorivulus zygonectes scheiden sich von den anderen Arten der Artengruppe est fournie. dadurch, dass die Männchen ein metallisch gelbes Farb- muster am Kopf und eine weiße Bauchflosse präsentieren. Sommario Angefügt wird hier ein Bestimmungsschlüssel der Arten Sono qui descritte due nuove specie del genere Melano - der Melanorivulus-zygonectes-Artengruppe. , entrambe appartenenti al gruppo specie M. zygo -

55 aqua vol. 23 no. 2 - 28 April 2017 Description of two new species of the Melanorivulus zygonectes species group from Rio Xingu and Rio Tapajós basins, Brazil nectes. Melanorivulus canesi n. sp. è stato rinvenuto in un af- tion composed mostly by grasses and sedges, with fluente del bacino medio del Rio Xingu, nello stato di Pará, buriti palms (Mauritia flexuosa) and a few other Brasile. Si differenzia dalle altre specie del gruppo per la sua trees adapted to hydromorphic soils occur. colorazione, con i maschi che presentano fianchi metallici The Melanorivulus zygonectes species group was di colore verde. Melanorivulus britzkei n. sp. è stato cattura- to in un affluente della riva destra del bacino medio del Rio defined originally by Costa (2007), and was recent- Tapajós, nello stato di Pará, in Brasile. Si differenzia dalle al- ly reviewed by the same author (Costa 2016). The tre specie del gruppo per i maschi che presentano una colo - species belonging to this clade are found in the razione giallo metallico sulla testa e le pinne pelviche transitional area between the Amazon rain forest bianche. È presentata una chiave di riconoscimento delle and the Cerrado savannah, in central and north- specie appartenenti al gruppo M. zygonectes. eastern Brazil (Costa 2016). A single species be- longing to this group, M. parnaibensis, is found INTRODUCTION outside the Amazon basin, at the Rio Parnaíba in The genus Melanorivulus present a wide geo- northeastern Brazil, which suggests a historical bio- graphical distribution in central South America. geographic relationship between Southern Ama- Almost all of its species are found in Brazil, with zonian tributaries and this latter river basin only one species, M. punctatus, being recorded also (Nielsen & Pinto 2015). for Paraguay, Argentina, and Bolivia. The genus The present contribution aims to describe two Melanorivulus was originally erected as a subgenus additional species belonging to the Melanorivulus of Rivulus by Costa (2006a). Costa (2011) elevated zygonectes species group, one from the middle Rio Melanorivulus to the generic level. Xingu basin and the second one from the middle Most of the known Melanorivulus species occur in Rio Tapajós basin, both within the Amazon forest the Cerrado domain, which extends across most of domain, Pará state, Brazil. the central area of Brazil. At the Cerrado domain lies the headwaters of several hydrographic basins MATERIAL AND METHODS such as the rio Araguaia, Rio Tocantins, Rio Xingu, Measurements were taken point-to-point under a Rio Tapajós, Rio São Francisco, Rio Paraná, Rio stereomicroscope with a digital caliper to the near- Paraguai, and Rio Parnaíba basins. In addition to est 0.1 mm on the left side of the specimen follow- the Cerrado domain, some Melanorivulus species ing Costa (1995). Measurements are expressed as are also found at the Caatinga, Atlantic Forest, and percents of standard length (SL), except subunits Amazon domains. of the head, which are recorded as percents of head Only recently Melanorivulus species have been length (HL). Descriptions of color patterns were found at the Amazon Forest domain, namely, M. based on photographs of both sides of live individ- albae (Valdesalici et al. 2011) and M. schunki (Cos- uals of each species, taken in small aquaria one day ta & De Luca 2011), both from the lower Amazon after collection; color patterns derived from distri- basin system. Two Melanorivulus species are known bution of melanophores on fins were also observed from northeastern Brazil, Melanorivulus decoratus in all preserved specimens. In the description, and M. atlanticus (Costa et al. 2016). Field work counts of vertebrae and pleural ribs were taken conducted over the last 15 years has greatly in- from cleared and stained (c&s) specimens, pre- creased the number of known species in pared according to Taylor & Van Dyke (1985). Melanorivulus, as well as revealing a broader geo- Frontal squamation follows Hoedeman (1958) and graphical distribution for the genus (Nielsen et al. Costa (2006b). For vertebral counts, the caudal 2016; Costa et al. 2016). In fact, up to 1989, only compounded centrum was counted as a single ele- two species currently assigned to the genus ment. Osteological features included in the de- Melanorivulus were known: M. punctatus scription are those considered phylogenetically in- (Boulenger 1895), from the Rio Paraguai basin, formative in recent studies of the species assigned and M. zygonectes (Myers 1927) from the Rio To- to the genus Melanorivulus (Costa 2006, 2011, cantins basin. After 1994, field studies were inten- 2016). Institutional abbreviations follow Sabaj sified and many new species were discovered and Pérez (2014). Comparisons with congeners were described (e.g., Nielsen & Pinto 2015; Costa et al. based primarily on the literature (Costa 2003, 2016). Most Melanorivulus species inhabit areas of 2005, 2007, 2008, 2009, 2016). springs, locally known as “veredas”, which are flooded areas with shallow water, where a vegeta- aqua vol. 23 no. 2 - 28 April 2017 56 Dalton Tavares Bressane Nielsen Melanorivulus canesi, n. sp. body never green metallic and narrow red parallel (Figs 1-2; Table I) stripes), caudal fin with 3-5 red vertical bars, with a red distal margin (vs. 1-2 almost imperceptible Holotype: MZUSP 121647, male, 22.3 mm SL: vertical red bars in M. modestus or five black nar- Brazil, Pará, Novo Progresso, “Vereda” at Km 84, row bars in M. karaja or else red bars absent). Fe- road BR-163, near to CPBV-FAB, Rio Curuá males of M. canesi can be distinguished from all basin, 8°53’18”S 54°59’00”W; O. T. Oyakawa, W. other species belonging to the Melanorivulus zy- M. Ohara & M. N. Pastana, 11 June 2015 gonectes species group by presenting a false dark Paratypes: MZUSP 121670, 4 males 16.1-20.1 ocellus at caudal fin, followed by conspicuous dark mm SL, 6 females 17.6-18.1 mm SL, 4 c&s, 17.8- vertical bars on the basal portion of the upper lobe 20.1 mm SL: same data as holotype. of caudal fin (vs. a distinct color pattern), presence Diagnosis: Males of Melanorivulus canesi can be of a row scales at dorsal-fin basis (vs. absence of distinguished from males of all other species of the scales at dorsal-fin basis), and lack of red spots or Melanorivulus zygonectes species group by its red lines below midline (vs. presence in another unique color pattern, presenting sides of body species). Additionally, the species can be distin- metallic green, with 11-12 oblique brown bars, and guished from congeners by presenting few pelvic within these bars, one or two narrow red oblique fin rays (5 vs. 6 in M. modestus, 6-7 in M. kayabi or lines are present, sometimes connected (vs. sides of 7 in the remaining species), dorsal-fin origin at ver-

Fig. 1. Melanorivulus canesi, MZUSP 121647, holotype, male, 22.3 mm SL, in life. Photo by W. M. Ohara.

Fig. 2. Melanorivulus canesi, MZUSP 121670, paratype, female, 18.0 mm SL, in life. Photo by W. M. Ohara.

57 aqua vol. 23 no. 2 - 28 April 2017 Description of two new species of the Melanorivulus zygonectes species group from Rio Xingu and Rio Tapajós basins, Brazil

Table I. Morphometric and meristic data for the holotype (H) and paratypes of Melanorivulus canesi n.sp.

H Paratypes Male Males n = 4 Females n = 6

Standard length (mm) 22.3 16.1-20.1 17.6-18.1

Percents of SL Body depth 21.4 20.5-24.9 18.8-25.0 Caudal peduncle depth 15.2 12.3-15.0 12.1-14.2 Pre-dorsal length 74.7 72.2-76.1 73.9-78.9 Pre-pelvic length 52.4 53.4-56.1 50.0-56.8 Length of dorsal-fin base 14.2 12.2-14.0 11.6-15.9 Length of anal-fin base 22.8 19.6-22.4 18.8-22.1 Caudal-fin length 27.6 26.4-33.7 30.3-34.0 Pectoral-fin length 19.0 18.6-20.5 16.5-19.8 Pelvic-fin length 10.0 8.2-9.9 10.3-11.3 Head length 28.5 27.3-30.6 25.7-30.2

Percents of HL Head depth 61.6 57.7-64.0 60.0-63.6 Head width 75.0 65.3-70.3 70.0-72.9 Snout length 13.0 12.7-14.1 12.6-13.9 Lower jaw length 20.1 20.2-22.6 16.7-18.0 Eye diameter 35.0 35.1-40.0 35.5-41.8

Counts Dorsal fin 10 10 10 Caudal fin 30 29-31 29-31 Anal fin 14 14 14 Pelvic fin 5 5 5 Pectoral fin 11 10 10 tical through the base of 7th anal-fin ray (vs. 13th- fin and pelvic-fin bases. Dorsal-fin origin at verti- 16th in M. wallacei or 8th-10th in the remaining cal through the base of the 7th anal-fin ray, between species). neural spines of vertebrae 19-20; anal-fin origin Description: Morphometric data are presented in between pleural ribs of vertebrae 15-16; dorsal-fin Table I. Largest male 22.3 mm SL, largest female rays 10; anal-fin rays 13-14; caudal-fin rays 29-31; 18.1 mm SL. Body slender, cylindrical and com- pectoral-fin rays 10-11; pelvic-fin rays 5. pressed, greatest body depth at level of pelvic-fin Scales small, cycloid; body and head entirely base. Dorsal profile weakly convex from snout to scaled, except on the ventral surface of head; scales the first dorsal-fin ray, concave from last dorsal-fin present on dorsal fin bases in females, body squa- ray to the end of the caudal fin peduncle; ventral mation extending over anterior 15-20% of caudal profile slightly convex from lower jaw to anal fin fin. Frontal squamation F-patterned; E-scales not terminus, slightly concave along caudal peduncle. overlapping. Longitudinal series of scales 33-34; Snout short, rounded. Jaws short. Dorsal-fin transverse series of scales 8; scale rows around cau- rounded, anal-fin rounded, without filaments in dal peduncle 16; no contact organs on scales and both sexes; caudal-fin rounded; pectoral-fin round- fin rays. ed; pelvic fin short, elliptical; tip of pelvic fin Cephalic neuromasts: supraorbital 3+3, parietal reaching anus or 1st anal-fin ray in males, and 1, anterior rostral 1, posterior rostral 1, infraorbital slightly anterior to anus in females. Pelvic-fin bases 1+10-11+1, preorbital 2, otic 2, post-otic close to each other, almost joined. Pectoral-fin 1,supratemporal 1, median opercular 1, ventral op- rounded, with its posterior margin reaching verti- ercular 2, preopercular 2+4, mandibular 3+1, later- cal at about 80-85 % of length between pectoral- al mandibular 1, paramandibular 1; two neuro- aqua vol. 23 no. 2 - 28 April 2017 58 Dalton Tavares Bressane Nielsen masts on caudal-fin base. Six branchiostegal rays. green metallic and narrow red parallel stripes). Up- Total number of vertebrae 28-29. per caudal-fin base metallic green, lower part light Coloration: Males. Sides of body metallic red, almost pink. Dorsum olive-brown; venter green, with 11-12 oblique brown bars, within these white; sides of head metallic green, with large post- bars, one or two narrow red oblique lines are pre- orbital dark blotches; upper jaw dark, lower jaw sent, sometimes connected (vs. sides of body never dark gray to black; iris pale yellow. Dorsal fin

Fig. 3. Type locality of Melanorivulus canesi, strem tributary of rio Curuá, rio Xingu basin, Pará state Brasil. Photo by W. M. Ohara.

59 aqua vol. 23 no. 2 - 28 April 2017 Description of two new species of the Melanorivulus zygonectes species group from Rio Xingu and Rio Tapajós basins, Brazil metallic green, with 2-3 red transversal bars; anal white (vs. light yellow in M. kayabi, light blue in fin with basal portion whitish blue, mid-portion M. salmonicaudus and M. rubromarginatus, light light red , distal portion metallic green with nar- yellow in M. crixas, M. javahe, M. karaja, M. spixi, row pale red margin. Caudal fin metallic green M. petrisecundi, M. wallacei, M. kayabi, and M. with 3-5 red vertical bars, distal margin red. Pec- parnaibensis, orange in M. imperatrizensis, and pale toral and pelvic fins hyaline. orange in M. megaroni), lower predorsal length, Females: Sides of body pale green, with 8 narrow 72.1-72.9% SL (vs. 73.9-78.1% SL in M. kayabi oblique red lines, dark midlateral stripe extending and 76.9-80.5% SL in M. megaroni), lower anal- from opercular region to vertical line through dor- fin base length, 16.2-17.5% SL (vs. 18.4-22.7% sal fin. Abdominal region white. Dorsum olive- SL in M. rubromarginatus and 21.3-24.7% SL in brown, with irregular small dark lines and mark- M. salmonicaudus), and caudal fin spatulated (vs. ings. Sides of head whitish with irregular dark subtruncated in M. javahe or oval-shaped in other blotches, upper jaw brown, lower jaw dark brown; species), and additionally, with the exception of iris reddish. Dorsal fin hyaline, base with brown Melanorivulus kayabi, by presenting sides of body scales, posterior margin with 2-3 black irregular light brownish gray, with 10-13 narrow, oblique blotches; anal fin mostly hyaline, light yellow at red bars forming an “X” design below lateral mid- medial portion, distal margin black. Caudal fin line (vs. chevron-like pattern, when present, with hyaline with four black bars; two anteriormost bars vertex at the lateral midline). Females of more conspicuous, on dorsal portion of caudal-fin Melanorivulus britzkei differ from other species be- basis. Pectoral and pelvic fins hyaline. longing to the Melanorivulus zygonectes species Ecological notes: The type-locality of Mela no ri - group by presenting caudal fin with bright yellow vulus canesi was a flowing, shallow (depth 0.5-1.5 at the upper and lower portion of the fin (paler at m), narrow (2 meter wide), clear water stream, middle fin rays), with 3 thick black vertical bars, with grasses on the banks, and bottom composed and distal margin of the fin with a thick black con- by sand and mud (Fig. 3). tour (vs. caudal-fin pale yellow with 3-6 narrow Distribution: Only known from the type locality, gray bars and narrow black contour in M. kayabi a tributary of the rio Curuá, middle rio Xingu and M. javahe, light orange, with four reddish basin, Pará state, Brazil. brown vertical bars, upper and dorsal fin margins Etymology: Named in honor of the late aquari- light black in M. imperatrizensis, a dark gray retic- um hobbyist and environmentalist Paulo José Fer- ulate pattern in M. petrisecundi, dorsal portion of reira Canes. caudal fin light yellow with 5-6 narrow gray bars in M. spixi, 5-8 narrow sinuous gray bars in M. wal- lacei, pale yellow with 3-6 narrow gray bars, often Melanorivulus britzkei, n. sp. interrupted forming isolated spots in M. megaroni, (Figs 4-5; Table II) and light gray with 3-4 dark gray bars in M. rubro- marginatus), tip of pelvic-fin rays dark (vs. hyaline, Holotype: MZUSP 121646, male, 31.0 mm SL: orange or yellow in other species). Additionally, M. Brazil, Pará state, Novo Progresso, rio São Bento, britzkei can be distinguished from the remaining headwaters of rio Braço Norte, 9°12’35”S species belonging to the Melanorivulus zygonectes 54°52’7”W; O. T. Oyakawa, W. M. Ohara & M. species group, except M. kayabi and M. modestus, N. Pastana, 12 June 2015. by presenting fewer pelvic-fin rays (6 vs. 7), and Paratypes: MZUSP 121669, 8 males 24.2-29.0 fewer pectoral-fin rays, except M. salmonicaudus mm SL, 8 females 26.1-34.0 mm SL (6 c&s, 27.4- and M. zygonectes (10-11 vs. 13-14). 36.1 mm SL): same data as holotype. Description: Morphometric data presented in Diagnosis: Males of Melanorivulus britzkei is dis- Table II. Largest male examined 31.0 mm SL, tinguished from all other species of the Melano - largest female 34.0 mm SL. Dorsal profile weakly rivulus zygonectes species group by presenting sides convex from snout to end of dorsal-fin base, ap- of head metallic yellow (vs. light brownish gray M. proximately straight on caudal peduncle; ventral kayabi, M. spixi, M. salmonicaudus, M. karaja, M. profile gently convex from lower jaw to anal-fin zygonectes, M. wallacei and M. megaroni, pale origin, approximately straight along caudal pedun- brown in M. parnaibensis and M. petrisencundi, cle; body slender, approximately cylindrical anteri- metallic blue in M. imperatrizensis), pelvic fin orly, becoming gradually compressed towards cau- aqua vol. 23 no. 2 - 28 April 2017 60 Dalton Tavares Bressane Nielsen dal fin. Greatest body depth at level of pelvic-fin anal fin bases, body squamation extending over an- base; snout short, rounded. Dorsal-fin slight point- terior 10-15% of caudal fin; frontal squamation F- ed, anal fin slightly pointed, without filaments in patterned; E-scales not overlapping; Longitudinal both sexes; caudal fin spatulated; pectoral-fin series of scales 32-33; transverse series of scales 8; rounded; pelvic-fin short, elliptical; tip of pelvic- scales rows around caudal peduncle 16; no contact fin reaching first ray of anal fin in males and be- organs on scales and fin rays. tween the urogenital papilla and the anus in fe- Cephalic neuromasts: supraorbital 3+3, parietal males; pelvic-fin bases close to each other, almost 1, anterior rostral 1, posterior rostral 1, infraorbital joined. Pectoral-fin rounded, with posterior mar- 1+10-12+1, preorbital 2, otic 1, post-otic 1, gin reaching vertical at about 80-85% of length be- supratemporal 1, median opercular 1, ventral oper- tween pectoral fin and pelvic fin. Dorsal-fin origin cular 1, preopercular 2+4, mandibular 3+1, lateral between at vertical through the base of the 7th-8th mandibular 2, paramandibular 1; one neuromast anal-fin rays, neural spines of vertebrae 20; anal-fin on each scale of lateral line; two neuromasts on origin between pleural ribs of vertebrae 15-16; caudal-fin base. Six branchiostegal rays. Total num- dorsal-fin rays 8-10; anal-fin rays 12-13; caudal-fin ber of vertebrae 29-30. rays 29-30; pectoral-fin rays 10-11; pelvic-fin Coloration: Males. Sides of body light rays 5. brownish gray, with narrow 10-13 oblique red bars Scales large, cycloid, no scales on dorsal fin and forming an “X” design below lateral midline. Dor-

Fig. 4. Melanorivulus britzkei, MZUSP 121646, holotype, male, 31.0 mm SL, in life (photo reversed). Photo by W. M. Ohara.

Fig. 5. Melanorivulus britzkei, MZUSP 121669, paratype, female, 29.4 mm SL, in life (photo reversed). Photo by W. M. Ohara.

61 aqua vol. 23 no. 2 - 28 April 2017 Description of two new species of the Melanorivulus zygonectes species group from Rio Xingu and Rio Tapajós basins, Brazil

Table II. Morphometric and meristic data for the holotype (H) and paratypes of Melanorivulus britzkei sp. n.

H Paratypes Male Males n = 8 Females n = 8

Standard length (mm) 31.0 29.0-24.2 34.0-26.1

Percents of SL Body depth 20.5 18.6-20.2 18.3-21.7 Caudal peduncle depth 12.9 9.9-13.7 10.8-13.1 Pre-dorsal length 72.1 72.4-72.9 75.0-77.9 Pre-pelvic length 52.2 54.4-56.0 50.7-59.7 Length of dorsal-fin base 15.8 11.4-45.2 8.8-13.0 Length of anal-fin base 17.3 16.2-17.5 13.7-22.0 Caudal-fin length 28.0 23.4-26.8 19.2-27.5 Pectoral-fin length 19.6 16.4-20.2 17.9-21.4 Pelvic-fin length 14.1 10.7-12.9 9.3-11.7 Head length 27.3 26.0-30.5 22.6-29.6

Percents of HL Head depth 60.7 56.2-61.9 52.8-63.7 Head width 66.2 60.0-74.6 63.6-74.2 Snout length 13.9 13.1-14.2 12.9-14.1 Lower jaw length 20.1 19.3-21.2 18.7-20.1 Eye diameter 31.2 28.2-33.6 27.4-32.8

Counts Dorsal fin 10 8-10 9 Caudal fin 29 29-30 29-30 Anal fin 13 13 13 Pelvic fin 6 6 6 Pectoral fin 11 10-11 10-11 sum light brownish gray; abdominal region with numerous small black dots; abdominal region whitish; sides of head metallic yellow, with black whitish; upper jaw brown, lower jaw dark grey; iris bar beginning anterior to the eye and extending brown. Dorsal-fin light yellow, with an irregular posteriorly to area immediately above pectoral-fin basal black stripe, and distal portion with large insertion; upper jaw brown, lower jaw dark gray to black band. Anal fin whitish, its distal portion with black; iris pale orange. Dorsal fin orange, with large black band. Caudal fin bright yellow at the small red spots; anal fin with basal portion light upper and lower portion of the fin (paler at middle metallic blue, medial portion light blue and light fin rays), with 3 thick black vertical bars, and distal yellow with red dots, and with distal portion pre- margin of the fin with a thick black contour, one senting a black line; central portion of caudal fin large black spot on dorsal portion of fin base. Pec- orange, dorsal and ventral portions yellow; pectoral toral and pelvic fins hyaline. fin hyaline; pelvic fin white. Ecological notes: The type locality was small (2 X Females. Sides of body light brown, with 8-9 nar- 1 meters), shallow (20-40 cm) pool, within an al- row oblique red bars formed by interspaced dots, most dry stream, with sandy bottom and herba- bars often forming chevron-like pattern pointing ceous marginal vegetation (Fig. 6). forward, vertices along lateral midline; longitudi- Distribution: Known only from the type locality, nal black bar beginning slightly behind eye and ex- a headwater tributary of rio Braço Norte, itself a tending to vertical through anal-fin terminus, be- tributary of rio Teles Pires, rio Tapajós basin, Pará coming gradually fainter from vertical through state, Brazil. pelvic-fin insertion onwards. Sides of head brown, Etymology: The specific name honors the ichthy- with an irregular black stripe. Dorsum light brown, ologist Ricardo Britzke. aqua vol. 23 no. 2 - 28 April 2017 62 Dalton Tavares Bressane Nielsen

DISCUSSION javahe, M. kayabi, M. karaja, M. modestus, M. Both new species described in the present paper megaroni, M. parnaibensis, M. petrisecundi, M. belong to Melanorivulus zygonectes species group, rubromarginatus, M. rubroreticulatus, M. salmoni- which is diagnosed by two synapomorphies: pres- caudus, M. spixi, M. wallacei, and M. zygonectes. ence of red chevron-like marks on the posterior Melanorivulus canesi has a distinctive pattern of portion of the flank, with apices closer to the ven- chevron-like markings when compared to the oth- tral surface of body and presence of a distinctive er species of the M. zygonectes species group. In this light stripes on the dorsal and ventral margins of species, the chevron-like markings run as parallel the caudal fin (Costa 2008, 2009, 2016).The lines above the midline, forming below the midline Melanorivulus zygonectes species group includes the a marking as an “X”. This pattern is certainly de- following species: M. crixas, M. imperatrizensis, M. rived from the most usual chevron-like pattern.

Fig. 6. Type locality of Melanorivulus britzkei, a tributary of rio São Bento, rio Tapajós basin, Pará, Brazil. Photo by W. M. Ohara.

63 aqua vol. 23 no. 2 - 28 April 2017 Description of two new species of the Melanorivulus zygonectes species group from Rio Xingu and Rio Tapajós basins, Brazil

Fig. 7. Map of the rio Xingu and rio Tapajós basins in Brazil showing the distribution of Melanorivulus canesi (circle) and Melanorivulus britzkei (star). aqua vol. 23 no. 2 - 28 April 2017 64 Dalton Tavares Bressane Nielsen

The presence of dark gray bars along the flanks is gion between the Amazon and Cerrado domains. another color pattern feature of the M. zygonectes Melanorivulus canesi is found in the Serra do species group present in M. canesi, but in the latter Cachimbo, a low hill range that marks the border species the dark gray stripe are alternated by metal- between the middle Rio Xingu basins and the Rio lic green pigmentation. Teles Pires, the main tributary of the Rio Tapajós. Although Costa (2016) has defined that the red The rivers that originates in the eastern versant of marks present in the species of the Melanorivulus the Serra do Cachimbo flow toward the Rio Xingu zygonectes species group are formed by dots and basin, whereas the rivers originating at the western spots, in M. canesi and M. britzkei, and in some versant flow toward the Rio Teles Pires basin. specimens of M. kayabi, M. rubroreticulatus, and M. javahe, these red marks are formed by lines. The typical “X” marking pattern below the mid- Key to species of the Melanorivulus zygonectes line is also present in M. britzkei, but in the latter species group (adapted from Costa 2016), species there are no parallel lines, as in M. canesi, including M. canesi, M. britzkei, and the “X” marking pattern originates from non- and M. imperatrizensis parallel lines. Melanorivulus britzkei appears to be related to M. kayabi, but in the latter species there 1- Body sides, in males, with narrow, continuous is no formation of the “X” marking pattern below oblique red bars forming chevron-like marks; the midline, but rather, the chevron-like pattern is caudal fin, in females, with distinctive white present. Additionally, males of Melanorivulus area above caudal spot, posteriorly extending as britzkei differs from males of M. kayabi by pre- series of small white spots; usually 5 or 6 senting a black line at the distal portion of the anal pelvic-fin rays, 7th ray rudimentary .….…....2 fin (vs. absent), caudal fin central portion orange, Body sides, in males, with oblique rows of red with dorsal and ventral portions yellow (vs. cau- dots, sometimes in contact to short oblique dal-fin pale yellow dorsally, white or pale yellow bars on dorsal portion of flank and caudal pe- ventrally), pelvic fin white (vs. pelvic-fin light yel- duncle area, caudal fin in females without dis- low), lower caudal-fin length 23.4-28.0% SL (vs. tinctive white area above caudal spot, always 7 34.1-40.5% SL), lower head with length 60.0- pelvic-fin rays ….….….….….….….….…. 3 74.2% HD (vs. 74.0-85.0% HD), and fewer pec- 2- Body sides, in males, with red marks along its toral-fin rays 10-11(vs. 13). Melanorivulus britzkei entire extension; middle portion of caudal fin, females differs from M. kayabi females by present- in females, with dark grey to black bars; 28-31 ing a lower caudal-fin length (19.2-27.5% SL, vs. caudal-fin rays ….….…. Melanorivulus kayabi 33.5-40.7%). Body sides, in males, with rudimentary red The majority of the species belonging to the marks; middle portion of caudal fin, in fe- Melanorivulus zygonectes species group inhabit the males, with dark grey to black irregular marks; Araguaia- system; this may be in 31-33 caudal-fin rays ….….….….….…..….. part related to the more intense fieldwork conduct- ….….….….….….… Melanorivulus modestus ed in this area when compared to the Xingu and Body sides, in males, light brownish gray, with Tapajós rivers basins. Out of the 17 species de- narrow 10-13 oblique red bars forming an “X” scribed for the group, 9 occur at the Araguaia-To- pattern below lateral midline; in females, cau- cantins river system, 7 ar the rio Xingu and rio dal fin with bright yellow background, more Tapajós rivers systems, and a single species occur at intense in the upper and lower regions and the Rio Parnaíba basin. The phylogenetic analysis paler at the central region, with 3 thick black and biogegraphical study presented by Costa vertical bars, distal margin with a thick black (2016) suggests that the Melanorivulus zygonectes band ….….….….….... Melanorivulus britzkei species group has its origin at the Araguaia-Tocan- Body sides, in males, metallic green, with 11- tins river system and later dispersed to other rivers 12 oblique brown bars, bars with one or two basins. narrow red oblique lines, when two narrow red Melanorivulus britzkei is found at a tributary of oblique lines present, parallel and connected by the rio Teles Pires within the Amazon domain, 1-3 narrow red lines; in females, presence of a whereas its purported closer relative, M. kayabi, is black spot at upper portion of caudal fin…… found at the rio Teles Pires basin at the ecotonal re- …………...... …...... ….. Melanorivulus canesi

65 aqua vol. 23 no. 2 - 28 April 2017 Description of two new species of the Melanorivulus zygonectes species group from Rio Xingu and Rio Tapajós basins, Brazil

3- Red marks interrupted along body midline; in narrow red bars on basal portion; pre-dorsal males, lower jaw without red pigmentation… length, in males, 76.9-80.5% SL…………… …………………………………………… 4 …….….….….….….. Melanorivulus megaroni Red marks not interrupted along body mid- 8- Body sides, in males, with minute red dots, di- line; in males, tip of lower jaw with red pig- ameter of larger dots about as wide as pupil di- mentation ………………………………… 5 ameter or slightly less ………...…………… 9 4- Caudal fin, in males, pale blue, with broad red Body sides, in males, with small red spots, di- bars, often connected to reticulate pattern; anal ameter of larger spots about half pupil diameter fin, in males, with intense bright blue color on or slightly more …………………………. 10 basal portion, contrasting with red marks; mid- 9- Caudal fin, in males, light bluish with dark dle portion of caudal fin in females not reticu- grey bars; caudal fin, in females, with round late, frontal squamation F-patterned ……… basal spot, its diameter equal to or greater than ………………. Melanorivulus rubroreticulatus eye diameter ……….….….…….….….….… Caudal fin, in males, orange, without bars; anal ....…….….….….….…. Melanorivulus karaja fin, in males, never with intense bright blue Caudal fin, in males, hyaline with small dark color on basal portion; in females, middle por- pink spots; caudal fin, in females, with basal tion of caudal fin reticulated, frontal squama- spot subtriangular, smaller than eye………… tion E-patterned………….….….….….….... ………...... …... Melanorivulus zygonectes ….….….….….….. Melanorivulus petrisecundi 10- Body sides, in males, with red spots irregularly In males, all fins orange, with small and few arranged ………………...…...….….….... 11 oblique red spots only on the posterior portion Body sides, in males, with red spots arranged of body; small, few reddish-brown spots at cau- forming oblique rows ……….….….…..…12 dal fin, red spots not arranged as chevrons, 11- Caudal fin, in males, with transverse rows of black pigmentation absent on the head, fe- small red spots over whole fin except marginal males with 3-4 reddish-brown bars at the cau- areas; caudal fin, in females, with 3-5 dark grey dal-fin………… Melanorivulus imperatrizensis to black bars; pelvic fin, in males, not surpass- 5- Caudal fin, in males, with dense orangish pink ing urogenital papilla posteriorly; pelvic fin, in pigmentation along the whole fin …………. 6 males reaching between base of 1st and 3rd Caudal fin, in males never with dense orangish anal-fin ray, its length 13.1-15.1% SL ……… pink pigmentation along the whole fin ….… 8 ………….…....… Melanorivulus parnaibensis 6- Body sides, in females, with red dots well sepa- Caudal fin, in males, with transverse rows of rated by interspace; caudal fin, in females, small spots over whole fin, sometimes minute reticulated, at least on its dorsal and posterior red dots restricted to basal portion of fin; cau- portions, and with a reddish grey basal spot; dal fin, in females, with 5-8 dark grey to black body depth 22.1-24.9% SL in females; caudal- bars at base of 1st and 3rd anal-fin rays; pelvic fin length 23.6-25.2% SL in females; caudal- fin, in males, not surpassing urogenital papilla fin length, in males, 32.3-37.7% SL; 10-11+1 posteriorly, its length 10.4-13.0% SL ……… neuromasts around orbit …….….….…...… ………….….….….… Melanorivulus wallacei …...... Melanorivulus spixi 12- Caudal fin, in males, subtruncate, with faint Body sides, in females, with red dots united, reddish orange pigmentation on ventral mar- forming oblique bars; caudal fin, in females, gin, and dark red bars on middle portion; in never reticulated and with black basal spot, males, dark red bars extending over most dorsal without red pigmentation; body depth 20.0- fin …………………… Melanorivulus javahe 22.2% SL in males, 20.2-22.3% SL in females; Caudal fin, in males, oval, with distinctive red- caudal-fin length, in males, 37.3-42.3% SL; dish orange to intense red pigmentation on 12-14+1 neuromasts around orbit ……..….. 7 ventral margin, and without red marks on mid- 7- Distal margin of anal fin, in males, without dle portion; in males, dark red bars restricted to black marks; caudal fin, in males without red distal portion of dorsal fin …...... 13 bars; pre-dorsal length, in males, 73.9-76.2% 13- In males, distal margin of dorsal and anal fin, SL …...... Melanorivulus salmonicaudus dorsal margin of caudal fin, and anterior mar- Distal margin of anal fin, in males, with a nar- gin of pelvic fin without orangish red pigmen- row black margin; caudal fin, in males, with tation; in males, reddish orange stripe on ven- aqua vol. 23 no. 2 - 28 April 2017 66 Dalton Tavares Bressane Nielsen

tral margin of caudal fin abruptly narrowing COSTA, W. J. E. M. 2009. Rivulus megaroni, a new killifish posteriorly, not reaching posterior portion of from the Xingu River drainage, southern Brazilian Ama- fin ….….….….….….…. Melanorivulus crixas zon (Cyprinodontiformes: ). Ichthyological Ex- In males, distal margin of dorsal and anal fin, ploration of Freshwaters 20: 365-370. COSTA, W. J. E. M. 2011. Phylogenetic position and taxo- dorsal and ventral margins of caudal fin, and nomic status of , , Cyn- anterior margin of pelvic fin with orangish red odonichthys, and Melanorivulus (Cyprin- stripe, caudal fin stripes not narrowing posteri- odontiformes: Rivulidae). Ichthyological Exploration of orly, reaching posterior portion of fin ……… Freshwaters 22: 233-249 ……………… Melanorivulus rubromarginatus COSTA, W. J. E. M. 2016. Comparative morphology, phy- logenetic relationships, and taxonomic revision of South ACKNOWLEDGEMENTS Americam killifishes of the Melanorivulus zygonectes The author is very indebted to Osvaldo T. Oy- species group (Cyprinodontiformes: Rivulidae). Ichthy- ological Exploration of Freshwaters 27: 107-152. akawa, Willian M. Ohara and Murilo N. Pastana COSTA, W. J. E. M., AMORIM, P. F. & BRAGANÇA, P. H. N. (MZUSP) for collecting and loaning the material 2015. A new miniature killifish of the genus Melanorivulus studied in the present contribution. Willian M. (Cyprinodontiformes: Rivulidae) from the coastal plains of Ohara provided the pictures and prepared the map. north-eastern Brazil. Vertebrate Zoology 65: 31-35. Thanks are also due to Itamar A. Martins from COSTA, W. J. E. M., AMORIM, P. F. & RIZZIERI, R. C. 2016. Universidade de Taubaté (UNITAU), for provid- Molecular phylogeny and biogeography of the South ing lab facilities. Dan Katz and Priscila G. C. de American savanna killifish genus Melanorivulus (Teleostei: Moraes read the manuscript and corrected lan- Aplocheilidae). Vertebrate Zoology 66: 267-273. COSTA, W. J. E. M. & DE LUCA, A. C. 2011. Rivulus guage style. Flávio C.T. Lima (ZUEC) reviewed schunki, a new species of the killifish subgenus the manuscript and offered useful suggestions. Melanorivulus, from eastern Brazilian Amazon (Cyprin- odontiformes: Rivulidae). Ichthyological Exploration of REFERENCES Freshwaters 21: 289-293. COSTA, W. J. E. M. 1995. Pearl killifishes: The Cynolebiati- NIELSEN, D. T. B. & PINTO, C. S. 2015. Melanorivulus im- nae. Systematics and Biogeography of a Neotropical annual peratrizensis, a new species of killifish (Cyprinodontif- subfamily (Cyprinodontiformes: Rivulidae). TFH Pub- ormes: Rivulidae) from the rio Tocantins basin, Brazil. lications, Neptune City, 128 pp. aqua International Journal of Ichthyology 21 (3): 136-143. COSTA, W. J. E. M. 2003. A new species of the genus Rivu- NIELSEN, D. T. B., NEVES, P. A. B. A. & YWAMOTO, E. V. lus Poey, 1860 from the Parnaiba river basin, northeast- 2016. Melanorivulus polychromus, a new species of killi- ern Brazil (Teleostei, Cyprinodontiformes, Rivulidae). fish from the rio São José dos Dourados drainage, middle Boletim do Museu Nacional 511: 1-7. rio Paraná basin, southwestern Brazil, with a redescrip- COSTA, W. J. E. M. 2005. Seven new specie of the killifish tion of Melanorivulus apiamici (Cyprinodontiformes: genus Rivulus (Cyprinodontiformes, Rivulidae), from the Rivulidae). aqua International Journal of Ichthyology 22 Paraná, Paraguay and upper Araguaia river basins, central (2): 79-88. Brazil. Neotropical Ichthyology 3: 69-82. HOEDEMAN, J. J. 1958. The frontal scalation pattern in COSTA, W. J. E. 2006. Descriptive morphology and phylo- some groups of tooth carps. Bulletin of Aquatic Biology 1: genetic relationship among species of the Neotropical an- 23-28. nual killifish genera Nematolebias and Simpsonichthys SABAJ PÉREZ, M. H. (ed.) 2014. Standard symbolic codes for (Cyprinodontiformes: Aplocheiloidei: Rivulidae). Neo - institutional resource collections in herpetology and ichthyol- tro pical Ichthyology 4: 1-26. ogy. Version 5.0 (22 September 2014). Electronically ac- COSTA, W. J. E. M. 2007. Five new species of the cessible at http://www.asih.org/, American Society of aplocheiloid killifish genus Rivulus, subgenus Mela no - Ichthyologists and Herpetologists, Washington D.C. rivulus, from the middle Araguaia river basin, central TAYLOR, W. R. & VAN DYKE, G. C. 1985. Revised proce- Brazil (Teleostei: Cyprinodontiformes: Rivulidae). aqua, dures for staining and clearing small and other ver- International Journal of Ichthyology 13 (2): 55-68. tebrates for bone and cartilage study. Cybium 9: 107-119. COSTA, W. J. E. M. 2008. Rivulus kayabi, a new killifish VALDESALICI, S., GIL, J. R. G. & NIELSEN, D. T. B. 2011. from the Tapajós river basin, southern Brazilian Amazon Rivulus albae, a new species of killifish (Teleostei: Cyprin- (Cyprinodontiformes: Rivulidae). Ichthyological Explo- odontiformes: Rivulidae) from northeastern Brazil. Verte- ration of Freshwaters 18: 345-350. brate Zoology 61: 105-108.

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