A new colorful species of Geophagus ( Teleostei : Cichlidae ) , endemic to the rio Aripuanã in the Amazon basin of Brazil

Geophagus mirabilis, new species, is endemic to the rio Aripuanã drainage upstream from Dardanelos/Andorinhas falls. The new species is distinguished from all other species of the genus by the presence of one to five large black spots arranged longitudinally along the middle of the flank, in addition to the black midlateral spot that is characteristic of species in the genus and by a pattern of iridescent spots and lines on the head in living specimens. It is further distinguished from all congeneric species, except G. camopiensis and G. crocatus, by the presence of seven (vs. eight or more) scale rows in the circumpeduncular series below the lateral line (7 in G. crocatus; 7-9 in G. camopiensis). Including the new species, five cichlids and 11 fish species in total are known only from the upper rio Aripuanã, and 15 fish species in total are known only from the rio Aripuanã drainage.


Introduction
The South American cichlid genus Geophagus Heckel is distinguished by the presence of prolongations of the swim bladder into the caudal region that reach past the vertical through the base of the last anal-fin ray, accompanied by a series of supporting caudal ribs (Kullander, 1998).The genus comprises 19 valid species distributed throughout the Amazon and Orinoco river basins, coastal rivers of the Guianas, and some coastal basins in the Brazilian states of Pará, Maranhão, and Piauí (Kullander, 2003;Stawikowski & Werner, 2004).Kullander (1995: 158) reported an undescribed species of Geophagus from the rio Aripuanã drainage upstream from Dardanelos/Andorinhas falls.The rio Aripuanã is a major right bank tributary of the lower rio Madeira, and the Dardanelos falls mark its entry into the Madeira floodplain.
Although it has been little explored, many works recorded species of fishes in the upper rio Aripuanã (e.g., Kullander, 1990Kullander, , 1995;;Rocha et al., 2008aRocha et al., , 2008b)), and the fish fauna is distinct from that from the rio Madeira proper and the floodplain portion of the rio Aripuanã, as reported by Rapp Py- Daniel et al. (2007).The Geophagus from the rio Aripuanã was exported for the ornamental fish market in 2011 and has been cultivated in aquaria in Europe and North America (Gottwald, 2011).Specimens available to Kullander (1995) had been collected as early as 1975 and were not well preserved, thereby delaying the species' description.However, recent material collected in 2004, 2005 and 2013, including live color images, permitted a formal description of the species, which is provided herein.

Material and Methods
Measurements were taken with digital calipers to the nearest 0.1 mm.Counts of scales, fin rays and gill rakers were made under a stereomicroscope.Measurement procedures and counts follow Kullander (1986) and Kullander & Nijssen (1989).Meristic data marked by an asterisk are the values for the holotype.Numbers in parenthesis after a count value represent the frequency of occurrence in the sample.Osteological characters were examined in one specimen (NUP 15117, 85.5 mm SL) cleared and stained (c&s) using the protocol by Taylor & Van Dyke (1985), supplemented by vertebral counts from nine X-radiographed specimens (INPA 1364).Measurements of the lower pharyngeal jaw follow Barel et al. (1977).The term midlateral spot is used herein according to nomenclature established in early papers (e.g., López-Fernández & Taphorn, 2004), meaning a black marking situated approximately on the middle of the flank and present in all species of Geophagus, with the exception of individuals of G. altifrons Heckel, which has been observed first by Heckel (1840) in its original description.
Pelvic fin naked, except for base of rays, covered by just one scale.Pectoral fin usually completely naked, rarely with few scales on rays near base.Dorsal fin with scale rows on inter-radial membranes, usually between median spines and median soft rays (in one large specimen, from membrane posterior to third spine almost to last inter-radial membrane); scale rows obliquely oriented, not parallel to rays; usually one, up to three scale rows per membrane, separated by naked space; up to six scales per row; scaly pad absent at base of dorsal fin.Anal fin naked in all except two specimens (scales between all soft rays, only one row per membrane, up to two scales per row).Caudal fin covered with scales stochastically distributed from base of rays to one-fifth of their length; from this point, scales ordered in non-imbricated series, one per inter-radial membrane (including membranes between branches of some rays); median series with about five scales, outer series with much more scales (reaching approximately 30 in series comprising lower lateral line branch), leaving middle of fin (between D3 and V3) basically naked and dorsal and ventral parts covered almost until posterior margin; dorsal lateral line branch between rays D3 and D4; ventral branch between rays V4 and V5, longer than dorsal branch.
Pharyngobranchial 2 with thick ventral portion, bearing about six rows of slender teeth, up to two retrorse cusps each.Pharyngobranchial 3 with nine rows of teeth (medialmost row with large, cylindrical teeth with up to four cusps; laterally, teeth progressively compressed, decreasing in size; lateralmost teeth with up to three cusps).Pharyngobranchial 4 teeth small, continuing dentition pattern of pharyngobranchial 3, about eight rows.
One supraneural, anterior to first neural spine.Abdominal ribs 13 pleural, first on third vertebra, last two decreasing in length; 11 epineural, first on first vertebra.Caudal ribs continuing pleural series, 8-10; caudal ribs bifurcate dorsally but not ventrally (observed in c&s specimen, not visible in X-radiographs); strongly decreasing in size until last rib, which is not more than a small nodule.
All caudal vertebrae attached to caudal prolongations of swim bladder (one on each side, observed in c&s specimen).Vertebrae 14+16(1), 14+17(5), 15+15(4); long hypapophyses fused ventrally, restricted to third abdominal vertebra; anteriormost caudal vertebra with hemal spine plus pair of basapophyses; two posteriormost abdominal vertebrae with basapophyses contacting medially; five posteriormost centra totally included in caudal peduncle; seventh and eighth posteriormost vertebrae with an anterior expansion on hemal spine apparently for articulation with last ribs.Color in alcohol.Background color yellowish pale brown, darker over lachrymal, nasal, premaxilla (including upper lip), frontal bones and nape; lighter over dentary and angulo-articular bones and in region between ventral edge of cleithrum and posterior margin of basipterygium (Fig. 1).Throat dark.Few specimens with a few dark marks on sides of head, corresponding to iridescent blue marks of live specimens.Flanks little darker dorsally than ventrally, with six grayish-brown vertical bars from dorsal-fin base to E0 scale row, fading two rows below.Dorsal end of each bar in relation to dorsal-fin rays as follows: first, between nape and first spine; second, between fifth and tenth spines; third, between 11 th and 16 th spines; fourth, between third and seventh soft rays; fifth, around last soft ray; sixth, slightly behind midpoint of caudal peduncle.Some individuals without visible bars, most with only bars 1, 2, and 3 visible.Bars inclined, their dorsal ends more anterior than ventral ends.Melanophores forming vertical bars located underneath scales, imbedded in dermis.An amorphous black spot on each bar, coinciding with E1 and E2 scale rows; spot on second bar corresponding to midlateral spot, always present; spots on bars 1, 3, 4, 5, and 6 absent in some individuals.Melanophores forming all spots located both in dermis and epidermis; dermal melanophores equally spread within round area; epidermal melanophores forming several clusters (Figs.1-2) in larger individuals, equally spread within round area in smaller ones.Pectoral fin hyaline.Dorsal, caudal, anal, and pelvic fins with pale gray, somewhat brownish ground color.Dorsal fin with oval, unpigmented spots over inter-radial membranes of last four or five soft rays, their long axis parallel to radial axis.In some individuals, similar marks can be observed among all soft rays, seemingly forming two very faint stripes parallel to dorsal profile of body.Caudal fin ground color a little darker than dorsal fin, particularly in middle inter-radial membrane.Proximal portion of caudal fin with spots of same color, shape and orientation as in dorsal fin, but distally spots gradually fuse, appearing as longitudinal parallel stripes over distalmost third.Anal and pelvic fins with even darker ground color, with faint light, unpigmented stripes (about four or five).Anal-fin stripes almost horizontal, slightly descending posteriorly, axis not corresponding to radial axis, contrasting with pelvic-fin stripes.Very large specimens with faint vertical bars on flank, black spots with clusters of melanophores more scattered, darker head and throat.Young with black spots rounded, not scattered, and caudal fin sometimes without longitudinal light stripes.Very young individuals with light dots forming vertical bars on caudal fin.

Color in life.
Eyes brownish gray, with light yellow ring around pupil.Head dorsally brownish gray from upper lip until between eyes.Side of head brownish orange, covered by bluish iridescent vermiculations and spots, sometimes rings, all over opercle, subopercle, preopercle, cheek and lachrymal.Some vermiculations united into stripes along infraorbitals, preopercle, angulo-articular and margin between opercle and subopercle.Lower lip, lower jaw and skin over interopercle pale gray.Intermandibular region and ventral portion of branchiostegal membrane gray to dark gray.Flank ground pale gray dorsally, becoming white ventrally.Center of each scale with bluish iridescent spot, seemingly forming a longitudinal stripe along each scale row.Margin of each scale orange, seemingly forming zigzag longitudinal stripes between scale rows.Black spots of flank scattered, permeated by bluish iridescent spots.Prepelvic area and area between pelvic and pectoral fins covered by scattered yellow to orange spots.Pectoral fin hyaline.Other fins with same ground color as head, light (unpigmented) marks observed in alcohol-preserved specimens appearing as bluish-iridescent.
Spinous portion of dorsal fin translucent, gray.Young with only a few faint vermiculations on side of head, prepelvic region white and anal fin uniformly orange (Figs. 2, 5).
Distribution.Geophagus mirabilis is known from the rio Aripuanã drainage, upstream from Dardanelos/Andorinhas falls (Fig. 6).Etymology.Named in reference to the unique color pattern that includes the row of black spots on the flanks and the iridescent spots and vermiculations on the side of the head in living individuals; the Latin adjective mirabilis means extraordinary, marvelous, admirable.
Remarks.Specimens from MZUSP 114760 were excluded from the type series because of the very small size and bad preservation, but likely represent Geophagus mirabilis.
Monophyly of Geophagus is well established by morphological (Kullander, 1998) and molecular (López-Fernández et al., 2005) analyses.Geophagus is unique among cichlids because it has long posterior swim bladder diverticles supported by short ribs continuing the pleural series as far as the 9 th to 16 th hemapophysis (Kullander, 1998).Species taxonomy so far has been based on the color pattern, particularly the suborbital mark, the size and position of the midlateral spot, the number of vertical bars on the side, and the color pattern on the caudal fin, as well as the width of the exposed portion of the gill blade (Kullander, 1986;Kullander & Nijssen, 1989;López-Fernández & Taphorn, 2004).
All species in Geophagus present a large dark brown or black spot on the middle of the side, the midlateral spot.In addition to subtle differences in size and among the species, the only significant variation known until now was the ontogenetic variation of that spot in G. altifrons, in which it becomes progressively smaller with increasing body size and may be absent in large specimens.The midlateral spot is also present in G. mirabilis, but in this species, it is one of a series of spots along the side.This coloration pattern resembles that of South American cichlids in general, in which there are usually a midlateral spot and/or a row of spots and a dark horizontal band along the middle of the side.Among geophagine cichlids, the coloration pattern of G. mirabilis is very similar to that of other species in the rio Madeira drainage, viz.Satanoperca pappaterra (Heckel), which has a series of blackish spots along the middle of the side and along the dorsum (Heckel, 1840).This color pattern is unique within Satanoperca.Satanoperca pappaterra has so far been found only in the rio Guaporé basin, in Brazil and Bolivia, and in the upper rio Paraguay basin, in Brazil and Paraguay.Its geographical range is thus completely separated from that of G. mirabilis.The color pattern in life of G. mirabilis also shows a very unusual character in Geophagus.The presence of light bluish reflecting spots and vermiculations on the side of the head resembles the pattern present in many South American cichlids, including some species of Satanoperca (Stawikowski & Werner, 2004), but has not been recorded in any other species in Geophagus.
Geophagus mirabilis has relatively large scales, 4½-5½ between superior lateral line and first dorsal-fin spine and 29-31 in the E1 row, which is unusual among Geophagus species, which always have 6½ or more scale series above the lateral line and usually more than 31 E1 scales, and more similar to the counts recorded for species of Satanoperca, as in Kullander & Ferreira (1988).Low numbers of E1 scales overlapping with G. mirabilis are found in G. grammepareius (30-31; río Orinoco basin), G. camopiensis (30-32; Oyapock, Approuague, and Amapari river basins), Geophagus parnaibae ; rios Parnaíba and Mearim basins), G. taeniopareius (31-33; río Orinoco basin), G. harreri (31-34; Marowijne River basin) and Geophagus neambi (30-34; rios Tocantins-Araguaia basin).In their attempt to identify monophyletic groups within Geophagus, Staeck & Schindler (2006: 74) used low scale counts in combination with a low modal number (7) of anal-fin soft rays to define two "clades" within the "Geophagus surinamensis complex" distinguished by López-Fernández & Taphorn (2004).One of them would be composed of G. camopiensis and G. parnaibae, which had the lowest counts.This hypothesis was not based on a phylogenetic analysis, however, and no character state was presented to support monophyly of the remaining species in the G. surinamensis "complex".The "Geophagus surinamensis complex" was distinguished by López-Fernández & Taphorn (2004) for species traditionally identified as G. surinamensis and characterized by a deep body and head, a large midlateral spot and the suborbital stripe in adults either absent or represented by a dark mark at the corner of the preopercle.They contrasted it to more elongate species with a prominent vertical stripe from the eye to the preopercle but did not attempt a phylogenetic analysis.Geophagus mirabilis clearly falls into the former category, but there is no support for relationships with G. camopiensis or G. parnaibae.As shown above, there is a gradual variation in scale counts from the lowest in G. mirabilis to the maximum of 38 in G. dicrozoster, and no obvious non-arbitrary natural break point.
Geophagus mirabilis is restricted to a long stretch of the rio Aripuanã basin from right above the Dardanelos/ Andorinhas falls to many kilometers upstream, and it is the only species in the genus that occurs upstream from the falls.Kullander (1995) listed 10 fish species (including G. mirabilis) known from the upper rio Aripuanã, including the entire upstream stretch and, in some cases, a distance of few kilometers downstream from Dardanelos/Andorinhas falls, as well as its tributaries that drain into those stretches.From that list of species, Lasiancistrus scolymus Nijssen & Isbrücker (Loricariidae) is now considered a synonym of the widespread L. schomburgkii (Günther) (Armbruster, 2005); and Crenicichla guentheri Ploeg has been synonymized with the local endemic C. hemera Kullander (Varella et al., 2012).A species overlooked by Kullander (1995), Utiaritichthys longidorsalis Jégu, Tito de Morais & Santos (Serrasalmidae), and the recently described Trachycorystes menezesi Britski & Akama (Auchenipteridae) and Hypostomus dardanelos Zawadzki & Carvalho (Loricariidae) should be added to the list, changing the number of valid species considered endemic to that region to 11, including Geophagus mirabilis (Jégu et al., 1992;Britski & Akama, 2011;Zawadzki & Carvalho, 2014).If we consider all of the species thought to be endemic to the rio Aripuanã basin as a whole, the number rises to at least 15 (Rocha et al., 2008a(Rocha et al., , 2008b;;Zanata & Ohara, 2009;Ribeiro et al., 2011;Eschmeyer, 2014).The fish fauna of the upper rio Aripuanã may be more closely related to that of the adjacent rio Tapajós headwaters.Varella et al. (2012) suggested that the cichlid Crenicichla hemera in the upper rio Aripuanã may be the sister species of the locally endemic C. chicha Varella, Kullander & Lima in the adjacent rio Juruena.Netto-Ferreira et al. (2009) described Jupiaba yasi Netto-Ferreira, Zanata, Birindelli & Sousa from the rio Teles-Pires drainage and from the rio Aripuanã immediately dowstream of the Dardanelos/Andorinhas falls.Curiously, it has not been reported from the rio Juruena headwaters so far.Specimens of Geophagus from the rios Juruena and Arinos represent a deep-bodied species with a midlateral spot but no further dark spots on the side, nine circumpeduncular scales ventral to the lateral line, and approximately 35 scales in the E1 row.No additional species in Geophagus have been reported from the rio Juruena.

Fig. 6 .
Fig. 6.Map of the geographic distribution of Geophagus mirabilis.Star corresponds to type-locality; circles correspond to other localities where the species is found.One symbol can correspond to more than one locality.

Table 1 .
Morphometric data for holotype and 19 paratypes of Geophagus mirabilis, new species.SD = standard deviation.