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aqua, International Journal of Ichthyology

Austrolebias bagual, a new species of annual fish (: ) from southern Brazil

Matheus Vieira Volcan 1,2, Luis Esteban Krause Lanés1,3 and Ândrio Cardozo Gonçalves1

1) Instituto Pró-Pampa (IPPampa), Laboratório de Ictiologia. Pelotas, Rio Grande do Sul, Brasil. E-mail: [email protected] 2) Universidade Federal de Santa Maria (UFSM). Programa de Pós Graduação em Biodiversidade . Santa Maria, Rio Grande do Sul, Brasil. 3) Universidade do Vale do Rio dos Sinos (UNISINOS), Programa de Pós Graduação em Biologia: Diversidade e Manejo da Vida Silvestre, Laboratório de Ecologia e Conservação de Ecossistemas Aquáticos, São Leopoldo, Rio Grande do Sul, Brasil.

Received: 22 September 2014 – Accepted: 10 July 2014

Abstract adloffi por la altura inferior del cuerpo y cabeza (excepto en bagual, a new species of annual fish closely re- A. reicherti), más corta longitud de la base de la aleta anal y lated to the A. adloffi species group, is described from spec- tamaño de la aleta caudal en los machos, y la altura de la imens collected from temporary ponds located in the mid- cabeza más baja (excepto en A. reicherti) y el tamaño de la dle course of the Rio Camaquã, Laguna dos Patos system at aleta anal en las hembras. Por otra parte, las hembras de A. the municipality of Encruzilhada do Sul, Rio Grande do bagual no presentan un par de manchas negras dispuestas Sul, Brazil. The new species is distinguished from other verti calmente en la parte posterior del pedúnculo caudal, Austrolebias species by the unique male pigmentation pat- típico de la mayoría de las especies del grupo A. adloffi. tern of the dorsal fin, with black vertical bars elongated from the base to the medial portion of the fin, and by the Resumo pattern of transversal black bars on the body, which become Austrolebias bagual, uma nova espécie de peixe anual estre- gradually shorter and fainter towards caudal peduncle. It is itamente relacionada com o grupo de espécies A. adloffi é de- also distinguished from all species of the A. adloffi species scrita com base em indivíduos coletados de poças tem- group by the lower body depth and head (except in A. rei- porárias localizadas na bacia do médio curso do Rio Cama- cherti), lower anal fin base length and caudal fin length in quã, sistema da Laguna dos Patos, município de Encruzilha- males, and the lower head depth (except in A. reicherti) and da do Sul, Rio Grande do Sul, Brasil. A nova espécie dis- anal fin base length in females. In addition, A. bagual fe- tingue-se de todas as espécies de Austrolebias pelo padrão de males do not have the pair of black spots arranged vertically colorido único de machos que consiste de barras verticais pre- in close proximity on the posterior portion of caudal pe- tas alongadas da base à porção medial da nadadeira dorsal e duncle typical of most species of the A. adloffi group. pelo padrão de barras transversais do corpo, que tendem a se tornar gradualmente mais curtas e desaparecer na porção pos- Resumen terior. Também se distingue de todas as espécies do grupo A. Austrolebias bagual, una nueva especie de pez anual es- adloffi pela menor altura do corpo e da cabeça (exceto em A. trechamente relacionada al grupo de especies A. adloffi se de- reicherti), menor comprimento da base da nadadeira anal e scribe de charcos temporales ubicadas sobre el curso medio tamanho da nadadeira caudal em machos, e pela menor al- de la cuenca del río Camaquã, sistema de la Laguna dos tura da ca beça (exceto em A. reicherti) e tamanho da base da Patos, municipio de Encruzilhada do Sul, Rio Grande do nadadeira anal em fêmeas. Além disso, fêmeas de A. bagual Sul, Brasil. La nueva especie se distingue de todas las demás não apresentam um par de pontos negros dispostos vertical- especies de Austrolebias por el patrón de color único de los mente na porção posterior do pedúnculo caudal, típico da machos que consiste en bandas negras verticales alargadas maioria das espécies do grupo A. adloffi. desde la base hasta la parte media de la aleta dorsal y el pa- trón de bandas transversales del flanco que tienden a ser más Zusammenfassung corto y desaparecer en la parte posterior del cuerpo. Tam- Die neue Art Austrolebias bagual, die mit der A.-adloffi- bién se distingue de todas las especies del grupo A. Artengruppe nahe verwandt ist, wird auf der Grundlage von

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Austrolebias bagual, a new species of annual fish (Cyprinodontiformes: Rivulidae) from southern Brazil

Exemplaren beschrieben, die in zeitbegrenzten Tümpeln am mine e la minore lunghezza della pinna caudale nei maschi. Mittellauf des Rio Camaquã, Laguna dos Patos, in der Kom- Inoltre, nelle femmine di A. bagual non è presente la coppia mune Encruzilhada do Sul, Rio Grande do Sul, in Brasilien di macchioline nere disposte verticalmente in prossimità del- gefunden wurden. Von anderen Austrolebias-Arten unter- la porzione posteriore del peduncolo caudale tipica della scheidet sich die neue Art durch das einzigartige Farbmuster maggior parte delle specie del gruppo A. adloffi. der Rückenflosse bei den Männchen, mit schwarzen senkrechten Streifen, die sich vom Ansatz bis zum mittleren Teil der Flosse erstrecken, sowie durch die schwarzen Quer- INTRODUCTION streifen auf dem Rumpf, die zum Schwanzstiel hin immer The Neotropical Austrolebias comprises kürzer und schwächer werden. Unterscheidungsmerkmale zu about 40 small annual (Costa 2006; allen anderen Arten der A.-adloffi-Artengruppe sind außer- Loureiro et al. 2011; García et al. 2014) distrib- dem die geringere Tiefe von Rumpf und Kopf (Ausnahme A. uted in southern Brazil, southern Bolivia, reicherti), die geringere Länge der Afterflossenbasis und der Schwanzflosse bei Männchen sowie die geringere Kopftiefe Paraguay, Uruguay and north-eastern Argentina (Ausnahme A. reicherti) und Afterflossenlänge bei Weibchen. (Costa 2010). Species of this genus inhabit natural Hinzu kommt, dass bei den Weibchen von A. bagual das Paar temporary ponds in many river drainages in this re- schwarzer, senkrecht angeordneter Flecken fehlt, die bei den gion, including the Paraná-Paraguay-Uruguay river meisten Arten der A.-adloffi-Gruppe dicht beieinander auf system and the Patos-Mirim lagoon system (Costa dem hinteren Teil des Schwanzstiels zu finden sind. & Cheffe 2005). In the Pampas region, ponds are usually formed during the winter months (June-Ju- Résumé ly), whereas in the Chaco region they are mainly Austrolebias bagual, une nouvelle espèce de poisson annuel formed during the summer months (December- proche du groupe d’espèces d’A. adloffi, est décrit sur base de January) (Costa 2006). spécimens collectés dans des mares temporaires situées sur le The highest diversity of Austrolebias (23 species) cours moyen du Rio Camaquã, Lagua dos Patos, dans la mu- nicipalité d’Encruzilhada do Sul, Rio Grande do Sul, Brésil. has been recorded in the Rio Grande do Sul State in La nouvelle espèce se distingue des autres espèces d’Aus- southern Brazil (Lanés et al. 2013; 2014; Volcan et trolebias par le patron de pigmentation unique de la dorsale al. 2014). These species are severely threatened with chez le mâle, avec des barres verticales noires de la base à la extinction because of their low dispersal ability and portion médiane de la nageoire et par le patron de barres the extensive loss and fragmentation of freshwater transversales noires sur le corps, qui deviennent graduelle- wetlands and temporary ponds. Furthermore, their ment plus courtes et moins marquées vers le pédoncule cau- peculiar lifecycle and restricted range contribute to dal. Elle se démarque également de toutes les autres espèces this threat (Reis et al. 2003; Rosa & Lima, 2008; du groupe d’A. adloffi par une hauteur de corps moindre et de la tête (sauf pour A. reicherti), par une longueur moindre Volcan et al. 2010, 2011a, 2011b, 2014; ICMBio de la base de l’anale et de la caudale pour les mâles et une 2013; Lanés et al. 2013, 2014). hauteur de tête moindre (sauf pour A. reicherti) ainsi que par The genus has been phylogenetically redefined by la base de l’anale des femelles. En outre, les femelles d’A. Costa (2006) to include the species previously re- bagual n’ont pas la paire de taches noires placées verticale- ferred to as Megalebias Costa. In Costa’s review, ment l’une très près de l’autre sur la portion postérieure du three basal species and five species-groups were de- pédoncule caudal, ce qui est typique pour la plupart des es- fined, among them the groups pèces du groupe d’A. adloffi. and A. bellottii. García et al. (2014) reinforce the existence of these two groups, however, they differ Sommario Austrolebias bagual, una nuova specie di pesci annuali stret- from that proposed by Costa (2006) by allocating tamente legato al gruppo di specie A. adloffi, è descritto da A. arachan Loureiro, Azpelicueta & García 2004 campioni raccolti in stagni temporanei situati nel medio cor- and A. viarius (Vaz-Ferreira, Sierra de Soriano & so del Rio Camaquã, Laguna dos Patos nel comune di En- Scaglia de Paulete, 1965) to the A. adloffi species cruzilhada do Sul, Rio Grande do Sul, Brasile. La nuova group, which were previously included in the A. specie si distingue dalle altre specie di Austrolebias per l’origi - bellottii species group (Costa 2006). nale profilo di pigmentazione della pinna dorsale del mas- The A. adloffi species group is distinguished from chio, caratterizzato da barre verticali nere allungate dalla base remaining taxa in Austrolebias by unique color pat- alla porzione mediale della pinna, e per la presenza di barre nere trasversali sul corpo, che diventano gradualmente più tern on posterior portion of caudal peduncle in ju- brevi e più indistinte verso il peduncolo caudale. Si distingue veniles and adult females, and occasionally in adult anche da tutte le specie del gruppo A. adloffi per la minore al- males, consisting of a pair of black spots arranged tezza del corpo e della testa (eccetto in A. reicherti), la minore vertically (except in A. arachan and A. viarius) lunghezza della base della pinna anale nei maschi e nelle fem- (Costa 2006). We herein describe a new species,

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which is closely related to the A. adloffi species Abranjo, close to BR-471 highway (30°51’12” S, group. Additionally, we provide summarized infor- 52°34’16” W), Aug. 2012, M. V. Volcan, L. E. K. mation on the population parameters, habitat Lanés & G. M. Wallwitz. characteristics and conservation status of this new, Paratypes: All from Brazil, Rio Grande do Sul, En- rare and threatened Rivulidae species. cruzilhada do Sul: MCP 48241, 5 males (1 C&S), 25-32.1 mm SL, 5 females (1 C&S), 22.5-38.3 MATERIALS AND METHODS mm SL, collected with the holotype. Morphological characters were obtained from Diagnosis: Austrolebias bagual can be uniquely di- specimens fixed in formalin after collection, and agnosed from all other species of Austrolebias by the subsequently transferred to 70% ethanol. Fish unique colour pattern on the body and dorsal fin measurements were taken point-to-point with dig- in males. This usually consists of an overall light ital calipers to the nearest 0.1 mm on the left side brown to dark brown coloration with 3-6 dark of the specimen following Costa (1995, 2006). grey, narrow vertical bars, bars becoming gradually Measurements are expressed as percents of stan- shorter and fainter towards caudal peduncle (vs. dard length (SL), except the head measurements, never similar colour patterns), and dorsal fin light which are recorded as percents of head length. Fin- bluish-green, with 5-7 black vertical bars extending ray counts include all elements. Numbers of verte- from the base to the medial portion of the fin (vs. brae were recorded only from cleared and stained absence of a such pattern in the remaining Aus- specimens (C&S) according to the method de- trolebias). In addition, A. bagual females lack the scribed in Taylor & Van Dyke (1985). Frontal pair of black spots arranged vertically in close prox- squamation nomenclature follows that described imity on the posterior portion of the caudal pedun- by Hoedeman (1958), and the cephalic neuromast cle, sometimes coalescing to form an 8-shaped series are described according to Costa (2006). blotch, which is typical of most of the A. adloffi Descriptions of color patterns were based both on species group (except A. arachan and A. viarius). direct examination of live specimens in the field For additional morphometric and meristic charac- just after collection and on live specimens pho- ters distinguishing Austrolebias bagual from con- tographed in the field, fixed in situ after photos, geners, see the Discussion, below. and one couple maintained in aquaria (not pre- Description: Morphometric and meristic data are served). Institutional abbreviations are MCP presented in Table I. Males are larger than females; (Museu de Ciência e Tecnologia da Pontifícia Uni- largest male examined 39.3 mm SL, largest female versidade Católica do Rio Grande do Sul, Porto 38.3 mm SL. Dorsal profile slightly convex from Alegre). Species groups names follow those de- snout to end of dorsal-fin base, straight on caudal scribed by Costa (2006) and Gárcia et al. (2014). peduncle. Ventral profile gently arched from lower Conservation status assessment was based on field jaw to origin of anal fin base, nearly straight on surveys. To establish the vulnerability category, the caudal peduncle. Greatest body depth between IUCN criteria were applied (IUCN 2014) using cri- pelvic-fin base and urogenital papilla. Body deep terion B2 (Geographic range in the form of either and compressed. Eye positioned on lateral portion B2 - area of occupancy). Currently, this approach is of head. Snout blunt and jaws short. applied in the evaluation of the red lists of threat- Dorsal-fin rays in males 19-23; in females 15-19. ened fauna in Brazil (ICMBio 2013) and Rio Dorsal and posterior tip of dorsal fin of males Grande do Sul state (FZB 2014). The area of occu- rounded. Origin of dorsal fin at vertical through pancy (AOO) was estimated using satellite images neural spines of 8th and 9th vertebrae in males, in available in Google Earth (earth.google.com). females through neural spines of 11th and 12th ver- tebrae. Anal-fin rays in males 21-25; in females 17- 21. Anal-fin tip rounded in males. Anal and dorsal Austrolebias bagual n. sp. fins with short filaments extend along the distal (Figs 1-3) border in males. Anteromedian rays of anal fin of females elongated, anal fin shape nearly triangular. Holotype: MCP 48240, male, 39.3 mm SL, Brazil, Anal-fin origin at vertical through 3rd and 5th dor- Rio Grande do Sul State, Encruzilhada do Sul mu- sal-fin rays in males and through the 2nd and 3rd in nicipality, Laguna dos Patos system, Rio Camaquã females. Origin of anal fin at vertical through basin, temporary pond in the floodplains of Arroio pleural ribs of 9th and 10th vertebrae in males, in

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A

B

Figs 1A-B. A. Holotype (MCP 48240). B. Live female paratype (MCP 48241) of Austrolebias bagual sampled from a tem- porary pond of the Arroio Abranjo floodplain. Photos by M. V. Volcan

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Table I. Morphometric data for the holotype and paratypes of Austrolebias bagual.

Male (n=5) Female (n=5) –– Morphometric data Holotype min max χ DP min max χ DP

Standart length 39.3 25.3 32.1 29.9 2.7 22.5 38.3 30.1 5.8 Percentages of standart length Body depth 33.8 23.4 31.3 27.7 3.2 18.3 35.4 26.7 6.8 Caudal peduncle depth 14.8 9.7 12.7 11.2 1.3 7.9 13.0 10.5 2.2 Predorsal length 52.7 36.4 46.8 42.9 4.0 34.4 61.6 47.4 10.2 Prepelvic length 48.9 32.1 38.9 36.0 2.9 28.5 52.4 39.7 9.0 Dorsal-fin base length 37.9 22.1 31.0 28.5 3.7 15.5 27.0 20.7 4.3 Anal-fin base length 36.4 22.1 30.0 27.0 3.1 12.5 20.1 17.3 2.9 Caudal-fin length 19.6 16.5 20.9 18.5 1.7 17.3 23.2 19.2 2.4 Pectoral-fin length 22.9 15.5 23.7 19.8 3.0 13.5 27.7 18.6 5.6 Pelvic-fin length 7.9 4.6 12.0 7.4 2.8 5.3 12.7 8.4 3.0 Head length 30.5 22.1 27.7 25.9 2.6 19.6 29.0 25.3 4.2 Percentages of head length Head depth 98.3 85.3 95.4 89.7 4.9 83.1 93.9 86.4 4.3 Head width 64.2 55.2 64.2 61.2 4.2 59.7 68.4 62.9 4.0 Snout length 15.0 11.1 14.7 12.8 1.5 11.5 14.3 13.3 1.3 Lower jaw length 22.5 18.5 28.7 23.8 4.2 21.1 23.4 22.1 1.1 Eye diameter 24.2 18.3 28.4 24.0 3.6 21.8 27.2 24.2 2.0 females through pleural ribs of 11th-12th vertebrae. 3-4, anterior rostral 1, posterior rostral 1, infraor- Caudal fin distal margin rounded, with 22-24 rays bital 18-22, preorbital 1-2, otic 1-6, postotic 2-3, in males and 22-26 fin rays in females. Caudal-fin supratemporal 1, median opercular 1, ventral oper- rays supported by last four vertebrae. Pectoral-fin cular 2, preopercular 18-23, mandibular 10-14, rays 11-13 in males, 12-13 in females; Pectoral-fins lateral mandibular 3-5. elliptical. Pectoral-fin posterior tip reaching from Six branchiostegal rays. Dermosphenotic ossifica- the origin of the pelvic fin to the 4th anal-fin ray in tion absent. Urohyal deep. Total number of verte- males, from the origin of the pelvic fin to the uro- brae 28-29, 10-11 precaudal. genital papilla in females. Five pelvic-fin rays. Color in life (Figs 1 and 2): Males: Light Pelvic-fin posterior tip from 2nd to 3rd anal-fin ray brown to dark brown body side with generally 3-6 in males, from 1st to 2nd anal fin ray in females. dark grey vertical bars that become gradually short- Pelvic fins joined to each other, with medial pelvic- er and fainter towards caudal peduncle. Typically, fin membranes coalesced at different degrees. Uro- first 2-3 bars more conspicuous. Sometimes, the genital papilla not attached to anal fin. anterior region of the body pale golden. Vertical Scales cycloid. Body and head entirely scaled, ex- bars three to five times narrower than the inter- cept anterior ventral surface of the head. One row space width. Number of vertical bars can be un- of scales on anal-fin base. Three rows of scales on equal between sides of body. Abdominal region caudal-fin base. Frontal squamation F and G pat- pale golden. Infraorbital bar black, wider near the terned; scales arranged in transverse pattern, all eye. Supraorbital bar black, with distinctive narrow scales with exposed posterior margin. Longitudinal extension over the neuromast parietal series. Iris or- series of scales 29-32; transverse series of scales 12- ange, with a dark bar though centre of the eye. Op- 15; scale rows around caudal peduncle 13-15. ercular region bright bluish-green. Dorsal fin Minute contact organs throughout body, more bluish-green with 5-7 black vertical bars extending conspicuous on ventral region of males. Row of from the base to the medial portion of the fin, in- minute contact organs in the two uppermost pec- terspersed with subtle, yellowish-white bars. Cau- toral-fin rays and on distal portion of anteriormost dal, anal and pelvic fins light bluish-green. No anal-fin rays. No contact organ on pelvic, dorsal spots, dots or bars in caudal, pelvic and anal fins. and caudal fins. Narrow black stripe on margin of anal fin, incon- Cephalic neuromasts: supraorbital 16-19, parietal spicuous in some specimens. Pectoral fins hyaline,

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with narrow black ventral margin extending from type locality, in the Encruzilhada do Sul municipali- the fin base to the tip of the sixth or seventh ven- ty, from a small temporary pond (Fig. 4) at an alti- tralmost rays. tude of 46 m, associated with the floodplain of the Females: Overall color pattern light yellowish- Arroio Abranjo, in the middle course of the Rio Ca- brown, with scattered dark grey or dark brown maquã basin, Laguna dos Patos system, in flat areas spots. Venter pale golden. Opercular region pale surrounded by hills in geomorphological units of the yellowish or pale greenish-blue. Unpaired fins hya- Crystalline Shield of the Rio Grande do Sul State. line with light brown and spots bars on the basal Etymology: The term bagual refers to an expres- portion of the dorsal, anal and caudal fins. Pectoral sion used by the Brazilian gaúcho (people living in and pelvic fins hyaline. Iris orange, with dark bar Rio Grande do Sul State) which means a horse that through centre of eye. Supra and suborbital bars has not been castrated. However, for gaúcho’s cul- dark grey and inconspicuous. ture, it is also an adjective used as a synonym for Distribution: Austrolebias bagual is known only for being brave, courageous, fearless and audacious, as is the case here. Because these annual fish have unique adaptations for living in an extreme envi- A ronment (the pond dries up completely during some months of the year) and have been discovered in a remote and isolated area, we consider the new species ‘bagual’. A name in apposition. Habitat notes: The locality of occurrence of A. bagual is situated in the Pampa region, which has an irregular rainy season between May and No- vember, with annual precipitation reaching about 1,600 mm per year (Nobre et al. 1986). During B drier periods, the ponds dry out. The population of A. bagual is essentially restrict- ed to open field habitat (grassland areas), in a small (area less than 1 ha), shallow environment that is exposed to direct light and dense aquatic vegeta- tion in the floodplain of the Arroio Abranjo (Fig. 5). Pond vegetation is composed of emergent and submerged species of macrophytes. The pond has brownish-transparent water 15 cm deep, and a mud substrate. Water sample parameters are as fol- - C lows: pH: 5.17; dissolved oxygen: 5.49 mg/L 1; conductivity: 17 µS/cm; total dissolved solids: 9 ppm; and a reduced area of occupancy (AOO) of about 1,000 m². In the sampled pond, A. bagual co-occurs with another two non-annual fish: Corydoras paleatus (Jenyns, 1842) and Cheirodon interruptus (Jenyns, 1842). Population parameters and conservation status: The species shows low population density. In the pond with the occurrence of A. bagual, the CPUA was found to be 0.18 fishes per m². Samples taken in November 2013 and June 2014 did not succeed in recording new specimens, although the environ- Figs 2A-C. Color variation of live males of Austrolebias bagual, Encruzilhada do Sul, Rio Grande do Sul, Brazil. ment was still flooded and the conditions were ap- A. Holotype (MCP 48240), B. Paratype (MCP 48241), propriate for their occurrence. Males tend to occur C. Specimen kept in aquaria, not preserved. Photos by M. at higher density than females, with a sex ratio of V. Volcan 1.2:1 (M:F).

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The type locality of A. bagual is an ‘island’ in the bagual is considered a ‘Critically Endangered’ middle of a fully modified area that is on the verge species, as it is included in the criteria CR B2ab (ii, of being destroyed, even more so considering the iii). The species presents reduced AOO (less than 1 agricultural focus of the region. The sampled pond km²), the populations are severely fragmented (a) was under the indirect influence of plantations of and a continued decline (b) in AOO (ii) and qual- rice, wheat and soy. However, the region of occur- ity of habitat (iii). rence of the species is dominated mainly by large plantations of rice, especially in the low areas of the DISCUSSION floodplain of the Rio Camaquã. The new species presents all of the synapomor- Beyond these impacts, the impoundment of rivers phies of the genus Austrolebias and is related to the is an activity that also deserves attention for its pos- A. adloffi species group through the possession of a sible influence on A. bagual populations, since long and triangular anal fin in females, two to four there are hydroelectric projects planned for the parietal neuromasts and the presence of a black basin. In accordance with the IUCN criteria, A. ventral margin in the pectoral fins of males (except

A

B

Fig. 3A-B. A. Holotype (MCP 48240). B. Female paratype (MCP 48241) of Austrolebias bagual, after preservation, Encruzil- hada do Sul, Rio Grande do Sul, Brazil. Photo by M. V. Volcan.

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Fig. 4. Occurrence of Austrolebias bagual, showing the type locality (asterisk) in the Arroio Abranjo floodplain, Rio Camaquã basin, Laguna dos Patos system, southern Brazil.

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in A. viarius) (see Costa 2006). However, the length (21.1-23.4% HL vs. 19.0-20.2% HL), low- colour pattern of the body and dorsal fin of males er head depth (83.1-93.9% HL vs. 101-112% easily distinguish A. bagual from any congener. HL), lower anal-fin base length (12.5-20.1% SL Moreover, the females of A. bagual do not present vs. 25.5-35.7% SL), higher number of scales in the pair of black spots arranged vertically in close longitudinal series (29-32 vs. 26-28) and smaller proximity on the posterior portion of the caudal number of horizontal scales around the caudal pe- peduncle, sometimes coalescing to form an 8- duncle (14-15 vs. 16). shaped blotch, which is typical of most of the A. Males of A. bagual differ from males of A. nachti- adloffi species group (Costa 2006). galli Costa & Cheffe, 2006 by the lower body depth In addition to the diagnostic characters presented (23.4-33.8% SL vs. 37.4-42.6% SL) and head in the Diagnosis, A. bagual males differ from those (85.2-98.3 % HL vs. 113.7-132% HL), lower anal- of A. adloffi (Ahl, 1922) by the lower body depth fin base length (22.1-36.4% SL vs. 40.5-49.6% (23.4-33.8% SL vs. 40.4-44.2% SL) and head SL), lower caudal-fin length (16.5-20.9% SL (85.2-98.3% HL vs. 106.5-127% HL), lower anal vs.26.9-31.5% SL) and smaller number of scales fin base length (22.1-36.4 SL vs. 44.3-49.5% SL), around caudal peduncle in males (13-15 vs. 16), lower caudal fin length (16.5-20.9% SL vs. 30.3- smaller dorsal-fin base length (22.1-37.9% SL vs. 36.8% SL) and smaller number of scales around 38.0-42.3% SL), lower head width (55.2-64.2% caudal peduncle in males (13-15 vs. 16), lower pec- HL vs. 66.6-71.4% HL) and higher number of toral fin length (15.5-23.7% SL vs. 26.4-30.6% scales in longitudinal series (29-32 vs. 26-28). Fe- SL), lower eye diameter (18.3-28.4% HL vs. 28.5- males differ by lower body depth (18.3-35.4% SL 34.0% HL), smaller number of horizontal scales vs. 37.0-42.6% SL), lower caudal peduncle depth around the caudal peduncle (13-15 vs. 16), lower (7.9-13.0% SL vs. 13.3-15.5% SL), lower eye di- preopercular neuromasts (19-23 vs. 31-38) and tip ameter (21.8-27.2% HL vs. 30.4-34.6% HL), low- of the pectoral fin reaching the 3rd to 4th anal-fin er head depth (83.1-93.9% HL vs. 107.7-115% ray (vs. 5th to 8th). Females of A. bagual differ from HL), lower anal-fin base length (12.5-20.1% SL vs. females of A. adloffi by presenting higher lower jaw 14.9-32.2% SL), smaller number of horizontal lengths (21.1-23.4% HL vs. 17.8-19.0% HL), scales around the caudal peduncle (14-15 vs. 16), lower head depth (83.1-93.9% HL vs. 101.4- higher lower jaw length (21.1-23.4% HL vs. 15.8- 118% HL) and anal-fin base length (12.5-20.1% 20.2% HL) and higher number of scales in longitu- SL vs. 30.6-33.5% HL), higher number of scales in dinal series (29-32 vs. 26-28). longitudinal series (29-32 vs. 26-28), lower eye di- Males of A. bagual differ from A. charrua Costa & ameter (21.8-27.2% HL vs. 30.3-25.5% HL), Cheffe, 2001 males by the lower body depth (23.4- smaller number of horizontal scales around the 33.8% SL vs. 39.1-45.1% SL) and head (85.2- caudal peduncle (14-15 vs. 16) and lower preoper- 98.3% HL vs. 113.6-138% HL), lower anal-fin cular neuromasts (18-20 vs. 31-38). base length (22.1-36.4% SL vs. 43.7-48.5% SL), Males of A. bagual differ from males of A. nigro- lower caudal-fin length (16.5-20.9% SL vs. 29.3- fasciatus Costa & Cheffe, 2001 by the lower body 39.6% SL) and smaller number of scales around depth (23.4-33.8% SL vs. 38.7-44.2) and head caudal peduncle in males (13-15 vs. 16), lower pec- (85.2-98.3 % HL vs. 110.6-121% HL), lower anal- toral-fin length (15.5-23.7% SL vs. 23.9-32.6% fin base length (22.1-36.4% SL vs. 40.6-47.2% SL), tip of pectoral fin reaching the 3rd to 4th anal- SL), lower caudal-fin length (16.5-20.9% SL vs. fin ray (vs. 5th to 8th) and lower preopercular neu- 30-36% SL) and smaller number of scales around romasts (19-23 vs. 29-40). Females differ by lower caudal peduncle in males (13-15 vs. 16), smaller body depth (18.3-35.4% SL vs. 35.5-41.8% SL), eye diameter (18.3-28.4% HL vs. 29.0-34.9% lower head depth (83.1-93.9% HL vs. 97.7- HL), higher number of scales in longitudinal series 121.5% HL) and anal-fin base length (12.5-20.1% (29-32 vs. 26-28) and in the transversal series (13- SL vs. 27.2-32.1% SL), lower dorsal-fin base 15 vs. 11-12), and the tip of the pectoral fin reach- length (15.5-27.0% SL vs. 28.0-36.9% SL), lower ing the 3rd to 4th anal-fin ray (vs. 5th to 6th). Fe- eye diameter (21.8-27.2% HL vs. 28.9-33.3% males of A. bagual differ from females of A. nigro- HL), lower number of caudal-fin rays (17-21 vs. fasciatus by a smaller pre pelvic length (28.5-52.4% 23-26), smaller number of horizontal scales around SL vs. 52.9-56.5% SL), lower eye diameter (21.8- the peduncle (14-15 vs. 16) and lower preopercular 27.2% HL vs. 29.1-33.4% HL), higher lower jaw neuromasts (18-20 vs. 29-40).

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Males of A. bagual differ from A. minuano Costa cherti (Loureiro & García, 2004) by the lower anal- & Cheffe, 2001 males by the lower body depth fin base length (22.1-36.4% SL vs. 37.5-44% SL), (23.4-33.8% SL vs. 39.5-51.2% SL), lower head lower caudal-fin length (16.5-20.9% SL vs. 28.5- depth (85.2-98.3% HL vs. 112.3-138% HL), low- 35.5), lower preopercular neuromasts (19-23 vs. er anal-fin base length (22.1-36.4 SL vs. 44.9- 30-37). Females differ by the lower preopercular 53.6% SL), lower caudal-fin length (16.5-20.9% neuromasts (18-20 vs. 30-37), lower body depth SL vs. 28.5-35.5% SL) and smaller number of (18.3-35.4% SL vs. 29.5-36.1% SL) and lower scales around caudal peduncle in males (13-15 vs. anal-fin base length (12.5-20.1% SL vs. 22.3- 16-18), lower dorsal-fin base length (22.1-37.9% 30.1% SL). SL vs. 40.5-48.3% SL), higher number of scales in Males of A. bagual differ from A. viarius by the longitudinal series (29-32 vs. 26-28) and lower lower body depth (23.4-33.8% SL vs. 38.8-44.2% preopercular neuromasts (19-23 vs. 30-37). Fe- SL) and head (85.2-98.3% HL vs. 115.7-12% males of A. bagual differ from females of A. minu- HL), lower anal-fin base length (22.1-36.4% SL ano by lower eye diameter (21.8-27.2% HL vs. vs. 40.7-46.1% SL), lower caudal-fin length (16.5- 29.1-35.1% HL), lower head depth (83.1-93.9% 20.9% SL vs. 26.7-32.6% SL) and smaller number HL vs. 106.1-124% HL) and anal-fin base length of scales around caudal peduncle in males (13-15 (12.5-20.1% SL vs. 28.2-32.1% SL), lower num- vs. 20), lower dorsal-fin base length (22.1-37.9% ber of caudal-fin rays (17-21 vs. 23-26), higher SL vs. 40.0-44.7 % SL), lower head width (55.2- number of scales in longitudinal series (29-32 vs. 64.2% HL vs. 65.6-71.1% HL) and lower preop- 26-28), smaller number of horizontal scales around ercular neuromasts (19-23 vs. 39-40). Females dif- the caudal peduncle (14-15 vs. 16-18) and lower fer by lower body depth (18.3-35.4% SL vs. 34.7- preopercular neuromasts (18-20 vs. 30-37). 41.5% SL), lower head depth (83.1-93.9% HL vs. Austrolebias bagual differs from males of A. rei- 98.2-115.7% HL) and anal-fin base length (12.5-

Fig. 5. Temporary pond located in the Arroio Abranjo floodplain, Rio Camaquã Basin, close to the BR-471 highway, type locality of Austrolebias bagual. Photo by G. M. Wallwitz.

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20.1% SL vs. 23-25.1% SL), lower head width bagual, its low population density and the visible (59.7-68.4% HL vs. 69.0-77.8% HL), lower num- changes in its biotope put the species in an endan- ber of caudal-fin rays (17-21 vs. 22-25), smaller gered situation and highlight the need for dedicat- number of horizontal scales around the caudal pe- ed conservation efforts. In accordance with IUCN duncle (14-15 vs. 20) and lower preopercular neu- criteria, A. bagual is considered a ‘Critically Endan- romasts (18-20 vs. 39-40). gered’ species, being included in the criteria CR Males of A. bagual differ from A. arachan males B2ab (ii, iii). In this sense, the creation of a conser- by the lower body depth (23.4-33.8% SL vs. 25.8- vation unit in the middle course of the Rio Ca- 39.2% SL) and head (85.2-98.3 % HL vs. 104.4- maquã, encompassing the floodplains of the Arroio 114.8% HL), lower anal-fin base length (22.1- Abranjo in the municipality of Encruzilhada do 36.4 SL vs. 42.3-45.9% SL), lower caudal-fin Sul, could ensure the conservation of the species. length (16.5-20.9% SL vs. 27.9-32.9% SL) and smaller number of scales around caudal peduncle ACKNOWLEDGEMENTS in males (13-15 vs. 18-20), lower dorsal-fin base Thanks to Gustavo M. Wallwitz for helping in length (22.1-37.9% SL vs. 41.3-46.4% SL), lower the collecting of fishes and Michel Corrêa for pro- head width (55.2-64.2% HL vs. 66.8-71.3% HL) viding the map of the study area. Thanks to Ricar- and lower preopercular neuromasts (19-23 vs. 25- do Robaldo for providing lab support. We are 31). Females differ by lower snout length (11.5- grateful to Pablo Lehmann and all staff of the Lab- 14.3% HL vs. 14.9-17.6% HL), lower head depth oratório de Ictiologia of Universidade do Vale do (83.1-93.9% HL vs. 97.9-114.4% HL), lower Rio dos Sinos (UNISINOS), especially Lucas anal-fin base length (12.5-20.1% SL vs. 24.9- Schvmambach for clearing and staining specimens 28.7% SL), lower number of caudal-fin rays (17- used in this study. M. V. Volcan thanks CAPES for 21 vs. 22-25), smaller number of horizontal scales the Ph. D. Grant. We are grateful to Dalton around the caudal peduncle (14-15 vs. 18-20) and Nielsen, Stefano Valdesalici and Flávio Lima, for lower preopercular neuromasts (18-20 vs. 25-31). their comments and suggestions which improved Despite having a large catchment area and one of the manuscript. This study was funded by Fun- the largest basins in the southern Rio Grande do dação Grupo Boticário de Proteção à Natureza as Sul, few efforts for ichthyological inventory have part of the project “Peixes Anuais do Pampa”. We been carried out in the Rio Camaquã basin, and thank ICMBio by issuing a collecting license (# thus far, no Austrolebias species have been officially 18334-2). recorded. The occurrence of A. bagual constitutes the first record of the genus in this basin. The area REFERENCES of occurrence of the species is located in the geo- COSTA, W. J. E. M. 1995. Pearl killifishes - the Cynolebiati- morphological unit of the Crystalline Shield of Rio nae: systematics and biogeography of the neotropical annual Grande do Sul in the lowland of the floodplain of fish subfamily. Neptune City, TFH Publications, 128p. themiddle course of Rio Camaquã. This area is a COSTA, W. J. E. M. 2006. The South American annual kil- flat depression surrounded by rugged relief at rela- lifish genus Austrolebias (Teleostei: Cyprinodontiformes: tively high areas (higher than 450 m above sea lev- Rivulidae): phylogenetic relationships, descriptive mor- el), which favours the further isolation and micro- phology and taxonomic revision. Zootaxa, 1213: 1-162. COSTA, W. J. E. M. 2010. Historical biogeography of endemism of A. bagual and suggests a long past iso- Cynolebiasine annual killifishes inferred from dispersal- lation of this area. vicariance analisys. Journal of Biogeography, 37: 1995- Annual fish are the group of vertebrates most en- 2004. dangered in Rio Grande do Sul, comprising about COSTA, W. J. E. M. & CHEFFE, M. M. 2005. Austrolebias 70% of all threatened freshwater fish species (FZB, univentripinnis sp. nov. (Teleostei: Cyprinodontiformes: 2014). 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