Ituglanis amphipotamus Mendonça & Oyakawa & Wosiacki 2018, new species

Ituglanis amphipotamus, new species

(Figures 1, 2A, 3A, 4A, 5, 6 A-C, Table 1)

Ituglanis sp. D. Datovo 2014: 467 (comparative material).

Ituglanis sp. D. Datovo & de Pinna 2014: 3 (comparative material), 11 (remarks on the phylogeny of Ituglanis)

Ituglanis sp. D. Datovo, de Aquino & Langeani 2016: 452 (discussion), 454 (comparative material).

Ituglanis proops. Castro & Wosiacki 2017: 216 (comparative material).

Holotype. MZUSP 69393, 70.3 mm SL; Brazil: São Paulo State, Rio Ribeira de Iguape drainage, Rio Ipiranga, tributary of Rio Juquiá, Fazenda Brasban, mun. Sete Barras; 24°12'19"S 47°53'51"W, 18 May 2001, O. Oyakawa, A. Akama, J. Nolasco & M. de Pinna.

Paratypes. Brazil, São Paulo State: MCP 54010, 4, 44 – 66.6 mm SL, MPEG 37305, 4 (2 c&s), 33.1–63.3 mm SL, collected with holotype. MZUSP 52861, 3, 35.7 –49.0 mm SL, affluent of Rio Juquiá, Ribeira de Iguape drainage, at Fazenda Poço Grande, mun. Juquiá, 24°20'0.0"S 47°38'0.0"W, 12 October 1974, J. Garavello & A. Abe. MZUSP 52862, 1, 61.2 mm SL, Ribeirão Palhau, Ribeira de Iguape drainage, mun. Juquiá, 24°20'0.0"S 47°38'0.0"W, 25 January 1975, J. Garavello & A. Abe. MZUSP 53496, 3, 33.5 – 40.3 mm SL, tributary of Rio Jacupiranga, Ribeira de Iguape drainage, mun. Jacupiranga, 24°39'00"S 47°58'00"W, 19 April 1998, O. Oyakawa, V. Garutti, M. Toledo-Piza & C. Ragazzo. MZUSP 65747, 1, 53.2 mm SL, Rio Preto, Ribeira de Iguape drainage, outside of the limits of Parque Estadual Carlos Botelho, mun. Sete Barras, 24°11'33"S 47°53'25"W, 29 November 2000, O. Oyakawa, A. Akama, J. Nolasco, K. Mautari & A. Paixão. MZUSP 65748, 1, 57.1 mm SL, same data as MZUSP 65747. MZUSP 65749, 3, 45.5 – 57.5 mm SL, same data as MZUSP 65747. MZUSP 65750, 4 (2 c&s), 44.9–60.7 mm SL, Rio Quiolombo, Ribeira de Iguape drainage, mun. Sete Barras, 24°14'14"S 48°33'09"W, 30 November 2000, O. Oyakawa, A. Akama, J. Nolasco & A. Paixão. MZUSP 65751, 2, 45.1 – 63.6 mm SL, Rio Ipiranga, Ribeira de Iguape drainage at Fazenda Brasban, mun. Sete Barras, 24°10'47"S 47°51'27"W, 28 November 2000, O. Oyakawa, A. Akama, J. Nolasco, K. Mautari & A. Paixão. MZUSP 65752, 1, 63.9 mm SL, same data as MZUSP 65751. MZUSP 65753, 2, 66.9 – 76.5 mm SL, same data as MZUSP 65751. MZUSP 84330, 3, 30.9 – 35.3 mm SL, same data as MZUSP 65751. MZUSP 84618, 5, 37.5 – 49.7 mm SL, tributary of Rio Jacupiranga, Ribeira de Iguape drainage, mun. Jacupiranga, 24°37'25"S 48°33'21"W, 29 May 2003, O. Oyakawa. MZUSP 109131, 3, 40.5 – 42.5 mm SL, Ribeirão Itaquaxiara, tributary of Rio Embu-Mirim, Rio Tietê drainage, mun. Itapecerica da Serra, 23°43'56"S 46°48'35"W, 13 April 2010, O. Oyakawa, I. Fichberg & J. Muriel-Cunha. MZUSP 121037, 4, 53.4 – 70.8 mm SL, tributary of Rio Pinheiros, Rio Tietê drainage, at Represa Billings, mun. Mauá, 23°42'44"S 46°27'36"W, 10 May 2014, R. Imoto.

Diagnosis. Ituglanis amphipotamus can be distinguished from all congeners, except I. paraguassuensis Campos-Paiva & Costa, 2007, I. cahyensis Sarmento-Soares, Martins-Pinheiro, Arnada & Chamon 2006, I. parkoi (Miranda Ribeiro 1944) and I. apteryx, by the presence of an anterior fontanel. It can be further distinguished from its congeners by a combination of the following characters: the presence of i,5 pectoral-fin rays, vs. i, 4 in I. apteryx, I. cahyensis I. macunaima, and I. parahybae (Eigenmann 1918); i, 6 in I. agreste, I. guayaberensis (Dahl 1960), I. herberti (Miranda Ribeiro 1940), I. inusitatus, I. laticeps (Kner 1863), I. paraguassuensis Campos-Paiva & Costa 2007, and I. proops; i, 7 in I. bambui, I. epikarsticus, I. mambai, and I. passensis; i, 7–i, 8 in I. boticario and I. ramiroi. The presence of five or six pairs of ribs, vs. two in I. compactus and I. eichhorniarum (Miranda Ribeiro 1912), two to three in I. amazonicus (Steindachner 1882), I. ina Wosiacki, Dutra & Mendonça 2012, I. inusitatus, I. gracilior (Eigenmann 1912), I. metae (Eigenmann 1917), I. nebulosus de Pinna & Keith 2003, and I. parkoi (Miranda Ribeiro 1944). The absence of the antorbital segment of the infraorbital canal (pores i1 and i3 absent), vs. presence in I. agreste, I. boitata, I. compactus, I. paraguassuensis and, I. proops; the pores i1 and i3 are variable in I. australis, but the new species can also be distinguished from I. australis by the color pattern, with rounded blotches similar in size to orbital diameter and sparse dots on dorsal and lateral surface of head and body, decreasing in size towards the caudal fin vs. defined stripes on flank. Ituglanis amphipotamus is further distinguished from I. goya by the color pattern (scattered brown blotches on dorsal and lateral surface of head and body, decreasing in size towards the caudal fin, vs. brown blotches on inner skin layer forming two to five stripes on trunk), by the number of post-Weberian vertebrae (39 vs. 41or 42), and by the absence of the nasal canal (pores s1 and s2 absent,

vs. pore s1 present). The color pattern of Ituglanis amphipotamus is similar to I. boitata and I. proops, the latter occurring in the same drainage of Itugalis amphipotamus, but the new species is readily distinguished from both I. boitata and I. proops by the absence of the nasal canal and the antorbital portion of infraorbital canal (pores i1, i3, s1 and s2 absent, vs. present; figure 2). Ituglanis amphipotamus is further distinguished from I. proops by the size and position of the interopercular patch of odontodes in relation to the opercular patch of odontodes (similar in size, distal end of interopercular patch of odontodes does not reach a transverse line through the anterior margin of opercular patch of odontodes vs. almost the double the size, passing to the middle of the opercular patch of odontodes; figures 3 and 4).

Description. Morphometric data in Table 1; see figures 1–2 for general external aspect. Body elongate, slightly cylindrical on trunk, becoming compressed at caudal peduncle. Head depressed, anterior margin straight; dorsal and ventral profile straight. Eye on anterior half of head, close to posterior nostril; orbit rim not free. Anterior nostril surrounded by tubular flap continuous with base of nasal barbel; posterior nostril larger than anterior nostril, with thin crescent flap along anterior border. Mouth subterminal. Lower lip with lateral fleshy folds continuous with base of rictal barbel. Nasal barbel surpassing pectoral-fin base. Maxilary and rictal barbels surpassing posterior end of trunk canal (pore ll2).

Maxilla slightly longer than premaxilla. Premaxilla with 19–22 conical teeth. Dentary with 24–28 conical teeth. Medial margin of autopalatine with shallow concavity. Anterior fontanel oval, anterior and posterior rims tapered, similar in size to postorbital process of sphenotic+prootic+pterosphenoid. Posterior cranial fontanel reduced to a rounded orifice at posterior half of parieto-supraoccipital. Branchiostegal rays seven (3) or eight (1), fourth, fifth and sixth expanded distally; three (4) attached to cartilage between anterior and posterior ceratohyals; two (3) or three (1) on anterior ceratohyal; two (4) on posterior ceratohyal, lateral most ray free. Opercular patch of odontodes rounded, 18–20 conical odontodes. Interopercular patch of odontodes elongate, 18–28 conical and slightly curved odontodes.

Laterosensory canals with simple tubes ending in single pores. In all examined specimens, the infraorbital line is represented solely by the sphenotic canal (pores i10 and i11) and the supraorbital line is represented solely by the frontal canal (pores s3 and s6). The otic, postotic and scapular canals are continuous to each other (forming pores po1 and po2, located anterodorsal to opercular patch of odontodes) and to a short trunk canal bearing only two pores (ll1 and ll2).

Five pairs of ribs (4), two specimens with six ribs on one side. Post-Weberian vertebrae 39 (4); post-Weberian precaudal vertebrae 12 (2), 13 (1) or 14 (1); post-Weberian caudal vertebrae 25 (1), 26 (1) or 27 (2); post-Weberian abdominal vertebrae seven (2), eight (1) or nine (1); first complete hemal arch on fifth (1), sixth (1) or seventh (2) post-Weberian vertebrae; post-Weberian vertebrae between insertion of first pterygiophore of dorsal and anal fins one (3) or two (1).

Pectoral-fin rays i,5* (36), one c&s specimen with i,4 on left side; first ray twice longer than first branched ray; anterior portion of pectoral-fin base covered by branchial membrane. Pelvic-fin rays i,4* (36), one c&s specimen with i,2 on left side; splint present. Distal margin of pelvic fin surpassing the anus in some specimens. Basipterygium with two anterior processes longer than the main body of bone. Dorsal-fin rays i,7 (2), ii,5 (3), ii,6* (24) or iii,5 (1); in c&s specimens iii p,iii,5 (1), iii,6 (1) or iv p,ii,6 (2); located at posterior half of body. Dorsal-fin pterygiophores seven (1) or eight (3); first pterygiophore posterior to neural spine of 22 nd (2), 23 rd (1) or 24 th (1) post-Weberian vertebra. Anal-fin rays i,5 (10), i,6 (1), ii,4 (13) or ii,5* (6); in c&s specimens iii p,ii,5 (1), iii,4 (2) or iv p,ii,4 (1); located right behind dorsal-fin origin. Anal pterygiophores six (3) or seven (1); first pterygiophore posterior to hemal spine of 24 th (2), 25 th (1) or 27 th (1) post-Weberian vertebra. Caudal-fin rays i,11,i* (33), i,5 (36) on dorsal lobe and i,6 (36) on ventral lobe, one specimen with i,10,i with i, 5 in each lobe. Procurrent caudal-fin rays xvi p (1), xvii p (2) or xviii p (1) on dorsal lobe, distributed across five (1) or six (3) neural spines of posteriormost vertebrae, and xiv p (3) or xvi p (1) on ventral lobe, along five (4) hemal spines of posteriormost vertebrae. Two upper hypural plates present, presumably hypural 3 (ventral) and compound hypural 4+5 (dorsal); single lower hypural plate (compound hypural 1+2) fused to parhypural. Caudal fin rounded.

Coloration in alcohol. Background pale yellow, ventral surface lighter. Rounded blotches similar to orbital diameter, light brown, sparse on dorsal and lateral surface of head and body, decreasing in size towards caudal fin. Scattered small brown blotches on ventral surface of head. Ventral surface from pectoral girdle to pelvic-fin insertion lacking blotches. Area from pelvic fin to caudal-fin with tiny, light brown, rounded blotches. Maxillary, nasal and rictal barbels with small brown rounded blotches. All fins irregularly pigmented with light brown blotches.

Distribution. The new species is known from Rio Ipiranga, Rio Jacupiranga, Rio Juquiá, Rio Preto, Rio Quilombo, Ribeirão Palhau and an unnamed stream, all from Ribeira de Iguape drainage, and from Ribeirão Itaquaxiara, a tributary of Rio Embu-Mirim, and an unnamed tributary of Rio Pinheiros, all from upper Tietê drainage (figure 5).

Etymology. The specific name amphipotamus comes from the Greek amphi meaning double, on both sides, and potamus from the Greek, river, stream, in reference to the presence of the species in two adjacent river basins. A noun in apposition.

Ecological notes. The type locality of Ituglanis amphipotamus is a medium-size river, running over rocky and sandy bottoms at ca. 40 m above sea level. The river is about one meter deep, 20 m wide, clear, oxygenated and fast-flowing (figure 6; a). In all sites where Ituglanis amphipotamus was collected, except for those in the Parque Estadual Carlos Botelho conservation unit, the riparian vegetation was replaced by banana plantation, which is the main economic activity in the Ribeira de Iguape valley. At the type locality, I. amphipotamus occurs syntopically with Acentronichthys leptos Eigenmann & Eigenmann 1889, Astyanax ribeirae Eigenmann 1911, Atlantirivulus santensis (Köhler 1906), Characidium lanei Travassos 1967, Geophagus brasiliensis (Quoy & Gaimard 1824), Gymnotus carapo Linnaeus 1758, Hoplias malabaricus (Bloch 1794), Microglanis cottoides (Boulenger 1891), Mimagoniates microlepis (Steindachner 1877), Pseudotothyris obtusa (Miranda Ribeiro 1911), and Rhamdia quelen (Quoy & Gaimard 1824).

The new species was also collected in the Ribeirão Itaquaxiara, a small tributary of Rio Embu-Mirim at Represa de Guarapiranga, and in a small unnamed tributary of Rio Grande at Represa Billings, both in the Rio Pinheiros drainage. For decades both streams were heavily impacted by deforestation and pollution from several irregular human settlements and industries, which persist. As a result of decades of impacts on the enviroments in the Ribeirão Itaquaxiara only four species were collected with I. amphipotamus: Astyanax fasciatus (Cuvier 1819), Astyanax paranae Eigenmann 1914, Mimagoniates microlepis and Piabina argentea Reinhardt 1867; and in the small tributary to Rio Grande at Represa Billings, Australoheros sp., Hyphessobrycon bifasciatus Ellis 1911, and Piabina argentea. In the years of 2008 and 2009, the Rio Pinheiros basin suffered another great impact during the construction of Governador Mário Covas Beltway that increased soil erosion and the consequent siltation of the aquatic environments (figure 6; b–c).

Conservation status. Ituglanis amphipotamus is known from several localities in the Rio Ribeira de Iguape and only two localities in the upper Rio Tietê. In the Ribeira de Iguape the species also occurs in two protect areas, the Parque Estadual Carlos Botelho and Parque Estadual e Turístico do Alto Ribeira (PETAR) conservation units and, at least in these areas, no threats to the species were detected so far. Unfortunately, the same is not true for the populations of the upper Rio Tietê, where it is known from only two localities (see Ecological notes). Considering that today, apparently, there are no threats that may endanger the species in its entire distribution, we suggest that I. amphipotamus should be classified as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2017).