Triportheus nematurus (Kner, 1858)

Triportheus nematurus (Kner, 1858) View in CoL

( Figs. 5–7; Tab. 2)

Chalcinus nematurus Kner, 1858:163 [original description]. —Kner, 1860:13–15 [more detailed description and type-locality indicated as: “Cujaba, Suaguragua, Caiçara”]. —Garman, 1890:3 [synonym of Chalcinus angulatus angulatus]. —Eigenmann, Eigenmann, 1891:56 [synonym of Chalcinus angulatus]. —Ulrey, 1895:294 [synonym of Chalcinus angulatus]. — Miranda Ribeiro, 1941:162–69 [morphometric data, synonym of Chalcinus angulatus]. — Fowler, 1950:356 [synonym of Triportheus angulatus angulatus].

Chalcinus paranensis Günther, 1874: 454 [description, type-locality: Rio Paraná]. —Garman, 1890:4 [listed]. — Eigenmann, Eigenmann, 1891:56 [listed: río de La Plata system]. —Travassos, 1940:720 [listed and notes about parasitism]. — Miranda Ribeiro, 1941:171 [diagnosis and comments about morphology].

Triportheus paranensis. —Fowler, 1950: 358 [new combination, listed: rios Paraná-Paraguai basin]. —Géry, 1977:343 [listed and key to identification]. —Portugal, 1990:136 [revision and redescription]. — Fernández, Butí, 1996:252 [listed to Argentina]. —Gómez, Chebez, 1996:48 [listed from Misiones, Argentina]. —Malabarba, 1998:76 [phylogenetic relationships]. —Britski et al., 1999:29 [listing and key to identification]. —Lima et al., 2003:58 [listed]. —López et al., 2003:19 [listed from Argentina]. —Menni, 2004:74. —Malabarba, 2004:182 [synonym of Triportheus nematurus]. — Britski, 2007:44 [listed and key to identification].

Triportheus nematurus. —Cope, 1878:692 [listed]. —Fowler, 1906:448 [synonym of Chalcinus angulatus]. — Fowler, 1950:356 [synonym of Triportheus angulatus angulatus]. —Portugal, 1990:166–72 [revalidation and redescription, name erroneously attributed to an undescribed species]. —Malabarba, 1998:76 [phylogenetic relationships]. —Britski et al., 1999:29 [listing and key to identification]. —Lima et al., 2003:158 [listed]. — Malabarba, 2004:182 [redescription, lectotype designation; locality of lectotype: “Cujaba”]. —Britski et al., 2007:44 [listed and key to identification]. —Buckup et al., 2007:44 [listed from Brazil]. —Langeani et al., 2007:185 [listed as an allochthonous species in upper rio Paraná basin]. —Graça, Pavanelli, 2007:75 [listed from the upper rio Paraná floodplain]. —Mirande, 2010:485 [phylogenetic relationships]. —Nakagawa, 2011:44 [comments about distribution, identification and study of cephalic musculature]. —Oliveira et al., 2011:13 [phylogenetic relationships and new propose to Triportheidae]. —Litz, Koerber, 2014:10–11 [listed from Uruguay]. —Mariguela et al., 2016:132 [phylogenetic relationships]. —Ota et al., 2018:54 [listed from upper rio Paraná floodplain]. —Reis et al., 2020:463 [listed from Paraná State, Brazil]. —Lopes et al., 2022:247 [illustrated guide and key to identification]. —Brandão et al., 2022:57 [listed from the lower rio Taquari, Paraná State, Brazil]. —Toledo-Piza et al., 2024:436–37 [list]. — Dagosta et al., 2024:69–70, 81 [list and discussion about it is origin in the upper rio Paraná basin].

Diagnosis. Triportheus nematurus differs from its congeners by the following combination of characters: two non-elongated scales between the insertion of the pectoral fin and the ventral keel (vs. one elongate scale between the origin of the pectoral fin and the ventral keel in T. albus , T. auritus , T. brachipomus , T. culter , and T. magdalenae ); 38–48 (mode = 43, n = 23) gill rakers on the lower branch of the first branchial arch (vs. 29–37 in T. angulatus , 24–32 in T. rotundatus , 52–57 in T. guentheri , 22–24 in T. pictus , 23–28 in T. curtus , 26–32 in T. pantanensis , 24–28 in T. orinocensis , 27–33 in T. venezuelensis and 24–29 in T. claudiae ). It further differs by the number of perforated scales on the lateral line, 33–37 (mode = 34, n = 62) (vs. 30–33 [mean = 32.1] in T. guentheri , 30–32 in T. pictus , 28–32 in T. pantanensis ); irregularly disposed scales on the predorsal line, never in one aligned series (vs. regularly disposed scales of the predorsal line, in one aligned series, in T. signatus , T. trifurcatus , T. pictus , and T. claudiae ); number of scales on the transversal line between the origin of the dorsal fin and the lateral line, six (vs. five in T. trifurcatus , T. guentheri , and T. curtus ); 36–37 epineurals (vs. 34–35 in T. pantanensis ), 21 epipleurals (vs. 16–17 in T. pantanensis , and 22–23 in T. signatus ); number of supraneurals, 9 (vs. 10 in T. pantanensis and 10–11 in T. claudiae ); and 4–5 ventral tubules in the laterosensory canal of the preoperculum (vs. 7 in T. pantanensis and T. claudiae ).

Description. Morphometric and meristic data in Tab. 2. Other characters and color in alcohol in Malabarba (2004). Total vertebrae, 36; precaudal vertebrae, 17. Fifteenth precaudal vertebrae with a hemal arch and canal; caudal vertebrae, 18. Epineurals: 35(2), 36(3) or 37(2), first three unforked; epipleurals 21(5) or 22(2). First epipleural unforked, second to 12 th forked proximally and 13 th to 21 st, unforked. Supraneurals: nine (7). Upper procurrent rays, eight (2) or nine (5); lower procurrent rays, seven (7).

Coloration in life. Overall coloration silvery, darker dorsally than ventrally. Dorsolateral region of body greenish. Grouped melanophores on proximal field of scales, forming one to six black longitudinal fainted stripes on dorsolateral region of body, above lateral line, converging to one single stripe, which continues on medial caudal fin rays. Fins mostly hyaline, with few scattered melanophores; origin of pectoral fin, base of first five pectoral fin rays and distal tip of pectoral fin with scattered melanophores; grouped melanophores only on base of pectoral fin and first unbranched ray. Distal tip of dorsal and anal fin with scattered melanophores. Last rays of anal fin with scattered melanophores in all extension. Caudal fin with vertical inconspicuous bands of scattered melanophores, barely visible without stereomicroscope; medial caudal fin rays black in all extension, by presence of closely grouped melanophores ( Fig. 7). Juveniles with large concentration of grouped melanophores in all fins; in adults, fins hyaline with few scattered melanophores.

Sexual dimorphism and ontogenetic variations. No characteristics of secondary sexual dimorphism were found, including variations of size. Variations in caudal fin form and coloration between large and small individuals. In small individuals, less than

50 mm SL, caudal fin bifurcated, without elongated medial rays; in large individuals,

caudal fin truncated, and medial rays elongated, largest than upper and lower caudal fin rays.

Geographical distribution. Triportheus nematurus is widely distributed in lowlands of Paraná-Paraguai basin ( Fig. 8). Its natural occurrence known is from the rio Paraguai and lower rio Paraná basins. In the upper rio Paraná basin, T. nematurus is recognized as a possible introduced species (Dagosta et al., 2024).

Ecological notes. Triportheus nematurus is a generalist species and occurs in lentic environments, such as ponds, lakes, bays, and impoundments (Polaz et al., 2014; Severo-Neto et al., 2015), and in lotic environments, such as rivers (Súarez et al., 2013; Polaz et al., 2014). When juveniles, they are associated with beds of aquatic macrophytes (Súarez et al., 2013). The species is omnivorous, its diet based mainly on terrestrial insects, algae, zooplankton, and terrestrial plant matter (including seeds and fruit). The species presents a high feeding plasticity, evidenced mainly by the temporal variations of its diet (Novakowski et al., 2008; Lopes et al., 2017). In the Pantanal wetlands, they can act as seed dispersers, due to their frugivorous interaction during the flood season (Yule et al., 2016). There is no information about the reproductive biology of this species.

Remarks. Chalcinus nematurus (= Triportheus nematurus ) Kner, 1858 was described based on three lots (syntypes) with locality not mentioned in the original description. Posteriorly, Kner (1860) mentioned the localities as: “Cujaba, Suaguragua, Caicara”, both in Mato Grosso State, collected by J. Natterer. Chalcinus paranensis (= Triportheus nematurus ) Günther, 1874 was described based on a unique individual that corresponded to the holotype, collected in a locality defined simply as “from the river Parana ” and probably refers to an exemplar sampled in the lower rio Paraná basin. Malabarba (2004) recognized T. nematurus as senior synonym of T. paranensis and designated a lectotype (NMW 69034) and the type-locality was fixed as Cuiabá. In the upper rio Paraná basin, the occurrence of this species was historically attributed to the construction of the Itaipu reservoir in the beginning of the 1980’s, which flooded and consequently eliminated the Sete Quedas waterfalls, the biogeographic divisor between the upper rio Paraná basin and the lower rio Paraná basin (Langeani et al., 2007; Graça, Pavanelli, 2007; Petesse, Petrere, 2012; Ota et al., 2018; Garcia et al., 2018; Pelicice et al., 2018; Jarduli et al., 2019). Dagosta et al. (2024) consider T. nematurus as non-native species in the upper rio Paraná basin, however, recognize that a molecular approach is necessary to investigate its occurrence within both basins.

Material examined. Brazil: Goiás State: upper rio Paraná basin: MCP 47744, 3, 133.5– 168.7 mm SL. NUP 8705, 1, 175.8 mm SL. Mato Grosso State: upper rio Paraguai basin: MCP 15630, 1, 80.6 mm SL. MCP 44032, 2, 130.9– 153.5 mm SL. MZUSP 19825, 1, 125.1 mm SL. MZUSP 20440, 1, 125.4 mm SL. MZUSP 28100, 1, 137.7 mm SL. MZUSP 79140, 1, 80.5 mm SL. NUP 1974, 1, 125.2 mm SL. NUP 2935, 1, 220.0 mm SL. NUP 6954, 2, 124.8– 128.7 mm SL. NUP 6994, 1, 147.7 mm SL. NUP 7056, 2, 81.1–84.0 mm SL. NUP 7100, 2, 72.6–113.0 mm SL. NUP 7595, 2, 72.5–96.9 mm SL. NUP 11492, 1, 137.9 mm SL. UFRGS 13453, 2, 56.1–76.8 mm SL. ZUFMS 3274, 7, 39.1–68.9 mm SL. ZUFMS 3438, 1, 41.8 mm SL. Mato Grosso do Sul State: upper rio Paraguai basin: CPUEMS not catalogued p.18, 3, 31.9–38.2 mm SL. CPUEMS not catalogued p.42, 1, 80.1 mm SL. CPUEMS not catalogued p.47, 1, 102.5 mm SL. CPUEMS not catalogued p.89, 3, 61.1–74.6 mm SL. CPUEMS not catalogued p.90, 1, 81.0 mm SL. CPUEMS not catalogued p.92, 4, 75.8–99.6 mm SL. CPUEMS not catalogued p.99, 6, 60.6–70.1 mm SL. CPUEMS not catalogued p.102, 3, 65.5–80.9 mm SL. CPUEMS not catalogued p.110, 1, 98.5 mm SL. DZSJRP 20143, 2, 97.4 mm SL. MZUSP 19740, 1, 134.8 mm SL. NUP 12548, 1, 95.4 mm SL. NUP 12549, 1, 66.5 mm SL. NUP 14220, 2, 132.6– 138.6 mm SL. NUP 14268, 1, 73.5 mm SL. NUP 19898, 1, 140.7 mm SL. NUP 19978, 1, 149.4 mm SL. UFRGS 17443, 2, 56.1–76.8 mm SL. ZUFMS 814, 1, 89.8 mm SL. ZUFMS 856, 3, 74.0– 135.3 mm SL. ZUFMS 3208, 1, 153.3 mm SL. ZUFMS 3209, 1, 126.6 mm SL. ZUFMS 3259, 4, 117.2– 154.2 mm SL. ZUFMS 3268, 5, 108.3– 146.3 mm SL. ZUFMS 3661, 1, 150.8 mm SL. ZUFMS 3704, 11, 74.6–130.2 mm SL. ZUFMS 4857, 3, 119.1– 125.2 mm SL. ZUFMS, 5031, 1, 81.9 mm SL. ZUFMS 5056, 12, 90.0– 194.3 mm SL. ZUFMS 5184, 1, 75.3 mm SL. ZUFMS 5263, 9 (4 c&s), 37.3–59.8 mm SL. ZUFMS 5447, 1, 50.1 mm SL. ZUFMS 5715, 5, 31.8–143.9 mm SL. ZUFMS 5744, 4, 67.9–82.3 mm SL. ZUFMS 5756, 2, 90.3–93.4 mm SL. ZUFMS 5770, 8, 77.0– 102.6 mm SL. Minas Gerais State: upper rio Paraná basin: MCP 44034, 1, 153.7 mm SL. NUP 16876, 2, 48.24–75.4 mm SL. Paraná State: upper and lower rio Paraná basin: MCP 40735, 2, 142.8– 153.6 mm SL. MCP 40765, 2, 189.36– 192.1 mm SL. MZUSP 19854, 1, 171 mm SL. MZUSP 21086, 1, 187.1 mm SL. MZUSP 37181, 1, 134.3 mm SL. NUP 97, 1, 62.5 mm SL. NUP 516, 1, 180.8 mm SL. NUP 1961, 2, 61.2–62.8 mm SL. NUP 7058, 1, 183.6 mm SL. NUP 7146, 2, 185.6– 211.1 mm SL. São Paulo State: upper rio Paraná basin: DZSJRP 621, 1, 83.4 mm SL. DZSJRP 624, 2, 92.7–97.1 mm SL. DZSJRP 4298, 2, 64.9–89.3 mm SL. DZSJRP 10591, 2, 76.9–95.3 mm SL. DZSJRP 13077, 2, 71.9–93.5 mm SL. DZSJRP 13112, 2, 63.9–100.4 mm SL. DZSJRP 13132, 2, 96.0– 102.8 mm SL. ZUFMS 5362, 3, 145.0– 163.6 mm SL. Paraguay: Alto Paraguay Departament: Río Paraguay basin: MZUSP 54148, 1, 74.4 mm SL; MZUSP 54149, 2, 74.3–87.7 mm SL.