Triportheus claudiae, Lopes & Carvalho, 2024

Triportheus claudiae , new species urn:lsid:zoobank.org:act:D56A661B-3783-4698-A76E-40E0C911918D

( Figs. 1–2; Tab. 1)

Triportheus aff. rotundatus . —Mariguela et al., 2016:132 [phylogenetic relationships and biogeography].

Holotype. CITL 400, 102.6 mm SL, bay on Pousada Arara Azul , Pantanal, Corumbá municipality, rio Paraguai basin, Mato Grosso do Sul State, Brazil, 19º19’0.01”S 57º03’14.00”W, 25 Mar 2019, H. Gimenes-Junior, T. T. M. Taveira, F. Severo-Neto & R. Rech. GoogleMaps

Paratypes. Brazil, Mato Grosso do Sul State: CITL 401 , 3 , 94.3–99.7 mm SL, collected with the holotype . CITL 1135 , 3 c&s, 45.3–52.7 mm. LBP 3720, 7, 45.2–69.3 mm SL, Aquidauana Municipality, rio Negro, 19º34’54”S 56º15’16.5”W, 3 Aug 2006, C. Oliveira & L. H. G. Pereira. LBP 3757, 16, 63.4–74.5 mm SL, rio Negro , rio Paraguai basin, Aquidauana Municipality, 19º34’33.7”S 56º14’49”W, 1 Aug 2006, C. Oliveira & L. H. G. Pereira. LBP 11917, 5, 37.9–49.4 mm SL, Corumbá municipality, rio Miranda , 19º34’58.3”S 57º01’18.9”W, 25 Nov 2009, C. Oliveira and team GoogleMaps . Mato Grosso State: MNRJ 21681 View Materials , 82.5 mm SL, Barão de Melgaço, rio Cuiabá, Baía Chacororé , 16 Jan 1978, E. P. Caramaschi & CEPIPAM .

Non-types. The following specimens were not included as type-material due to bad preservation of some morphological structures. Rio Paraguai basin, Brazil, Mato Grosso State: LBP 11916, 3, 55.2–70.7 mm SL. LBP 18627, 3, 68.0– 96.1 mm. Mato Grosso do Sul State: SL. LBP 3557, 62.2 mm SL. LBP 3795, 4, 59.3–81.7 mm SL. LBP 5802, 4, 32.2–35.0 mm SL.

Diagnosis. Triportheus claudiae differs from its congeners by the following combination of characters: two non-elongated scales between the pectoral fin and the ventral keel (vs. one vertically elongated scale between the pectoral fin and the ventral keel in T. albus , T. auritus , T. brachipomus , T. culter (Cope, 1872) , and T. magdalenae ); gill rakers on the lower branch of the first branchial arch, 24–29 (mode = 25, n = 8) (vs. 40–47 in T. trifurcatus (Castelnau, 1855) , 38–48 in T. nematurus , 52–57 in T. guentheri (Garman, 1890) , 35–44 in T. signatus ); predorsal scales regularly disposed, in series, or with maximum two scales out of series (vs. predorsal scales irregularly disposed, not in series, with more than three scales disorganized in T. angulatus , T. rotundatus , T. nematurus , T. guentheri , T. curtus (Garman, 1890) , T. pantanensis , T. orinocensis Malabarba, 2004 , and T. venezuelensis Malabarba, 2004 ); premaxilla teeth in three rows (vs. teeth of premaxilla in two rows in T. curtus and T. pictus (Garman, 1890) ; epipleural bones: 20–21 (vs. 16–17 in T. pantanensis and 22–23 T. signatus ); ventral tubules in the laterossensory canal of the preopercule: 7 (vs. 4–5 in T. nematurus and 5 in T. signatus ).

Description. Morphometric data in Tab. 1. Deep and short body, laterally compressed, with ventral keel by expansion of coracoids. Greatest body depth at vertical through origin of dorsal fin. Slightly convex dorsal profile. Ventral profile convex and expanded between insertion of head and origin of pelvic fin.

Two pairs of nostrils, anterior and posterior opening of similar size; anterior opening circular and posterior opening oval. Terminal mouth, lower jaw largest than the upper jaw. Premaxillary teeth in three rows: outer row with 4(2), 5*(26), or 6(6) tricuspid small teeth; medial row with rarely 2(1) or 3*(33) tricuspid, large teeth and inner row with 5(6), 6(24), or 7*(4) pentacuspid teeth, largest from other teeth on premaxilla. Maxillary bone with 0(12), 1(6), 2*(12), or 3(4) tiny tricuspid teeth. Lower jaw teeth in two rows: outer row with 4(2), 5(27), or 6*(5) large pentacuspid teeth, and inner row with one conical symphysial, large tooth. Gill rakers smaller and wider than branchial filaments; gill rakers on lower branch of first branchial arch: 24(4), 25(8), 26(4), 27*(7), 28(6), or 29(5).

Dorsal fin with ii,9 rays (33); anal fin with iii,26(1), 27*(6), 28(13), 29(9), 30(2) or 31(3) rays, its origin at vertical through last ray of dorsal fin. First branched ray of anal fin larger; pectoral fin with i,10(3), 11*(16) or 12(15) rays, extending more than half length of pelvic fin; pelvic fin with i,6 rays (32); caudal fin with i,9/8,i rays (31), bifurcated margin in juveniles and truncated margin in adults. Middle caudal rays with small extensions in large individuals.

Scales cycloid, large, with approximately same size of orbit. Lateral line complete, curved, its origin dorsally at flank, on supracleithrum and following to ventral region of body after pectoral fin, in third row of scales in vertical of pelvic fin, finishing at medial rays of caudal fin. Canals of lateral line scales with one to three branches; generally, small individuals (less than 50 mm SL) with one single branch and large individuals (more than 50 mm SL) with two or three branches. Perforated scales on lateral line: 31(7), 32(5), 33(7), or 34*(15); six scales above lateral line and two scales below lateral line; two scales on vertical line between origin of pectoral fin and ventral keel; predorsal scales: 9(1), 10(2), 11(6), 12(7), or 13*(2), in regular series; 10(8) or 11(29) scales around caudal peduncle.

Total vertebrae: 35(2) or 36(1); precaudal vertebrae: 17(3); caudal vertebrae: 18(2) or 19(1); epineural bones: 35(2) or 37(1), with first three unbranched; epipleural bones: 20(1) or 21(2), with first epipleural unbranched; epipleural bones from second to 12 th branched in dorsal portion; epipleural bones from 13 th to 21 st unbranched. Upper procurrent rays: eight (1) or nine (2); lower procurrent rays: seven (1) or eight (2).

Coloration in alcohol. Overall ground coloration yellowish silver, darker dorsally. Melanophores on proximal and distal fields of scales, forming five to eight fainted black stripes on flank. Stripes above lateral line generally with grouped melanophores, mainly on third to fifth stripes (from dorsal to ventral region). Remaining stripes with scattered melanophores. One inconspicuous stripe on scales from lateral line, by presence of few scattered melanophores; black stripes on flank converging with diffuse spot at hypural plate and base of caudal fin rays. Melanophores in anterodorsal region of head, from premaxilla to supraoccipital; anterior portion of lower jaw, posterior region of maxilla, antorbital, infraorbitals 4, 5, and 6, supraorbital and all the opercle with scattered melanophores ( Fig. 1). Fins mostly hyaline: dorsal fin with distal tip and interradial membrane black; anal fin, occasionally, with black stripe on scales of base and rays generally hyaline, with scattered melanophores on interradial membrane and grouped melanophores on distal tip; adipose fin with scattered melanophores; caudal fin with melanophores grouped on rays, most evident on medial rays and scattered in interradial membrane. Distal tip of caudal fin black; pectoral fin hyaline, with scattered melanophores on interradial membrane and distal tip; pelvic fin with few scattered melanophores.

Coloration in life. Overall silvery coloration, darker dorsally. Greenish tones on posterior portion of head, in parietal, supraoccipital and opercle. Green metallic chromatophores scattered in scales on flank, between supracleithrum and caudal peduncle most conspicuous on anterior and posterior extremities. Scattered xanthophores on head, mainly in frontal, eyes, infraorbitals 5 and 6 and opercle; scattered xanthophores on scales above the lateral line, most conspicuous in medial portion of body. Scattered melanophores on proximal and distal field of scales, forming five to seven black stripes, inconspicuous, above lateral line. Scattered melanophores in head, conspicuous on lower jaw, maxilla, premaxilla, eyes, antorbital, infraorbitals series, supraorbital, opercle and infraopercle. Fins hyaline, with few scattered melanophores: Dorsal fin hyaline, with rays yellow ground and numerous scattered melanophores. Base of anal fin with diffuse black stripe; anal fin hyaline, with scattered melanophores. Caudal fin hyaline, with yellowish tones on base of interradial membranes and scattered melanophores; medial rays and interradial membrane with scattered melanophores. Adipose fin yellowish, with distal tip hyaline and scattered melanophores. Pectoral fin hyaline, with yellow tones anteriorly and scattered melanophores in all extension. Pelvic fin hyaline, with scattered melanophores ( Fig. 2). Small individuals with high concentration of melanophores in dorsal and pectoral fins, and generally, with one black stripe on base of anal fin; in large individuals, fins hyaline, with scattered melanophores and black stripe on base of anal fin inconspicuous or absent.

Sexual dimorphism and ontogenetic variations. No secondary sexual dimorphism characters were found, including differences in size between females and males. Triportheus claudiae presents differences in caudal fin form and coloration pattern between adults and juveniles. In small individuals (smaller than 50 mm SL) caudal fin bifurcated, without elongated medial rays; in large individuals, caudal fin truncated, with elongated medial rays ( Fig. 3).

Geographical distribution. Triportheus claudiae is known to inhabit the floodplain of the upper rio Paraguai basin ( Fig. 4).

Etymology. The specific name, a genitive form for Claudia, is an homage to Maria Claudia de Souza Lima Malabarba, for highly relevant contributions to the knowledge of the Triportheus species and Neotropical palaeoichthyology. A noun in a genitive case.

Conservation status. Triportheus claudiae is a species with wide distribution in the rio Paraguai and tributaries floodplain, with records in Mato Grosso and Mato Grosso do Sul States, Brazil. Despite the Pantanal wetland has suffered a series of impacts of anthropogenic origin in the last years, such as the conversion of native floodplain fields to exotic pasture, large-scale fires, introduction of allochthonous and exotic fish species and mining, we have no evidence that these activities are effectively affecting this species’ population size, distribution, or biology. Additionally, the known distribution of T. claudiae includes preserved environments, as the Parque Estadual do Rio Negro, Parque Estadual do Encontro das Águas, Parque Nacional do Pantanal Mato-Grossense and several private natural heritage reserves (RPPNs). Using the criteria and categories of International Union for Conservation of Nature (IUCN, 2022), Triportheus claudiae can be classified as Least Concern (LC).

Remarks. Triportheus claudiae was mentioned as T. aff. rotundatus by Mariguela et al. (2016), based on the examination of specimens from the rio Miranda, an important tributary of left margin of the rio Paraguai. This species is morphologically similar to T. rotundatus , it is known to inhabit only the rio Amazonas basin, and is genetically closer to T. nematurus .