Vitor H. P. Pinheiro1, Carolina B. Machado2, Júlio C. Garavello1, Pedro M. Galetti Jr.3 and Alexandre K. de Oliveira4 
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Abstract
O gênero Proloricaria está amplamente distribuído na drenagem do alto rio Paraná. Sua espécie-tipo, Loricaria prolixa, foi descrita a partir de exemplares da bacia do rio Tietê, e a outra espécie, P. lentiginosa, originalmente descrita como L. prolixa lentiginosa, a partir de exemplares da bacia do rio Grande. As duas espécies são morfologicamente muito semelhantes e desde suas descrições há dúvidas quanto ao reconhecimento e sua validade taxonômica. Neste estudo, a taxonomia integrativa foi aplicada para distinguir e definir as espécies a partir de análises morfológicas de espécimes de coleções e de análises moleculares de espécimes coletados recentemente, assim como dados genéticos publicados. As espécies distinguem-se morfologicamente principalmente pelo padrão de coloração e pela presença de um par de placas pré-dorsais anteriores em P. lentiginosa, que estão ausentes em P. prolixa. As análises moleculares também suportam a validade taxonômica das duas espécies, revelando 3,1% de distância genética interespecífica. As espécies são redescritas e as menções de ambas na literatura, e sua distribuição na bacia do alto rio Paraná, são revisadas. Proloricaria prolixa está distribuída nas bacias dos rios Tietê, Paranapanema, Paraná e Paranaíba, enquanto P. lentiginosa é encontrada nas bacias dos rios Grande e Paranaíba.
Palavras-chave: Alto rio Paraná, Delimitação molecular de espécies, Distribuição, Ostariophysi, Peixes de água doce.
Introduction
The family Loricariidae is endemic to the Neotropical region and is the most species-rich family within the order Siluriformes (Chaves et al.,2023; Fricke et al., 2024; Londoño-Burbano, Britto, 2025). Species of this family primarily inhabit the bottom of riverbeds and are characterized by a body and head covered with dermal plates, and a ventrally positioned mouth equipped with suction cup-shaped lips, enabling attachment to substrates. Despite numerous phylogenetic and taxonomic studies aimed at clarifying the phylogenetic relationships of taxa within Loricariidae, inconsistencies persist regarding the number of subfamilies and the diagnostic characters that define their subgroups (Londoño-Burbano, Reis, 2021).
Loricariinae is the second most diverse subfamily within Loricariidae, currently comprising more than 270 valid species distributed across 30 genera (Fricke et al., 2024). This subfamily is recognized as monophyletic, with its members exhibiting a long depressed caudal peduncle and the absence of adipose-fin (Covain et al., 2016). Nearly half of the Loricariinae were originally described in the genus Loricaria Linnaeus, 1758, and later reassigned to other genera (Thomas, Rapp Py-Daniel, 2008). In a taxonomic revision of Loricaria, Isbrücker (1981) noted that authors from the late 19th century to mid-20th century had adopted a subdivision of Loricaria into several subgenera. Isbrücker regarded these subgenera as valid genera and restricted Loricaria to only 11 species in his revision. Subsequent species descriptions and generic reallocations, following Isbrücker’s revision, resulted in the recognition of 19 valid species (Londoño-Burbano et al., 2020; Fricke et al., 2024).
The genus Proloricaria Isbrücker, 2001, with two valid species (Isbrücker et al., 2001), exemplifies a taxonomic change arising from the review and generic reassignment of Loricaria species. The type-species of the genus is Loricaria prolixa Isbrücker & Nijssen, 1978, and the other, originally described as Loricaria prolixa lentiginosa Isbrücker, 1979, was elevated to species status by Isbrücker (1981). Ferraris (2003) considered both species to belong to Loricaria, but Ferraris (2007) later recognized Proloricaria as a valid genus, encompassing P. prolixa and P. lentiginosa. The original description by Isbrücker (2001) lacked sufficient diagnostic characters to properly distinguish the genus, leading some authors, such as Covain, Fish-Muller (2007), to treat Proloricaria as a junior synonym of Loricaria. However, Covain et al. (2016), based on a molecular phylogeny of the subfamily Loricariinae, upheld Proloricaria a valid genus, belonging to the Loricaria group, but more closely related to Brochiloricaria Isbrücker & Nijssen, 1979 and Paraloricaria Isbrücker, 1979 than to Loricaria.
Specimens of Proloricaria were first mentioned in the literature as Loricaria macrodon (non Kner, 1853) by Miranda Ribeiro (1918) and Fowler (1954). Loricaria macrodon Kner, 1853 belongs to the genus Brochiloricaria, distributed in the Paraguay and La Plata basins, and whose type-species is B. chauliodon Isbrücker, 1978. These genera are morphologically similar and are distinct primarily by the size of the dentary teeth. In Brochiloricaria, both the premaxilla and dentary teeth are long, whereas in Proloricaria,the dentary teeth are approximately half the size of those of the premaxilla(Isbrücker, 1979). In the molecular phylogeny of Covain et al. (2016), these two genera appear as sister taxa within a subgroup of the Loricaria group, which is distributed in the Paraná-Paraguay basin. This clade inhabiting southern South America drainages requires further investigation to better define the morphological characteristics of the genera and to clarify their phylogenetic relationships.
Isbrücker et al. (2001) diagnosed Proloricaria by the reduced plates on the abdomen (vs. completely plated abdomen in Loricaria), in combination with a flat and wide body in the pectoral girdle region. These features, along with the large size (specimens can exceed 450 mm standard length), distinguish both species of Proloricaria from other Loricariinae in the upper Paraná River basin (AKO, pers. obs.).
Morphological distinction between P. prolixa and P lentiginosa is troublesome, evidenced by the original description of P. lentiginosa as a subspecies of P. prolixa. The two species were initially distinguished by their color pattern and the amount and arrangement of the small dermal plates on the abdomen. Proloricaria prolixa has a dark transverse bar in front of eyes through nostrils (Isbrücker, Nijssen, 1978), absent in P. lentiginosa. On the other hand, P. lentiginosa is characterized by dorsal region of the head with numerous small, well-defined dark grayish brown spots, which are absent or ill-defined in P. prolixa (Isbrücker, 1979). The minute plates in the abdomen tend to be more numerous in P. lentiginosa compared to P. prolixa. Our previous observations suggested that color pattern and abdominal plates vary with specimen size in both species.
Proloricaria is widely distributed and endemic to the upper Paraná River basin (Dagosta et al., 2024). The two species were described from specimens collected in rivers of this large system. The type-locality of P. prolixa is the Piracicaba River, a tributary of the Tietê River, and the species has been frequently reported in the main river basins of the upper Paraná drainage (including the Grande, Paranaíba, Tietê and Paranapanema rivers). The type-locality of P. lentiginosa is the Volta Grande reservoir, on the Grande River, and this species has been rarely reported outside the Grande River basin. The imprecision in the morphological definitions of the two species raises doubt regarding identifications and occurrences across different basins of the upper Paraná River system.
In the literature, distinguishing between P. prolixa and P. lentiginosa, as well as the validity of the genus Proloricaria, remains problematic. Inconsistencies in the use of species names across different studies highlight the challenges in distinguishing the two species. In the description of L. prolixa, Isbrücker, Nijssen (1978) emphasized the numerous dots on the head of four specimens from the Grande River, although these specimens were not included in the type-series. Isbrücker (1979) described these specimens as the subspecies L. prolixa lentiginosa. Isbrücker (1980) recognized the specific status of L. lentiginosa, and Isbrücker (1981) stated that it “is closely related to (if not a subspecies or a form of) L. prolixa”. Even after the description of the genus Proloricaria (Isbrücker, 2001), consensus regarding the application of the available specific names for the specimens from different rivers of upper Paraná basin has not been reached. Graça, Pavanelli (2007) noted that the two species are difficult to distinguish, except for the color pattern, and identified specimens from the Paraná River floodplain as L. prolixa. Ota et al. (2018), revisiting the same material from Graça and Pavanelli, maintained the identification as L. prolixa, not recognizing the genus Proloricaria. In faunistic studies by Thereza, Langeani (2019) and Ribeiro et al. (2019) in the Grande River basin, and Froehlich et al. (2017) in the southern Mato Grosso State portion of the upper Paraná River, the two species were identified, as P. prolixa and L. lentiginosa, highlighting the controversial scenario regarding the identification of these species and the generic allocation. Specimens from the Grande River basin were identified as P. prolixa in molecular studies (Pereira et al., 2013; Covain et al., 2016). A review of both species is necessary to solve these issues.
An integrative taxonomic approach, combining morphological and molecular analyses, is useful to test the validity of the two nominal species of Proloricaria and to delineate their distribution. This methodology has been successfully applied to other genera in the family Loricariidae, including Guyanancistrus (Fisch-Muller et al., 2018), Hypostomus (Azevedo et al., 2021), and Loricaria (Londoño-Burbano et al.,2023).
Here, we used integrative taxonomic approach to test whether morphological and molecular distinctions support the validity of the two species of Proloricaria. The two species are morphologically diagnosed and redescribed, and a molecular species delimitation approach is employed with specimens from both Tietê and Grande rivers. Additionally, the occurrences of both species in the upper Paraná basin are reconsidered.
Material and methods
Morphological analyses. Morphological study included specimens from Paraná, Tietê, Grande, Paranapanema and Paranaíba river basins. Institutional abbreviations of the collections are: Departamento de Zoologia da Universidade Estadual Paulista “Júlio de Mesquita Filho”, São José do Rio Preto (DZSJRP), Laboratório de Ictiologia da USP, Ribeirão Preto (LIRP), Laboratório de Ictiologia Sistemática do Departamento de Ecologia e Biologia Evolutiva da Universidade Federal de São Carlos – UFSCar (LISDEBE), Museu de Zoologia da Universidade de São Paulo, São Paulo (MZUSP), and Naturhistorisches Museum, Wien (NMW).
Morphometric and meristic data were obtained from 111 specimens (47 P. lentiginosa and 64 P. prolixa). All measurements and counts were carried out on the left side of the specimens; in cases of damaged features, the right side was used. The morphological analyses encompassed 28 morphometric and 16 meristic variables. Additional features examined included color patterns, the arrangement of dots (punctuations smaller than pupil) or spots (larger circular blotches), and the arrangement of dermal plates and odontodes on the head and body.
Point-to-point measurements taken with digital calipers to the nearest 0.1mm included 26 variables described by Thomas, Rapp Py-Daniel (2008), with addition of anal-fin and dorsal-fin base length. Standard length (SL) is expressed in millimeters (mm) and other measurements as percent of standard or head length (HL).
Plate series counts followed Thomas, Rapp Py-Daniel (2008) and Thomas, Sabaj Pérez (2010), and included: lateral series plates (total and coalesced lateral plates); pre-anal and post-anus lateral and median abdominal plates; and post-anal plates. Counts were also carried out for dorsal, pectoral, ventral, anal and caudal-fin rays; premaxillary and dentary teeth; number of well-developed odontode rows in the parieto-supraoccipital; and number of pre-dorsal anterior plates.
Molecular analyses. For molecular analyses, DNA was extracted from clips of pectoral or pelvic fins. A total of 10 tissue samples were used in the molecular analyses: four samples of P. prolixa collected from the Batalha River (Tietê River basin); and six samples of P. lentiginosa sampled from the Grande River (three topotype specimens) and Mogi-Guaçu River (three specimens), a tributary of the Grande River basin. Additionally, sequences of six specimens of P. lentiginosa from Mogi-Guaçu River were obtained from the BOLD Systems public database (FUPR761-FUPR766). It is noteworthy that these specimens are identified as P. prolixa in BOLD Systems. However, during the study, morphological and molecular data, as well as examination of a photo from specimen LBPV34926, evidenced that these specimens are P. lentiginosa. Thus, the final dataset used in the present study comprised four P. prolixa and 12 P. lentiginosa. Detailed information about the specimens, including taxon, voucher (collection number), collection locality, and BOLD Systems access number, is provided in Tab. 1.
TABLE 1 | List of Proloricaria specimens analyzed in the molecular approach. (*) Sequences obtained in this study.
Taxon | Voucher | Locality | Municipality | Bold system |
Proloricaria lentiginosa | LISDEBE 6345 | Grande River | Miguelópolis | FFTSP010-20* |
Proloricaria lentiginosa | LISDEBE 6345 | Grande River | Miguelópolis | FFTSP011-20* |
Proloricaria lentiginosa | LISDEBE 6345 | Grande River | Miguelópolis | FFTSP012-20* |
Proloricaria lentiginosa | LISDEBE 5782 | Mogi-Guaçu River | Mogi-Guaçu | FFTSP082-24* |
Proloricaria lentiginosa | LISDEBE 5782 | Mogi-Guaçu River | Mogi-Guaçu | FFTSP083-24* |
Proloricaria lentiginosa | LISDEBE 5054 | Mogi-Guaçu River | Pirassununga | FFTSP081-24* |
Proloricaria lentiginosa | LBPV 34923 | Mogi-Guaçu River | Pirassununga | FUPR761-09 |
Proloricaria lentiginosa | LBPV 34924 | Mogi-Guaçu River | Conchal | FUPR762-09 |
Proloricaria lentiginosa | LBPV 34925 | Mogi-Guaçu River | Conchal | FUPR763-09 |
Proloricaria lentiginosa | LBPV 34926 | Mogi-Guaçu River | Conchal | FUPR764-09 |
Proloricaria lentiginosa | LBPV 34927 | Mogi-Guaçu River | Conchal | FUPR765-09 |
Proloricaria lentiginosa | LBPV 34928 | Mogi-Guaçu River | Porto Ferreira | FUPR766-09 |
Proloricaria prolixa | LISDEBE 7826 | Batalha River, affluent of Tietê River | Reginópolis | FTTSP084-24* |
Proloricaria prolixa | LISDEBE 7826 | Batalha River, affluent of Tietê River | Reginópolis | FTTSP085-24* |
Proloricaria prolixa | LISDEBE 7826 | Batalha River, affluent of Tietê River | Reginópolis | FTTSP086-24* |
Proloricaria prolixa | LISDEBE 7826 | Batalha River, affluent of Tietê River | Reginópolis | FTTSP087-24* |
DNA was extracted following the saline protocol outlined by Aljanabi, Martinez (1997). The universal primers designed for fish (COI-FishF1 and COI-FishR1; Ward et al., 2005) were used to amplify 650-pb fragments from 5’ region of COI gene. The polymerase chain reaction (PCR), following Machado et al. (2017), occurred in a final volume of 25 μL containing 16.9 μL of milli-Q water, 2.5 μL Invitrogen 10X PCR buffer (1X), 2.5 μL dNTPs (0.25 mM), 1 μL MgCl2 (2 mM), 0.5 μL of each primer (0.2 μM), 0.1 μL Platinum® Taq polymerase (0.5 unit) and 1μL DNA (50ng/μL). PCR conditions consisted of an initial denaturation at 94ºC for 2 min, followed by 35 cycles of 30s at 94ºC, 45s at 52ºC, 1 min at 72ºC; and ending at an extension temperature of 72ºC for 10 min. After verifying amplification on a 1% agarose gel, all PCR products were purified using the 20% polyethylene glycol protocol (Kusukawa et al., 1990). The fragments were sequenced in both directions (forward and reverse) on ABI3730XL automatic sequencer (Applied Biosystems). The sequences and electropherograms were deposited in the Barcode of Life Data System (BOLD Systems), project Freshwater fish topotypes from São Paulo state – FFTSP code.
Electropherograms were analyzed using Geneious R7 v. 6.1.6 software (Kearse et al., 2012). To check for stop codons, COI amino acid sequences were obtained from MEGA11 (Tamura et al., 2021) using the “vertebrate mitochondrial genetic code”. The average intra- and interspecific distances, based on Kimura 2-Parameters (K2P) algorithm, were calculated using the same software, as well as pairwise distances. The DNA barcoding approach assumes that specimens with a genetic distance greater than a defined threshold belong to distinct species. As there is no universal threshold to be used (Machado et al., 2017), this was obtained from the minimum of a density plot of genetic distances from the present dataset. This threshold, known as the optimal threshold (OT), was calculated from the “localMinima” function that is embedded in the SPIDER package (Brown et al., 2012) on the R v. 4.2.1 (R Development Core Team, 2022). The estimated OT (1.61%) was employed in the jMOTU to define Molecular Operational Taxonomic Units (MOTUs), which represent putative species.
The GMYC (generalized mixed Yule-coalescent) species delimitation analysis using a coalescence approach identifies the MOTUs under the maximum likelihood solution, which determines the transition point between the speciation (interspecific events) and coalescence (intraspecific events) processes on a ultrametric tree (Pons et al., 2006). This tree was constructed using a Bayesian Inference algorithm employed in the BEAST v. 2.6.7 software (Bouckaert et al., 2014) with the following settings: the substitution model, estimated by jModeltest (Posada, 2008), was set to K80; a lognormal relaxed molecular clock model and Yule speciation model as a tree prior. Three independent chains were run for 10 million generations, sampling every 1,000 generations. The convergence of MCMC runs was inspected in Tracer v. 1.5 (Effective sample size > 200; Rambaut et al., 2018). Independent runs were combined using LogCombiner v. 2.6.0 (Bouckaert et al., 2014) with 25% burn-in, and TreeAnnotator (Bouckaert et al., 2014) was used to summarize the information from a sample of trees produced based on maximum clade credibility trees. The GMYC analysis was performed with the SPLITS (SPecies LImits by Threshold Statistics – Monaghan et al., 2009) package in R (R Development Core Team, 2022), using single threshold delimitation under default parameters (interval = c (1,10)).
Results
Molecular diagnosis. The final alignment of the 16 COI gene sequences (four specimens belonging to the P. prolixa and 12 to the P. lentiginosa) had a total length of 600 bp, with 19 variable sites, 18 of which were parsimony informative. All variations were synonymous mutations (no amino acid change). No insertions, deletions or stop codons were observed, evidencing that we used functional COI sequences and not NUMTs (Nuclear Mitochondrial DNA segments). Molecular analyses, based on distance and coalescence methods, support the distinction and recognition of the two species. The average genetic distance (K2P) among specimens of the two species was 3.1%. The average intraspecific distance for P. prolixa was 0.06% (Min = 0% and Max = 0.17%), while for P. lentiginosa it was 0.09% (Min = 0% and Max = 0.18%) (Tab. 2).
TABLE 2 | Pairwise K2P genetic distances (%) among samples of Proloricaria prolixa (1–4) and P. lentiginosa (5–16), based on COI sequences.
| Proloricaria prolixa | Proloricaria lentiginosa | ||||||||||||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | |||
Proloricaria prolixa | Tietê River | 1. FFTSP087-24 |
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2. FFTSP086-24 | 0.17 |
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3. FFTSP085-24 | 0.00 | 0.00 |
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4. FFTSP084-24 | 0.00 | 0.17 | 0.00 |
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Proloricaria lentiginosa | Grande River | 5. FFTSP011-20 | 3.09 | 3.26 | 3.35 | 3.09 |
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6. FFTSP012-20 | 3.09 | 3.26 | 3.35 | 3.9 | 0.00 |
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7. FFTSP010-20 | 3.09 | 3.26 | 3.35 | 3.09 | 0.00 | 0.00 |
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Mogi-Guaçu River | 8. FFTSP081-24 | 2.91 | 3.08 | 3.16 | 2.91 | 0.17 | 0.17 | 0.17 |
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9. FFTSP083-24 | 2.91 | 3.08 | 3.16 | 2.91 | 0.17 | 0.17 | 0.17 | 0.00 |
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10. FFTSP082-24 | 2.91 | 3.08 | 3.16 | 2.91 | 0.17 | 0.17 | 0.17 | 0.00 | 0.00 |
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11. FUPR766 | 2.91 | 3.08 | 3.16 | 2.91 | 0.17 | 0.17 | 0.17 | 0.00 | 0.00 | 0.00 |
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12. FUPR764 | 3.31 | 3.50 | 3.35 | 3.31 | 0.00 | 0.00 | 0.00 | 0.18 | 0.18 | 0.18 | 0.18 |
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13. FUPR763 | 2.91 | 3.08 | 3.16 | 2.91 | 0.17 | 0.17 | 0.17 | 0.00 | 0.00 | 0.00 | 0.0 | 0.18 |
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14. FUPR762 | 3.09 | 3.26 | 3.35 | 3.09 | 0.0 | 0.00 | 0.00 | 0.17 | 0.17 | 0.17 | 0.17 | 0.00 | 0.17 |
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15. FUPR761 | 2.91 | 3.08 | 3.16 | 2.91 | 0.17 | 0.17 | 0.17 | 0.00 | 0.00 | 0.00 | 0.00 | 0.18 | 0.00 | 0.17 |
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16. FUPR765 | 2.91 | 3.08 | 3.16 | 2.91 | 0.17 | 0.17 | 0.17 | 0.00 | 0.00 | 0.00 | 0.00 | 0.18 | 0.00 | 0.17 | 0.00 |
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The single threshold GMYC model using the ultrametric phylogenetic tree generated through BEAST resulted in the identification of two MOTUS, corresponding to P. prolixa and P. lentiginosa, with confidence interval (CI) 2–15 (Fig. 1). The maximum likelihood for the GMYC model (L = 107.091) was significantly superior to the likelihood of the null model (L0 = 98.54065, P = 0.0001).
FIGURE 1| Ultrametric tree based on Bayesian inference algorithm built in the BEAST v. 2.4.7. Both approaches of species delimitation methods, based on distance and coalescence, support the distinction of Proloricaria lentiginosa and P. prolixa species. Black circles in nodes represent posterior probabilities above 0.95.
Proloricaria lentiginosa(Isbrücker, 1979)
(Figs. 2–3)
Loricaria prolixa lentiginosa Isbrücker, 1979:97 (original description, type-locality: Volta Grande Reservoir, Grande River).
Loricaria lentiginosa.―Ferraris, 2003:337 (catalogue of Neotropical freshwater fish). ―Ghazzi, Oyakawa, 2007:89 (catalogue, freshwater fishes of Brazil). ―Perez-Junior, Garavello, 2007:331 (Mogi-Guaçu River basin). ―Meschiatti, Arcifa, 2009:141 (literature compilation). ―Oliveira et al., 2009:493 (Mogi-Guaçu River basin). ―Oliveira et al., 2015:5 (list of species Sapucaí-Mirim River). ―Froehlich et al., 2017:8 (upper Paraná River). ―Thereza, Langeani, 2019:50 (diagnosis; Grande River). ―Ribeiro et al., 2019:138 (Uberaba River).
Loricaria macrodon (nonKner, 1853). ―Miranda-Ribeiro, 1918:718 (part, list of species, Mogi-Guaçu River). ―Fowler, 1954:96 (part, catalogue, Mogi Guaçu River). ―Schubart, 1962 (list of species, Mogi-Guaçu River). ―Schubart, 1964 (list of Loricariidae from Mogi-Guaçu River).
Loricaria prolixa. ―Isbrücker & Nijssen, 1978:189–94 (part; non paratypes; Mogi Guaçu and Grande rivers). ―Meschiatti, Arcifa, 2009:141 (literature compilation). ―Covain et al. (2016):498 (molecular phylogeny, Mogi-Guaçu River).
Proloricaria lentiginosa.―Isbrücker et al., 2001:21 (diagnosis of Proloricaria). ―Isbrücker, 2001:31 (list of Loricariidae species). ―Ferraris, 2007:286 (catalogue of Siluriformes). ―Dagosta et al., 2024:23(geographic distribution).
Proloricaria prolixa. ―Pereira et al.(2013): additional file 1 (DNA barcode, Mogi-Guaçu River). ―Thereza, Langeani, 2019:51 (catalogue, Grande River basin). ―Ribeiro et al., 2019:139 (list of species, Uberaba River).
Diagnosis. Proloricaria lentiginosa is distinguished from P. prolixa by color pattern, with numerous well-defined rounded grayish-brown dots and spots on the dorsal region of head and body, smaller and more numerous on head, greater and less numerous on body (vs. dorsal surface of head with ill-defined or absent dots, a dark transverse bar between the nostrils and the anterior margin of the orbits followed by another clear bar, positioned over the orbits; and body with irregular pigmentation, in P. prolixa). Additionally, P. lentiginosa possesses two small plates anterior to the series of predorsal plates, in contact on each side of parieto-supraoccipital (rarely on just one side, or none) (vs. none, rarely one or two small anterior plates, in P. prolixa) (Fig. 4). The parieto-supraoccipital typically has a single row of well-developed odontodes in P. lentiginosa (vs. one or two rows in P. prolixa). The quantity and arrangement of abdominal plates is highly variable in both species and not useful to distinguish them.
FIGURE 2| Proloricaria lentiginosa, LISDEBE 6345, 384 mm SL, Grande River, downstream Volta Grande Reservoir, State of São Paulo.
FIGURE 3| Dorsal and ventral views of Proloricaria lentiginosa, MZUSP 13188, holotype, 297 mm SL, Volta Grande Reservoir, Grande River. Photographed by Eduardo Baena, available at http://acsi.acnatsci.org/base/index.html.
FIGURE 4| Schematic detail of 1st and 2nd predorsal plates disposition (grey color) in Proloricaria lentiginosa (left) and P. prolixa (right). Arrows indicate the additional pair of plates anterior to pre-dorsal series in P. lentiginosa. CPT – compound-pterotic, PD1 – 1st paired predorsal plates, PD2 – 2nd predorsal plate, PSO – parieto-supraoccipital.
Description.Morphometric data are summarized in Tab. 3. Standard length of specimens examined 128–420 mm. Body elongate, dorsoventrally depressed, widest in cleithrum. Dorsal profile of body slightly convex from tip of snout to dorsal-fin origin. Ventral profile slightly convex, mostly flat. Greatest body depth at dorsal-fin origin. Head triangular in dorsal view, with round snout and slightly convex lateral margins from snout tip to operculum. Head dorsal profile straight and inclined from tip of snout to anterodorsal margin of orbit, slightly inclined to posterior elevated margin of parieto-supraoccipital. Eye small, maximum orbital diameter 10.4–17.0% in HL. Post orbital notch absent.
TABLE 3 | Morphometric and meristic data of Proloricaria lentiginosa and P. prolixa. Proportions expressed as percent of standard length or head length. Meristic data represent number of specimens of each count in parenthesis. H = holotype. *Data from Isbrücker (1978), not included in statistical analysis.
Morphometric | Proloricaria lentiginosa (N = 47) | Proloricaria prolixa (N = 64) | ||||||
H | Range | Mean | SD | H* | Range | Mean | SD | |
Standard length | 297 | 128–420 | 289.5 | – | 295 | 89-415 | 283.3 | – |
Percents of standard length | ||||||||
Head length | 21.3 | 19.8–24.7 | 22.2 | 0.9 | 21.3 | 20.1–25.4 | 22.0 | 0.9 |
Body depth | 10.4 | 7.8–12.7 | 10.1 | 1.1 | 8.2 | 6.8–12.4 | 9.9 | 1.1 |
Predorsal length | 31.0 | 28.2–33.3 | 32.0 | 0.9 | 30.7 | 30.0–36.4 | 32.2 | 1.0 |
Body width at post-cleithral tip | 18.2 | 15.6–20.1 | 18.4 | 0.9 | – | 15.0–20.7 | 18.5 | 1.0 |
Body width at anal spine origin | 17.3 | 13.9–18.6 | 16.7 | 1.2 | 17.9 | 10.7–19.8 | 16.9 | 1.7 |
Thoracic length | 13.8 | 12.8–17.4 | 15.3 | 1.2 | 17.4 | 12.5–18.1 | 15.8 | 1.1 |
Abdominal length | 15.3 | 11.3–24.3 | 16.3 | 1.6 | 17.1 | 13.7–18.4 | 16.4 | 1.0 |
Post-anal length | 48.1 | 41.5–51.3 | 48.0 | 1.7 | 48.7 | 44.7–51.1 | 48.2 | 1.3 |
Percents of head length | ||||||||
Snout length | 57.8 | 54.7–61.3 | 58.2 | 1.4 | 57.2 | 45.1–60.7 | 57.6 | 2.4 |
Interorbital distance | 18.7 | 17.0–21.0 | 18.9 | 1.0 | 17.6 | 17.0–20.6 | 18.7 | 0.8 |
Maximum orbital diameter | 13.3 | 10.4–17.0 | 13.0 | 1.5 | 12.1 | 10.1–18.5 | 12.7 | 1.7 |
Head width | 94.0 | 81.1–100.1 | 92.5 | 4.5 | 93.8 | 75.2–97.7 | 92.3 | 4.1 |
Head depth | 38.9 | 33.5–57.3 | 43.1 | 6.4 | 35.8 | 30.4–54.3 | 42.8 | 5.1 |
Internares width at posterior bony nostrils | 8.9 | 6.5–10.6 | 8.3 | 0.8 | – | 5.6–9.8 | 7.7 | 0.8 |
Left nostril to right orbit at frontal-sphenotic juncture | 18.7 | 13.7–20.2 | 18.9 | 1.2 | – | 16.3–20.3 | 18.6 | 0.8 |
Orbit at frontal-sphenotic juncture to PSO tip | 40.2 | 39.3–44.2 | 41.5 | 1.1 | – | 38.6–44.4 | 41.2 | 1.5 |
Meristic counts | ||||||||
Total lateral plates | 32(1), 33(4), 34(33), 35(9) | 33(4), 34(23), 35(34), 36(3) | ||||||
Fused lateral plates | 12(4), 13(22), 14(15), 15(6) | 11(1), 12(12), 13(30), 14(18), 15(3) | ||||||
Post-anal plates | 19(3), 20(30), 21(14) | 19(8), 20(52), 21(4) | ||||||
Left premaxillary teeth | 1(2), 2(15), 3(26), 4(4) | 1(1), 2(30), 3(25), 4(4), 5(3) | ||||||
Right premaxillary teeth | 1(1), 2(20), 3(22), 4(2), 5(2) | 1(1), 2(22), 3(31), 4(7), 5(2) | ||||||
Left dentary teeth | 4(5), 5(17), 6(18), 7(7) | 3(1), 4(7), 5(22), 6(29), 7(4), 9(1) | ||||||
Right dentary teeth | 4(4), 5(14), 6(21), 7(8) | 3(1), 4(5), 5(26), 6(24), 7(7) | ||||||
Plates bordering laterally parieto-supraoccipital | 2(1), 3(9), 4(36) | 2(53), 3(4), 4(6) | ||||||
Parieto-supraoccipital large odontode rows | 1(38), 2(9) | 1(33), 2(30) | ||||||
Ventral mouth, thin lips with small, thin, simple or bifid barbels. Upper lip barbels longer than lower lip, more numerous, and distributed over entire surface. Rictal barbel long, occasionally reaching gill openings, branched, with simple or bifid secondary barbels similar to those on upper lip. Lower lip broad, with smaller and more dispersed barbels relative to those on upper lip. Posterior edge of lower lip rounded, with shallow median notch; barbels more elongated than others on its surface. Teeth in both maxillae. Each tooth with a small lateral cusp and longer main cusp, with rounded tips. Premaxillary teeth one to four (modally three) on each side; curved towards the inside of mouth. Dentary teeth four to seven (modally six) on each side; less than half the length of premaxillary teeth and shorter cusps.
Body completely covered with dermal plates, except ventral surface of head, portions of thorax and abdomen, around bases of pectoral and ventral fins, and areas lateral and posterior to the anus. Abdomen with small and minute bony plates, partially naked in young specimens. One pair of small plates laterally positioned to the parieto-supraoccipital and anterior to the first pair of predorsal plates (Fig. 4). Crests of odontodes in the posterior portion of parieto-supraoccipital and predorsal plates. Each dorsolateral and lateral plates with one crest of odontodes.
Dorsal-fin rays I,7, with posterior margin straight; reaching the fourth or fifth posterior dorsal plate when adpressed. Pectoral-fin rays I,6, with distal margin curved or slightly convex; the spine, when adpressed, surpassing the half-length of pelvic-fin spine. Pelvic-fin rays I,5, with convex distal margin; spine much longer than the branched rays, surpassing the anal-fin base when adpressed. Anal-fin rays I,5, reaching the fifth or sixtieth postanal plate when adpressed, with distal margin convex. Principal caudal-fin rays I,10,I; posterior margin of fin deeply concave; upper unbranched ray produced into long trailing filament with at least half of standard length (broken in most specimens examined).
Coloration in alcohol. Ground color of dorsal region of the head and body greyish tan to pale yellow. Head with several rounded grayish-brown dots, smaller than pupil and more numerous on snout, greater on posterior part of head. Dark spots (almost size of eye) on dorsum of body (more numerous and conspicuous in pre dorsal region), sometimes irregular or ill-defined. Dark blotches posterior to dorsal fin sometimes longitudinally aligned, forming three to four lines of blotches in specimens with more than 250 mm SL. Dark grey transverse bars on the dorsum of the body conspicuous in small (up to 200 mm SL) specimens, but pale or absent in larger specimens. Ventral regions of head and body whitish to pale yellow.
Dorsal-fin brownish, with dark spots on spine and branched rays arranged in oblique irregular bands. Pectoral-fin dark brownish, with irregular dark spots in spine, branched rays and membranes, forming irregular bands on its entire surface; darker on its proximal portion. Pelvic-fin pale, with dark spots on spine and branched rays. Anal-fin pale, with faint spots on spine, and inconspicuous spots on distal half of the branched rays. Caudal-fin brownish, with dark spots on rays arranged in vertical irregular bands. The same color pattern is observed in living and recently collected specimens, but the dark pigmentation is more conspicuous than in older specimens examined.
Sexual dimorphism. Dissection of seven specimens (LISDEBE 3476, female, 323 mm SL; LISDEBE 4337, two females, 294–351 mm SL; LISDEBE 7883, female, 354 mm SL; LISDEBE 3476, male, 347 mm SL; LISDEBE 6345, male, 420 mm SL; LISDEBE 7883, male, 350 mm SL) revealed some traits previously observed in other members of the Loricariini tribe (Isbrücker, 1981; Thomas, Rapp Py-Daniel, 2008). Adult males have slightly shorter barbels and more numerous and well developed round papilae in the lower lip; dentary teeth tend to be rounded, with main cuspid shorter than those observed in adult females.
Geographical distribution. Proloricaria lentiginosa is distributed in the Grande and Paranaíba river basins, in the states of São Paulo, Minas Gerais and Goiás (Fig. 5). It occurs in small to large riverine habitats with sandy and rocky bottom.
FIGURE 5| Distribution of localities of the examined lots of Proloricaria lentiginosa (red circles) and P. prolixa (blue circles). Stars represent type-localities.
Material examined. All from Brazil. São Paulo: MZUSP 13188, holotype of Loricaria prolixa lentiginosa , 297.0 mm SL; MZUSP 13190, paratype, 261.0 mm SL; MZUSP 13187, paratype, 265.0 mm SL; MZUSP 85885, 2, 166.0–167.0 mm SL; MZUSP 2932, 1, 327.0 mm SL; MZUSP 25694, 2, 190.2–319.0 mm SL; LISDEBE 4337, 5, 294.0–351.0 mm SL; LISDEBE, 4102, 2, 276.0–320.0 mm SL; LISDEBE 6345, 4, 365.0–420.0 mm SL; LISDEBE 5782, 5, 284.0–368.0 mm SL; LISDEBE 7570, 1, 276.0 mm SL; LISDEBE 7883, 2, 350.0–354.0 mm SL; LISDEBE 7885, 3, 228.0–261.0 mm SL; LISDEBE 7887, 1, 228.0 mm SL; LISDEBE 4376, 7, 284.0–369.0 mm SL; LISDEBE 4312, 1, 332.0 mm SL; LISDEBE 5054, 2, 328.0–350.0 mm SL; LISDEBE 7888, 1, 260.0 mm SL; LISDEBE 7889, 1, 339.0 mm SL; LISDEBE 7890, 2, 320.0–330.0 mm SL; DZSJRP 8423, 1, 379.0 mm SL; LIRP 202, 1, 326.0 mm SL; LIRP 15030, 1, 325.0 mm SL; LIRP 14886, 1, 144.0 mm SL. Goiás: DZSJRP 15969, 1, 220.0 mm SL; DZSJRP 16057, 4, 214.0–217.0 mm SL. Minas Gerais: MZUSP 24778, 1, 318.0 mm SL; LISDEBE 5410, 7, 223.0–329.0 mm SL; LISDEBE 5322, 2, 253.0–268.0 mm SL; LISDEBE 5403, 1, 272.0 mm SL; LISDEBE 5222, 1, 236.0 mm SL; LISDEBE 6033, 2, 267.0–302.0 mm SL; DZSJRP 16102, 2, 128.0–132.0 mm SL.
Proloricaria prolixa (Isbrücker & Nijssen, 1978)
(Figs. 6–7)
Loricaria prolixa Isbrücker & Nijssen, 1978:189–94 (part; original description, type-locality: Piracicaba River). ―Ferraris, 2003:337 (catalogue of Neotropical freshwater fish). ―Ghazzi, Oyakawa, 2007:89 (catalogue, freshwater fishes of Brazil). ―Graça, Pavanelli, 2007:120 (catalogue, upper Paraná River basin). ―Langeani et al., 2007:188 (Borá River, Tietê drainage). ―Ota et al., 2018:77 (diagnosis, upper Paraná River floodplain).
Loricaria macrodon (non Kner, 1853). ―Miranda-Ribeiro, 1918:718 (part, list, Piracicaba River). ―Fowler, 1954:96 (part, catalogue, Piracicaba River).
Proloricaria prolixa.―Isbrücker et al., 2001:21 (diagnosis of Proloricaria). ―Isbrücker, 2001:31 (list of Loricariidae species). ―Ferraris, 2007:286 (catalogue of Siluriformes). ―Froehlich et al., 2017:8 (checklist, Mato Grosso do Sul). ―Jarduli et al., 2020:11 (literature revision, Panapanema River). ―Dagosta et al., 2024:23(geographic distribution).
Diagnosis. Proloricaria prolixa is distinguished from its congener by having a dark transverse bar between the nostrils and the anterior margin of the orbits followed by another clear bar, positioned over the orbits (vs. dark transverse bar absent in P. lentiginosa) (Fig. 8); none, rarely one or two, pair of plates anterior to the series of predorsal paired plates (vs. pair of anterior plates, one on each side (rarely in just one side, or none), in P. lentiginosa). Parieto-supraoccipital normally with one or two rows of well-developed odontodes (vs. one row in P. lentiginosa).
FIGURE 6| Proloricaria prolixa, LISDEBE 7710, 313 mm SL, Ourinhos Reservoir, Paranapanema River.
FIGURE 7| Dorsal and ventral views of Proloricaria prolixa, NMW 45091, holotype, 294 mm SL, Piracicaba River, Tietê River basin. Photographed by Mark H. Sabaj and Kyle Luckenbill.
FIGURE 8| Color pattern of head in Proloricaria lentiginosa (left), LISDEBE 4376, 322 mm SL, Sapucaí-Mirim River, Grande River basin, and P. prolixa (right), LISDEBE 7826, 350 mm SL, Batalha River, Tietê River basin.
Description. Morphometric data summarized in Tab. 3. Standard length of specimens examined 44-415 mm. Body elongate, dorsoventrally depressed, widest in cleithrum. Ventral profile slightly convex, mostly flat. Greatest body depth at dorsal-fin origin. Head triangular in dorsal view, with round snout and slightly convex lateral margins from snout tip to operculum. Head dorsal profile straight and inclined from tip of snout to anterodorsal margin of orbit, and slightly inclined to posterior elevated margin of parieto-supraoccipital. Eye small, maximum orbital diameter 10.1–18.5% in HL. Post orbital notch absent.
Ventral mouth, thin lips with small, thin, simple or bifid barbels. Upper lip barbels longer than lower lip, more numerous, and distributed over entire surface. Rictal barbel long, occasionally reaching the gill openings, branched, with simple or bifid secondary barbels similar to those on upper lip. Lower lip broad, with smaller and more dispersed barbels relative to those on the upper lip. Posterior edge of lower lip rounded, with shallow median notch; barbels more elongated than others on its surface. Teeth in both maxillae. Each tooth with a small lateral cusp and longer main cusp, with rounded tips. Premaxillary teeth one to five (modally three) on each side, curved towards the inside of the mouth. Dentary teeth three to nine (modally six) on each side; less than half the length of premaxillary teeth and shorter cusps.
Body completely covered with dermal plates, except the ventral surface of the head, portions of thorax and abdomen, around bases of pectoral and ventral fins, and areas lateral and posterior to anus. Abdomen with small and minute bony plates, partially naked in young specimens. Parieto-supraoccipital and predorsal plates with odontode crests. Each dorsolateral and lateral plates with one crest of odontodes.
Dorsal-fin fin rays I,7, with posterior margin straight; reaching the fourth or fifth posterior dorsal plate when adpressed. Pectoral-fin rays I,6, with distal margin curved or slightly convex; the spine, when adpressed, surpassing the half-length of pelvic-fin spine. Pelvic-fin rays I,5, with convex distal margin, spine much longer than branched rays, surpassing the anal-fin base when adpressed. Anal-fin rays I,5, reaching the fifth sixtieth postanal plate when adpressed, with distal margin convex. Principal caudal-fin rays I,10,I; posterior margin of fin deeply concave; upper unbranched ray produced into a long trailing filament with at least half of standard length (broken in most specimens examined).
Coloration in alcohol. Ground color of dorsum of the head and body greyish tan to pale yellow. Ventral region of head and body whitish to pale yellow. Several rounded grayish-brown dots, generally much small, well defined, and relatively concentrated on the back of the head, but inconspicuous or absent in some specimens. Tiny dots can be distributed both anteriorly and posteriorly on the back of the head, those in the posterior part of head and anterior part of body larger. Head with a dark transverse bar passing through the nostrils, reaching the anterior margin of the orbits, usually followed by another light transverse bar passing through the orbits. Dorsum of body with larger, poorly defined, and less concentrated blotches relative to those on head, with an irregular distribution, sometimes forming a zigzag longitudinal row on each side of the dorsal surface of the body, in the region between the series of dorsal and lateral plates. Conspicuous dark grey transverse bars on dorsum of the body in small (up to 200 mm SL) specimens, pale or absent on greater specimens.
Dorsal-fin brownish, with dark spots on spine and branched rays arranged in oblique irregular bands. Pectoral-fin brownish, darker than other fins, with irregular dark spots in spine, branched rays and membranes, forming irregular bands on its entire surface. Pelvic-fin pale, with dark spots on spine and branched rays. Anal-fin pale, with faint spots on spine, and inconspicuous spots on branched rays. Caudal-fin brownish, with dark spots on rays arranged in three to four vertical irregular bands. The same color pattern is observed in living and recently collected specimens, but the dark pigmentation is more conspicuous than in older specimens.
Sexual dimorphism. Dissection of seven specimens (LISDEBE 7826, three females, 309–322 mm SL; LISDEBE 7709, female, 346 mm SL; LISDEBE 7826, male, 317 mm SL; LISDEBE 7709, male, 315 mm SL; and LISDEBE 7710, male, 331 mm SL) revealed sexual dimorphic traits similar to those observed in P. lentiginosa.
Geographical distribution. Proloricaria prolixa is widely distributed in the upper Paraná River basin (except in the Grande River basin), in states of Goiás, Minas Gerais, Mato Grosso do Sul, Paraná and São Paulo (Fig. 5). It occurs in small to large riverine habitats with sandy and rocky bottom.
Material examined. All from Brazil. Goiás: LIRP 8377, 4, 169.0–259.0 mm SL; LIRP 7299, 1, 228.0 mm SL; LIRP 6942, 1, 159.0 mm SL; LIRP 6937, 1, 213.0 mm SL; LIRP 6635, 1, 225.0 mm SL. Paraná: MZUSP 13394, paratype, 343.0 mm SL; MZUSP 21650, 4, 273.0–409.0 mm SL; LIRP 7545, 4, 269.0–352.0 mm SL. São Paulo: MZUSP 13186, paratype, 230.0 mm SL; MZUSP 333, paratype, 303.0 mm SL; MZUSP 3104, 1, 209.0 mm SL; MZUSP 3243, 1, 363.0 mm SL; MZUSP 22238, 1, 346.0 mm SL; MZUSP 23071, 16, 85.0–341.0 mm SL; MZUSP 87134, 1, 104.8 mm SL; MZUSP 413, 1, 277.0 mm SL; MZUSP 24436, 2, 67.5–326.0 mm SL; MZUSP 37986, 3, 218.0–364.0 mm SL; MZUSP 24380, 2, 327.0–364.0 mm SL; LISDEBE 7657, 3, 271.0–315.0 mm SL; LISDEBE 6071, 1, 180.0 mm SL; LISDEBE 4409, 1, 273.0 mm SL; LISDEBE 4485, 1, 224.0 mm SL; LISDEBE 3464, 1, 267.0 mm SL; LISDEBE 3463, 1, 274.0 mm SL; LISDEBE 7709, 4, 297.0–400.0 mm SL; LISDEBE 7710, 2, 313.0–330.0 mm SL; LISDEBE 4408, 5, 219.0–265.0 mm SL; LISDEBE 4473, 4, 206.0–305.0 mm SL; LISDEBE 7891, 6, 321.0–360.0 mm SL; LISDEBE 7892, 1, 415.0 mm SL; LISDEBE 7826, 12, 174.0–350.0 mm SL; DZSJRP 6312, 2, 105.0–116.0 mm SL; DZSJRP 21342, 2, 233.0–289.0 mm SL; DZSJRP 5388, 1, 44.0 mm SL; LIRP 7569, 2, 257.0–264.0 mm SL.
Discussion
Morphological and molecular analyses corroborated the hypothesis that P. prolixa and P. lentiginosa are distinct species. These species were originally distinguished by color pattern and the quantity and arrangement of abdominal bone plates (Isbrücker, Nijssen, 1978; Isbrücker, 1979), though both characters exhibit variability, complicating species identification. In this study, two additional diagnostic characters were identified: the presence of anterior plates in the predorsal series, and the number of well-developed odontode rows in the parieto-supraoccipital. The additional pair of predorsal plates and a single row of odontodes are predominant in P. lentiginosa, while P. prolixa typically lacks the additional pair of predorsal plates but may possess one or two rows of odontodes in the parieto-supraoccipital. These new characters, combined with the diagnostic traits originally outlined by Isbrücker, Nijssen (1978) and Isbrücker (1981), are expected to simplify the morphological differentiation of the two species.
Color pattern is an important distinguishing feature, but some considerations are necessary. Proloricaria lentiginosa was described as having numerous, small, well-defined dark grayish-brown dots on the dorsal region of the head, absent in P. prolixa; and the dorsal region of the body with large spots and poorly defined dark bars, also containing irregular dots and blotches. Specimens of P. prolixa may have small dark punctuations or dots on snout and head, but the characteristic dark transverse bar above nostrils and anterior to eyes sets it apart. Dorsum of body in P. prolixa usually has fused spots distributed between the series of dorsal and mid-dorsal plates, forming a zigzag longitudinal stripe on the division between these series of plates along the body. This longitudinal line can appear both anteriorly and posteriorly on the body, interrupted or not. In contrast, such a pattern is less apparent in P. lentiginosa, in which the distribution of well-defined spots may be irregular or aligned longitudinally on the body. This color pattern had previously been raised in Isbrücker, Nijssen (1978) in the description of L. prolixa, where they briefly pointed out the occurrence of rounded grayish brown spots on the dorsum, which tend to be arranged in a row on each side. Dark transverse bars in loricariids with dark dots color pattern are widely documented. In both species transverse bars are more conspicuous to smaller individuals and tend to fade with age, though large specimens may still exhibit such transversal bars.
Original descriptions of Proloricaria species suggested plates in abdominal region as diagnostic characters. Proloricaria lentiginosa tends to have more numerous and smaller plates compared to P. prolixa, but the size and number of these plates vary with body size in both species and intraspecific variation in the abdominal plate arrangement was observed even between syntopic specimens of the same size. Therefore, the arrangement of abdominal plates is not a reliable characteristic for distinguishing the two species.
Molecular analyses based on distance and coalescence also support the validity of both species. The average genetic distance between P. lentiginosa and P. prolixa specimens was 3.11%, while average intraspecific distance was 0.09% and 0.06%, respectively, evidencing low genetic variation within the groups of individuals analyzed and, chiefly, that the interspecific genetic distance exceeded (more than 30 times) the average of intraspecific genetic distances. This is in accordance with the DNA barcoding principle that interspecific divergence must be sufficiently greater than intraspecific divergence (Bingpeng et al., 2018; Jamdade et al., 2021). Interspecific genetic distance value obtained is even higher than the optimal threshold estimated from our data set (1.61%) and the thresholds commonly adopted to distinguish fish species using COI gene, which generally vary between 1 and 2% (Wang et al., 2020).
The four sequences of P. prolixa analyzed in this study were obtained from syntopic specimens collected in the Tietê River basin (the same river basin of type-locality). Sequences of P. lentiginosa were obtained in the Grande River basin, with some samples collected downstream the Volta Grande Reservoir, an area near the species’ type-locality. The BOLD sequences of some specimens from Mogi-Guaçu River, previously identified as P. prolixa in DNA barcoding (Pereira et al., 2013) and molecular phylogenetic (Covain et al., 2016) studies, clustered with P. lentiginosa, further corroborating the absence of P. prolixa in the Grande River basin. Application of the two specific names and, posteriorly, generic allocation of the species have been problematic for specimens of Proloricaria in upper Paraná River basin, as evidenced by the list of synonyms here provided.
The genus Proloricaria is endemic and widely distributed in the “Lowlands of the upper rio Paraná” bioregion defined by Dagosta et al. (2024). Despite its wide distribution in this region, the distribution data suggest that P. prolixa and P. lentiginosa exhibit significant spatial segregation. Both species are present in the Paranaíba River, but P. prolixa is commonly found in the Tietê, Paranapanema, Paraná and its right bank tributaries, but not in the Grande River basin. Proloricaria lentiginosa is seemly restricted to Grande and Paranaíba drainages. This intriguing distributional pattern may be associated to the complex drainage scenario in the upper Paraná basin, where great waterfalls historically served as natural barriers to fish populations and species. We agree with Dagosta et al. (2024) affirmation that “the role of various waterfalls, which are now submerged by hydroelectric reservoirs, to the biogeography of upper rio Paraná basin fishes may never be adequately understood”. The observed distribution pattern is probably due to this complex biogeography, where the natural barriers hinder the fish movement along the lowland basin of upper Paraná.
Since Isbrücker’s original descriptions, the names of both species have been inadvertently used in the literature. Integrative taxonomy has provided sufficient evidence to distinguish the two species of Proloricaria, clarifying previous controversies about their identification and validity. Correct identification of the specimens housed in collections has revealed the previously undetected spatial segregation of the two species. This taxonomic resolution, and the identified distribution patterns, may facilitate the species identification in future studies and may have implications for conservation, as each species inhabits distinct and environmentally threatened sections of the upper Paraná River basin.
Acknowledgments
We thank Osvaldo T. Oyakawa (MZUSP), André Esguícero and Flávio Bockmann (LIRP-USP), and Francisco Langeani (DZSJRP-UNESP) for their assistance during visits and loan of specimens from collections under their care. Anja Palandacic (NMW) kindly provided photos of the holotype of Loricaria prolixa taken by Mark Sabaj and Kyle Luckenbill (ANSP). Claudio Oliveira and Jefferson Crispim-Rodrigues (LBP-UNESP) provided a photo of LBPV34926 specimen, from Mogi-Guaçu, allowing its identification as L. lentiginosa. Maria E. Bichuette (UFSCar), Reinaldo J. Castro (UFSCar), Roberto Reis (PUCRS), Lucia Rapp Py-Daniel (INPA), and an anonymous reviewer provided valuable comments to the manuscript. VHPP received a grant from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, process 2021/06334–4). CBM thanks Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES, Finance Code 001) and Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica (CONCYTEC) and the Programa Nacional de Investigación Científica y Estudios Avanzados (PROCIENCIA) within the framework of the E033-2023-01-BM “Alianzas Interinstitucionales para Programas de Doctorado” contest, grant number (PE501084299-2023). PMGJ thanks Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, 303524/2019–7). This study was partially supported by FAPESP (processes 2011/50213–5 and 2018/4388–7).
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Authors
Vitor H. P. Pinheiro1, Carolina B. Machado2, Júlio C. Garavello1, Pedro M. Galetti Jr.3 and Alexandre K. de Oliveira4
[1] Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Carlos, Rodovia Washington Luiz, km 235, Caixa Postal 676, 13565-905 São Carlos, SP, Brazil. (VHPP) vitor.palomo@outlook.com, (JCG) garavelo@ufscar.br.
[2] Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos, Lima, Peru. (CBM) carolbioms@gmail.com.
[3] Departamento de Genética e Evolução, Universidade Federal de São Carlos, Rodovia Washington Luiz, km 235, Caixa Postal 676, 13565-905 São Carlos, SP, Brazil. (PMG) pmgaletti@ufscar.br.
[4] Departamento de Ciências Ambientais, Universidade Federal de São Carlos, Rodovia Washington Luiz, km 235, Caixa Postal 676, 13565-905 São Carlos, SP, Brazil. (AKO) pako@ufscar.br (corresponding author)
Authors’ Contribution 
Vitor H. P. Pinheiro: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Validation, Writing-original draft.
Carolina B. Machado: Data curation, Formal analysis, Investigation, Methodology, Validation, Writing-original draft.
Júlio C. Garavello: Data curation, Formal analysis, Funding acquisition, Investigation, Supervision, Validation, Writing-original draft.
Pedro M. Galetti Jr.: Funding acquisition, Investigation, Methodology, Supervision, Validation, Visualization, Writing-original draft.
Alexandre K. de Oliveira: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Writing-review and editing.
Ethical Statement
Sample collections were authorized by SISBIO (license number 57178–4).
Competing Interests
The author declares no competing interests.
How to cite this article
Pinheiro VHP, Machado CB, Garavello JC, Galetti Jr. PM, Oliveira AK. Integrative taxonomy elucidates the species of Proloricaria (Siluriformes: Loricariidae). Neotrop Ichthyol. 2025; 23(2):e240106. https://doi.org/10.1590/1982-0224-2024-0106
Copyright
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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© 2025 The Authors.
Diversity and Distributions Published by SBI
Accepted March 26, 2025
Submitted October 22, 2024
Epub August 04, 2025