Trichomycterus alternatus, (EIGENMANN, 1917)

Reis, Vinícius & Pinna, Mário De, 2023, Diversity and systematics of Trichomycterus Valenciennes 1832 (Siluriformes: Trichomycteridae) in the Rio Doce Basin: iterating DNA, phylogeny and classical taxonomy, Zoological Journal of the Linnean Society 197, pp. 344-441 : 357-367

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Trichomycterus alternatus
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TRICHOMYCTERUS ALTERNATUS (EIGENMANN, 1917) View in CoL

( FIGS 2–4)

Pygidium alternatum Eigenmann, 1917: 700 View in CoL [type locality: Rio Doce , Brazil, holotype: FMNH 58082 (exCM 7079), paratypes: CAS 64575 (4), FMNH 58083 (62)]; Henn, 1928: 79 (type catalogue); Gosline, 1945: 60 (authorship mistakenly cited as Eigenmann, 1918); Ibarra & Stewart, 1987: 72 (type catalogue); Ferraris, 2007: 414 (checklist).

Trichomycterus alternatum View in CoL ; Burgess, 1989: 321 (list).

Trichomycterus alternatus View in CoL ; Costa, 1992: 104 (comparisons); Bizerril, 1994: 623 (list); Costa & Bockmann, 1994: 717 (comparative material); Miquelarena & Fernández, 2000: 44 (list); de Pinna & Wosiacki, 2003: 279 (checklist); Wosiacki & Garavello, 2004: 5 (list); Triques & Vono, 2004: 170 (comparisons); Bockmann & Sazima 2004: 71 (comparisons); Bockmann et al., 2004: 227 (citation); Alencar & Costa, 2004: 3 (comparisons); Wosiacki, 2005: 51 (comparisons); Wosiacki & Oyakawa, 2005: 470 (comparisons); Ingenito & Buckup, 2007: 1177 (biogeography); Lima et al., 2008: 315 (comparisons); Barbosa & Costa, 2010: 120 (comparisons); Sarmento-Soares et al., 2011: 262 (comparisons); Roldi et al., 2011: 2 (comparisons); Barbosa & Costa, 2011: 308 (comparisons); Barbosa & Costa, 2012: 155 (comparisons); Barbosa, 2013: 274 (comparisons); DoNascimiento et al., 2014a: 709 (comparative material); García-Melo et al., 2016: 238 (comparisons); Ochoa et al., 2017: 75 (relationships, molecular data); Sales et al., 2018: 4 (comparisons); Reis & de Pinna, 2019: 1 (type specimen description, disambiguation of type locality, comparisons); Reis et al., 2019: 12 (comparisons); Donin et al., 2020: 1 (discussion); Reis et al., 2020: 3 (comparisons); DoNascimiento & Prada-Pedreros, 2020: 978 (discussion); Costa et al., 2020: 2924 (discussion); Fernandez et al., 2021: 5 (citation); Ochoa et al., 2020: 3 (discussion on relationship); Lima et al., 2021: 1 (biogeography).

Pygidium travassosi Miranda Ribeiro, 1949: 145 View in CoL , fig. 2 (original description); Miranda Ribeiro, 1954: 12 (type catalogue); Ferraris, 2007: 414 (type catalogue).

Trichomycterus travassosi (Miranda Ribeiro, 1949) View in CoL ; Bizerril, 1994: 623 (taxonomic change); de Pinna & Wosiacki, 2003: 279 (synonym of T. alternatus View in CoL ); Bockmann et al., 2004: 227 (comparison); Barbosa & Costa, 2008: 184 (comparison); Lima et al., 2008: 316 (citation); Barbosa & Costa, 2010: 121 (comparison); Barbosa & Costa, 2011: 308 (comparison); Barbosa & Costa, 2012: 79 (comparison); Reis & de Pinna, 2019: 100 (citation); Costa et al., 2020: 2924 (discussion); DoNascimiento& Prada-Pedreros,2020:978 (discussion).

Trichomycterus longibarbatus Costa, 1992: 104 View in CoL (original description); Ferraris 2007: 420 (type catalogue); Bizerril, 1994: 623 (citation); Burgess & Finley, 1996: 168 (atlas); de Pinna & Wosiacki, 2003: 282 (checklist); Bockmann et al., 2004: 227 (comparison), Alencar & Costa, 2004: 3 (comparison); Barbosa & Costa, 2010: 121 (comparison); Rizzato et al., 2011: 485 (comparison); Barbosa & Costa, 2011: 308 (comparison); Barbosa & Costa, 2012: 156 (comparison); Bichuette & Rizzato, 2012: 52 (comparison), Barbosa, 2013: 274 (comparison); Reis & de Pinna, 2019: 100 (citation); Costa et al., 2020: 2924 (discussion); DoNascimiento & Prada-Pedreros, 2020: 978 (discussion).

Trichomycterus auroguttatus Costa, 1992:105 View in CoL , fig. 6 (original description); Ferraris 2007: 420 (type catalogue); Bizerril, 1994: 623 (citation); Burgess & Finley, 1996: 168 (atlas); de Pinna & Wosiacki, 2003: 282 (checklist); Bockmann et al., 2004: 227 (comparison); Alencar & Costa, 2004: 3 (comparison); Barbosa & Costa, 2010: 121 (comparison); Barbosa & Costa, 2011: 308 (comparison); Barbosa & Costa, 2012: 81 (comparison); Reis & de Pinna, 2019: 100 (citation); Costa et al., 2020: 2924 (discussion); DoNascimiento & Prada-Pedreros, 2020: 978 (discussion).

Diagnosis: Trichomycterus alternatus is the most complex taxon to diagnose among those treated in this work. While clearly distinct from all other valid congeners in the Rio Doce Basin , its reported presence outside the basin and the existence of numerous names of uncertain status applied to poorly-known similar forms in surrounding basins (e.g. T. caudofasciatus , Trichomycterus gasparinii Barbosa, 2013 , Trichomycterus jequitinhonhae Triques & Vono, 2004 , Trichomycterus landinga Triques & Vono, 2004 , Trichomycterus mimosensis Barbosa, 2013 , Trichomycterus nigroauratus Barbosa & Costa, 2008 , Trichomycterus pantherinus Alencar & Costa, 2004 , Trichomycterus puriventris Barbosa & Costa, 2012 ; see Discussion) make any diagnosis unavoidably dependent on additional data from those nominal species. Still, T. alternatus is the oldest available name in that assemblage and it has priority over these other names in case they are found to be synonyms. The combination of the following traits distinguishes T. alternatus from congeners (excepting probable junior synonyms mentioned above): (1) colour pattern of body consisting of four rows of large maculae on (one row mid-dorsal, other three rows on flanks and sides), often disguised by variable fusions and anastomoses, forming patterns ranging from spotted to nebulous, sometimes with a lateral stripe; (2) I + 7 pectoral-fin rays (vs. I + 5, I + 6 or I + 8); (3) two lateral-line pores (vs. three); (4) subtruncate to truncate caudal fin (vs. round or concave); (5) dorsal-fin rays II + 7 (vs. II + 8 or more). Among congeners in south-eastern South America, character 1 distinguishes T. alternatus from T. barrocus and Trichomycterus itatiayae Miranda Ribeiro, 1906 , from all taxa in the T. brasiliensis and T. reinhardti species complex ( Barbosa & Costa, 2010; Costa, 2021; Costa & Katz, 2021), from the species that exhibit the T. nigricans colour pattern ( Reis et al., 2020), from Trichomycterus caipora Lima, Lazzarotto & Costa 2008 , T. aff. caipora , Trichomycterus giganteus Lima & Costa, 2004 , T. illuvies , Trichomycterus itacambirussu Triques & Vono, 2004 and Trichomycterus lauryi Donin, Ferrer & Carvalho, 2020 ; character 2 distinguishes T. alternatus from the T. brasiliensis and T. reinhardti species complex ( Barbosa & Costa, 2010; Costa, 2021; Costa & Katz, 2021), plus Trichomycterus trefauti Wosiacki, 2004 (all preceding with I + 6 or fewer), T. astromycterus , T. caipora , T. giganteus , T. immaculatus , T. lauryi , T.nigricans and T.tantalus (with I + 8 or more); character 3 distinguishes T. alternatus from T. astromycterus , T. aff. caipora , T. ipatinga , T. nigricans , T. tantalus and T. vinnulus (all with three or more lateral-line pores); character 4 distinguishes T. alternatus from T. astromycterus and T. tantalus (both with a concave caudal fin); and character 5 distinguishes T. alternatus from T. astromycterus (with II + 8 or II + 9 dorsal-fin rays). Among congeners in the Rio Doce Basin , T. alternatus is most similar to T. barrocus and T. illuvies (both described in this paper). It can be distinguished from those two species, in addition to characters mentioned above, by the presence of a large fenestra between the orbitosphenoid and the frontal (vs. absent), by having fewer odontodes in the opercle (12–16) and interopercle (25–34) (vs. 15–25 opercular and 30–49 interopercular in T. barrocus and T. illuvies ) and by having more numerous dorsal procurrent rays in the caudal fin (18–25) (vs. 12–17 in T. barrocus and T. illuvies ). Trichomycterus alternatus can be further distinguished from T. barrocus by the deeper body (13.80–18.31% vs. 9.0–13.9%) and the larger prepelvic length (52.8–70.9% vs. 41.9–52.5%).

Description: Morphometric data for specimens examined is presented in Table 3. Body long and almost entirely straight, trunk roughly round in cross-section near head, then slightly deeper than wide and gently compressed towards caudal peduncle, tapering to caudal fin. Dorsal profile of body gently convex to dorsal-fin origin, then straight or slightly concave along caudal peduncle to caudal-fin origin. Ventral profile convex from gular region to vent, due partly to abdominal distension, then straight or slightly concave along anal-fin origin to caudal-fin base. Caudal peduncle almost as deep as body at beginning of anal-fin base.

Head approximately 1/5 of SL, pentagonal, slightly longer than wide and depressed. Mouth sub-terminal. Upper jaw slightly longer than lower one. Upper lip wider than lower lip, and laterally continuous with base of maxillary barbel. Lower lip small, approximately 2/3 width of upper one, partly divided into right and left portions by median concavity. Lower lip with uniform covering of tiny villi, not clustered into large papillae, resulting in velvet-like surface. Region between upper and lower lips with slender fleshy lobe.

Dentary and premaxillary teeth similar to each other in shape. Dentary teeth conical, arranged in two to four irregular rows, first row with 9–11 teeth, extending from base to slightly up of coronoid process, with size of individual teeth increasing markedly towards symphysis and from posterior to anterior rows. Premaxillary teeth conical, arranged irregularly in two to four rows over entire ventral surface of premaxilla, first row with 8–10 teeth. Total area of premaxillary teeth visually slightly smaller than that of dentary.

Eye medium sized, slightly protruding, positioned laterodorsally on head, without free orbital rim and covered with transparent skin. Eye located on anterior half of HL, closer to lateral border of head than to the midline in dorsal view. Anterior naris surrounded by tube of integument directed anterolaterally, continuous posterolaterally with nasal barbel. Posterior naris closer to anterior naris than to eyes, surrounded by tube of integument incomplete posteriorly. Maxillary barbel narrowing markedly towards fine tip, reaching anteromesial border of eyes or 1/4 of pectoral-fin base. Rictal barbel inserted immediately ventral to maxillary barbel, its tip reaching from anterior border of eyes to base of pectoral fin. Nasal barbel originating on posterolateral region of anterior naris, reaching anywhere from anterior border of posterior naris to posterior portion of opercle. Interopercular patch of odontodes medium to large compared to head length, oval in shape and with well-developed odontodes, prominent in ventral aspect of head. Interopercular patch of odontodes extending from vertical through ventroposterior border of eye to ventroanterior to opercle patch of odontodes. Odontodes arranged in three or four irregular series, with those on mesial series much longer than those on lateral one; odontodes gradually larger posteriorly in both series, with those posteriorly on mesial row largest. Interopercular odontodes 25–34. Opercular patch of odontodes on dorsolateral surface of posterior part of head, positioned anterodorsally to pectoral-fin base, roundish in shape and larger than eye in dorsal aspect of head. Opercular odontodes 12–16, sunk in individual slits of integument, progressively larger posteriorly, all with fine tips, with largest ones curved distally and claw-like. Entire patch surrounded by rim of integument.

Pectoral fin with its base immediately posterior and ventral to opercular patch of odontodes. Pectoral-fin rays I + 7. First pectoral-fin ray (unbranched) longest, prolonged as filament beyond fin margin, with variable length. Other rays progressively shorter, their tips following continuous line along fin margin. Pelvic fin with convex distal profile, just covering anal and urogenital openings in adults, its origin slightly posterior to middle of SL and anterior to vertical through dorsal-fin origin. Bases of pelvic fins separated by one eye diameter from each other. Pelvic-fin rays I + 4. Anterior process of basipterygium long and thin. Dorsal fin long, its distal margin sinusoidal. Dorsal-fin origin closer to base of caudal fin than to tip of snout. Dorsal-fin rays (ii or iii) + II + 7. Anal fin slightly smaller than dorsal fin, its distal margin gently convex. Anal-fin origin posterior to vertical through end of dorsal-fin base. Anal-fin rays (i, ii or iii) + II + 5. Caudal fin ranging from round to truncate in shape, with 6 + 7 principal rays. Adipose fin absent or represented by low integument fold extending between end of dorsal fin and caudal-fin origin. Post-Weberian vertebrae 34 (1), 35 (10), 36 (9), 37 (1). First dorsal-fin pterygiophore immediately anterior to neural spine of 15 th (5), 16 th (15), 17 th (2) vertebra, first anal-fin pterygiophore immediately anterior to neural spine of 19 th (2), 20 th (13), 21 st (7) vertebra. Caudal-fin procurrent rays plus one segmented non-principal ray dorsally and ventrally. Procurrent caudal-fin rays, 18–25 dorsally and 11–15 ventrally, beginning anteriorly at 28 th to 32 nd vertebrae. Ribs 10 (1), 11 (10), 12(9), 13 (4). Branchiostegal rays 6 (2) to 7 (18), some specimens with six on one side and seven on the other. Dorsal-fin pterygiophores 8. Anal-fin pterygiophores 6.

Cephalic lateral-line canals with simple non-dendritic tubes ending in single pores. Supraorbital canal mostly in frontal bone. Supraorbital pores invariably present: s1 mesial to nasal-barbel base and autopalatine, s3 mesial to posterior nostril and anterior to frontal, and single or paired s6 posteromedial to eye and at midlength of frontal. Infraorbital latero-sensory canal incomplete with four pores, i1 and i3 anteriorly and i10 and i11 posteriorly. This canal extending from sphenotic posteriorly to terminal pore located ventroposteriorly to eye. Infraorbital pore i1 located ventrolateral to nasal-barbel base and autopalatine, i3 ventrolateral to posterior nostril and anterior to frontal, i10 and i11 posterior to eye. Otic canal without pores. Postotic pores po1, anteromedial to opercular patch of odontodes, and po2, mesial to opercular patch of odontodes. Lateral line of trunk anteriorly continuous with postotic canal and reduced to short tube. Lateral line pores ll1 and ll2 dorsomedial to pectoral-fin base.

Coloration in ethanol: Pigmentation pattern extremely variable both within and among populations ( Figs 2–4). Basic colour of body consisting of large roundish maculae disposed in four irregular rows. One mid-dorsal row along entire dorsum, from occiput to dorsal edge of caudal peduncle. Second row ventrolateral to mid-dorsal one, extending from base of head, along upper part of flanks, entering dorsal half of caudal peduncle to base of caudal fin. Third row running along mid-lateral line, from end of opercle to base of caudal fin. Fourth row ventrolateral, less conspicuous and shorter than remaining three, extending along posterior part of abdomen, through posterior margin of pelvic fin to base of caudal fin. Four-row pattern partly or mostly disrupted by irregular fusions (mostly along anterior part of body) and misaligned maculae, resulting in various different configurations ( Figs 2–3). At one extreme, maculae are well separated by extensive white areas ( Fig. 3F). At other extreme, maculae are largely fused into nebulous pattern forming long stripes ( Fig. 3H) or barely discernible ( Fig. 3E). Intermediate patterns include partial or total fusion of mid-lateral row into mid-lateral stripe ( Fig. 3A, G-H) or overall fragmentation of maculae into nearly uniform mottled covering ( Fig. 3E, G). Middorsal row sometimes entirely fused into broad dark band ( Fig. 3H). Ventral row of spots sometimes as well-defined and conspicuous as other rows ( Fig. 3 A-C), sometimes reduced in size to irregular speckles or nearly absent ( Fig. 3 D-G). Ventral row usually restricted to posterior part of abdomen and caudal peduncle, extending anteriorly as cloud of small spots. Ventral side of abdomen lacking dark pigment. Head darkest on region corresponding to neurocranium, outlined by brain pigment seen by transparency. Dark spot at base of opercular patch of odontodes, with additional dark markings on cheeks. Distal margin of integument fold of opercular patch of odontodes darkly pigmented. Interopercular patch of odontodes unpigmented. Light teardrop-shaped area extending from posterior margin of eye to base of opercular patch of odontodes, corresponding to position of levator operculi muscle. Base of nasal barbel surrounded with concentration of dark pigment, extending posteriorly as elongate dark field to anterior margin of eyes. Dark pigmentation of fins restricted to irregular spots at bases of dorsal, caudal and pectoral fins, with thin dark streaks along fin rays.

Remarks: Trichomycterus alternatus was described from the Upper Rio Doce Basin in the town of Rio Doce , state of Minas Gerais (Reis & de Pinna, 2019). Representatives of the species have historically been reported from numerous south-eastern Brazilian localities, both in the Rio Doce and other basins ( Barbosa, 2004; Lima, 2008, 2021; Volpi, 2017; Lima et al., 2021). Widespread uncertainty about the application of the name T. alternatus lingered for a long time after its description, mostly due to confusion with C. zonata , and lack of detailed information on relevant type specimens, a situation which has recently been ameliorated (Reis & de Pinna, 2019). Material examined during the present work, including type specimens and samples from the type-locality, shows that T. alternatus is widespread throughout the Rio Doce Basin and several other south-eastern and south Brazilian basins. Such conclusion is corroborated by both morphological and molecular data, which show uniformity or continuity across the range of the species. Our comparative analysis included extensive representation of T. alternatus from the Lower, Middle and Upper Rio Doce , in addition to data from several other basins ( Rio Paraíba do Sul, Rio Itabapoana , Rio Paranaguá , Rio Cubatão and Rio Ribeira de Iguape ), covering a large portion of the south-eastern Brazilian region. Phylogenetic analysis (see Phylogenetic relationships above; Fig. 1) shows that samples of T. alternatus from across that range cluster in a clade. In combination with their phenotypic continuity, this strongly indicates the species is an evolutionarily cohesive unit (with some isolated diverging lineages, as discussed below). Interestingly, samples of T. alternatus from basins outside of the Rio Doce are mostly nested in populations of that basin. Such results have important consequences for inferences about the history of diversification and dispersion of T. alternatus (see Discussion).

Different populations of T. alternatus in the Rio Doce may show local morphological and colour pattern peculiarities which, if taken in isolation, seem to distinguish them from more typical specimens of T. alternatus . For example, some samples (e.g. MZUSP 110937, from Rio Piracicaba at Mariana, and MBML 6200 Santa Maria do Rio Doce , Santa Tereza) have long barbels relative to head length, resembling the phenotype described for T. longibarbatus (nasal barbel length: 78.4–102.6%; maxillary barbel length: 87.4– 113.2%).At the other extreme, barbels are short in some other populations (nasal barbel length: 34.2–62.3%; maxillary barbel length: 38.1–64.9%) (e.g. MZUSP 52542, from Santo Antônio River, Braúnas, MBML 2290, from Rio Guandu Basin at Afonso Cláudio), matching those considered typical of T. auroguttatus . Similar patterns of apparent differentiation occur also in the first pectoral-fin ray, which can be prolongued into a filament varying widely in length. Pronounced variation is also observed in pigmentation and the degree to which the pelvic fin reaches or covers the urogenital opening. The pigmentation pattern of T. alternatus is extremely variable, ranging from rows of round maculae along the body to fused maculae forming longitudinal dark stripes or irregular isolated maculae ( Fig. 3). The most morphologically divergent population examined of T. alternatus in the Rio Doce is from the Caratinga River in Minas Gerais State (MZUSP 123339) ( Figs 3H, 4). Specimens from that locality diverge from typical T. alternatus in features such as smaller head (HL 6.5–8.4% SL), shorter snout (41.2–52.1% HL), abrupt depression on caudal peduncle (9.5–11.6% SL), smaller and shallower caudal fin ( Figs 3H, 4) and a peculiar predominant colour pattern ( Figs 3H, 4). However, examination of numerous T. alternatus populations in the Rio Doce shows that such variation grades into one another, leaving no gaps or clear-cut distinctions that would indicate taxonomic differentiation at the species level, according to criteria adopted in this work. Colour pattern is in fact variable in that population, because one specimen in the lot has a typical T. alternatus pattern, and another has an intermediate condition ( Fig. 4). Unfortunately, samples of that population suitable for DNA analysis are not available, but phenotypic data do not support recognition of a separate species.

Similar conclusions are supported also by the lack of significant divergence in COI sequences in instances where data is available. An example is a population of T. alternatus from the Piranga River (Upper Rio Doce Basin ; MZUSP 94485) and another from Santa Maria do Rio Doce River (Lower Rio Doce Basin ; MBML 4642), which differ markedly in characters such as barbel length, first pectoral-fin ray length and to a small degree, colour pattern. In combination, the differences are suggestive of separate species under superficial examination. However, as in the previous example, there are intervening populations with intermediate conditions which bridge the apparent morphological gap. That inference is corroborated by a low COI divergence among various populations of T. alternatus (1.7%), well within estimates of intra- and interspecific genetic differentiation ( Sales et al., 2018) ( Table 2). A similar situation was reported by Nascimento et al. (2017) in Cambeva davisi , a species with wide variation in morphology and colour pattern. Although colour pattern has been shown to be conservative in some Trichomycterus species ( Bockmann & Sazima, 2004), this is by no means the rule in species of the genus, where colour pattern may be subject to pronounced polymorphism ( Arratia et al., 1978; Triques & Vono, 2004; Castellanos-Morales, 2007; Lima et al., 2008; Silva et al., 2010; Ferrer & Malabarba, 2013; Buckup et al., 2014). Marked degrees of intraspecific variation in colour pattern and other morphological traits exist in several Trichomycterus species in the Rio Doce , in addition to T. alternatus , such as T. argos , T. tantalus , T. ipatinga , T. immaculatus and T. vinnulus ( Figs 3–10, respectively). COI sequences of samples of T. tantalus , T. ipatinga , T. immaculatus and T. vinnulus lack significant intraspecific divergence (below 0.3%; Table 2), whereas T. alternatus has 1.7% divergence. Divergence below 2% has been shown to indicate 95% probability in belonging to the same species ( Ward et al., 2009). Similar results were reported for several other groups of fishes ( Hubert et al., 2008; Ward, 2009; Pereira et al., 2010, 2011; Carvalho et al., 2011; Mabragaña et al., 2011; Sales et al., 2018). Of course, a 2% barcoding divergence, in isolation, cannot be taken as an absolute threshold and may even be unrealistic for species of Trichomycterus and other taxa ( Pereira et al., 2010, 2013; Donin et al., 2020; de Queiroz et al., 2020). However, congruence of morphological and molecular data represents a strong signal that T. alternatus as recognized here is a single widespread species.

Considerationsaboveledustoproposeorconfirmsome nominal forms in our synonymic list of T. alternatus . Examination of type and non-type material referable to T. auroguttatus , T. longibarbatus and T. travassosi did not reveal evidence of differentiation beyond the clinal variation observed for T. alternatus in various phenotypic traits such as those described in species descriptions. Also, sequence data of samples putatively representing members of the three forms showed no significant differentiation from T. alternatus . With no evidence of species-level divergence from either morphology or DNA sequences, we consider these three forms are junior synonyms of T. alternatus , the oldest available name. Other previously described taxa, such as T. caudofasciatus ( Rio Itabapoana ) also fall in the T. alternatus clade according to COI data, but that taxon still needs a more detailed phenotypic assessment.

At the other end of the spectrum, there are taxa that differentiated to species-level in the T. alternatus lineage. Those species are subsets of T. alternatus which have diverged to separate species levels as evidenced by phenotypic data, such as T. astromycterus and T. vinnulus , as well as probably those which diverged in COI sequences but not in morphology, such as Trichomycterus sp. 1 and Trichomycterus sp. 2 discussed above. This implies that T. alternatus is a metaspecies ( Donoghue, 1985; de Queiroz & Donoghue, 1988; Archibald, 1994), with parts of it differentiated into full species, which we call exospecies. Unusually however, according to our analyses T. alternatus is polyphyletic, a relatively rare phenomenon also found in some species of Gymnotus ( Mutanen et al., 2016; Craig et al., 2019), rather than paraphyletic as in most documented cases of metaspecies [ Anetia jaegeri (Ménétriés, 1832) in Ackery & Vane-Wright 1984, Characidium zebra Eigenmann, 1909 in Buckup, 1992, Lariosaurus balsami Curioni, 1847 in Rieppel, 2000, Mastiglanis asopos Bockmann, 1994 in de Pinna & Keith, 2019 ] (see Discussion).Among a distantly related group of organisms, a case similar to that of T. alternatus happens with the distantly related macaque Macaca mulatta (Zimmermann, 1780) , widely distributed from Afghanistan to the east coast of China ( Fooden, 1980; Chu et al., 2007; Evans et al., 2020). That species forms a monophyletic group with Macaca fuscata Blyth, 1875 and Macaca cyclopis (Swinhoe, 1862) , both endemic to Pacific islands off the East Asian coast ( Japan and Taiwan, respectively). Considering their geographical range and mitochondrial DNA structure, their ancestor is inferred to have invaded those islands during periods of low sea level and then becoming isolated when the sea level rose. This event probably allowed populations of M. mulatta next to these islands to become molecularly closer to those two insular species, thus turning M. mulatta into a polyphyletic metaspecies (Hoelzer & Melnick, 1994; Chu et al., 2007).

Finally, there are cases of taxa that are phenotypically similar, if not identical, to T. alternatus which nonetheless lie outside of the species clade as defined here and seem to be a different species on the basis of DNA sequence differences alone. Such is the case with T. florensis (Miranda Ribeiro, 1943) , recently synonymized under T. santaeritae ( Eigenmann, 1918) ( Costa et al., 2020b) . The taxon reported as T. santaeritae in Costa et al. (2020b) indeed matches T. florensis , but not T. santaeritae . Data from the holotype and original description of T. santaeritae unambiguously show a fish with a round caudal fin, short nasal barbels and 11 dorsal pterygiophores, different from the emarginated caudal fin, long nasal barbels and eight dorsal pterygiophores of T. florensis and the specimens reported in Costa et al. (2020b). That being the case, T. santaeritae remains an enigmatic taxon in the genus, to our knowledge still known from the holotype only. In any case, T. florensis is morphologically similar to T. alternatus , with a colour pattern also well within the range of variation known for the latter species. Based on that alone, there would be little doubt that it represents simply an additional occurrence of T. alternatus . However, genetic distance and phylogenetic position indicate that it is an entirely different taxon, altogether outside of both the T. alternatus and the Rio Doce clades. Trichomycterus florensis , is sister group to T. caipora plus T. nigricans ( Fig. 1), both from the Paraíba do Sul Drainage. Based on such results plus information from Costa et al. (2020b), we found that T. florensis is a valid species, different from both T. alternatus and T. santaeritae .

Geographical distribution: Trichomycterus alternatus is distributed throughout the entire Rio Doce Basin ( Fig. 11), in tributaries of its upper, middle and lower courses. Records of the species are all from tributaries, sometimes close to their mouth on the Rio Doce , but not on the main river channel. Trichomycterus alternatus occurs also in most other basins in south-eastern Brazil, such as Cubatão, Itabapoana, Paraíba do Sul, Paranaguá and Ribeira do Iguape ( Barbosa, 2004; Volpi, 2017; Donin et al., 2020; Lima et al., 2021). The current confirmed range is from the Rio Doce in the north to the Rio Paranaguá in the south, but its precise limits are still undetermined.

Type material examined: holotype FMNH 58082, 65.6 mm SL; Rio Doce , near the village of Rio Doce , Minas Gerais, Brazil, Rio Doce Basin ; col. J. Haseman, 25 May 1908; paratypes FMNH 58083, 62, 30.4–57.9 mm SL; same data as holotype. Trichomycterus longibarbatus , all from Brazil, Espirito Santo, Santa Tereza; holotype MZUSP 043339, 1, 57.32 mm SL; near the village of Santa Tereza, Reis Magos River; col. M. Gomes, O. Peixoto, S. Carvalho & E. Izecksohn, 10 October 1991. Paratype MZUSP 023812, 17, 23.81–47.33 mm SL; Leste Drainage, Lombardina Creek; col. Zoology Department, MZUSP expedition, 2 April 1969. Trichomycterus auroguttatus , all from Brazil, Rio de Janeiro State; holotype MZUSP 43341, 1, 50.6 mm SL, 1 km to west of the village of Mauá, Marimbondo River, tributary of Rio Preto , Paraíba do Sul Basin; col. W.J.E.M. Costa & U. Neira, 1 December 1991. Paratype MZUSP 43342, 4, 33.8–47.68 mm SL; same locality of the holotype; col. W.J.E.M. Costa & U. Neira, 1 December 1991.

Additional specimens studied: Topotypic material of T. alternatus : MZUSP 123761, 1, 50.9 mm SL; Rio Doce Municipality, Córrego da Laje Creek near town of Rio Doce , tributary of main channel of Rio Doce Basin (20°14’13.05”S 42°56’53.65”W); col. V.J.C. Reis, M.C.C. de Pinna, G.F. de Pinna & G. Ballen, 23 June 2018. MZUSP 123763, 1, 46.3 mm SL; Rio Doce Municipality, Córrego dos Borges , stream flowing into left bank of Risoleta Neves Reservoir, Rio Doce Basin (20°12’21.63”S 42°52’56.24”W); col. V.J.C. Reis, M.C.C. de Pinna, G.F. de Pinna & G. Ballen, 24 June 2018. MZUSP 123764, 4, 42.7–47.3 mm SL; Rio Doce Municipality, Córrego dos Borges , stream flowing into left bank of Risoleta Neves Reservoir (20°12’22.03”S 42°52’57.44”W); col. V.J.C. Reis, M.C.C. de Pinna, G.F. de Pinna & G. Ballen, 24 June 2018. Brazil, state of Espírito Santo. MBML 607, 2, 39.2–56.1 mm SL; Itarana, Limoeiro Creek, tributary of Santa Joana Basin (19°52’26”S 40°52’31”W); col. R.L. Teixeira & P.S. Miller, 18 October 2000. MBML 646, 7, 21.1– 50.67 mm SL; Itarana, Jatibocas Creek, Santa Joana Basin (19°52’26”S 40°52’31”W); col. R.L. Teixeira & P.S. Miller, 19 April 2001. MBML 690, 6, 25–62.3 mm SL; Itarana, Jatibocas Creek, Santa Joana Basin (19°52’26”S 40°52’31”W); col. R.L. Teixeira & P.S. Miller, 10 August 2000. MBML 727, 1, 33.6 mm SL; Itarana, Santa Joana Basin (19°52’26”S 40°52’31”W); col. R.L. Teixeira & P.S. Miller, 18 October 2000. MBML 755, 9, 29–48 mm SL; Itarana, Jatibocas Creek, Santa Joana River (19°52’26”S 40°52’31”W); col. R.L. Teixeira & P.S. Miller, 18 October 2000. MBML 811, 1, 33 mm SL; Itarana, Jatibocas Creek, tributary of Santa Joana River (19°52’26”S 40°52’31”W); col. R.L. Teixeira & P.S. Miller, 8 February 2001. MBML 1051, 3, 55.4–76.3 mm SL; Santa Teresa, Vinte e Cinco de Julho Creek, at headwaters of Santo Antônio River, tributary of Santa Maria do Rio Doce Basin (19°56’08”S 40°36’01”W); col. R.L. Teixeira, 19 March 2005. MBML 1339, 2, 46.5– 57.4 mm SL; Santa Teresa, Rio Cinco de Novembro River , Santa Maria do Rio Doce Basin (19°56’08”S 40°36’01”W); col. R.L. Teixeira, 11 May 2005. MBML 1361, 3, 26.8–37.7 mm SL; Itarana, Córrego Sossego Creek, tributary of Santa Joana River (19°52’26”S 40°52’31”W); col. R.L. Teixeira, 20 August 2000. MBML 2230, 11, 28.8–59.6 mm SL; Afonso Cláudio, Córrego do Cedro Creek, Guandu Basin (20° 11 ’42”S 41°03’42”W); col. L.M. Sarmento-Soares, R.F. Martins-Pinheiro, A.T. Aranda, R.L. Teixeira, M.M.C. Roldi & M.M. Lopes, 12 June 2009. MBML 2234, 12, 26.8– 84.1 mm SL; Afonso Cláudio, Guandu Basin (20°09’16”S 41°05’59”W); col. L.M. Sarmento-Soares, R.F. Martins-Pinheiro, A.T. Aranda, R.L. Teixeira, M.M.C. Roldi & M.M. Lopes, 12 June 2009. MBML 2237, 3, 26.4– 39.6 mm SL; Laranja da Terra, Ribeirão Lagoa Stream, tributary of Guandu Basin (19°59’26”S 41°03’54”W); col. L.M. Sarmento-Soares, R.F. Martins-Pinheiro, A.T. Aranda, R.L. Teixeira, M.M.C. Roldi & M.M. Lopes, 12 June 2009. MBML 4306, 6, 20.9–56.8 mm SL; Iúna, Rio Claro River , tributary of Manhuaçu River (20°22’24.2”S 41°49’39.7”W); col. L.M. Sarmento-Soares, M.R. Britto, V.C. Espíndola, F.M.R.S. Pupo, R.F.M. Pinheiro & M.M.C. Roldi, 9 September 2011. MBML 4309, 2, 21.4–28.1 mm SL; Iúna, Ribeirão do Brás Creek, Manhuaçu Basin (20° 20’ 33.9 ”S 41°48’55.6”W); col. L.M. Sarmento-Soares, M.R. Britto, V.C. Espindola, F.M.R.S. Pupo, R.F.M. Pinheiro & M.M.C. Roldi, 10 September 2011. MBML 4338, 7, 27–38.5 mm SL; Júna, José Pedro River, tributary of Manhuaçu Basin (20°22’09.5”S 41°51’27.5”W); col. L.M. Sarmento-Soares, M.R. Britto, V.C. Espindola, F.M.R.S. Pupo, R.F.M. Pinheiro & M.M.C. Roldi, 10 September 2011. MBML 4438, 2, 26.3–40.0 mm SL; Santa Teresa, near Milanesi Municipality, Santa Maria do Rio Doce Basin (19°47’02.1”S 40°38’52.0”W); col. R.B. Soares, J. Gurtler & V.R. Bada, 24 September 2011. MBML 4642, 2, 38.2–47.5 mm SL; Santa Teresa, Santo Antônio Creek, Santa Maria do Rio Doce Basin (19°53’17.1”S 40°34’27.1”W); col. L.M. Sarmento-Soares, R.F.M. Pinheiro, M.M.C. Roldi & R.B. Soares, 12 February 2012. MBML 6160, 8, 27.1–56.2 mm SL; Santa Teresa, Espanhol Creek, Santa Maria do Rio Doce Basin (19°52’41.6”S 40°36’48.5”W); col. C.J. Cunha, J.P. Silva & R.B. Soares, 20 August 2012. MBML 6161, 13, 17.8–50.1 mm SL; Santa Teresa, Cinco de Novembro River, tributary of Santa Maria do Rio Doce Basin (19°53’49.2” S 40°36’10.9” W); col. C.J. Cunha, J.P. Silva & R.B. Soares, 20 August 2012. MBML 6200, 1, 47 mm SL; Cinco de Novembro River to the left of Es-080 road, straigth from Santo Antônio do Canaã to Santa Teresa municipalities, Santa Maria do Rio Doce River (19°49’42.9”S 40°38’18.4”W); col. C. J. Cunha, J. P. Silva e R. B. Soares, 20 August 2012. MBML 6207, 2, 32.1–36.5 mm SL; Santa Teresa, Cinco de Novembro River, at the left side of ES-080, straigth from Santo Antônio do Canaã to Santa Teresa, Rio Santa Maria do Rio Doce (19°50’26.0”S 40°37’47.3”W); col. C.J. Cunha, J.P. Silva & R.B. Soares, 20 August 2012. MBML 6210, 2, 36.3–37.1 mm SL; Santa Teresa, Espanhol Creek near to the mouth of Cinco de Novembro River, tributary of Santa Maria do Rio Doce Basin (19°52’41.6”S 40°36’48.5”W); col. C.J. Cunha, J.P. Silva & R.B. Soares, 20 August 2012. MBML 6211, 1, 38.6 mm SL; Santa Teresa, Cinco de Novembro River, tributary of Santa Maria do Rio Doce Basin (19°53’49.2”S 40°36’10.9”W); col. C.J. Cunha, J.P. Silva & R.B. Soares, 20 August 2012. MBML 6228, 12, 36.2– 76.7 mm SL, Brejatuba, Córrego da Passagem Creek, Guandu River (20°7’33.00”S 41°16’47.00”W); col. Biodiverses Project staff, 11 August 2012. MBML 6627, 2, 26.9–39.6 mm SL; Pancas, Cachoeira do Bassini Waterfall, Pancas Basin (19°50’26.0”S 40°37’47.3”W); col. C.J. Cunha, J.P. Silva & R.B. Soares, 20 August 2012. MBML 6822, 14, 33.3–55.3 mm SL; Santa Teresa, Vinte cinco de Julho River, tributary of Santa Maria do Rio Doce Basin (19°50’20.7”S 40°34’04.3”W); col. L.M. Sarmento-Soares, R.F. Martins Pinheiro, M.M.C. Roldi & R. Becalli, 5 May 13. MBML 6833, 4, 35.1–49.1 mm SL; Santa Teresa, Santo Antônio Creek, Santa Maria do Rio Doce Basin (19°53’04.4”S 40°34’30”W); col. L.M. Sarmento-Soares, R.F. Martins Pinheiro, M.M.C. Roldi & R. Becalli, 5 May 2013. MBML 6841, 5, 34.8–40.6 mm SL; Santa Teresa, Santo Antônio Creek, Santa Maria do Rio Doce Basin (19°53’20.3”S 40°34’32.8”W); col. L.M. Sarmento-Soares, R.F. Martins Pinheiro, M.M.C. Roldi & R. Becalli, 5 May 2013. MBML 6860, 6, 34.5– 63.5 mm SL; Santa Teresa, Santo Antônio River, tributary of Santa Maria do Rio Doce Basin (19°53’20.3”S 40°34’32.8”W); col. L.M. Sarmento-Soares, R.F. Martins Pinheiro, M.M.C. Roldi & R. Becalli, 5 May 2013. MBML 7598, 4, 43.1–74.1 mm SL; Afonso Cláudio, Córrego do Cedro Creek, tributary of Guandu River (20°11’42”S 41°03’43”W); col. T.A. Volpi & M.M. Lopes, 9 December 2013. MBML 7641, 42, 23.8–57.9 mm SL; Afonso Cláudio, Córrego do Cedro Creek, Guandu Basin (20°11’42”S 41°03’43”W); col. T.A. Volpi & M.M. Lopes, 9 December 13. MBML 7642, 6, 35.6–68.5 mm SL; Afonso Cláudio, Boa Sorte River, tributary of Guandu Basin (20°10’59”S 41°04’46”W); col. T.A. Volpi & M.M. Lopes, 9 December 2013. MBML 7665, 7, 19.8–39.1 mm SL; Pancas, Panquinhas Stream, tributary of Pancas Basin (19°13’00”S 40°52’01”W); col. T.A. Volpi & M.M. Lopes, 10 December 2013. MBML 7672, 2, 30.9–36.1 mm SL; Pancas, São Luís Creek, Pancas Basin (19°13’46”S 40°48’52”W); col. T.A. Volpi & M.M. Lopes, 11 December 2013. MBML 7681, 10, 24.6–32.2 mm SL; Santa Teres, Tabocas River, tributary of Pancas Basin (19°52’57”S 40°41’24”W); col. T.A. Volpi & M.M. Lopes, 11 December 2013. MBML 8191, 1, 39.3 mm SL; Iúna, José Pedro Stream, Manhuaçu Basin (20°22’10.4”S 41°51’28.4”W); col. T.A. Volpi, K.B.S. de Paula & E.L. Muhl, 10 May 2014. MBML 8426, 7, 28.8–47.4 mm SL; Santa Teresa, Santa Maria do Rio Doce Basin , near to its spring (19°57’52.5”S 40°44’20.4”W); T.A. Volpi, M.M. Lopes, K.B.S. de Paula & E.L. Muhl, 18 May 2014. MBML 8502, 2, 53.6–54 mm SL; Santa Teresa, Santa Maria do Rio Doce Basin (19°57’52.5”S 40°44’20.4”W); col. T.A. Volpi, M.M. Lopes, K.B.S. de Paula & E.L. Muhl, 18 May 2014. MBML 9977, 2, 34.3–44.5 mm Sl; Santa Teresa, Tabocas River, tributary of Santa Maria do Rio Doce Basin (19°52’57”S 40°41’24”W); col. T.A. Volpi & M.M. Lopes, 11 December 2013. Brazil, state of Minas Gerais. MZUSP 52542, 1, 45 mm SL; Braúnas, Pitangas Creek, tributary of Santo Antônio River; col. P.M.C. Araujo & F.A. Bockmann, 7 October 1997. MZUSP 58474, 1, 46.1 mm SL; Braúnas, Córrego do Gaspar Creek, Santo Antônio Basin (18° 58 ’60.00”S 42°44’21.00”W); col. P.M.C. Araujo & F.A. Bockmann, 4 October 1997. MZUSP 69366, 14, 31.8–51.7 mm SL; Coroaci, Suaçuí Basin (18°41’38.00”S 42°12’50.00”W); col. A.M. Zanata, 29 April 2001. MZUSP 72962, 81, 23.5–48.2 mm SL, 3 c&s 30.0– 48.9 mm SL; Santa Teresa, Reserva de Nova Lombardia (19°54’23.91”S 40°33’38.66”W); col. J.L. Helmer, 8 January 1993. MZUSP 73148, 8, 19.9–31.9 mm SL; Conceição do Mato Dentro, Rio do Peixe River, Santo Antônio Basin (19°11’14.20”S 43° 8’45.31”W); col. F. Di Dario & S. Kakinami, 13 September 2001. MZUSP 73163, 7, 16.6–29.9 mm SL; Conceição do Mato Dentro, Rio do Peixe, Santo Antônio Basin (19°11’40.04”S 43° 8’43.99”W); col. F. Di Dario & S. Kakinami, 14 September 2001. MZUSP 75254, 3, 81.5–85.7 mm SL; Ouro Preto, Tripuí Creek, tributary of Piranga Basin (20°23’45.63”S 43°34’11.92”W); col. M.R. Silvério, D.C. Oliveira & A. Oliveira, 1 March 2001. MZUSP 82369, 5, 50.0– 58.4 mm SL; Caranaíba, Papagaio River (20°51’12.00”S 43°43’12.00”W); col. J.C. Oliveira, A.L. Alves & L.R. Sato, 13 October 2001. MZUSP 82371, 1, 66.7 mm SL; Caranaíba, Piranga Basin (20°58’17.00”S 43°42’33.00”W); col. J.C. Oliveira, A.L. Alves & L.R. Sato, 12 October 2001. MZUSP 82370, 1, 42.9 mm SL; Desterro de Melo, Xopotó River, tributary of Piranga River (21°9’34.00”S 43°24’37.00”W); col. J.C. Oliveira, A.L. Alves, L.R. Sato, 12 October 2001. MZUSP 87825, 4, 48.0–61,6 mm SL; Santo Antônio do Itambé, Santo Antônio Basin (18°30’0.00”S 43°17’60.00”W); col. A. Carvalho Filho, 9 August 2004. MZUSP 87832, 5, 36.3–57.7 mm SL, 2 c&s, 52.3–52.6 mm SL; Santo Antonio de Itambé, Lageado Creek, Mão D’Água River, Santo Antônio Basin (18°28’27.12”S 43°17’29.27”W); col. A. Carvalho Filho, 30 August 2004. MZUSP 94485, 3, 34.5–42.3 mm SL; Alto Rio Doce, Xopotó River , tributary of Piranga River (21°4’4.00”S 43°27’50.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 11 July 2007. MZUSP 94486, 1, 27.8 mm SL; Alto Rio Doce Rio, Xopotó River , tributary of Piranga River (21°4’4.00”S 43°27’50.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 11 July 2007. MZUSP 94503, 3, 42.8–50.8 mm SL; Caranaiba, Piranga River (20 ° 51 ’ 37.00 ” S 43°43’11.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 9 July 2007. MZUSP 94512, 4, 34.3–39.0 mm SL; Alto Rio Doce, Xopotó River, Piranga River (21°3’11.00”S 43°26’46.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 11 July 2007. MZUSP 94518, 2, 54.3–62.6 mm SL; Desterro de Melo; Xopotó River, tributary of Piranga River (21°9’29.00”S 43°32’34.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 10 July 2007. MZUSP 94520, 2, 43.2– 60.2 mm SL; Caranaiba, Piranga River (20°52’52.00”S 43°44’15.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 9 July 2007. MZUSP 94522, 7, 43.0– 62.1 mm SL; Caranaiba, Piranga Basin (20°52’52.00”S 43°44’15.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 9 July 2007. MZUSP 94531, 3, 29.2–48.1 mm SL; Desterro de Melo, Xopotó River, tributary of Piranga Basin (21 ° 9 ’ 10.00 ” S 43°31’49.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 10 July 2007. MZUSP 94536, 2, 26.2–35.5 mm SL; Desterro de Melo, Xopotó River, Piranga Basin (21°9’10.00”S 43°31’28.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 9 July 2007. MZUSP 94538, 3, 44–47.1 mm SL; Desterro de Melo, Xopotó River, tributary of Piranga Basin (21 ° 9 ’ 10.00 ” S 43°31’28.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 10 July 2007. MZUSP 94547, 14, 22.8–39.7 mm SL; Carandaí, Piranga Basin (20 ° 57 ’ 45.00 ” S 43°41’48.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 9 July 2007. MZUSP 94548, 6, 32.3–58.5 mm SL; Carandaí, Piranga River (20 ° 57 ’ 45.00 ” S 43°41’48.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 9 July 2007. MZUSP 94564, 75, 37.0– 55.7 mm SL, 3 c&s 40.14–46.0 mm SL; Desterro de Melo, Xopotó River, tributary of Piranga River (21°8’53.00”S 43°30’46.00”W); col. O. Oyakawa, E. Baena & M. Loeb, 10 July 2007. MZUSP 109302, 5, 33.3–53.1 mm SL, 2 c&s, 39.7–40.9 mm SL; Conceição do Mato Dentro, Santo Antônio Basin (18°43’50.00”S 43°26’8.00”W); col. T.C. Pessali, December 2010. MZUSP 109304, 4, 21.3–40.6 mm SL; Conceição do Mato Dentro, Santo Antônio Basin (18°53’18.00”S 43°27’7.00”W); col. T.C. Pessali, December 2010. MZUSP 109311, 4, 33.8– 49.0 mm SL, 1 c&s 41 mm SL; Conceição do Mato Dentro, Santo Antônio Basin (18°49 ’44.00”S 43°24’25.00”W); col. T.C. Pessali, December 2010. MZUSP 109313, 2, 49.2–49.7 mm SL; Conceição do Mato Dentro, Santo Antônio Basin (18°48’16.00”S 43°26’16.00”W); col. T.C. Pessali, December 2010. MZUSP 109319, 3, 31.0– 33.3 mm SL; Conceição do Mato Dentro, Santo Antônio Basin (18°59’25.00”S 43°26’47.00”W); col. T.C. Pessali, December 2010. MZUSP 109352, 1, 39 mm SL; Catas Altas, Paracatu Creek, tributary of Piracicaba Basin (20° 6’53.00”S 43°24’31.00”W); col. B. Maia, 31 March 2010. MZUSP 109391, 3, 42.7–64.1 mm SL, 1 c&s 52 mm SL; Santa Bárbara, Ribeirão Preto Creek, tributary of Piracicaba Basin (20° 3’57.00”S 43°40’16.00”W); col. B. Maia, 31 July 2010. MZUSP 109392, 1, 59 mm SL; Santa Barbara, Ribeirão Preto, tributary of Piracicaba Basin (20°3’57.00”S 43°40’16.00”W); col. B. Maia, August 2010. MZUSP 110933, 1, 37.1 mm SL; Mariana, Gualaxo do Sul River (20°30’16.97”S 43°24’39.28”W); col. L.F. Salvador Jr. & L.A.C. Missiaggia, 5 July 2012. MZUSP 110937, 1, 66.6 mm SL; Mariana, Piracicaba Basin (20°13’48.93”S 43°27’14.34”W); col. L.F. Salvador Jr. & L.A.C. Missiaggia, 5 October 2012. MZUSP 112753, 4, 35.9–41.8 mm SL; Ferros, Santo Antônio Basin (19°13’34.50”S 43° 1’9.50”W); col. O.T. Oyakawa & T.F. Teixeira, 16 August 2012. MZUSP 121709, 1, 48.5 mm SL; Coronel Fabriciano, Cachoeira do Escorrega Waterfall, tributary of Piracicaba Basin (19°25’0.42”S 42°43’20.68”W); col. V.J.C. Reis, 22 March 2017. MZUSP 69333, 1, 63 mm SL; Coroací, Suaçuí Basin (18°36’45.93”S 42°16’52.91”W); col. A.M. Zanata, 28 April 2001. MZUSP 121710, 1, 48.9 mm SL; Coronel Fabriciano, Cachoeira do Escorrega Waterfall, Piracicaba Basin (19°25’0.42”S 42°43’20.68”W); col. V.J.C. Reis, 22 March 2017. MZUSP 121719, 4, 40.9– 52.1 mm SL; Santana do Paraíso, Piracicaba Basin (19°19’20.24”S 42°31’38.49”W); col. V.J.C. Reis, 23 March 2017. MZUSP 123339, 15, 14, 30.8–68.6 mm SL, 3 c&s, 33.2–34.9 mm SL; Santa Rita de Minas, Caratinga River, tributary of Rio Doce Basin (19°51’20.22”S 42°8’24.63”W); col. T. Pessali, 8 September 2015. MZUSP 123393, 1, 43.5 mm SL; Baguarí, main stream of Rio Doce (19°1’14.00”S 42°7’14.40”W); col. V.J.C. Reis & T. Pessali, 12 November 2017. LBP 1013, 1, 62.1 mm SL; Caranaíba, Piranga River (21°8’56.82”S 43°23’58.38”W); col. J.C. Oliveira, A.L. Alves & L.R. Sato, 12 October 2001. LBP 1016, 3, 44.3–56.5 mm SL; Caranaíba, Piranga River (20°58’10.26”S 43°42’19.86”W); col. J.C. Oliveira, A.L. Alves & L.R. Sato, 13 October 2001. LBP 1020, 12, 36.2–51.1 mm SL; Caranaíba, Papagaio River (20°51’7.74”S 43°43’7.62”W); col. J.C. Oliveira, A.L. Alves & L.R. Sato, 13 October 2011. LBP 8350, 1, 39 mm SL; Ferros, Piçarrão River (19°16’43.87”S 42°53’53.40”W); col. C. Oliveira, G.J.C. Silva, F.F. Roxo & T.N.A. Pereira, 18 May 2009. LBP 12259, 15, 35.1– 56.8 mm SL; Desterro de Melo, Xopotó River (21°9’9.70”S 43°31’37.90”W); col. A. Ferreira, F.F. Roxo & G.J. Costa e Silva, 19 June 2011. MNRJ 1152, 16, 31.6–66.2 mm SL; Viçosa, Piranga River (20°44’51.10”S 42°51’35.95”W); col. J. Moojen Oliveira, no date. MNRJ 22400, 6, 32.8–56.3 mm SL; Caparaó, Grumarim Creek, tributary of Capim Roxo River (20°31’38.69”S 41°53’33.83”W); col. A.T. Aranda, F.A.G. Melo & F.P. Silva, 7 August 2001. MNRJ 30980, 2, 62.8–76.0 mm SL; Senhora dos Remédios, Piranga River (21° 2’13.69”S 43°35’46.63”W); col. M. Britto, N. Tamaio & I. Tamaio, 30 December 2006. MNRJ 39468, 9, 25.2–40.1 mm SL; Alto Caparaó, Caparaó River, tributary of Manhuaçu Basin (20°27’ 38.26”S 41°52’5.40”W); col. L.M. Sarmento-Soares, M.R. Britto, 9 September 2011. MNRJ 42745, 1, 68.3 mm SL; Caparaó, Caparaó River, tributary of Manhuaçu River (20°32’0.17”S 41°54’34.70”W); col. P. Buckup, M. Britto & D.F. Moraes Jr., 14 April 2014. MNRJ 43174, 1, 60.6 mm SL; Alto Caparaó, Caparaó River, tributary of Manhuaçu Basin (20°28’39.58”S 41°52’25.50”W); col. E. Pauls, 8 May 1997. MNRJ 50893, 3, 43.5–43.8 mm SL; Serra Azul, main stream of Suaçuí Grande Basin; col. S.A. Santos & T.C. Pessali, 16 February 2018.

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Kingdom

Animalia

Phylum

Chordata

Order

Siluriformes

Family

Trichomycteridae

Genus

Trichomycterus