Trichomycterus brunoi, BARBOSA & COSTA, 2010

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 : 387-394

TRICHOMYCTERUS BRUNOI BARBOSA & COSTA, 2010

( FIG. 12)

Trichomycterus brunoi Barbosa & Costa, 2010: 97 , figs 1, 3 [type locality: Brazil: state of Minas Gerais: Alto Caparaó Municipality: lateral channel of Rio Caparaó , Rio Itabapoana Basin, Alto Caparaó , 20°25’54”S 41°51’57”W, elevation 1047 m; holotype: UFRJ 6030, paratypes: UFRJ 5649 (11), 5650 (2), 5658 (5, c&s); Sarmento-Soares et al., 2011: 262 (citation, diagnosis); Barbosa & Costa, 2012: 159 (citation, relationships); Barbosa & Azevedo-Santos, 2012: 358 (citation, diagnosis); Barbosa, 2013: 274 (citation, relationships); García-Melo et al., 2016: 237 (citation, relationships); Barbosa & Katz, 2016: 262 (citation, relationships).

Diagnosis: The combination of the following traits distinguishes T. brunoi from congeners: (1) pectoral-fin rays I + 6 (vs. I + 5, I + 7 or I + 8); (2) colour pattern composed of stripes, vermiculations or reticulations; (3) eight branchiostegal rays (vs. either fewer or more); and (4) minute foramen for ramus lateralis accessorius facialis nerve on parietosupraoccipital, visible in dorsal view (vs. foramen large, well visible in dorsal view). Among congeners in south-eastern South America, character 1 distinguishes T. brunoi from all congeners except T. pirabitira , T. itatiayae , T. trefauti , those in the T. reinhardti species complex ( Costa & Katz, 2021), except from T. humboldti , T. pauciradiatus , T. piratymbara and T. sainthilairei and those in the T. brasiliensis species complex ( Barbosa & Costa, 2010; Costa, 2021); character 2 from all congeners except for those in the T. brasiliensis species complex, plus T. lauryi and T. pirabitira ; character 3 from all congeners except for T. argos , T. brucutu , T. giganteus , T. ipatinga , T. itatiayae , T. mimosensis , T. nigroauratus , T. pirabitira and Trichomycterus potschi Barbosa & Costa, 2003 ; character 4 from T. argos . Among congeners in the Rio Doce Basin , T. brunoi is most similar to T. argos . In addition to characters above, T. brunoi can be further distinguished from T. argos by the shorter snout (28–41.2% SL vs. 41.9–45.9% SL), by the shorter prepelvic length (41.4–58.5% SL vs. 59.5– 60.6% SL) and by the fewer interopercular odontodes (26–31 vs. 39–40).

Description: Morphometric data for specimens examined is presented in Table 8. Body long and almost straight, trunk roughly round in cross-section near head, then slightly deeper than wide and gently compressed to 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 as deep as body at end of anal-fin base.

Head approximately 1/5 to 1/4 of SL, pentagonal, longer than wide and depressed, with a long snout. Mouth subterminal. Upper jaw slightly longer than lower jaw. 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, resulting in velvet-like surface and not clustered into large papillae. 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 four irregular rows, first row with 12 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. Total area of premaxillary teeth slightly smaller than that of dentary, with teeth arranged irregularly in four rows, first row with approximately 13 teeth, over entire ventral surface of premaxilla. Premaxillary teeth conical.

Eye small, protruding, positioned dorsally 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 tubular narrowing markedly towards fine tip, reaching until half of pectoral-fin length. Rictal barbel inserted immediately ventral to maxillary barbel, its tip reaching gill opening. Nasal barbel originating on posterolateral region of anterior naris, reaching until posterior region of the opercle, not surpassing it. Interopercular patch of odontodes small 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. Odontodes arranged in two or three 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 26–31. Opercular patch of odontodes on dorsolateral surface of posterior part of head, positioned an interodorsally to pectoral-fin base, roundish in shape slightly smaller than eye in dorsal aspect of head. Opercular odontodes 13–16, 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 fleshy fold rim of integument.

Pectoral fin with its base immediately posterior and ventral to opercular patch of odontodes. Pectoral-fin rays I + 6. First pectoral-fin ray (unbranched) longest, prolonged as filament beyond fin margin. Other rays progressively shorter, their tips following continuous line along fin margin. Pelvic fin with convex distal profile, its origin slightly posterior to middle of SL and anterior to vertical through dorsal-fin origin, slightly surpassing anal and urogenital openings in adults. Pelvic-fin rays I + 4. 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 + II + 7 (3). 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 ii + II + 5 (1) or iii + II + 5 (1). Caudal fin rounded in shape with 6 + 7 principal rays. Adipose fin absent or modified into low integumentary fold extending between end of dorsal fin and caudal-fin origin. Post-Weberian vertebrae 36 (1) or 38 (2). First dorsal-fin pterygiophore immediately anterior to neural spine of 18 th (3) vertebra, first anal-fin pterygiophore immediately anterior to neural spine of 21 st (3) vertebra. Caudal-fin procurrent rays plus one segmented non-principal ray dorsally and ventrally. Procurrent caudal-fin rays, 16 dorsally and 13 ventrally, beginning anteriorly at 32 nd (1) vertebrae. Ribs 12 (2) or 13 (1). Branchiostegal rays 8. 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, s6 paired and close to each other, posteromedial to eye and at midlength of frontal. Infraorbital laterosensory canal incomplete with four pores, i1 and i3 anteriorly and i10 and i11 posteriorly, extending from sphenotic posteriorly to terminal pore located ventroposteriorly to eye. Infraorbital pore i1 located ventro-lateral 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: Dark chromatophores agglutinating into round to vermiculate maculae. Individual maculae eye-sized or smaller, randomly distributed on body, except ventrally, from head to base of middle caudal-fin rays. Anteriorlly at midline of body, maculae sometimes roughly organized in line, coalescing into broken stripes. Maculae roundish and widely spaced-out ventral to lateral midline. Dorsal to lateral midline, maculae more numerous and predominantly vermiculate, often coalescent. Ventral part of body lacking dark pigmentation. Dark spots on bases of fins excluding pelvics.

Remarks: Trichomycterus brunoi belongs to the T.brasiliensis species complex( Barbosa&Costa, 2010), comprising T. brasiliensis , Trichomycterus claudiae Barbosa & Costa, 2010 , T. fuliginosus , Trichomycterus macrotrichopterus Barbosa & Costa, 2010 , Trichomycterus maracaya Bockmann & Sazima, 2004 , Trichomycterus mariamole Barbosa & Costa, 2010 , Trichomycterus mimonha Costa, 1992 , Trichomycterus mirissumba Costa, 1992 , Trichomycterus novalimensis Barbosa & Costa, 2010 , T. potschi , Trichomycterus rubiginosus Barbosa & Costa, 2010 , Trichomycterus vermiculatus (Eigenmann, 1917) and T. argos (herein included in the group; see Remarks for T. argos ). Its placement in that assemblage is supported by the presence of I + 6 pectoral-fin rays, a colour pattern consisting of small dark maculae, usually horizontally distended, randomly distributed on flanks forming a vermiculated pattern, a slender posterior tip of the posterior ceratohyal and pelvic-fin bases closely-set ( Barbosa & Costa, 2003; Bockmann & Sazima, 2004; Barbosa & Costa, 2010). Results from multilocus analyses and ultraconserved elements ( Ochoa et al., 2017, 2020; Katz et al., 2018) have shown that species belonging to the T. brasiliensis species complex form a monophyletic group, but an analysis including all of its putative species has not yet been done.

The type locality of T. brunoi is in the Upper Rio Itabapoana , near the divide with the headwaters of the Rio Manhuaçu (tributary to Rio Doce ; Fig. 13) and other specimens were collected in the latter. The species most similar to T. brunoi in the Rio Doce Basin is Trichomycterus argos , described from the Rio Casca , a tributary of the Upper Rio Doce in the Serra do Brigadeiro State Park.

Barbosa & Costa (2010) distinguished T. brunoi from all species of the T. brasiliensis species complex, except T. fuliginosus , by the unique morphology of the metapterygoid, which has a distinct posterior process directed towards the anterior tip of the hyomandibula. However, the same posterior process of the metapterygoid is herein recorded also in T. claudiae , T. mariamole , T. novalimensis , T. rubiginosus and T. brasiliensis . In T. claudiae , there is an intermediate condition with a small posterior process on the metapterygoid, directed towards the anterior tip of the hyomandibula ( Fig. 21; modified from Barbosa & Costa, 2010). The condition of this character varies considerably, with wide overlap among species in the T. brasiliensis species complex and does not seem to clearly diagnose T. brunoi .

Geographical distribution: Trichomycterus brunoi was described from the Itabapoana Basin in the Caparaó State Park and is also present in the Rio Doce at Rio Manhuaçu ( Fig. 13).

Additional material: MBML 4304, 4, 29.6–55.1 mm SL; Brazil, Espírito Santo, Iúna ; Rio Claro River, Manhuaçu River (20°22’22.00”S 41°49’40.90”W); col. L.M. Sarmento-Soares, M. R. Britto, V. C. Espindola, F.M. R. S. Pupo, R. F.M. Pinheiro and M.M.C. Roldi, 9 September 2011 . MBML 4307, 1, 32.5 mm SL; Brazil, Espírito Santo, Iúna ; Rio Claro River, Manhuaçu River (20°22’24.20”S 41°49’39.70”W); col. L.M. Sarmento-Soares, M. R. Britto, V. C. Espindola, F.M. R. S. Pupo, R. F.M. Pinheiro and M.M.C. Roldi, 9 September 2011 . MBML 4308, 2, 30.2–41.7 mm SL, 1 c&s, 31.93 mm SL; Brazil, Espírito Santo, Iúna; Ribeirão do Brás Creek, Manhuaçu River (20°20’33.90”S 41°48’55.60”W); col. L.M. Sarmento-Soares, M. R. Britto, V. C. Espindola, F.M. R. S. Pupo, R. F.M. Pinheiro and M.M.C. Roldi, 10 September 2011 . MNRJ 22401 , 2 , 33.6 –75.0 mm SL; Brazil, Minas Gerais, Caparaó; Grumarim Creek, tributary of the Capim Roxo River (20 o 30’48’’S 42 o 1’19” W); col. A. T. Aranda, F.A.G. Melo & F.P. Silva, 7 August 2001 .

TRICHOMYCTERUS AFF. CAIPORA LIMA, LAZZAROTTO & COSTA, 2008

( FIG. 22)

Diagnosis: The combination of the following traits distinguishes this species from congeners: (1) short nasal, maxillary and rictal barbels, not reaching eyes (vs. barbels reaching or surpassing eyes); (2) marbled colour pattern formed by large round maculae blurred by dark chromatophores over entire body; (3) three lateral-line pores (vs. two); (4) interopercular odontodes 47–63 (vs. fewer); and (5) pectoral-fin rays I + 7 (vs. I + 5, I + 6 or I + 8). Among congeners in south-eastern South America, character 1 distinguishes T. aff. caipora from all congeners except for some morphs of T. alternatus , T. astromycterus , T. barrocus and T. lauryi ; character 2 from all congeners except for T. barrocus ; character 3 from all congeners except for T. astromycterus , T. ipatinga , T. nigricans , T. tantalus and T. vinnulus ; character 4 from all congeners except for T. barrocus , T. caipora , T. melanopygius , T. lauryi and T. tantalus ; and character 5 from species in the T. brasiliensis and T. reinhardti species complexes ( Barbosa & Costa, 2010; Costa, 2021; Costa & Katz, 2021), plus T. trefauti (all preceding with I + 6 or fewer), and from T. astromycterus , T. caipora , T. giganteus , T. immaculatus , T. lauryi , T. nigricans and T. tantalus (the last seven species with I + 8 or more). Among congeners in the Rio Doce Basin , T. aff. caipora is most similar to T. barrocus . In addition to the characters above, T. aff. caipora is further distinguished from T. barrocus by the smaller eye, 12.2–14.4% HL (vs. 14.8–17.5%) and by having six branchiostegal rays (vs. seven).

Description: Morphometric data for specimens examined is presented in Table 9. Body long and almost straight, trunk roughly round in cross-section near head, then slightly deeper than wide and gently compressed to 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 slightly as deep as body at end of anal-fin base.

Head approximately one-fifth of SL, pentagonal, longer than wide and depressed. Mouth subterminal. Upper jaw slightly longer than lower. 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, resulting in velvet-like surface and not clustered into large papillae. Region between upper and lower lips with slender fleshy lobe. Dentary teeth conical. Total area of premaxillary teeth slightly smaller than that of dentary. Premaxillary teeth conical.

Eye medium sized, one-seventh of head length, protruding, positioned dorsally 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 short, wide at base, narrowing markedly towards fine tip, reaching anteromesial margin of interopercle. Rictal barbel short, inserted immediately ventral to maxillary barbel, its tip goes until the most anteromesial portion of interopercle. Nasal barbel short and wide at base, originating on posterolateral region of anterior naris, its tip reaching slightly beyond eye. Interopercular patch of odontodes 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 to 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 47–63. 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 24–28, 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 fleshy fold 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) longer, prolonged as filament beyond fin margin. Other rays progressively less longer, their tips following continuous line along fin margin. Pelvic fin with convex distal margin, its origin slightly posterior to middle of SL and anterior to vertical through dorsal-fin origin. Pelvic-fin bases close to each other, their tips touching but not covering anal and urogenital openings. Pelvic-fin rays I + 4. Dorsal fin long, its distal margin sinusoidal. Dorsal-fin origin closer to base of caudal fin than to tip of snout. Dorsal-fin rays iii + II + 7 (1). 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 iii + II + 5 (1). Caudal fin round shape, with 6 + 7 principal rays. Adipose fin absent or modified into low integumentary fold extending between end of dorsal fin and caudal-fin origin. Post-Weberian vertebrae 37 (1). First dorsal-fin pterygiophore immediately anterior to neural spine of 18 th (1) vertebra, first anal-fin pterygiophore immediately anterior to neural spine of 22 nd (1) vertebra. Caudal-fin procurrent rays plus one segmented non-principal ray dorsally and ventrally. Procurrent caudal-fin rays, 12 (1) dorsally and 11 (1) ventrally, beginning anteriorly at 33 rd (1) vertebrae. Ribs 13 (1). Branchiostegal rays 6 (1). 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 laterosensory canal incomplete with four pores, i1 and i3 anteriorly and i10 and i11 posteriorly. Canal extending from sphenotic posteriorly to terminal pore located ventroposteriorly to eye. Infraorbital pore i1 located ventrolaterally 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, ll2 and ll3 dorsomedial to pectoral-fin base.

Coloration in ethanol: Dark chromatophores distributed on inner and outer skin layers. Chromatophores on inner skin layer forming large roundish to ameboid blotches, larger than eye diameter, longitudinally aligned and partly coalescent, forming longitudinal stripes along body. Outer skin layer of pigmentation masking underlying pigmentation. Dorsum with two rows of dark blotches from head to caudal fin, extending bilaterally alongside dorsal midline on dorsum. Between lateral line of dorsum and the lateral midline, unpigmented area formed by lack of dark pigment on inner layer, creating lightly-coloured band from dorsal margin of opercle to base of upper caudal-fin rays. Lateral midline with broad dark stripe from dorsal margin of opercle to base of middle caudal-fin rays, mixing with adjacent maculae from middle caudal peduncle to base of caudal fin.Ventral to lateral midline, chromatophores organized in dusky blotches, sometimes forming round maculae. All fins heavily darkly-pigmented, except for margins, creating effect of distal white band. Ventral part of body lacking dark pigment. Head darkest on region corresponding to neurocranium, outlined by brain pigment seen by transparency. Light teardrop-shaped area extending from posterior margin of eye to base of opercular patch of odontodes, corresponding to levator operculi muscle. Base of nasal barbels surrounded with concentration of dark pigment, extending posteriorly as elongate dark field to anterior margin of eyes. Distal margin of integumentary fold of opercular patch of odontodes darkly pigmented. Interopercular patch of odontodes white.

Remarks: Trichomycterus aff. caipora is a large-sized Trichomycterus species when compared to its congeners from south-eastern Brazil.Although superficially similar to T. caipora from the Macabu River Basin, the form herein reported from the Rio Doce differs substantially in COI sequence distance. Our phylogenetic analysis indicates that the two forms are not even closely related, with the form from the Rio Doce internested in the Doce clade, as sister group to T. tantalus and in a subclade including also T. ipatinga and T. melanopygius . Trichomycterus caipora from Macabu River, in turn, is closely related to T. nigricans and at multiple levels to many other species in that basin. Some phenotypic differences also exist between the two forms which agree with the observed sequence differentiation, such as the number of pectoral-fin rays, number of sensory pores in the lateral line and number of post-Weberian vertebrae. The Rio Doce form is clearly a different, yet undescribed species. Because we have but a single sequence sample of T. aff. caipora , its phyletic status could not be determined at this time. We refer to it as T. aff. caipora simply because of superficial similarity to that species, but it remains unnamed. The taxon is currently under more detailed study by S. Santos and collaborators.

Geographical distribution: Trichomycterus aff. caipora occurs in the headwaters of the Rio Santo Antônio , Rio Suaçuí Grande and Rio Caratinga ( Fig. 23). It has not yet been recorded from the main channel of the Rio Doce. The geographical distribution of T. caipora is the Rio Macabu Basin, Lagoa Feia System (historically connected with the Rio Paraíba do Sul).

Material examined: All from Brazil, state of Minas Gerais. MZUSP 73162 , 78.3 mm SL; Conceição do Mato Dentro Municipality , Rio do Peixe River, tributary of Santo Antônio River (19°12’1.83”S 43°8’32.41”W); col. F. Di Dario & S. Kakinami, 14 January 2001 ; MZUSP 80309 , 2 , 82.6–92.4 mm SL; Suaçuí Grande River , Rio Doce Basin (18°29’48.86”S 42°19’53.66”W); col. C.B.M. Alves, 16 March 2001 . MZUSP 123340 , 1 , 92.8 mm SL; Iapú Municipality , Caratinga River, Rio Doce Basin (19°28’36.41”S 42°7’44.44”W); col . T. Pessali , 8 October 2015 .