Zoosyst. Evol. 100 (1) 2024, 223-231 | DOI 10.3897/zse.100.115564 Gag tuseuM ror BERLIN Relationships and description of a new catfish species from Chapada Diamantina, the northernmost record of 7richomycterus 5.8. (Siluriformes, ‘Trichomycteridae) Wilson J. E. M. Costa!, Caio R. M. Feltrin', José L. O. Mattos!, Axel M. Katz! 1 Laboratory of Systematics and Evolution of Teleost Fishes, Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil https://zoobank. org/0E463E5B-8BE7-49F9-98E7-B170F 1SCDC6B Corresponding author: Wilson J. E. M. Costa (wcosta@acd.ufr).br) Academic editor: Nicolas Hubert # Received 9 November 2023 # Accepted 7 February 2024 # Published 6 March 2024 Abstract Psammocambeva exhibits the largest geographical distribution amongst the subgenera of Trichomycterus s.s., with its present northernmost represented by 7richomycterus tete, endemic to the upper Rio de Contas Basin in the Chapada Diamantina Region, north-eastern Brazil. Herein, we describe a new species recently collected in the Chapada Diamantina Region, but in the Rio Paraguac¢u Basin, about 100 km north of the area inhabited by 7° rete. A molecular phylogeny using one nuclear and two mitochondrial genes (2430 bp) supported the new species as sister to 7’ tete; both species are distinguished by colour patterns, morphometric data, relative position of dorsal and anal fins and osteological character states. The clade comprising the new species and 7: tefe, endemic to the semi-arid Caatinga biogeographical province, is supported as sister to a clade comprising species from the Rio Doce and Rio Paraiba do Sul Basins, in the Atlantic Forest biogeographical province. This study corroborated the Chapada Diamantina Region, a well-known mountainous biodiversity centre, as an important centre of endemism for trichomycterid catfishes. Key Words Caatinga, molecular phylogeny, mountain biodiversity, osteology, Rio Paraguacu Introduction The Trichomycterinae (hereafter trichomycterines) are the most common fish group in South American mountainous regions (Costa 2021). In eastern and north-eastern Brazil- ian highlands, trichomycterines are represented by the ge- nus 7richomycterus Valenciennes, 1832, which in its strict sense (1.e. Zrichomycterus s.s.) 1s a well-supported clade, which is sister to a clade containing the genera Cambeva Katz, Barbosa, Mattos & Costa, 2018 and Scleronema Eigenmann, 1917 (Katz et al. 2018). Trichomycterus s.s. includes the type species of the genus, 7richomycterus ni- gricans Valenciennes, 1832 and others about 80 species, in six subgenera (Costa 2021). Amongst these subgenera, Psammocambeva Costa, 2021, presently including 35 nominal species, exhibits the largest geographical dis- tribution and is the only one occurring in north-eastern Brazil (Costa 2021; Vilardo et al. 2023). Psammocam- beva is well-supported in molecular phylogenies, but it is not diagnosable by unique morphological character states, with species positioning being determined mainly by molecular phylogenies, besides the absence of synapo- morphic osteological characteristics of other genera and, exceptionally, by the presence of derived osteological characteristics that are shared by groups of species within Psammocambeva (Costa 2021; Costa et al. 2022, 2023). The present northernmost record for Psammocambeva, as well as for Trichomycterus s.s., is Trichomycterus tete Barbosa & Costa, 2011, endemic to the Rio de Contas Ba- sin, southern Chapada Diamantina, north-eastern Brazil (Barbosa and Costa 2011). Recently, one of us (CRMF) collected another species of Psammocambeva in the Cha- pada Diamantina, but in the Rio Paraguacu Basin, about 100 km north of the area inhabited by 7° fete in the Rio de Copyright Costa, W.J.E.M. et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 224 Contas Basin. The objectives of the present study are to conduct a phylogenetic analysis to investigate the position- ing of the new species and to present a formal description. Materials and methods Field studies were approved by ICMBio (Instituto Chico Mendes de Conservacao da Biodiversidade; permit num- ber: 38553-13) and field methods by the Ethics Commit- tee for Animal Use of Federal University of Rio de Janeiro (permit number: 065/18). Euthanasia, fixation, preparation for morphological studies and conservation followed meth- ods of our previous studies on trichomycterine systematics (e.g. Costa et al. (2023)). In lists of specimens, C&S indi- cates cleared and stained specimens for osteological anal- yses and DNA indicates specimens directly fixed and pre- served in absolute ethanol. Geographical names followed Portuguese terms used in the region. Specimens were de- posited in the Instituto de Biologia, Universidade Federal do Rio de Janeiro (UFRJ). Comparative material is listed in Costa et al. (2022, 2023). Methods to take and express morphometric and meristic data, morphological terminolo- gy, selection of described and illustrated osteological struc- tures and sequence of morphological characters used in the Species description are according to our previous studies on Psammocambeva (Costa et al. 2022, 2023). Proceedings for DNA extraction, amplification and se- quencing, reading and interpretation of sequencing chro- matograms and sequences annotation were according to our previous studies on systematics of Psammocambeva (e.g. Costa et al. (2023)). Primers for PCR reactions for the three genes used in the analysis, the mitochondrial genes cytochrome b (CYTB) and cytochrome c oxidase I (COX1) and the nuclear en- coded gene recombination activating 2 (RAG2), were the same used in other studies on Psammocambeva (e.g. Cos- ta et al. (2023)). The concatenated molecular data matrix comprised 2430 bp (COX1 521 bp, CYTB 1088 bp, RAG2 821 bp). Parameters for PCR reactions and thermal profile of PCR protocol were the same used in Costa et al. (2023). The sequencing reaction thermal profile was 35 cycles of 30 s at 95 °C, 30s at 55 °C and 1.5 min at 73 °C. GenBank accession numbers are provided in Table 1. Terminal taxa for the phylogenetic analyses comprised the new species and 22 species of Psammocambeva rep- resenting all included lineages. Outgroups were four con- geners representing other subgenera of 7richomycterus s.S., two species of the clade Cambeva plus Scleronema, the sister group of 7richomycterus s.s., one species of a distantly related trichomycterine genus, two species representing other Trichomycteridae subfamilies and one species of the Nematogenyidae, the sister group of Trichomycteridae. Alignment of individual gene datasets was made with the Clustal W algorithm (Chenna et al. 2003) implemented in MEGA 11 (Tamura et al. 2021). The optimal partition scheme and the best-fit evolutive models (Table 2) were calculated using the Partition- Finder 2.1.1 (Lanfear et al. 2016) software, based on the zse.pensoft.net Costa, W.J.E.M. et al.: New catfish from Chapada Diamantina Table 1. Species used in the phylogenetic analyses and respec- tive GenBank accession numbers. COX1 CYTB RAG2 Nematogenys inermis KY857952 ~ KY858182 Trichogenes longipinnis MK123682 MK123704 MF431117 Microcambeva ribeirae MN385807 OK334290 MN385832 [tuglanis boitata MK123684 MK123706 MK123758 Scleronema minutum MK123685 MK123707 MK123759 Cambeva barbosae MK123689 MK123713 MN385820 Trichomycterus itatiayae MW671552 MW679291 OL779233 Trichomycterus nigricans MN813005 MK123723 MK123765 Trichomycterus albinotatus MN813007 MK123716 MN812990 Trichomycterus brasiliensis MK123691 MK123717 MK123763 Trichomycterus travassosi MK123701 MK123730 OL752425 Trichomycterus alterrnatus 0Q357886 00355710 0Q400957 Trichomycterus pantherinus MK123697 MK123725 MN812989 Trichomycterus goeldii MT435136 M1436453 M1446427 Trichomycterus jacupiranga OL764372 OL779234 OL779232 Trichomycterus pradensis MN813003 MK123726 MN812988 Trichomycterus melanopygius 0Q357896 0Q355720 0OQ400967 Trichomycterus auroguttatus MT435135 M1436452 OP699434 Trichomycterus saquarema OP698258 OP688464 OP688470 Trichomycterus macrophthalmus OL741727 = OL752426 OL752421 Trichomycterus astromycterus ONO36881 OK652453 OK652448 Trichomycterus altipombensis |OP698260 OP688466 OP688472 Trichomycterus puriventris OP698259 OP688465 OP688471 Trichomycterus mimosensis 0Q357893 00355719 0Q400966 Trichomycterus longibarbatus 0Q357895 0Q355718 OQ400965 Trichomycterus gasparinii OR354437 OR356032 0Q400962 Trichomycterus vinnulus ONO36819.1 OK652452 OK652449 Trichomycterus barrocus 0Q357889 00355713 0Q400959 Trichomycterus ipatinga 0Q357892 0Q355716 0OQ400963 Trichomycterus illuvies 0Q357894 00355717 0Q400964 Trichomycterus tete OL741729 MH620966 - Trichomycterus diamantinensis OR435278 OR438925 OR438926 Trichomycterus caudofasciatus - MK123719 MK123764 Table 2. Best-fitting partition schemes and evolutive models. Partition Base pairs Evolutive Model COMM 174 GTR+I GOK Len 174 F81 COX1 3" 173 GTR+G ey Bel 363 K80+1+G CYB 363 HKY +1 CyIBis 362 GTR+G RAG2 1st 455 K80+1+G RAG2 2" 274 GTR+G RAG2 3" 243 K80+G Corrected Akaike Information Criterion. Bayesian Infe- rence was performed with MrBayes 3.2.7a (Ronquist et al. 2012), using two independent Markov Chain Monte Carlo (MCMC) runs with 5 x 107 generations; sampling frequency of every 1000 generations; Tracer 1.7.2 (Ram- baut et al. 2018) for evaluation of convergence of the MCMC chains, attainment of the stationary phase, effec- tive sample size adequacy and determination of the burn- in percentage; and 25% burn-in to calculate Bayesian posterior probabilities. Maximum Likelihood (ML) was performed using IQ-TREE 2.2.0 (Minh et al. 2020), with node support estimated through both ultrafast bootstrap (Hoang et al. 2018) and traditional bootstrap (Felsenstein 1985), with 1000 replicates for each one. Zoosyst. Evol. 100 (1) 2024, 223-231 Results Phylogenetic analyses The phylogenetic analyses generated identical trees (Fig. 1), in which the new species 1s highly supported as sister to T. tete, the only other species of 7richomycterus endemic to the Chapada Diamantina. Taxonomic accounts Trichomycterus (Psammocambeva) diamantinensis sp. nov. https://zoobank. org/2E7EOCOD-2FC6-452B-95EF-8931787C2D73 Figs 2, 3, 4A—C, Table 3 Type material. Holotype. Brazit * 1 ex., 82.2 mm SL; Bahia State: Palmeiras Municipality: Vale do Capao Dis- trict: Rio da Bomba, tributary of Rio Preto, Rio Santo Antonio drainage, Rio Paraguacu Basin; 12°39'35"S, 41°29'14"W; about 980 m as.1.; 15 May 2023; C. R. M. Feltrin, R. dos Santos-Junior, and G. L. Canella, leg; UFRJ 13688. Paratypes. Brazit * 3 ex. (DNA), 39.7-60.5 mm SL; collected with holotype; UFRJ 13686; * 3 ex. (C&S), 49 .4—70.0 mm SL; collected with holotype; UFRJ 13689; ¢ 2 ex., 27.1 and 79.6 mm SL; collected with holotype; UFRJ 13690. Diagnosis. Trichomycterus diamantinensis is distin- guished from all other species of Psammocambeva by having a unique colour pattern of adult specimens con- sisting of a faint brown stripe along the lateral mid-line of trunk, overlapped by a great concentration of rounded light brown spots 1n a more superficial layer of skin (vs. never a similar colour pattern). Trichomycterus diaman- tinensis also differs from its hypothesised sister species and the only other species of the CD-clade, T tete, by having the anal-fin origin at a vertical posterior to the dorsal-fin base (vs. through the posterior portion of the dorsal-fin base), a longer nasal barbel, its tip posteriorly reaching the opercular patch of odontodes (vs. reaching area between the orbit and the opercular patch of odon- todes), 39 or 40 vertebrae (vs. 36 or 37), a deeper body (body depth 14.0-17.3% SL vs. 12.5—13.2%), a deeper caudal peduncle (caudal peduncle depth 11.5-12.9% SL vs. 9.7-10.8%), a wider body (body width 11.2—-12.3% SL vs. 7.3—9.0%), a wider head (head width 83.1—89.3% of head length vs. 68.7—77.5%), the anal-fin origin at a vertical through the centrum of the 25" vertebra (vs. 22™ or 23" vertebra), the sesamoid supraorbital slender, with- out a lateral process (Fig. 4A; vs. with a lateral expansion, often forming a distinctive process, Fig. 4D), a relatively wider metapterygoid and quadrate (Fig. 4B vs. Fig. 4E) and a minute ventral middle foramen of the parurohyal (Fig. 4C; vs. broad, Fig. 4F). Description. General morphology. Morphometric data are in Table 3. Body moderately slender, head and trunk excluding caudal peduncle with dorsal profiles 225 Table 3. Morphometric data of Trichomycterus diamantinensis Sp. nov. Holotype Paratypes (n=4) Standard length (SL) 70.0 49.4-79.6 Percentage of standard length Body depth 14.0 14.9-17.3 Caudal peduncle depth 11.5 11.6-12.9 Body width ipa 11.5-12.3 Caudal peduncle width 5.1 4.1-5.5 Pre-dorsal length 63.7 62.6-64.3 Pre-pelvic length 59.3 58.3-61.0 Dorsalfin base length 10.0 10.6-11.6 Anal-fin base length 8.1 8.0-10.3 Caudal-fin length 170 14.6-16.5 Pectoral-fin length 14.1 12.8-13.3 Pelvic-fin length 8.9 9.4-9.6 Head length 19.7 18.5-20.8 Percentage of head length Head depth 48.8 51.4-55.3 Head width 84.0 83.1-89.3 Snout length 42.7 39.7-44.0 Interorbital width 26.0 26.4-29.9 Pre-orbital length 12.2 14.2-15.6 Eye diameter 13:1 12.2-16.9 slightly convex, and ventral profile nearly straight, dor- sal and ventral profiles of caudal peduncle approximately straight. Greatest body depth at vertical just anterior to pelvic-fin base. Trunk subcylindrical anteriorly, com- pressed posteriorly. Anus and urogenital papilla at vertical through dorsal-fin origin or just posterior to it. Head sub- trapezoidal in dorsal view, snout profile slightly convex. Eye relatively small, dorsally positioned in head, nearer snout margin than opercle. Posterior nostril located near- er anterior nostril than orbital rim. Tip of maxillary barbel posteriorly reaching between posterior limit of interoper- cular patch of odontodes and pectoral-fin base, rictal barbel reaching posterior portion of interopercular patch of odontodes and tip of nasal barbel reaching opercular patch of odontodes. Mouth subterminal. Jaw teeth point- ed, slightly curved, arranged in irregular rows. Premax- illary teeth 45—50, dentary teeth 44-50. Odontodes con- ical, elongate; opercular odontodes arranged in irregular transverse rows, interopercular odontodes arranged in irregular longitudinal rows. Opercular odontodes 17-19, interopercular odontodes 38-42. Branchiostegal rays 7. Dorsal and anal fins subtriangular, anterior and poste- rior margins slightly convex. Total dorsal-fin rays 12 (i + II + 7), total anal-fin rays 10 (ii + IT + 5); anal-fin ori- gin at vertical just posterior to dorsal-fin base end. Dor- sal-fin origin at vertical through centrum of 20" vertebra; anal-fin origin at vertical through centrum of 25" verte- bra. Pectoral fin subtriangular in dorsal view, posterior margin slightly convex, first pectoral-fin ray terminating in filament, its length about 25% of pectoral-fin length without filament. Total pectoral-fin rays 8 (I + 7). Pel- vic fin subtruncate, its posterior extremity not reaching urogenital papilla, at vertical through dorsal-fin origin or immediately posterior to it. Pelvic-fin bases medially in close proximity. Total pelvic-fin rays 5 (I + 4). Caudal fin truncate. Total principal caudal-fin rays 13 (I + 11 + I), zse.pensoft.net 226 "E19 */95/73 Rk "HIO9 87/84/54°094/9° TK sf i £2. 97/78/58 */94/87 "FI99 3 bat kl Trichomycterus jacupiranga Trichomycterus gasparinii Trichomycterus vinnulus jichomyctorus pantherinus Trichomycterus travassosi Trichomycterus macrophtalmus 7 Trichomycterus altipombensis Trichomycterus saquarema 7 Trichomycterus puriventris Trichomycterus caudofasciatus Trichomycterus mimosensis a Trichomycterus alternatus "gyicnom ycterus astromycterus ~ Trichomycterus goeldii _ Trichomycterus auroguttatus \_ Trichomycterus longibarbatus Trichomycterus melanopygius */99/*__ | |*/*;9gl- Trichomycterus ipatinga Trichomycterus illuvies Trichomycterus barrocus Trichomycterus tete Trichomycterus diamantinensis Trichomycterus pradensis (/ 97/96 Trichomycterus albinotatus i Trichomycterus brasiliensis Trichomycterus nigricans Trichomycterus itatiayae Costa, W.J.E.M. et al.: New catfish from Chapada Diamantina ooceeeeeeeeeeee. Sammocambeva Scleronema minutum Cambeva barbosae Ituglanis boitata »—_____. Microcambeva ribeirae Trichogenes longipinnis 14. Nematogenys inermis 0.07 Figure 1. Bayesian Inference topology calculated using MrBayes 3.2.7a for 33 taxa. The dataset comprised two mitochondrially encoded genes (COI, CYTB) and one nuclear gene (RAG2), with a total of 2430 bp. The numbers above branches indicate Bayesian posterior probabilities from the Bayesian Inference analysis and the ultrafast bootstrap and regular bootstrap values from the Max- imum Likelihood analyses, respectively, separated by a bar. Asterisks (*) indicate maximum support values and dashes (-) indicate values below 50. total dorsal procurrent rays 17 or 18 (xvi-xvii + J), total ventral procurrent rays 13 or 14 (xii—xii + I). Latero-sensory system. Supraorbital canal, posterior section of infraorbital canal and postorbital canal contin- uous. Supraorbital sensory canal with 3 paired pores: s1, adjacent to medial margin of anterior nostril; s3, adjacent and just posterior to medial margin of posterior nostril and s6, at transverse line through posterior half of orbit; s6 pore about equidistant from its symmetrical homolo- gous s6 pore than orbit. Infraorbital sensory canal with 2 segments. Anterior infraorbital canal with 2 pores: il, at zse.pensoft.net transverse line through anterior nostril and 13, at trans- verse line just anterior to posterior nostril. Posterior in- fraorbital canal with two pores: 110, adjacent to ventral margin of orbit and ill, posterior to orbit. Postorbital canal with 2 pores: pol, at vertical line above posterior portion of interopercular patch of odontodes, and po2, at vertical line above posterior portion of opercular patch of odontodes. Lateral line of trunk with 2 pores just poste- rior to head. Osteology (Fig. 4A—C). Anterior margin of meseth- moid nearly straight, mesethmoid cornu rod-shaped, Zoosyst. Evol. 100 (1) 2024, 223-231 227 Figure 2. Trichomycterus (Psammocambeva) diamantinensis sp. nov., UFRJ 13688, holotype, 82.2 mm SL: A. Left lateral view; B. Dorsal view; C. Ventral view. tip rounded. Lacrimal oval, its largest length about one third of sesamoid supraorbital length. Sesamoid supra- orbital narrow, rod-like, longer than premaxilla largest length. Premaxilla sub-rectangular in dorsal view, slight- ly tapering laterally. Maxilla boomerang-shaped, slender, slightly shorter than premaxilla, with minute posterior process. Autopalatine sub-rectangular in dorsal view when excluding posterolateral process, its shortest width about half autopalatine length, lateral and medial margins weakly concave. Latero-posterior process of autopala- tine triangular, its length about two thirds of autopalatine length excluding anterior cartilage. Metapterygoid sub- triangular, deeper than long, with distinctive posterior projection; anterior margin weakly bent, posterior margin slightly sinuous. Quadrate robust, dorsoposterior out- growth in close proximity to hyomandibular outgrowth. Hyomandibula long, anterior outgrowth with small con- cavity on dorsal margin. Opercle moderately elongate, opercular odontode patch slender, its depth about half length of dorsal articular facet of hyomandibula; dorsal process of opercle short and blunt. Interopercle long, its longitudinal length about three fourths of hyomandibula longitudinal length. Preopercle compact, without ventral expansion. Parurohyal robust, lateral process relatively elongate, sharply pointed. Parurohyal head well-devel- oped, with minute anterolateral paired process. Middle parurohyal foramen small, its largest length about one fourth of distance between anterior margin of parurohy- al and anterior insertion of posterior process. Posterior parurohyal process long, slightly longer than distance between anterior margin of parurohyal and anterior in- sertion of posterior process. Vertebrae 39 or 40. Ribs 13. Two dorsal hypural plates, corresponding to hypurals 4 + 5 and 3, respectively; single ventral hypural plate corre- sponding to hypurals 1 and 2 and parhypural. Colouration in alcohol (Figs 2, 3). Dorsum and flank brownish-grey, lighter ventrally, with faint brown stripe along lateral mid-line of trunk, overlapped by great con- centration of rounded light brown spots extending over flank and dorsum in more superficial layer of skin. Dorsum zse.pensoft.net 228 Costa, W.J.E.M. et al.: New catfish from Chapada Diamantina Figure 3. Trichomycterus (Psammocambeva) diamantinensis sp. nov., UFRJ 13690, paratype, 27.1 mm SL: A. Left lateral view; B. Dorsal view; C. Ventral view. light brown with yellowish-grey with mid-dorsal row of small brown spots between nape and dorsal-fin origin. Dor- sal and lateral portions of head brownish-grey with brown spots. Ventral surface of head and trunk white. Jaws and barbels brown. Fins hyaline, with faint brown spots on bas- al portion of unpaired and pectoral fins. Smallest specimen (27.1 mm SL) with flank pale yellow and narrow black stripe along lateral mid-line, which becomes paler and dif- fuse and overlapped by brown spots in larger specimens. Distribution and habitat. 7richomycterus diamantin- ensis is presently known only from the type locality, the Rio da Bomba, a tributary of the Rio Preto, Rio Santo Antonio drainage, Rio Paraguacu Basin (Fig. 5). Rio da Bomba at the type locality is a dark-coloured small river, about 15 m wide and about | m at deepest places, with dense riparian forest in the river banks (Fig. 6). Speci- mens of 7. diamantinensis were found amongst small and medium-sized loose stones, with diameters ranging from 1 cm to 50 cm, approximately, in shallow (about between 5 and 50 cm) and fast-flowing places, with the zse.pensoft.net presence of mosses, algae and fallen leaves composing the microhabitats. They were collected both in shaded and fully sun-exposed places. Etymology. The name diamantinensis is an allusion to the occurrence of the new species in the Chapada Diamantina, north-eastern Brazil. Discussion The present description of 7? diamantinensis expands the distribution of Trichomycterus s.s. about 100 km to north, consisting of the first record of the genus for the Rio Para- guacu Basin, an important fluvial system of north-eastern Brazil, with a surface area about 54,900 km2. A previous record of the occurrence of 7richomycterus further north in north-eastern Brazil by Sarmento-Soares et al. (2011), in the Rio Itapicuru Basin, was actually due to a misplace- ment of the species /tuglanis payaya (Sarmento-Soares, Zanata & Martins-Pinheiro, 2011), as discussed by Costa Zoosyst. Evol. 100 (1) 2024, 223-231 229 garner B ; metapterygoid maxilla hyomandibula mesethmoid lacrimal autopalatine quadrate preopercle lateral ethmoid sesamoid supraorbital interopercle frontal D E | i metapterygoid ~—hyomandibula premaxilla maxilla “7S lacrimal mesethmoid quadrate preopercle autopalatine lateral ethmoid interopercle c frontal sesamoid supraorbital ° a Figure 4. Osteological structures of A—C. Trichomycterus diamantinensis sp. nov., D—-F. T. tete. A, D. Mesethmoidal region and adjacent structures, left and middle portions, dorsal view; B, E. Left jaw suspensorium and opercular series, lateral view; C, F. Paru- rohyal, ventral view. Larger stippling represents cartilaginous areas. 42° 0° W 39° 54’ W 13° 12'S ro " 39° 54’ W Figure 5. Map of geographical distribution of: 1. Trichomycterus diamantinensis sp. nov. and 2. T. tete. et al. (2021). No species of 7richomycterus s.s. wasfound T. tete from the Rio de Contas Basin (Fig. 1). No other during our field studies in the Rio Itapicuru Basin. species of Trichomycterus s.s. is known to occur in the This study supported a clade endemic to the Chapada _ Caatinga. The analysis indicated that the clade comprising Diamantina Region, in the semi-arid Caatinga biogeo- ‘7’ diamantinensis and T. tete is sister to a well-supported graphical province (sensu Morrone (2006)), comprising — clade including species endemic to the Rio Doce Basin, in T: diamantinensis from the Rio Paraguacu Basin and _ the Atlantic Forest biogeographical province: Trichomyc- zse.pensoft.net 230 fee ern te Sree t Figure 6. Rio da Bomba at the type locality of Trichomycterus diamantinensis sp. Nov. terus barrocus Reis & de Pinna, 2022, Trichomycterus illuvies Reis & de Pinna, 2022, Trichomycterus ipatinga Reis & de Pinna, 2022 and Trichomycterus melanopygius Reis, dos Santos, Britto, Volpi & de Pinna, 2020. Recent molecular data indicated that Trichomycterus brucutu Reis & de Pinna, 2022 from the Rio Doce Basin is also a member of this group (Vilardo et al. 2023), here named as the Psammocambeva beta-clade. Our molecular studies in progress and molecular data presented in Reis and de Pinna (2022) support Trichomycterus tantalus Reis & de Pinna, 2022 also from the Rio Doce Basin as closely re- lated to T. ipatinga and T: melanopygius. Trichomycterus tantalus is distinguishable from Trichomycterus largoper- culatus Costa & Katz, 2022, a species endemic to the Rio Paraiba do Sul Basin, south-eastern Brazil, not available for molecular analyses, only by minor morphological features (1.e. odontode counts) and both species share river migrating habits (Costa and Katz 2022; Reis and de Pinna 2022). Thus, available evidence indicates that 7: largoperculatus and T. tantalus are also members of the Psammocambeva beta-clade. On the other hand, the pres- ent study supports 7richomycterus pradensis Sarmen- to-Soares, Martins-Pinheiro, Aranda & Chamon, 2005, a species occurring in coastal river basins of north-eastern Brazil (Sarmento-Soares et al. 2005), as distantly related to the Psammocambeva beta-clade. Relationships of oth- er nominal species morphologically similar and occurring in areas close to the distribution area of 7. pradensis (e.g. Trichomycterus bahianus Costa, 1992, Trichomycterus itacambirussu Triques & Vono, 2004, Trichomycterus Jequitinhonhae Triques & Vono, 2004 and Trichomycter- us landinga Triques & Vono, 2004) are still unknown. The colour pattern of adult specimens of 7? diamantinen- sis, comprising dark pigmentation occurring tn two layers of the skin, with a faint brown stripe along the lateral mid- line of the trunk at an internal layer, overlapped by a great concentration of rounded light brown spots at a more ex- ternal layer (Fig. 2), immediately distinguishes this species from all other congeners of Psammocambeva. In T. tete, its hypothesised sister species, the colour pattern consists of dark pigmentation arranged in a single layer, forming round spots separated by broad interspaces (Barbosa and Costa zse.pensoft.net Costa, W.J.E.M. et al.: New catfish from Chapada Diamantina 2011: fig. 1). However, juvenile specimens below about 30 mm SL of both species (Fig. 3), share an identical colour pattern, in which the flank is pale yellow with a narrow black stripe along the longitudinal mid-line, possibly cor- roborating sister group relationships, since no other species of Psammocambeva has a similar colour pattern in juvenile specimens. In the distantly-related Trichomycterus saquare- ma Costa, Katz, Vilardo & Amorim, 2022, in addition to a broad black stripe along the lateral mid-line, there 1s another stripe on the dorsal part of the flank (Costa et al. 2022: fig. 14C), thus considered a non-homologous condition. The sources of the Rio Paraguacu are located in the Chapada Diamantina, a well-known mountainous biodi- versity centre with numerous endemic plants (Giulietti et al. 1997). The present study corroborates the Chapa- da Diamantina as an important centre of endemism for trichomycterid catfishes. In addition to 7’ diamantin- ensis and T. tete, endemic trichomycterids include the whole subfamily Copionodontinae (de Pinna 1992), two species of the trichomycterine genus /tuglanis Costa & Bockmann, 1993 (Campos-Paiva and Costa 2007; Costa et al. 2021) and one species of the sarcoglanidine genus Ammoglanis Costa, 1994 (Costa et al. 2020). Acknowledgements We are grateful to Ronaldo dos Santos-Junior and Gustavo L. Canella for assistance during field studies. Instituto Chi- co Mendes de Conservacaéo da Biodiversidade provided collecting permits. Thanks are also due to Felipe Ottoni and Valter Azevedo-Santos for comments and suggestions. This work was partially supported by Conselho Nacion- al de Desenvolvimento Cientifico e Tecnologico (CNPq; grant 304755/2020-6 to WJEMC) and Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ; grant E-26/201.213/2021 to WJEMC, E-26/202.005/2020 to AMK and E-26/202.327/2018 to JLM). This study was also supported by CAPES (Finance Code 001) through Programa de Pés-Graduacao em Bio- diversidade e Biologia Evolutiva /UFRJ and Programa de Pos-Graduacéo em Genética/UFRJ. References Barbosa MA, Costa WJEM (2011) Description of a new species of the catfish genus Trichomycterus (Teleostei: Siluriformes: Trichomycte- ridae) from the rio de Contas basin, northeastern Brazil. Vertebrate Zoology 61(3): 307-312. https://doi.org/10.3897/vz.61.e31157 Campos-Paiva RM, Costa WJEM (2007) Ituglanis paraguassuensis sp. n. (Teleostei: Siluriformes: Trichomycteridae): a new catfish from the rio Paraguac¢u, northeastern Brazil. 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