Trachelyichthys, MEES, 1974

GENUS TRACHELYICHTHYS MEES, 1974 View in CoL (CLADE 80)

Trachelyichthys Mees, 1974: 111 View in CoL (type species: Trachelyichthys decaradiatus Mees, 1974 View in CoL ; type by original designation and monotypy. Gender masculine).

Included species: Trachelyichthys decaradiatus Mees, 1974 View in CoL , Trachelyichthys exilis Greenfield & Glodek, 1977 View in CoL and Trachelyichthys sp. 1 Calegari, Akama & Ferraris, undescribed.

Diagnosis: Trachelyichthys is diagnosed by 14 morphological synapomorphies. Non-exclusive: (1) outer pair of mental barbels long, surpassing posterior margin of coracoid process (char. 3509: 0 → 1), convergent in Auchenipterus , Epapterus , Pseudepapterus , Pseudauchenipterus nodosus , Trachelyopterus coriaceus , Trachelyopterus striatulus , Trachelyopterus porosus and Trachelyopterus aff. T. porosus ; (2) anterior fontanel rounded (char. 3542: 2 → 1), convergent in Gelanoglanis pan , Spinipterus and some species of Tatia ; (3) dorsal margin of lateral ethmoid not exposed on dorsal surface of cranium (char. 3546: 0 → 2), convergent in Centromochlus , Duringlanis, Gelanoglanini , Glanidium cesarpintoi , Glanidium sp. 2 RS, Pseudauchenipterus , Liosomadoras , Tatia (except Tatia intermedia ), Tetranematichthys , Trachelyopterus lucenai and Trachelyopterus cf. Trachelyopterus galeatus ; (4) lateral margin of frontal not participating in orbital margin (char. 3553: 1 → 0), convergent in Entomocorus , Tocantinsia , Trachycorystes trachycorystes and Centromochlinae ; (5) posterior process of epioccipital bifurcated (char. 3563: 0 → 1), convergent in Auchenipterus , Epapterus , Pseudepapterus , Tetranematichthys and Trachelyopterus ; (6) posterior process of epioccipital and parapophyses of compound centrum connected by suture (char. 3566: 0 → 1), convergent in Ageneiosini , Auchenipterus , Epapterus , Pseudepapterus and Trachelyopterus coriaceus ; (7) coronomeckelian bone separated from anguloarticular (char. 3597: 1 → 0), convergent in Centromochlinae (except Centromochlus , Glanidium catharinensis , Glanidium ribeiroi , Glanidium sp. 2 RS), Pseudauchenipterus jequitinhonhae , Pseudauchenipterus nodosus and Pseudepapterus ; (8) adductor crest of hyomandibula absent or indistinguishable (char. 3616: 1 → 0), convergent in several auchenipterids; (9) suprapreopercle elongate, tubular in shape, much longer than wide (char. 3624: 0 → 1), convergent in several auchenipterids; (10) second hypobranchial cartilaginous (char. 3646: 0 → 1), exclusive in Auchenipterinae , convergent in Gelanoglanis stroudi and Gelanoglanis travieso ; (11) postzygapophysis of compound centrum extended up to seventh vertebra (char. 3666: 4 → 3), convergent in Tympanopleura , Auchenipterus , Balroglanis macracanthus , Duringlanis romani , Entomocorus , Pseudauchenipterus and Trachelyopterus teaguei ; (12) compound centrum including up to seventh vertebra (char. 3667: 4 → 3), convergent in Centromochlinae (except Centromochlus , Ferrarissoaresia , Glanidium catharinensis and Glanidium cesarpintoi ), Auchenipterini (except Pseudepapterus ), Trachelyopterus albicrux and Trachelyopterus teaguei ; (13) posterior nuchal plate narrower than base of dorsal-fin spine (char. 3673: 1 → 0), convergent in Ageneiosini¸ Auchenipterus, Gelanoglanini , Entomocorus , Gephyromochlus, Glanidiumcesarpintoi , Liosomadoras , Pseudepapterus, Trachelyopterina and some species of Tatia ; and (14) distal vesicle present on anterior margin of anal-fin rays in mature males (char. 3744: 0 → 1), convergent in Asterophysus , Pseudauchenipterus and Pseudepapterus .

Comparisons: Trachelyichthys is distinguished from remaining Auchenipteridae , except Ageneiosini , Trachelyopterichthys , Auchenipterus , Epapterus and Pseudepapterus by the anal fin being elongated, measuring at least half SL(vs.anal fin short to moderate, never surpassing one-third of SL) and, except for Trachelyopterichthys , Epapterus and Trachelyopterus coriaceus , by the absence of an adipose fin (vs. adipose fin present). It is further distinguished from all auchenipterines, except Spinipterus , by having the anterior fontanel rounded (vs. elliptical or elongated). It differs from Trachelyopterichthys by having the outer pair of mental barbels long, surpassing the posterior margin of the coracoid process (vs. outer pair of mental barbels never reaching posterior process of coracoid process), the posterior margin of the dorsal-fin spine bearing serration (vs. posterior margin of dorsal-fin spine smooth, lacking serration); interopercle thin and elongated (vs. interopercle large, plate shaped) and antorbital smooth, without any spine (vs. antorbital bearing spines). Finally, it differs from Epapterus by nuptial males having the anal-fin rays continuously distributed, without space between anterior modified and remaining rays (vs. anal fin with a space between modified anterior rays and remaining rays) and five branched dorsal-fin rays (vs. three branched dorsal-fin rays).

SUBTRIBE TRACHELYOPTERINA BLEEKER, 1858 (CLADE 82)

Tracheliopterini [ Trachelyopterina ] Bleeker, 1858a: 40 (type genus: Trachelyopterus Valenciennes, 1840 . Also in Bleeker, 1858b: 49, 250, 257).

Included genera: Spinipterus Akama & Ferraris, 2011 and Trachelyopterus Valenciennes, 1840 .

Diagnosis: Trachelyopterina is diagnosed by 26 molecular and two morphological synapomorphies. Non-exclusive: (1) coronoid process of anguloarticular deeper than dentary (char. 3601: 0 → 1), convergent in Auchenipterus ; and (2) posterior process of third epibranchial elongated, approximately the same length as its mesial portion (char. 3648: 0 → 1), reversed in Trachelyopterus porosus , Trachelyopterus aff. T. porosus and Trachelyopterus amblops , convergent in Auchenipterini (except Entomocorus and Pseudauchenipterus affinis ), Trachycorystes trachycorystes , Trachelyichthys (except Trachelyichthys sp.1 ), Auchenipterichthysthoracatus, Auchenipterichthys longimanus , Ageneiosus vittatus , Tympanopleura atronasus , Pseudotatia and Gelanoglanis .

GENUS SPINIPTERUS AKAMA & FERRARIS, 2011 View in CoL (CLADE 83)

Spinipterus Akama & Ferraris, 2011: 53 View in CoL View Cited Treatment (type species: Spinipterus acsi Akama & Ferraris, 2011 View in CoL ; type by original designation and monotypy. Gender masculine).

Included species: Spinipterus acsi Akama & Ferraris, 2011 View in CoL , Spinipterus sp. ‘oncinha’ Rossoni et al., undescribed.

Diagnosis: Spinipterus is diagnosed by three molecular and 13 morphological synapomorphies. Exclusive: (1) serration on dorsal margin of pectoral-fin spine present (char. 3705: 0 → 1). Non-exclusive: (2) dorsal projection of antorbital absent (char. 3515: 0 → 1), convergent in clade 98 of Auchenipterini ; (3) spines present on antorbital and ossified suborbital tubules (char. 3520: 0 → 1), convergent in Liosomadoras , Tatia caxiuanensis , Trachelyopterichthys and Trachycorystes trachycorystes ; (4) anterior fontanel restricted to frontals (char. 3541: 0 → 1), exclusive in Auchenipterinae , convergent in Centromochlus heckelii , Duringlanis perugiae , Tatia simplex , Tatia aff. T. simplex and Gelanoglanis pan ; (5) anterior fontanel rounded (char.3542: 0 → 1), convergent in small body-sized Tatia of clade 50, Tatia brunnea , Tatia simplex , Gelanoglanis pan and Trachelyichthys ; (6) lateroposterior portion of sphenotic distinctly concave (char. 3552: 0 → 2), convergent in Auchenipterini , some Ageneiosini , Trachelyopterichthys , Tatia reticulata and Trachelyichthys exilis ; (7) posterior process of posttemporal–supracleithrum posterodorsally oriented (char. 3561: 0 → 1), convergent in Centromochlinae (except Glanidium catharinensis , Glanidium sp. 1 RS and Glanidium sp. 2 RS), Auchenipterichthys , Entomocorus , Epapterus , Pseudauchenipterus nodosus , Trachelyichthys , Trachelyopterus amblops , Trachelyopterus insignis , Trachelyopterus cf. T. galeatus , some species of Ageneiosus and Tympanopleura ; (8) transcapular process at angle of ~45° relative to body axis (char. 3570: 0 → 1), convergent in Auchenipterini , Liosomadoras , Trachelyichthys (except Trachelyichthys decaradiatus ), Tatia intermedia , Tracheyopterus lucenai , Trachelyopterus cf. T. galeatus and Trachycorystes trachycorystes ; (9) premaxillary teeth straight (char. 3589: 0 → 1), convergent in Entomocorus , Gelanoglanis , Trachelyopterichthys , Gephyromochlus , some species of Tatia , Liosomadoras oncinus , Glanidium cesarpintoi , Tocantinsia and Trachycorystes trachycorystes ; (10) four free pterygiophores on dorsal fin (char. 3675: 2 → 3), convergent in Gelanoglanini , Glanidium cesarpintoi , Pseudepapterus hasemani , Tatia (except Tatia brunnea and Tatia musaica ), Trachelyichthys , Trachelyopterichthys and some species of Trachelyopterus ; (11) dorsal-fin spine short, less than one-sixth of SL (char. 3685: 0 → 1), convergent in Asterophysus , Epapterus and Pseudepapterus ; (12) three rows of serration on anterior margin of dorsal-fin spine (char. 3690: 0 → 2), convergent in Liosomadoras ; and (13) posterior margin of dorsal-fin spine smooth, without serration (char. 3693: 0 → 1), convergent in Asterophysus , Duringlanis perugiae , Epapterus , Gelanoglanis travieso , Glanidium cesarpintoi , Pseudepapterus , Pseudotatia , Tatia (except Tatia intermedia ), Tocantinsia¸ Trachelyopterichthys , Trachelyopterus amblops , Trachelyopterus insignis and Trachycorystes trachycorystes .

Comparisons: Spinipterus is somewhat similar externally to Trachelyopterus but of a smaller size and bearing distinctive features within the family. It can be diagnosed from remaining Auchenipteridae by having serrations on the dorsal and ventral margins of the pectoral-fin spine, exclusive in the family (vs. serrae in both dorsal and ventral margins of pectoral-fin spine present) and, except for Liosomadoras , by having three rows of serration on the anterior margin of the dorsal-fin spine (vs. one; or two in Trachelyopterichthys and Trachycorystes trachycorystes ). It is further distinguished from remaining auchenipterines, except Liosomadoras , Trachelyopterichthys and Trachycorystes trachycorystes , by having spines on the antorbital and ossified suborbital tubules; and, except Entomocorus and Trachelyopterus , by having fewer branched pelvic-fin rays, four or five (vs. more numerous branched rays on the pelvic fin, six to 16).

Remarks: Spinipterus was described based only on the holotype from Peru, but an additional specimen of Spinipterus acsi was found recently in a distinct locality, the Juruá River basin in Brazil ( Calegari et al., 2018). Based on the examination of both specimens and the CT scan images of the holotype, the configuration of the serration rows on the dorsal-and pectoral-fin spines was analysed, revealing distinctive features unique to this genus within Auchenipteridae . Although Akama & Ferraris (2011) have reported the presence of four rows of serration on the dorsal-fin spine, Spinipterus acsi has three rows of serration along the anterior and anterolateral margins of the spine, with one medial row and two others at an angle of 45° relative to the spine axis (see Calegari et al., 2018: fig. 4).

GENUS TRACHELYOPTERUS VALENCIENNES, 1840 View in CoL (CLADE 84)