Trichomycterus (Psammocambeva) fabioheppi, Costa & Barbosa & Katz, 2024

Costa, Wilson J. E. M., Barbosa, Maria Anaïs & Katz, Axel M., 2024, Two new species of Trichomycterus (Siluriformes: Trichomycteridae) from the Rio Itabapoana Basin, south-eastern Brazil, European Journal of Taxonomy 970, pp. 122-137 : 129-134

Trichomycterus (Psammocambeva) fabioheppi sp. nov.

urn:lsid:zoobank.org:act:22E77E5D-0C5D-4D9A-8DF8-732AB7302CDB

Figs 2D–F , 3–4 , 5A , Table 2

Diagnosis

Trichomycterus (Psammocambeva) fabioheppi sp. nov. is distinguished from all other species of Trichomycterus s. str. by having a unique morphology of the caudal fin, which is dorso-ventrally asymmetrical, with the dorsal portion longer than the ventral one, consequently making the ventral-most principal caudal-fin rays about half the length of dorsal-most ones ( Fig. 5A ; vs caudal fin dorso-ventrally symmetrical as in all other species of Psammocambeva , Fig. 5C–E , or dorsal portion just slightly longer than ventral one in larger specimens of Trichomycterus (Cryptocambeva) maracaya Bockmann & Sazima, 2004 , with dorsal-most and ventral-most principal caudal-fin rays about same length, Bockmann & Sazima, 2004: fig. 1). Trichomycterus (Psammocambeva) fabioheppi differs from all congeners, except species of the Psammocambeva beta-clade, by combining a shallow anterior outgrowth of the hyomandibula ( Fig. 2E ; vs never so shallow, e.g., Costa et al. 2022: fig. 4) and a long interopercle, about 90% of the hyomandibula longitudinal length ( Fig. 2E ; vs about 75% or less). Trichomycterus (Psammocambeva) fabioheppi is also distinguished from all species of the Psammocambeva beta-clade by having a rounded caudal fin (vs subtruncate or emarginate). Trichomycterus (Psammocambeva) fabioheppi differs from all other congeners of the Psammocambeva beta-clade, except T. largoperculatus and T. tantalus , by having a relatively short preopercle with a distinctive ventral expansion ( Fig. 2E ; vs a relatively longer, without distinctive ventral expansion). Trichomycterus (Psammocambeva) fabioheppi is also distinguished from T. largoperculatus and T. tantalus by possessing eight pectoral-fin rays (vs nine) and a broad dark brown stripe along lateral mid-line (vs no dark brown stripe).

Etymology

The specific epithet ‘ fabioheppi ’ honours the Brazilian herpetologist Fábio Hepp, researcher at the Institute of Biology, Federal University of Rio de Janeiro, who collected the type series of this species.

Type material

Holotype BRAZIL • 68.1 mm SL; Espírito Santo State, Mimoso do Sul Municipality, Serra das Torres , stream tributary to Rio Preto , Rio Itabapoana Basin ; 21°02′06″ S, 41°15′01″ W; ca 450 m a.s.l.; 6 Sep. 2010; F. Hepp, G.R. Silva, C.L. Dias and V. Sedano; UFRJ 12931 .

Paratypes BRAZIL • 8 ex., 27.4–49.7 mm SL; same data as for holotype; UFRJ 7939 • 3 ex. (C&S), 35.2–53.7 mm SL; same data as for holotype; UFRJ 12933 • 4 ex., 26.5–47.9 mm SL; same data as for holotype; CICCAA 07750 .

Description

GENERAL MORPHOLOGY. Morphometric data are in Table 2 . General morphology of trunk and head as described for T. (Cryptocambeva) berthalutzae sp. nov. Anus and urogenital papilla at vertical just anterior to middle dorsal-fin base. Eye moderately large, slightly smaller than exposed area of opercular patch of odontodes, dorsally positioned in head. Posterior nostril located at about ⅓ of distance between anterior nostril than orbital rim. Tip of maxillary and rictal barbels reaching between anterior and posterior regions of interopercular patch of odontodes, tip of nasal barbel reaching about midway between orbit and opercle or slightly before. Mouth subterminal. Jaw teeth pointed, slightly curved, arranged in irregular rows. Premaxillary teeth 41–83, dentary teeth 58–85. Odontodes conical. Opercular odontodes 17–19; interopercular odontodes 36–40. Branchiostegal rays 8.

FINS. Dorsal and anal fins subtriangular, anterior and posterior margins slightly convex; longest ray shorter than fin base. Total dorsal-fin rays 12 (iii + II + 7), total anal-fin rays 10 (iii + II + 5); anal-fin origin at vertical just anterior to dorsal-fin base end, through base of 5 th branched ray. Dorsal-fin origin at vertical through centrum of 18 th or 19 th vertebra; anal-fin origin at vertical between centrum of 22 nd or 23 rd vertebra. Pectoral fin subtriangular in dorsal view, posterior margin slightly convex, first pectoral-fin ray terminating in filament, its length about 20–25% of pectoral-fin length without filament. Total pectoral-fin rays 8 (I + 7). Pelvic fin subtruncate, its posterior extremity not reaching urogenital papilla, at vertical through middle of dorsal-fin base. Pelvic-fin bases medially separated by interspace about ⅓ or less pelvic-fin base width. Total pelvic-fin rays 5 (I + 4). Caudal fin rounded, dorso-ventrally asymmetrical, dorsal portion longer than ventral one. Total principal caudal-fin rays 13 (I + 11 + I), total dorsal procurrent rays 17–20 (xvi–xix + I), total ventral procurrent rays 13–16 (xii–xv + I).

LATERO-SENSORY SYSTEM. As described for T. (Cryptocambeva) berthalutzae sp. nov.

OSTEOLOGY ( Fig. 2D–F ).Anterior margin of mesethmoid gently concave, mesethmoid cornu subtriangular in dorsal view, tip rounded. Lacrimal oval, its largest length about ⅓ of sesamoid supraorbital length. Sesamoid supraorbital narrow, rod-like, longer than premaxilla largest length. Premaxilla sub-rectangular in dorsal view. Maxilla boomerang-shaped, slender, about so long as premaxilla, with minute posterior process. Autopalatine sub-rectangular in dorsal view when excluding posterolateral process, its shortest width about half autopalatine length, lateral margin about straight, medial margin sinuous. Latero-posterior process of autopalatine subtriangular, its length about ⅔ of autopalatine length. Metapterygoid subtrapezoidal, deeper than long, with distinctive projection on anterior margin. Quadrate robust, dorsoposterior outgrowth in close proximity to hyomandibular outgrowth. Hyomandibula long, anterior outgrow shallow, with pronounced concavity on dorsal margin. Opercle moderately elongate, depth of opercular odontode patch about 3 / 5 of dorsal articular facet of hyomandibula, dorsal process of opercle short and blunt. Interopercle long, its longitudinal length nearly equal to hyomandibula longitudinal length. Preopercle compact, with pronounced ventral expansion. Parurohyal robust, lateral process relatively elongate, pointed, slightly curved. Parurohyal head well-developed, with prominent anterolateral paired process. Middle parurohyal foramen oval, its largest length smaller than parurohyal posterior process. Posterior parurohyal process short, about half distance between anterior margin of parurohyal and anterior insertion of posterior process. Vertebrae 35 or 36. Ribs 12–14. Two dorsal hypural plates, corresponding to hypurals 4 + 5 and 3, respectively; single ventral hypural plate corresponding to hypurals 1 and 2 and parhypural.

COLOURATION IN ALCOHOL. Flank light yellowish grey with broad dark brown stripe along lateral mid-line interrupted on its posterior-most portion, longitudinal row of dark brown spots on dorsal portion, and small brown dots irregularly arranged on ventral portion. Dorsum light yellowish grey with middorsal row of small brown spots between nape and dorsal-fin origin. Dorsal and lateral portions of head brown, with light yellowish grey infraorbital zone. Ventral surface of head and trunk yellowish white. Jaws and nasal barbel brownish grey, maxillary and rictal barbels light grey. Fins hyaline, with faint brown spots on basal portion of unpaired and pectoral fins.

Distribution

Trichomycterus (Psammocambeva) fabioheppi is presently only known from the type locality, a small stream tributary to the Rio Preto, Rio Itabapoana Basin, at Serra das Torres, which is part of the Serra do Mar ( Fig. 3 ).

Figures

Fig. 2. Osteological structures. A–C. Trichomycterus (Cryptocambeva) berthalutzae sp. nov. (UFRJ 13252).D–F. Trichomycterus (Psammocambeva) fabioheppisp. nov.(UFRJ 12933).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. Parurohyal, ventral view. Larger stippling represents cartilaginous areas.

Fig. 3. Geographical distribution of trichomycterine catfishes in the Rio Itabapoana Basin.

Fig. 4. Trichomycterus (Psammocambeva) fabioheppi sp. nov., holotype (UFRJ 12931), 68.1 mm SL. A. Left lateral view. B. Dorsal view. C. Ventral view.

Fig. 5. Caudal fin morphology in species of Psammocambeva Costa, 2021, left lateral view. A. Trichomycterus (Psammocambeva) fabioheppi sp. nov., holotype (UFRJ 12931), 68.1 mm SL. B. Trichomycterus longibarbatus Costa, 1992, topotype (UFRJ 3368), 52.9 mm SL. C. Trichomycterus travassosi (Miranda Ribeiro, 1949) (UFRJ 5190),57.2 mm SL.D. Trichomycterus puriventris Barbosa & Costa, 2012 (UFRJ 5398), paratype, 76.9 mm SL. E. Trichomycterus largoperculatus Costa & Katz, 2022, holotype (UFRJ 6987), 77.8 mm SL.