Pseudobunocephalus timbira, Leão & Carvalho & Reis & Wosiacki, 2019

Leão, Manuela Dopazo V., Carvalho, Tiago P., Reis, Roberto E. & Wosiacki, Wolmar B., 2019, A new species of Pseudobunocephalus Friel, 2008 (Siluriformes: Aspredinidae) from the lower Tocantins and Mearim river drainages, North and Northeast of Brazil, Zootaxa 4586 (1), pp. 109-126 : 111-116

Pseudobunocephalus timbira , new species

( Figs. 1 , 2 ; Tables, 1, 2)

urn:lsid:zoobank.org:act:392F95E0-86E1-4386-8779-C4F71098DBCC

Acanthobunocephalus sp. nov. 3 — Cardoso, 2008: 166 [unpublished phylogenetic study, listed as an undescribed species].

Holotype. MPEG 21057 , 31.8 mm SL, Brazil, Maranhão, Alto Alegre do Pindaré, Jundiá Creek, Mearim River basin, 3°39’14”S 45°42’19”W, T. M. S. Freitas, 11 June 2011.

Paratypes. All from Brazil . INPA 6519 , 1 , 18.4 mm SL, Pará, Itupiranga, Jatobal Creek 1 km upstream its mouth, Tocantins River basin, 4°28'S 49°27'W , INPA staff, 15 Nov 1981 . INPA 6520 , 3 , 23–26 mm SL, Pará, Itupiranga, Jatobal Creek, Tocantins River basin, 4°28'S 49°27'W , INPA staff, 8 Jul 1982 . INPA 6532 , 4 , 22.7 – 23.1 mm SL, Pará, Itupiranga , Tocantins River, Tocantins River basin ; INPA staff, 15 Jul 1980. MCN 19274 , 2, 25.7– 29.2 mm SL, Tocantins, São Sebastião do Tocantins, Lake at Fazenda Ozara , Tocantins River Basin , 05°16'04"S 48°10'20"W, A. Cardoso & staff, 20 Sep 2010 . MCP 54089, 5 , 19.2 – 25.5 mm SL, Pará, Marabá, Tapirapé River upstream Bacaba base , REBIO Tapirapé, Tocantins River basin, 5°40’7”S 50°18’49”W, I. Fichberg & J. Muriel- Cunha, 3 Aug 2008 . MCP 54090, 5 , 23.6 – 33 mm SL, Pará, Marabá, Grotão do Wilson Creek , Trilha Bacaba , REBIO Tapirapé, Tocantins River basin, 5°40’28”S 50°19’21”W, I. Fichberg & J. Muriel-Cunha, 8 Aug 2008 . MHNG 2551.010 , 10 , 1 c&s, 23.7–24.9 mm SL, Pará, São João do Araguaia, small tributary to Tocantins River 12 km from São João do Araguaia , Tocantins River basin, approx. 05°21'S 48°47'W, R. Stawikowski, 18 Sep 1990 . MPEG 30384 , 1 , 22.7 mm SL, Pará, Bom Jesus do Tocantins, Flexeiras River , Tocantins River basin, 5°15’35”S 48°59’35 W, C. Costa, 20 May 2012 . MPEG 37432 , 1 , 28.8 mm SL: colleted with holotype . MPEG 38466 , 5 , 1 c&s, 21.6–26.9 mm SL, Pará, Marabá, Tapirapé River upstream Bacaba base , REBIO Tapirapé, Tocantins River basin, 5°40’7”S 50°18’49”W, I. Fichberg & J. Muriel-Cunha, 3 Aug 2008 . MPEG 38467 , 5 , 1 c&s, 23.7–28 mm SL, Pará, Marabá, Grotão do Wilson Creek , Trilha Bacaba , REBIO Tapirapé, Tocantins River basin, 5°40’28”S 50°19’21”W, I. Fichberg & J. Muriel-Cunha, 8 Aug 2008 . MZUSP 105309 , 49 , 17.9 – 32.5 mm SL, Pará, Marabá, Tapirapé River upstream Bacaba base , REBIO Tapirapé, Tocantins River basin, 5°40’7”S 50°18’49”W, I. Fichberg & J. Muriel-Cunha, 3 Aug 2008 . MZUSP 105368 , 51 , 22.0– 33.4 mm SL, Pará, Marabá, Grotão do Wilson Creek , Trilha Bacaba , REBIO Tapirapé, Tocantins River basin, 5°40’28”S 50°19’21”W, I. Fichberg & J. Muriel-Cunha, 8 Aug 2008 .

Diagnosis. Pseudobunocephalus timbira can be distinguished from all congeners by having the second hypobranchial and the third basibranchial cartilaginous (vs. ossified). Additionally, it can be dintinguished from P. lundbergi by the following putative apomorphic features within Pseudobunocephalus : posterolateral process of premaxilla present ( Fig. 2C vs. absent); bony knobs in dorsal lamina of Weberian apparatus absent ( Fig. 2B vs. present, Fig. 3A, B ); distal end of posterior margin of 5th parapophysis not enlarged ( Fig. 2B vs. enlarged, Fig. 3A, C ,); three pairs of ribs ( Fig. 2B vs. four or five, Fig. 3A ); infraorbital sensory canal entering neurocranium via frontal ( Fig. 2A vs. via sphenotic, Fig. 3A ).

It is distinguished from P. bifidus and P. iheringii by having a gracile body not surpassing 34 mm SL (vs. robust body, reaching 52 and 59 mm SL, respectively); by having the posterior margin of cranial fontanel concave ( Fig. 2A vs. posterior margin somewhat straight with parieto-supraoccipital extending anteriorly, Fig. 3D ); by conspicuously knobby skull ornamentation on its dorsal surface ( Fig. 2A, B vs. skull knobs slightly pronounced, Fig. 3D, E ); by having Weberian ventral blade of hemal canal opened ( Fig. 2C vs. closed, Fig. 3F ) and by the absence of serrations on the proximal portion of the anterior margin of pectoral-fin spine ( Fig. 2A, C vs. serrations covering entire anterior margin of the pectoral spine, Fig. 3 D–I).

Additionally, it can be distinguished from P. amazonicus , P. rugosus and P. quadriradiatus , by having the posterolateral mental barbels with at least one fleshy lobe located proximally along the posterior margin (vs. posterolateral mental barbel simple, not having fleshy lobes).

It also differs from P. amazonicus and P. rugosus by having five branchiostegal rays ( Fig. 2C vs. four, Fig. 4 D– I). It also can be distinguished from P. amazonicus by having the contact of hyomandibula cartilage with neurocranium limited to the sphenotic (vs. extending to both sphenotic and pterotic); by having the ventral blade of Weberian apparatus open ( Fig. 2C vs. closed, Fig. 3I ) and by anterior exit of hemal canal in abdominal vertebra (vs. in complex vertebra); from P. rugosus by coloration of proximal portion of caudal fin similar to rest of caudal fin (vs. clear patch) and from P. quadriradiatus by the total number of pectoral fin-rays six (vs. five).

Description. Dorsal, lateral and ventral views of holotype shown in Figure 1 . Maximum body length observed 33.4 mm SL. Morphometric data for holotype and 14 paratypes summarized in Table 1 . Head and anterior body depressed. Anterodorsal profile of body ascending from tip of snout to dorsal-fin origin. Posterodorsal profile of body descending from dorsal-fin to base of caudal fin. Ventral body profile convex from mouth to insertion of pelvic fin and concave from this point to anal-fin origin. Caudal peduncle rounded, long and slender.

Knobs on dorsal surface of skull approximately equal in size. Eye small and positioned dorsolaterally. Skin covering eye dense and pale. Anterior nostril tubular located at tip of snout. Posterior nostril without flap or barbel, located anteromedially to eye. Mouth terminal, upper and lower jaws equal. Maxillary barbel simple, beginning on mouth corner and its posterior end surpassing pectoral-fin spine insertion. Anteromedial mental barbel simple and posterolateral mental barbel bifid with one or more fleshy lobe proximally along posterior margin. Skin of trunk covered with small unculiferous tubercles in longitudinal rows; mid-dorsal row well defined and three or four welldefined rows on each side of caudal peduncle. Several poorly-defined rows ventrally.

Anterior margin of mesethmoid straight, not anterolaterally projected ( Fig. 2A ), its anterior surface smooth. Posterior dorsal margin of mesethmoid contiguous with frontal. Ethmoid cartilage separated from articular facet of palatine. Lateral margin of frontal concave forming eye orbit and posterior margin not contacting the parietosupraoccipital. Epyphiseal bar absent ( Fig. 2A ). Posterior portion of cranial fontanel opened between frontals and its parieto-supraoccipital margin concave. Laminar process in lateral margin of pterotic present. Pterotic with lateral margin rounded. Supratemporal fossa present. Posterior process of parieto-supraoccipital truncated. Premaxilla with posterolateral process and ventral surface smooth. Teeth on premaxilla through entire surface. Dentary teeth restricted to broad tooth patch near symphysis of lower jaw. Ascending process of Meckel’s cartilage contacting main portion of this cartilage. Coronomeckelian bone present. Hyomandibula fused to preopercle. Posterodorsal portion of hiomandibula not associated to preopercular-mandibular laterosensory canal. Supraopercle absent. Cartilaginous articulation or joint of hyomandibula with neurocranium restricted to sphenotic. Opercular condyle of hyomandibula, directed posteroventrally. Metapterygoid present, not contacting hyomandibula or quadrate. Entopterygoid present. Posterior margin of autopalatine bifurcated, bearing two separate terminal cartilages. Opercle L shaped, posterior arm longer than ventral arm. Interopercle present, not attached to opercle. Dorsal hypohyal absent. Anterior and posterior ceratohyal contact with equal size. Anterior ceratohyal contacting posterior ceratohyal by serrated suture. Posterior ceratohyal with foramen, its posterior margin tappered. Interhyal absent. Five branchiostegal rays. Urohyal present, with medial foramen. Fourth pharyngobranchial absent. First hypobranchial ossified and second cartilaginous. Second basibranchial ossified and third basibranchial cartilaginous. Third epibranchial not bearing uncinate process. Fourth ceratobranchial elongated. Gill rakers absent on all arches. Pharyngeal teeth on upper tooth plate; two or three rows of teeth on fifth ceratobranchial.

Incomplete lateral line with simple tubules. Lateral line canal truncated just posterior to parapophyses of fifth vertebra and anterior to dorsal-fin origin, some specimens with isolated pores scattered more posteriorly, but never connected to main lateral-line canal. Nasal not ossified. Infraorbital canal limited to a single ossified tubule or none. Preopercle canal on preopercle with three pores. Mandibular canal interrupted anteriorly. Anterolateral branch of pterotic canal absent.

Dorsal lamina of Weberian apparatus extending to dorsal surface of body with anterior portion of lamina with dorsal concavity on its anterior margin ( Fig. 2B ). Reduced contact of parapophysis of fourth vertebra with parapophysis of fifth vertebra. Parapophysis of fifth vertebra larger than parapophysis of fourth vertebra and anteriorly oriented. Distal portion of fifth parapophysis not expanded. Free vertebrae without horizontal transverse process. Hemal and neural spine anteroposteriorly expanded. Hemal spines contacting anal-fin pterygiophores simple. Total vertebrae 35. Three pairs of ribs.

Dorsal fin i,4; spinelet absent; posterior margin of last dorsal-fin ray not adnate to body. Anterior nuchal plate and supraneural absent. Middle nuchal plate ornamented with single bony knob. Pectoral fin I,5. Pectoral-fin spine curved along its main axis. Serrations of pectoral-fin only middle portions to distal margin. Posterior margin of pectoral-fin spine with entirely serrated. Posterior scapulo-coracoid process of pectoral girdle extends slightly past posterior cleithral process in lateral view. Pelvic fin i,5 or i,4,i; first and second branched rays longest not reaching anal-fin origin; pelvic splint absent. Anal fin with seven or eight soft rays, anal-fin membrane not adnate to body. Caudal fin i,8,i; rounded plus one upper and one lower procurrent rays. Five rays associated with upper and five rays associated with lower lobe of caudal skeleton. Lowermost and uppermost caudal-fin rays unbranched, those slightly shorter than following branched rays. Adipose fin absent.

Color in alcohol. Dorsal and lateral surface of head and body mostly light to dark brown contrasting with scattered lighter areas. Dermal tubercles lighter than remaining areas. Ventral surface of head and trunk light yellow, with darker pigmentation on caudal peduncle. All fins hyaline with patterns of scattered dark brown chromatophores. Caudal-fin base with dark brown spot.

Distribution. Pseudobunocephalus timbira is known from small tributaries of the lower Tocantins and Mearim river basins in Maranhão, Pará and Tocantins states, Brazil ( Fig. 4 ).

Ecological notes. The new species was collected in small and slow flowing streams running over sand or muddy bottom. The type locality in the Mearim River basin ( Fig. 5 ) is a sediment rich tributary with moderate marginal and submersed vegetation.

Etymology. The specific epithet refers to the Timbira people who are the indigenous groups that live in the south of Maranhão, east of Pará and north of Tocantins, area of occurrence of the new species.

Conservation status. Pseudobunocephalus timbira is currently known from an Extention of Occurrence (EOO) larger than 48,000 square kilometers and no significative threats to the species were detected. In addition, part of the known population occurs inside a protected biological reserve (Reserva Biológica do Tapirapé). For these reasons, Pseudobunocephalus timbira can be categorized as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria ( IUCN Standards and Petitions Subcommittee, 2017).

Figures

FIGURE 1. Dorsal, lateral and ventral views of Pseudobonocephalus timbira, holotype, MPEG 21057, 31.8 mm SL, Brazil, Maranhão, Alto Alegre do Pindaré, Jundiá Creek, Mearim River basin.

FIGURE 2. HRXCT model of skull and anterior body of Pseudobunocephalus timbira, MCN 19274, paratype, 29.2 mm SL. (A) dorsal view, (B) lateral view, and (C) ventral view. ach = anterior ceratohyal; bp = basipterygium; br = branchiostegal rays; cl = cleithrum; cv = complex vertebrae; den = dentary; dp = proximal portion of pectoral-fin spine; fr = frontal; hc = hemal canal; hm = hyomandibula; io = infraorbital; me = mesethmoid; mnp = middle nuchal plate; mx = maxilla; tf = temporal fontanel; pcl = posterior process of cleithrum; pnp = posterior nuchal plate; pfr = pectoral-fin rays; pfs = pectoral-fin spine; pll = posterior lateral line tubules; pmx = premaxilla; po = preopercle; pp = proximal portion of pectoral-fin spine; psc = posterior process of scapulocoracoid; pso = parietosupraoccipital; pto = pterotic; pv5 = parapophysis of fifth vertebra; puh = urohyal; r = ribs; sc = scapulocoracoid; scl = supracleithrum; spo = sphenotic; v6 = sixth vertebra; vh = ventral hypohyal. Limits between selected bones are highlighted in black.

FIGURE 3. HRXCT model of skull and anterior body of selected Pseudobunocephalus species. (A) dorsal view, (B) lateral view, and (C) ventral view of P. lundbergi ANSP 168813, 30.3 mm SL. (D) dorsal view, (E) lateral view, and (F) ventral view of P. iheringii UFRGS 7175, 36.9 mm SL. (G) dorsal view, (H) lateral view, and (I) ventral view of P. amazonicus MCP 35751, 30 mm SL. Limits between selected bones are highlighted in black.

FIGURE 4. Localities of species of Pseudobunocephalus. Black triangles: P. quadriradiatus, white triangles: P. amazonicus, black circles: P. rugosus, white circles: P. iheringii, black squares: P. bifidus, white squares: P. lundbergi, Star: P. timbira, Red Star: Holotype of P. timbira.

FIGURE 5. Jundiá Creek at the type locality for Pseudobunocephalus timbira, tributary of Mearim River drainage, Alto Alegre do Pindaré, Maranhão State, Brazil.