Batrochoglanis castaneus, Shibatta, 2019

Shibatta, Oscar A., 2019, New species of bumblebee catfish of the genus Batrochoglanis Gill, 1858 (Siluriformes: Pseudopimelodidae) from the Aripuanã River basin, Mato Grosso, Brazil, Zootaxa 4674 (2), pp. 243-263 : 244-256

Batrochoglanis castaneus , new species

( Figures 1–14 , Table 1 )

urn:lsid:zoobank.org:act:0BF7C8B5-F053-4D05-AADC-75DADC1FFFE8

Holotype. INPA 8059 , 58.3 mm SL, Igarapé do Castanhal , Aripuanã River basin, Equipe de Ictiologia do INPA, 22 Nov. 1976.

Paratypes. Brazil. Mato Grosso. INPA 8054 , 1 , 54.3 mm CP, Igarapé do Castanhal, Aripuanã River basin, Equipe de Ictiologia do INPA, 22 Aug. 1976 . INPA 58786 , 13 (1 C&S), 25.5–50.7 mm CP, same data as the holotype . MZUEL 20113 , 3 (1 C&S), 50.8–55.8 mm SL, same data as the holotype .

Diagnosis. Batrochoglanis castaneus differs from its congeners, except B. raninus and B. transmontanus , by the dark brown color of the body, with a light brown band on the nape, a light blotch immediately posterior to the vertical through the terminus of the dorsal-fin base, and on the terminus of the adipose fin (vs. body mottled with dark brown spots in B. villosus and B. acanthochiroides ), and caudal fin hyaline with a dark brown stripe (vs. caudal fin completely dark in B. melanurus ). Batrochoglanis castaneus differs from B. raninus by the longer maxillary barbel (131.8%±10.1 of HL vs. 87.7%±9.3, p <0.01), longer prepelvic length (57.4%±0.7 of SL vs. 55.9%±1.4, p<0.01), greater prepectoral length (31.5%±1.6 of SL vs. 29.5%±1.04, p<0.01), anal-fin base length (12.0±0.5 vs. 13.4±0.92, p<0.01), and head depth (31.1±2.5 vs. 34.6±2.2, p<0.01). The new species differs from B. transmontanus by the longer caudal-fin dorsal lobe, presence of translucent spot or stripe on pelvic, dorsal, and anal fins, longer maxillary barbel length (131.8%±10.1 of HL vs. 87.7%±9.3, p<0.01), longer pectoral-fin spine length (21.0%±1.7 of SL vs. 16.1%±0.85, p<0.01), longer dorsal-fin spine length (16.5%±1.1 of SL vs. 12.1±1.6, p<0.01), greater eye diameter (12.2%±1.3 of HL vs. 7.7%±1.0, p<0.01), smaller head depth (31.1%±2.5 of HL vs. 37.4±3.8, p<0.01), and larger mouth width (71.2%±3.9 of HL vs. 63.2%±6.0, p<0.01).

Description. Body proportions presented in Table 1 . Dorsal profile slightly convex, almost straight from tip of snout to terminus of adipose fin. Ventral profile slightly convex from edge of mandible to beginning of caudal fin. Head larger than wide. Profile of head trapezoidal in dorsal view, greater width at cleithrum bulge. Gill opening wide. Gill rakers simple, without branching or bifurcations; epibranchials 2(3), 3(6*) rakers; epibranchial-ceratobranchial cartilage 1(9*) raker, ceratobranchial 6(5), 7(7*) rakers. Maxillary barbel surpassing the opercular border, but not reaching vertical through beginning of dorsal fin. External mental barbel surpassing base of pectoral fin. Dorsal fin trapezoidal, when adpressed not reaching adipose fin; I+6(9*) rays. Dorsal-fin spine sharp-pointed, anterior and posterior margins smooth, without serrae or denticuli. Adipose fin elongated with posterior end free and angled. Pectoral fin triangular, when adpressed not reaching ventral fin, I+6(9*) rays. Pectoral-fin spine covered by thin skin, serrated on both sides, antrorse and retrorse serrae on anterior margin and retrorse serrae on posterior margin; anterior serrae a little shorter than posterior ones. Pelvic fin triangular, with rounded border, terminus at vertical through base of fifth branched ray of dorsal fin, reaching origin of anal fin when adpressed; i+5(9*) rays. Anal fin semi-circular, its base length similar to adipose-fin base length; ii(3*), iii(6) + 6(1), 7(6), 8(2*) rays. Caudal fin with upper rays longer; 8(8*) rays in upper lobe, 6(4*), 7(4) rays in ventral lobe. Postcleithrum process elongated with little blunted point. Lateral line incomplete, reaching vertical through anterior third of adipose fin. Axillary pore absent.

Osteological features. Cranial roof approximately triangular ( Fig. 2a ). Surface irregular, with several small rounded depressions. A single and large fontanel between mesethmoid and frontals; epiphyseal bar absent. Mesethmoid in the anterodorsal region of neurocranium, bifurcated anteriorly, with two cornua, ventrally attached by ligaments to the premaxilla. Lateral ethmoid broad, irregular shaped, medially articulated to mesethmoid, laterally articulated to autopalatine condyle. Ethmoid cartilage broad, located on the anterior region of lateral ethmoid and laterally to mesethmoid. Frontal bone anteriorly narrow and posteriorly expanded, sutured to sphenotic and parietosupraoccipital bones; frontals separated by large fontanel anteriorly. Sphenotic bone longer than wide, sutured to frontal, parieto-supraoccipital and pterotic bones. Pterotic approximately same size as sphenotic; sutured to sphenotic, parieto-supraoccipital and epiotic bones. Sphenotic and pterotic articulated to hyomandibula on their ventral surfaces. Extrascapula approximately half size of pterotic, located on posterior region of neurocranium, articulated to pterotic and parieto-supraoccipital. Sphenotic, pterotic and epiotic forming the posterolateral roof of skull. Parieto-supraoccipital a little wider than long, forming the posteromedian surface of cranial roof, sutured to frontals, sphenotics, pterotics, and epiotics. A single parieto-supraoccipital fontanel, posteriorly placed, ellipsoid shaped. Parieto-supraoccipital crest extending posteromedially, triangular shaped, posteriorly pointed, not touching anterior nuchal plate. Nasal bone tubular, slightly curved, laterally placed to mesethmoid.

Cranial floor surface less ornamented with rounded depressions than roof ( Fig. 2b ). Vomer absent. Mesethmoid articulated medially to lateral ethmoid. Parasphenoid narrow anteriorly and wider posteriorly; anteriorly sutured with mesethmoid and lateral ethmoid; laterally articulated to orbitosphenoid and pterosphenoid, and posteriorly with prootic and basioccipital. Orbitosphenoid large, lateral wall dorsally sutured to frontals and anteriorly with synchondral joint to lateral ethmoid. Pterosphenoid irregular shaped, posterior to orbitosphenoid, lateral to parasphenoid, and medially to sphenotic. Prootic large, latero-posteriorly sutured with pterotic; posteriorly with exoccipital. Wide foramen for trigeminofacialis nerve between pterosphenoid anteriorly, prootic posteriorly, and parasphenoid medially. Exoccipital forming posterior corner of neurocranium lateral to basioccipital. Basioccipital forming the posterior region of cranial floor, posteriorly articulated to first vertebra. Epiotic (visible only in posterior view) triangular-shaped, posteroventral to extrascapula. Supraoccipital process ventral region with a V -shaped gutter. Lateral line with one ossified anteriormost canal near first pore.

First infraorbital irregular shaped, a thin curved point anteriorly, posterolateral and medial processes bearing a canal and pore of lateral line, and a posterior elongated process. Second infraorbital small, elongated, slightly curved. Third infraorbital straight, elongated, lateral to eye. Fourth infraorbital larger, angular, almost 90 degrees curved ( Fig. 2 ).

Posttemporal-supracleithrum ( Fig. 2 ) well-developed, elongated, attached to pterotic and extrascapula anteriorly, and posteriorly to anterior process of parapophysis of fourth vertebra. Ventrally, an elongated cylindrical ossified transcapular ligament attached to basioccipital by a ligament. Ventrolateral limb attached to the upper limb of cleithrum.

Premaxilla longer than wide, with lateral point projecting posteriorly; ventrally bearing tooth plate with four irregular rows of small conical teeth turned slightly backward ( Fig. 2 ). Maxilla small, approximately wing-shaped, with two proximal rounded heads (dorsal and ventral condyle), medially articulated to autopalatine. Autopalatine ( Fig. 3 ) elongated anteroposteriorly, spoon-shaped, with a dorsal keel in the posterior tip; latero-anteriorly articulated to the maxillary bone, medially to lateral ethmoid by a rounded articulation facet.

Dentary ( Fig. 4 ) long and straight, slightly deep posteriorly bearing the dorsal coronoid process; three irregular series of small conical teeth on dorsal surface. Six preoperculomandibular laterosensory branches (pm1-pm6) along lateroventral surface of dentary. Angular, articular, and retroarticular bones fused, horizontally elongated, articulated with dentary anteriorly and posteriorly attached to quadrate by ligaments. Coronomeckelian bone on medial surface, small, irregular shaped, posterodorsally articulated with horizontally elongated Meckelian cartilage.

Suspensorium with broad hyomandibula anteriorly sutured to irregularly shaped metapterygoid, and ventrally to quadrate ( Fig. 5 ); dorsally articulated to pterotic and sphenotic, and posteriorly with opercle. Metapterygoid anterior region wider and with three pointed processes (basal, anterior, and ectopterygoid processes). Quadrate somewhat triangular, articulated by cartilage to hyomandibula and metapterygoid. Quadrate with a fenestra in ventral region to articulate with posterior dorsal projection of anguloarticular. Entopterygoid ( Fig. 2b ) irregular shaped, with a sharp anterolateral process, articulated to ectopterygoid anteriorly and attached to metapterygoid by ligaments posteriorly. Ectopterygoid ( Fig. 2b ) comma-shaped, attached to posteroventral surface of autopalatine and posteromedially articulated to entopterygoid.

Opercle ( Fig. 5 ) large, somewhat triangular, posteriorly rounded, anteriorly articulated to hyomandibula, and anteroventrally to interopercle. Preopercle long and thin, sutured along posterior margin of hyomandibula and quadrate. Interopercle triangular, slightly concave anteriorly, articulated to opercle posteriorly and preopercle anteriorly.

Hyoid arch ( Fig. 6 ) with small triangular ventral hypohyal, well developed anterior ceratohyal and triangular posterior ceratohyal. Dorsal hypohyal absent. Nine branchiostegal rays articulated with hyoid arch; six with anterior ceratohyal, one with interceratohyal cartilage, and two with posterior ceratohyal. These two posteriormost branchiostegal rays largest and posteriorly expanded. Parurohyal located between ventral hypohyals; anterior portion blunt, lateral process like triangular wing, medially with laminar process and short pointed posterior process.

Pharyngobranchial 1 absent. Pharyngobranchial 2 cartilaginous, elongated, articulated with epibranchials 1 and 2, and pharyngobranchial 3. Pharyngobranchial 3 elongated, ossified, somewhat triangular, with wider posterior region. Pharyngobranchial 4 rounded, ossified, with a tooth plate with irregular five rows of conical teeth. Epibranchial 1 rod-like, with a posterodorsal uncinate process, and a row of five elongated rakers. Epibranchial 2 slightly curved, with one row of elongated rakers. Epibranchial 3 rod-like with a posterior uncinate process, with two rows of small conical rakers. Epibranchial 4 broad, slightly convex anteriorly and posteriorly; toothless. First and second ceratobranchials supporting a single row of elongated rakers. Third and fourth ceratobranchial with two rows of rakers. Fifth ceratobranchial medially expanded, supporting tooth plate dorsally, with conic teeth in approximately six irregular rows. Hypobranchial 1 ossified, laminar, trapezoid, with medial margin cartilaginous; laterally to basibranchial 2. Hypobranchial 2 ossified, laminar, ovoid, with posterior margin cartilaginous; laterally to basibranchial 3. Hypobranchial 3 entirely cartilaginous, trapezoid, laterally to posterior cartilaginous tip of basibranchial 3. Hypobranchial 4 absent. Basibranchial 1 absent. Basibranchial 2 ossified, nearly spoon-shaped, with anterior cartilaginous tip, and posteriorly sharing cartilage with basibranchial 3. Basibranchial 3 small, elongated, ossified, with a small posterior cartilaginous tip. Basibranchial 4 pentagonal shaped, entirely cartilaginous ( Fig. 7 ).

Cleithrum with a dorsoventral laminar bone forming a cylindrical crest anteriorly; right and left sides a little separated medially; posteriorly articulated with coracoid ( Fig. 8 ). Posterior cleithral process elongated, with a little blunt point, not surpassing anterior dorsal process of cleithrum posteriorly. Anterior and posterior dorsal process of vertical limb of cleithrum pointed; anterior larger than posterior. Coracoid wide, laminar; sutured to cleithrum anterolaterally; right and left coracoid interdigitated medially with strong serrations. Coracoid process triangular, articulated with pectoral-fin spine. Mesocoracoid arch thin. Radials elongated; first cartilaginous, posterior three ossified, articulated with six divided rays. Pectoral-fin spine serrated, anterior serrae antrorses (0(1*), 2(3), 3(1), 4(4), 5(1) serrae) and retrorses (2(1), 5(2), 6(2), 8(2), 10(1), 12(1), 13(1) serrae), total of 7(1), 9(3), 10(2), 12(2), 13(1*), 14(1); posterior serrae retrorse, 6(1), 8(4), 10(2), 11(3*).

Pelvic girdle composed of a wide basipterygium, with two elongated anterior processes, the medial one (internal) wider and shorter than the lateral (external) ( Fig. 9 ). Cartilage in lateral (including the lateral process), medial, and posterior sides, and on the tip of external anterior process. Six rays articulated to lateral cartilage.

Axial skeleton composed of three bones of Weberian apparatus, complex vertebra composed of vertebrae 1, 4 and 5; 28(6) or 29(3) free vertebrae; one compound caudal vertebra; and 5(1), 6(2), 7(6) or 8(1) ribs, with first rib attached to sixth centrum. Tripus triangular, with the longest tip pointed anteriorly, medial-posteriorly articulated with os suspensorium. Intercalarium slightly fusiform, little wrapped. Scaphium curved spoon-shaped, with the concave region dorsal. Claustrum small, concave. Complex vertebra with anterior and posterior parapophysis of fourth vertebra and parapophysis of fifth vertebra ( Fig. 10 ). Os suspensorium in the ventral region of parapophysis of fourth vertebra, lateral to centrum of complex vertebra, articulated with tripus. The anterior process of parapophysis of fourth vertebra lateroposteriorly curved, anteriorly articulated to posttemporal-supracleithrum.

Dorsal fin with spinelet, one spine, and six divided rays supported by five wide proximal radials ( Fig. 11 ). Dorsal-fin spine smooth anteriorly and posteriorly, with no serrae or denticuli. Anterior nuchal plate triangular, anteriorly pointed. Middle nuchal plate trapezoidal, and posterior third paired and rectangular. Dorsal-fin rays articulated to wide pterygiophores by cartilages. Third to seventh pterygiophores broad, only narrowly separated.

Anal fin composed of proximal radials, distal radials, and ii(3*), iii(6) + 6(1), 7(6), 8(2*) rays ( Fig. 12 ). Proximal radials elongated, pointed, with laminar process; the last one rectangular shaped. Distal radials rounded, first two and last cartilaginous, others ossified and anteriorly cartilaginous. First anal-fin ray rudimentary, usually hidden by the skin.

Caudal fin skeleton ( Fig. 13 ) composed of a plate formed by parhypural + hypurals 1 and 2, another plate formed by hypurals 3 and 4, hypural 5 free, and a pleurostile fused to compound centrum. A free elongated epural, slightly curved, with distal portion wider. Opisthural cartilage slightly rounded. A laminar secondary hypurapophysis fused to the anterodorsal region of hypural 2 (type C hypurapophysis sensu Lundberg & Baskin, 1969). Eighteen dorsal procurrent rays; i,7,6,i principal rays; 11 ventral procurrent rays.

Laterosensory system ( Fig. 14 ). Head sensory canals composed of single pores. Supraorbital sensory canal continuous with five pores (s1, s2, s3, s6 (epiphyseal branch), and s8 (parietal branch)) and connected to otic and infraorbital sensory canals posteriorly. Left and right epiphyseal branches (s6) never fused medially. S4 and s5 branch and pore absent. Presence of s7 pore (postorbital) in two of eight examined specimens. Otic sensory canal short, without pores, anteriorly continuous with supra- and infraorbital sensory canals, and posteriorly with postotic sensory canal. Postotic (or temporal) sensory canal located between posterior limit of otic sensory canal and anterior limit of lateral line, with two branches (po1, and po2). First postotic branch (po1) fused to a posteriormost branch of preoperculomandibular sensory canal (pm11), forming po1+pm11 complex pore. Infraorbital sensory canal with six branches (i1-i6). Preoperculomandibular sensory canal with 11 pores; pm1 not fused to its opposite counterpart branch. Lateral-line sensory canal continuous with postotic sensory canal and extending to vertical through origin of anal fin. First lateral-line pore immediately posterior to vertical through posterior margin of opercular bone. Lateral line with 18(1), 20(3), 21(2*) pores on the left side, and 18(1), 19(2), 20(1), 22(1), and 24(1*) pores on the right side.

Rostral line with one neuromast located between anterior nostrils; nasal line with four neuromasts, in front of anterior nostril; anterior line in the occipital region, after pore S8, with two neuromasts; dorsal trunk line anterior to dorsal fin, with two neuromasts; mandibular line with four neuromasts in the ventral region of head, forming an arch between i4 and i5 pores and pm6 and pm7; supratemporal accessory line located posteriorly to po2, with 2 neuromasts.

Color in alcohol. Head and trunk dark brown. Light brown stripe along nape, running from right to left pectoral fins. Light brown spots above lateral line soon after vertical through dorsal fin terminus, and light brown stripe crossing caudal peduncle transversely, between adipose and anal fins. Light brown saddle-shaped spot sometimes between adipose and caudal fins. Adipose fin dark brown with light brown spot on the anterior and posterior region. Dorsal fin dark brown, with hyaline stripe on top and medially on five last rays. Pectoral and pelvic fins dark brown with hyaline spot on base and margin. Anal fin with dark stripe on base and middle. Posterior cleithral process light brown. Caudal fin hyaline, with dark brown spots scattered on first two thirds, and broad dark brown band on posterior third. Ventral region light brown. ( Fig. 1 ).

Distribution. Known only from the type-locality, Igarapé do Castanhal, Aripuanã River basin, state of Mato Grosso, Brazil. No coordinate or municipality was recovered from the labels, which did not enable determination of a specific site of the type-locality. The collecting site is tentatively estimated at 59 o 27’34”W, 10 o 10’00”S in SpeciesLink (http://splink.cria.org.br/), which is near Aripuanã City. However, in the Aripuanã River basin, a river called Igarapé Castanhal occurs in the Colniza municipality, state of Mato Grosso (e.g., 9 o 41’10” S 59 o 35’19” W). Therefore, it is very imprecise to determine the exact point of type-locality with the current information.

Etymology. The species name, castaneus is a Latin word that means the color of chestnuts, related to the brownish body color of analyzed specimens and to the Brazil nut that named the type-locality (Igarapé do Castanhal).

Morphometry. The first Principal Component retained 96.3% of the original data variance (eigenvalue = 0.591616), all variable loadings were positive, which allows identification of this axis as the representative size. The morphometric discrimination of the new species concerning the comparative congeners occurred in the second axis, which retained 1.17% of the variance (eigenvalue = 0.00720634). Also, in this axis, it is observed that B. raninus syntype was closer to the group of B. raninus of Amazonia. In the third axis, which retained 0.60% of the variance (eigenvalue = 0.00367162), intraspecific variation was observed in B. transmontanus ( Fig. 15 ). From the analysis of individual scores distribution in PC1 and PC2, it was observed that the smaller individuals of B. transmontanus differ morphometrically from the larger individuals. In turn, the largest individuals tended to have similar morphometric characteristics to B. raninus .

The morphometric distinction of B. castaneus in relation to the other species analyzed was mainly due to the following characteristics: greater maxillary barbel length, larger eye diameter, greater dorsal-fin spine length, and larger mouth width (positive loadings on PC2). In turn, the new species had the smallest lengths of the adipose-fin base, anal-fin origin to the adipose-fin terminus and anal-fin base (negative loading on PC2). ( Table 2 ).

Figures

FIGURE 1. Holotype of Batrochoglanis castaneus, INPA 8059, 58,3 mm SL, Aripuanã River, Igarapé do Castanhal, MT.

FIGURE 2. Cranium of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. A) dorsal view; b) ventral view. Light blue = cartilage; dark gray = fontanel or foramen. Scale bar = 5 mm.

FIGURE 3. Autopalatine and maxilla of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. A) dorsal view; b) lateral view; c) ventral view; d) medial view. Light blue = cartilage. Scale bar = 1 mm.

FIGURE 4. Lower jaw of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. Light blue = cartilage. Scale bar = 1 mm.

FIGURE 5. Suspensorium of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. Light blue = cartilage; dark gray = foramen. Scale bar = 1 mm.

FIGURE 6. Hyoid arch of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype.A) lateral view; b) dorsal view of the anterior region. Light blue = cartilage. Scale bar = 5 mm.

FIGURE 7. Branchial arches of Batrochoglanis castaneus, a) dorsal view and b) ventral view of right epibranchials and pharyngobranchials, MZUEL 20113, 50.8 mm SL, paratype. Light blue = cartilage.

FIGURE 8. Ventral view of the left pectoral girdle of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. Light blue = cartilage. Scale bar = 5 mm.

FIGURE 9. Ventral view of right pelvic girdle of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. Light blue = cartilage. Scale bar = 1 mm.

FIGURE 10. Complex vertebra of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. A) Ventral view; b) ventral-lateral view of the anterior region. Scale bar = 1 mm.

FIGURE 11. Dorsal fin of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. A) dorsal view of nuchal plate and first two rays; b) lateral view. Light blue = cartilage. Scale bar = 1 mm.

FIGURE 12. Lateral view of anal-fin skeleton of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. Light blue = cartilage. Scale bar = 1 mm.

FIGURE 13. Caudal skeleton of Batrochoglanis castaneus, MZUEL 20113, 50.8 mm SL, paratype. Light blue = cartilage. Scale bar = 1 mm.

FIGURE 14. Laterosensory system of Batrochoglanis castaneus, INPA 8059, 58.3 mm SL, holotype. Scale bar = 5 mm. Open circle = laterosensory pore (i = infraorbital; ll = lateral line; pm = preoperculomandibular; po = postotic; s = supraorbital); dark dot = neuromast (al = anterior line; dtl = dorsal trunk line; ml = maxillary line; nl = nasal line; stal = supratemporal accessory line).

FIGURE 15. Scatterplot of individual scores of combined samples of Batrochoglanis castaneus (filled vine square, n=9), B. raninus from Amazon basin (green X, n=30), B. raninus syntype (red cross, n=1), B. transmontanus (open blue square, n=5) on the second and third axis of Principal Components.