Chaetostoma spondylus, Salcedo & Ortega, 2015

Salcedo, Norma J. & Ortega, Hernán, 2015, A new species of Chaetostoma, an armored catfish (Siluriformes: Loricariidae), from the río Marañón drainage, Amazon basin, Peru, Neotropical Ichthyology (Neotrop. Ichthyol.) 13 (1), pp. 151-156 : 152-155

Chaetostoma spondylus , new species

u r n:lsid:z o oba n k.org:a ct: C09CD0 02-D CB2- 41BE -872E - CE099C2B990A.

Fig. 1

Holotype. MUSM 33341, 119.7 mm SL, Peru, Departamento de Cajamarca, Celendín, Sorochuco, W of Sorochuco , río Sendamal , tributary of río Marañón , 6°51’29.5”S 78°15’35.2”W, 15 Oct 2008, D. Lopez.

Paratypes. All from Peru. Departamento de Cajamarca, Celendín, Sorochuco. MUSM 33338 , 3 , 45.9-115.1 mm SL, 1 c&s, 100.3 mm SL, río Churumayo , 6°52’15.5”S 78°15’23.8”W, 14 Oct 2008, D. Lopez. MUSM 33339 , 1, 101.5 mm SL, río Sendamal , 6°52’16.2”S 78°15’18.3”W, 14 Oct 2008, D. Lopez. MUSM 36146 , 2 , 44.2 and 91.2 mm SL, río Sendamal , 6°51’29.5”S 78°15’35.2”W, 22 Jun 2005, P. Golden. Departamento de Cajamarca, Chota , Querocoto. MUSM 40563 , 1, 117.6 mm SL, río Paltic , 6°20’20.2”S 79°05’40.4”W, 17 Jul 2007, R. Eakins. ROM 91081, 1, 121.7 mm SL, río Paltic , 6°20’20.2”S 79°05’40.4”W, 17 Jul 2007, R. Eakins. ROM 91082, 1, 101.5 mm SL, río Paltic , 6°20’08.8”S 79°22’18.5”W, 15 Jan 2008, R. Eakins. Departamento de Piura, Huancabamba, Huancabamba. MUSM 48327 , 2 , 56.1 and 65.9 mm SL, quebrada Chula, at mouth into río Huancabamba , 5°15’56.5”S 79°27’38.6”W, 3 Oct 2013, S. A. Schaefer, F. Provenzano & H. Ortega. MUSM 48328 , 2 , 51.1 and 85.8 mm SL, quebrada Chantaco, at bridge Sondor, 5°15’56.5”S 79°25’53.7”W, 3 Oct 2013, S. A. Schaefer, F. Provenzano & H. Ortega. Departamento de Amazonas, Chachapoyas, Leimebamba. MUSM 48330 , 1 , 72.3 mm SL, río Ollea , at San Francisco del Yeso , 6°13’46.4”S 77°43’55.6”W, 8 Oct 2013, S. A. Schaefer, F. Provenzano & H. Ortega .

Diagnosis. Chaetostoma spondylus is distinguished from all other Chaetostoma species by having a tuft of odontodes surrounded by naked skin, in the middle of each trunk lateral dermal plate, and more than 20 hypertrophied evertible odontodes on the three cheek plates vs. evenly distributed odontodes on the whole surface of each trunk lateral dermal plate and less than 20 hypertrophied evertible odontodes on the three cheek plates.

Description. Morphometric data in Table 1 . Head and body robust. Greatest body width at cleithrum and greater than head length, in specimens longer than 45 mm SL. Head and body depressed, greatest body depth greater than caudal-peduncle depth. Head profile straight to slightly convex from posterior border of naked snout to posterior border of nasal fossa, straight from posterior border of nasal fossa to posterior border of supraoccipital. Body profile slightly convex from posterior tip of supraoccipital to anterior dorsal-fin base, straight along dorsal-fin base to posterior border of pre-adipose plate, and slightly concave from posterior border of pre-adipose plate to anterior border of caudal fin. Ventral profile of head and body straight in most specimens; convex from posterior margin of cleithrum to pelvic-fin insertion in gravid females. Caudal peduncle trapezoidal in cross-section to anterior border of procurrent caudal-fin rays, triangular with apex dorsally from anterior border of procurrent caudal-fin rays to base of caudal fin. Caudal-peduncle width 88-110% of caudal-peduncle depth.

Body covered dorsally and laterally by plates. Plates with odontodes on most of surface dorsally from posterior border of head, including first mid-ventral plate, to anterior limit of dorsal fin, from posterior border of adipose fin to caudal-fin base, and ventrally from posterior free edge of anal-fin to caudal-fin base. Odontodes on dorsal, middorsal, median, and mid-ventral plate series restricted to middle portion of exposed plate. Plates from anterior limit of dorsal fin to caudal-fin base with tuft of odontodes in one to three rows, with one to five longer odontodes. Pectoralfin spine with enlarged dorsally and dorsolaterally oriented odontodes on dorsal surface. Body naked ventrally from tip of snout to ventral plates posterior to origin of anal fin. Caudal peduncle with coalescent plates ventrally along midline posterior to anal-fin base; first three plates mostly skin covered.

Dorsal fin with 8(3) or 9*(13) rays (one specimen with 6 dorsal rays, with apparently regenerating posteriormost dorsal rays), first ray unbranched. Dorsal-fin base plates 7*(5) or 8(11). Pre-adipose plate present* (9) or absent (3). Adipose fin conspicuous. Adipose spine ventrally compressed, blade-like, with dorsal margin transversely rounded. Depressed dorsal fin reaching pre-adipose plate. Plates between dorsal fin and adipose fin 4(3), 5(11), 6*(2). Plates between adipose fin and caudal fin 7(8), 8*(8). Anal fin reduced. Anal fin with 1*(1), 2(3), 3(13) rays; first ray unbranched. First anal-fin ray with none* (7) to 2(4) or more (1) rows of odontodes. Plates between anal fin and caudal fin 9(6), 10(8), 11*(2). Caudal fin truncated, with two unbranched and 14*(17) branched rays; dorsalmost and ventralmost rays unbranched.Posterior process of cleithrum partially exposed laterally; exposed part of cleithrum narrow, more or less triangular, obliquely oriented, with apex posterodorsally, and straight margins. Pectoral fin with one spine and six branched rays. Pectoral-fin spine strong and reaching to, or slightly beyond, pelvic-fin origin when adpressed. Pelvic fin with one unbranched and five branched rays. First unbranched pelvic-fin ray thick.

Anterior margin of snout rounded in dorsal view. Snout naked, densely covered with conspicuous blister-like, rounded papillae. Dense fat pads present beneath snout skin. Head with shallow ridge, extending from posterior border of naked snout lateral of nasal fossa to anterior border of eye. Head flat dorsally from posterior border of nasal fossa to posterior border of supraoccipital. Oral disk covered by blister-like rounded papillae, smaller than those on snout and not as closely positioned. Posterior lip margin with irregular lobes. Maxillary barbels short, conspicuous. Lateral half of posterior soft surface of each premaxilla with one to five rounded to digitiform papillae. Roof of oral cavity between premaxillae with fleshy digitiform buccal papilla. Anterior surface of dentary with four to ten rounded to digitiform papillae concentrated along twothirds of surface lateral from midline.

Premaxillary teeth in two rows with 47-64 in each row. Dentary teeth in two rows with 51-80 teeth in each row. Always more teeth in dentary than premaxilla. Teeth slender, asymmetrically bifid with tips blunt. Medial tooth cusp twice as long as lateral cusp. Lateral tooth cusp not juxtaposed over medial cusp on premaxillary teeth but slightly juxtaposed over almost full length of medial cusp on dentary teeth.

Hypertrophied evertible odontodes on three cheek plates embedded in soft connective tissue overlaying thick, fleshy flap anterior to opercular flap. Three cheek plates supporting 20 to 42 hypertrophied evertible odontodes. Hypertrophied evertible odontodes with distal tips straight to slightly curved anteriorly. Exposed part of opercle triangular, its free border with one or two rows of enlarged odontodes with distal tips straight to slightly curved posteriorly. Small opercular opening covered by fleshy opercular flap, bordered posteriorly by exposed cleithrum.

Infraorbital sensory canal extending beyond anterior border of first infraorbital canal-bearing plate. First infraorbital plate with laminar projections. Second infraorbital plate two to three times larger than first infraorbital. Third infraorbital plate situated along lateral rim of nasal fossa. Fourth through sixth infraorbital plates along anterolateral margin of orbit. Nasal plate long tube with no laminar projections. Frontal large and elongated, along posteromedial rim of nasal fossa and medial margin of orbit. Sphenotic rectangular, with wide lateral projection in contact with sixth infraorbital plate along posteromedial margin of orbit. Pterotic-supracleithrum not in contact with posterior margin of orbit. Suprapreopercle with wide lateral projections. Suprapreopercle in contact with sixth infraorbital plate.

Lateral line extending from posterior border of pteroticsupracleithrum to median plate at caudal-fin base or one immediately anterior. Lateral-line plates 23(1), 24(6), or 25*(10). First lateral-line plate in form of simple tube with narrow laminar expansions and embedded in skin. Second lateral-line plate one-half size of third median plate. Third lateral-line plate about same size as fourth plate.

Vertebrae 28*(5) or 29(1). Nine ribs (6). First rib thick and articulating directly to sixth centrum, second rib articulating to eighth centrum. Epural blade-like, separated from fused hypurals (hypurals 3-5 + uroneural), articulating dorsally to base of posteriormost procurrent rays and not reaching 27 th and 28 th centra ventrally (1).

Nuchal plate completely covered by bony plates and skin. First dorsal-fin spinelet completely covered by skin. Dorsal fin supported by nine pterygiophores (1), with first pterygiophore articulating with neural spine of seventh vertebra. Anal fin supported by 1*(3) or 2(2) pterygiophores (fused proximal and medial radials), with first pterygiophore contacting hemal spine of fifteenth vertebra.

Color in alcohol. Head and body brown dorsally. Body yellowish-brown ventrally. Irregular dark blotches present on body. Blotches ranging from rounded to narrow bands and noticeable on most specimens. Black spot present on base of membrane between first unbranched and first branched dorsal-fin rays. Dark brown first dorsal-fin ray followed by three to five (rarely six) dark bars on each dorsal-fin ray. Membranes with faint pigmentation mostly proximate to pigmented area on branched rays in specimens of SL> 50 mm. One to three dark bars on first dorsal-fin ray and on each branched dorsal-fin ray, membranes not pigmented in specimens of SL<50 mm. Caudal fin with four to six (rarely three or seven) dark bars on each ray. First bar on posterior margin of elongated plates at base of caudal fin. Anal fin with two or three dark bars; bars faint in some specimens. Pectoral-fin spine and rays coloration between six brown bars and overall brown with narrow light bars dorsally. Pectoral-fin membranes pigmented in most specimens. Pectoral fin light-brown ventrally. Pelvic-fin rays with four to six brown bars dorsally along their lengths, membranes pigmented along border of rays. Pelvic fin light-brown ventrally. Ventral plates of caudal peduncle brown.

Color in life. Body with greenish-brown ground color. Head with irregular dark blotches, about size of eye. Large dark blotches, twice size of eye, on plates between posterior border of head and anterior border of dorsal-fin origin. Body plates with large, irregular dark markings. Pectoral-fin and pelvic-fin membranes light red dorsally. Pectoral and pelvic fin-rays and membranes light red ventrally. Oral disk pinkish-brown. Body yellowish-white where naked. Plates ventrally dark brown on greenish-brown background.

Sexual dimorphism. None detected. All specimens have no fold to shallow fleshy fold along dorsomedial border of first pelvic-fin ray.

Distribution. Río Chotano, río Huancabamba, río Sendamal, and río Utcubamba, mountain tributaries (1500- 2000 m above sea level) of río Marañón, Amazon River basin, Peru ( Fig. 2 ).

Ecological notes. Based on the habitat description by Robert Eakins, who collected several specimens in the río Paltic. Species occurs in high gradient stream and rapids, over mostly boulder substrate. Waters highly oxygenated (8.2 mg /L) with almost neutral pH (7.1).

Etymology. The specific name, spondylus , is in reference to the tuft of odontodes on the trunk lateral dermal plates that resemble the thorny projections of the bivalve mollusk known as spiny oyster. A noun in apposition.

Figures

Fig. 1. Chaetostoma spondylus, new species, MUSM 33341, holotype, 119.7 mm SL, Peru, Departamento de Cajamarca, Celendín, Sorochuco, río Sendamal, tributary of río Marañón, Amazon basin.

Fig. 2. Geographic distribution of Chaetostoma spondylus. Symbols represent more than one lot, and more than one locality. Star indicates type locality.