Spectracanthicus immaculatus, Chamon & Rapp Py-Daniel, 2014

Chamon, Carine C. & Rapp Py-Daniel, Lúcia H., 2014, Taxonomic revision of Spectracanthicus Nijssen & Isbrücker (Loricariidae: Hypostominae: Ancistrini), with description of three new species, Neotropical Ichthyology 12 (1), pp. 1-25 : 12-16

Spectracanthicus immaculatus , new species Figs. 9-10

Holotype. MZUSP 92797 , 63.8 mm SL, Brazil, Pará, rio Tapajós, near Itaituba , approximately 4°16’46.56”S 55°59’5.77”W, 7 Nov 2006, L. M. Sousa & J. L. Birindelli.

Paratypes. MZUSP 92617 , 11 , 38.2-82.2 mm SL (1 c&s, 81.2 mm SL), Brazil, Pará, rio Tapajós near Itaituba and Pimental , approximately 4°16’46.56”S 55°59’5.77”W, 8 Nov 2006, L.M. Sousa & J. L. Birindelli .

Diagnosis. Spectracanthicus immaculatus can be distinguished from all congeners by its color pattern consisting of a dark gray body, without dots or spots, and by having very slender teeth (vs. with small to mid-sized yellowish dots in S. punctatissimus , S. murinus , and S. tocantinensis ; and large white spots in S. zuanoni ). It further differs from Spectracanthicus punctatissimus and S. zuanoni by the pointed snout in dorsal view (vs. snout rounded). Other characters that differs the new species from other congeners are: nasal quadrangular (vs. nasal L-shaped); posterior margin of pterotic-supracleithrum without contact with posterior margin of orbit (vs. with large contact with orbit in S. murinus and small contact in remaining species); cartilage area of basipterygia short (vs. elongate in remaining species, except in S. murinus ); anterior fenestrae of cartilage area of basipterygia large in size (vs. small to median size in remaining species, except in S. tocantinensis ) ( Fig. 11 ).

Description. Morphometric and meristic data summarized in Table 3 . Dorsal profile of body slightly convex from tip of snout to vertical through of dorsal fin; concave, nearly straight from that point to caudal-fin origin.Ventral profile straight from snout tip to origin of caudal fin.Ventral surface from tip of snout to urogenital papillae lacking plates, except for few small plates at pectoral and pelvic-fins origins. Body deep and robust even at caudal peduncle. Head and trunk lacking keels or ridges. Greatest body depth at dorsal-fin origin; lowest at caudal peduncle.

Head wide, convex dorsally; snout and cheeks completely covered by numerous small plates, except for small naked area on tip of snout. Snout slightly rounded in dorsal profile. Nasal elongated, L-shaped. Frontal short with a slight contact with nares anteriorly and orbit posteriorly. Anterior margin of frontal short, reaching posterior margin or half of length of nare. Parieto-supraoccipital short with posterior edge narrow, lacking crest. Sphenotic short, without contact with IO6, lacking conspicuous odontodes. Orbit moderate in size (13.6-16.2% HL), placed dorsolaterally in head. Iris with small dorsal flap over pupil. Pterotic-supracleithrum short with few fenestrae; anterior process forming most posterior margin of orbit. Posterior area of pterotic-supracleithrum with one plate.

Mouth moderate in size, nearly as long as wide. Lips large, covered with papillae; size of papillae decreasing towards posterior margin of lower lip; central buccal papilla absent. Upper lip folded over itself. Maxillary barbel short; base of barbel united to lips with free tip. Lower lip not reaching anterior margin of coracoid. Medial end of premaxillary teeth series almost straight. Premaxillae and dentaries narrow and elongate. Dentaries strongly curved inwards. Teeth medium in size, well developed, slender, with long crown and large lateral cusp. Distal edge of teeth slightly curved inward. Eversible cheek plates with associated hypertrophied odontodes and disposed as unique block connected to opercle, that can be everted to approximately 90 o from head by opercle movements ( Fig. 12 ).

Body covered by five longitudinal series of plates supporting odontodes. Keels absent. Three to four predorsal plates; some small azygous predorsal plates sometimes present. Eight neural bifid spines supporting dorsal fin. Dorsal-fin rays i,7, located posterior to neural spines of vertebral centra 7-17. Dorsal-fin base very long, its length equivalent to 12 dorsal plates, reaching pre-adipose plate and connected to adipose fin by thick membrane. Dorsal-fin spinelet V-shaped with locking mechanism. Pectoral and pelvic fins well developed, medial portion much expanded relative to base; distal margins rounded. Pectoral-fin rays I,6; unbranched ray covered with conspicuous odontodes. Tip of adpressed pectoral fin almost reaching vertical through medial, unbranched, pelvic-fin ray. Pelvic-fin rays i,5; pelvic-fin spine reaching vertical through anal-fin base when adpressed. Anal-fin rays i,4 located posterior to hemal spines of vertebral centra 14-17. Caudal-fin rays i,14,i, truncated; supracaudal plates. Five to six procurrent caudal-fin rays. Caudal peduncle strongly deep in lateral view. Total vertebrae 26, precaudal 8-12. Sixth rib strongly thickened, remaining ribs slender. Infraorbital with 7-8 pores. Infraorbital 4 with little contact with orbit by posterior margin. Infraorbital 6 forming only postero-vental part of orbit. Lateral line pores restrict to hypural plate.

Color in alchool. Ground color evenly dark gray to dark brown without dots or spots. Ventral surface ochre to light brown without dots. Dorsal surface of body of live specimens gray.

Distribution. Spectracanthicus immaculatus is known from rio Tapajós basin, near Itaituba and Pimental, Pará State, Brazil.

Etymology. The specific epithet “ immaculatus ” derives from Latin, meaning unspotted or unstained, in allusion to the coloration pattern of the species, lacking dots or spots. An adjective.

Fishery and economical importance. Spectracanthicus immaculatus is an important resource of ornamental fish. It is also recognized by local fishermen and aquarists as “naná” or “L363” (L-number; Schraml & Schafer, 2004; Werner et al. 2005). Like S. murinus , it is also captured by diving with help of a compressor, a typical way of capturing ornamental fishes in Itaituba and Santarém regions (Sousa & Birindelli, 2009).

Figures

Fig. 9. Spectracanthicus immaculatus, holotype, MZUSP 92797, 64.6 mm SL, rio Tapajós, Pará State, Brazil.

Fig. 10. Color in live of Spectracanthicus immaculatus, paratype, MZUSP 92617, 81.2 mm SL. Image by L. Sousa.

Fig. 11. Basipterygia and pelvic fin of (a) Spectracanthicus murinus, MZUSP 24293, 37.0 mm SL; (b) S. immaculatus, paratype, MZUSP 92617; 58.9 mm SL and (c)S. tocantinensis, paratype, MZUSP 34265,65.4 mm SL.Scale bars = 2 mm. Imageby E. Baena.

Fig. 12. Suspensorium of Spectracanthicus immaculatus, (a) external view and (b) internal view, paratype, MZUSP 92617, 58.9 mm SL. Scale bars = 2 mm. Image by E. Baena.