Spectracanthicus tocantinensis, 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 : 17-18

Spectracanthicus tocantinensis , new species Fig. 13

Holotype. MZUSP 110989 , 49.5 mm SL; Brazil, Pará, Carreira Comprida, rio Itacaiunas , Tocantins drainage, 5°22’S 49° 07’W, M. Goulding, 14 Oct 1983.

Paratypes. All from Brazil, Pará, rio Tocantins drainage. INPA 6045 , 7 , 43.13-76.9 mm SL, poço d’água downstream of Tucuruí Dam, rio Tocantins , 09 Oct 1984, Ichthyology staff, INPA (G. M. Santos & B. Mérona). INPA 6049 , 1 , 61.8 mm SL, rio Tocantins , Jatobal , Tucuruí , 05 Jul 1982, Ichthyology staff, INPA. INPA 6050 , 1 , 62.8 mm SL, rio Tocantins , Jatobal , Tucuruí , 17 Jul 2008, Ichthyology staff, INPA. INPA 2990 , 140 , 16.2-92.9 mm SL, rio Tocantins , downstream of Tucuruí Dam , 3°45’58”S 49°40’21”W, 31 Ago 1984, Ichthyology staff, INPA. INPA 11133 , 2 , 78.3-86.2 mm SL, rio Tocantins , Tucuruí, 01 Sep 1981, Ichthyology staff, INPA. FMNH 95555 , 1 , 64.0 mm SL, lagoon in front of Jatobal, rio Tocantins , 4°34’00”S 49°39’00”W, 16 Sep 1970, Expedição Permanente à Amazônia. MNRJ 19347 , 175 , 36.0- 85.3 mm SL; rio Tocantins , near Tucuruí, Sep 1984, L. C. Alvarenga. MNRJ 19359 , 29 , 60.8-82.7 mm SL, rio Tocantins , near Tucuruí, Sep 1984, L. C. Alvarenga. MNRJ 19373 , 7 , 60.0-63.0 mm SL, rio Tocantins , near Tucurui, Sep 1984, L. C. Alvarenga. MZUSP 24125 , 7 , 56.4 -74.0 mm SL (1 c&s, 64.2 mm SL), Jatobal, lagoon in front of Jatobal, rio Tocantins , 49°39’00”W 4°34’00”S, 16 Sep 1970, Expedição permanente à Amazônia. MZUSP 34265 , 11 , 38.7 -72.0 mm SL (1 c&s, 65.4 mm SL), same locality as holotype. MZUSP 39927 , 1 , 64.5 mm SL, lagoon in front of Jatobal, rio Tocantins , 4°34’00”S 49°39’00”W, 16 Sep 1970, Expedição Permanente à Amazônia .

Diagnosis. Spectracanthicus tocantinensis can be diagnosed from its congeners by the infraorbital 4 forming most of the posterior edge of the orbit (vs. IO4 forming a minute portion of orbital rim) and by the large basipterigium fenestrae (vs. medium or small-sized basipterigium fenestrae) ( Fig.11 ). It can be further distinguished from S. immaculatus and S. zuanoni by its color pattern, consisting of small, yellowish dots, and by the presence of thick teeth (vs. dots lacking in S. immaculatus and large, white spots in S. zuanoni ; and slender teeth). It is additionally distinguished from S. zuanoni by the lower number of dentary teeth (8-16 vs.19-43). Spectracanthicus tocantinensis differs from S. murinus by the presence of a bar-shaped, eversible opercle with conspicuous odontodes (vs. triangle shaped opercle not eversible, without conspicuous odontodes) and by the presence of four unbranched anal-fin rays (vs. three unbranched anal-fin rays). The new species further differs from S. punctatissimus by the slightly pointed snout in dorsal view (vs. snout rounded in dorsal view).

Description. Morphometric and meristic data are summarized in Table 4 . 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-fin 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 (15.4-20.3% 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 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 6-17. 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 its 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. Caudalfin rays i,14,i, truncated; seven supracaudal plates. Five to six procurrent caudal-fin rays. Caudal peduncle strongly deep in lateral view. Total vertebrae 26, precaudal 8-12. Ribs slender, except strong sixth rib. Infraorbital with 7-8 pores. Infraorbital 4 with great contact with orbit by posterior margin. Infraorbital 6 formed just postero-vental part of orbit. Lateral line pores restrict to hypural plate.

Color in alcohol. Dorsal surface of body and fins dark brown with small to median-sized yellowish dots regularly distributed along head, trunk and fins. Body dots sparced and usually fewer in juveniles. Ventral surface light tan without dots.

Geographic distribution. Spectracanthicus tocantinensis is known from the lower rio Tocantins, near Tucuruí and Jatobal, Pará, Brazil ( Fig. 5 ) .

Etymology. The specific epithet “ tocantinensis ” is in allusion to the type locality of the new species, the rio Tocantins. An adjective.

Figures

Fig.13. Spectracanthicus tocantinensis,holotype,MZUSP 110989, 56.4mm SL, rioTocantins,Pará State,Brazil.Image byE.Baena.

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.

Fig. 5. Distribution map for the species of Spectracanthicus. Circles, S. murinus; stars, S. punctatissimus; squares, S. immaculatus; triangle, S. tocantinensis and diamon, S. zuanoni. White symbols refers to type locality.