Spectracanthicus murinus Nijssen & Isbrücker, 1987

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 : 2-5

Spectracanthicus murinus Nijssen & Isbrücker, 1987 Figs. 1-2

Spectracanthicus murinus Nijssen & Isbrücker, 1987: 94 , fig. 1 [type locality: Poça de Pedra, rio Tapajós, Pará, Brazil]. - Burgess, 1989: 445 [citation]. - Eschmeyer, 1998: 1138 [catalog]. - Isbrücker, 2001: 32 [catalog]. - Isbrücker, 2002: 29 [catalog]. - Fisch-Müller, 2003: 395 [catalog]. - Ferraris, 2007: 297 [catalog]. - Lujan et al., 2009: 50-56 [citation]. - Camargo et al., 2012:169 [catalog, picture].

Diagnosis. Spectracanthicus murinus is distinguished from its congeners by the non-eversible cheek plate (vs. check plate eversible); the triangular-shaped opercle (vs. bar shaped); presence of three branched anal-fin rays (vs. four); pale (yellow in life) bars on tip of dorsal and caudal fins (vs. bars absent; except in some specimens of S. punctatissimus ); the frontal forming a small portion of orbit border (less than ¼ vs. frontal forming a large portion of orbit border); the anterior process of the pterotic-supracleithrum forming the posterior margin of orbit (vs. pterotic-supracleithrum not forming posterior margin of orbit in S. immaculatus or contacting only a small area of orbit posterior margin in remaining species). Spectracanthicus murinus can be further distinguished from S. immaculatus n. sp. and S. zuanoni n. sp. by having pale (yellow in life) small dots on body and fins (vs. dots or spots absent, body and fins dark gray in S. immaculatus ; or with large white spots in S. zuanoni ). It can be also distinguished from S. punctatissimus and S. tocantinensis n. sp. by the lower counts of premaxillary and dentary teeth, 2 to 3 and 5 respectively (vs. 3 to 25 and 8 to 46 in S. punctatissimus ; and 5 to 8 and 8-16 in S. tocantinensis ).

Description. Morphometric and meristic data are summarized in Table 1 . Dorsal profile of body slightly convex from tip of snout to vertical through dorsal-fin origin; concave, nearly straight from that point to caudal-fin origin.Ventral profile of body straight from snout tip to caudal-fin origin. Ventral surface from tip of snout to urogenital papillae lacking plates, except for few small plates at pectoral- and pelvic-fin origins. Greatest body width at pectoral girdle. Head and trunk lacking keels or ridges. Greatest body depth at dorsal-fin origin; lowest at caudal peduncle.

Head wide, pointed anteriorlly; snout and cheek completely covered by numerous small plates, except for small naked area on tip of snout. Snout slightly pointed in dorsal view. Nasal L-shaped, elongate. Frontal short with a slight contact with nares anteriorly and orbit posteriorly Anterior margin of frontal short, reaching posterior margin, or half length, of nare. Parieto-supraoccipital short with posterior edge narrow, lacking crest. Sphenotic short, contacting IO6; lacking conspicuous odontodes. Orbit moderate in size (14.1-33.4% HL) placed dorsolaterally. Iris with small dorsal flap over pupil. Pteroticsupracleithrum short with few fenestrae; anterior process forming most posterior margin of orbit. Posterior area of pterotic-supracleithrum with one median sized 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 curved inwards. Premaxillae ( Fig. 3 ) and dentary narrow and elongate. Dentary strongly curved inwards. Teeth slightly thick, well developed, with long crown and large lateral cusp; its distal edge slightly curved inward. Three to four pairs of well developed predorsal plates. Cheek plates not eversible; without associated hypertrophied odontodes ( Fig. 4 ).

Body covered by five longitudinal series of plates supporting odontodes. Keels absent. Three to four predorsal plates; small azygous predorsal plates sometimes present between predorsal plates. Eight furcate neural spines supporting dorsal fin.

Dorsal-fin rays i,7, pterygiophores 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; connected to adipose fin by thick membrane. Dorsal-fin spinelet V-shaped with lock mechanism. Pectoral and pelvic fins well developed, medial portion much expanded relative to base; distal margin 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,3, located posterior to haemal spines of vertebral centra 14- 17. Caudal fin i,14,i, truncate; supracaudal plates 7. Usually four procurrent caudal-fin rays. Caudal peduncle strongly deep. 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 posterior margin. Infraorbital 6 forming only postero-vental part of orbit. Lateral line pores restricted to hypural plate.

Color in alcohol. Dorsal surface of body dark brown with numerous small, yellow dots regularly distributed along head, body and fins. Most specimens with pale, bar-shaped patch lacking chromatophores on caudal-fin distal tip. Ventral surface ochre without dots. Long time preserved specimens

may present faint dots along body and fins.

Geographic distribution. Spectracanthicus murinus is known from the rio Tapajós basin, near Itaituba and Santarém, Pará State, Brazil ( Fig. 5 ).

Fisheries and economical importance. Spectracanthicus murinus is an important resource of ornamental fish. It is recognized by local fishermen and aquarists as “bicudo” (snouty). It is usually captured by diving with the aid of a compressor, a typical way to capture ornamental fishes in Itaituba and Santarém regions (Sousa & Birindelli, 2009). The species citation to rio Xingu basin in Camargo et al., 2012 is probably a misidentification (H. Gimenes Junior, pers. comm.). Material examined. Holotype. MZUSP 22011 , 59.7 , Brazil, Pará, São 1, 62.6 mm SL, Trairão , rio Jamaxim , ilha Terra Preta , 5°27’11”S Luis, rio Tapajós , 4°27’0.02”S 56°15’0.00”W, Expedição Permanente 55°52’40”W, 20 Oct 1991, L. Rapp Py-Daniel & J. Zuanon. INPA à Amazônia, H. A. Britski et al. Paratypes. All from Brazil, Pará, 26480, 1, 62.55 mm SL, Itaituba , obtained from ornamental fish rio Tapajós : MZUSP 21849 , 2 , 44.2-58.2 mm SL, São Luís , rio fishermen, 08 Nov 2006, L. M. Sousa & J. L. Birindelli. INPA 26483 , Tapajós , Cachoeira Lombo de Anta , 4°27’60.00”S 56°14’60.00”W, 6, 44.4-84.8 mm SL, Itaituba , donate by fishmen of ornamental fish, Sep 1970, Expedição Permanente à Amazônia. MZUSP 27633 , 1 , 08 Nov 2006, L. M. Sousa & J. L. Birindelli. INPA 26488 , 8 , 60.4 - 96.7 45.0 mm SL, São Luis , rio Tapajós , cachoeira do Maranhãozinho , mm SL, Itaituba , above Itaituba and below cachoeiras de Pimental, 4°28’0.00”S 56°15’0.00”W, Expedição Permanente à Amazônia. 4°21’34”S 056°10’02”W, 08 Nov 2006, L. M. Sousa & J. L. Birindelli. ZMA 107.878 , 2 , 55.5-63.6 mm SL, São Luís , rio Tapajós , Cachoeira INPA 26507 , 2 , 4.7-57.6 mm SL, Pimental , corredeira do Pajaú e Lombo de Anta , 4°27’60”S 56°14’60”W, 6 Oct 1970, Expedição arredores, 4°35’04”S 56°15’32”W, 11 Nov 2006, L. M. Sousa & J. Permanente à Amazônia. ZMA 107.877 , 1 , 58.6 mm SL, São Luís, L. Birindelli. MZUSP 24293 , 2 , 36.1-39.1 mm SL (1 c&s, 36.1 mm poça de pedra no rio Tapajós , 8 Oct 1970. ZMA 107.876 , 1 , 44.1 SL) São Luís , cachoeira do Maranhãozinho , 4°28’S 56°15’W, 06-07 mm SL, Cachoeira do Maranhãozinho , rio Tapajós , near São Luis , Nov 1970, Expedição Permanente à Amazônia. MZUSP 34279 , 13 , 4°28’00”S 56°15’00”W, 06-07 Oct 1970, Expedição Permanente 19.0- 46.2 mm SL (1 c&s, 36.8 mm SL) Pederneiras , below Itaituba , à Amazônia. Non-type. Brazil, Pará, rio Tapajós : INPA 6990 , 4°16’41”S 55°59’09”W, 24 Out 1983, M. Goulding.

Figures

Fig. 1. Spectracanthicus murinus, holotype, MZUSP 22011, 59.7 mm SL, rio Tapajós, Pará State, Brazil.

Fig. 2. Color in life of Spectracanthicus murinus (Image by L. M. Sousa).

Fig. 3. Palatine, maxillar, and premaxillar in (a) Spectracanthicus murinus, MZUSP 24293, 37.0 mm SL, (b) Spectracanthicus zuanoni, INPA 3957, 57.0 mm SL, (c) Spectracanthicus immaculatus, paratype, MZUSP 92617, 58.9 mm SL and (d) Spectracanthicus tocantinensis, paratype, MZUSP 34265, 65.4 mm SL.

Fig. 4. Suspensorium of Spectracanthicus murinus, MZUSP 24293, 37.0 mm SL. a. internal view; b. external view. 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.