Microglanis lundbergi, Jarduli & Shibatta, 2013

Jarduli, Lucas Ribeiro & Shibatta, Oscar Akio, 2013, Description of a new species of Microglanis (Siluriformes: Pseudopimelodidae) from the Amazon basin, Amazonas State, Brazil, Neotropical Ichthyology 11 (3), pp. 507-512 : 508-510

Microglanis lundbergi new species

Figs. 1-2

Holotype. INPA 28577 , 27.7 mm SL, Brazil, Amazonas , Tefé municipality, Alvarães, Costas das Capivaras, rio Solimões, 03º14.11’S 64º41.15’W, 13 Jan 2001, W. Crampton.

Paratypes. Brazil, Amazonas : INPA 18774 , 3 (1 c&s, 24.7 mm SL), 22.3-24.7 mm SL, collected with the holotype. MZUSP 112217 , 1 , 23.3 mm SL, between Santa Maria and Itacoatiara, rio Amazonas, close to rio Madeira (7.6 km upstream), stretch between 3º21’26.0”S 58º40’29.3”W and 3º21’24.1”S 58º39’36.2”W, 18 Oct 1994, Westneat et al. MZUSP 112218 , 1 , 23.1 mm SL, rio Amazonas , nearby tributary, rio Madeira (19.3 km downstream), Itacoatiara, stretch between 3º16’33.8”S 58º57’03.9”W and 3º16’46.7”S 58º56’34.0”W, 5 Aug 1996, A. Zanata et al. MZUSP 112219 , 2 , 21.2-25.7 mm SL, rio Amazonas , nearby tributary, rio Madeira (17.6 km downstream), Nova Oriente, stretch between 3º16’35.6”S 58º56’52.1”W and 3º16’49.1”S 58º56’36.5”W, 4 Aug 1996, Cox-Fernandes et al. MZUSP 112220 , 1 , 24.5 mm SL, rio Amazonas , nearby tributary, rio Madeira (22.2 km downstream), Nova Oriente, stretch between 3º16’40.8”S 58º56’52.8”W and 3º16’50.6”S 58º56’30.4”W, 4Aug 1996, C. Cox-Fernandes et al. MZUSP 112221 , 1 , 20.8 mm SL, rio Amazonas, nearby tributary, rio Madeira, stretch between 3º16’34.3”S 58º57’02.2”W and 3º16’45.2”S 58º56’39.8”W, 5 Aug 1996, M. Toledo-Piza et al .

Diagnosis. Microglanis lundbergi is distinguished from all congeners by the presence of a forked caudal fin with a deep notch between upper and lower lobes (vs. rounded, emarginated, or slightly forked), two pale juxtaposed and elliptical spots in the supraoccipital region (vs. wide, or narrow, or absent supraoccipital pale band), and shorter length of the adipose-fin base (13.1-16.6% of SL; except for M. carlae 14.7- 19.1%, M. secundus 12.2-18.2% and M. iheringi 14.7-19.0%). It also differs from other species on the following morphometric characters: length of the head 27.4-30.0% of SL (vs. 24.7-26.4% in M. carlae ; 23.9-25.1% in M. iheringi ; 23.0-26.1% in M. parahybae ; 23.0-25.4% in M. pataxo ; 23.5-26.3% in M. robustus ); eye diameter 8.0-9.9% of HL (v s. 12.4-17.6% in M. variegatus ); interorbital distance 40.4-44.2% of HL (vs. 45.9- 51.5% in M. cottoides ; 46.5-49.8% in M. leptostriatus ; 46.6- 48.6% in M. malabarbai ; 38.1-39.1% in M. pellopterygius ; 50.9-53.1% in M. poecilus ); mouth width 38.0-47.3% of HL (vs. 19.0-25.8% in M. cibelae ; 17.5-21.9% in M. garavelloi ; 20.1-22.6% in M. nigripinnis ); predorsal length 35.5-38.6% of SL (vs. 38.9-46.2% in M. eurystoma ); lateral line pores 6-8 (vs. 9 in M. ater and M. secundus ); principal caudal rays 15 (vs. 14 in M. zonatus ).

Description. Morphometric data are summarized in Table 1. Small size (up to 27.7 mm SL), head and anterior part of trunk depressed, laterally compressed from dorsal fin to caudal peduncle. Greatest body depth at dorsal-fin origin, greatest body width at pectoral-fin base.

Head slightly depressed, anteriorly rounded in dorsal view. Eye small, closer to mouth than to distal margin of operculum, more dorsal than lateral, inserted after first third of head length, completely covered by skin without free orbital margin. Snout short. Anterior nostril tubular, closer to upper lip than to eye; posterior nostril near anterior margin of eye, with anterior membrane. Gill membrane free from isthmus; nine branchiostegal rays. Gill rakers spiniform, usually small; first branchial arch with 1, 1, 4 gill rakers.

Mouth wide, terminal. Premaxillary tooth patch with rounded margin, no posterior projection. Dentary tooth patch semicircular, larger and wider than premaxillary patch. Tooth villiform, curved backwards.

All barbels thin, flattened in cross section. One maxillary pair, two mental pairs. Outer mental barbel surpassing pectoral-fin spine base; inner mental barbel shorter, reaching almost half length of outer mental barbel. Maxillary barbel short, not reaching pectoral-fin base. Dorsal fin I,6, located anteriorly to half of body length, posterior margin rounded; spinelet present. Dorsal-fin spine straight, shorter than branched rays.

Adipose fin relatively small. Caudal fin forked with deep notch, lower lobe slightly longer than upper lobe. Principal caudal rays 15, dorsal procurrent rays 15, ventral procurrent rays 10. Anal fin short and rounded, iv,7. Pectoral fin I,5. Pectoral spine strong, slightly flattened, with developed serrations on both margins, completely covered by thin skin. Anterior margin of pectoral spine with 10-14 hooks; hooks on distal portion antrorse or straight. Posterior margin of pectoral spine with 7-9 retrorse serrations greater than anterior margin, increasing in size from proximal to distal portion ( Fig. 2 ). Tip of pectoral spine ossified, very strong and sharp. Pelvic fin rounded, with i,5 rays. Vertebrae 27. Ribs 6.

Posterior cleithral process short, narrow and pointed, spiniform. Proximal pterygiophores 9. Swim bladder relatively large, filling almost entire abdominal cavity (length 21.5% of SL, width 13.0% of SL), cordiform, with simple T-shaped septum. Trunk lateral line with 6-8 pores, not surpassing vertical through end of dorsal-fin base.

Color in alcohol. Ground color orange-brown. Head dark-brown with two elliptical and juxtaposed pale spots in supraoccipital region, confluent or not with a pale band in post-opercular region, reaching pectoral-fin base. Two small, semilunar, pale stripes in anterior region of head in dorsal view, between edge of snout and anterior orbital margin. Barbels pale, scattered by dark-brown chromatophores.

Ventral region light-brown. Trunk with large dark-brown blotch, saddle shaped, horizontally divided by pale lateral line. Caudal region with two dark-brown blotches of irregular shape. First one at dorsolateral position, beginning below anterior portion of adipose fin, extending up to half of caudal length. Second one at caudal peduncle, as dark brown spot approximately rectangular with irregular margins.

Pectoral and pelvic fins with scattered dark chromatophores. Dorsal fin with dark band covering distal half, with hyaline margin on all rays. Adipose fin with dark spot on anterior portion, confluent to caudal dark-brown blotch. Anal fin with thin dark band approximately median. Caudal fin with thin vertical “3-shaped”dark band.

Distribution. Microglanis lundbergi is known from rio Amazonas, near the Madeira and Itacoatiara tributaries, and from rio Solimões, in Tefé, Amazonas, Brazil ( Fig. 3 ).

Habitat notes. Theindividualswerecollectedinthemainchannel of the rioAmazonas (white waters), bottom rich in organic matter and pieces of wood (data obtained from lots’ labels).

Etymology. The specific name is homage to the North American ichthyologist John G. Lundberg, coordinator of the Calhamazon project, who kindly provided specimens of the new species, and for his great contribution to the Systematics of Neotropical catfishes.

Figures

Fig. 1. Dorsal (a), lateral (b) and ventral (c) view of Microglanis lundbergi, INPA 28577, holotype, 27.7 mm SL, rio Solimões, Tefé, Costa das Capivaras,Amazonas, Brazil.

Fig. 2. Dorsal view of left pectoral spine of Microglanis lundbergi INPA 28577, 27.7 mm SL, holotype, rio Solimões, Tefé,Costa das Capivaras,Amazonas, Brazil.Scale bar = 1 mm.

Fig. 3. Map of distribution (black dots) of Microglanis lundbergi. Red star = type locality. Brazilian states acronym: AC=Acre;AM =Amazonas;AP =Amapá;MT = MatoGrosso; PA = Pará; RR = Roraima.