Notarius armbrusteri, Ricardo Betancur-R. & Arturo Acero P., 2006

Ricardo Betancur-R. & Arturo Acero P., 2006, A new species of Notarius (Siluriformes: Ariidae) from the Colombian Pacific., Zootaxa 1249, pp. 47-59 : 50-56

Notarius armbrusteri new species

Figs. 2-3

Arius planiceps non Steindachner: Acero P. and Betancur-R. (2002): 9, Fig. 3.

Holotype. INVEMAR-PEC 6677 (undeposited tissue tagged as 527), female, 194 mm SL, purchased by R. Betancur-R. and A. Acero P., 28 May 2004, fish market of Buenaventura, Valle del Cauca (VC), Colombia (CO); cyt b, ATPase 8 and ATPase 6 sequences are available in GenBank, accession numbers DQ373045, DQ373041, and DQ373043, respectively.

Paratypes. INVEMAR-PEC 6678 (undeposited tissue tagged as 529), male, 177 mm SL, same collection data as holotype; cyt b, ATPase 8 and ATPase 6 sequences are available in GenBank, accession numbers DQ373046, DQ373042, and DQ373044, respectively. ICN-MHN 14829, female, 208 mm SL, unsexed specimen, same collection data as holotype. USNM 292738, female, 205 mm SL, purchased by W.R. Taylor, 17 October 1970, fish market of Buenaventura, VC, CO. USNM 264834, skeletonized specimen, 69 mm skull length, purchased at fish market of Buenaventura, VC, CO, catalogued 25 January 1984.

Diagnosis. Notarius armbrusteri is distinguished from other EP species of Notarius by the following combination of features: mouth rather small, its width 11.1-11.8% SL; eye large, diameter 4.3-4.9% SL; distance between anterior nostrils 6.1-6.9% SL, distance between posterior nostrils 5.9-6.9% SL; short maxillary barbels, barely reaching pectoralfin bases, their length 20.5-22.2% SL; and gill rakers on first arch 3-4+8-9 (total 11-13). Meristic and morphometric data of the type series are summarized in Tables 2 and 3, respectively. Selected features distinguishing N. armbrusteri from the seven other EP species of Notarius are summarized in Table 4. See key section at the end for diagnostic characters distinguishing the new species from other EP ariid taxa.

Description (based on combined data from type series). Body depth 5.0-5.4 in SL; body width 4.7-5.2 in SL. Head not elongated, moderately depressed anteriorly, posterior profile slightly convex, length 3.7-4.1 in SL, width 1.1-1.2 in HL, depth 1.5-1.7 in HL. Snout rounded, length 3.1-3.4 in HL. Mouth inferior to subterminal, width 2.1-2.4 in HL. Lips thin to moderately thick, upper lip width 9.8-18.5 in HL. Maxillary barbels 1.2-1.3 in HL; mandibulary barbels 1.6-1.8 in HL, passing gill membrane; mental barbels 2.2-2.4 in HL, not reaching gill membrane. Distance between anterior nostrils 3.9-4.0 in HL; distance between posterior nostrils 3.9-4.2 in HL, no fleshy furrow connecting nostrils. Interorbital distance 1.9-2.2 in HL. Eyes lateral, diameter 5.1-6.2 in HL, 2.6-3.0 in interorbital distance. Postorbital length 1.8-2.0 in HL. Head shield exposed, covered posteriorly with dense layer of tiny granules extending anteriorly to opposite eyes (granules sometimes not very apparent). Frontal depression broad, with large pale spot on anterior margin immediately after interorbital space. Supraoccipital process keeled, rather short, slightly convex; length 3.6-4.7 in HL; width 3.6-4.0 in HL, 0.8-1.0 in length. E pioccipital bones (= epiotics) not invading or slightly invading skull surface (Fig. 1B). Predorsal plate narrow, crescent-shaped. Premaxillary teeth villiform, arranged in two subrectangular bands forming wide arrow point (Fig. 4). Palate with villiform teeth, arranged in four patches: inner patches (vomerine) united medially, longer than wide; lateral patches broader, triangular, projected posteriorly, with an indentation into which fit inner patches (Fig. 4).

Predorsal fin length 2.6-3.1 in SL. Dorsal-fin base 8.3-9.0 in SL; dorsal-fin spine long, rather thin, longer than pectoral-fin spine, with small serrations along external margin, inner margin slightly serrated only in distal end; height 4.4-4.7 in SL. Distance between dorsal fin and adipose fin 3.5-3.9 in SL. Base of adipose fin 8.0-8.6 in SL, as long as or somewhat longer than base of dorsal fin, 0.9-1.0 in dorsal-fin base; height of adipose fin 9.1-10.2 in SL. Pectoral-fin base 15.5-16.7 in SL; pectoral-fin spine long, thin, slightly serrated along external margin, serrations on inner margin smaller and absent near proximal end; length 4.6-5.0 in SL. Pelvic-fin base 20.0-21.3 in SL; pelvic-fin length 5.3-5.7 in SL in females and 7.1 in SL in one male. Anal-fin base 6.0-6.5 in SL; anal-fin height 5.2-5.7 in SL. Caudal peduncle depth 13.5-14.3 in SL. Caudal fin deeply forked, lower lobe shorter than upper lobe. Lateral line originating below predorsal plate, tilting ventrally to mid-body line at about level of pelvic-fin origin, running posteriorly, bending dorsally before caudal fin. Gill rakers on second arch 3-4+9 (total 12-13). Dorsal fin elements I,7; pectoral fin elements I,11-12; pelvic fin elements 6; anal fin elements 19-22.

Coloration. In life, dorsum brownish grey with metallic tinges, flanks and venter whitish. Lower caudal fin lobe and tip of anal fin dark; pectoral and pelvic fins dark, distal tips pale. In alcohol, coloration fades, metallic tinges disappear.

Size. Largest female specimen examined 208 mm SL (ICN-MHN 14829, paratype), largest male 177 mm SL (INVEMAR-PEC 6678, paratype). Female ariids have a greater development of pelvic fins than have males, and this dimorphism exhibits a positive allometry becoming more evident in mature specimens (Acero P. et al., 2005). Given that there is a clear difference in the size of pelvics between female (17.5-18.5% SL) and male (14.1% SL) specimens, it seems likely that Notarius armbrusteri reaches maturity below 200 mm SL and is probably the smallest known species of Notarius .

Distribution and habitat. Notarius armbrusteri is known only from Buenaventura, Valle del Cauca, Colombian Pacific. The species has not been recorded from Tumaco, Nariño, CO, about 300 km southwestwards from Buenaventura (pers. obs.). Habitat preferences are unknown.

Etymology. Named for Dr. Jonathan W. Armbruster, curator of the Auburn University Museum, in recognition of his important contributions to the taxonomy of neotropical catfishes. We suggest the common names of “ Ñato Sea Catfish”, “bagre ñato ” (Spanish, name given by fishermen in the area), and “ mâchoiron ñato ” (French).

Discussion

A new molecular phylogeny for the species of Notarius , inferred from the combined cyt b + ATPase 8/6 dataset, is presented in Fig. 5. The mitochondrial evidence suggests that N. armbrusteri is the sister species of N. insculptus , from the Pacific coast of Panama; the bootstrap supporting this clade is strong (100%). The combined mitochondrial K2P distances between haplotypes of N. armbrusteri and N. insculptus are 4.1-4.2%. Both species are also related to the N. planiceps /aff. planiceps group (bootstrap 94%), known from the Pacific Panama to Mexico. Despite the few specimens in the type series (five complete and one skeletonized), the fact that N. armbrusteri is well discriminated as a separate and monophyletic entity among EP species of Notarius in the phylogram, gives strong support for its specific status.

Notarius armbrusteri can be separated from its sister species, N. insculptus , by the following features: epioccipitals not invading or only slightly invading skull surface (Fig. 1B) (vs. widely invading in N. insculptus , Fig. 1A), complex process (formed by the epioccipitals and the supraoccipital) absent (Fig. 1B) (vs. present in N. insculptus , Fig. 1A); two pairs of palatal tooth patches present (vs. three pairs in N. insculptus ); smaller mouth (11.1-11.8% SL in N. armbrusteri vs. 12.3-14.4% SL in N. insculptus ); shorter maxillary barbels (20.5-22.2% SL in N. armbrusteri vs. 26.7-30.3% SL in N. insculptus ); and larger eyes (4.3-4.9% SL in N. armbrusteri vs. 3.8-4.3% SL in N. insculptus ). Other EP species of Notarius are compared in Table 4.