Tatia dunni (Fowler, 1945)

Sarmento-Soares, Luisa Maria & Martins-Pinheiro, Ronaldo Fernando, 2008, A systematic revision of Tatia (Siluriformes: Auchenipteridae: Centromochlinae), Neotropical Ichthyology 6 (3), pp. 495-542 : 513-514

Tatia dunni (Fowler, 1945)

Figs. 19-21

Centromochlus intermedius . Steindachner, 1882: 4 [Jutaí and Jatuarana]. Eigenmann & Eigenmann, 1888: 156 [Tajapuru, Tefé, Jatuarana, Icá, Jutaí, LagoAleixo]. Eigenmann & Eigenmann, 1890: 269 [Amazonas, Solimões and tributaries].

Centromochlus aulopygius . Eigenmann & Eigenmann, 1891: 34 [in part, Amazonas, Solimões and tributaries]. Miranda Ribeiro, 1968:10, fig. IX [Amazonas].

Tatia intermedia . Miranda Ribeiro, 1911: 360 [in part, Jutaí, Jutuarana, Tajapuru, Teffé, Içá, LagoAleixo]. Gosline, 1945: 10 [Amazonas, Solimões and Tributaries]. Sands, 1984: 37 [reference].Ortega& Vari, 1986:14 [reference]. Burgess, 1989: 242, pl. 113 [Amazon]. Soares-Porto, 1998: 333 [citation].

Centromochlus dunni Fowler, 1945b: 111 , figs. 11-13 [type locality: Colombia, Morelia, Caquetá river drainage]. Fowler, 1951: 462 [upperAmazon, Colombia]. Rössel, 1962: 20 [no locality]. Lüling, 1963: 50, fig. 15 [Quisto Cocha, Iquitos]. Böhlke, 1984:24 [reference].

Tatia aulopygia . Miranda Ribeiro, 1962: 10 [Amazonas].

Tatia dunni . Ferraris, 2003:476 [checklist]. Ferraris, 2007: 77 [checklist].

Diagnosis. Tatia dunni is distinguished by a unique combination of characteristics: nasal ossified with narrow medial flanges partially sutured to lateral margin of mesethmoid; analfin rays iii, 6-7; modified anal fin in mature males with short tip; first unbranched anal-fin ray with segments fused; last branched ray normally developed, not reduced ( Fig. 21 ); ribs 10; and vertebrae 35. Additional features useful for distinguishing T. dunni include details in coloration, as: contour of mouth dark, same color as head; posterior border of nuchal shield usually dark; pectoral-fin spine usually dark brown; body coloration with irregular blotches or stripes, large specimens with faint stripes or blotches; and caudal fin dark with whitish blotches.

Description. Measured adult specimens 66.1-114.5 mm SL; morphometric data presented in Table 6. Body deep, head depressed dorso-ventrally. Head robust, outline of head in dorsal view somewhat elliptic, slightly broader than long. Trunk from dorsal-fin base to caudal peduncle becoming gradually compressed laterally. Outline of head in dorsal view from snout tip to opercular margin slightly convex until pectoral-fin insertion. Ventral profile of head and abdomen slightly convex. Ventral profile of body compressed behind anal-fin origin. Head integument thin, cranial roof visible; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, upper lip extended posterolaterally as well-developed fleshy rictal fold; anterior nostril tubular, located on anterior border of snout; posterior nostril large, rounded, limited by small skin flap; transverse distance between anterior nostrils proportionally the same as distance between posterior ones in HL. Maxillary barbel short, extending close to posterior margin of postcleithral process; mental barbel short, tips not reaching pectoral-fin base; inner mental barbel about 60.0-90.0% length of outer mentals. Postcleithral process almost reaching vertical through middle or end of dorsal fin. Caudal peduncle deep, depth about 14.1-18.6% SL.

Rostral border of cranium broad with mesethmoid broader than long; premaxilla underneath with synchondral articulation; cranial fontanel elliptical, bounded by mesethmoid and frontal ( Fig. 20 ); nasal ossified with narrow medial flanges partially sutured to lateral margin of mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla about same size of autopalatine; prevomer expanded anteriorly with well developed arrow-shaped lateral processes; jaws of equal size; premaxilla and dentary with three to four rows of conical teeth. First nuchal plate trapezoid; second nuchal plate slightly concave along lateral margins; third nuchal plate curved, projected laterally, with broad tip. Epioccipital process very small.

Suspensorium, hyoid arch, branchial skeleton and opercular bones as in generic description. Suprapreopercle present as short canal bone. Six branchiostegal rays articulated with hyoid arch: four with anterior ceratohyal and two with posterior ceratohyal; last two flattened and expanded.

Five infraorbital bones in incomplete series. Infraorbital 1 flattened with short ventro-lateral process; remaining infraorbitals thin, reduced to canalicular portions. Infraorbitals 2 and 3 close to infraorbital 1, followed by non-ossified portion of canal below eye and by two posterior short canal bones, forming posterior orbital rim. Lateral line on body with ossified canal bones posteriorly to vertical through pelvic fin origin.

Dorsal fin I,4-5, rarely I,4 (n=13); dorsal-fin spine with 13- 15 antrorse serrations along entire anterior margin; posterior margin smooth. Pectoral fin I,5 (n=13); pectoral-fin spine with 17-19 antrorse serrations along anterior margin; 11-13 retrorse serrations along posterior margin; serrations along both margins progressively larger towards spine tip. Pelvic-fin i,5 (n=13), margin rounded. Adipose fin small, origin on vertical through end of anal-fin base. Anal fin iii, 6-7 (n=13); anal-fin pterygiophores in 8 rod-like proximal radials and seven cartilaginous distal radials. Caudal fin forked, lobes with rounded tips, 8+9 principal rays, 11-18 upper procurrent, 11-20 lower procurrent rays (n=13). Pleural ribs 10, attached to consecutive vertebrae. Post-Weberian vertebrae 35 (n=5).

Color in alcohol. Coloration in preserved specimens umber, with rather long longitudinal pale grayish to whitish irregular blotches; dark markings form reticulations; under surface of head and abdomen whitish; fins with darker markings, more contrasted on caudal ( Fowler, 1945b: 111). Dorsal surface of head almost dark brown; posterior part of nuchal shield faint, usually light brown. Contour of lips and anterior nostrils usually dark. Ventral part of head dark brown around chin barbels. Caudal fin dark with whitish spots over lobes.

Figures

Fig. 19. Tatia dunni. (a)ANSP 71705, holotype, male, 83.3 mm SL, Caquetá river drainage, Colombia.(b) FMNH 88187, female, 77.5 mm SL, Conambo river, Ecuador.

Fig. 20. Neurocranium of Tatia dunni,ANSP 71706, paratype, 50.1 mm SL. Dorsal view.Abbreviations: ep, epioccipital; fo, single cranial fontanel, fr, frontal; le, lateral ethmoid; me, mesethmoid; na, nasal; n1, first nuchal plate, n2; second nuchal plate; n3, third nuchal plate; pe, posterior epioccipital process; ps, posttemporal-supracleithrum; pt, pterotic; so, supraoccipital; sp, sphenotic. Scale bar = 1 mm.

Fig. 21. Male modified anal fin of Tatia dunni, holotype, ANSP 71705, 83.3 mm SL. Left side lateral view. Abbreviations: ac, antrorsely curved denticulation; b1, branched first ray; b6, branched sixth ray; dd, deferent duct; rc, retrorsely curved denticulation; tk, tegumentary keel; ui, unbranched first ray; uii, unbranched second ray; uiii, unbranched third ray. Scale bar = 1 mm.