Tatia gyrina (Eigenmann & Allen, 1942)

Sarmento-Soares, Luisa Maria & Martins-Pinheiro, Ronaldo Fernando, 2008, A systematic revision of Tatia (Siluriformes: Auchenipteridae: Centromochlinae), Neotropical Ichthyology 6 (3), pp. 495-542 : 519-522

Tatia gyrina (Eigenmann & Allen, 1942) Figs. 2-5 , 25-26

Centromochlus aulopygius . Eigenmann & Eigenmann, 1888: 157 [Cudajas (Codajás)]. Eigenmann & Eigenmann, 1890: 270 [distribution]. Eigenmann & Eigenmann, 1891: 34 [listing].

Centromochlus gyrinus Eigenmann & Allen, 1942: 118 , pl.5 fig. 4 [type locality: Peru, Iquitos, brook near Itaya river]. Gosline, 1945: 10 [listing]. Fowler, 1945a: 62 [Iquitos]; Fowler, 1945b: 112 [listing]; Fowler, 1951: 462, fig. 491 [literature compilation].

Centromochlus creutzbergi Boeseman, 1953: 7 , fig. 1c [type locality: Djaicreek (Djao stream)]. New synonym. - Hoedeman, 1957:151, fig. 8 [Coropina stream near Republiek].- Rössel, 1962: 30 [no locality].- Hoedeman, 1968: 148 [ Suriname].

Tatia gyrina . Mees, 1974: 74-75 [notes on holotype and distribution]. Ortega & Vari, 1986:14 [reference]. Burgess, 1989:242 [reference]. Soares-Porto, 1995:205 [citation]. Soares-Porto, 1998: 333 [citation]. Ferraris, 2003:477 [checklist]. Ferraris, 2007: 77 [checklist].

Tatia creutzbergi . Mees, 1974: 77-80, fig. 18 [notes and distribution, northern Suriname lowlands and Cudajas (=Codajás), Brazil]. Sands, 1984: 40 [listing]. Mees, 1985: 241 [northern Suriname]. Mees, 1988: 410 [Para stream and Kaboeri stream, Suriname]. Burgess, 1989:242 [reference]. Soares-Porto, 1995:205 [citation].Chang & Ortega, 1995:4 [reference]. Soares-Porto, 1998: 333 [citation]. Ferraris, 2003:476 [checklist]. Ferraris, 2007: 77 [checklist].

Diagnosis. Tatia gyrina is distinguished from all other species of Tatia by its reduced mesethmoid, wider than long, (mesethmoid length 12.1-15% HL; width 17.2-19% HL); lower jaw slightly protruding beyond upper; nasal ossified, tubular, not sutured to mesethmoid; third nuchal plate reduced ( Fig. 3, n3 ); small prevomer, with short rostro-lateral process; elongate postcleithral process, sometimes as long as head length; ribs 5-6 (vs. 7-11 in other Tatia ); and vertebrae, 29-30 (vs. 31-39 in other Tatia , except T. galaxias , that rarely has 30). Mature males have an externally elongate deferent duct and a swollen anal-fin base, with a thick secretory pouch ( Fig. 26 , tp). The species is also distinguished by the following combination of restricted characteristics: females with genital papilla; anal fin of mature males bearing rays with uncurved segments; and caudal fin lobes with about the same length in both adult females and males. Additional features useful for distinguishing T. gyrina has a whitish ground color pattern with brown spots, pattern mottled or with irregular stripes; ventral surface of head covered with short brown irregular stripes; body with a characteristic dark band along lateral line; and a small adult size of less than 40 mm SL.

Description. Measured adult specimens 28.0- 38.2 mm SL; morphometric data presented in Table 8. Body short, head slightly depressed dorso-ventrally. Head large, robust, outline of head in dorsal view somewhat rectangular, broader than long. Dorsal outline of trunk from dorsal-fin base to caudal peduncle gradually compressed posteriorly. Lateral profile of head from snout tip to above opercular margin slightly convex until pectoral-fin insertion. Ventral profile of head and abdomen flat. Ventral profile of body concave posterior to anal fin.

Head integument thin, cranial roof visible; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, lower jaw slightly protruding beyond upper, upper lip extended postero-laterally as well-developed fleshy rictal fold; snout margin rounded, in dorsal view; anterior nostril tubular, located on anterior border of snout; posterior nostril large, rounded, limited by well developed skin flap; transverse distance between anterior nostrils shorter than distance between posterior ones. Maxillary barbel of moderate size, extending beyond opercular membrane, reaching vertical through middle dorsal fin; Four mental barbels, tips not reaching pectoral-fin base, arranged in arc along ventral surface of jaw; innermentalbarbelabout 50.0-67.0% lengthofoutermentals. Postcleithral process well developed, almost reaching vertical through middle or end of dorsal fin. Caudal peduncle moderately deep, its depth about 11.3-13.2% SL.

Rostral border of cranium thin with small mesethmoid, larger than long; premaxilla underneath with synchondral articulation; cranial fontanel large, rounded, bounded by mesethmoid and frontal ( Fig. 2 ); nasal ossified as short tubular canal bone, lying between mesethmoid cornua and lateral ethmoid, not sutured to mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla small, shorter than autopalatine; prevomer reduced, with short lateral process. Discrete prognathous mandibula; premaxilla and dentary with two to three rows of conical teeth. First nuchal plate trapezoid; second nuchal plate short; third nuchal plate short, with tips projected laterally. Epioccipital process very small.

Suspensorium and opercular bones ( Fig. 2 ); hyoid arch ( Fig. 4 ) and branchial skeleton ( Fig. 5 ) as in generic description. Suprapreopercle present as short canal bone. Five to seven slender branchiostegal rays articulated with hyoid arch: three to five with anterior ceratohyal and two with posterior ceratohyal; last one expanded. Basibranchial 2 forming osseous rod with broad cartilaginous anterior tip, separated from shorter basibranchial 3.

Five to six infraorbital bones in incomplete series. Infraorbital 1 thin, with short ventro-lateral process; remaining infraorbitals thin, reduced to canalicular portions. Infraorbital 2 and/or 3 small, close to infraorbital 1, followed by nonossified portion of canal below eye and two posterior canal bones, forming posterior orbital rim. Lateral line on body with 3-5 ossified canal bones only close to head.

Dorsal fin I,3-5 (n=19), usually 4 (three branched only in T. creutzbergi holotype and five branched in oneAMNH 105.832 specimen). Dorsal-fin spine with 10-15 antrorse serrations along entire anterior margin, posterior margin smooth. Pectoral fin I,4 (n=21); pectoral-fin spine with 17-23 antrorse serrations along anterior margin; 9-13 retrorse serrations along posterior margin; serrations along both margins progressively larger towards spine tip. Pelvic fin i,5 (n=21); margin rounded. Adipose fin large, origin on vertical through middle of analfin base. Anal fin ii-iii, 6-7 (n=21); anal-fin pterygiophores in eight rod-like proximal radials and seven cartilaginous distal radials. Caudal fin slightly emarginated, lobes with rounded tips, 8+9 principal rays, 8-20 upper procurrent, 10-21 lower procurrent rays (n=21). Pleural ribs 5-6 attached to consecutive vertebrae. Post-Weberian vertebrae 29-30 (n=9).

Color in alcohol. Illustration in Eigenmann & Allen (1942: 439, fig. 4), shows holotype of T. gyrina as originally mottled brown, without dark lateral band, and specimen described as spotted and streaked (Eigenmann & Allen, 1942: 118). Preserved holotype now faded and, based on recent examination of specimen, has only traces of pigmentation, consisting of small brown chromatophores on dorsal and caudal fins. Species coloration described as follows ( Fig. 25 ): Dorsal surface of head and dorsal fin dark brown; head irregularly striped in brown ventrally; sides of body mottled with numerous irregular spots; usually dark brown stripe along lateral line; body usually yellowish ventrally; pectoral-fin spine usually with transverse dark bands; adipose fin pale brown; caudal fin spotted with dark band on center of each lobe. Sands (1984: 40) illustrated a living specimen of T. gyrina .

Color variation. Variation in body pigmentation was observed between the Suriname and Amazonian populations. In Suriname specimens the body is usually yellowish ventrally or sometimes with a rounded brown spot present near each pelvic-fin base. No Amazon specimens had a rounded brown spot near the pelvic-fin base and the body is invariably yellowish ventrally. Variation in pectoral-fin spine pigmentation occur independent of geographical locality: pectoral-fin spine is usually transversely banded but is uniformly dark to unpigmented in some specimens. Coloration of the dark lateral stripe on the side of the body varies. In some Suriname specimens (ZMA 105.832) the dark brown lateral stripe has irregular dark and light areas. In addition, the lateral stripe was interrupted in some and absent in decolorized specimens. In an upper Amazon specimen (FMNH 94752), the lateral stripe is light brown, not as dark as in the Amazon specimens.

Tatia gyrina occasionally occur together with T. strigata and in these situations the two species are remarkably similar in appearance. The situation is exacerbated by the fact that T. strigata taken with T. gyrina have a dark lateral stripe, a character otherwise rare in T. strigata . In these instances, the main way to distinguish the two species is by certain head measurements. Tatia gyrina has a deep (snout depth 50.0- 59.4% HL), and broad head (head width 82.4-94.2% HL) and prognathous lower jaw; whereas T. strigata has a shallow (snout depth 41.3-47.3% HL) and narrow head (head width 70.1-76.7% HL), and jaws of equal sizes. There are also some minor color differences. The sides of body in T. gyrina are mottled, with variations in form and size of the individual spots, but never striated or striped like in T. strigata . Furthermore in T. strigata the stripes are long, almost horizontal and narrow.

Sexual dimorphism. Based on examination of gonads, T. gyrina attains sexual maturity above 28.0 mm SL. In mature females a genital papilla is evident, with the genital opening close to the anal-fin origin, emerging from a slender fleshy process.A female genital papilla is rare within Tatia . The genital papilla of mature male is evidenced by a swollen anal-fin base ( Fig. 26 ). Dissection revealed the presence of a thick pouch inside it, formed by broad mass of some glandular tissue, with secretory material.A unique male deferent duct is present, externally elongate, thick and emergent ( Fig. 26 , dd). The extended deferent duct is also seen in young males, permitting the distinction between sexes even in juveniles. This condition is uniquely found in T. gyrina males. In other Tatia , as well as in most centromochlins, only short slender tip of deferent duct is externally visible, emerging from genital papilla.

The mature male modified anal fin ( Fig. 26 ) is short, with a small tip, and three enlarged and thickened unbranched analfin rays. First unbranched ray with the segments fused or bearing a single median one in one specimen ( CAS 36979), and is immediately preceded by a short tegumentary keel ( Fig. 26 , tk). The second and third unbranched rays are converging with first branched to form a short anal-fin tip ( Fig. 26 , uiii). No curved segments are associated with the anterior rays. The posterior branched rays are normally developed, with the last ray not reduced ( Fig. 26 , b 7 ) .

Hemal spines 13-16 interdigitate with the anal-fin pterygiophores, being the hemal spines 14-16 thickened in mature males, but undifferentiated in females. Minor sexual dimorphism is observed in male caudal fin: upper lobe of some males is slightly elongate, about 10% longer than lower one. The caudal-fin lobes have same length in mature females.

Distribution. Tatia gyrina occurs in the upper and central Amazon, in Peru, Colombia and Brazil. It is also found in rivers of northern Suriname ( Fig. 6 ).

Figures

Fig. 2. Right suspensorium of Tatia gyrina, INPA 20971, 28.0 mm SL. Lateral view.Abbreviations: aa, angulo-articular; dn, dentary; hy, hyomandibula; io, interopercle; mt, metapterygoid; op, opercle; po, preopercle; qu, quadrate; sb, subpreopercle; sp, suprapreopercle. Scale bar = 1.0 mm.

Fig. 3. Neurocranium of Tatia gyrina, INPA 20971, 28.0 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-supracleitrum; pt, pterotic; so, supraoccipital; sp, sphenotic. Scale bar = 1.0 mm.

Fig. 4. Right hyoid arch of Tatia gyrina, INPA 20971, 28.0 mm SL. Medial view. Abbreviations: ac, anterior ceratohyal; br, branchiostegal rays; dh, dorsal hypohyal; ic, interceratohyal cartilage; ih, interhyal; pc, posterior ceratohyal; vh, ventral hypohyal; uh, urohyal. Scale bar = 1.0 mm.

Fig. 5. Pharyngeal arches of Tatia gyrina, INPA 20971, 28.0 mm SL. Dorsal view. Abbreviations: ab, anterior (first) basibranchial; bb2, basibranchial 2; bb3, basibranchial 3; bb4, basibranchial 4; cb1-5, ceratobranchials 1 to 5 (anterior to posterior); eb1-4, epibranchials 1 to 4 (anterior to posterior); hb1-3, hypobranchials 1 to 3; pb3, pharingobranchial 3; pb4, pharingobranchial 4. Scale bar = 1.0 mm..

Fig.25. Tatia gyrina. (a) ZMA 105.859, male, 30.1 mm SL, Carolina stream, Suriname.(b) INPA 20971, female, 26.0 mm SL, Tefé, Amazonas State, Brazil.

Fig. 26. Male modified anal fin of Tatia gyrina, INPA 20971, 28.0 mm SL.Left side lateral view.Abbreviations:b7, branched seventh ray; dd, deferent duct; tp, thick secretory pouch; tk, tegumentary keel; ui, unbranched first ray; uii, unbranched second ray; uiii, unbranched third ray. Scale bar = 1 mm.

Fig. 7. Tatia aulopygia, (a) INPA 11080, male, 104.6 mm SL, Guaporé river, Amazonas State, Brazil. (b) ZMA 114.280, young female, 46.3 mm SL, Humaitá,Amazonas State, Brazil.

Fig. 6. Drainage map of northern South America illustrating the geographic distribution of the species of Tatia. Symbols may represent more than one locality. Base map by Marilyn Weitzman.