Trichomycterus tetuanensis, García-Melo, Luis J., Villa-Navarro, Francisco A. & Donascimiento, Carlos, 2016

García-Melo, Luis J., Villa-Navarro, Francisco A. & Donascimiento, Carlos, 2016, A new species of Trichomycterus (Siluriformes: Trichomycteridae) from the upper río Magdalena basin, Colombia, Zootaxa 4117 (2), pp. 226-240 : 228-236

Trichomycterus tetuanensis , new species

( Figs. 1–3 , Table 1 )

Trichomycterus striatus (non Meek & Hildebrand, 1913): Maldonado-Ocampo et al., 2005: 112 [description, listing of cataloged specimens].

Holotype. CZUT-IC 5151 (57.2 mm SL), Colombia, Tolima, Ortega, río Tetuán, upper río Magdalena basin, 03°51’23.866”N 75°16’47.508”W, elevation 374 m, 6 Jun 2003, A. Ortega-Lara, F. A. Villa-Navarro and J. García- Melo.

Paratypes. CZUT-IC 883 (5, 62.6–96.1 mm), Colombia, Tolima, Ortega, río Peralonso, 03°52’16.074”N 75°16’21.51”W, elevation 383 m, 7 Jun 2003, A. Ortega-Lara, F. A. Villa-Navarro and J. García-Melo; CZUT-IC 904 (9, 43.1–78.6 mm SL; 2 cs, 47.4–50.9 mm SL), IAvH-P 12753 (1, 67.6 mm SL; 1 cs, 63.5 mm SL), collected with the holotype; CZUT-IC 896 (7, 59.7–82.7 mm SL), same locality and collectors as holotype, 5 Oct 2003.

Diagnosis. Trichomycterus tetuanensis is distinguished from most congeners by its emarginate caudal fin ( Fig. 1 ), which, with the single exception of Trichomycterus banneaui , is either round or truncate in the remaining trans- Andean species from Colombia. Trichomycterus tetuanensis differs from T. banneaui in its larger size (96.1 mm SL vs. 44.0 mm SL), pigmentation pattern (background light brown with darker dots smaller than eye diameter, uniformly sparse on dorsum and sides of trunk vs. background yellow with predorsal and horizontal mid-lateral rows of large blotches), higher number of premaxillary teeth rows (three vs. two), higher number of branchiostegal rays (eight vs. seven), higher number of free vertebrae (37 vs. 34), and hypural 3 separated from hypural plate 4+5 (vs. fused). The new species is additionally distinguished from most of its congeners by its high number of opercular odontodes (21–39 vs. 30 or less odontodes), arranged in 6-8 dorsoventral transverse rows, and evident as an externally conspicuous large opercular patch of odontodes ( Fig. 2 ).

Description. Morphometric data presented in Table 1 . Body elongated, deeper than wide in trunk region, gradually compressed to caudal-fin base ( Figs. 1 , 3 ). Dorsal profile of head straight; trunk slightly convex just posterior to head to dorsal-fin origin; straight to slightly concave along dorsal-fin base; anterior region of caudal peduncle straight, sloping dorsally along most anterior part of caudal fin. Ventral profile of head straight to slightly convex; trunk slightly concave to straight at pectoral-fin insertion; straight to slightly convex just posterior to this point to pelvic-fin base; straight and sloping dorsally to anal-fin origin; anterior region of caudal peduncle concave, then continuing as a ventrally sloping straight line along most anterior part of caudal fin. Cross-section of body approximately oval at pectoral-fin base.

Head depressed, longer than wide, triangular in dorsal view. Cheek muscles slightly bulging externally in lateral contour of head. Eye small, dorsolateral on middle of head. Eye rim not free, covered by thin and translucent skin, continuous with head skin. Mouth subterminal, relatively narrow. Upper lip with minute papillae immediately anterior to premaxillary teeth. Lower lip with large rectangular lateral lobes located posteromedially to rictal barbel base. Premaxillary teeth conical, arranged in three irregular rows. Dentary teeth conical, similar in size to those of premaxilla, arranged in three irregular rows near symphysis and one row to posterior region of dentary. Anterior nostril medially surrounded by fleshy flap, increasingly deeper posteriorly and laterally continuous with nasal barbel. Posterior nostril closer to anterior nostril than to eye; anterior rim delimited by thin fleshy elevated margin; posterior rim not delimited by fleshy flap, and continuous with head surface. Barbels long and flattened, tapering distally. Nasal barbel originating laterally from fleshy fold encircling anterior nostril and extending posteriorly to half-length of opercular patch of odontodes. Tip of maxillary barbel surpassing pectoral-fin base. Rictal barbel slightly shorter than maxillary barbel, with its tip reaching posterior region of pectoral-fin base. Interopercle with 42–52 odontodes, arranged in three irregular rows. Posterior interopercular odontodes of medial row largest, with distal tip medially curved. Opercular patch of odontodes large and almost circular in shape, with 21–39 conic odontodes arranged in 6–8 dorsoventral transverse rows. Opercular odontodes gradually larger posteriorly. Branchiostegal membrane supported by eight rays and joined to isthmus only anteriorly, forming a narrow free fold across isthmus. Medial most three branchiostegal rays associated with anterior ceratohyal, next three rays with interceratohyal cartilage and lateral most two rays with posterior ceratohyal. Branchiostegal rays 5–8 expanded distally ( Fig. 4 ), branchiostegal ray 6 with greatest distal expansion (four times as wide as distal tip of ray 7). Gill opening wide.

Anterior margin of mesethmoid straight ( Fig. 5 ). Anterior fontanel small, oval (ca. 15% of posterior fontanel length). Epiphyseal bar entirely osseous, not meeting medially. Posterior fontanel long, rectangular, extending from epiphyseal bar to approximately last third of parieto-supraoccipital. Lachrymal/antorbital associated with anterior section of infraorbital canal (sensory pores i1 and i3). Sesamoid supraorbital long (ca. four times longer than lachrymal/antorbital), lacking lateral processes. Anterior portion of sphenotic anterolaterally directed. Vomer arrow-shaped with a pair of short processes posterolaterally directed. Parasphenoid with long posterior process that reaches anterior region of basi-exoccipital. Basi-exoccipital with a pair of short anterior membranous processes, laterally adjacent to posterior process of parasphenoid. Premaxillary bone rectangular and relatively short. Autopalatine with medial margin concave and posterolateral process long and pointed. Metapterygoid small, triangular. Hyomandibula with well-developed anterodorsal membranous outgrowth, its dorsal margin smooth and concave along anterior region. Basibranchials 2 and 3 and hypobranchial 1 rod-like of similar length. Basibranchial 2 wider than basibranchial 3. Basibranchial 4 cartilaginous hexagonal plate. Hypobranchial 1 slightly concave along posterior margin, lacking processes. Ossified portion of hypobranchial 2 approximately triangular and anterolaterally oriented, representing ca. 40% of entire hypobranchial. Hypobranchial 3 trapezoidal, with triangular ossified portion anterolaterally oriented, representing ca. 10% of entire hypobranchial. Ceratobranchial 5 with 18- 22 conical teeth aligned in three irregular rows along anteromedial margin of bone, increasing in size medially. Epibranchial 1 with long anterior uncinate process anterolaterally directed and short posterior process at distal region. Epibranchial 2 with anterior uncinate process (ca. 40% of length of anterior uncinate process of epibranchial 1) and short triangular posterior process at distal portion. Epibranchial 3 with proximal portion curved and a dorsally curved posterior uncinate process, proximate to its distal end. Epibranchial 4 broad with anterior and posterior crests giving a rectangular aspect. Upper tooth plate supporting a patch of 30–32 conic teeth, increasing in size posteriorly, arranged in two irregular rows.

Supraorbital sensory canal continuous with three pores, lacking a medial commissure at level of epiphyseal bar ( Fig. 5 ). Sensory pore s1 located medially adjacent to anterior nostril. Sensory pore s3 medial to posterior nostril, at level of its posterior margin. Sensory pore s6 paired, medial and posterior to eye. Pores s6 closer to mid-sagittal plane than to eye and slightly asymmetrical in anteroposterior position, being one pore slightly in advance to its counterpart. Infraorbital sensory canal interrupted in two sections; anterior section with sensory pores i1 and i3 and posterior section with sensory pores i10 and i11. Sensory pore i1 laterally adjacent to anterior nostril and i3 lateral to anterior region of posterior nostril. Sensory pore i10 posterolaterally adjacent to eye and i11 posterior and horizontally aligned to eye. Terminal sensory pore of preopercular canal anterodorsal to opercular patch of odontodes. Sensory pore of pterotic branch just dorsal to opercular patch of odontodes and concealed by dorsal margin of opercular fold. Lateral line canal short with two pores above pectoral-fin base. Sensory pore ll1 ventral to main lateral line canal and ll2 terminus of main lateral line canal, extending up to posterior end of pectoral-fin base.

Precaudal free vertebrae 5–6 and caudal vertebrae 30–31, totaling 37 vertebrae. First 10–11 vertebrae bearing ribs. First hemal spine on vertebra 13–14. Skin of body with minute papillae, visible only under stereomicroscope. Anus at vertical through base of second branched dorsal-fin ray. Anus and urogenital papilla closer to anal-fin origin than to pelvic-fin base.

Pectoral fin with i,7 rays. First ray longest, projected beyond margin of fin as a moderately long filament (filamentous portion ca. 1/3 of respective fin ray length). Posterior margin of pectoral fin rounded. Pectoral complex radial cartilaginous ( Fig. 6 ). Scapulocoracoid with long anterior slender process ending in pointed tip.

Pelvic fin with i,4 rays and relatively long lateral splint with relatively long anterior portion, forming obtuse angle with posterior portion aligned to anteroposterior axis. First and second branched rays longest. Inner margins of pelvic-fin bases close to each other (internal distance ca. 30% of fin base). Posterior margin of fin rounded, reaching anus. Basypterigium with two long anterior processes approximately of same length (left basypterigium of one cs paratype, 50.9 mm SL, with a broad base short anterior process, adjacent to pelvic symphysis). Short distally rounded posterior process at posteromedial corner of basypterygium.

Dorsal fin with three procurrent rays and ii,7 principal rays. Distal margin straight to slightly convex. First branched ray longest. Origin of fin at vertical through last third of pelvic fin. Supporting elements of dorsal fin represented by eight basal radials and six distal radials. Distal radials associated with second to penultimate basal radials. First pterygiophore inserted posterior to neural spine of vertebrae 18–20. Last pterygiophore inserted anterior to neural spine of vertebrae 22–23.

Anal fin with three procurrent rays and ii,5 principal rays. Base of anal fin shorter than dorsal-fin base. Distal margin of fin almost straight. First branched ray longest. Origin of fin through vertical between base of third and fourth branched dorsal-fin rays. Fin rays supported by six basal radials and four distal radials. Distal radials associated with second to penultimate basal radials. First pterygiophore inserted posterior to hemal spine of vertebrae 22–23. Last pterygiophore inserted anterior to hemal spine of vertebra 25.

Caudal fin emarginate with i, 5+6, i principal rays. Outermost branched rays of dorsal and ventral lobes distinctly longest. Dorsal procurrent rays 14, inserted posterior to neural spine of vertebra 31. Ventral procurrent rays 11, inserted posterior to hemal spine of vertebra 32. Caudal skeleton with three plates; ventral plate represented by parhypural fused to hypurals 1 and 2, middle plate by hypural 3, and dorsal plate by fused hypurals 4 and 5. Hypurapophysis type C ( Lundberg & Baskin, 1969). Epural absent. Neural spine of compound caudal vertebra complete and relatively short (ca. 1/3 of length of preceding neural spine).

Coloration in ethanol. Ground color of dorsum of head and body and sides of body light brown, ventral surface of head and belly lighter. Dark diffuse dots irregularly scattered on dorsum, dorsolateral region of trunk anterior to pelvic fin insertion, and entire flank including caudal peduncle, just posterior to pelvic fins. Faint dark band along midline from behind opercle to base of caudal fin, continuous posteriorly with darkly pigmented middle caudal-fin rays. Nasal barbel and upper surface of maxillary barbel darkly pigmented. Dorsal surface of head except cheek region darker than ventral surface. Cheek and dorsolateral surface of head, immediately posterior to eye and anterior to opercular patch, lighter than remainder of dorsal surface of head. Opercular and interopercular patches dark with dense blotches of chromatophores. Dorsal surface of pectoral and pelvic-fin rays with chromatophores aligned along their margins. Dorsal, anal, and caudal-fin rays with chromatophores delineating margins of rays. Interradial membranes of fins light brown and translucent, except basal portion of caudal fin with chromatophores densely clustered.

Coloration in life. Ground color greenish yellow with light purple iridescence along flanks ( Fig. 3 ). Dense layer of darker dots uniformly scattered on dorsum and sides of head and body, only cheek region free of dots. Etymology. The specific epithet “ tetuanensis ” refers to the río Tetuán, type locality of the species.

Distribution. Trichomycterus tetuanensis is only known from the río Tetuán and its main tributary the río Peralonso ( Fig. 7 ). The río Tetuán is a lowland river ( Fig. 8 ) that empties into the río Saldaña of the upper basin of the río Magdalena, on the east versant of the Cordillera Central of Colombia. The new species is sympatrically found with T. banneaui , which is widely distributed in the upper basin of the río Magdalena ( García-Melo, 2009).

Figures

FIGURE 1. Holotype of Trichomycterus tetuanensis, CZUT-IC 5151, 57.2 mm SL; Colombia, Tolima, Ortega, río Tetuán, upper río Magdalena basin, 03 ° 51 ’ 23.866 ” N 75 ° 16 ’ 47.508 ” W (scale bar = 1 cm).

FIGURE 2. Left opercle (lateral view, anterior to the left) of Trichomycterus tetuanensis, paratype, CZUT-IC 904, 50.9 mm SL. Abbreviations: dp, dorsal process; op, opercular plate of odontodes; vp, ventral process (scale bar = 1 mm).

FIGURE 3. Live paratype of Trichomycterus tetuanensis, CZUT-IC 904, Colombia, Tolima, Ortega, río Tetuán, upper río Magdalena basin, 03 ° 51 ’ 23.866 ” N 75 ° 16 ’ 47.508 ” W (photo by J. E. García-Melo).

FIGURE 4. Dorsal view (anterior to top) of hyoid arch of left side of Trichomycterus tetuanensis, paratype, CZUT-IC 904, 50.9 mm SL. Abbreviations: ac, anterior ceratohyal; br, branchiostegal rays; lpu, lateral process of parurohyal; pc, posterior ceratohyal; pu; parurohyal; ppu, posterior process of parurohyal; vh, ventral hypohyal (scale bar = 1 mm).

FIGURE 5. Dorsal view of cranium and Weberian capsule of Trichomycterus tetuanensis, paratype, CZUT-IC 904, 50.9 mm SL. Abbreviations: af, anterior fontanel; au, autopalatine; ep, epioccipital; fr, frontal; i 1, i 3, i 10 - 11, infraorbital sensory pores 1, 3, and 10 – 11; la, lachrymal / antorbital; le, lateral ethmoid; me, mesethmoid; mx; maxilla; pf, posterior fontanel; pm, premaxilla; pr, sensory pore of preopercular canal; pt, pterotic; pt b, sensory pore of pterotic branch; pte + sp + pro, pterosphenoid + sphenotic + prootic compound bone; ptts, posttemporo-supracleithrum; sob, sesamoid supraorbital; su, parietosupraoccipital; s 1, s 3, s 6, supraorbital sensory pores 1, 3, and 6; wc, Weberian capsule (scale bar = 1 mm).

FIGURE 6. Ventral view of left pectoral girdle and fin of Trichomycterus tetuanensis, paratype, CZUT-IC 904, 50.9 mm SL. Abbreviations: cl, cleithrum; cr, complex radial; pr, pectoral radial; sca, scapulocoracoid; sca pr, scapulocoracoid process (scale bar = 1 mm).

FIGURE 7. Maps of Departamento del Tolima and Municipio de Ortega, showing collecting localities of Trichomycterus tetuanensis (type locality star).

FIGURE 8. Type locality of Trichomycterus tetuanensis, río Tetuán (03 ° 51 ’ 23.866 ” N 75 ° 16 ’ 47.508 ” W), Ortega, Tolima, Colombia, 6 June 2003. Photograph by Jorge E. García-Melo.

Tables

TABLE 1. Morphometric data for holotype and nine paratypes of Trichomyterus tetuanensis. Measurements 2 – 13 expressed as percentage of standard length and 14 – 23 as percentage of head length. x = arithmetic mean, R = range, and SD = standard deviation.

	Holotype	x	R SD
1. Standard length	57.2	–	43.3–96.1 –
2. Total length	117.0	116.2	112.6–118.5 –
3. Body depth	14.5	14.4	12.2–15.8 0.9
4. First pectoral-fin ray	21.2	17.8	8.4–23.0 2.9
5. Second pectoral-fin ray	14.3	13.2	11.5–15.2 0.9
6. Predorsal length	67.8	67.4	65.5–69.8 1.0
7. Preanal length	73.1	74.2	72.5–76.3 1.1
8. Prepelvic length	58.7	58.3	56.2–60.0 1.2
9. Dorsal-fin base	12.6	11.4	10.3–12.7 0.7
10. Anal-fin base	7.9	7.7	7.0–8.8 0.5
11. Caudal-peduncle length	17.1	18.1	16.4–20.2 0.9
12. Caudal-peduncle depth	9.8	10.8	8.7–11.8 0.7
13. Head length	19.4	19.0	17.4–20.2 0.7
14. Head width	86.5	83.0	75.7–91.5 4.1
15. Head depth	42.3	43.5	33.2–55.6 5.7
16. Snout length	42.3	41.8	38.5–45.4 1.7
17. Mouth width	36.9	34.2	28.7–39.6 2.9
18. Interorbital distance	27.0	26.1	22.4–29.5 2.3
19. Eye diameter	8.1	7.7	6.7–8.7 0.6
20. Maxillary barbel length	95.5	79.3	51.7–95.8 13.2
21. Nasal barbel length	84.7	66.2	46.1–86.3 12.1
22. Rictal barbel length	76.6	61.3	37.4–76.6 11.7
23. Interopercular patch length	35.1	33.5	30.2–37.6 2.1