Magdalenichthys yariguies DoNascimiento, Albornoz-Garzón, Méndez-López, Villa-Navarro & Conde-Saldaña, 2025

Magdalenichthys yariguies DoNascimiento, Albornoz-Garzón, Méndez-López, Villa-Navarro & Conde-Saldaña sp. nov.

( Figs 9–10 View Figure 9 View Figure 10 ; Table 1 View Table 1 )

ZooBank registration: urn:lsid:zoobank.org:act:.

Holotype: IAvH-P 22481 ( 67.9 mm SL), Colombia, Santander, El Carmen de Chucurí, quebrada La Concordia, río La Colorada drainage , 06°34’55.2”N 73°35’36”W, 683 m a.s.l.; J.G. Albornoz-Garzón, A. Suárez-Gamboa & G. Caballero, 24 Feb 2018. GoogleMaps

Paratypes: Santander: El Carmen de Chucurí: IAvH-P 17732 ( 1, 41.9 mm SL, 1 c&s, 46.8 mm SL); same locality and collectors as holotype, 22 Feb 2018 GoogleMaps . IAvH-P 17744 ( 2, 40.3–45.8 mm SL, 1 c&s, 53.3 mm SL); same locality and collectors as holotype, 23 Feb 2018 GoogleMaps . IAvH-P 17757 ( 1, 62 mm SL); collected with holotype. GoogleMaps IAvH-P 17769 ( 1, 53.5 mm SL); quebrada La Concordia, río La Colorada drainage , 06°35’17.7”N 73°35’04.8”W, 672 m a.s.l.; J.G. Albornoz-Garzón & G. Caballero, 25 Feb 2018 GoogleMaps . IAvH-P 17792 ( 1, 60.6 mm SL); quebrada La Leona, río La Colorada drainage , 06°34’35.7”N 73°34’30.7”W, 713 m a.s.l.; J.G. Albornoz-Garzón, 26 Feb 2018 GoogleMaps .

Diagnosis: Magdalenichthys yariguies can be distinguished from all its congeners by having 40 vertebrae (vs. 36–37 in M. lundbergi , 32–33 in M. mompox , 38–39 in M. poira ); more principal (segmented) anal-fin rays (11–12 vs. 9–10); and last anal-fin pterygiophore anterior to hemal spine of vertebrae 33–34 (vs. 29–30 in M. lundbergi , 30 in M. poira , 27 in M. mompox ). Magdalenichthys yariguies is distinguished from M. lundbergi and M. mompox by having a longer anal-fin base (15.6–18.1% of SL vs. 11.7–14.4% in M. lundbergi , 9.9–13.5% in M. mompox ). Magdalenichthys yariguies is distinguished from M. lundbergi and M. poira by having the adipose-fin origin posterior to the anal-fin origin (vs. at same vertical). Magdalenichthys yariguies is distinguished from M. mompox and M. poira by number of gill rakers on first arch (3–4 vs. 7–8 in M. mompox , 5–6 in M. poira ); first dorsal-fin pterygiophore inserted posterior to neural spine of vertebra 12 (vs. vertebra 9 in M. mompox , vertebrae 10–11 in M. poira ); more anal-fin pterygiophores (11 vs. 9–10); and fewer branched rays in the upper lobe of the caudal fin (six vs. seven). Magdalenichthys yariguies further differs from M. lundbergi by having fewer rows of dentary teeth (four vs. five or more); shorter caudal peduncle (16.3–19.3% of SL vs. 20.1–24.2%); and longer maxillary barbel (24.2–30.9% of HL vs. 17.5–23%). Magdalenichthys yariguies further differs from M. mompox by having a parabolic contour of the head in dorsal view, with lateral profiles convex (vs. rectangular, with lateral profiles straight); first anal-fin pterygiophore inserted posterior to hemal spine of vertebrae 24–25 (vs. vertebra 21); upper-caudal fin lobe distinctively longer than lower lobe (vs. both lobes subequal); fewer caudal-fin branched rays (13 or fewer vs. 15); narrower cleithral width (12.8–15.2% of SL vs. 15.3–19.1%); longer adipose-fin base (26.2–28.9% of SL vs. 17.5–20.9%); shorter prepelvic distance (35.4–41.5% of SL vs. 42–47.9%); shorter caudal-fin lower lobe (16.3–19.4% of SL vs. 21.9–24.9%); and shorter head (16.7–20.4% of SL vs. 22.9–25.1%). Magdalenichthys yariguies further differs from M. poira by having more branched pectoral-fin rays (eight vs. seven); fewer dorsal procurrent caudal-fin rays (13 vs. 14–16); fewer ventral procurrent caudal-fin rays (13–14 vs. 15–16); smaller eye (7.0–11.7% of HL vs. 11.9–17.8%); and narrower mouth (35.4–41.8% of HL vs. 41.3–53.5%).

Description: Morphometric data in Table 1 View Table 1 . Refer to Figure 9 View Figure 9 for general appearance. Small heptapterine catfish (largest specimen 67.9 mm SL), with elongated body, elliptical in cross-section at dorsal-fin origin (longest axis horizontal), progressively more compressed to caudal region. Dorsal profile slightly convex from snout tip to occipital region, straight immediately posterior from this point to adipose-fin origin, sloping ventrally along adipose-fin base, and slightly ascending along dorsal membrane supported by procurrent caudal-fin rays. Ventral profile of head slightly convex, then straight to pelvic-fin insertion, slightly concave from this point to anal-fin origin, ascending along anal-fin base to origin of procurrent caudal-fin rays and slightly descending along ventral membrane supported by procurrent caudal-fin rays.

Head depressed, parabolic in dorsal view, dorsally covered by thin skin. Cheek filled with muscular mass of adductor mandibulae, but muscle not reaching dorsally onto skull roof. Snout short and rounded. Mouth slightly prognathous. Premaxillary teeth arranged in a rhomboidal patch of 4–5* medial and eight lateral irregular rows of minute conical teeth. Lower jaw slightly longer than upper jaw. Dentary teeth arranged in four irregular rows of minute conical teeth, similar to those on premaxilla. Maxillary barbel reaching distal tip of innermost pectoral-fin ray. Conspicuous groove accommodating anterior part of maxillary barbel along sides of head, delimiting dorsal and lateral regions of head. Bases of outer and inner mental barbels in a straight line. Outer mental barbel reaching pectoral-fin base. Inner mental barbel surpassing branchial opening. Subcutaneous eye small, dorsal in position and slightly longer in horizontal than vertical axis. Anterior naris tubular. Posterior naris closer to anterior margin of eye than to anterior naris, anteriorly bordered by a low fleshy margin. Anterior and posterior internarial widths equal. Nares disposed in a squared arrangement. Branchiostegal membrane free, supported by eight rays and joined to isthmus only at anteriormost point. Gill rakers on first arch 3–4, located along anterior margin of ceratobranchial.

Lateral line canal complete, reaching caudal skeleton. Supraorbital pore s1 medially adjacent to anterior naris; s2 + i2 pore slightly closer to anterior naris ( Fig. 10 View Figure 10 ), at end of posteriorly directed membranous tubule, originating from commissure connecting supraorbital and infraorbital canals, closer to supraorbital canal; s3 pore inside posterior naris, adjacent to its posterior margin, at notch of cutaneous membrane. Contralateral supraorbital canals connected medially by epiphyseal membranous branch, dorsal to middle of anterior fontanel, without superficial pore; s8 pore (parietal branch) arising from a posteriorly directed membranous canal, externally located posterior to eye, at level of medial margin of eye; s4 and s7 branches and pores absent. Infraorbital pore i1 laterally adjacent to anterior naris, between naris and maxillary barbel base; i3 pore posterior to maxillary barbel base; i4 pore at vertical through anterior margin of eye; i5 pore behind vertical through posterior margin of eye; i6 pore posterior to eye, aligned with ventral margin of eye. Pterotic branch (po2) at posterolateral corner of pterotic. Dentary with seven pores of preoperculo-mandibular canal. Submental pores (pm1) paired. Sixth and seventh mandibular pores approximately at same vertical level. Subpreopercular ossicle with one pore (pm8). Preopercle with two pores, anterior pore (pm9) originating from membranous tubule lateral to interopercle and posterior pore (pm10) from membranous tubule passing lateral to ventral portion of opercle. Last preopercular pore (po1 + pm11) at end of membranous tubule, dorsal to dorsoposterior portion of opercle. Axillary branch (ll1) ventral, running posterior to supracleithrum.

Precaudal vertebrae 11 (1)–12 (1), thoracic vertebrae 9, and caudal vertebrae 28 (1)–29 (1), totalling 40 vertebrae. Ribs seven or eight (last pair shortest). Pectoral fin with i,8 rays. First pectoral-fin ray (unbranched) soft and shorter than first branched ray. First branched ray longest. Distal margin of pectoral fin convex. Pelvic fin with i,5 rays. First pelvic-fin ray (unbranched) thick and shortest, second and third branched rays longest. Pelvic-fin origin opposite to dorsal-fin origin, at vertical through vertebra 14 or 15. Dorsal fin lacking spinelet, with one unbranched and six branched rays, supported by seven pterygiophores. Dorsal-fin margin convex, its unbranched ray slightly shorter than first branched ray; first three branched rays subequal. First dorsal-fin pterygiophore inserted posterior to neural spine of vertebra 12 and last pterygiophore anterior to neural spine of vertebra 17. Adipose fin long, almost rectangular with attenuated ends and posterior lobe free. Adipose-fin origin at vertical through second unbranched ray of anal fin. Anal fin with 2–3 procurrent (unsegmented) rays, and 3* (5)–4 (2) unbranched and 8* (6)–9 (2) branched rays for a total of 11 (5) or 12 (3) principal rays. Anal-fin distal margin rounded. Anal fin supported by 11 pterygiophores. First anal-fin pterygiophore posterior to hemal spine of vertebrae 24 (1)–25 (1) and last pterygiophore anterior to hemal spine of vertebrae 33 (1)–34 (1). Caudal fin deeply forked with i,6 + 7,i* principal rays (one c&s specimen with six branched rays in the lower lobe). Upper lobe of caudal fin conspicuously longer than lower lobe, both lobes pointed. Procurrent caudal-fin rays 13 dorsal and 13–14 ventral, located posterior to vertebrae PU 6. Posteriormost four procurrent caudal-fin rays segmented. Caudal skeleton PH + 1 + 2,3 + 4 + 5. Long epural present.

Pigmentation in alcohol: Overall ground coloration marbled. Minute and numerous melanophores clustered at humeral region, forming posteriorly a midlateral inconspicuous stripe extending to caudal-fin base. Myosepta delineated by chromatophores, more evident above anal-fin base. Dorsal surface of head and predorsal area darker than remaining surface of body. Dark streak extending dorsally on surface of snout, between base of maxillary barbel and anterior margin of eye. Conspicuous and narrow pale band with roughly M-shaped, posterior to head, between dorsal corners of branchial openings. Cheeks and maxillary groove lighter than remaining surface of head, peppered with sparse chromatophores. Basal portion of maxillary barbel darkly pigmented on dorsal surface. Base of dorsal fin with a dark band along sides. Ventral surface of head with anterior crescent shaped dusky area fading posteriorly, isthmus and branquiostegal membrane pale. Abdomen pale, sparse chromatophores posterior to ventral fins. Adipose fin with marbled pattern of chromatophores. Dorsal-fin rays with chromatophores. Basal portion of pectoral and pelvic-fin rays with chromatophores.Base of anal-fin rays with chromatophores. Caudal-fin rays with minute chromatophores, giving diffuse dark pigmentation. Interradial membrane of fins hyaline.

Distribution: This species is restricted to the La Colorada River drainage, a direct tributary of the middle section of the Magdalena River basin ( Fig. 4 View Figure 4 ).

Habitat and ecological notes: The type locality of Magdalenichthys yariguies is a stream with an average width of 7 m, substrate of sand, pebbles, and rocks, and margins with abundant riparian vegetation ( Fig. 11 View Figure 11 ). Specimens of M. yariguies were found syntopically with Hoplias malabaricus (Bloch, 1794) , Lebiasina floridablancaensis Ardila Rodríguez, 2001 , Astyanax yariguies ( Torres-Mejia, Hernández & Senechal, 2012) , Creagrutus guanes Torres-Mejia & Vari, 2005 , Creagrutus magdalenae Eigenmann, 1913 , Hemibrycon plutarcoi (Román-Valencia, 2001) , Hemibrycon sp. , Knodus sp. , Trichomycterus calai Ardila Rodríguez, 2019 , Trichomycterus cf. transandianus (Steindachner, 1915) , Trichomycterus sp. , Astroblepus cf. verai Ardila Rodríguez, 2015 , Farlowella yarigui Ballen & Mojica, 2014 , Dolichancistrus carnegiei (Eigenmann, 1916) , Lasiancistrus volcanensis Dahl, 1941 , Pimelodella floridablancaensis , Poecilia caucana (Steindachner, 1880) , and Geophagus steindachneri .

Etymology: The name yariguies honours the exterminated indigenous group that inhabited the río Cascajales drainage. Used as a noun in apposition.