Rineloricaria giua, Castellanos-Mejía & Londoño-Burbano & Ochoa & García-Alzate & DoNascimiento, 2024

Rineloricaria giua , new species urn:lsid:zoobank.org:act:BE1D29DD-D863-414B-B6E2-13DA6F768221

Figures 1B View FIG , 4 View FIG , 5 View FIG ; Table 1

Holotype.— CIUA 8680 , male, 79.5 mm SL, Colombia, Cesar, La Jagua de Ibirico, Tucuy River, Magdalena River Basin , 9835 0 13 00 N, 73818 0 34.9 00 W, 122 m a.s.l., V. M. Medina, J. G. Ospina, and D. Restrepo, 9 September 2023.

Paratypes.— Colombia: Magdalena River basin: Cesar: CIUA 8370 , 8 , 44.9–80.7 mm SL, La Jagua de Ibirico, Tucuy River , 9835 0 13 00 N, 73818 0 34.9 00 W, 122 m a.s.l., V. M. Medina, J. G. Ospina, and D. Restrepo, 9 September 2023 ; CIUA 8371 , 1, 52.1 mm SL, Badillo, Badillo River , 10836 0 12 00 N, 7388 0 4 00 W, 195 m a.s.l., V. M. Medina, J. G. Ospina, and D. Restrepo, 9 September 2023 GoogleMaps . Magdalena: CZUT-IC 14919 , 1 , 81.0 mm SL, Aracataca, Aracataca River , 10834 0 18 00 N, 74814 0 18 00 W, 46 m a.s.l., J. G. Albornoz and G. Beltran, 14 October 2015 GoogleMaps ; UARC-IC 1079 , 3 , 44.5–54.5 mm SL, Zona Bananera, Frío River , 10852 0 06 00 N, 74811 0 29 00 W GoogleMaps . Santander: IAvH-P 20904, 1, 74.8 mm SL, Cimitarra, Carare River Basin , 6826 0 23 00 N, 74808 0 04 00 W, 121 m a.s.l., J. G. Albornoz, A. Méndez, and M. Arias, 13 July 2018 GoogleMaps . Ranchería River basin: La Guajira: CZUT-IC 17447 , 2, 82.1–82.4 mm SL, San Juan del Cesar, Manantial Cañaverales , 10845 0 01 00 N, 72850 0 30 00 W, 281 m a.s.l., C. Conde, 2 March 2017 GoogleMaps .

Diagnosis.— Rineloricaria giua is distinguished from most trans-Andean and Central American congeners (except R.

jubata and R. uracantha ) by having four or five rows of median abdominal plates (vs. three in R. atratoensis and R. magdalenae , more than six in R. altipinnis , R. rupestris , and R. sneiderni ). Rineloricaria giua is also distinguished from this group of species (except R. magdalenae ) by having lateral margins of the snout straight (vs. convex in R. altipinnis , R. atratoensis , R. jubata , R. rupestris , R. uracantha , and R. sneiderni ). Rineloricaria giua differs from R. atratoensis , R. jubata and R. rupestris by having four plates along sides of dorsal-fin base (vs. five). Also, R. giua is distinguished from R. atratoensis and R. magdalenae by absence of a paired deep depression between the nostrils and the interorbital region (vs. present) and postorbital notch small and shallow (vs. large and deep). The new species is further distinguished from most of its congeners (except R. atratoensis , R. aurata , R. beni , R. cadeae , R. castroi , R. catamarcensis , R. felipponei , R. lanceolata , R. langei , R. longicauda , R. magdalenae , R. misionera , R. nigricauda , R. pareiacantha , R. parva , R. quadrensis , R. sanga , R. setepovos , R. sneiderni , R. stellata , R. strigilata , R. thrissoceps , R. uracantha , and R. wolfei ) by lacking the mid-dorsal plate series (vs. present in R. aequalicuspis , R. altipinnis , R. anhaguapitan , R. anitae , R. baliola , R. cacerensis , R. cachivera , R. capitonia , R. caracasensis , R. daraha , R. eigenmanni , R. fallax , R. formosa , R. hasemani , R. heteroptera , R. isaaci , R. jaraguensis , R. jubata , R. konopickyi , R. kronei , R. latirostris , R. maacki , R. malabarbai , R. maquinensis , R. melini , R. microlepidogaster , R. morrowi , R. nudipectoris , R. osvaldoi , R. pentamaculata , R. phoxocephala , R. platyura , R. reisi , R. rodriquezae , R. rupestris , R. steindachneri , R. stewarti , R. teffeana , R. tropeira , and R. zaina ). The new species can be separated from R. cadeae , R. castroi , R. catamarcensis , R. langei , R. lima , R. longicauda , R. misionera , R. nigricauda , R. pareiacantha , R. parva , R. quadrensis , R. sanga , R. setepovos , R. stellata , R. strigilata , and R. uracantha by breeding males with dimorphic odontodes on sides of head and on dorsum of pectoral fin (vs. breeding males lacking dimorphic odontodes). Finally, the new species differs from R. aequalicuspis , R. anhaguapitan , R. anitae , R. aurata , R. baliola , R. capitonia , R. isaaci , R. jaraguensis , R. kronei , R. latirostris , R. maacki , R. malabarbai , R. maquinensis , R. microlepidogaster , R. pentamaculata , R. reisi , R. rupestris , and R. tropeira by having a slender post-pectoral naked area (vs. wide).

Description.— Morphometric data in Table 1. Head and body depressed. Dorsal profile of head triangular. Snout tip acutely pointed in dorsal view and straight (not raised) in lateral view ( Fig. 1B View FIG ). Naked area of snout tip transversally elliptical, not reaching first pore of infraorbital sensory canal. Dorsal profile convex from tip of snout to dorsal-fin origin, and straight to caudal-fin origin. Ventral profile straight from tip of snout to caudal-fin origin. Greatest body depth at posterior border of parieto-supraoccipital; lowest body depth along caudal peduncle ( Fig. 4 View FIG ).

Hypertrophied odontodes of head small to moderate size, forming conspicuous ridges between nostrils, on posterior nasal plates to posterior margin of parieto-supraoccipital and compound pterotic. Five plates in infraorbital series, with sensory pores exposed ventrally. Predorsal plates and first three lateral plates of dorsal series slightly keeled, covered with small odontodes. Eye elliptical with small and shallow postorbital notch, slightly shorter than half of horizontal diameter of orbit ( Fig. 1B View FIG ).

Upper lip short and separated from naked area of snout by thin row of plates covered by tiny odontodes. Margin of upper lip with long, rugged, and regular papillae. Anteroventral border of upper lip separated from anterior border of premaxillary ramus by one row of papillae. Lower lip covered by irregular sized papillae, unorganized and distributed around oral cavity. Edge of lower lip with elongated, triangular fringes. Maxillary barbel long, with minute papillae. Teeth bicuspid and cusps rounded or slightly pointed; dentary teeth larger than premaxillary teeth. Premaxilla with 7(3), 8(6), or 9(2)* teeth; dentary with 8(9)* or 9(2) teeth; accessory cusp almost of same size as main one.

Color in alcohol.— Background coloration of dorsal surface light brown. Pores of sensory system on head and lateral medial plates dark. Dorsal surface of body with five or six dark brown transverse bars; first at dorsal-fin origin, second at level of tip of adpressed dorsal fin, following posterior bars on caudal peduncle. All fins covered by dark spots on fin rays. Ventral surface pale yellow ( Fig. 4 View FIG ). Coloration in life similar to that in preserved specimens ( Fig. 5B View FIG ).

Distribution.— Rineloricaria giua is currently known from the Aracataca River in the lower section of the Magdalena River basin, from the Carare River in the middle section of the Magdalena River, and from the arroyo Manantiales, a tributary of the Caribbean Ranchería River ( Fig. 3 View FIG ).

Sexual dimorphism.— Adult males with hypertrophied odontodes on sides of head and on dorsum of pectoral fin ( Fig. 4 View FIG ), absent in females of similar size ( Fig. 5A View FIG ).

Etymology.— In honor of the Grupo de Ictiología of Universidad de Antioquia (acronym GIUA). Used as a noun in apposition.

Remarks.— Rineloricaria giua is widely distributed across the middle and lower sections of the Magdalena River, being sympatric and even syntopic with R. magdalenae . However, scarce records of the new species in ichthyological collections in Colombia suggest that populations of R. giua are less abundant when compared to the ubiquitous specimens of R. magdalenae .

Morphometric analysis.— The PCA analysis shows broad overlap of all species, with the first two axes accounting for 41.2% of the variance between groups ( Fig. 6A View FIG ). In turn, LDA analysis shows a clear separation of specimens corresponding to Rineloricaria giua ( Fig. 6B View FIG ), indicating that morphometric variables used in this study allow morphometric recognition of this species. Contrarily, R. atratoensis overlaps with R. magdalenae .

The first two LDA axes explain 79.7% of the variance ( Fig. 6B View FIG ), and the overall precision of the classification in the correct group was 75.3%. Variables with higher scores on the positive LD1 axis were postanal length, orbital diameter with notch, and abdominal length, while those on the negative side were mouth length, pectoral-spine length, and interorbital width. Higher positive scores for LD2 were accounted by abdominal length, interorbital width, and orbital diameter with notch; and for the negative axis, postanal length, dorsal-spine length, dorsal-fin base length, and internare width.

found to be different from R. magdalenae in morphometric analyses (see above), was recovered as sister to a clade comprising R. altipinnis , R. jubata , R. rupestris , and R. uracantha (node support: 72%).

Genetic distances.— Distribution of paired genetic distances of sequences from the trans-Andean species in our analysis shows a variation range between 3.1% and 15.9%. The minimum interspecific genetic distance value found for R. atratoensis and R. magdalenae was 3.1%, while the maximum scores recorded between R. atratoensis and remaining species were 14.1–15.9%. For R. giua , genetic distances varied from 10.3% to 15.1% ( Table 2).

Delimitation analyses.— Both ASAP and PTP analysis yielded the same 11 putative species, eight of them from the trans-Andean region ( Fig. 7 View FIG ). In the ASAP analysis, the second partition was selected, since it agrees with our morphology-based species delimitation (score ¼ 5.00). In the PTP analysis, support values for trans-Andean species were below 50%, except for Rineloricaria giua , which was 86.7% ( Fig. 7 View FIG ).