Rineloricaria rodriquezae, Costa-Silva & Oliveira & Costa, 2021

Costa-Silva, Guilherme José Da, Oliveira, Claudio & Costa, Gabriel De Souza Da, 2021, New species of Rineloricaria (Siluriformes: Loricariidae) from the Paranaíba River basin, Brazil, Zootaxa 5072 (6), pp. 531-540 : 532-537

Rineloricaria rodriquezae , new species

Fig. 1 . Table.1 .

Rineloricaria sp. 8 — Costa-Silva et al. (2015) [molecular delimitation]

Holotype. MZUSP 125901 , 127.2 mm SL, Minas Gerais state, Rio Paranaíba municipality, Paranaíba River, Upper Paraná River basin, S 19°11’32.00” W46°24’44.90”, 17 Oct 20201, G.J. Costa-Silva, G.S.Costa e Silva

Paratypes. All from Brazil, Minas Gerais state, Rio Paranaíba municipality, Paranaíba River basin: LBP 11721, 7, 40.2–140.5 mm SL, same data as holotype. LBP 11741, 7, 51.5–108.5 mm SL, Ribeirão de Fora , S 19°11’32’’ W 46°24’44’’, 18 May 2011, R. Britske, G.J. Costa-Silva, R. Devidé, C. Oliveira. Non-type. LBP 30680, 5, 76.3–98.3 mm SL, Federal District, Brasília, Ribeirão Santana, Paranaíba River basin, S 16° 0’53.53” W 47°48’3.45” GSC Silva & L Reia

Diagnosis. Rineloricaria rodriquezae differs from all congeners, except R. anhaguapitan , R. anitae , R. baliola , R. capitonia , R. tropeira and R. zaina by the presence of a dark bar on the subterminal region of the caudal fin (vs. absence of a dark bar on subterminal region of the caudal fin; Fig. 1 ), but R. rodriquezae presents an extension of the upper unbranched caudal fin ray extended on filament, while R. anhaguapitan , R. anitae , R. baliola , R. capitonia , R. tropeira and R. zaina do not present this extension. Additionally, the new species differs from its congeners by having five series of lateral plates in longitudinal rows below the dorsal fin (vs. four series of lateral plates in longitudinal rows below the dorsal fin in R. microlepidota , R. aurata , R. beni , R. cadeae , R. castroi , R. catamarcensis , R. cubatonis , R. felipponei , R. henselli , R. jurupari , R. lanceolata , R. langei , R. lima , R. longicauda , R. magdalenae , R. misionera , R. nigricauda , R. pareiacantha , R. parva , R. quadrensis , R. sanga , R. setepovos , R. sneiderni , R. stellate , R. thrissoceps , R. uracantha , and R. wolfei ); by having the lateral plate of the mid-dorsal series consisting of two keeled plates situated around the insertion of the first ray of the dorsal fin (vs. lateral plate of the mid-dorsal series consisting in five to seven keeled plates extended posteriorly around end of the dorsal-fin base in R. cacerensis , R. daraha , R. fallax , R. formosa , R. hasemani , R. jubata , R. melini , R. microlepidogaster , R. morrowi , R. osvaldoi , R. teffeana , and R. zaina ) (see more in Vera-Alcaraz et al. 2012); by the presence of the dorsal unbranched caudal-fin ray extended as long filaments (vs. dorsal unbranched caudal-fin ray not extended as long filaments in R. aequalicuspis , R. anhaguapitan , R. anitae , R. baliola , R. capitonia , R. heteropteran , R. isaaci , R. jaraguensis , R. maacki , R. malabarbai , R. maquinensis , R. microlepidota , R. pentamaculata , R. reisi , R. rupestris , R. tropeira and R. zaina ); and by absence of hypertrophied odontoides on the predorsal region in mature males (vs. presence of hypertrophied odontodes in R. altipinnis , R. caracasensis , R. eigenmanni , R. konopickyi , R. phoxocephala , R. platyura , and R. stewarti ).

Description. Morphometric and meristic data are summarized in Table 1 . Small-sized loricariid (maximum 140.5 mm SL). Head and snout triangular in dorsal view. Dorsal profile of head ascending convexly approximately 45° to eyes. Eyes relatively large (12.9–11.9% of HL), dorsolaterally positioned, elliptical with large, deep postorbital notch. Iris operculum present and well developed. Oral disk rounded with papillae randomly distributed. Lower lip larger than upper lip, not reaching cleithrum; border with elongated fringes; lower lip inner surface covered with irregular-sized papillae arranged concentrically around oral cavity. Maxillary barbel short covered by small papillae. Teeth slender with two cusps; central cusp larger than lateral cusp. Premaxillary teeth 5–6 (mode 6). Dentary teeth 5–8 (mode 8). Snout very short, elliptical. Snout naked area not reaching most anterior pore of infraorbital ramus of sensory canal.

Lower surface of head naked. Head lacking ridges. Predorsal region keeled with small odontoids covering plates. In dorsal view, body elongated and compressed. Greatest body width at pectoral-fin insertion, progressively narrowing anteriorly towards snout tip and posteriorly towards caudal-fin. Dorsal profile of head and trunk covered by dermal plates, except for naked area around dorsal-fin insertion. In lateral view, body depressed and convex in shape from snout tip to dorsal-fin origin; slightly concave and descending from dorsal-fin origin to first upper procurrent caudal-fin ray, rising posteriorly to insertion of caudal fin. Greatest body depth at unbranched dorsal-fin ray insertion.

In lateral view, ventral profile straight and descending from snout tip to opercular region; slightly convex from opercular region to pelvic-fin origin; straight from that point to lower procurrent caudal-fin ray origin. Lateral surface of body entirely covered by plates, median and mid-ventral series with keels; dorsal series with 23–25 plates. Mid-dorsal plate series truncated 1–3. Median series with 26–27 plates. Lateral line complete. Mid-ventral series with 14–16. Ventral plates series with 20–21 plates. Abdomen entirely covered by plates, from cleithrum to urogenital papilla. Lateral abdominal plates larger and forming regular series of nine to ten elongate plates on each side; median abdominal plates smaller, irregularly arranged, anteriorly consisting of small, rounded plates on pectoral girdle region, posteriorly consisting of larger and trapezoidal plates.

Dorsal fin ii,7; its origin slightly posterior through pelvic-fin origin. Dorsal-fin unbranched ray slightly convex. Tip of adpressed dorsal-fin rays surpassing anal-fin origin. Pectoral-fin rays i,6; when adpressed its tip passing adpressed pelvic-fin ray insertion reaching. Pelvic-fin rays i,5; its distal margin straight to slightly convex; tip of adpressed pelvic-fin ray reaching anal-fin origin. Adipose fin absent. Anal-fin rays i,5; distal margin slightly convex. Caudal-fin rays i,10, i; truncate, with short, thin filament on dorsal caudal-fin ray.

Color in alcohol. Background color of the dorsal region of head and trunk red to brown ( Fig 1 ; 2 ). Five (six in one specimen: LBP 11741, SL 89.7) dark transversal bars along the dorsal surface of body: first at dorsal-fin origin, second at end of dorsal-fin base, following bands equidistant to each other. Chromatophores widely concentrated on compound-pterotic and on posterior two predorsal plates forming dark brown conspicuous area. Anterior margin of head with irregular reddish dots. Ventral surface of body yellowish. Dorsal, pectoral, and pelvic fins with irregular dark brown stripes, distal region with reddish band. Caudal fin hyaline with a vertical subterminal dark bar and with a small dark brown spot on its base; caudal-fin middle region with irregular dark-brown stripes; on distal portion large, vertical dark-brown band ( Fig.1 ; 2 ).

Sexual dimorphism. Adult males with hypertrophied odontodes on lateral margin of head extending from postrostral plate to opercle and in pectoral-fin rays.

Distribution. Rineloricaria rodriquezae is known from Ribeirão de Fora and a small stream reaching the Paranaíba River both tributaries of the Paranaíba River, in the Upper Paraná River basin, centralBrazil. ( Fig. 3 ).

Habitat. Rineloricaria rodriquezae was collected in small drainages with moderate water flow and average deep of 60 cm ( Fig. 4 ). The riparian forest is preserved, and the canopy covers almost the entire bed. The rivers where the specimens were sampled do not cross urban perimeters, and no signs of severe environmental degradation were detected. The type locality where the new species was caught, is a stream river with sand botton and gravel. Smaller individuals were collected from small roots of riparian vegetation and submerged trunks and branches, while the larger individuals, including the holotype, were always collected from submerged trunks and branches.

Remarks. The new species is known from the Rio Paranaíba (type locality) in Minas Gerais state and Ribeirão Santana in Distrito Federal. The population of Rineloricaria rodriquezae sampled in Ribeirão Santana presents the eyes diameter significantly bigger than the population of the type locality 15.6–17.5% in HL (vs. 10.3–12.9% in HL; see table 1). For this reason, although it shares the diagnosis of R. rodriquezae , we find it more convenient that the population of Ribeirão Santana not to be included in the type series. We propose that an integrative taxonomy be carried out to assess whether even more species are distributed in the upper Paraná River basin.

Etymology. The specific name rodriquezae honors Mónica Sonia Rodriguez in recognition for her contribution on the knowledge to the genus Rineloricaria .

Figures

FIGURE 1. Rineloricaria rodriquezae, holotype, MZUSP 125901, 127.2 mm SL, male (?) specimen from Paranaíba River (Upper Paraná River basin), municipality of Rio Paranaíba, Minas Gerais state, Brazil.

FIGURE 2. Body-color pattern difference between Rineloricaria rodriquezae and Rineloicaria latirostris. A) R. rodriquezae, male paratype, LBP 30720. 92.0 mm SL. B) R. latirostris, male topotype LBP 30721. 87.5 mm SL.

FIGURE 3. Distribution of Rineloricaria latirostris group with genetic distance values: White star is the type locality of Rineloricaria rodriquezae.Yellow star andyellow diamond arenon-type localities of Rineloricariarodriquezae and Rineloricaria latirostris respectively. The values found in the branches of the tree correspond to the genetic distances observed in Costa Silva et al. (2015).

FIGURE 4. Habitat of Rineloricaria rodriquezae, a stream of the Ribeirão de Fora, tributary of the Paranaíba River.