A new species of Loricaria (Siluriformes: Loricariidae) from the Turiaçu River basin, Eastern Amazon region, Brazil Saraiva, Ananda Carolina S. Abreu, João Marcelo S. Ottoni, Felipe Polivanov Piorski, Nivaldo Magalhães Zootaxa 2021 2021-01-22 4915 3 424 434 Saraiva & Abreu & Ottoni & Piorski, 2021 Saraiva & Abreu & Ottoni & Piorski 2021 [151,317,1807,1833] Actinopterygii Loricariidae Loricaria Animalia Siluriformes 1 425 Chordata species turi sp. nov.   Figure 1, Table 1.     Holotype: CPUFMA 3204, 192.2 mmSL, Lago do Rapa Cuia, Turiaçu Riverbasin, Maranh„o, Brazil, 2° 23’ 30.28” S 45° 23’ 49.15” W,  16 to 21 October 2000, N. M. Piorski.    Paratypes: Allfrom Brazil. CPUFMA 196, 4, 178.4– 186.4 mmSL, Lago Mendes, Turiaçu Riverbasin, N. M. Piorski. CICCAA 04212, 3, 174.6–183.0 mm SL, municipality of Santa Helena, Lago do Arrodeador, Turiaçu Riverbasin, 2° 16’ 35.04” S, 45° 22’ 19.28” W, N. M. Piorski& L. Pereira. MCP54091, 4, 183.7– 197.7 mmSL, municipality of Santa Helena, Lagode S„o Pedro, Turiaçu Riverbasin, 2° 43’ 4.6” S, 45° 27’ 29.35” W, N. M. Piorski. CPUFMA 285, 1, 214.8 mmSL,  Lago do Rapa Cuia, Turiaçu Riverbasin, N. M. Piorski.   FIGURE 1.  Loricaria turi, holotype, CPUFMA 3204, 192.2 mm SL, Lago do Rapa Cuia, Turiaçu River Basin, municipality of Santa Helena, Maranh„o state, Brazil.  Non–type specimens:All from Turiaçu River basin, Maranh„o, Brazil. CPUFMA 221, 12, 159.2– 203.3 mmSL, Lago Mendes, N. M. Piorski. CPUFMA 340, 3, 153.0– 156.8 mmSL, Lago do Quebra–Pote, N. M. Piorski & L. Pereira. CPUFMA 344, 3, 152.6– 174.9 mmSL, Lago do Quebra–Pote, N. M. Piorski & L. Pereira. CPUFMA 345, 26, 164.6– 186.9 mmSL, Lago do Quebra-Pote, N. M. Piorski & L. Pereira. CPUFMA 351, 20, 157.6– 200.4 mmSL, Lago do Arrodeador, N. M. Piorski & L. Pereira. CPUFMA 417, 15, 161.9– 195.7 mmSL. CPUFMA 196, 4, 176.3– 186.4 mmSL, Lago Mendes, N. M. Piorski. CPUFMA 197, 9, 176.7– 209.2 mmSL, Lago de S„o Pedro, N. M. Piorski. CPUFMA 226, 3, 174.2– 195.8 mmSL, Lago de S„o Pedro, N. M. Piorski. CPUFMA 261, 2, 193.3– 204.8 mmSL, Lago de Fora, N. M. Piorski. CPUFMA 470, 10, 183.7– 197.9 mmSL, Lago de S„o Pedro, N. M. Piorski. CPUFMA 471, 14, 171.6– 188.1 mmSL, Lago Mendes, N. M. Piorski. CPUFMA 502, 7, 157.0– 201.8 mmSL, Lago de S„o Pedro, N. M. Piorski.   Diagnosis.  Loricaria turidiffers from all its congeners, except  L. holmbergi, L. parnahybae, L. spinulifera, L. pumila, L. luciae, L. coximensisand  L. lundbergiby having abdominal plate development confined to the posterior median region, pectoral girdle mostly naked, with isolated plates near pectoral fin base ( vsabdominal plates typically well developed and tightly arranged across the entirely median abdominal area, including the pectoral girdle or abdominal plates small and granular covering all median abdominal area and pectoral girdle) ( Figure 2). The new species differs from  L. holmbergiby having a larger basicaudal plate (16.6–29.2% vs9.0–14.2% of HL), and a larger minimum orbital diameter (16.2–20.6% vs13.3–16.1% of HL); from  L. parnahybaeby having a larger basicaudal plate (27.8–40.4% vs18.9–26.5% of SGD), standard length reaching up to 214 mm( vsstandard length reaching 174.4 mm), and higher number of buccal papillae (14–16 vs8–12); from  L. spinuliferaand  L. pumilaby absence of strongly developed crests on surface of head ( vspresence of strongly developed crests on surface of head, see Thomas & Rapp Py-Daniel 2008: fig. 3a,c); the new species is further distinguished from  L. spinuliferaby presence of preanal shield ( vsabsence of preanal shield, see Thomas & Rapp Py-Daniel 2008: fig. 4b); from  L. pumilaby having a smaller interorbital distance (15.3%–19.5% vs21.0–27.2% of HL), higher number of post-anal plates (19–21, modally 20 vs18–19, modally 18), higher number of total lateral plates (32–34, modally 34 vs31–32, modally 31), and having standard length up to 214.0 mm ( vsstandard length not surpassing 81.0 mm); from  L. luciaeby having a smaller post-dorsal distance (52.1–56.7% vs58.5–62.3% of SL), smaller post-anal distance (43.7–49.0% vs50.0–53.9% of SL), and narrower body at anal spine (9.2–11.6% vs12.0–14.4% of SL); from  L. coximensisby narrower head width (13.6–16.6% vs19.4–21.3% of SL), shorter head length (19.1–22.2% vs23.4–26.2% of SL), and higher number of post-anal plates (19–21 vs16–18); and from  L. lundbergiby larger basicaudal plate (16.6–29.2% vs9.0–11.9% of HL), narrower head width (13.6–16.6% vs17.6–18.4% of SL), and smaller post-anal distance (43.8–49.0% vs51.6–55.1% of SL).   Description: Morphometric and meristic data are presented in Table 1. Body elongated, slender and depressed dorsoventrally. Peduncle caudal elongated and depressed, body widest at cleithrum (12.3–15.0% of SL). Dorsal profile of head, from tip of snout to posterior tip of parieto-supraoccipital, slightly convex and from parieto-supraoccipital to origin of dorsal fin straight to slightly convex. In dorsal view, head triangular shaped with straight to slightly convex margins from tip of snout to operculum; tip of snout rounded. Lateral view of body from dorsal-fin insertion to end of caudal peduncle slightly concave. Greatest body depth at dorsal-fin origin (7.7–11.1% SL). Eyes large, minimum orbital diameter 16.2–20.6% HL; post-orbital notch present and rounded, maximum orbital diameter 19.3–24.1% HL. Body totally covered by dermal plates, except on ventral surface of head, under lower lip, pectoral girdle region, around base of pelvic fin and V-shaped area around anus. Dermal plates on head and predorsal plates with poorly to moderately developed odontodes keels. In ventral view, abdomen covered irregularly with plates. Middle portion with small plates disposed anteriorly and larger plates disposed posteriorly. Odontodes poorly developed on margin of orbits. Posterior portion of supraoccipital with two separated odontode keels closely parallel to each other, extending to predorsal plates. Nuchal plate with median crest present.   TABLE 1.Morphometrics and meristics data of  Loricaria turi(N= 143). SD= Standard Deviation.      Loricaria turi   Percent of SL  Holotype  Range  Mean  SD  Standard length (mm) 192.2 152.3–214.7 178.9 10.8  Head length 20.3 19.1–22.2 20.3 0.6  Predorsal length 29.4 27.0–31.6 29.3 0.7  Body depth 8.5 7.7–11.0 9.3 0.6  Post–dorsal length 56.7 52.1–56.7 54.5 1.0  Post-anal length 49.0 43.8–49.0 46.3 1.1  Head width 14.8 13.6–16.6 14.7 0.5  Body width at post–cleithral tip 13.5 12.3–15.0 13.6 0.5  Body width at dorsal fin spine 11.6 11.1–14.0 12.6 0.6  Body width at anal fin spine 11.1 9.2–11.6 10.3 0.5  Abdominal length 14.0 11.6–14.8 13.1 0.6  Thoracic length 14.2 12.3–15.7 14.1 0.7  Dorsal spine length 21.3 17.3–26.3 22.6 2.0  Pectoral spine length 18.7 16.6–22.0 18.5 1.0  Pelvic spine length 18.0 15.5–19.8 17.9 1.0  Anal spine length 14.5 12.3–19.6 16.7 1.4   Percent of HL  Snout length 51.7 49.8–56.6 53.0 1.2  Minimum orbital diameter 19.0 16.2–20.7 18.6 0.8  Maximum orbital diameter 22.9 19.8–24.0 22.2 0.9  Head depth 39.0 36.0–44.7 40.3 1.6  Caudal penducle least depth 5.9 5.2–7.7 6.0 0.3  Internares distance 7.7 7.7–12.5 9.8 0.9  Nares to orbit distance 19.1 18.0–23.8 20.8 1.1  Snout to operculum 75.8 72.3–77.4 74.5 1.2  Interorbital distance 17.5 15.3–19.5 17.6 0.9  Orbit to supraoccipital tip distance 40.6 37.0–43.0 40.3 1.2  Basicaudal plate length 16.6 16.6–29.2 23.1 2.3   Meristics  Holotype  Range  Mode  Anterior lateral plates 18 17–20 19  Posterior lateral plates 15 13–17 15  Lateral total plates 33 32–34 34  Post-anal plates 20 19–21 20  Premaxillary teeth 3 3–4 3  Dentary teeth 7 7–9 7 Upper lip with numerous marginal fringe barbels, without secondary branches. Lower lip with numerous, long, fringe barbels without secondary branches; filiform papillae covering both lobes of lower lip. Maxillary barbel relatively long and simple usually not extending beyond marginal fringe barbel of lower lip. Premaxillary teeth biscupid 3–4 (modally 3) per side; base of each tooth thin and elongate, until forming bicuspid tip. Medial and lateral lobes of teeth conical or rounded; inner lobe larger and wider than outer lobe. Buccal papillae, behind upper jaw, varies from 14 to 16. Dentary teeth 6–9 (modally 7) per ramus, smaller than premaxillary teeth (reaching about half of the size), and structurally similar. Dorsal-fin, when adpressed, usually reaching 10 thor 11 thlateral plates, posterior to cleithrum; dorsal spine and first branched ray equal in length. Adpressed pectoral-fin reaches seventh lateral plate, posterior to cleithrum; pectoral spine and first branched ray with same length, other rays shorter. Pelvic-fin spine reaching fourth lateral plate from anal-fin origin. Anal-fin spine reaching seventh or eighth lateral plate posterior to its origin; all branched and unbranched rays equal in length. Basicaudal plate large (16.6–29.2% of HL).  Color in alcohol:Dorsal surface light brown to yellow, uniform. Most specimens faded with body and fins without contrasting pigmentation patterns. No visible spots or blotches on spine or branched rays. Ventral surface light yellow. Dorsal, pectoral, and anal fin spine light brown and distal margin of branched rays hyaline. Ventral fin spine yellow, distal margin reddish, and branched rays hyaline.  Sexual dimorphism: Fifty-nine specimens larger than 152.0 mm of SL showed the same characteristics of sexual dimorphism observed in sexually mature males of other species of  Loricaria: shorter filiform papillae in lower lip and increase in number of globular papillae. Pectoral spine slightly thickened, club-shaped. Teeth with round cusps, both in premaxillary and dentary.   Distribution:  Loricaria turiis known only from the Turiaçu River basin, a river basin located in the Eastern Amazon region in the Maranh„o state, Brazil( Figure 3).   FIGURE 3.Geographic distribution of  Loricaria turi. Star represents the holotype and circles paratypes.  Habitat:Lago do Rapa-Cuia, the typelocality, is a small lake that is connected to the main channel of the Turiaçu River only during the rainy season. The maximum depth varies between 2 and 3 meters, with a sandy bottom, and surrounded by Igapo forest. This is one of the lakes used by Fishermen to camp together with families during the dry season (Piorski, pers. obs.).   Variation:Among all the specimens of  Loricaria turianalyzed, the pattern of abdominal coverage is quite consistent. However, some specimens of  L. turismaller than 150 mmSL presented variation in the abdominal coverage. In these specimens, median abdominal area with small polygonal plates loosely dispersed and naked pectoral girdle. In specimens greater than 150 mmSL, median abdominal area with large polygonal plates tightly joined on pre-anal shield and posterior median abdominal space, anterior median abdominal area with smaller polygonal plates.   Etymology: The specific epithet “  turi” refers to the Turiaçu basin and the way in which the native people call the river: “Rio Turi”.  Linear regressions:In the MHU region,  Loricaria cataphractais the congener of  L. turi(see Piorski et al.1998, 2007). Because  L. cataphractais presumed to be from Suriname, samples of it will be named  Loricariacf. cataphractain this paper. The linear regressions used demonstrated some slight differences between  L. turiand  L.cf. cataphracta .The new species has a larger minimum orbital diameter, smaller post-anal distance, smaller postdorsal distance, and smaller internares distance than  L.cf. cataphracta( Figure 4). 3028580304 2000-10-16 2000-10-21 2000-10-16 N. M. Piorski. Brazil Maranh -2.3917444 Lago do Rapa Cuia 1 -45.396988 Turiacu River 1 425 1 holotype 3028580303 MCP 54091 MCP N. M. Piorski Brazil Turiacu River 2 426 -2.7179444 All 1 -45.458153 Lago do Rapa Cuia 1 425 CPUFMA 196, 4, 178.4, CICCAA 04212, 3, 174.6, 183.7, CPUFMA 285 1 paratype 3028580302 MCP 54091 MCP N. M. Piorski & L. Pereira. Brazil Turiacu River -2.7179444 All 1 -45.458153 Lago do Rapa Cuia 2 426 CPUFMA 196, 4, 178.4, CICCAA 04212, 3, 174.6, 183.7, CPUFMA 285 1 paratype 3028580301 MCP 54091 MCP N. M. Piorski Brazil Turiacu River -2.7179444 All 1 -45.458153 Lago do Rapa Cuia 2 426 CPUFMA 196, 4, 178.4, CICCAA 04212, 3, 174.6, 183.7, CPUFMA 285 1 paratype 3028580305 MCP 54091 [523,1145,259,285] MCP N. M. Piorski Brazil Turiacu River -2.7179444 All 1 -45.458153 Lago do Rapa Cuia 2 426 CPUFMA 196, 4, 178.4, CICCAA 04212, 3, 174.6, 183.7, CPUFMA 285 1 paratype