Loricaria turi, Saraiva & Abreu & Ottoni & Piorski, 2021

Saraiva, Ananda Carolina S., Abreu, João Marcelo S., Ottoni, Felipe Polivanov & Piorski, Nivaldo Magalhães, 2021, A new species of Loricaria (Siluriformes: Loricariidae) from the Turiaçu River basin, Eastern Amazon region, Brazil, Zootaxa 4915 (3), pp. 424-434 : 425-430

Loricaria turi new species

Figure 1 , Table 1.

Holotype: CPUFMA 3204, 192.2 mm SL, Lago do Rapa Cuia , Turiaçu River basin, Maranh „o, Brazil, 2° 23’ 30.28” S 45° 23’ 49.15” W, 16 to 21 October 2000, N. M. Piorski.

Paratypes: All from Brazil. CPUFMA 196 , 4 , 178.4 – 186.4 mm SL, Lago Mendes , Turiaçu River basin, N. M. Piorski. CICCAA 04212 , 3 , 174.6 –183.0 mm SL, municipality of Santa Helena, Lago do Arrodeador , Turiaçu River basin, 2° 16’ 35.04” S, 45° 22’ 19.28” W, N. M. Piorski & L. Pereira. MCP 54091, 4 , 183.7 – 197.7 mm SL, municipality of Santa Helena, Lago de S„o Pedro , Turiaçu River basin, 2° 43’ 4.6” S, 45° 27’ 29.35” W, N. M. Piorski. CPUFMA 285 , 1, 214.8 mm SL, Lago do Rapa Cuia, Turiaçu River basin, N. M. Piorski .

Non–type specimens: All from Turiaçu River basin, Maranh„o, Brazil. CPUFMA 221, 12, 159.2– 203.3 mm SL, Lago Mendes, N. M. Piorski. CPUFMA 340, 3, 153.0– 156.8 mm SL, Lago do Quebra–Pote, N. M. Piorski & L. Pereira. CPUFMA 344, 3, 152.6– 174.9 mm SL, Lago do Quebra–Pote, N. M. Piorski & L. Pereira. CPUFMA 345, 26, 164.6– 186.9 mm SL, Lago do Quebra-Pote, N. M. Piorski & L. Pereira. CPUFMA 351, 20, 157.6– 200.4 mm SL, Lago do Arrodeador, N. M. Piorski & L. Pereira. CPUFMA 417, 15, 161.9– 195.7 mm SL. CPUFMA 196, 4, 176.3– 186.4 mm SL, Lago Mendes, N. M. Piorski. CPUFMA 197, 9, 176.7– 209.2 mm SL, Lago de S„o Pedro, N. M. Piorski. CPUFMA 226, 3, 174.2– 195.8 mm SL, Lago de S„o Pedro, N. M. Piorski. CPUFMA 261, 2, 193.3– 204.8 mm SL, Lago de Fora, N. M. Piorski. CPUFMA 470, 10, 183.7– 197.9 mm SL, Lago de S„o Pedro, N. M. Piorski. CPUFMA 471, 14, 171.6– 188.1 mm SL, Lago Mendes, N. M. Piorski. CPUFMA 502, 7, 157.0– 201.8 mm SL, Lago de S„o Pedro, N. M. Piorski.

Diagnosis. Loricaria turi differs from all its congeners, except L. holmbergi , L. parnahybae , L. spinulifera , L. pumila , L. luciae , L. coximensis and L. lundbergi by having abdominal plate development confined to the posterior median region, pectoral girdle mostly naked, with isolated plates near pectoral fin base (vs abdominal 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. holmbergi by having a larger basicaudal plate (16.6–29.2% vs 9.0–14.2% of HL), and a larger minimum orbital diameter (16.2–20.6% vs 13.3–16.1% of HL); from L. parnahybae by having a larger basicaudal plate (27.8–40.4% vs 18.9–26.5% of SGD), standard length reaching up to 214 mm (vs standard length reaching 174.4 mm), and higher number of buccal papillae (14–16 vs 8–12); from L. spinulifera and L. pumila by absence of strongly developed crests on surface of head (vs presence 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. spinulifera by presence of preanal shield (vs absence of preanal shield, see Thomas & Rapp Py-Daniel 2008: fig. 4b); from L. pumila by having a smaller interorbital distance (15.3%–19.5% vs 21.0–27.2% of HL), higher number of post-anal plates (19–21, modally 20 vs 18–19, modally 18), higher number of total lateral plates (32–34, modally 34 vs 31–32, modally 31), and having standard length up to 214.0 mm (vs standard length not surpassing 81.0 mm); from L. luciae by having a smaller post-dorsal distance (52.1–56.7% vs 58.5–62.3% of SL), smaller post-anal distance (43.7–49.0% vs 50.0–53.9% of SL), and narrower body at anal spine (9.2–11.6% vs 12.0–14.4% of SL); from L. coximensis by narrower head width (13.6–16.6% vs 19.4–21.3% of SL), shorter head length (19.1–22.2% vs 23.4–26.2% of SL), and higher number of post-anal plates (19–21 vs 16–18); and from L. lundbergi by larger basicaudal plate (16.6–29.2% vs 9.0–11.9% of HL), narrower head width (13.6–16.6% vs 17.6–18.4% of SL), and smaller post-anal distance (43.8–49.0% vs 51.6–55.1% 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.

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 th or 11 th lateral 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 turi is known only from the Turiaçu River basin, a river basin located in the Eastern Amazon region in the Maranh„o state, Brazil ( Figure 3 ).

Habitat: Lago do Rapa-Cuia, the type locality, 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 turi analyzed, the pattern of abdominal coverage is quite consistent. However, some specimens of L. turi smaller than 150 mm SL 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 mm SL, 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 cataphracta is the congener of L. turi (see Piorski et al. 1998, 2007). Because L. cataphracta is presumed to be from Suriname, samples of it will be named Loricaria cf. cataphracta in this paper. The linear regressions used demonstrated some slight differences between L. turi and 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 ).

Figures

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.

FIGURE 2. Abdominal plate variation between: A) Loricaria parnahybae (CPUFMA 159, 167.4 mm SL); B) Loricaria cf. cataphracta (CPUFMA 2150, 205.6 mm SL); C) Loricaria turi (CPUFMA 285, 214.8 mm SL).

FIGURE 3. Geographic distribution of Loricaria turi. Star represents the holotype and circles paratypes.

FIGURE 4. Linear regressions of morphometric variables in L. cf. cataphracta and L. turi. All measurements are expressed in millimeter. A) Head length vs Minimum orbital diameter (L. cf. cataphracta: R2=0.33, p<0.0001; L. turi: R2=0.54, p<0.0001); B) Head length vs Internares distance(L. cf. cataphracta: R2=0.37, p<0.0001; L. turi: R2=0.65, p<0.0001); C) Standard length vs Post–dorsal distance (L. cf. cataphracta: R2=0.85, p<0.0001; L. turi: R2=0.97, p<0.0001); D) Standard length vs Post-anal distance (L. cf. cataphracta: R2=0.83, p<0.0001; L. turi: R2=0.95, p<0.0001).