Loricaria lundbergi, Thomas & Rapp Py-Daniel, 2008

Thomas, Matthew R. & Rapp Py-Daniel, Lúcia H., 2008, Three new species of the armored catfish genus Loricaria (Siluriformes: Loricariidae) from river channels of the Amazon basin, Neotropical Ichthyology 6 (3), pp. 379-394 : 389-392

Loricaria lundbergi , new species

Figs. 8 and 4c

Holotype. INPA 28854 [ex. ANSP 178694] (1, 103.6 mm SL), Brazil , Amazonas , rio Negro (Amazonas dr.), 4.3 km downstream of Carvoeiro, 37.0 km upstream of Moura (01º20’26.4”S, 61º55’19.0”W), 9 Dec 1993, J. G. Lundberg et al .

Paratypes (6). Brazil: Amazonas: ANSP 178694 (1 c&s, 76.8 mm SL), same data as holotype ; INPA 28855 [ex. ANSP 178694] (2, 76.6-80.4 mm SL) same data as holotype ; ANSP 187412 (2, 84.2- 92.4 mm SL), rio Negro (Amazonas dr.), 13.0 km downstream from Carvoeiro , 38.9 km upstream from Moura (01º20’49.2”S, 61º54’56.6”W ), 9 Dec 1993, J. P. Friel et al. Venezuela: Território Federal Amazonas, Dept. Rio Negro: AMNH 74474 (1, 138.1 mm SL) rio Mawarinuma (Baria-Negro dr.), at Neblina base camp (0º55’N, 66º10’W), 6 to 13 Feb 1984, C. J. Ferraris, G. J. Nelson, R. Royero.

Diagnosis. Loricaria lundbergi exhibits the generalized morphology shared with other members of the L. cataphracta group, particularly L. cataphracta , L. clavipinna , L. lata , L. parnahybae , L. simillima , and L. tucumanensis . With the exception of L. parnahybae , L. lundbergi is distinguished from these and other congeners by having abdominal plate development confined to the pre-anal shield and posterior median abdominal area, pectoral girdle mostly naked, and with isolated clusters of plates near bases of pectoral fins posterior to gill openings often present in adults ( Fig. 4c ), vs. abdominal plates typically well developed and tightly arranged across the entire median abdominal area, including the pectoral girdle ( Fig. 4d ). Loricaria lundbergi differs from L. parnahybae , a species restricted to the rio Parnaíba drainage in northeastern Brazil, by having a broader head (17.6-18.4% SL vs. 13.7- 15.8% SL; Fig. 9 ), smaller basicaudal plate (9.0-11.9% vs. 12.9- 15.4% HL; Fig.10 ), body marked with conspicuous dark saddles and fins with solid dark pigment ( Fig. 8 ) vs. body faintly marked with dark saddles and fins with small spots. Loricaria lundbergi is further distinguished from L. simillima , a similar and potentially sympatric species, by having a smaller basicaudal plate (9.0-11.9% vs. 11.7-23.6% HL; Fig.11).

Description. Standard length of specimens examined 76.6- 138.1 mm SL. Other morphometric data presented in Table 1. Meristic data for selected dermal plate characters in Table 2.

Body elongate and slender, dorsoventrally depressed, widest at cleithrum. Head in transverse profile slightly concave between lateral margins and ventral rim of orbit, straight on top of head between orbits; bluntly triangular in frontal profile, lateral margins from snout tip to operculum slightly convex, snout slightly rounded. Dorsal profile of head from snout tip to parieto-supraoccipital tip convex, from parietosupraoccipital tip to dorsal-fin origin slightly concave. Dorsal profile of body from dorsal-fin origin to caudal peduncle slightly concave. Greatest body depth at dorsal-fin origin, 8.1-9.7% SL. Eye moderately large, maximum orbital diameter 17.8-21.2% HL; iris operculum present, although inconspicuous in specimens collected from deep channel habitats of large rivers. Postorbital notch moderately developed and rounded in smaller specimens examined (76.6-103.6 mm SL); well developed and slightly angular in largest specimen examined (138.1 mm SL).

Entire body covered with dermal plates except for ventral surface of head anterior to branchiostegals, anterior median abdominal area, around bases of pelvic fins, and V-shaped area surrounding anus. Dermal plates on dorsum of body from snout tip to dorsal-fin origin with weakly to moderately developed odontode crests. Odontodes moderately developed on lateral margins of head from snout tip to opercle and along anterodorsal margin of orbit. In smaller specimens (76.6- 103.6 mm SL), two prominent odontode crests originating at snout tip converging between nares, becoming divergent on frontals, continuing in parallel to posterior parieto-supraoccipital tip; odontode crests less conspicuous in largest specimen (138.1 mm SL). Dorsal and dorsolateral plates between pterotic-supracleithrum and dorsal-fin origin each with single prominent median crest. Lateral surface of exposed cleithrum with inconspicuous median keel of odontodes.

Upper lip narrow with numerous marginal fringe barbels, each simple, bifid, or trifid. Maxillary barbel short, even with or slightly longer than marginal fringe barbels on lower lip, with simple or bifid secondary barbels. Lower lip well developed with conspicuous median notch; surfaces covered with numerous elongate filaments; and marginal fringe barbels simple. Premaxillary teeth 2-4 on each side, each tooth consisting of slender stalk ending in enlarged bilobed crown; outer lobe small, rounded or conical; inner lobe large, rounded or conical. Buccal papillae behind premaxillary teeth short, about the length of premaxillary teeth, arranged in cluster of approximately 16. Dentary teeth 4-8 on each side; less than half the length of premaxillary teeth; structure similar to that of premaxillary teeth except lobes usually shorter, more rounded.

Total plates in lateral series 33-34 (modally 33). Anterior 17-18 lateral plates with two parallel odontode keels widely separated, converging at midline on caudal peduncle; posterior (coalesced) lateral plates 15-17 (modally 15). Post-anal plates 19-21 (modally 20). Lateral abdominal plates 6-8 (modally 7), rectangular and elongate. Posterior median abdominal area with polygonal plates, largest and most developed on pre-anal shield, becoming smaller and loosely joined anteriorly, ending with smaller plates concentrated in center with naked areas on either side between lateral abdominal plates; area covering pectoral girdle mostly naked, with isolated clusters of plates usually present near bases of pectoral fins posterior to gill openings ( Fig. 4c ).

Dorsal fin when depressed reaching eighth or ninth plate posterior to its origin; distal margin slightly concave when erected. Pectoral fin when depressed reaching seventh lateral plate posterior to cleithrum; distal margin straight to slightly concave when erected. Unbranched pelvic-fin ray (spine) longest, reaching to anterior third of anal-fin length. Anal fin when depressed reaching seventh plate posterior to its origin; distal margin convex when erected. Distal margin of caudal fin concave, upper unbranched ray produced into long filament broken in all specimens examined.

Color in alcohol. Ground color tan to pale yellow. In largest specimen (138.1 mm SL), dark brown blotches irregularly distributed on dorsal surface of head and trunk with five dark brown transverse bands on dorsum from middle of dorsal fin to caudal peduncle; blotches on head inconspicuous and transverse bands present, but faded in smaller specimens (76.6-103.6 mm SL). Dorsal surfaces of upper lip lightly sprinkled with melanophores in large specimen, without melanophores in smaller specimens. Ventral surfaces pale yellow or cream. Pectoral and dorsal fins heavily pigmented with melanophores; dorsal fin with dark pigment on basal and distal third, with contrasting lightly pigmented or pale band in center. Pelvic fins with faint melanophores on distal two-thirds of fin; opaque, hyaline or with light sprinkling of melanophores in smaller specimens.Anal fin opaque or hyaline. Caudal fin with solid dark brown band on distal half, distal corner of upper lobe clear.

Variation. A single specimen (AMNH 74474, 138.1 mm SL; Fig. 8 ) from rio Mawarinuma (upper rio Negro drainage) is larger and more boldly patterned than specimens from deep channel habitats of the rio Negro. The rio Mawarinuma specimen also has larger eyes and well developed iris operculum (vs. slightly developed or inconspicuous in rio Negro specimens). This individual is identified as Loricaria lundbergi on the basis of abdominal plate arrangement, pigmentation, and plate counts, all of which are consistent with the remaining six specimens collected via bottom trawls from the deeper rio Negro habitats. A relationship between eye size and capture depth could not be demonstrated for L. lundbergi for lack of sufficient available material with data on capture depth (but see Discussion, below).

Sexual dimorphism. None observed.

Distribution and ecology. Loricaria lundbergi is known from geographically disparate localities in the rio Negro system ( Fig. 6 ). Six specimens, including INPA 28854 (holotype, 103.6 mm SL), ANSP 178694 (1 c&s, 76.8 mm SL), INPA 28855 (2, 76.6-80.4 mm SL), andANSP 187412 (2, 84.2-92.4 mm SL) were collected in bottom trawls at depths ranging from 8 to 19 m and at distances of 75 to 150 m from the shoreline, about 5 km upstream of the mouth of rio Branco (J. G. Lundberg et al. unpubl. data). A single specimen (AMNH 74474, 138.1 mm SL) was collected in the rio Mawarinuma in the upper rio Baria drainage, a tributary of the rio Casiquiare in Venezuela. All collections of this species were made in black-water habitats. Stomach contents of a single dissected specimen (ANSP 178694, 76.6 mm SL) collected in depths of 7.9 to 19.1 m contained aquatic insect larvae (order Diptera , family Chironomidae ), sclerotized body parts of unidentified insect larvae, organic detritus and sand.

Etymology. In honor of Dr. John G. Lundberg, Curator and Chaplin Chair of Ichthyology, Academy of Natural Sciences of Philadelphia, for his leading role in the Calhamazon Project and many outstanding contributions to Neotropical ichthyology.

Figures

Fig. 8. Loricaria lundbergi, paratype, AMNH 74474 (138.1 mm SL) rio Mawarinuma (Baria-Negro dr.), at Neblina base camp, Amazonas, Venezuela.

Fig. 4. Variation in abdominal plate development and configuration in Loricaria. a. L. pumila; b. L. spinulifera; c. L. lundbergi; d. L. simillima.

Fig. 9. Bivariate scatterplot and linear regression lines showing relationship between head width and standard length in Loricaria lundbergi (R2 = 0.991, P <0.0001) and L. parnahybae (R2 = 0.939, P <0.0001).

Fig. 10. Bivariate scatterplot and linear regression lines showing relationship between basicaudal plate length and head length in Loricaria lundbergi (R2 = 0.929, P <0.0005) and L. parnahybae (R2 = 0.865, P <0.0001).

Fig. 6. Geographic distributions of Loricaria lundbergi (type locality = 1), L. spinulifera (type locality = 2), and L. pumila (type locality = 3) based on material examined.