Aspidoras psammatides Britto, Lima & Santos, 2005

Tencatt, Luiz Fernando Caserta, Britto, Marcelo R., Isbrücker, Isaäc Jan Hendrik & Pavanelli, Carla Simone, 2022, Taxonomy of the armored catfish genus Aspidoras (Siluriformes: Callichthyidae) revisited, with the description of a new species, Neotropical Ichthyology (e 220040) 20 (3), pp. 1-159 : 113-121

Aspidoras psammatides Britto, Lima & Santos, 2005

( Fig. 58 )

Aspidoras psammatides Britto, Lima & Santos, 2005:473‒479 (original description; type locality: Caldeirão River , Bahia State, Brazil). — Ferraris , 2007:110 (listed). — Wosiacki et al., 2014:311 (morphological comparison). — Leão et al., 2015:585 (listed as comparative material). — Tencatt, Bichuette, 2017:21 (listed as comparative material).

Diagnosis. Aspidoras psammatides can be distinguished from all of its congeners by having extremely narrow frontal bone, with width conspicuously smaller than half of entire length (vs. relatively wide, with width equal to or slightly larger than half of entire length in A. albater , A. azaghal , A. gabrieli , A. lakoi , A. mephisto , and A. rochai ; narrow, with width slightly smaller than half of entire length in A. depinnai , A. poecilus , A. raimundi and A. velites ; ranging from narrow, with width slightly smaller than half of entire length, to relatively wide, with width equal to or slightly larger than half of entire length in A. fuscoguttatus ). Additionally, A. psammatides can be distinguished from its congeners, except for A. albater , A. mephisto , and A. velites , by having anterior portion of infraorbital 1 with strongly reduced laminar expansion, not reaching or at same level as posterior margin of nasal capsule (vs. extremely well developed, reaching or surpassing anterior margin of nasal capsule in A. belenos ; well developed, surpassing middle of nasal capsule in A. depinnai and A. maculosus ; ranging from well developed, surpassing middle of nasal capsule, to extremely well developed, reaching anterior margin of nasal capsule in A. fuscoguttatus ; ranging from well developed, surpassing middle of nasal capsule, to extremely well developed, reaching or surpassing anterior margin of nasal capsule in A. kiriri ; ranging from poorly developed, slightly surpassing posterior margin of nasal capsule, to moderately developed, reaching middle of nasal capsule in A. aldebaran and A. lakoi ; moderately developed, reaching middle of nasal capsule in A. azaghal ; ranging from poorly developed, slightly surpassing posterior margin of nasal capsule, to extremely well developed, reaching anterior margin of nasal capsule in A. poecilus ; ranging from moderately developed, reaching middle of nasal capsule, to extremely well developed, reaching anterior margin of nasal capsule in A. raimundi ; at least well developed, surpassing middle of nasal capsule in A. rochai ); it can be distinguished from A. albater and A. mephisto by having inner laminar expansion of infraorbital 1 poorly developed (vs. expansion ranging from well developed to extremely well developed in A. albater ; moderately developed in A. mephisto ); from A. velites plus A. azaghal by the presence of dorsal-fin spinelet (vs. spinelet absent).

Description. Morphometric data available in Britto et al. (2005:475, tab. 1). Head compressed with convex dorsal profile; somewhat triangular or trapezoid in dorsal view. Snout well developed and pointed; or moderately developed and more rounded. Head profile convex from tip of snout to anterior nares; ascending slightly convex to nearly straight from this point to dorsal-fin origin; dorsal margin of orbit generally slightly elevated; region of parieto-supraoccipital slightly concave in some specimens. Profile slightly convex along dorsal-fin base. Postdorsal-fin body profile slightly concave or nearly straight to adipose-fin spine; slightly concave from this point to caudal-fin base. Ventral profile of body slightly convex from isthmus to pelvic-fin origin; region of gill opening slightly concave in some specimens; nearly straight from this point to anal-fin origin; slightly concave until caudal-fin base. Body acutely elliptical in cross section at pectoral girdle, gradually becoming more compressed toward caudal fin.

Eye rounded, located dorso-laterally on head; orbit delimited dorsally by lateral ethmoid, frontal and sphenotic, ventrally by infraorbitals. Anterior and posterior nares close to each other, only separated by flap of skin. Anterior naris tubular. Posterior naris close to anterodorsal margin of orbit, separated from it by distance equal to or smaller than naris diameter. Mouth small, subterminal, width larger than bony orbit diameter. Maxillary barbel moderate to relatively large in size, not reaching anteroventral limit of gill opening. Outer mental barbel ranging from slightly smaller to slightly larger than maxillary barbel. Inner mental barbel fleshy, with base close to its counterpart. Lower lip relatively well developed, forming moderately-developed triangular fleshy flap; or lower lip moderately developed, forming small semicircular fleshy flap. Small rounded papillae covering entire surface of all barbels, upper and lower lips, snout and isthmus.

Mesethmoid short; anterior tip long, larger than 50% of entire bone length (see Britto, 2003:123, ch. 1, state 0; fig. 1A); posterior portion wide, generally entirely covered by thick layer of skin; posterior portion partially exposed in some specimens. Nasal slender, curved laterally, inner margin generally with poorly-developed laminar expansion; outer margin with reduced laminar expansion; absent in some specimens; mesial border generally contacting frontal and mesethmoid.

Frontal elongated, extremely narrow, with width clearly smaller than half of entire length ( Fig. 3C ); anterior projection short, with size clearly smaller than nasal length; some areas of anterior margin covered by thick layer of skin in some specimens. Frontal fontanel relatively small, ellipsoid or somewhat rhomboid; posterior tip extension not entering anterior margin of parieto-supraoccipital. Sphenotic somewhat trapezoid, contacting parieto-supraoccipital dorsally, pterotic-extrascapular posteriorly, second infraorbital ventrally and frontal anteriorly. Pterotic-extrascapular roughly pipe-shaped, with posteriormost portion contacting first lateral-line ossicle, and ventral margin contacting opercle and cleithrum; posterior expansion almost entirely covering lateral opening of swimbladder capsule, leaving slender pseudotympanic area on its dorsal margin covered only by thick layer of skin. Parieto-supraoccipital wide, posterior process poorly developed, not contacting nuchal plate. Parieto-supraoccipital medial keel expanded ventrally; laminar, with posterior portion not reaching tip of posterior process. Parieto-supraoccipital fontanel small, roundish or ellipsoid; located medially on parieto-supraoccipital.

Two laminar infraorbitals with minute odontodes; infraorbital 1 large, ventral laminar expansion generally poorly developed; almost reduced to latero-sensory canal in some specimens; anterior portion with strongly reduced laminar expansion, not reaching or at same level as posterior margin of nasal capsule ( Fig. 59 ); inner laminar expansion poorly developed ( Fig. 5D ); small portions of external surface covered by thick layer of skin; infraorbital 2 small, slender; posterior laminar expansion generally poorly developed; almost reduced to latero-sensory canal in some specimens; inner laminar expansion poorly developed; posteroventral margin close but not directly contacting posterodorsal ridge of hyomandibula; variably contacting; dorsal tip contacting only sphenotic; small portions of external surface covered by thick layer of skin ( Fig. 59 ). Posterodorsal ridge of hyomandibula, close to its articulation with opercle, oblong, relatively slender; exposed, generally bearing small odontodes; dorsal ridge of hyomandibula, between pterotic-extrascapular and opercle, covered by thick layer of skin. Interopercle entirely covered by thick layer of skin; somewhat triangular, anterior projection moderately developed. Preopercle relatively slender, elongated, minute odontodes sparse on external surface. Opercle compact in shape, width larger than half of its length; free margin convex; posterodorsal region variably with smoothly concave area; without serrations and covered by small odontodes; some portions of bony distal margin irregular in some specimens.

Four branchiostegal rays decreasing in size posteriorly. Hypobranchial 2 somewhat triangular, tip ossified and directed towards anterior portion, posterior margin cartilaginous; ossified portion well developed, about twice size of cartilaginous portion. Five ceratobranchials with expansions increasing posteriorly; ceratobranchial 1 with small process on anterior margin of mesial portion; ceratobranchial 3 with continuous postero-lateral margin; ceratobranchial 5 toothed on postero-dorsal surface, 22 to 29(5) teeth aligned in one row. Four epibranchials with similar size; epibranchial 2 slightly larger than others, with small pointed process on laminar expansion of posterior margin; epibranchial 3 with triangular uncinate process on laminar expansion of posterior margin. Two wide pharyngobranchials (3 and 4), pharyngobranchial 3 with triangular laminar expansion on posterior margin; triangular laminar expansion with notches in some specimens. Upper tooth plate oval, with 28 to 34(5) teeth aligned in two rows on postero-ventral surface.

Lateral-line canal entering neurocranium through pterotic-extrascapular, branching twice before entering sphenotic: pterotic branch with single pore; preoperculomandibular branch conspicuously reduced, with single pore opening close to postotic main canal; postotic main canal widens just posterior to pterotic branch. Sensory canal continuing through pterotic-extrascapular, entering sphenotic as temporal canal, which splits into two branches: one branch giving rise to infraorbital canal, another branch entering frontal through supraorbital canal, both with single pore. Supraorbital canal branched, running through nasal bone. Epiphyseal branch of supraorbital canal relatively long, with pore opening close to frontal fontanel. Nasal canal with three openings, first on posterior edge, second on posterolateral portion and third on anterior edge; second pore fused with first pore in some specimens. Infraorbital canal running through entire second infraorbital, extending to infraorbital 1 and generally opening into two pores. Preoperculomandibular branch giving rise to preoperculo-mandibular canal, which runs through entire preopercle with three openings, leading to pores 3, 4, and 5, respectively; pore 3 opening at posterodorsal ridge of hyomandibula in some specimens.

Dorsal fin somewhat triangular, located just posterior to second or third dorsolateral body plate. Dorsal-fin rays II,8*(52), posterior margin of dorsal-fin spine smooth. Nuchal plate generally moderately developed in length and almost entirely exposed, bearing minute odontodes ( Fig. 60 ); spinelet generally short and partially exposed; spine moderately developed, adpressed distal tip surpassing middle portion of dorsal-fin base; or relatively well developed, adpressed distal tip slightly surpassing posterior origin of dorsal-fin base; anterior margin with small odontodes. Pectoral fin roughly triangular, its origin just posterior to gill opening. Pectoral-fin rays I,9*(27), I,10(25); posterior margin of pectoral spine with 18 to 19 moderately-developed serrations along almost its entire length; small region just posterior to origin of spine lacking serrations; some serrations directed towards origin of spine, perpendicularly directed or directed towards tip of spine; presence of bifid serrations in some specimens; base of branched rays with small laminar expansions on inner margin, generally more evident on first rays; laminar expansions with irregular margins in some specimens ( Fig. 61 ). Anteroventral portion of cleithrum partially exposed; posterolateral portion of scapulocoracoid reduced, externally visible. Pelvic fin oblong, located just below third or fourth ventrolateral body plate, and at vertical through second dorsal-fin branched ray. Pelvic-fin rays i,5*(52). Adipose fin roughly triangular, separated from posterior origin of dorsal-fin base by seven to nine dorsolateral body plates. Anal fin somewhat triangular, located just posterior to 14 th or 15 th ventrolateral body plates, and at vertical generally through origin of adipose-fin spine; or at vertical through region of preadipose platelets. Anal-fin rays ii,4,i(1), ii,5,i*(51). Caudal-fin rays i,11,i(1), i,12,i*(51), generally four dorsal and/or ventral procurrent rays; caudal fin bilobed, lobes with similar size.

Generally, three laterosensory canals on trunk; first ossicle tubular, second ossicle laminar, third lateral-line canal encased in third dorsolateral body plate. Body plates with conspicuous line of relatively large odontodes confined to posterior margins; dorsolateral body plates 26(2), 27*(24), 28(24), 29(2); ventrolateral body plates 24(19), 25*(25), 26(8); dorsolateral body plates along dorsal-fin base 6(12), 7*(40); dorsolateral body plates between adipose-fin spine and caudal-fin base 8(2), 9(8), 10*(23), 11(18), 12(1); preadipose platelets 2(1), 3(11), 4*(35), 5(4), 6(1); small platelets covering base of caudal-fin rays; small platelets disposed dorsally and ventrally between junctions of lateral plates on posterior portion of caudal peduncle. Anterior margin of orbit, above region of junction of frontal with lateral ethmoid, generally with small platelets; anterodorsal portion of orbit generally with small platelets. Ventrolateral portion of head variably with small platelets. Ventral surface of trunk scarcely covered by small platelets, generally more abundant and/or concentrated on region of pectoral girdle; absence of platelets in some specimens.

Vertebral count 25(3), 26(4); ribs 5(6), 7(1) first pair conspicuously large; parapophysis of complex vertebra moderately developed ( Fig. 8C ).

Coloration in alcohol. Ground color of body light or brownish yellow, with top of head dark brown. Posterodorsal portion of head, region below eye, opercle and cleithrum with scattered dark brown or black chromatophores. Snout covered by dark brown or black chromatophores on its dorsal surface; forming dark brown or black rounded, striated or irregular spots in some specimens; generally, with dark brown or black diffuse or conspicuous stripe from anteroventral portion of orbit to upper lip lateral area. Upper lip and maxillary barbel with dark brown or black chromatophores; or absence of chromatophores in these areas; area of lateral portion of upper lip with conspicuous concentration of dark brown or black chromatophores in some specimens; outer mental barbel generally lacking chromatophores. Dorsal series of four to five dark brown or black blotches, first on anterior portion of dorsal-fin base, second on posterior portion of dorsal-fin base, third on adipose-fin base, fourth, if present, middle portion of caudal peduncle, and fifth on caudal-fin base; blotches variably diffuse. Dorsal portion of body with conspicuous concentration of dark brown or black chromatophores between counterparts of dorsolateral body plates in some specimens. Ventral surface of trunk and region posterior to urogenital opening generally lacking dark brown or black chromatophores; region posterior to urogenital opening with dark brown or black chromatophores in some specimens. First dorsolateral body plate generally with conspicuous concentration of dark brown or black chromatophores; posterior margin of some dorsolateral plates and region of lateral line canals with conspicuous concentration of dark brown or black chromatophores in some specimens. Midline of flank with longitudinal series of five to ten small- to medium-sized conspicuous dark brown or black blotches; variably diffuse; blotches rounded, oblong or irregular. Dorsal half of dorsolateral body plates with dark brown or black chromatophores; region of anterior and posterior portions of dorsal-fin base, adipose-fin base, between adipose and base of caudal peduncle and base of caudal peduncle with more concentrated chromatophores, forming conspicuous blotches in some specimens. Ventral half of dorsolateral body plates and dorsal half of ventrolateral body plates with concentration of dark brown or black chromatophores, generally more evident on anterior portion of body and on area of flank midline blotches. Mid-ventral portion of ventrolateral body plates on area of flank midline blotches with concentration of dark brown or black chromatophores, generally more evident posteriorly to pelvic-fin origin; ventral portion of ventrolateral body plates with concentration of dark brown or black chromatophores, generally more evident posterior to anal-fin anterior origin, in some specimens. Dorsal fin with dark brown or black chromatophores, generally restricted to rays; almost entirely hyaline in some specimens; dorsal-fin base with conspicuous concentration of dark brown or black chromatophores, generally more concentrated on bases of first and last branched rays; spine generally covered by dark brown or black chromatophores. Pectoral fin with dark brown or black chromatophores on its dorsal surface, generally more evident on spine and first branched rays; or almost entirely hyaline; region of body around dorsal portion of pectoral-fin origin with concentration of dark brown or black chromatophores in some specimens. Pelvic fin generally hyaline. Adipose-fin membrane with dark brown or black chromatophores, generally more evident close to spine; almost entirely hyaline in some specimens; adipose-fin spine generally with dark brown or black chromatophores. Anal fin entirely or almost entirely hyaline; scarce dark brown or black chromatophores, generally restricted to bases of last branched rays in some specimens. Middle portion of caudal-fin base, posteriorly to last flank midline blotch, generally with small-sized dark brown or black blotch; blotch variably diffuse or fused with last midlateral blotch. Caudal fin with dark brown or black chromatophores, generally forming two to five short bars restricted to outermost rays of both lobes; short bars from dorsal and ventral lobes variably connected, forming clearly slender transversal large bars; almost entirely hyaline in some specimens.

Coloration in life. Similar to that observed in preserved specimens but with ground color of body grayish yellow in some specimens. Body covered by whitish yellow and green iridescent coloration ( Fig. 62A ).

Geographical distribution. Aspidoras psammatides is known only from the upper portion of the rio Paraguaçu basin in Bahia State, Brazil ( Fig. 55 ).

Ecological notes. The typical habitat of Aspidoras psammatides at the rio Capivara ( Fig. 62B ), a tributary to the rio Paraguaçu basin, presents highly transparent brownish water (tea colored), up to one meter depth, moderate current, and substrate composed by sand, gravel and larger rocks. The species was found in syntopy with Characidium clistenesi Melo, Espíndola (2016) . Apparently, both species forage next to each other, with no conspicuous interactions (Marcelo Melo, 2021, pers. comm.).

Conservation status. Aspidoras psammatides is currently known only from the upper rio Paraguaçu basin in Bahia. Although its known geographical distribution is relatively restricted, the available material suggests that the species is abundant in its natural habitat. Additionally, no threat to the species as a whole is currently known. According to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2019), Aspidoras psammatides can be classified as Least Concern (LC).

Material examined. In addition to the specimens examined by Britto et al. (2005:474), the following material was analysed. All from Brazil, Bahia, rio Paraguaçu basin. MZFS 2701, 20 of 36, 17.8‒28.7 mm SL, rio São José. MZFS 3955, 16, 17.9‒28.2 mm SL, rio São José. MZUSP 49245, 7, 21.7‒25.0 mm SL, Una River. MZUSP 93285, 22 of 27, 16.8‒28.1 mm SL, rio Capivara. MZUSP 120465, 5, 21.6‒28.4 mm SL, rio Capivara. MZUSP 120469, 19, 14.4‒20.9 mm SL, ribeirão de Baixo. MZUSP 120533, 49, 18.6‒27.7 mm SL, rio Capivara. UFBA 3678, 4 of 77, 15.9‒18.3 mm SL, rio da Invernada. UNT 9604, 18 of 40, 16.9‒23.3 mm SL, 2 CS of 40, 23.2‒27.3 mm SL, rio Roncador.

Figures

FIGURE 3 | Dorsal view of the head of CS specimens showing the three patterns of paired frontal bones (outlined in black) in Aspidoras: (A) narrow, with width of each frontal slightly smaller than half of its entire length (Aspidoras maculosus, UFBA 3291, 30.7 mm SL), (B) relatively wide, with width equal to or slightly larger than half of entire length (Aspidoras albater, MZUSP 40793, 29.4 mm SL), and (C) extremely narrow, with width clearly smaller than half of entire length (Aspidoras psammatides, UNT 9604, 27.3 mm SL). Scale bars = 1 mm.

FIGURE 5 | Dorsal view of the infraorbital series of CS specimens showing the four patterns of size and shape of the inner laminar expansion of infraorbital 1 (white arrows) in Aspidoras: (A) extremely well developed (Aspidoras albater, MNRJ 13080, 30.9 mm SL), (B) well developed (Aspidoras fuscoguttatus, NUP 12677, 36.1 mm SL), (C) moderately developed (Aspidoras poecilus, UNT 6249, 30.9 mm SL), and (D) poorly developed (Aspidoras psammatides, UNT 9604, 27.3 mm SL). Abbreviations: io1: infraorbital 1, io2: infraorbital 2. Scale bars = 1 mm.

FIGURE 8 | Ventral view of the complex vertebra in CS specimens of (A) Aspidoras belenos, paratype, UFRJ 4419 (ex-UFRJ 3861), 22.1 mm SL, with well-developed parapophysis, (B) Aspidoras albater, MNRJ 12571, 35.3 mm SL, with poorly-developed parapophysis, and (C) Aspidoras albater, MNRJ 12581 (disarticulated, indeterminate size), with moderately-developed parapophysis. Abbreviations: ccv: centrum of the complex vertebra, pcv: parapophysis of the complex vertebra. Scale bars = 1 mm.

FIGURE 55 | Map showing the geographical distribution of Aspidoras poecilus (type locality: red circle; non-type localities: black circles), A. psammatides (type locality: purple cross; non-type localities: white crosses), A. raimundi (type locality: red triangle; non-type localities: white triangles), A. rochai (type locality: red star), and A. velites (type locality: purple diamond; non-type localities: white diamonds). Each symbol may represent more than one locality.

FIGURE 58 | Aspidoras psammatides, holotype, MNRJ 28407, 25.7 mm SL, rio Caldeirão, Bahia State, Brazil. Dorsal (top), lateral (middle) and ventral (bottom) views. Photos by Victor de Brito.

FIGURE 59 | Lateral view of the head of CS specimen of Aspidoras psammatides, UNT 9604, 27.3 mm SL, showing its general infraorbitals pattern. Abbreviations: io1: infraorbital 1, io2: infraorbital 2, sph: sphenotic, pes: pterotic- extrascapular. Scale bar = 1 mm.

FIGURE 60 | Aspidoras psammatides, UNT 9604, CS, 27.3 mm SL, showing predorsal region of trunk in dorsal view. Abbreviations: np: nuchal plate, pso: parieto-supraoccipital. Scale bar = 1 mm.

FIGURE 61 | Aspidoras psammatides, UNT 9604, CS, 27.3 mm SL, showing dorsal view of the pectoral fin. Arrows indicate the small laminar expansions at the base of branched rays. Scale bar = 1 mm.

FIGURE 62 | Uncatalogued specimen of Aspidoras psammatides photographed alive (A) in its typical habitat at the rio Capivara, rio Paraguaçu basin (B). Photos by Marcelo Melo.