Aspidoras psammatides, Britto & Lima & Santos, 2005

Britto, Marcelo R., Lima, Flávio C. T. & Santos, Alexandre C. A., 2005, A new Aspidoras (Siluriformes: Callichthyidae) from rio Paraguaçu basin, Chapada Diamantina, Bahia, Brazil, Neotropical Ichthyology 3 (4), pp. 473-479 : 474-477

Aspidoras psammatides , new species Figs. 1-5

Holotype. MNRJ 28407 (25.7 mm SL) Brazil, Estado da Bahia, município de Lençóis, rio Caldeirão , 12º39’33"S 41º22’12"W; A. C. A. Santos, 6 Nov 1999.

Paratypes. All from Brazil, Estado da Bahia, município de Lençóis : MNRJ 21269 (51, 15.4-27.8 mm SL) ; MZUSP 67194 (20, 17.1-27.6 mm SL); same data as holotype . MNRJ 21270 (26, 2 cs, 15.9-30.4 mm SL) ; MZUSP 67195 (20, 16.6-31.0 mm SL); rio Capivara , 12º37’19"S 41º22’35"W; A. C.A. Santos, 13 Mar 1999 . MNRJ 21708 (7, 14.4-21- 2 mm SL) rio Roncador , 12º42’01"S 41º21’26"W; A. C. A. Santos, 13 Mar 1999 . MNRJ 21709 (50, 2 cs, 15.0- 28.4 mm SL) rio Caldeirão , 12º39’33"S 41º22’12"W; A. C. A. Santos, 13 Mar 1999 . MNRJ 21710 (18, 1 cs, 16.7-24.9 mm SL) rio Roncador , 12º42’01"S 41º21’26"W; A. C.A. Santos, 6 Nov 1999 . MNRJ 21711 (47, 16.5-27.9 mm SL) rio Capivara , 12º37’19"S 41º22’35"W; A. C. A. Santos, 6 Nov 1999 . MNRJ 21712 (1, 23.2 mm SL) rio Ribeirão , 12º35’10"S 41º22’57"W; A. C. A. Santos, 6 Nov 1999 .

Diagnosis. Aspidoras psammatides differs from its congeners by the following exclusive features: poorly-developed pigmentation, restricted to minute scattered blotches on dorsal region of head and body, grouped in small, irregular blotches along lateral body plate junction (vs. dense pigmentation, in marbled or striped pattern); four or five caudal vertebra (vs. only three vertebra) anterior to compound caudal centrum, with neural and haemal spines placed posteriorly, close to post-zygapophyses; minor least interorbital distance (19.9 - 27.8% in HL vs. greater than 28% in HL); and postzygapophyses of precaudal vertebrae not showing dorsal expansions connected with its respective neural spine (vs. postzygapophyses connected with their respective neural spine).

Description. Morphometric data presented in Table 1. Head compressed with slightly convex dorsal profile; roughly triangular in dorsal view ( Fig. 2 ). Snout rounded. Head profile convex from upper lip to vertical through middle of parietosupraoccipital; body slightly convex from that point to base of last dorsal-fin ray. Postdorsal-fin body profile slightly concave to adipose-fin spine; markedly concave from this point to caudal-fin base. Ventral profile of body slightly convex from isthmus to anal-fin origin; slightly pronounced between pectoral fins. Profile markedly concave from first anal-fin ray to caudal-fin base. Body elongated; roughly cylindrical in cross section at pectoral girdle, gradually becoming more compressed toward caudal fin.

Eye rounded, dorso-laterally on head; orbit delimited dorsally by 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 naris diameter. Mouth small, subterminal, width nearly equal to bony orbit diameter. Maxillary barbel elongate, but not reaching anteroventral limit of gill opening.

M. R. Britto, F. C. T. Lima & A. C. A. Santos 475

Maxillary barbel slightly longer than outer mental barbel. Inner mental barbel fleshy. Small rounded papillae covering entire surface of all barbels, upper and lower lips, and isthmus. Gill membranes united to isthmus. Four branchiostegal rays covered by thick layer of skin; distal two rays united at their tips by branchiostegal cartilage. Teeth on upper pharyngeal tooth plate 28 (2) or 34 (1), and on fifth ceratobranchial 22 (1) or 24 (2).

Nasal, frontal, sphenotic, compound pterotic, and parietosupraoccipital visible externally, all covered by thin layer of skin and bearing minute scattered odontodes. Frontal fontanel elongate, ellipsoid, covered by thin layer of skin, and reaching anterior border of parieto-supraoccipital. Parietosupraoccipital fontanel round, located in the middle of bone Nasal slender, slightly curved laterally, mesial border contacting frontal and mesethmoid. Frontal roughly rectangular; anterior expansion in contact with nasal bone and mesethmoid, posterior portion contacting sphenotic and parieto-supraoccipital. Sphenotic trapezoid in shape, contacting parieto-supraoccipital dorsally, compound pterotic posteriorly, and second infraorbital ventrally. Compound pterotic roughly pipe-shaped, with slender posterior expansion contacting first dorsal body plate dorsally, and first lateral-line ossicle posteriorly. Ventral margin of compound pterotic contacting opercle and cleithrum. Parieto-supraoccipital quadrangular with posterior expansion triangular and short, not reaching nuchal plate ( Fig. 2 ).

Two narrow infraorbital bones nearly restricted to laterosensory canal, externally visible, covered by thin layer of skin. Both bearing few minute odontodes. First infraorbital with very short anterior expansion (flange; Fig. 3). Minute odontodes-bearing platelets dorsally on orbit. Opercle exposed, ovoid in shape and roughly elongate, with angular free border. Preopercle externally visible, slender and covered by thin layer of skin. Interopercle triangular, covered by thin layer of skin.

Trunk lateral-line composed of one perforated dorsolateralbody plate and two laterosensory canals, reduced to small ossicles. Lateral-line canal entering neurocranium through compound pterotic, splitting posterior of sphenotic into pterotic and preoperculomandibular branches, each with single pore. Sensory canal continuing through compound pterotic, entering sphenotic as temporal canal, which splits into two branches: one branch giving rise to infraorbital canal, other branch entering frontal through supraorbital canal. Supraorbital canal with two branches: epiphyseal branch opening in frontal bone, and anterior branch running through nasal bone. Nasal canal with single opening at each end. Infraorbital canal running through entire second infraorbital, extending to infraorbital 1 and opening into two pores. Preoperculomandibular branch not connected to preoperculomandibular canal, which runs through entire preopercle with three openings, leading to pores 3, 4, and 5, respectively.

Body plates with minute odontodes restricted to posterior margins. Nuchal plate exposed. Cleithrum exposed. Dorsolateral body plates between parieto-supraoccipital process and nuchal plate not touching counterparts, leaving narrow naked area; specimens less than 26.4 mm SL also shows naked area between last dorsal-fin ray and first preadipose platelet. Dorsolateral body plates 26 (2), 27* (24), 28 (24), or 29 (2); ventrolateral body plates 24 (19), 25* (25), or 26 (8); dorsolateral body plates along dorsal-fin base 6 (12) or 7* (40); dorsolateral body plates from adipose fin to caudal-fin base 8 (2), 9 (8), 10* (23), 11 (18), or 12 (1); preadipose platelets 2 (1), 3 (11), 4* (35), 5 (4), or 6 (1). Precaudal vertebrae 7 (2) or 8 (3); caudal vertebrae 18 (5). Four to five caudal vertebra, anterior to compound caudal centrum, with neural and haemal spines placed posteriorly, close to post-zygapophyses ( Fig. 4 ). Post-zygapophyses of precaudal vertebrae reduced, not showing dorsal expansions connected with respective neural spine ( Fig. 5 ). Five (4) or seven (1) pairs of ribs, first pair conspicuously larger than others.

Dorsal fin roughly triangular; its origin just posterior to third dorsolateral body plate. Dorsal spine shorter than first five branched rays. Distal tip of spine with minute-segmented unossified portion. Anterior and posterior border of dorsal spine smooth. Dorsal-fin rays I, 8 in all specimens examined. Adipose fin roughly triangular; its origin separated from base of last dorsal-fin ray by seven to eight dorsolateral body plates. Anal fin roughly ovoid; its origin located just posterior to 13th to16th ventrolateral body plates, at vertical through anterior margin of adipose-fin spine. Anal-fin rays ii,5,i *; one specimen (MNRJ 21710, 24.6 mm SL) ii,4,i. Pectoral fin roughly rounded; its origin located just posterior to gill opening. Ossified portion of pectoral spine shorter than first five branched rays. Distal tip of spine with minute-segmented unossified portion. Pectoral spine with well-developed serrations along entire posterior border. Pectoral-fin rays I,9* (27) or I,10 (25). Pelvic fin ellipsoid; its origin just below second ventrolateral body plate, at vertical through base of third branched dorsalfin ray. Pelvic-fin rays i, 5. Caudal fin bilobed; both lobes equal in size. Principal caudal-fin rays i,6/6,i *, one specimen (MNRJ 21711, 27.4 mm SL) i,6/5,i; upper procurrent caudal-fin rays iv; lower procurrent caudal-fin rays iv.All fins with minute odontodes scattered over all rays.

Color in alcohol. Ground coloration of head light brown to yellowish white. Several chromatophores clustered in minute brown dots scattered over dorsal and lateral surface of head. Dots more concentrated on posterodorsal portion of opercle and on side of snout forming discrete stripe from anteroventral region of orbit to snout tip. Larger individuals (up to 26.4 mm SL) with dots grouped in small blotches. Small specimens with scattered minute brown blotches on anterior portion of snout. All barbels yellowish white; few chromatophores present on barbels in some individuals.

Ground color of trunk light brown to yellowish white. Dif- collected in four of these tributaries, rio Roncador, rio Capivara, rio Ribeirão and rio Caldeirão. The rio São José and its tributaries are all blackwater rivers. The type locality of Aspidoras psammatides , rio Caldeirão, has sandy and rocky bottom, with little amount of riparian and submerged vegetation.

Distribution. Aspidoras psammatides is known only from tributaries of the upper rio Paraguaçu, a coastal river basin from eastern Brazil ( Fig. 6 )

Etymology. Psammatides , after “Psammatos psammatides”, “the sand sorcerer”, a character of J.R.R. Tolkien’s book “Roverandom”, from the Greek psammos, sand, and ides, son of. In allusion to the sand-dwelling behavior of the species. A noun in apposition.

fuse brown blotch on middle region of cleithrum. Minute dark brown dots scattered over entire surface of trunk; more concentrated on dorsal region. Dots clustered around bases of dorsal spine, last dorsal-fin ray and adipose-fin spine, respectively. Small diffuse brown blotches along lateral junction of body plates, from cleithrum to caudal peduncle. Blotches varying in number from five to (more commonly) eight blotches. Ventral surfaces of body yellowish white.

Interradial membrane of all fins hyaline. Dorsal fin with few chromatophores scattered on dorsal spine and first two to three adjacent rays, scarcely present on their tips. Ground color of anal-fin rays yellowish white. Some individuals with sparce chromatophores on base of rays. Few chromatophores scattered over adipose-fin spine; some individuals with chromatophores also on adipose-fin membrane adjacent to spine and on its apex.All pectoral-fin rays and spine yellowish white. Larger specimens with sparse chromatophores on first two branched rays. Pelvic-fin rays hyaline. Caudal-fin rays yellowish white with several chromatophores clustered in three-four patches restricted to the three outermost rays of both lobes. Color in life very similar to that of preserved specimens.

Figures

Fig. 1. Aspidoras psammatides, holotype, MNRJ 28407, 25.7 mm SL, Brazil, Estado da Bahia, município de Lençóis, rio Caldeirão.

Fig. 2. Dorsal view of head of Aspidoras psammatides, holotype, MNRJ 28407, 25.7 mm SL.Arrow:naked groovebetween parieto-supraoccipital posterior process and nuchal plate.

Fig. 4. Detail of the region anterior to the compound caudal centrum of Aspidoras psammatides, paratype, MNRJ 21709, 22.6 mm SL, showing neural and haemal spines close to its respective post-zygapophyses.

Fig. 5. Detail of the dorsal region of precaudal vertebrae of Aspidoras psammatides, paratype, MNRJ 21709, 22.6 mm SL, showing their post-zygapophyses not connected with respective neural spine (arrows).

Fig. 6. Map of upper course of rio Paraguaçu showing the distribution of Aspidoras psammatides (squares). 1: rio Santo Antônio; 2: rio São José; 3: rio Ribeirão; 4: rio Capivara; 5: rio Caldeirão; 6: rio Roncador; arrow: type locality.