Geophagus rufomarginatus, Mattos & Costa, 2018

Mattos, Jose L. O. & Costa, Wilson J. E. M., 2018, Three new species of the ' Geophagus ' brasiliensis species group from the northeast Brazil (Cichlidae, Geophagini), Zoosystematics and Evolution 94 (2), pp. 325-337 : 327-328

Geophagus rufomarginatus sp. n. Fig. 2 , Table 2

Material.

Holotype. UFRJ 9994, 97.8 mm SL; Brazil, Bahia state: Porto Seguro municipality: small stream crossing the road BA-001, Rio Buranhem Basin , 16°26'17"S, 39°10'47"W, altitude about 10 m asl; A. M. Katz, F. R. Pereira and J. L. O. Mattos, 20 July 2016.

Paratypes. UFRJ 11198, 6, 89.5-104.1 mm SL, 1, 94.3 mm SL (d&c); UFRJ 11031, 2, 15.9-41.6 mm SL (DNA); CICCAA 01378, 2, 94.3-97,6 mm SL; collected with holotype. UFRJ 9741, 1, 103.5 mm SL; UFRJ 9518, 7, 20.4-40.9 mm SL; Brazil, Bahia state: Eunápolis municipality: Rio Buranhém crossing the road BR-101, Rio Buranhem Basin , 16°24'47"S, 39°35'14"W, altitude about 65 m asl; F. R. Pereira and F. P. Ottoni, 23 June 2013 . UFRJ 9519, 6, 17.3-40.7 mm SL (DNA); Brazil, Bahia state: Rio Buranhém under BA-001 road bridge, between the towns of Porto Seguro and Trancoso , Rio Buranhem Basin , 16°23'32"S, 39°17'08"W, altitude about 20 m asl; F. R. Pereira and F. P. Ottoni, 24 June 2013 .

Diagnosis.

eophagus Geophagus rufomarginatus is distinguished from all other species of ' G. ' brasiliensis group by having: dorsal-fin lappets with red edges (vs. grey or dark brown), presence of longitudinal series of small light blue spots between anal-fin spines and rays (vs. never this pattern), and non-denticulated gill-rakers (vs. denticulated). In addition, it is distinguished from all other species of the ' G. ' brasiliensis species group, except G. obscurus and G. santosi , by having an oblique iridescent blue zone between the humeral region and the anterior portion of the dorsal-fin base (vs. iridescent blue zone absent). It is also distinguished from G. diamantinensis by the absence of a dark brown mark on the humeral region (vs. presence); presence of iridescent blue to green spots on the opercular region (vs. whole opercular region golden); and absence of a horizontal dark brown band on the snout (vs. presence).

In addition, G. rufomarginatus is also distinguished from all other species of ' G. ' brasiliensis group by 13 unique nucleotide substitutions: COI 285 (T> C), COI 330 (T> C), COI 333 (T> C), COI 591 (A> C), COI 642 (C> T), CYTB 60 (C> T), CYTB 129 (C> T), CYTB 186 (C> T), CYTB 309 (C> T), CYTB 324 (A> G), CYTB 886 (T> C), CYTB 906 (A> G), CYTB 958 (C> T); it is similar to G. iporangensis and G. brasiliensis and distinguished from all other species of the ' G. ' brasiliensis group by four unique nucleotide substitutions: COI 700 (T> C), CYTB 165 (C> T), CYTB 582 (A> G), CYTB 1078 (A> C).

Description.

Morphometric data appear in Table 2 . Medium sized species, largest specimen examined 104.2 mm SL. Body relatively slender and compressed. Dorsal profile slightly convex on head, convex from nape to end of dorsal-fin base, approximately straight on caudal peduncle; no adipose nuchal protuberance. Ventral profile straight to slightly convex from lower jaw to pelvic-fin insertion, slightly convex between belly and end of anal-fin base, nearly straight on caudal peduncle. Caudal peduncle approximately as deeper as long. Greatest body depth at level of first dorsal-fin spine. Snout moderately pointed; nostrils located between tip of snout and anterior margin of orbit. Mouth subterminal, distal tip of maxilla not reaching vertical through anterior margin of orbit. Lower lip fold moderately deep. Lower jaw slightly shorter than upper one. Eye near dorsal profile of head. Opercle not serrated.

Insertion of first dorsal-fin spine slightly anterior to vertical line through posterior-most margin of opercle. Tip of dorsal-fin pointed, reaching 30-90% of caudal-fin length, shorter and rounded in specimens 40.0 mm SL or smaller. Tip of anal fin pointed, reaching 30-50% of caudal-fin length, shorter and rounded in specimens 43.0 mm SL or smaller. Caudal fin subtruncate. Pectoral fin trapezoidal with rounded extremity, posterior margin posteriorly surpassing flank blotch. Tip of pelvic-fin pointed, short, reaching insertion of 1st anal-fin spine in larger specimens, shorter and rounded in specimens 50.0 mm SL or smaller, reaching between urogenital papilla and insertion of first anal-fin spine. Pelvic-fin filaments absent. Anal-fin origin at vertical between insertion of 13th dorsal-fin spine and 1st dorsal- fin ray. Dorsal fin XIV + 12-13 (23); anal fin III + 9-10 (23); pectoral-fin rays 15 (23); pelvic fin I + 5 (26). Caudal-fin rays iv + 16 + iv (5).

Side of head covered with cycloid scales, ventral surface of head and snout without scales. Chest, trunk and caudal peduncle covered with ctenoid scales. Scales on head smaller than scales on chest and flank. Dorsal and anal fins without scales. About one fourth of caudal fin covered with small, delicate scales. Two scale rows between lateral lines. Scales of dorsal-fin origin row 5; scales of anal-fin origin row 6; longitudinal series of scales 26; cheek scale row 5; upper lateral line scales 18, lower lateral line scales 11 + 2; circum-peduncular scale rows 16.

Premaxillary teeth conical, hyaline with red tip, slightly curved posteriorly; one regular outer row of teeth, increasing in size on symphysis; proximal teeth smaller and irregularly arranged. Dentary teeth with similar arrangement, but slightly smaller. Five branchiostegal rays. Urohyal with strong anterior constriction. Gill-rakers on first branchial arch: first ceratobranchial 12, articulation 1, first epibranchial 9. Ceratobranchial rakers short, blunt and denticulated, except on fourth ceratobranchial proximal margin and fifth ceratobranchial distal margin, conical and non-denticulated. Anterior teeth of third pharyngobranchial and fifth ceratobranchial small, thin and slightly curved anteriorly, proximal posterior teeth large, robust and circular in cross section. Distal posterior teeth of the fifth ceratobranchial laterally compressed and with one or two cuspids. Five dentigerous plate on fourth pharyngobranchial. Fifth ceratobranchial subtriangular, with concave posterior margin. One supraneural. Proximal radial of dorsal fin 25 + 1; proximal radial of anal fin 10 + 1; pleural ribs 13, epipleural ribs 12; vertebrae 14 + 14.

Colouration in life.

Flank yellowish brown with seven broad dark brown bars and one dark brown longitudinal stripe; dark brown bars and stripe often overlapped and without visible limits in live specimens, conspicuously delimited in preserved specimens. Pale blue iridescence on anteroventral portion of flank and small metallic blue dots on centre of scales of middle portion of flank and caudal peduncle. Rounded dark brown spot on fifth trunk bar, sometimes inconspicuous in live specimens; similar and smaller spot on middle of posterior portion of caudal peduncle. Oblique iridescent blue zone between humeral region and anterior portion of dorsal-fin base. Dorsum yellowish brown, chest and belly pinkish white.

Head greyish brown with ventral region lighter, branchiostegal region light red. Infra-orbital area with small metallic blue dots, most of them coalesced. Opercular region background colour yellowish brown. Opercular and temporal regions with few elliptical, small and large metallic blue spots spread through opercle. Iris golden brown, with dark brown bar through orbit not aligned to any portion of supra-orbital and infra-orbital stripes. Dark brown supra-orbital stripe extending from nape to posterodorsal margin of orbit, and dark brown infra-orbital stripe, approximately vertical, running between ventral margin of orbit and preopercle angle. Dorsal fin brownish yellow on basal portion, becoming reddish orange on distal and posterior portions, with metallic blue dots aligned between rays; marginal lappets with red edges; dark brown pigmentation concentrated at first two dorsal-fin spines. Anal fin reddish orange with small metallic blue spots, to brownish yellow with metallic blue lines parallel to rays and spine on anteriormost portion of fin; intense blue iridescence on distal portion of anal fin. Caudal fin reddish orange, to brownish yellow on posterodorsal corner, with small metallic blue rounded dots, vertically coalesced to form metallic blue bars on anterior portion; posterior margin dark bluish grey. Pectoral fin yellowish hyaline. Pelvic-fin spine light yellowish brown, anterior pelvic-fin rays light yellowish brown with metallic bluish stripes parallel to rays, region around last rays hyaline.

Colouration in alcohol.

Similar to colouration in life, except for metallic marks becoming dark brown on flank and light grey on fins; red and dark brown pigmentation fainted.

Distribution.

Known only from the middle and lower sections of the Rio Buranhém Basin, at altitudes of about 65 m above sea level or less, Bahia state, northeast Brazil (Fig. 3 ).

Etymology.

From the Latin marginatus (edge, border, margin) and rufo (red), an allusion to the colour pattern in life of the dorsal-fin lappets.

Figures

Figure 2. Geophagus rufomarginatus, UFRJ 9994, holotype, 96.8 mm SL; Brazil: Bahia: Rio Buranhem Basin. Scale bar 10 mm. Photograph by J. L. O. Mattos.

Figure 3. Geographical distribution of the ' Geophagus ' brasiliensis species group in northeast Brazil: red star, G. itapicuruensis; red triangle, G. obscurus; yellow triangle, G. diamantinensis; red circle, G. santosi; black diamond, G. multiocellus; yellow circle, G. rufomarginatus. Raw data set source was obtained from Natural Earth public domain (http: // www. naturalearthdata. com).