Geophagus santosi, 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 : 332-335

Geophagus santosi sp. n. Figs 5 , 6 , Table 4

Material.

Holotype. UFRJ 11765, 99.7 mm SL; Brazil: Bahia state: Ituberá municipality: Rio Mariana upstream of Cachoeira da Pancada , Area de Protecao Ambiental Michelin , 13°46'32"S, 39°09'29"W, altitude about 15 m asl; W. J. E. M. Costa et. al., 21 February 2014.

Paratypes. UFRJ 9998, 3, 92.0- 113.4 mm SL (DNA); CICCAA 01380, 1, 99.5 mm SL; collected with holotype. UEFS 10336, 2, 78.1-94.4 mm SL, 1, 78.06 mm SL (C&S); UEFS 10519, 1, 115.0 mm SL, 1, 58.2 mm SL (C&S); UEFS 11585, 8, 69.5-148.4 mm SL; UEFS 10098, 7, 114.3- 164.3 mm SL; Brazil: Bahia state: Ituberá municipality: Rio Mariana, Michelin APA, approximately 13°46'42"S, 39°09'32"W (approx.), altitude about 15 m asl; A. C. A. Santos et al., October 2007 .

Diagnosis.

Geophagus santosi is distinguished from all other species of the ' G. ' brasiliensis group by having dorsal and anal fins with blue stripes parallel to fin rays on their longest portion (vs. transverse blue bands crossing rays or fins with dots), and basal portion of caudal-fin with short, longitudinal bluish-white lines (vs. dots or bars). Geophagus santosi is similar to G. rufomarginatus and G. obscurus , and distinguished from all other species of the ' G. ' brasiliensis group, by the presence of an oblique iridescent blue zone between the humeral region and the anterior portion of the dorsal-fin base (vs. absence of an iridescent blue zone). Furthermore, it is also distinguished from G. obscurus by the presence of an oblique suborbital row of aligned, small iridescent blue marks, not extending to cheek (vs. suborbital iridescent blue marks irregularly arranged extending to the cheek) and chest profile straight in lateral view (vs. convex); from G. rufomarginatus by possessing dorsal-fin lappets with grey or dark brown edge (vs. red) and presence of denticles on the first branchial arch gill-rakers (vs. absence); from G. itapicuruensis by having XIV spines on dorsal fin (vs. XIII) and lateral spot rounded (vs. elliptical); from G. diamantinensis by the absence of a dark brown mark on the humeral region (vs. presence), absence of a horizontal dark brown band on the snout (vs. presence), and urohyal bone with strong constriction (vs. with gentle anterior constriction); and from G. brasiliensis by having a terminal mouth (vs. sub-dorsal).

Geophagus santosi is also distinguished from all species of ' G. ' brasiliensis group by 20 unique nucleotide substitutions: COI 143 (T > C), COI 291 (A > G), COI 523 (G > A) COI 564 (T > A) COI 589 (C >T), CYTB 69 (A >G), CYTB 78 (C > T), CYTB 231 (A >G), CYTB 279 (C > T), CYTB 297 (A > C), CYTB 327 (C > T), CYTB 447 (C >A), CYTB 606 (A > G), CYTB 609 (C > T), CYTB 687 (A > G), 735 (C > T), CYTB 801 (T > C), CYTB 852 (T > C), CYTB 915 (A > T), CYTB 1090 (A > G). It is similar to G. itapicuruensis and G. multiocellus and distinguished from all other species of ' G. ' brasiliensis group by three unique nucleotide substitutions: COI 678 (A > G), CYTB 114 (A > G), CYTB 927 (A > G).

Description.

Morphometric data appear in Table 4 . Medium sized species, largest specimen examined 164.3 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 convex from lower jaw to pelvic-fin insertion, gently straight between belly and insertion of first anal-fin spine, nearly straight on anal-fin base, nearly concave on caudal peduncle. Caudal peduncle slightly longer than deep. Greatest body depth at level of first dorsal-fin spine insertion. 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 or aligned in a vertical line through posterior-most margin of opercular series. Tip of dorsal fin pointed, short, reaching 20-40% of caudal-fin length, even in larger specimens. Tip of anal fin pointed, reaching 20-40% of caudal-fin length. Caudal fin subtruncate. Pectoral fin trapezoidal with rounded extremity, posterior margin posteriorly surpassing flank blotch. Tip of pelvic-fin rounded or pointed, relatively short and reaching between urogenital papilla and insertion of 3rd anal-fin spine. Pelvic-fin filaments absent. Anal-fin origin at vertical between insertion of 13th and 14th dorsal-fin spine. Dorsal fin XIV + 13 (25); anal fin III + 9-10 (25); pectoral-fin rays 15-16 (25); pelvic fin I + 5 (25). Caudal-fin rays vi + 16 + vi (3).

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 fifth of caudal fin covered with small delicate scales. Two scale rows between lateral lines. Scales of dorsal-fin origin row 4; scales of anal-fin origin row 5; longitudinal series of scales 26-27; cheek scale row 5; upper lateral line scales 18, lower lateral line scales 9-11 + 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 10, articulation 1, first epibranchial 8. 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, 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 or six dentigerous plate on fourth pharyngobranchial, two of them could merge. Fifth ceratobranchial subtriangular, with concave posterior margin and robust. One supraneural. Proximal radial of dorsal fin 24 + 1; proximal radial of anal fin 10 + 1; pleural ribs 12, epipleural ribs 11; vertebrae 14 + 14.

Colouration in life.

Flank orangish 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. Longitudinal rows of metallic light green spots on ventral part of flank, between pectoral-fin insertion and caudal-fin base; spots approximately occupying most scale area. Rounded dark brown spot on fifth trunk bar, similar and smaller spot on middle of caudal peduncle. Oblique iridescent blue zone between humeral region and anterior portion of dorsal-fin base. Dorsum dark orangish brown, chest and belly light pinkish white.

Head side dark orange, ventral surface white; branchiostegal region dark orangish grey. Infra-orbital area with row of four to six small metallic greenish blue dots, sometimes two or three dots coalesced. Opercular region background orangish brown; opercular and temporal regions with scattered metallic greenish blue spots. Iris yellowish brown, with greenish blue iridescence on anterior and posterior portions, and dark brown bar through orbit not aligned to supra-orbital and infra-orbital stripes. Dark brown supra-orbital stripe extending from nape to postero-dorsal margin of orbit, and dark brown infra-orbital stripe, approximately vertical, running between ventral margin of orbit and pre-opercle angle. Dorsal fin pale brown on anterior portion, pale yellow on middle, pale orange on posterior region; oblique series of elongate drop-shaped metallic green spots on anterior two thirds of fin, light blue stripes parallel to fin rays on longest region of fin, and longitudinal rows of rounded light blue spots on posterior portion of fin; dark brown pigmentation most concentrated at first two dorsal-fin spines and distal half of third spine. Anal fin reddish orange, to yellowish orange on basal portion, with longitudinal metallic blue stripes between rays, and metallic blue spots on posterior region. Caudal fin reddish orange with transverse rows of small bluish white spots often coalesced to form narrow bars; basal portion of fin light yellowish orange with short, longitudinal bluish white lines. Pectoral fin pale orangish hyaline. Pelvic-fin spine light orangish brown, anterior pelvic-fin rays light orangish brown with metallic greenish blue 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 Rio Mariana, an isolated small coastal river of Bahia state, northeast Brazil (Fig. 3 ).

Etymology.

The name Geophagus santosi is in honour of Alexandre Clistenes Alcântara Santos, ichthyologist and friend, who is dedicated to the study of aquatic ecosystems of northeast Brazil.

Figures

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).

Figure 5. Caudal fin colour pattern. A Geophagus multiocellus, UFRJ 8217, topotype. B Geophagus santosi, UFRJ 9998, topotype. Scale bar 10 mm. Photographs by J. L. O. Mattos.

Figure 6. Geophagus santosi, UFRJ 11765, holotype, 110.6 mm SL; Brazil: Bahia: Mariana River. Scale bar 10 mm. Photograph by J. L. O. Mattos.