Simpsonichthys espinhacensis, Nielsen, Dalton Tavares Bressane, Pessali, Tiago Casarim & Dutra, Guilherme Moreira, 2017

Nielsen, Dalton Tavares Bressane, Pessali, Tiago Casarim & Dutra, Guilherme Moreira, 2017, A new annual fish of the genus Simpsonichthys (Cyprinodontiformes: Cynolebiidae) from the upper Rio Jequitinhonha basin, Brazil, Zootaxa 4263 (1), pp. 165-172 : 166-171

Simpsonichthys espinhacensis , new species

( Figs. 1–2 ; Table 1)

Holotype. MCNIP 1792, 45.7 mm SL, Brazil, Minas Gerais, Olhos D ´água, Vereda Volta da Capoeira, tributary of Ribeirão da Areia, Rio Jequitinhonha basin, 17°15'29.54"S 43°43'10.10"W, 0 8 Feb 2016, T. C. Pessali & T. A. Barroso.

Paratypes. All from Brazil, Minas Gerais, Olhos D ´água, Rio Jequitinhonha basin: MCNIP 1681, 4 +5CS, 18.2–43.6 mm SL, collected with holotype . MCNIP 1685, 2 , 27.6–38.0 mm SL, same locality as holotype, 20 Aug 2014, T. J. Sousa and B. Andreata . MCNIP 1686, 8, 18.3–25.8 mm SL, Ribeirão da Areia, 17°17'32.02"S 43°39'44.50"W, 0 8 Feb 2016, T. C. Pessali & T. A. Barroso. MPEG 34050, 2 +2CS, 22.7–30.9 mm SL, same locality as holotype, 0 7 Jan 2016, T. C. Pessali & A. A. Rodrigues . MZUSP 120736, 2, 21.3–30.9 mm SL, collected with holotype. ZUEC 13430, 1, 21.3 mm SL, collected with holotype. ZUEC 13479, 1 , 35.8 mm SL, same locality as holotype, 20 Aug 2014, T. J. Sousa & B. Andreata.

Diagnosis. Simpsonichthys espinhacensis is distinguished from all congeners by the frontal squamation Apatterned (versus E-patterned). Males of S. espinhacensis also differ from all congeners by the color pattern of body, reddish brown with light blue dots on each scales in males (versus red bars alternating with light blue bars in S. cholopteryx , S. nigromaculatus and S. parallelus ; or series of longitudinal light blue dots in S. boitonei , S. margaritatus , S. punctulatus , S. santanae , and S. zonatus ); the absence of contact organs at the pectoral fin (versus presence); and the presence of scales on anal-fin base (versus absence). Simpsonichthys espinhacensis further differs from S. boitonei , S. punctulatus , S. santanae , and S. zonatus by the iris red (versus light yellow) and posterior margin pectoral fin reaching the 1st or 2nd anal fin rays (versus 4th to 6th in S. boitonei and S. zonatus ; 4th to 7th in S. punctulatus and S. santanae ). The new species additionally can be diagnosed from S. boitonei and S. punctulatus by the caudal fin length, 20.3–27.6% of SL (versus 35.8–40.6% of SL and 40.8–41.3% of SL, respectively). Simpsonichthys espinhacensis can be further distinguished from S. punctulatus and S. zonatus by the eye diameter, 22.0–27.5% of HL (versus 34.7–35.0% of HL and 29.9–34.7% of HL, respectively).

Females of S. espinhacensis can be distinguished from all congeners by presenting the tip of pectoral fin reaching vertical anterior to pelvic fin (versus vertical at urogenital papillae or anus).

Description. Morphometric data presented in Table 1. Largest male specimen examined 45.7 mm SL, largest female 34.4 mm SL. Dorsal profile convex from snout to end of dorsal-fin base, approximately straight along caudal peduncle. Ventral profile slightly convex from tip of jaw to origin to end of anal-fin base, approximately straight along caudal peduncle. Body moderately deep, compressed, greatest body depth at vertical slightly ahead of anal fin origin.

Males Females

Holotype Range N Mean SD Range N Mean SD Head compressed, greatest depth at nape. Snout blunt. Mouth superior. Premaxillary teeth 33(1) or 37(1). Dentary teeth 40(1) or 43(1). Vomerine teeth absent. Eye positioned on sides of head. Branchial membranes joined at isthmus. Gill-rakers on first brachial arch 2+9(1) or 3+9(1). Branchiostegal rays 6(7). Urogenital papilla cylindrical and small in males, pocket-shaped in females.

Pectoral fin elliptical with 13*(22) or 14(6) rays. Posterior margin reaching vertical between insertion of 1st or 2nd anal-fin rays in males, and anterior to pelvic fin in females. Dorsal fin filamentous in males and rounded in females. Dorsal-fin with 16(1) or 18*(14) rays in males, and 14(4), 15(5), 16(2), or 18(2) in females. Dorsal fin rays in males gradually increasing in size, 13rd to 15th rays larger than remaining, 16th to 18th rays gradually decreasing in size. Dorsal-fin origin at vertical posterior to anal fin origin, between 2nd or 3rd anal-fin rays in males and females. Dorsal fin with 18(3) pterygiophores in males and 16(4) in females. First pteryogiophore between to neural spine of 9th and 10th vertebrae in males, and 10th and 11th vertebrae in females. Pelvic fin short and pointed with 5(6) or 6*(18) rays. Posterior margin reaching 2nd or 3rd anal-fin rays in males, and vertical between anus and urogenital papilla in females. Pelvic-fin base with interspace. Anal fin filamentous in males and rounded in females. Anal fin with 16(2), 17(4), 18*(19) or 19(3) rays. Anal-fin rays in males gradually increasing in size, 13rd to 15th rays larger than remaining, 16th to 19th rays gradually decreasing in size. Anal fin with 18(2) pterygiophores, first one between 8th or 9th pleural ribs in males, and 9th or 10th in females. Caudal fin rounded, with 22(1), 24(2), 25(2), 27(2) or 28*(21) rays.

Scales large, cycloid. Body and head entirely scaled. Frontal squamation A-patterned. Supraorbital scales absent. Longitudinal series with 25(1), 26(1), 27*(15) or 28(5) scales. Transversal series of scales from dorsal-fin origin to pelvic-fin origin 10*(20) or 11(3). Single row of scales on basal portion of anal fin. Circumpeduncular scales 12(2), 13(1) or 14*(19). Males presenting five rows of minute contact organs on each scale on head and flanks, reaching vertical through end of anal fin. Contact organs absent at pectoral fin in males.

Cephalic neuromasts: supraorbital 15–16, parietal 3, anterior rostral 3, posterior rostral 3, infraorbital 2 + 16– 18, preorbital 2, otic 2, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 1, preopercular 12–14, mandibular 12, lateral mandibular 2–3. Two neuromasts on caudal fin base. Total vertebrae 26(3) or 27(4). Pleural ribs 10(2).

Coloration in life—males. Based on the picture of the holotype ( Fig. 1 A). Overall background color of trunk and head reddish brown. All scales with a small metallic light blue dot in center. Ventral portion of head metallic gold. Tip of jaw and snout light brown. Circumorbital area reddish brown. Iris red with vertical black bar through middle of eye. Head with horizontal dark brown line ventrally from posterior first row of scales to preopercular region; then vertically to horizontal through dorsal portion of eye; posteriorly from that point to postero-dorsal portion of opercle; and vertically along posterior margin of opercle.

Pectoral fin hyaline. Dorsal fin reddish brown, with alternate light yellow elongated spots on anterior portion; posterior portion with rows of greenish blue rounded spots. Pelvic fin darkened. Anal fin reddish brown, with alternate hyaline bars on inter-radial membranes; tip of elongated anal-fin rays light black. Caudal fin reddish brown, with light blue dots along inter-radial membranes.

Coloration in life—females. Overall background color of trunk and yellowish brown ( Fig. 2 A). Flank with series of one to four vertically elongated black blotches. First to third blotches anterior to dorsal fin insertion and fourth on the middle of caudal peduncle. Overall background color of head yellowish brown, becoming progressively lighter ventrally. Iris light yellow with vertical black bar through middle of eye. Opercular region pale golden green. All fins hyaline.

Distribution and habitat. Known only from Vereda Volta da Capoeira and Ribeirão da Areia, headwater (775–800 meters a.s.l.) tributaries of the Rio Jequitinhonha basin, Minas Gerais state, Brazil ( Fig. 3 ). These are large flooded areas during the rainy season ( Fig. 4 A, D). During this time of the year, water is relatively cold (24.6– 26.9°C), with pH ranging from 6.46 to 7.38, electric conductivity 0.04 to 0.47 mS/cm, and water salinity 0.02 to 0.23 ppt. The soil is hydromorphic with a thick layer of organic matter. During the dry season, the wetland is reduced to small pools and intermittent channels ( Fig. 4 C). The wetlands are dominated by herbaceous and grassy vegetation, with buriti palms ( Mauritia flexuosa ) ( Fig. 4 D). Simpsonichthys espinhacensis occurs sympatrically with Astyanax aff. fasciatus , Astyanax cf. lacustris , Astyanax sp., Characidium spp., Coptodon rendalli , Corydoras sp., Cyphocharax jagunco , Hasemania sp., Hoplias brasiliensis , Rhamdia aff. quelen and Synbranchus sp.

Etymology. The specific epithet is in reference to the Serra do Espinhaço, which was declared in 2005 a Biosphere Reserve by the United Nations Educational, Scientific and Cultural Organization (UNESCO) by its natural heritage ( Andrade & Domingues, 2012). The name “Serra do Espinhaço” (“Backbone range”) was proposed in 1822 by W. L. von Eschwege in allusion to the subsequent, longitudinally slender North-South oriented plateaus, whose shape resembles a vertebral column ( Derby, 1906).

Conservation status. The estimated area of occupancy of Simpsonichthys espinhacensis is 0.650 km 2. The known area of occurrence of S. espinhacensis has been progressively degraded by fire, water catchment, construction of embankments, and deforestation for eucalyptus plantations and cattle ( Fig. 4 E–F). Considering the present relevant threats to the species, Simpsonichthys espinhacensis could be classified as Critically Endangered (CR), according to the International Union for Conservation of Nature (IUCN) categories and criteria ( IUCN Standards and Petitions Subcommittee, 2016). Conservation measures needed for S. espinhacensis are the recovery of wetlands and the restriction of forestry activities in the area. However, enforcement of environmental laws by governmental agencies in the upper Jequitinhonha basin area is badly needed.

Remarks. The inclusion of the new species within Simpsonichthys is justified by the presence of all three synapomorphies recognized for that genus by Costa (2006): minute or absent pelvic fins, a reduced mesopterygoid, and the presence of five alternating bright blue and pink to red bars on head sides in males. The inclusion of the new species in the genus Simpsonichthys is further justified by the ventral process of posttemporal minute or absent and the flanks of males predominantly pink to red. These two latter features are also found in other genera of Cynolebiidae ( Costa, 2006) .

The genus Simpsonichthys is divided into two clades with separate and well defined geographical areas ( Costa, 2010). The species belonging to the eastern clade differ from the ones belonging to the western clade by the body size (near 40 mm SL versus near 25 mm SL), caudal fin without dark margin and subdistal blue line on caudal fin (versus presence of such coloration pattern), a distal stripe on dorsal and anal fins (versus dark gray distal stripes), pectoral fin reddish hyaline in males (versus hyaline), and presence of filaments in dorsal and anal fins in males (versus absence) ( Costa, 2006, 2007). Simpsonichthys espinhacensis presents all the characters described for the eastern clade, and consequently is considered herein as belonging to it.

Figures

FIGURE 1. Lateral view of Simpsonichthys espinhacensis, holotype, MCNIP 1792, male, 45.7 mm SL; Brazil, Minas Gerais State, Vereda Volta da Capoeira, Rio Jequitinhonha basin. A) Live specimen photographed in aquarium; B) same specimen after preservation.

FIGURE 2. Lateral view of Simpsonichthys espinhacensis, paratype, MPEG 34050, female, 26.0 mm SL; Brazil, Minas Gerais State, Vereda Volta da Capoeira, Rio Jequitinhonha basin. A) Live specimen photographed in aquarium; B) Same specimen after preservation.

FIGURE 3. Map of eastern portion of South America, showing the distribution of Simpsonichthys espinhacensis (black star). The symbol represent more than one locality.

FIGURE 4. Sites of occurrence of Simpsonichthys espinhacensis at Serra do Espinhaço, Rio Jequitinhonha basin, Minas Gerais State, Brazil. A – C) Vereda Volta da Capoeira; D) Ribeirão da Areia; E – F) Anthropogenic impacts recorded in the Vereda Volta da Capoeira.