Leptolebias, MYERS, 1952

Costa, Wilson J. E. M., 2008, Monophyly and taxonomy of the Neotropical seasonal killifish genus Leptolebias (Teleostei: Aplocheiloidei: Rivulidae), with the description of a new genus, Zoological Journal of the Linnean Society 153 (1), pp. 147-160 : 149-153

LEPTOLEBIAS MYERS, 1952

Leptolebias Myers, 1952: 140 (type species: Cynopoecilus marmoratus Ladiges, 1934 , by original designation; first proposed as a subgenus of Cynolebias Steindachner, 1876 ).

Diagnosis: Distinguished from all other genera of the Cynopoecilina ( Notholebias , Cynopoecilus , and Campellolebias ) in having caudal fin elongate, longer than deep (vs. short, deeper than long), single anterior supraorbital neuromast ( Fig. 2 ) (vs. two or three), and distal third of dorsal fin in males without dark pigmentation (vs. extending pigmentation). Also distinguished from Notholebias by the absence of the second pharyngobranchial teeth, dermosphenotic and contact organs on male pectoral fin (vs. presence), opercular region with red reticulation in males (vs. red bars), and by having a wide, triangular basihyal ( Fig. 3 ) (vs. narrow, rectangular).

Distribution: Species of Leptolebias are found in the temporary pools of broad coastal plains, in two areas, separated by about 500 km: (1) between Maricá and Vila de Cava, Rio de Janeiro state, south-eastern Brazil ( Fig. 4 ), and (2) between Itanhaém, southern São Paulo state, and river basins draining into Paranaguá bay, Paraná state, southern Brazil ( Fig. 5 ).

LEPTOLEBIAS AUREOGUTTATUS ( CRUZ, 1974)

( FIGS 6–7)

Cynolebias aureoguttatus Myers, 1952: 131 [type locality: standing water along road between Paranaguá and the sea (road east of Paranaguá, according to label of material deposited in CAS); nomen nudum).

Cynolebias paranaguensis Myers, 1952: 131 (coastal plains near Paranaguá; nomen nudum).

Cynolebias aureoguttatus Cruz, 1974: 20 (type locality: ditch parallel to road between Paranaguá and Matinhos, Paraná, near km 11, at forest border, at an KEY TO SPECIES OF THE GENUS LEPTOLEBIAS

1a. Four neuromasts on caudal-fin base; horizontal golden lines present on caudal fin in males..........................2

1b. Two neuromasts on caudal-fin base; horizontal golden lines never present on caudal fin in males..................3

2a. Two dark-red stripes along entire dorsal and ventral submarginal parts of caudal fin in males; male caudal-fin stripes branching posteriorly; dark-red to dark-brown short transverse bars on basal portion of dorsal fin in males; three or four lateral mandibular neuromasts.................................................................... L. aureoguttatus

2b. Two dark-red stripes on anterior portion of dorsal and ventral submarginal parts of caudal fin in males; male caudal-fin stripes not branching posteriorly; dark-orange small spots on basal portion of dorsal fin in males; five or six lateral mandibular neuromasts................................................................... L. itanhaensis sp. nov.

3a. Dorsal-fin origin in vertical between base of seventh and ninth anal-fin rays; iris bright green in males.........4

3b. Dorsal-fin origin in vertical between base of second and sixth anal-fin rays; iris bright blue in males ............ 5

4a. Caudal fin elliptical; dark-red stripe on distal margins of dorsal and anal fins, and dorsal and ventral margin of caudal fin in males........................................................................................................... L. opalescens

4b. Caudal fin lanceolate; diffuse dark-reddish brown pigmentation on distal margins of dorsal and anal fins, and dorsal and ventral margin of caudal fin in males ................................................................ L. citrinipinnis

5a. Caudal fin asymmetrical, with convex dorsal outline and straight ventral profile; urogenital papilla attached to anal fin in males; anterior portion of anal fin with thickened tissue in males; caudal fin light blue with small dark-reddish brown spots, and white stripe with narrow black border on ventral edge of fin in males; flank dark brown with horizontal rows of yellow spots, coalesced to form stripe on the lateral midline of caudal peduncle in males .......................................................................................................................... L. marmoratus

5b. Caudal fin symmetrical, dorsal and ventral outlines convex; urogenital papilla free in males; no thickened tissue on anal fin; caudal fin red with light-blue vermiculate marks; flank red with zigzag-shaped bright-blue bars ...................................................................................................................................... L. splendens altitude of ~ 5 m a.s.l. [about 25°30′S, 48°25′W]; lectotype, MNRJ 28924 , designated herein ).

Material examined: Brazil, Estado do Paraná: MNRJ 28924, lectotype, male, 29.8-mm SL; MNRJ 19495, paralectotypes, two females; road between Paranaguá and Matinhos, Paraná, near km 11; CAS ( SU) 50191, 11; road east of Paranaguá; UFRJ 199, 7; temporary pool in forest, near km 5 of road between Paranaguá and the coast; UFRJ 6331, 14, UFRJ 6332, six (c&s); temporary pool in forest close to road PR-407, about 5 km from Praia de Leste, 25°40′42.1″S , 48°30′12.6″. Brazil, Estado de São Paulo: MNRJ 19480, seven paralectotypes; MNRJ 19451, 8 ; MNRJ 19473, six paralectotypes; MNRJ 19550, two paralectotypes; Registro, Ribeira de Iguape river floodplains; UFRJ 5212, 35; UFRJ 5213, ten (c&s); temporary pool in Sobradinho river floodplains, Iguape, about 24°45′S, 47°25′W .

Diagnosis: Distinguished from all congeners, except L. itanhaensis sp. nov., by having four caudal neuromasts (vs. two) and horizontal golden lines on caudal fin in males (vs. lacking that colour pattern). Differs from L. itanhaensis sp. nov. in having two dark-red stripes through the dorsal and ventral submarginal parts of the caudal fin in males, along entire length of caudal fin (vs. limited to anterior portion of fin), male caudal-fin stripes branching posteriorly (vs. not branching, parallel to fin rays), basal portion of dorsal fin with dark-red to dark-brown short transverse bars in males (vs. dark-orange small spots), three or four lateral mandibular neuromasts (vs. five or six), and 25–28 caudal-fin rays (vs. 27–31).

Description: Morphometric data appear in Table 1. Largest specimen: 29.8-mm SL. Dorsal profile: approximately straight to gently convex from snout to end of dorsal-fin base, approximately straight along caudal peduncle. Ventral profile: weakly convex from lower jaw to end of anal-fin base, approximately straight along caudal peduncle. Body: slender, deeper than wide, subcylindrical anteriorly, to compressed posteriorly. Greatest body depth found at vertical through pelvic-fin base. Jaws short, snout blunt.

Dorsal and anal fins: distally pointed in males. Dorsal fin slightly pointed, and anal fin rounded in females. Caudal fin: elliptical. Pectoral fin: elliptical, posterior margin reaching vertical through anus in males, and vertical between pelvic-fin base and anus in females. Tip of pelvic fin reaching vertical between urogenital papilla and base of first anal-fin ray in males, between anus and urogenital papilla in females. Pelvic-fin bases medially in contact. Dorsalfin origin: on vertical between base of fifth and sixth anal-fin rays. Urogenital papilla free of anal fin. Dorsal-fin rays, 14–16; anal-fin rays, 17–20; caudalfin rays, 25–28; pectoral-fin rays, 14–15; pelvic-fin rays, 5–6.

Scales: small, cycloid. Body and head entirely scaled, except anteroventral surface of head. Body scales extending over anterior 20–25% of caudal-fin base; scales absent on dorsal and anal-fin bases. Frontal squamation E-patterned; E-scales not overlapped; A-scale with posterior margin exposed. Longitudinal series of scales, 26–28; transverse series of scales, eight; scale rows around caudal peduncle, 12–14. Minute contact organs on posterior margin of scales of flank in males.

Cephalic neuromasts: supraorbital, 1 + 9–11; parietal, 1, anterior rostral, 1; posterior rostral, 1; infraorbital, 1–2 + 17–19; preorbital, 3–4; otic, 1–3; postotic, 2; supratemporal, 1; median opercular, 1; ventral opercular, 1–3; preopercular, 2 + 10–14; mandibular, 5–6 + 2; lateral mandibular, 3–4. One or two neuromasts on centre of each scale of lateral line. Four neuromasts on caudal-fin base.

Coloration: Males: sides of body dark-red crimson to orangish red, with longitudinal rows of small brightblue to golden spots, more concentrated on anterior half of flank. Dorsum: light-yellowish brown. Venter: pale red. Head: light-yellowish brown, opercle bright blue to golden with two red stripes with transverse extensions to form reticulated pattern. Lower jaw: red. Iris: bright green with oblique dark-red bar. Dorsal fin: yellow with dark-red to dark-brown short transverse bars on basal and posterior portions of fin. Basal portion of anal fin: yellow with dark-red spots, distal portion dark-orangish brown. Caudal fin with greenish golden lines on middle, to light golden on dorsal and ventral portions of fin; two dark-red stripes through dorsal and ventral submarginal part of fin; similar dark-red stripes on median portion of fin, usually slightly narrower than submarginal stripes, from caudal-fin base to posterior margin of fin, branching posteriorly. Pectoral fins: hyaline. Pelvic fins: dark red.

Females: trunk and head, light-yellowish brown; fins, hyaline; iris, yellow.

Distribution: Between Ribeira do Iguape river basin, São Paulo state, and isolated coastal basins draining into Paranaguá bay, Paraná state, Brazil, including nearby islands (Comprida, Cardoso, and Mel) ( Fig. 4 ).

Habitat and conservation: Leptolebias aureoguttatus inhabits shallow temporary pools within forests or swampy depressions on forest borders. The water is tea-coloured and acidic (pH 3.5–4.0). Aquatic vegetation is not present and the bottom is composed of litter, except in habitats on the forest border, where Poaceae , Typhaceae , and Cyperaceae are abundant. No other fishes were found. Still known in several localities, including well-preserved forests, it may be considered a vulnerable but not endangered species.

Figures

Figure 2. Frontal squamation and neuromast pattern in Leptolebias aureoguttatus. Abbreviations: A–H, frontal scales A–H; AIS, anterior infraorbital series; AN, anterior nostril; ARN, anterior rostral neuromast; ASN, anterior supraorbital neuromast; PAS, parietal series; PBS, preorbital series; PN, posterior nostril; PRN, posterior rostral neuromast; PSS, posterior supraorbital series. Scale bar: 1 mm.

Figure 3. Osteological features in Leptolebias and Notholebias: A, medial portion of hyoid and branchial skeleton, dorsal view, of Leptolebias citrinipinnis. B, medial portion of hyoid and branchial skeleton, dorsal view, of Notholebias fractifasciatus. C, anguloarticular region, left side, lateral view, of L. citrinipinnis. D, jaw suspensorium, left side, lateral view, of N. fractifasciatus. Abbreviations: AA, anguloarticular; B1–B3, basibranchials 1–3; BB, basibranchial cartilage; BC, basihyal cartilage; BH, basihyal; H1–H3, hypobranchials 1–3; HY, hyomandibula; MS, mesopterygoid; MT, metapterygoid; PL, autopalatine; PO, preopercle; QU, quadrate; RA, retroarticular; SY, sympletic. Larger stippling indicates cartilage. Scale bar: 1 mm.

Figure 4. Geographical distribution of Leptolebias in São Paulo and Paraná states, southern Brazil: L. aureoguttatus (•) and L. itanhaensis (Ɨ).

Figure 5. Geographical distribution of Leptolebias in Rio de Janeiro state, south-eastern Brazil: 1, L. marmoratus, L. splendens, and L. opalescens; 2, L. marmoratus and L. opalescens; 3, L. splendens; 4, L. citrinipinnis.