Austrolebias nachtigalli, Wilson J. E. M. Costa, 2006

Wilson J. E. M. Costa, 2006, The South American annual killifish genus Austrolebias (Teleostei: Cyprinodontiformes: Rivulidae): phylogenetic relationships, descriptive morphology and taxonomic revision., Zootaxa 1213, pp. 1-162 : 133-136

Austrolebias nachtigalli Costa & Cheffe, new species

(Fig. 50)

Austrolebias nigrofasciatus non Costa & Cheffe; Costa & Cheffe, 2001: 188 (misidentification of specimens from arroio Grande and rio Jaguarão drainages).

Material examined

Holotype. UFRJ 6183 , male, 43.5 mm SL; Brazil: Rio Grande do Sul: Arroio Grande, road BR-116 , about 32°15’S 53°5’W; W. J. E. M. Costa & A. C. Bacellar, 8 Sep. 1999.

Paratypes. Brazil: Rio Grande do Sul: UFRJ 5245 , 1 male, 40.3 mm SL, 1 female, 33.4 mm SL; UFRJ 5010 , 4 males, 37.9-41.8 mm SL, 12 females, 31.4-39.3 mm SL; UFRJ 5011 , 2 males, 36.7-38.5 mm SL, 2 females, 29.5-36.7 mm SL (c&s); Arroio Grande, road BR-116 ; W. J. E. M. Costa & A. C. Bacellar, 8 Sep. 1999. UFRJ 4992 , 4 males, 26.6-34.7 mm SL, 6 females, 24.1-30.2 mm SL; ditch at road side, between Arroio Grande and lagoa Mirim ; W. J. E. M. Costa & A. C. Bacellar, 8 Sep. 1999. UFRJ 4991 , 5 males, 22.4-35.6 mm SL, 23 females, 22.4-37.3 mm SL; temporary pool at km 11 of the road Arroio Grande-lagoa Mirim ; W. J. E. M. Costa & A. C. Bacellar, 8 Sep. 1999. UFRJ 6184 , 3 males, 32.0-42.6 mm SL, 1 female, 35.9 mm SL; temporary pool close to arroio Grande, 10 km E of the road BR-116 ; W. J. E. M. Costa, M. I. Landim & C. Moreira, 19 Jul. 1997. CIMC 3558 , 20 males, 22.0-30.4 mm SL, 33 females, 23.9-32.9 mm SL; temporary swamp at Passo do Salso, Arroio Grande ; M. Cheffe & G. N. Mauricio, 29 Nov. 2000. CIMC 8628 , 5 males, 30.0-33.5 mm SL, 10 females, 25.3-30.6 mm SL; UFRJ 6185 , 1 male, 29.6 mm SL, 1 female, 29.5 mm SL; UFRJ 6186 , 2 males, 22.0-30.4 mm SL, 3 females, 27.9-29.0 mm SL; rua 27 de novembro, between the second and third bridge, about 10 km from the road BR-116, Jaguarao ; L. E. K. Lanés, M. V. Volcan, B. Klotzel & G. M. Wallwitz, 5 Sep. 2004.

Additional material (non types). UFRJ 4206 , 98; temporary pool close to arroio Grande, 10 km E of the road BR-116 ; W. J. E. M. Costa, M. I. Landim & C. Moreira, 19 Jul. 1997. UFRJ 4178 , 13; temporary pool close to arroio Grande, 26 km E of the road BR- 116 ; W. J. E. M. Costa, M. I. Landim & C. Moreira, 19 Jul. 1997. UFRJ 4177 , 69; temporary swamp 12 km NE of Jaguarao , road BR-116 ; W. J. E. M. Costa, M. I. Landim & C. Moreira, 19 Jul. 1997.

Diagnosis

Distinguished from A. charrua , A. minuano , and A. adloffi by having a broad black bar on the posterior portion of the dorsal and anal fins (vs. black bar absent) and light blue bars on dorsal fin in males (vs. dots or elongate spots); from A. charrua by a distinctive black bar on parietal series of neuromasts; from A. adloffi by fewer anal-fin rays (21-26 in males and 19-22 in females, vs. 26-30 in males and 23-26 in females); from A. minuano by lesser maximum body depth in older males (42.6 % SL vs. 51.2 % SL) and fewer teeth on second pharyngobranchial in larger specimens (3-4 vs. 6-7); from A. nigrofasciatus by the dorsal-fin origin posterior to the anal-fin origin in males (vs. anterior or slightly posterior) and the absence of light blue bars on the anal fin in males (vs. presence); and from A. salviai by a shorter snout (12.6-15.3 % HL, vs. 16.4-18.6 % HL), wider head (66.6-71.4 % HL, vs. 61.4-66.6 % HL), and flank bars slightly narrower or as wide as interspace (vs. bars much narrower).

Description

Morphometric data appear in Table 9. Males larger than females, largest male examined 43.5 mm SL, largest female 36.9 mm SL. Dorsal profile straight to slightly concave on head, convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle; often adipose ridge on frontal region of head in males. Ventral profile convex from lower jaw to end of anal-fin base, nearly straight on caudal peduncle. Greatest body depth at level of pelvic-fin base. Body deep and compressed. Snout blunt and jaws short.

Tip of both dorsal and anal fins rounded. Anteromedian rays of anal fin of females lengthened, anal fin shape nearly triangular; distal portion of anal fin thickened in females. Caudal fin rounded. Pectoral fins elliptical, posterior margin on vertical between base of 3rd and 7th anal-fin rays in males, and between anus and urogenital papilla in females. Tip of each pelvic fin reaching base of 2nd or 3rd anal-fin ray. Medial pelvic-fin membranes 10 -40 % coalesced. Urogenital papilla not attached to anal fin. Dorsal-fin origin on vertical between base of 2nd and 4th anal-fin rays in males; dorsal-fin origin anterior to anal-fin origin in females, anal-fin origin through base of 1st or 2nd anal-fin ray; dorsal-fin origin between neural spines of 8th and 10th vertebrae in males, between neural spines of 10th and 11th vertebrae in females. Anal-fin origin between pleural ribs of 8th and 10th vertebrae in males, between pleural ribs of 10th and 11th vertebrae in females. Dorsal-fin rays 19-23 in males, 15-19 in females; anal-fin rays 21-26 in males, 19-22 in females; caudal-fin rays 21-24; pectoral-fin rays 11-12; pelvic-fin rays 5-6.

Scales large and cycloid. Trunk and head entirely scaled, except ventral surface of head. One row of scales on anal-fin base, no scales on dorsal-fin base, and three rows of scales on caudal-fin base. Frontal squamation usually H or G-patterned, sometimes F- patterned; E-scales slightly overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 26-28, scales regularly arranged; transverse series of scales 11-14; scale rows around caudal peduncle 16. Three to seven minute contact organs on each scale of ventral portion of flank in male. Rows of minute contact organs on three uppermost pectoral-fin rays, sometimes minute contact organs on distal portion of anteriormost anal-fin rays in males. No contact organ on dorsal and caudal fins.

Cephalic neuromasts: supraorbital 17-21, parietal 2-4, anterior rostral 1, posterior rostral 1, infraorbital 1-2 + 25-26, preorbital 2-3, otic 2-5, post-otic 3-6, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 21-23, mandibular 11-17, lateral mandibular 4-8.

Basihyal nearly triangular, width about 50-80 % of length; basihyal cartilage long, about 55-70 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Three or four teeth on second pharyngobranchial. Gill-rakers on first branchial arch 3-4 + 9-10. Dermosphenotic ossification absent. Ventral process of posttemporal variable, usually short or absent, sometimes long. Total vertebrae 27-29.

Coloration

Males: sides of body metallic blue, with 8-12 dark brown to black bars, anterior bars darker and narrower, about half interspace width or slightly wider, posterior bars as wide as interspace; sometimes an 8-shaped black spot on posterior part of caudal peduncle. Urogenital papilla gray. Sides of head light blue on opercular and infraorbital region; black infraorbital bar, wider close eye, gradually narrowing ventrally, often tip posteriorly directed in larger specimens; elongate black supraorbital bar, with distinctive narrow extension over neuromast parietal series. Iris dark yellow, with dark brown bar through center of eye. Dorsal fin dark bluish gray, with short blue bars on basal portion reaching median portion of fin, and transverse series of elongated light blues spots on middle of fin; broad dark gray to black bar with anterior bright blue border on posterior portion of fin; distal half of fin with golden to pink iridescence. Anal fin dark bluish gray, with small triangular spots on fin base and broad dark gray to black bar on posterior portion of fin; distal half of fin with blue iridescence. Caudal fin dark bluish gray, with light blue iridescence and faint elongated blue spots on dorsobasal portion. Pelvic fins dark bluish gray. Pectoral fins hyaline with bluish black ventral margin.

Females: sides of body light yellowish brown, with vertical rows of elongate gray spots, sometimes forming gray bars; venter pale golden; no black spot on anterocentral portion of flanks; usually two black spots vertically arranged on posterior portion of caudal peduncle, often coalesced to form an 8-shaped spot, which is occasionally absent. Opercular region pale blue. Iris light yellow, with gray bar through center of eye. Infraorbital and supraorbital bars gray. Unpaired fins gray, with light gray bars on basal portion of dorsal and anal fins, sometimes large dark gray blotch on posterior portion of dorsal and anal fins; paired fins hyaline, sometimes faint gray stripe on ventral margin of pectoral fins.

Distribution

River drainages associated with inner margin of the lagoa Mirim, laguna dos Patos system, Rio Grande do Sul, southern Brazil (Fig. 52).

Etymology

Named in honor of the ornithologist Giovani Nachtigall Mauricio, in appreciation of his valuable efforts to collect annual fishes from Rio Grande do Sul.