IUCN threat status:

Critically Endangered (CR)

Comprehensive Description

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Austrolebias cinereus (Amato)

(Fig. 12)

Cynolebias carvalhoi ZBK (non C. carvalhoi ZBK Myers, 1947); Vaz-Ferreira & Sierra, 1971: 30 (misidentification and description of specimens from arroyo de las Viboras , Colonia , Uruguay ).

Cynolebias cinereus ZBK Amato, 1986: 9 ( type locality: swamp in Ruta 21, 2 km NW of arroyo de Las Viboras , Colonia , Uruguay ; holotype : MUNHINA 2614 ).

Material examined

Uruguay : Colonia : UFRJ 6148 , 4; UFRJ 6149 , 8 (c&s); CTL 1262 , 18; arroyo de las Viboras floodplains near Ruta 21, rio de la Plata basin , 33°56.40’S58º22.16’W ; P. Laurino et al. , 12 Sep. 2004 . MNRJ uncat. , 1; same locality ; R. Vaz-Ferreira & B. Soriano , Sep. 1959 .

Diagnosis

Distinguished from all other species of the A. robustus group by the following combination of features: dorsal-fin origin on vertical through base of 3rd or 4th anal-fin rays in males, just anterior to anal-fin origin in females; scales in longitudinal series 29-31; vertebrae 28-30; flank dark gray in males; spots on flank and no large spot at end of caudal peduncle in females.

Description

Morphometric data appear in Table 2. Males larger than females, the largest male examined 48.0 mm SL, largest female 43.6 mm SL. Dorsal profile nearly straight to gently concave on head, convex from nape to end of dorsal-fin base, approximately straight on caudal peduncle; no distinctive adipose ridge on frontal region. 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 slightly deep and compressed. Snout blunt, jaws short.

Tip of both dorsal and anal fin rounded. Anteromedian rays of anal fin of females not lengthened; distal portion of anal fin thickened in females. Caudal fin rounded. Pectoral fin elliptical, posterior margin on vertical through base of 4th anal-fin ray in males, and through anus in females. Tip of each pelvic fin reaching between base of 2nd and 3rd anal-fin rays. Pelvic-fin bases medially united, and medial pelvic-fin margins not coalesced. Urogenital papilla not attached to anal fin. Dorsal-fin origin on vertical through base of 3rd or 4th anal-fin ray in males, slightly anterior to anal-fin origin in females; anal-fin origin through base of 2nd or 3rd dorsal-fin ray in females; dorsal-fin origin between neural spines of 8th and 9th vertebrae in males, between neural spines of 10th and 12th vertebrae in females. Anal-fin origin between pleural ribs of 8th and 9th vertebrae in males, between pleural ribs of 10th and 11th vertebrae in females. Dorsal-fin rays 22-25 in males, 18-22 in females; anal-fin rays 23-27 in male, 20-25 in females; caudal-fin rays 27-30; pectoralfin rays 12; pelvic-fin rays 4-5.

Scales large and cycloid. Trunk and head entirely scaled, except for ventral surface of head. Sometimes a few scales extending over anal-fin base; no scales on dorsal-fin base; three rows of scales on caudal-fin base. Frontal squamation F-patterned; E-scales not overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 29-31, scales regularly arranged; transverse series of scales 15; scale rows around caudal peduncle 22. One prominent contact organ on each scale over entire flank and on opercle in males. Rows of prominent contact organs on anal-fin rays; row of contact organs on four uppermost pectoral-fin rays in males. No contact organ on dorsal and caudal fins.

Cephalic neuromasts: supraorbital 20-23, parietal 2-3, anterior rostral 1, posterior rostral 1, infraorbital 3 + 23-25, preorbital 2, otic 4, post-otic 4-5, supratemporal 1, median opercular 1, ventral opercular 2-3, preopercular plus mandibular 42-44, lateral mandibular 5-6.

Basihyal subtriangular, width about 85 % of length; basihyal cartilage moderate, about 45 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Six teeth on second pharyngobranchial. Gill-rakers on first branchial arch 3 + 11. Dermosphenotic ossification absent. Ventral process of posttemporal long. Total vertebrae 28-30.

TABLE 2. Morphometric data of the Austrolebias robustus species group.

A. cinereus A. vazferreirai
males (5) females (5) males (11) females (8)
Standard length (mm) 41.3-48.0 33.0-43.6 48.7-80.8 37.5-64.7
Percents of standard length
Body depth 33.6-38.8 35.1-38.2 35.2-38.5 34.4-38.9
Caudal peduncle depth 14.4-17.8 13.5-16.7 14.9-17.4 14.0-16.3
Pre-dorsal length 50.7-53.1 57.1-62.9 50.4-55.3 56.7-63.2
Pre-pelvic length 44.1-46.2 52.9-57.0 44.8-49.6 52.8-56.6
Length of dorsal-fin base 39.8-42.7 28.0-34.2 36.9-45.5 29.1-33.8
Length of anal-fin base 39.4-43.2 24.0-27.2 38.7-43.4 23.3-32.2
Caudal-fin length 30.9-33.3 35.7-40.0 28.6-34.3 29.4-36.8
Pectoral-fin length 24.3-26.2 24.7-29.2 19.8-25.0 21.6-25.2
Pelvic-fin length 9.9-11.8 10.8-13.2 8.4-11.1 8.8-10.7
Head length 28.0-30.2 29.0-32.5 27.9-30.1 29.6-32.0
Percents of head length
Head depth 107.4-117.1 101.1-108.4 101.9-116.8 99.2-108.4
Head width 70.2-77.0 73.8-80.2 68.7-79.2 70.7-82.4
Snout length 15.7-17.5 15.0-16.9 15.2-17.4 15.0-18.7
Lower jaw length 22.4-24.6 19.8-22.3 19.4-25.3 19.3-24.5
Eye diameter 22.7-25.1 23.2-25.8 20.6-23.8 20.0-26.6
(continued).
A. robustus A. nonoiuliensis
males (7) females (7) males (3) females (3)
Standard length (mm) 44.2-53.0 39.7-53.1 44.1-49.6 34.8-42.6
Percents of standard length
Body depth 35.4-41.3 36.4-41.4 32.4-35.4 34.0-35.6
Caudal peduncle depth 14.2-16.2 14.8-15.9 14.3-16.3 14.5-14.9
Pre-dorsal length 53.7-56.9 56.9-60.6 53.7-57.6 59.7-61.8
Pre-pelvic length 46.5-50.8 50.8-54.2 43.8-45.6 50.6-53.9
Length of dorsal-fin base 34.0-40.2 29.2-37.1 36.6-38.1 28.3-32.9
Length of anal-fin base 35.9-39.3 27.7-30.0 36.8-42.4 26.1-31.2
Caudal-fin length 33.0-38.6 34.9-42.3 35.8-39.0 39.1-40.7
Pectoral-fin length 23.0-28.7 22.9-27.3 23.8-26.3 24.7-26.2
Pelvic-fin length 10.8-12.8 10.2-12.6 11.7-12.1 11.5-14.2
Head length 28.4-31.1 29.7-32.5 27.4-29.4 29.1-32.1
Percents of head length
Head depth 99.5-116.1 100.8-114.3 101.1-110.3 97.0-108.5
Head width 67.4-75.6 71.6-79.4 73.9-75.6 74.0-74.6
Snout length 14.3-16.6 13.5-16.7 14.2-16.3 14.7-16.2
Lower jaw length 22.6-26.3 20.0-24.2 22.4-23.3 20.9-23.1
Eye diameter 19.9-23.1 20.1-25.2 24.1-25.3 23.5-26.7

FIGURE 12. Austrolebias cinereus , UFRJ 6148, male, 46.9 mm SL, above, UFRJ 6148, female, 43.3 mm SL, below; Uruguay: Colonia: arroyo de las Viboras floodplains.

Coloration

Males: sides of body dark bluish gray to brown; juvenile with 9-10 narrow light brownish gray bars, rarely vestigial bars on caudal peduncle in adult. Urogenital papilla dark gray. Opercular and infraorbital regions dark bluish or greenish gray; approximately rectangular black infraorbital bar, subtriangular black supraorbital bar. Iris orangish brown, with dark brown bar through center of eye. Unpaired fins and pelvic fins dark bluish gray. Pectoral fins hyaline.

Females: sides of body light yellowish brown, with round to slightly vertically elongated dark gray spots, often darker on anterocentral portion of flank, sometimes black; no distinctive spot on caudal peduncle. Opercular region pale greenish golden. Iris orangish brown, with gray bar through center of eye. Infraorbital and supraorbital bars dark gray. Unpaired fins hyaline, with small dark gray to black spots; paired fins hyaline.

Distribution

Known only from arroyo de las Víboras floodplains, río de La Plata basin, Colonia, southwestern Uruguay (Fig. 8).

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Source: Plazi.org

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