Austrolebias pelotapes COSTA & MOREVY, 2017

Costa, Wilson, Cheffe, Morevy & Amorim, Pedro, 2017, Two new seasonal killifishes of the Austrolebias adloffi group from the Lagoa dos Patos basin, southern Brazil (Cyprinodontiformes: Aplocheilidae), Vertebrate Zoology 67 (2), pp. 139-149 : 141-144

Austrolebias pelotapes COSTA & MOREVY sp. nov.

Fig 2 – 3 , Table 1

Holotype: UFRJ 8601 , male, 31.0 mm SL; Brazil: Estado do Rio Grande do Sul: Município de Pelotas: temporary pool in the Sanga Funda drainage, tributary of Arroio Pelotas , 31°43′46″S 52°19′07″W; L. LANÉS et al., 5 Nov. 2005 .

Paratypes: All from Município de Pelotas, Estado do Rio Grande do Sul, southern Brazil: UFRJ 8600 , 5 males, 25.9– 31.4 mm SL, 5 females, 22.8– 36.9 mm SL; collected with holotype . – UFRJ 8599 , 2 males, 23.7 – 26.4 mm SL, 4 females, 27.3 – 37.5 mm SL ; CIMC 8578 , 1 male, 34.6 mm SL, 1 female, 34.4 mm SL; swamp close to Arroio Pelotas, near Cotuvelo bridge; L. LANÉS et al., 19 Sep. 2004 . – UFRJ 8597 , 7 males, 19.7 – 26.4 mm SL, 3 females, 22.4 – 23.6 mm SL ; CIMC 8590 , 2 males, 22.8– 24.5 mm SL ; UFRJ 8598 , 3 males, 24.6 – 26.6 mm SL, 3 females, 20.7 – 23.8 mm SL (C&S); temporary pool at the end of the Plácido de Castro street, Sanga da Barbuda drainage, tributary of Arroio Santa Bárbara, Lindóia , 31°42′29″S 52°21′40″W, M. CHEFFE et al., 24 Sep. 2004 . – CIMC 13668 , 2 males, 27.5 – 31.4 mm SL, 2 females, 24.0– 24.5 mm SL (C&S); same locality as UFRJ 8599 ; M. CHEFFE & F. SILVEIRA, 14 Oct. 2004 . – UFRJ 8800 , 1 male, 23.4 mm SL, 1 female, 24.0 mm SL (DNA); same locality as UFRJ 8599; M. VOLCAN & A.C. GONÇALVES, 6 Jul. 2011 . – CIMC 17345 , 10 males, 20.3– 29.2 mm SL, 12 females, 21.5– 30.4 mm SL; temporary pool near Ildefonso Simões Lopes avenue, Sanga Funda drainage, tributary of Arroio Pelotas , 31°42′47″S 52°18′04″W; L. LANÉS & M. VOLCAN, 4 Oct. 2010 . – UFRJ 8885 , 3 males, 18.1 – 27.2 mm SL, 3 females, 19.4– 21.9 mm SL (DNA); same locality as CIMC 17345; M. VOLCAN & A.C. GONÇALVES, 6 Jul. 2011 .

Austrolebias pelotapes

UFRJ 8800.1 · Pelotas · KJ475078 31º 42′ 29″S 52º 21′ 39″W

UFRJ 8800.2 · Pelotas · KJ475079 31º 42′ 29″S 52º 21′ 39″W

UFRJ 8885.1 · Pelotas · KJ475080 31º 42′ 46″S 52º 18′ 02″W

UFRJ 8885.2 · Pelotas · KJ475081 31º 42′ 46″S 52º 18′ 02″W

UFRJ 8885.3 · Pelotas · KJ475082 31º 42′ 46″S 52º 18′ 02″W

UFRJ 8885.4 · Pelotas · KJ475083 31º 42′ 46″S 52º 18′ 02″W

Diagnosis. Austrolebias pelotapes is distinguished from all other species of the A. adloffi group by having the urogenital papilla base attached by a thin membrane to the anterior margin of the anal fin in males (vs. urogenital papilla free). Austrolebias pelotapes also seems to be the smallest species of the A. adloffi group, not reaching 35 mm SL (vs. maximum adult size between 43 and 45 mm SL). It is distinguished from all other species of the A. adloffi group except A. pongondo , by the following combination of character states: a transverse row of small spots on the middle portion of the dorsal fin in males (vs. transverse row absent in all other species), unpaired fins with a single row of light blue spots on their basal portion in males, and with distinctive dark grey zone on the posterior portion of the dorsal and anal fins (vs. multiple rows of blue dots and distinctive dark grey zone absent in A. charrua and A. minuano ), and caudal peduncle in males predominantly dark brownish grey or dark grey to black, with narrow vertical light blue zones in males (vs. alternating dark grey and light blue bars, dark grey bars slightly wider, equal or narrower than light blue bars, in A. adloffi , A. nachtigalli , A. nigrofasciatus , A. reicherti ). Austrolebias pelotapes is distinguished from A. pongondo by the former having 14 – 19 neuromasts in the supraorbital series (vs. 20 – 21) and 22 – 23 neuromasts around orbit (vs. 24 – 27); also useful to distinguish them are details of the colour pattern in live males, including the grey bars on the flank barely contrasting with the light blue colour ground (vs. dark grey to black bars in deep contrast to light blue interspace in A. pongondo ) and absence of a row of blue dots on the basal portion of the caudal fin (vs. presence).

Austrolebias pelotapes is also distinguished from all other species of the A. adloffi group by five unique nucleotide substitutions: cytb.219( A > G), cytb.243( T > C), cytb.480( T > C), cytb.501( G > A), cytb.663( C > T); it is similar to A. pongondo and distinguished from all other congeners of the A. adloffi group by four unique nucleotide substitutions: cytb.357( T > C), cytb.393( C > T), cytb.580( A > G), cytb.660( C > T); it is also distinguished from A. pongondo by the latter having six unique nucleotide substitutions: cytb.568( G > T), cytb.581( T > G), cytb.641( A > G), cytb.643( G > A), cytb.648( T > C), cytb.750( G > C). Other nucleotide loci useful to distinguish A. pelotapes from A. pongondo are: cytb.165( C), cytb.258( A), cytb.345( G), cytb.408( A), cytb.569( C) (vs. cytb.165( T), cytb.258( G), cytb.345( A), cytb.408( G), cytb.569( T) in A. pongondo ).

Description. Morphometric data appear in Table 1 . Largest male examined 34.6 mm SL; largest female examined 34.4 mm SL. Dorsal and ventral profiles convex from snout to end of dorsal and anal-fin bases, nearly straight on caudal peduncle. Body deep and compressed, greatest body depth at vertical through pelvic-fin base. Jaws short, snout blunt. Urogenital papilla cylindrical and short in males, its base attached to anal fin, tip free; urogenital papilla pocket-shaped in females, overlapping anal-fin origin.

Extremity of dorsal and anal fins rounded in both sexes. In females, anal fin sub-triangular with antero-median rays lengthened, distal portion thickened. Caudal fin rounded. Pectoral fin elliptical, posterior margin reaching vertical between base of 4 th and 7 th anal-fin rays in males, between urogenital papilla and anal-fin origin in females. Pelvic fin small, tip reaching base of 3 rd anal-fin ray; medial membrane about 30 – 60 % coalesced. Dorsal-fin origin on vertical between base of 3 rd and 5 th anal-fin rays in males, between base of 1 st and 2 nd rays in females; second proximal radial of dorsal fin between neural spines of 7 th and 9 th vertebrae in males, between neural spines of 8 th and 10 th vertebrae in females; first proximal radial of anal fin between pleural ribs of 7 th and 9 th vertebrae in males, between pleural ribs of 8 th and 10 th vertebrae in females. Dorsal-fin rays 21 – 23 in males, 17– 20 in females; anal-fin rays 23 – 26 in males, 20– 23 in females; caudal-fin rays 20 – 22; pectoral-fin rays 11 – 12; pelvic-fin rays 5 – 6.

Scales large, cycloid. Trunk and head entirely scaled, except on infraorbital region and ventral surface of head. Body squamation extending over anterior 20 % of caudal-fin base; one irregular row of scale on middle portion of anal-fin base, no scales on dorsal-fin base. Frontal scales irregularly arranged; E-scales slightly overlapping medially. One supra-orbital scale. Longitudinal series of scales 27 – 29; transverse series of scales 12; scale rows around caudal peduncle 16. One to three minute contact organs on each scale of antero-ventral part of flank in males; minute contact organs on internal surface of three uppermost pectoral-fin rays in males; no contact organs on unpaired and pelvic fins.

Cephalic neuromasts: supraorbital 14 – 19, parietal 3, anterior rostral 1, posterior rostral 1, infraorbital 2 + 22 – 23, preorbital 2 – 3, otic 3, post-otic 3 – 4, supratemporal 1, median opercular 1, ventral opercular 2 – 3, preopercular plus mandibular 36 – 39, lateral mandibular 6 – 8, paramandibular 1. One neuromast per scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal sub-triangular, basihyal cartilage about 40% of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 3 – 6. Gill-rakers on first branchial arch 3 + 10. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal well-developed. Total vertebrae 27 – 29.

Colouration. Males. Flank usually with 7 – 9 grey bars, separated by light blue interspace; anterior bars darker and narrower, slightly wider than adjacent light blue interspaces, posterior bars 2 – 4 times wider than adjacent light blue bars ( Fig. 3 ); in some specimens above 29 mm SL, flank bars increasing to 9 – 12 bars as result of ontogenetically appearing narrow light blue bars on middle of posterior wider grey bars ( Fig. 2 ). Urogenital papilla grey. Side of head intense blue on opercular and infra-orbital region; black infra-orbital bar, wider close eye, gradually narrowing ventrally; elongate black supraorbital bar, with distinctive narrow extension over neuromast parietal series. Iris dark yellow, with dark black bar through centre of eye. Dorsal fin dark bluish grey, darker near fin base; few light blue dots and short bars on basal half of fin; transverse sub-basal row of light blue dots. Anal fin bluish grey, basal half with light blue dots and narrow diffusing bars, distal half intense blue; black blotch, more visible in preserved specimens, on posterior portion of dorsal and anal fins, anteriorly limited by narrow oblique light blue bar. Caudal fin intense blue to dark bluish grey on dorsal portion; sometimes light blue dot on middle of fin base. Pelvic fin intense blue. Pectoral fin hyaline with black ventral margin.

Females. Flank light brownish grey; grey marks variable in form, ranging from spots vertically elongated to bars, marks sometimes absent; venter silver; no black spot on anterocentral portion of flank; two black spots vertically arranged on posterior portion of caudal peduncle, often coalesced to form 8-shaped spot, sometimes absent. Opercular region pale blue to pale golden. Iris light yellow, with grey bar through centre of eye. Infraorbital and supraorbital bars grey. Unpaired fins hyaline, with faint grey bars on basal portion of dorsal and anal fins; paired fins hyaline.

Genetic distance. To A. pongondo : 2.7– 3.6%; to A. nigrofasciatus : 8.2 – 8.4%; to A. adloffi : 4.5 – 5.3 %; to other species of the A. adloffi species group: 13.5 – 16.7%; intraspecific: 0 – 0.2.

Distribution and habitat. Austrolebias pelotapes is known from temporary pools and swamps associated to small streams tributaries to the northern margin of the Canal de São Gonçalo, Patos-Mirim lagoon system, Rio Grande do Sul, Brazil ( Fig. 3 ). In the type locality, water samples revealed the parameters: pH 6.4– 6.8, dissolved oxygen 5.7– 8.7 mg /l, and water temperature 16.7 – 25.9°C. Intensive field studies in the last 10 years have shown that all populations of this species are situated within or adjacent to urban areas of the town of Pelotas, in aquatic habitats being drastically reduced, making the species severely threatened with extinction. Given the small area of occurrence and the strong decline of habitats, A. pelotapes should be considered as a critically endangered species.

Etymology. The name pelotapes is the old usage for the town of Pelotas, from the Spanish pelota (ball), referring to a little boat made in cow hide, and tapes, referring to the indigenous tribe inhabiting the area occupied in the past by the new species.

Figures

Fig. 2. Austrolebias pelotapes: UFRJ 8601, holotype, male, 31.0 mm SL; Brazil: Rio Grande do Sul: Pelotas.

Fig. 3. Austrolebias pelotapes, topotype, male, not preserved (photograph by Matheus V. Volcan).

Tables

Table 1. Morphometric data of Austrolebias pelotapes.

	holotype	paratypes
	male	males (5)	females (6)
Standard length (mm)	31.0	26.3– 31.4	22.8– 29.4
Percent of standard length
Body depth	44.5	39.4– 45.3	38.7– 44.4
Caudal peduncle depth	17.3	15.1– 16.3	13.3– 15.2
Pre-dorsal length	53.0	53.3– 55.6	57.3– 63.0
Pre-pelvic length	49.2	45.6– 53.1	53.9– 60.7
Length of dorsal-fin base	42.3	36.2– 41.8	26.4– 34.7
Length of anal-fin base	47.5	43.5– 46.9	30.4– 36.1
Caudal-fin length	32.1	30.4– 35.1	33.8– 42.1
Pectoral-fin length	23.9	22.6– 30.3	23.9– 32.2
Pelvic-fin length	10.3	8.2–11.8	10.9– 15.1
Head length	31.8	30.2– 33.4	30.9– 34.2
Percent of head length
Head depth	117	101– 119	102– 109
Head width	65	60 – 64	68 – 72
Snout length	14	14 – 16	13 – 17
Lower jaw length	21	17 – 22	17 – 20
Eye diameter	28	26 – 30	28 – 32