Lebiasina ardilai, Netto-Ferreira, André L., Lopez-Fernandez, Hernán, Taphorn, Donald C. & Liverpool, Elford A., 2013

Netto-Ferreira, André L., Lopez-Fernandez, Hernán, Taphorn, Donald C. & Liverpool, Elford A., 2013, New species of Lebiasina (Ostariophysi: Characiformes: Lebiasinidae) from the upper Mazaruni River drainage, Guyana, Zootaxa 3652 (5), pp. 562-568 : 563-567

Lebiasina ardilai , new species

Figure 1 , Table 1

Lebiasina Géry & Zarske, 2002: 45 [Comparison with Lebiasina yepezi Netto-Ferreira et al., 2011 ]. Lebiasina sp. Géry & Zarske, 2002: 46 [Comparison with habits of Derhamia hoffmannorum ].

Holotype. UG/CSBD 1663 (Ex-ROM 83872), 114.2 mm SL, Guyana, Zone 7, Essequibo River system, Mazaruni River drainage Waruma Creek at campsite, 5°28'40.3"N 60°46'45.3"W, 20 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens, K. Kramer.

Paratypes. (196 specimens). All from Guyana, Zone 7, Essequibo River system, Mazaruni River drainage: AMNH 59036 (1, 79.7 mm SL), Arabaru River, 600 to 1200 m elev., tributary to Kako river, left-bank tributary of upper the Mazaruni River, 05°39'N 60°38'W, 31 Jan to 10 Feb 1939, A. S. Pinkus; BMNH 1976.6.18.5 (1, 86.1 mm SL), Kako, presented to M. Tamessar, 18 Jun 1976; ROM 83666 (1, 37.0 mm SL), Kukui River, sandy/driftwood shore, 5°30'50.8"N 60°24'45.9"W, 14 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens; ROM 83671 (1, 33.3 mm SL), Kukui River, 5°30'50.8"N 60°24'45.9"W, 15 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens; ROM 83681 (4, 27.49–30.74 mm SL), Kukui River, left hand at sandy beach, 5°23'55.0"N 60°25'4.6"W, 15 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens; ROM 83711 (1, 109.51 mm SL), Kukui River, upstream around the camp on Philipai, 5°21'37.1"N 60°22'18.4"W, 17 Apr 2008, H. López-Fernández, D.C. Taphorn E.A. Liverpool, K. Kramer, C. Thierens; ROM 83721 (55, 22.1– 46.7 mm SL), Kukui river, sandy beach on the right bank, 5°33'28.8"N 60°23'45.9"W, 17 Apr 2008, H. López- Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens; ROM 83732 (2, 27.9–33.9 mm SL), sandy beach at the confluence of the Mazaruni River and the Kukui River, 5°40'21.2"N 60°28'58.6"W, 17 Apr 2008, H. López- Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens, K. Kramer; ROM 83744 (1, 152.3 mm SL), sandy beach at the confluence of the Mazaruni River and the Kukui River, 5°40'21.2"N 60°28'58.6"W, 17 Apr 2008, H. López- Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens, K. Kramer; ROM 83754 (2, 31.1–52.0 mm SL); sandy beach and associated embayment both created by gold-mining dredging, 5°41'35.4"N 60°28'11.8"W, 18 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens; ROM 83763 (4, 25.8–30.8 mm SL), lower Kukui River at 1.5 km from the mouth, 5°39'11.5"N 60°28'12.3"W, 19 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool; ROM 83782 (6, 85.4–234.3 mm SL), Waruma Creek at campsite, 5°28'40.3"N 60°46'45.3"W, 20 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens, K. Kramer; ROM 83792 (2, 96.8–97.5 mm SL), Waruma Creek, tributary of Kako River, riffles and shallow rapids upstream from camp, 5°28'31.8"N 60°46'46.8"W, 20 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens; ROM 83805 (1, 103.0 mm SL), Waruma Creek, tributary of Kako River, downstream from camp at the complex of riffles and shallow, semi-isolated pools, 5°29'9.8"N 60°47'22.4"W, 21 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens, K. Kramer; ROM 83861 (35, 27.8–63.3 mm SL), Memboru creek at an artificial sandy beach, 5°55'34.0"N 60°35'26.8"W, 23 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool; ROM 83879 (9, 26.9–67.3 mm SL; 1, 61.0 mm SL CS), Beach on Mazaruni river downstream from Kamarang, 5°56'10.1"N 60°36'53.8"W, 24 Apr 2008, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, C. Thierens; ROM 89534 (2, 48.6–52.8 mm SL), river channel on right bank of Mazaruni River, downstream of confluence with Kukui River (Jawalla), tailings beach, 5°40'37.4"N 60°28'55.7"W, 0 6 Mar 2011, H. López-Fernández, D.C. Taphorn, E.A. Liverpool, S. Refvik, J. Enright, K. Kramer; ROM 89537 (2, 33.1–51.4 mm SL), beach on left bank of Kamarang River, just downstream from Kelly Kramer's house, 5°51'59.5"N 60°37'14.5"W, 14 Mar 2011, H. López- Fernández, S. Refvik, D.C. Taphorn, E.A. Liverpool, K. Kramer, G. Kramer; ROM 89557 (1, 49.8 mm SL), main channel on a mine tailings beach on Mazaruni River, just downstream from Abbou Creek on left bank, 5°42'30.5"N 60°21'39.6"W, 0 4 Mar 2011, D.C. Taphorn, E.A. Liverpool, H. López-Fernández, S. Refvik; ROM 89567 (1, 34.0 mm SL), pools in front of campsite at Waruma Creek, 11 Mar 2011, E.A. Liverpool, D.C. Taphorn, G. Kramer, J. Kelly; ROM 89665 (7, 31.8–44.1 mm SL), backwater channel on right bank of Mazaruni River, in front of Warwata village, near mouth of Kamarang River, 16 Mar 2011, H. López-Fernández, D.C. Taphorn, E.A. Liverpool; ROM 89670 (3, 42.4–54.2 mm SL), backwater channel on right bank of Mazaruni River, in front of Warwata village, near mouth of Kamarang River, 24 Mar 2011, H. López-Fernández, D.C. Taphorn, E.A. Liverpool; ROM 89677 (1, 103.2 mm SL), camp at Sanda Creek, Kako River basin, 5°34'6.2"N 60°48'34.1"W, 0 9 Mar 2011, H. López-Fernández; ROM 89686 (16, 37.3–106.6 mm SL), Sanda Creek, area above Wishek Falls, 5°34'52.7"N 60°48'31.1"W, 0 9 Mar 2011, H. López-Fernández; ROM 89729 (2, 123.2– 131.4 mm SL), Sanda Creek, 0 9 Mar 2011, H. López-Fernández; ROM 89736 (6, 46.1–76.7 mm SL), channel on left bank of Mazaruni River, downstream from Kamarang, 1 km upstream from Mamburi, 5°55'1.8"N 60°36'13.5"W, 13 Mar 2011, H. López-Fernández, D.C. Taphorn, E. Liverpool, S. Refvik, K. Kramer; ROM 93354 (1, 48.7 mm SL), Guyana, Zone 7, Essequibo River drainage, Kamarang River, 1.5 hrs upstream from Waramadong, 5°50'25.88"N 60°52'5.73"W, 0 3 Nov 2011, E.A. Liverpool; ROM 93391 (10, 24.6–46.0 mm SL), tailing-sandy beach at Mazaruni River, 1 hr downstream from Kamarang River mouth, 5°56'10.0"N 60°36'52.0"W, 0 5 Nov 2011, E.A. Liverpool; ROM 93402 (8, 33.0– 52.2 mm SL), Mazaruni River, upstream from site 9, 5°56'13.9"N 60°36'52.3"W, 0 5 Nov 2011, E.A. Liverpool; ROM 93417 (10, 31.9–43.8 mm SL), tailing-sandy beach at Mazaruni River, downstream from Kabrou, upstream from site 10, 5°56'8.5"N 60°36'43.4"W, 0 5 Nov 2011, E.A. Liverpool; ROM 93429 (1, 48.0 mm SL), Kabrou, Mazaruni River upstream from site 10, 5°28'34.5"N 60°46'42.7"W, 0 5 Nov 2011, E.A. Liverpool; ROM 93442 (1, 96.5 mm SL), rapids at Waruma Creek, 5°28'31.8"N 60°46'44.4"W, 0 6 Nov 2011, E.A. Liverpool

Diagnosis. Lebiasina ardilai is distinguished from all lebiasinins by its color pattern consisting of a narrow, nearly straight primary stripe, extending from posterior to humeral blotch to near the vertical through anal-fin origin, being nearly absent in females and conspicuously marked in males; the presence of four series of dark markings at the base of the scales of longitudinal series 2–5; the faint secondary stripe running onto scales of second and third longitudinal row of scales; and the posteriorly displaced caudal blotch, not reaching the posterior tip of caudal peduncle. The new species also differs from its Guyana Shield relatives L. taphorni Ardila-Rodríguez, L. unitaeniata (Günther), L. uruyensis Fernandez-Yépez , Lebiasina yepezi Netto-Ferreira et al. and L. yuruaniensis Ardila-Rodríguez by the lack of the intermediate stripe.

Description. Morphometric data of the holotype and paratypes are presented in Table 1 . Lateral view of holotype, and a female paratype in Fig. 1 (a and b, respectively). Body cylindrical, elongate. Greatest body depth anterior to dorsal-fin origin in the median distance between pectoral and pelvic fins. Dorsal profile of head convex from tip of upper lip to dorsal-fin origin, straight from latter point to base of dorsal fin, concave from that point to anteriormost dorsal caudal-fin procurrent ray. Ventral profile of head and trunk distinctly convex from tip of lower lip to anal-fin origin, concave from that point to origin of anteriormost ventral caudal-fin procurrent ray.

Mouth sub-superior. Premaxillary with single row of 13(1) tricuspid teeth. Maxillary with 5(1) tricuspid or conic teeth. Anteriormost tooth usually largest. Posterior terminus of maxilla reaching slightly beyond anterior margin of orbit. Dentary with two series of teeth; outer series with 15(1) pedunculate tricuspid teeth with central cusp distinctly longer than lateral ones, decreasing gradually in size posteriorly; inner series with several minute conical teeth extending from symphysis to coronoid process. Branchiostegal rays 4(10); three rays articulating with anterior ceratohyal and one with posterior ceratohyal.

Scales cycloid, circuli restricted to border of scales, several radii converging to center of scale and strongly anastomosed in focus, forming several cells. Lateral line series with 27(3), 28(1) or 29*(6) scales, of which only 5 (1) or 6*(9) perforated. Longitudinal rows of scales between dorsal and pelvic fins 7*(10). Predorsal scales 11(2), 12 (7) or 13*(1). First longitudinal row of scales usually extending beyond vertical through dorsal-fin terminus by one or two scales. Circumpeduncular scales 12*(10).

Pectoral-fin rays i,12(3), i,13*(6) or i,14(1). Tip of longest pectoral-fin ray falling far short of vertical through pelvic-fin insertion. Pelvic-fin rays i,7*(10). Supraneurals 11(1), anterior to neural spine of centra 5 to 14(1). Dorsal-fin rays iii,7(1) or 8*(7). First dorsal-fin pterygiophore inserting behind neural spine of centrum 14*(1). Distal margin of dorsal fin rounded. Dorsal-fin origin located closer to caudal-fin origin than to tip of snout. Base of last dorsal-fin ray situated distinctly anterior to vertical through anal-fin origin. Anal-fin rays iii,8*(10), with last ray adnate. Distal margin of extended anal fin rounded. First anal-fin pterygiophore inserted posterior to haemal arch of centrum 18(1). Adipose fin present. Caudal fin furcate with upper lobe slightly longer than lower lobe; both lobes rounded. Principal caudal-fin rays i, 9/i,8*(7) or i, 10/i,8(1). Dorsal caudal-fin procurrent rays 8(1); ventral caudal-fin procurrent rays 9(1). Precaudal vertebrae 23(1); caudal vertebrae 17(1).

Color in alcohol. Background color predominantly light brown. Head densely pigmented from upper lip to first scales overlying portion of parietal. Dark brown pigmentation extending from that point to insertion of caudal fin, along mid-dorsal series of scales and scale rows two and three. Maxilla, circumorbital bones and opercular series dark, becoming lighter ventrally. Lower lip densely pigmented. Ventral portion of head scarcely pigmentated. Opercular membrane with small scattered chromatophores.

Trunk dark dorsally, becoming lighter ventrally from second longitudinal series of scales. Abdominal region yellowish, with minute dark chromatophores from isthmus to anal-fin origin. Humeral blotch rounded; more conspicuous in juvenile and smaller adult specimens. Primary stripe present, being conspicuous only in males, inconspicuous or absent in females. Faint, inconspicuous secondary stripe passing onto scales of second and third longitudinal scale rows, more evident in specimens up to 90 mm SL. Four longitudinal series of dark markings at distal margin of scales of longitudinal series 2 to 5; dark markings never coalescing. Caudal blotch present, conspicuous, displaced posteriorly resulting in anterior border not extending onto caudal peduncle. Pectoral and pelvic fins mostly hyaline with medio-distal portion slightly pigmented. Branching point of rays on dorsal, anal and caudal fins variably pigmented. Adipose fin hyaline.

Color in life. Background coloration of body dark brown from dorsum to ventral portion of flanks. Body gradually lighter from longitudinal line near pectoral fin origin to ventral portion of body. Unpaired fins strongly pigmented, varying from orange to red; paired fins slightly orange. Eyes dark colored ranging from brown to dark red.

Sexual dimorphism. Mature male specimens of Lebiasina ardilai present the most common pattern of sexual dimorphism among species of the genus as described by Netto-Ferreira et al. (2011) and Netto-Ferreira (2012): longer and thicker anal-fin rays, with thickened intervening membranes; hypertrophied developed anal-fin rays erectors, inclinators and depressors muscles associated to larger points of insertion onto the pterygiophores; and breeding tubercles on the infraorbital bones, opercle and subopercle, lateral surface of pectoral- and pelvic- fin rays, posterior border of scales on the sides of the body and caudal-fin rays, with the remark that in L. ardilai , contrarily to other species, the contact organs on scales along the body are considerably more densely distributed. Lebiasina ardilai also presents a rather interesting sexual dimorphic pattern involving the primary stripe: in male specimens it is strongly marked ( Fig. 1 a), whereas in females the stripe varies from faint to absent ( Fig. 1 b). A similar condition is observed in L. unitaeniata and L. yuruaniensis , despite the fact that the primary stripe is always present in female representatives of these species, although less conspicuous than in males.

Distribution. Lebiasina ardilai is endemic to the upper Mazaruni River drainage and it is known from the Arabaru, Kukui, Membaru, Waruma and Mazaruni rivers ( Fig. 2 ).

Etymology. The specific epithet is in honor of Carlos Ardila Rodríguez for his numerous contributions to the systematics of the Lebiasininae . A noun.

Ecological notes. Lebiasina ardilai is a black water species ( pH 4.4–6.7, conductivity ranging between 0–10 µS), found in temperatures ranging from 21.6–24.0 ºC, and most frequently associated with relatively high concentrations of dissolved oxygen (3.8–9.3 mg /L) and high transparency 15–85 cm. The species is often found in relatively fast waters (0–0.51 m /s) at depths varying between 0.15–1.1 m in both small tributaries and the main channel of rivers. The species appears to be relatively tolerant of variation in the amount of riparian vegetation and the degree of human disturbance, being found both in pristine and highly impacted habitats.

Remarks. The secondary stripe extending along scales of second and third longitudinal series, and the caudalfin blotch restricted to the caudal-fin median rays observed in Lebiasina ardilai were regarded as putative synapomorphic conditions grouping the Guyana Shield species by Netto-Ferreira et al. (2011). Those authors also proposed the presence of the intermediate stripe as a synapomorphic condition for that putative group. The absence of such stripe in specimens of L. ardilai suggests either a more basal position of the new species within that group or a secondary loss of this feature. The sexually dimorphic expression of the primary stripe described herein as well as the presence of dark markings on the distal margin of scales of longitudinal series 2–5 in Lebiasina ardilai are features shared with Lebiasina unitaeniata and L. yuruaniensis , and seem to represent evidence toward a closer relationship among those species. Although dark blotches are also observed in Lebiasina marilynae , L. melanoguttata and L. minuta , these contrast with the observed in L. ardilai , L. unitaeniata and L. yuruaniensis in being distributed at the base of scales, instead of at their distal border.

Figures

FIGURE 1. Lebiasina ardilai, new species: (a) holotype, UG / CSBD 1663, 114.2 mm SL, male; (b) paratype ROM 83872, 113.0 mm SL, female, both from Guyana, Zone 7, Essequibo River system, Mazaruni River drainage Waruma Creek at campsite, 5 ° 28 ' 40.3 " N 60 ° 46 ' 45.3 " W.

FIGURE 2. Map of Northeastern South America, depicting the Mazaruni river drainage and adjoining areas, with distribution of L. ardilai (triangles) and putative: Lebiasina yuruaniensis (circles) and L. unitaeniata (diamonds). White polygons represent type-localities.

Tables

TABLE 1. Morphometric data of Lebiasina ardilai, new species. n = number of specimens; SD = standard deviation.

	Holotype	n range	mean	SD
Standard length	114.2	10 61.0 – 124.3	95.1
Percentage of SL
Depth dorsal-fin origin	24.1	10 21.6 – 26.5	23.7	1.3
Snout to anal-fin origin	74.2	10 74.0 – 77.8	75.8	1.3
Snout to pelvic-fin origin	50.2	10 49.8 – 52.1	51.2	0.8
Snout to dorsal-fin origin	54.0	10 52.6 – 56.6	55.0	1.3
Dorsal-fin origin to caudal base	47.8	10 44.2 – 48.5	47.0	1.2
Dorsal-fin length	19.3	10 16.9 – 21.8	19.8	1.4
Dorsal-fin base	9.8	10 7.9 – 10.6	9.4	0.8
Adipose to caudal-fin origin	13.8	10 12.2 – 14.7	13.2	0.7
Caudal-peduncle length	16.0	10 14.4 – 17.6	16.4	0.9
Caudal-peduncle depth	12.0	10 10.7 – 12.3	11.5	0.6
Anal-fin length	21.5	10 18.1 – 23.4	20.0	1.5
Anal-fin base	13.5	10 10.4 – 13.8	11.8	1.2
Pelvic- to anal-fin origin	25.7	10 23.7 – 27.4	25.8	1.4
Pelvic-fin length	14.7	10 12.6 – 15.7	14.3	1.0
Pectoral- to pelvic-fin origin	28.4	10 27.7 – 30.7	29.1	0.9
Pectoral-fin length	16.5	10 15.8 – 18.6	17.0	1.1
Snout to pectoral-fin origin	21.8	10 21.8 – 24.5	23.1	0.9
Bony head length	24.3	10 23.9 – 26.0	24.8	0.8
Percentage of HL
Head width	53.4	10 48.8 – 56.9	52.8	2.7
Horizontal eye diameter	21.0	10 20.3 – 27.0	22.9	2.3
Distance snout tip to eye	29.7	10 26.9 – 29.7	28.6	1.1
Interorbital distance	35.6	10 34.9 – 38.9	36.0	1.4
Length of lower jaw	45.8	10 42.8 – 46.3	45.3	1.0
Length of maxilla	38.3	10 34.8 – 39.6	37.6	1.6