Tetragonopterus georgiae ( Géry, 1965 ) Gery, 1965

Silva, Gabriel S. C., Melo, Bruno F., Oliveira, Claudio & Benine, Ricardo C., 2016, Revision of the South American genus Tetragonopterus Cuvier, 1816 (Teleostei: Characidae) with description of four new species, Zootaxa 4200 (1), pp. 1-46 : 19-22

Tetragonopterus georgiae ( Géry, 1965) , new combination

( Fig. 5 , Table 4 )

Moenkhausia georgiae Géry, 1965: 104 (original description; type locality: “between ‘Saut-Chien’ and ‘Saut-Topi-Topi’, middle Mana River, French Guyana); Géry, 1977: 443 (in key to the genus Moenkhausia ). Vari et al., 2009: 32 (listed; Guiana shield); Mol et al., 2012: 270 (listed; Suriname). Melo et al., 2016: 709 –717 (molecular phylogeny).

Diagnosis. Tetragonopterus georgiae is distinguished from all congeners, except T. rarus , by having 4.5–5.5 scale rows between lateral line and pelvic fin origin (vs. 3.5 scale rows). It can be diagnosed from T. rarus by the absence of longitudinal dark stripes on the trunk (vs. the presence of stripes). Tetragonopterus georgiae differs from T. anostomus , T. denticulatus , T. kuluene and T. juruena by having 4 principal teeth in dentary (vs. 5–6) and by having larger and more robust teeth (vs. thinner and sharper teeth). Tetragonopterus georgiae differs from T. anostomus and T. kuluene by the presence of two conspicuous humeral marks (vs. only one inconspicuous humeral mark); it also differs from T. anostomus by having a terminal mouth (vs. subsuperior mouth). Tetragonopterus georgiae differs from T. anostomus and T. araguaiensis by the presence of 10–12 gill rakers on the upper limb (vs. 17–20) and 7–8 gill rakers on the lower limb (vs. 10–12) of the first gill arch. Tetragonopterus georgiae also differs from T. argenteus by the presence of 8 predorsal scales (vs. 11–17), and from T. carvalhoi by the presence of a rounded dark mark on the caudal peduncle (vs. a lozenge-shaped dark mark). Tetragonopterus georgiae differs from T. ommatus by having 1–4 teeth on maxilla (vs. 7–8) and by having a dark mark centered on caudal peduncle (vs. mark limited to the posterior portion of the caudal peduncle).

Description. Morphometric data summarized in Table 4 . Body shape compressed and deep. Greatest body depth at dorsal-fin origin. Dorsal profile slightly convex between tip of snout and vertical through middle of orbit; slightly concave from this point to end of occipital process; convex from tip of occipital process to dorsal-fin origin; then slightly convex between dorsal-fin origin and rear of adipose fin. Prepelvic region transversely flattened with distinct, longitudinally aligned lateral keels. Ventral profile of body slightly convex from lower lip to slightly behind vertical through pectoral-fin origin; convex from that point to anal-fin origin; straight along base of anal fin. Caudal peduncle with dorsal and ventral profiles slightly concaves.

Olfactory lamellae 20 (3), 22 (2), 23 (1), 24 (1) or 25 (3). Mouth terminal. Upper and lower jaws of similar size. Premaxilla in two rows of relatively robust teeth. Outer row with 4 (7), 5 (9) or 6 (1) teeth with three cusps, central cusps longest. Inner row with 5 (14) or 6 (1) teeth with three or five cusps, central cusps twice as long as the lateral cusps. Maxilla with 2 (7) or 3 (8) either conic or tricuspidate teeth. Dentary bearing 4 (16) or 5 (1) anteriormost teeth with 3 to 5 cusps.

Dorsal-fin rays ii,9 (18). First unbranched ray shorter than second one. Dorsal-fin origin anterior to middle of body in SL. Anal-fin rays iv,23 (6), iv,25 (4), iv,26 (6) or iv,27 (1); posterior unbranched rays and anterior branched rays slightly longer than following rays. Anal-fin origin situated posterior to vertical line through posterior most branched dorsal-fin rays. Pelvic-fin rays i,7 (18); origin situated anterior to vertical line through dorsal-fin origin; tip of adpressed pelvic fin reaching first unbranched anal-fin ray. Pectoral-fin rays i,11 (1) i,12 (1), i,13 (10), i,14 (3) or i,15 (2). Caudal fin forked.

Scales large and cycloid. Lateral line complete and slightly bent downward anteriorly. Longitudinal scales 31 (5), 32 (8), 33 (4) or 34 (2). Scale rows between lateral line and dorsal-fin origin 6 (17) or 7 (1). Scale rows between lateral line and pelvic-fin origin 4.5 (18). Predorsal scales 7 to 9. Scale rows around caudal peduncle 13 (3) or 14 (15). Anal-fin base covered by a single row of small scales. Caudal-fin base covered by small scales in both lobes; such scales smaller than those covering lateral surface of body.

First gill arch with 7 (3), 8 (13) or 9 (1) gill rakers on upper limb and 11 (4), 12 (11) or 13 (1) gill rakers on lower limb. Total vertebrae 29, precaudal vertebrae 12, intermediate vertebrae 2 and caudal vertebrae 17 (3 c&s). Supraneurals 3 (2 c&s).

Color in alcohol. General body color yellowish. Dorsal portions of head and body darkly pigmented. Dorsolateral portion of body with few minute chromatophores along distal margin of scales; scales of ventrolateral portion of body unpigmented. Opercular and infraorbital bones silvery. Two conspicuous vertical dark humeral marks separated by one scale, with anterior mark more evident. Anterior humeral mark extending over four horizontal scale rows above and one horizontal scale rows below lateral line. Posterior humeral mark located over three horizontal scales rows above lateral line. Caudal peduncle with a distinctly rounded dark mark. Midlateral silvery stripe broad, extending from supracleithrum to caudal peduncle. Anal, pelvic, and dorsal fins hyaline, with chromatophores concentrated at distal portions of the rays. Adipose fin hyaline covered by small chromatophores distally ( Fig. 5 a).

Sexual dimorphism. None observed.

Distribution. Tetragonopterus georgiae is known from Siparuni, Rupununi and Potaro rivers of the Essequibo basin in Guyana; Río Nichare, Orinoco basin in Venezuela and the upper Rio Paru, a left tributary of the Amazon basin in northern Brazil. Vari et al. (2009) reported Moenkhausia georgiae (= T. georgiae ) in French Guyana and Suriname. Mol et al. (2012) listed M. georgiae for the Corantijn, Nickerie, Coppename, Suriname, and Marowijne River basins of Suriname. Le Bail et al. (2012) reported M. georgiae for the Mana, Sinnamary, Comté, Orapu, Approuague, and Oyapock rivers of French Guyana at the boundary with Amapá in Brazil. We herein recorded T. georgiae for Venezuela at the Río Cuyuni (a tributary of Essequibo River) and Río Nichare (a tributary of Río Caura), the latter record extending the distribution of the species to the Río Orinoco basin. We also recorded T. georgiae in the upper Rio Paru, a left-margin tributary of the rio Amazonas with headwaters at the Guiana Shield ( Fig. 2 a).

Remarks. Eigenmann’s (1917) definition of Moenkhausia is based on the presence of two parallel rows of premaxillary teeth, five or more teeth in the inner premaxillary tooth row, a completely pored lateral line, and the presence of scales covering the lobes of the caudal fin. Although Moenkhausia and Tetragonopterus are phenotypically similar in body shape, the later usually has a downward curved lateral line along with other apomorphic characters ( Mirande 2010; Melo et al. 2011). Géry (1965) described M. georgiae and allocated it in Moenkhausia due to the non-proeminent curvature of the anterior portion of the lateral line. Later, Géry (1977) cited M. georgiae as “a species strongly resembling Tetragonopterus chalceus . Four examined paratypes (ANSP 94708, ANSP 112246, ANSP 139714) ( Fig. 5 a-b) have three supraneurals and a branched laterosensory canal in the sixth infraorbital, synapomorphies previously proposed for Tetragonopterus ( Melo et al. 2011) . The later authors discuss that such features are not present in any other species of Moenkhausia (including its type species, M. xinguensis ), except M. georgiae . A molecular phylogeny of the genus Tetragonopterus placed M. georgiae as the sister to all Tetragonopterus species ( Melo et al. 2016). Thus, M. georgiae is herein formally transferred to Tetragonopterus .

Material examined: Types: ANSP 94708, 1 paratype, 57.9 mm SL, Suriname /French Guyana, upper Marowijne, Tampoc (into Litany rivier), J. Géry, 29 Nov 1957 . ANSP 112246, 1 paratype, 33.7 mm SL, ANSP 139714, 2 paratypes, 35.9–48.4 mm SL, French Guyana, Marowijne basin, middle Mana River , between Saut- Chien and Saut-Topi-Topi, J. Géry , 15 Oct 1957. Non-types: Venezuela: ANSP 168083, 39 , 20.5–50.8 mm SL , Bolivar, Cuyuni basin, Rio Hacha. MZUSP 77808, 3 , 34.6–40.9 mm SL , Bolivar, Rio Nichare. Guyana: ANSP 177000 , not measured , Essequibo basin, Siparuni river , 4°44’41”N 59°00’18”W . ANSP 190828, 16 , not measured, Rupununi region, upper Essequibo, Yukanopito falls . ANSP 190465, 4 , 35.3–41.5 mm SL, Rupununi region, Essequibo basin, Kuyuwini river . ANSP 190525, 7 , 31.2–56.2 mm SL, Rupununi region , Essequibo river, Kassi-Atae rapids . Suriname: ANSP 189638, 3 , 38.4–44.3 mm SL ; ANSP 189639, 3 , 38.4–44.3 mm SL; Marowijne basin , Sipaliwini, Anapaike, Lawa river . USNM 229604, 3 , 37–61.9 mm SL , Brokopondo , Marowijne river, 63 km Z. Van Afobaka. Brazil: LBP 21093, 1, 26.4 mm SL , Amapá, Oiapoque, Rio Oyapock, Igarapé Pantanari , 3°48’47.6”N 51°48’31.6”W . MZUSP 16758, 18 , 50.4–68.0 mm SL, Pará, Alto Paru d’Oeste, Amazon basin, upper Rio Paru .

Figures

FIGURE 5. Tetragonopterus georgiae. (a – b) Moenkhausia georgiae, ANSP 94708, paratype, 58.3 mm SL, French Guyana, Litany river, upper Marowijne river basin; c) T. georgiae, Suriname, live specimen. Photos (a – b) by K. Luckenbill and (c) by R. Covain.

Tables

TABLE 4. Morphometric data for Tetragonopterus georgiae (n = 22). Range includes paratypes.

	Range	Mean
Standard length (mm)	33.7–68.0	56.8
Percentages of standard length
Greatest depth	44.7–53.4	48.5
Predorsal length	49.7–53.3	51.4
Prepectoral length	25.5–29.6	27.2
Prepelvic length	45.8–54.8	51.1
Preanal length	64.1–70.8	67.6
Caudal peduncle depth	9.5–11.7	10.9
Caudal peduncle length	6.5–11.7	1.32
Pectoral-fin length	22.1–26.0	24.6
Pelvic-fin length	17.5–20.0	18.9
Dorsal-fin length	31.4–39.9	35.3
Length of dorsal-fin base	15.5–18.0	16.8
Anal-fin length	18.1–22.6	20.1
Length of anal-fin base	30.4–34.0	32.4
Distance from eye to dorsal-fin origin	40.1–48.9	46.6
Distance from dorsal-fin origin to caudal-fin base	54.6–60.4	57.4
Head length	26.5–29.8	28.0
Head depth	22.5–20.7	24.8
Percentages of head length
Snout length	13–22	16.4
Maxillary length	38–46	41.4
Horizontal orbital diameter	47–57	50.8
Least interorbital width	27–32	30.6