Lethenteron ninae, Naseka, Alexander M., Tuniyev, Sako B. & Renaud, Claude B., 2009

Naseka, Alexander M., Tuniyev, Sako B. & Renaud, Claude B., 2009, Lethenteron ninae, a new nonparasitic lamprey species from the north-eastern Black Sea basin (Petromyzontiformes: Petromyzontidae), Zootaxa 2198 (1), pp. 16-26 : 18-25

publication ID	https://doi.org/ 10.11646/zootaxa.2198.1.2
persistent identifier	https://treatment.plazi.org/id/CF308783-7860-EF23-469F-FDD889433598
treatment provided by	Felipe
scientific name	Lethenteron ninae
status	sp. nov.

Treatment

Lethenteron ninae , sp. n.

( Figs. 2 View FIGURE 2 , 3a View FIGURE 3 , 4a View FIGURE 4 , 5 View FIGURE 5 , 6 View FIGURE 6 , 7a View FIGURE 7 , 8)

Holotype. ZISP 54431 View Materials (adult female, TL 163.8 mm; 43°48’35’’N 39°36’54’’E, Shakhe River at Khartsyz , Black Sea basin, Sochi District, Russia; coll. S.B. Tuniyev, 27 Sept. 2007). GoogleMaps

Paratypes. ZISP 54432 View Materials (2 adults, TL 145.1–158.7 mm, same data as for holotype) GoogleMaps ; ZISP 54433 View Materials (adult female, TL 166.0 mm, 43°34’21’’N 40°00’38’’E, Mzymta River at Kazachiy Brod , Black Sea basin, Sochi District, Russia; coll. S.B. Tuniyev, 20 Sept. 2006) GoogleMaps ; ZISP 54434 View Materials (4 adults, TL 131.7–163.7 mm, 4 ammocoetes, TL 90.0–120.0 mm, 43°26’26’’N 40°01’30’’E, Chakhtsutsyr Stream at Gumariya , Psou River basin, Black Sea basin, Sochi District, Russia; coll. S.B. Tuniyev, 17–24 Dec. 2006) GoogleMaps ; CMNFI 2008-0059 (1 adult, TL 149.5 mm, same data as ZISP 54434) GoogleMaps ; ZISP 54435 View Materials (4 adults, TL 130.6–162.5 mm; 2 ammocoetes, TL 99.6–104.5 mm; 42º45'36"N 41º27'59"E, Mokva River , Black Sea basin, Abkhazia, Georgia; coll. S.B. Tuniyev, 24 Sept. 2007) GoogleMaps ; ZISP 54436 View Materials (6 ammocoetes, TL 124.1– 141.8 mm, 43°39’01’’N 40°04’27’’E, Mzymta River in Adler , Black Sea basin, Sochi District, Russia; coll. S.B. Tuniyev, 14 Jan. 2008) GoogleMaps .

Non-type material: SNP 23 (ammocoete, TL 120.6 mm, Shakhe River, Black Sea basin, Sochi District, Russia; coll. B.S. Tuniyev, 7 May 1986); SNP 65 (ammocoete, TL 141.5 mm, Mzymta River, Black Sea basin, Sochi District, Russia; coll. A.M. Naseka , J. Freyhof, V.A. Drogan, 11 July 2001); ZISP uncat. (5 ammocoetes, TL 128.0–148.0 mm, 42º45'36"N 41º27'59"E, Mokva River, Black Sea basin, Abkhazia, Georgia; coll. A.M. Naseka , N.G. Bogutskaya , S.B. Tuniyev, A.N. Ivanitskiy, 30 July 2007); ZISP uncat. (ammocoete, TL 140.6 mm, 43º11'38"N 40º17'38"E, Bzyb' River at village of Alakhodzy, Black Sea basin, Abkhazia, Georgia; coll. A.M. Naseka , N.G. Bogutskaya , S.B. Tuniyev, A.N. Ivanitskiy, 2 Aug. 2007).

Diagnosis. Lethenteron ninae is distinguished from the other species of Lampetrinae in Europe and West Asia (Black Sea basin) by possessing the following character states: adults with a dark blotch near the apex of the second dorsal fin; exolaterals absent; posterials present in one incomplete row (i.e., a toothless gap in the middle) or occasionally absent; transverse lingual lamina with 9–15 unicuspid teeth, the median one markedly enlarged; supraoral lamina with two unicuspid teeth separated by a toothless bridge; 1–2 rows of anterials, usually 2; first row of anterials with 5–7 unicuspid teeth; oral fimbriae, 69–99; trunk myomeres in both ammocoetes and adults, 56–62; in ammocoetes, trunk not mottled, cheek and upper prebranchial area extensively pigmented (≥ 75% coverage) and tongue precursor bulb clearly triangular, with wide base and pointed apex bearing few cirri.

Description. Ammocoetes ( Fig. 2 View FIGURE 2 , Table 2). The maximum size found in our material was 148 mm TL. However, we expect that ammocoetes attain a length larger than 166 mm TL as the adults reach this length. Trunk myomeres were 56–60 ( Table 2). The bulb of the tongue precursor is clearly triangular, with a wide base and a pointed apex bearing few cirri ( Fig. 7a View FIGURE 7 ). Ammocoetes (live and freshly preserved specimens) are grey along the back with lighter undersides without mottling ( Fig. 2 View FIGURE 2 ). External pigmentation is generally well developed. In most specimens the pigmentation coverage of the upper lip, cheek, upper prebranchial and upper branchial areas is about 75% or more ( Fig. 2 View FIGURE 2 ; Table 2).

Other areas have either slight (1% to <25%) pigmentation coverage (caudal fin) or are unpigmented (lower branchial and ventral branchial) ( Table 2). Internally, the pigmentation coverage of the areas lateral to the elastic ridge is slight and it is absent on the tongue precursor bulb ( Fig. 7a View FIGURE 7 ). Lateral line neuromasts are unpigmented. The caudal fin shape is either spade-like or rounded ( Fig. 2 View FIGURE 2 ).

Adults ( Figs. 5-6 View FIGURE 5 View FIGURE 6 , Tables 1–2). We do not describe here morphometric data of the new species and do not compare it with other species because our material includes only recently metamorphosed adults while type material of E. mariae and L. lanceolata comprise only spawning and spent individuals collected in the spring. It is known that natural shrinkage occurs in lampreys not only when they go through metamorphosis but also when adults become sexually mature, and therefore, only adults at a given stage of development may be compared. The oral disc is shown in Fig. 3a View FIGURE 3 . The transverse lingual lamina has 9–15 unicuspid teeth (9 teeth in the holotype), the median one markedly enlarged ( Fig. 4a View FIGURE 4 ). Longitudinal lingual laminae are straight, each with 5–9 unicuspid teeth (not seen in the holotype). The supraoral lamina has two unicuspid teeth separated by a toothless bridge. The infraoral lamina has 7 unicuspid teeth (in four specimens including holotype), 5 unicuspid 1 bicuspid (2), 1 bicuspid 5 unicuspid (2), 1 bicuspid 3 unicuspid 1 bicuspid (2) and three other formulae also found in one specimen each. Three endolaterals occur on both sides of the oral disc, all bicuspid (including in the holotype) in most specimens, but the middle or bottom endolateral is sometimes tricuspid. There are 1–2 rows of anterials, usually 2 (1 in the holotype). The first row of anterials has 5–7 (5 in four specimens, 6 in two specimens and 7 in two specimens, including holotype) unicuspid teeth. Exolaterals are absent in all specimens. Posterials are absent (in three specimens) or first and only row of posterials incomplete with 1–5 unicuspid, rarely bicuspid, teeth on each side (two unicuspid – toothless gap – two unicuspid in holotype). There are 7 velar tentacles (in two specimens dissected; Fig. 8), the median one is shorter than the adjacent lateral ones and the tentacles have tubercles on the dorsal aspect. There are no wings. Number of trunk myomeres is 58–62 (58 in holotype). The number of myomeres to the origin of first dorsal fin is 31–36 (34 in holotype). The number of myomeres to the end of the first dorsal fin is 44–50 (47 in holotype). The number of oral fimbriae is 69–99 (93 in holotype; 74–90 in most specimens). The caudal-fin shape is spade-like ( Fig. 5 View FIGURE 5 ) or rounded ( Fig. 6 View FIGURE 6 ). Coloration of live and freshly preserved recently metamorphosed adults is not mottled; it is greyish with the back darker than the belly. The caudal fin is slightly (1% to <25% coverage) to moderately (25% to <75% coverage) pigmented, almost hyaline in some specimens ( Fig. 5 View FIGURE 5 ). There is a dark blotch near the apex of the second dorsal fin ( Figs. 5 View FIGURE 5 and 6 View FIGURE 6 ). The lateral-line neuromasts are darkly pigmented on the ventral surface ( Fig. 3a View FIGURE 3 ) and in the prebranchial region ( Figs. 5 View FIGURE 5 and 6 View FIGURE 6 ) in some individuals and unpigmented in others.

Distribution. Lethenteron ninae is known from rivers of the Black Sea coast in Russia and Abkhazia ( Fig. 9 View FIGURE 9 ) (from west to east): Psezuapse, Shakhe, Mzymta, Psou (Chakhtsutsyr Stream), Bzyb’, Mokva ( Tuniyev 1999; Drogan 2002; Bogutskaya & Naseka 2004 ; Tuniyev 2005, 2006, 2008; data published herein). Berg (1948) reports ammocoetes from near Novorossiysk that he assigns to E. mariae , but these may belong to L. ninae . A lamprey is also known from Mchishta and Kodori rivers and Bebesyr Lake in Abkhazia ( Barach 1960; Elanidze 1983) and from Inguri and Makhindzhauri rivers and rivulets near Batumi further east in Georgia ( De Filippi 1865; Kokotshashwili 1942; Barach 1960; Elanidze 1983) but its identification needs to be established.

Habitat and biology. Ammocoetes are found in silt, sand or fine pebble sediment in sections with slow or no current, usually in the middle and low reaches of rivers ( Fig. 10 View FIGURE 10 ), often in shallows at banks or backwaters at depths of about 10–50 cm, among submerged plants ( Rumex acetosella, Polygonum sp., Juncus sp. , Poaceae ). In general, the abundance is relatively low, 1–8 (averaging 2) individuals per 100 m 2, but in some localities in the Psou and Mzymta rivers there were up to 400 individuals of all sizes per 100 m 2.

Adults and ammocoetes are commonly caught together. First post-metamorphosis individuals are found in the second half of September in the Mzymta and Shakhe rivers and those in the Psou River (Chakhtsutsyr Stream) in the second half of December. Ammocoetes caught in the Mokva River in September and kept in aquarium started metamorphosis at the end of November and completed it by the middle of December.

Etymology. The new species is named after Nina Bogutskaya in appreciation of her contribution to the knowledge of Eurasian freshwater fishes. It is treated as a noun in the genitive case. Common name: Western Transcaucasian brook lamprey.

Comparisons. The new species was assigned to the genus Lethenteron because it possesses the diagnostic characters of this genus, namely, the absence of exolaterals and the usual presence of a single albeit incomplete row of posterials. In western Eurasia, the latter character is shared by L. ninae and L. zanandreai , which was known from the Po River drainage and the adjacent Adige River basin of northern Italy, but is now considered to have scattered populations along the Adriatic coast from central Italy to Bosnia-Herzegovina ( Kottelat & Freyhof 2007). Lethenteron ninae differs from L. zanandreai by having 56–62 trunk myomeres (vs. 52–60) in both ammocoetes and adults, and a dark blotch on the second dorsal fin of the adults (vs. no blotch). From geographically proximate E. mariae , it differs by the presence of dark blotch on second dorsal fin in adults (vs. no blotch), the absence of exolaterals (vs. 1–4 rows of exolaterals, see Fig. 3b View FIGURE 3 ), 1–2 rows of anterials with the first row having 5–7 teeth (vs. 3–5 rows, first row with 5–10 teeth), transverse lingual lamina with 9–15 well developed teeth, the median one markedly enlarged (vs. 3–7 teeth, see Figs. 3b View FIGURE 3 , 4b View FIGURE 4 ), caudal fin usually slightly pigmented or hyaline (vs. moderately to usually extensively pigmented), 56–62 trunk myomeres in both ammocoetes and adults (vs. 62– 73), tongue precursor bulb triangular with pointed apex bearing few cirri in ammocoetes ( Fig. 7a View FIGURE 7 ) (vs. bulbous with widened apex bearing numerous cirri, Fig. 7b View FIGURE 7 ), upper lip, cheek, upper prebranchial and upper branchial areas in ammocoetes commonly extensively pigmented ( Fig. 2 View FIGURE 2 , Table 3) (vs. non-pigmented to slightly pigmented, Table 2) and live and freshly-preserved (1–3 yrs) ammocoetes not mottled (vs. mottled; this character taken from Holčík (1986)). As to comparison with L. lanceolata from the Black Sea basin in north-eastern Turkey, we could examine only one adult paratype of this species ( Table 3) and three topotypic ammocoetes ( Table 2). The paratype of L. lanceolata has no exolaterals and only one very small posterial tooth on the far right side, and thus belongs to Lampetra . Lethenteron ninae differs from Lampetra lanceolata by having a single incomplete row of 3–7 posterials (the row is rarely absent), 9–15 cusps on the transverse lingual lamina with the median one markedly enlarged (vs. one enlarged median cusp with no adjacent lateral cusps), 5–7 teeth in the first row of anterials (vs. 9), 69–99 oral fimbriae (vs. about 124) and the cheek and upper prebranchial area extensively pigmented in ammocoetes ( Fig. 2 View FIGURE 2 ) (vs. unpigmented).

Comparative material. Eudontomyzon mariae: ZISP 23124 (26 syntypes: spawning adults, TL 157–198 mm; Severskiy Donets River near Khar’kov, Don River drainage, Black Sea basin, Ukraine; 24 April – 5 May 1930) ; CMNFI 1986-0718 (6 syntypes: spawning adults, TL 171–183.5 mm; same data as ZISP 23124) ; ZISP 29159 View Materials (2 adults, TL 137–171 mm, 4 ammocoetes, TL 55–167 mm; Severskiy Donets River , Don River drainage, Black Sea basin, Ukraine; 1923-1930) .

Lampetra lanceolata: CMNFI 1986 -0913 (paratype: spent female, TL 124 mm; mouth of Iyidere River near Trabzon, Black Sea basin, Turkey; 20 April 1969); CMNFI 1986–0914 (3 ammocoetes, TL 84–143 mm; Iyidere River , near Trabzon, Black Sea basin, Turkey; June 1971) .