Bathyaethiops flammeus, Moritz, Timo & Schliewen, Ulrich K., 2016

Moritz, Timo & Schliewen, Ulrich K., 2016, Description of two new Bathyaethiops species (Teleostei: Alestidae) from the Congo basin, Zootaxa 4117 (4), pp. 476-490 : 482-487

Bathyaethiops flammeus , new species

Red-back Moon Tetra

( Figs. 6–8 , Tables 3–4 )

Type material. Holotype: ZSM 43945, 39.1 mm SL, female; Democratic Republic of Congo, Province Orientale: Bakéré river at Yambula-Bakere (N 01°42’41’’, E 23°43’24’’); coll: U. Schliewen, J. Schwarzer & P.B. Mongindo, 19.07.2009.

Paratypes (n=22): ZSM 39295, 13 specimens, 24.5–39.9 mm SL, same data as holotype; AMNH 265018, 3 specimens, 29.4–32.3 mm SL, same data as holotype; DMM IE/9790, 2 specimens, 29.9–31.8 mm SL, same data as holotype; DMM IE/9791, 1 c&s, 34.1 mm SL, same data as holotype; MRAC B5-023-P-0001-0003, 3 specimens, 30.5–36.3 mm SL, same data as holotype.

Additional material. MRAC 177882–889, 8 specimens, 26.7-42.3 mm SL; Democratic Republic of Congo, Boende (S 0°14’, E 20°50’); coll. P. Brichard, 1969; ZSM A- 0649, 3 specimens, 25.2–27.8 mm SL; Democratic Republic of Congo, Ruki River (= lower Tshuapa River), Eala (close to Mbandaka); coll. Dr. Kiss, 17.11.1981.

Differential diagnosis. Distinguished from all congeners by the presence of a spot lacking melanophores (red in life, white in preservation), located in front of the dorsal fin.

Description. Based on holotype and 22 paratypes augmented with data from 11 non-type specimens. For general appearance refer to Figs. 5–7 . Measurements are summarized in Tables 3–4 for type and non-type specimens. Body laterally compressed, moderately elevated, maximum size 42 mm SL. Dorsal fin originating at midbody; pelvic fins originating slightly in front of dorsal fin; anal fin originating at level of, or slightly caudal to, end of dorsal-fin base. Scale cover complete; lateral line usually incomplete, but complete in a few specimens; when incomplete, number of pored scales in anterior section variable, 5–16 (5–14 on type locality); sometimes pored scales also present posteriorly after an interruption of varying extent. 7–10 pre-dorsal scales, but without scales immediately in front of dorsal-fin origin.

Premaxilla with two teeth in outer row, first with tree and second with five cusps, and four teeth in inner row with four to five cusps on first, seven cusps on second and third and five cusps on last tooth ( Fig. 9 ). Dentary with four teeth in outer row with seven cusps on second, six cusps on first and third, and four cusps on last tooth; an inner single monocuspid tooth close to symphysis present ( Fig. 9 ). Anal fin enlarged and convex in mature males, more or less straight in females and juveniles. Pectoral fin with 11–12 rays; pelvic fin with 9 rays. 2 hypurals in lower lobe and 4 hypurals in upper lobe; 3 epurals; small cartilage present in front of anterior-most haemal spine. Other fin and vertebrae counts presented in Table 4 . Supraneural directly in front of the first dorsal pterygiophore well developed or sometimes completely absent (well developed in all specimens from Boende and Eala).

Coloration. In life ( Fig. 7 ) body silvery, slightly translucent; anterior half of dorsal fin and the melanophorefree area in front of dorsal fin bright red; rest of dorsal fin, adipose fin and caudal fin grey; pectoral, pelvic and anal fin transparent; anterior distal part of anal fin black marked in males; upper half of adipose fin black in most specimens. A prominent dark humeral spot smaller than pupil and an extensive black blotch on the caudal peduncle; the latter is bisected by a dark line along the horizontal septum starting slightly behind humeral spot and continuing to the end of the caudal peduncle (this line is faint on the caudal peduncle of specimens from Boende); about 9 (7–9 in Boende, 10 in Eala) more or less regular vertical bars along the horizontal line with most bars located dorsally from the level of midbody. A dark line from the lower jaw over along the mid-dorsal line on the back to the end of caudal peduncle dark, with a prominent spot free of any melanophores in front of dorsal-fin base; base of anal fin darkly pigmented, more prominent anteriorly; a prominent dark bar on the end of the caudal peduncle broadened medially (less expressed in specimens from Boende and Eala); distal edge of adipose fin often black or dark grey, rest of fin slightly grey or colourless (black edge in all specimens from Boende; colourless in all specimens from Eala). Melanophores densely set on upper half of skull. Data on life coloration of specimens from Boende and Eala unavailable.

Yambula-Bakéré Boenđe Eala

Merisitic character Holotype Paratypes (N=22) (N=8) (N=3) In preservative ( Fig. 6 , 8 ) pale yellow to brownish, all prominent red coloration vanished; the melanophore free spot in front of the dorsal fin appears clear white; upper half of flank darker. Melanophore pattern less pronounced, but better visible as in life specimens; black mid-dorsal line less prominent; black mark along anal-fin base well visible in anterior part as in posterior part, where it is sometimes missing; this line (in contrast to life) not confluent with blotch on caudal peduncle.

Etymology. From the Latin flammeus for bright red or burning, referring to the bright red spot on nape in front of dorsal fin. An adjective.

Distribution and habitat. Type locality: Bakéré River at Yambula-Bakéré, Province Orientale, Democratic Republic of Congo ( Fig. 4 ), a large blackwater rainforest stream with no aquatic vegetation and sandy soil northwest of Kisangani directly entering the Congo River. Additional specimens were collected in 1969 in the Tshuapa River at Boende, and 1981 from the Ruki River (the name of the lower Tshuapa River after it has united with the Momboyo River) at Eala, both in the Democratic Republic of Congo. For these collections no additional data is available.

Remark. The specimens collected at Boende are clearly distinguishable from the type series, e.g., by scale counts. However, because the three specimens from Eala appear somewhat intermediate, e.g. in having 33–34 scales in supposed lateral line (vs. 33–36 in Yambula-Bakéré and 36–41 in Boende) 7.5 scales between lateral line and dorsal fin (vs. 6.5 in Yambula-Bakéré and 7.5–8.5 in Boende) and 14–16 scales around caudal peduncle (vs. 12 in Yambula-Bakéré and 13–18 in Bakéré), we conservatively interpret these differences as geographical variation and consider these geographically disparate populations as conspecifics rather than being separate species.

Figures

FIGURE 4. Records of Bathyaethiops species; filled symbols—localities where specimens where checked by Mamoneke & Stiassny (2012) or in the present study; symbol outlines—other records from MRAC database; T—type localities; star— B. atercrinis, cross— B. baka, circle— B. caudomaculatus, inverse triangle— B. flammeus, triangle— B. greeni,, square— B. breuseghemi.

FIGURE 5. Ngoko River between Nki falls and Ndongo (approx. N 02 ° 04 ’ 23 ’’, E 14 ° 49 ’ 52 ’’); Cameroon.

FIGURE 6. Bathyaethiops flammeus sp. nov., holotype, ZSM 43945; 39.1 mm SL.

FIGURE 7. Bathyaethiops flammeus sp. nov., live female directly after capture (05. August 2009) at Yambula-Bakéré, Democratic Republic of Congo.

FIGURE 8. Bathyaethiops flammeus MRAC 177882 - 889, specimen number 3; 36.9 mm SL, from Boende, Democratic Republic of Congo.

FIGURE 9. Dentition of Bathyaethiops flammeus sp. nov., paratype, DMM IE / 9791, 34.1 mm SL. A—single teeth in distal view. B—jaws in occlusal view.

Tables

TABLE 4. Meristic characters of Bathyaethiops flammeus n. sp., from đifferent localities. - = đamageđ, no count possible.

Simple đorsal-fin rays Brancheđ đorsal-fin rays	2 8	2 (22) 7 (1); 8 (21)	2 (7); 3(1) 8 (8)	2 (3) 8 (3)
Simple anal-fin rays Brancheđ anal-fin rays Upper procurrent cauđal-fin rays	3 22 11	3 (22) 21 (6); 22 (10); 23 (5); 24 (1) 7 (1); 8 (1); 9 (5); 10 (10); 11 (4); 12 (1)	3 (8) 21 (1); 23 (7) 8 (5); 9 (3)	3 (2); 4(1) 23 (2); 24 (1) 8 (1); 10 (1); 11(1)
Upper principal cauđal-fin rays Lower principal cauđal-fin rays	10 9	10 (21); 11 (1) 8 (1); 9 (21)	10 (8); 9 (8)	10 (3); 9 (3)
Lower procurrent cauđal-fin rays Vertebrae Abđominal vertebrae	8 37 16	6 (1); 7 (3); 8 (13); 9 (4); 10 (1) 36 (8); 37 (13); 38 (3) 16 (21); 17 (1)	7 (6); 8 (2) 35 (2); 36 (2); 37 (4) 16 (8)	7 (2); 8 (1) 36 (1); 37 (2) 16 (1); 17(2)
Cauđal vertebrae Dorsal fin inserting after vertebra Anal fin inserting after vertebra	21 9 17	20 (6); 21 (12); 22 (4) 8 (1); 9 (20); 10 (1) 16 (1); 17 (17); 18 (4)	19 (2); 20 (2); 21 (4) 9 (8) 15 (1); 16 (2); 17 (5)	19 (1); 20 (1); 21 (1) 8(1); 9 (1) 17 (3)
Supraneurals Scales along (supposeđ) lateral line (LL) Poređ scales in LL Scale rows between LL anđ đorsal fin	6 33 28 6.5	5 (7); 6 (14); 7 (1) 33 (3); 34 (6); 35 (9); 36 (4) 5 (1); 7 (1); 8 (4); 9 (2); 10 (3); 11 (5); 12 (2); 13 (2); 14 (1); 32 (1) 5.5 (2); 6.5 (20)	5 (1); 6 (7) 36 (1); 37 (2); 39 (2); 42 (1); 43 (1); - (1) 8 (1); 13 (2); 14 (1); 16 (1); 41 (1); - (2) 7.5 (1); 8.5 (7)	5 (2); 6 (1) 33 (1); 34 (2) 7 (1); 9 (1); 10 (1) 7.5 (3)
Scale rows between LL anđ ventral fin Scales arounđ cauđal peđuncle	3.5 12	2.5 (3); 3.5 (19) 12 (17); 13 (4); 14 (1)	3.5 (8) 13 (2); 14 (1); 16 (2); 18 (1); đ (2)	3.5 (3) 14 (2); 16 (1)