Synodontis victoriae Boulenger, 1906

Englmaier, Gernot K., Blažek, Radim, Zimmermann, Holger, Bartáková, Veronika, Polačik, Matej, Žák, Jakub, Mulokozi, Deogratias P., Katongo, Cyprian, Büscher, Heinz H., Mabo, Lwabanya, Koblmüller, Stephan, Palandačić, Anja & Reichard, Martin, 2024, Revised taxonomy of Synodontis catfishes (Siluriformes: Mochokidae) from the Lake Tanganyika basin reveals lower species diversity than expected, Zoological Journal of the Linnean Society 202 (3) : -

Synodontis victoriae Boulenger, 1906

( Fig. 15)

Synodontis victoriae Boulenger, 1906: 438 ( Boulenger 1906b) (type locality: Entebbe , Lake Victoria [Victoria Nyanza], Uganda).

Material examined: Type material: BMNH 1906.5 .30.191, lectotype, S. victoriae , 188.2 mm SL, Entebbe , Lake Victoria, coll. Degen , 1906. BMNH 1906.5 .30.190, paralectotype, S. victoriae , 225.0 mm SL, Buganga , Lake Victoria, Uganda, coll. Degen , 1906.

Non-type material: BMNH 1912.10.15.48–50, two, 104.4– 130.1 mm SL, Malawa River , Uganda, don. Jackson . BMNH 1982.4.19.956–958, two, 122.0– 153.2 mm SL, Lake Victoria near Rusinga Island , Kenya, don. Kisumu Laboratory . BMNH 1971.6 .22.118, one, 142.4 mm SL, Kasanda Bay, Malagarasi River, Lake Tanganyika basin, Tanzania, coll. Greenwood , Lowe-McConnell, Lockley , 1952 . BMNH 1971.6 .22.117, one, 152.7 mm SL, Kasanda Bay, Malagarasi River, Lake Tanganyika basin, Tanzania, coll. Greenwood , Lowe-McConnell, Lockley . MRAC 2011.003 .P.1201–1204, three, 112.0– 126.5 mm SL, Rivière Muyovozi, ± 900 m du pont à gauche, route Rutana- Giharo , bassin Malagarazi, Burundi, coll. Banyankimbona , 2010. MRAC 2010.003 .P.0521–0522, two, 84.2–92.6 mm SL, Riv. Malagarazi, Mutwana, parcelle Nyabantu , ± 1000 m vers l’amont, ku kigazo kwa Nyamwikinga, Burundi, coll. Banyankimbona , 2009. MRAC 2010.003 .P.0520, one, 98.7 mm SL, Ku kigazo kwa Misago; Riv. Malagarazi , Mutwana , passerelle de Gasenyi, ± 500 m vers l’amont, Burundi, coll. Banyankimbona , 2009. MRAC 2010.003 .P.0534, one, 107.4 mm SL, Riv. Mukazye, 600 m du pont route Giharo-Kinyinya, bassin Malagarazi , Burundi, coll. Banyankimbona , 2009. MRAC 2012.007 .P.0102, one, 76.9 mm SL, Rivière Rumpungwe, colline Ngomante, sous-colline Sesa , près de passerelle Gombo , bassin Malagarazi , Burundi, coll. Banyankimbona , 2011. MRAC 2012.007 .P.0100, one, 82.3 mm SL, Rivière Rumpungwe, colline Ngomante, sous-colline Sesa , près de passerelle Gombo , bassin Malagarazi , Burundi, coll. Banyankimbona , 2011. MRAC 2012.007 .P.0101, one, 72.5 mm SL, Rivière Rumpungwe, colline Ngomante, sous-colline Sesa , près de passerelle Gombo , bassin Malagarazi , Burundi, coll. Banyankimbona , 2011. MRAC 2010.003 .P.0567, one, 126.9 mm SL, Riv. Rumpungwe, colline Ngomante, sous-colline Sesa , bassin Malagarazi , Burundi, coll. Banyankimbona , 2009. MRAC 2010.003 .P.0561, one, 128.3 mm SL, Ku kigazo kwa Misago; Riv. Malagarazi , Mutwana , passerelle de Gasenyi, ± 500 m vers l’amont, Burundi, coll. Banyankimbona , 2009. MRAC 2010.003 .P.0563-0564, one, 116.3 mm SL, Riv. Malagarazi, colline Bigina, commune Kayogoro , Burundi, coll. Banyankimbona , 2009. MRAC 2011.003 .P.1220–1233, one, 65.4 mm SL, Riv. Malagarazi, au village des marais Ku Mutongotongo , séparation plantation cannes à sucre et rivière, Burundi, coll. Banyankimbona , 2010.

Diagnosis: Synodontis victoriae is distinguished from congeners in the LT basin by a unique combination of characters: axillary pore absent; no granular papillae on head, body, and fins; dorsal spine sparsely pigmented; anal fin commonly without spots; 18–29 (median 22) mandibular teeth, arranged in four symmetric rows of replacement teeth; 16–29 (median 23) primary premaxillary teeth; 0–3 (median 1) secondary branches on inner mandibular barbels; and 39–42 (median 40) total vertebrae, with 20–23 (median 21) caudal vertebrae.

Description: The general appearance of S. victoriae is shown in Figure 15; axial skeletons in Supporting Information, Figure S8Q, R; and relative measurements, meristic counts, and coded characters are given in Supporting Information, Table S12.

Longest examined specimen 225.0 mm SL (undetermined sex, BMNH 1906.5.30.190, paralectotype). Body moderately compressed laterally. Dorsal head profile and predorsal back rising straight or slightly convex to dorsal-fin origin at an angle of 16°–27° (against midline of body), large specimens slightly concave at nape. Postdorsal profile falling straight to adipose-fin origin and usually convex to caudal-fin origin. Body depth at anal-fin insertion greater than half of body depth at dorsal-fin origin. Head dorsoventrally compressed; depth at posterior eye margin equal to or greater than maximal cranium width. Snout blunt and usually shorter than half of head length. Mouth subterminal, with abundant papillae on lips; width 61.8%–84.5% of snout length. Eye diameter less than half the snout length.

Head, body, and fins without papillae. Occipitonuchal shield and humeral process rugose. Humeral process broad and triangular, upper margin slightly concave; maximal depth 39.5%– 49.3% (N = 8) of its length. Axillary pore absent.

Adipose fin well demarcated; basal length 20.8%–32.9% of SL, extending over 42.2%–64.9% of distance between dorsal-fin insertion and end of caudal peduncle. Adipose-fin insertion distant to end of caudal peduncle. Dorsal fin with two unbranched rays and seven branched rays; dorsal spine with well-marked serrations on lower anterior edge, poorly serrated on upper anterior edge, posterior edge with 4–19 serrae; length of dorsal spine, excluding upper flexible part, 73.1%–103.0% of head length. Anal fin commonly with five unbranched rays and eight or nine branched rays; longest branched rays reaching beyond level of posterior edge of adipose fin. Pelvic fin with a single unbranched ray and six branched rays. Pectoral fin with a single unbranched ray and commonly eight branched rays; pectoral spine strongly serrated on anterior (23–41 serrae) and posterior (10–20 serrae) edges. Pectoral fin usually shorter than pectoral–pelvic distance. Caudal fin forked, with 2 + 15 principal rays; number of upper procurrent rays (11–13, median 12, N = 6) less than lower procurrent rays (13–16, median 14, N = 7).

Mandibular teeth 18–29 (median 22, N = 20) (lectotype 18), unicuspid, commonly arranged in four symmetric rows of replacement teeth. Primary premaxillary teeth 16–29 (median 23, N = 20) (lectotype 27), arranged in two irregular rows.

Maxillary barbels long, usually reaching beyond pectoral-fin insertion (only in 3 of 20 specimens shorter). Outer mandibular barbels 49.8%–84.3% of head length, with 4–6 (median 5, N = 20) primary branches; secondary branches absent. Inner mandibular barbels with 5–9 (median 8, N = 20) primary branches and 0–3 (median 1, N = 20) secondary branches.

Total vertebrae 39–42 (median 40, N = 16) (lectotype 39), abdominal vertebrae 17–20 (median 19), preanal caudal vertebrae 2–4 (median 2), and postanal caudal vertebrae 18–20 (median 19).

Coloration: In formalin (initial fixation) and later transferred to 75% ethanol ( Fig. 15A, B), body coloration variable, ranging from light brown to dark grey; ventral side cream in colour. Commonly with abundant black spots on head, body, and adipose, caudal, and dorsal fins; spots absent on ventral side. Some specimens examined from the Malagarasi River without spots on dorsal and lateral side of body ( Fig. 15A), but spots present on caudal and dorsal fins. Maxillary and mandibular barbels cream coloured or brownish.

After long-term preservation in 75% ethanol ( Fig. 15C), historical specimens brown, darker on dorsal side. Some specimens with brown spots on dorsal and lateral sides and adipose fin.

Distribution and habitat: Widely distributed in the upper Nile River drainage, including the basins of lakes Victoria and Kyoga (Poll 1971, Seegers et al. 2003). Reported from rocky and sandy bottom substrates. In the LT basin, S. victoriae is known only from the Malagarasi River drainage (Poll 1971, De Vos et al. 2001) ( Fig. 1).

Key to Synodontis species of the Lake Tanganyika basin

1a. Large, conspicuous axillary pore present at anterior ventral margin of humeral process ( Figs 5, 6, 8, 9, 12C) 2

1b. Axillary pore absent or axillary pore small or only skin fold visible ( Figs 7, 10, 11, 13–15) ............................................................5

2a. Mandibular teeth 38–50, arranged in eight or 10 symmetric rows of replacement teeth ..................................................................3

2b. Mandibular teeth 13–29, arranged in four or six symmetric rows of replacement teeth ...................................................................4

3a. Total vertebrae 41–45 (median 43); secondary branches on inner mandibular barbels 0–5 (median 0); snout length 46.0%– 56.5% (mean 48.7%) of head length; length of inner mandibular barbels 34.7%–70.7% (mean 47.8%) of outer mandibular-barbel length ................................................................................................................................................................. S. granulosus ( Fig. 6)

3b. Total vertebrae 40–41 (median 41); secondary branches on inner mandibular barbels 4–8 (median 6); snout length 50.3%– 60.0% (mean 55.4%) of head length; length of inner mandibular barbels 28.3%–41.7% (mean 36.4%) of outer mandibular-barbel length ............................................................................................................................................................ S. tanganyicae ( Fig. 12)

4a. Head and body with abundant granular papillae; spots absent................................................................................... S. dhonti ( Fig. 5)

4b. Head and body with few papillae, usually restricted to head, non-granular; abundant black spots on head and body................. ............................................................................................................................................................................ S. multipunctatus ( Figs 8, 9)

5a. Caudal-fin lobes with black bars, never without pigmentation or only spots; head and body usually with abundant black spots ( Figs 7, 10, 11) ................................................................................................................................................................................................6

5b. Caudal-fin lobes never with black bars, caudal fin usually with abundant black or dark brown spots; head and body with or without dark spots ( Figs 13–15) .................................................................................................................................................................8

6a. Mandibular teeth 41–68 (median 53), commonly arranged in eight symmetric rows of replacement teeth; head and body with abundant villous papillae.......................................................................................................................................... S. polli ( Fig. 11)

6b. Mandibular teeth 18–48, commonly arranged in four or six symmetric rows of replacement teeth; head and body with few papillae, usually restricted to head ..............................................................................................................................................................7

7a. Dorsal spine usually completely white; 87%–100% (mean 97%) of first branched dorsal-fin ray dark (from base) vs. 0%–13% (mean 3%) white (from tip); mandibular teeth 31–48 (median 39)................................................................. S. petricola ( Fig. 10)

7b. Dorsal spine never completely white, only white at tip and upper flexible part; 56%–76% (mean 66%) of first branched dorsal-fin ray dark (from base) vs. 24%–44% (mean 34%) white (from tip); mandibular teeth 18–35 (median 24)................. ................................................................................................................................................................................................ S. irsacae ( Fig. 7)

8a. Primary premaxillary teeth 33–57 (median 43); mandibular teeth 42–64 (median 49), arranged in six symmetric rows of replacement teeth; head and body with marbled body coloration .................................................................... S. afrofischeri ( Fig. 13)

8b. Primary premaxillary teeth 16–64; mandibular teeth 18–38, arranged in four or six symmetric rows of replacement teeth; head and body with or without dark spots, never with marbled coloration pattern.........................................................................9

9a. Primary premaxillary teeth 34–64 (median 46); head, body, and fins with abundant dark spots........ S. melanostictus ( Fig. 14)

9b. Primary premaxillary teeth 16–29 (median 23); head, body, and fins with or without dark spots............... S. victoriae ( Fig. 15)