Synodontis species, 1816

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), pp. 1-38 : 35

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 )

Figures

Figure 5.General appearance of Synodontis dhonti (MRAC 14344, holotype, 320.4 mm SL, Baie de Kilewa) and shape of humeral process (inset:white outline).

Figure 6. General appearance of Synodontis granulosus and shape of humeral process (inset: white outline). A, NMW 100723 (specimen 22-ZM-308), 90.2 mm SL, Mpulungu fish market.B, BMNH 1906.9.6.40, lectotype, S. granulosus, 213.1 mm SL, north end of Lake Tanganyika.

Figure 7. General appearance of Synodontis irsacae and shape of humeral process (inset: white outline). A, NMW 100774 (specimen 23-TZ- 312), 104.6 mm SL, Cape Kabogo. B, NMW 100780 (specimen 23-IMP-014), 101.2 mm SL, Kibige. C, NMW 100767 (specimen 22-ZM- 385), 97.2 mm SL, Katukula.

Figure 8. General appearance of Synodontis multipunctatus and shape of humeral process (inset: white outline). A, NMW 100756 (specimen 23-TZ-331), 116.3 mm SL, Cape Kabogo. B, BMNH 1898.9.9.76, holotype, S.multipunctatus, 222.5 mm SL, Sumbu. C, BMNH 1936.6.15.1206-1226, 214.9 mm SL, Kibanga Bay.

Figure 9. General appearance of Synodontis multipunctatus, resembling specimens identified as Synodontis grandiops, and shape of humeral process (inset: white outline). A, NMW 100761 (specimen 23-IMP-007), 77.8 mm SL, Rutunga. B, BMNH 1982.4.13.4785, holotype, S. grandiops, 94.7 mm SL, Mwakizega coastline. C, BMNH 1936.6.15.1206–1226, 103.6 mm SL, Kibanga Bay.

Figure 10. General appearance of Synodontis petricola and shape of humeral process (inset: white outline). A, ‘petricola phenotype’, NMW 100713 (specimen 23-TZ-56), 111.0 mm SL, Nondwa Point, Kigoma.B, ‘lucipinnis phenotype’, NMW 100715 (specimen 23-TZ-41), 114.2 mm SL, Hilltop, Kigoma. C, ‘dark phenotype’, NMW 100710 (specimen 22-ZM-531), 78.5 mm SL, Kalambo.

Figure 11. General appearance of Synodontis polli and shape of humeral process (inset: white outline).A, NMW 100739 (specimen 23-TZ- 127), 152.1 mm SL, Mabilibili.B, NMW 100741 (specimen 23-IMP-025), 150.0 mm SL, Kibige.C, NMW 100736 (specimen 23-TZ-305), 104.0 mm SL, Cape Kabogo.

Figure 12. General appearance of Synodontis tanganyicae and shape of humeral process (inset: white outline). A, lectotype of S. tanganyicae, drawing in the paper by De Vos and Thys van den Audenaerde (1998: fig.1). B, holotype of S. lacustricolus, drawing in the paper by Poll (1953: fig. 18a). C, BMNH 1936.6.15.1203–1205, 423.0 mm SL, Lake Tanganyika.

Figure 13. General appearance of Synodontis afrofischeri from the Malagarasi River drainage and shape of humeral process (inset: white outline).A, BMNH 1971.6.22.111–113, 123.8 mm SL, Kasanda Bay, Malagarasi River, Lake Tanganyika basin. B, BMNH 1971.6.22.111–113, 127.7 mm SL, Kasanda Bay, Malagarasi River, Lake Tanganyika basin.C, BMNH 1971.6.22.116, 145.0 mm SL, Katare, Lake Tanganyika basin.

Figure 14. General appearance of Synodontis melanostictus and shape of humeral process (inset: white outline). A, NMW 100724 (specimen 21-ZM-252), 121.0 mm SL, Ndole Bay, Lake Tanganyika. B, BMNH 1906.9.8.72, 237.0 mm SL, holotype, S. melanostictus, Lofu, Lake Tanganyika basin.

Figure 15. General appearance of Synodontis victoriae and shape of humeral process (inset: white outline).A, BMNH 1971.6.22.118, 142.4 mm SL, Kasanda Bay, Malagarasi River, Lake Tanganyika basin.B, BMNH 1971.6.22.117, 152.7 mm SL, Kasanda Bay, Malagarasi River, Lake Tanganyika basin. C, BMNH 1906.5.30.190, 225.0 mm SL, paralectotype S. victoriae, Buganga, Lake Victoria.