Parauchenoglanis, Boulenger, 1911

Sithole, Yonela, Vreven, Emmanuel J. W. M. N., Bragança, Pedro H. N., Musschoot, Tobias & Chakona, Albert, 2024, Nine in one: integrative taxonomic evidence of hidden species diversity in the widespread Zambezi grunter, Parauchenoglanis ngamensis (Siluriformes: Auchenoglanididae), from southern and south-central Africa, Zoological Journal of the Linnean Society 202 (3), pp. 1-33 : 28-29

Identification key to Parauchenoglanis species

1a. Humeral process broadly triangular............................................................................................................................................................2

1b. Humeral process pointed........................................................................................................................................................................... 11

2a. Humeral process embedded under the skin; anterior margin of the pectoral-fin spine mostly serrated..................... P. zebratus

2b. Humeral process clearly visible through the skin; anterior margin of the pectoral-fin spine mostly smooth .............................3

3a. Rounded caudal fin ( Fig. 4A ).......................................................................................................................................................................4

3b. Truncated caudal fin ( Fig. 4B ) .....................................................................................................................................................................7

4a. Long barbels, external mandibular barbel reaching beyond distal tip of pectoral spine; total vertebrae count <30 ................... ......................................................................................................................................................................................................... P. stiassnyae

4b. Short barbels, external mandibular barbel never reaching beyond the distal tip of pectoral; total vertebrae count ≥32 ........... ............................................................................................................................................................................................................................5

5a. Head and fins with numerous black spots at all sizes (22.8–204.2 mm SL); body of medium- to large-sized specimens (>50.0 mm SL) with numerous spots, with some of them forming five to seven (median six) vertical rows and with other black spots situated in between those rows ( Fig. 5 )............................................................................................................ P. ngamensis

5b. Head and fins with few black spots or spots entirely absent at all sizes (32.1–223.0 mm SL); body of medium- to large-sized specimens (> 100 mm SL) with black spots forming only five to six (median six, rarely seven) vertical rows and with no other spots situated in between these rows..........................................................................................................................................................6

6a. Head moderately depressed (head depth 48.5%–54.0% HL); deeper body depth, 15.5%–21.4% SL ( Fig. 11 ) ......................... ........................................................................................................................................................................................................ P. patersoni

6b. Head highly depressed (head depth 34.6%–40.0% HL); shallower body depth, 11.6%–14.0% SL ( Fig. 8 ) ................................ ................................................................................................................................................................................................ P. dolichorhinus

7a. Snout round or partly round; body with vertical rows of black blotches; head with black blotches.............................................8

7b. Snout bluntly triangular; body with black spots; head sometimes also with black spots................................................................9

8a. Vertical rows of black blotches extending onto adipose fin; blotches along the lateral line smaller than the eye size; eyes situated dorsally, i.e. high on the head, towards its upper surface ( Fig. 12 ) ..................................................................... P. ernstswartzi

8b. Vertical rows of black blotches not extending onto adipose fin; blotches along the lateral line larger than the eye size; eyes clearly situated dorsolaterally ( Fig. 13 ).............................................................................................................................. P. megalasma

9a. Head and fins with black spots; black spots present in between vertical rows of spots; external mandibular barbel not reaching the distal tip of pectoral-fin spine, when adpressed along the body ................................................................................. 10

9b. Head and fins without black spots or with faint black spots only; absence of black spots in between vertical rows of spots; external mandibular barbel reaching the distal tip of pectoral-fin spine, when adpressed along the body ............................... 11

10a. Mandibular barbels unspotted; only one or two black spots in between vertical rows of black spots; long predorsal length, 39.4%–42.0% SL ( Fig. 10 )........................................................................................................................................................ P. lueleensis

10b. Mandibular barbels spotted; more than two black spots in between vertical rows of black spots; short predorsal length, 38.4%–39.2% SL ( Fig. 11 )........................................................................................................................................................... P. poikilos

11a. Fins unspotted; high adipose fin height ( Fig. 14 )............................................................................................................ P. luendaensis

11b. Fins with faint black spots; low adipose fin height ( Fig. 15 ) ...................................................................................... P. chiumbeensis

12a. Anterior margin of the pectoral-fin spine completely serrated........................................................................................................... 13

12b. Anterior margin of the pectoral-fin spine only partly and slightly serrated, or smoothly serrated ............................................. 15

13a. Caudal peduncle relatively long as high ............................................................................................................................... P. buettikoferi

13b. Caudal peduncle shorter than high.......................................................................................................................................................... 14

14a. Barbels long, with external mandibular barbel reaching beyond distal tip of pectoral-fin spine; colour pattern with 6–10 (rarely 11) vertical rows of spots .............................................................................................................................................. P. punctatus

14b. Barbels short, with external mandibular barbel not reaching beyond distal tip of pectoral spine; colour pattern with five to seven bands....................................................................................................................................................................................... P. monkei

15a. Preorbital head length greater than maximum head depth (measured at level of supraoccipital process); numerous small black spots on both head and fins............................................................................................................................................................. 16

15b. Preorbital head length less than maximum head depth; colour pattern of body and fins variable, but not as above.............. 17

16a. Interorbital distance 28%–30% HL; spots on head and flanks of equal size ..................................................................... P. longiceps

16b. Interorbital distance 22%–25% HL; spots on head smaller than those on flanks...................................................... P. pantherinus

17a. Adipose and dorsal fins high (adipose fin height, 5%–8% SL; dorsal fin height, 19%–30% SL); colour pattern on flank faint, one horizontal row of two to six large spots, being as large as or larger than the eye diameter, visible on the level of lateral line .......................................................................................................................................................................................................... P. altipinnis

17b. Adipose and dorsal fins shallower (adipose fin height, 3%–7% SL; dorsal fin height, 15%–25% SL); colour pattern of body and fins variable but not as above............................................................................................................................................................. 18

19a. Barbels long, with external mandibular barbel reaching distal tip of pectoral spine (minimum one-third HL); whole body covered with spots of equal size.......................................................................................................................................................... P.ahli

19b. Barbels short, with external mandibular barbel never reaching beyond distal tip of pectoral spine (shorter than one-third HL); whole body covered with spots of different sizes, arranged in horizontal and/or vertical rows............................. P. balayi

Figures

Figure 4. Lateral view of the shape of the caudal fin for the species within the Parauchenoglanis ngamensis group. A, typical round caudal fin for southern African species [P.ngamensis sp. ‘kwanza 1’ (= P.patersoni): SAIAB 84804, 192.9 mm SL].B, truncated caudal fin typical for southcentral African species, i.e. Kasai sub-basin species [P. ngamensis sp. ‘luenda’ (= P. luendaensis): RMCA_Vert_P.161764, 102.2 mm SL].

Figure 5. Photographs of the holotype of Parauchenoglanis ngamensis, BMNH 1910.5.31.35, 184.5 mm SL, Okavango River.A, lateral view.B, dorsal view. C, ventral view. Scale bar: 1 cm.

Figure 8. Photograph of the holotype of Parauchenoglanis dolichorhinus, SAIAB 84886, 139.8 mm SL, Kwanza River. A, lateral view.B, dorsal view. C, ventral view. Scale bar: 1 cm.

Figure 10. Photograph of the holotype of Parauchenoglanis lueleensis, SAIAB 118796, 95.4 mm SL, Luele River (Kasai). A, lateral view.B, dorsal view.C, ventral view. Scale bar: 1 cm.

Figure 11. Photograph of the holotype of Parauchenoglanis poikilos, SAIAB 99100, 57.2 mm SL, Lovua River (Kasai). A, lateral view. B, dorsal view.C, ventral view.Scale bar: 1 cm.

Figure 12. Photograph of the holotype of Parauchenoglanis ernstswartzi, SAIAB 118845, 96.6 mm SL, Lake Carumbo (Kasai). A, lateral view.B, dorsal view. C, ventral view. Scale bar: 1 cm.

Figure 13. Photograph of the holotype of Parauchenoglanis megalasma, SAIAB 118792, 72.5 mm SL, Luele River (Kasai). A, lateral view.B, dorsal view. C, ventral view. Scale bar: 1 cm.

Figure 14. Photograph of the holotype of Parauchenoglanis luendaensis, RMCA_Vert_P.161764, 102.2 mm SL, Luenda River (Kasai). A, lateral view.B, dorsal view. C, ventral view. Scale bar: 1 cm.

Figure 15. Photograph of the holotype of Parauchenoglanis chiumbeensis, RMCA_Vert_P161724, 131.5 mm SL, Chiumbe River (Kasai). A, lateral view.B, dorsal view.C, ventral view. Scale bar: 1 cm.