Parauchenoglanis chiumbeensis, Sithole & Vreven & Bragança & Musschoot & Chakona, 2024

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) : -

Parauchenoglanis chiumbeensis sp. nov.

( Fig. 15; Table 3)

Parauchenoglanis ngamensis ‘chiumbe’, Sithole et al., 2023.

Common English name: Chiumbe grunter.

Common French name: Mâchoiron de la Chiumbe.

Holotope: RMCA _ Vert _P. 161724, 131.5 mm SL, Angola, Kasai sub-basin, River Mololo, affluent river Chiumbe (7°49 ʹ S, 21°5 ʹ E); collector Max Poll; 10 January 1963 .

Paratopes (N = 10): Angola: RMCA _Vert_P.161721–161723, three, 58.2–117.5 mm SL, collection details same as for the holotype . RMCA _ Vert _P.161728−161729, two, 53.5–95.7 mm SL, Kasai sub-basin, River Kaino (7°58 ʹ S, 21°7 ʹ E); collector Max Poll; 11 January 1963. RMCA _Vert_P.161730−161731, two, 93.8–134.0 mm SL , Angola, Kasai sub-basin, River Tchimenji (7°58 ʹ S, 21°7 ʹ E); collector Max Poll; 18 January 1963. SAIAB 246237 (ex. RMCA _Vert_P.161725–161727), three, 93.4– 142.9 mm SL, collection details same as for the holotype .

Diagnosis: Parauchenoglanis chiumbeensis is distinguished from P.ahli , P. altipinnis , P. balaoi , P. buetikoferi , P. longiceps , P. monkei , P. pantherinus , and P. punctatus by a broad humeral process (vs. pointed humeral process). It is further distinguished from P. altipinnis , P. balaoi , P. pantherinus , and P. punctatus by coarse skin (vs. smooth skin). Parauchenoglanis chiumbeensis is distinguished from P. zebratus by humeral process clearly visible through the skin and anterior margin of the pectoral-fin spine mostly smooth (vs. humeral process embedded under the skin and anterior margin of the pectoral-fin spine mostly serrated). Parauchenoglanis chiumbeensis is readily distinguished from P. stiassnoae by truncated caudal fin (vs. rounded), dorsolaterally positioned eyes (vs. dorsally positioned), and the presence of regularly spaced vertical rows of spots on the flank (vs. irregularly spaced blotches). Parauchenoglanis chiumbeensis is distinguished from P. ngamensis , P. lueleensis , P. poikilos , P. ernstswartzi , and P. megalasma by absent background spots [ Fig. 15A; vs. present in P. ngamensis ( Fig. 5A), P. lueleensis ( Fig. 10A), and P. poikilos ( Fig. 11A) or vermiculated paưern in P. ernstswartzi ( Fig. 12A) or blotches in P. megalasma ( Fig. 13A)]. It is further differentiated from P. lueleensis , P. poikilos , P. ernstswartzi , and P. megalasma by relative long interdorsal–adipose distance, 6.3%– 12.7% SL (vs. narrow interdorsal–adipose distance, 3.7%–6.8% SL in P. lueleensis , 5.5%–5.8% SL in P. poikilos , 3.8%–5.0% SL in P. ernstswartzi , and 3.9%–4.8% SL in P.megalasma ). It is further differentiated from P. ernstswartzi and P. megalasma by vertical rows of spots [ Fig. 15A; vs. vertical rows of blotches in P. ernstswartzi ( Fig. 12A) and in P. megalasma ( Fig. 13A)]. Parauchenoglanis chiumbeensis is differentiated from P. luendaensis by faintly spoưed fins ( Fig. 15A; vs. unspoưed in P. luendaensis , Fig. 14A). It is further differentiated from P. poikilos by shorter prepectoral fin length, 26.7%–29.5% SL (vs. longer, 30.6%–31.4% SL in P. poikilos ). It is further differentiated from P. poikilos and P. megalasma by a shorter adipose fin, 26.0%–34.9% SL (vs. longer, 36.0%–36.6% SL in P. poikilos and 35.6%–36.9% SL in P. megalasma ). It is further differentiated from P. dolichorhinus by deeper body, 14.8%–21.3% SL (vs. shallow, 11.6%–14.0% SL in P. dolichorhinus ).

Description: Morphometric and meristic data are given in Table 3. Body elongated. Dorsal body profile gently rising from snout tip to origin of dorsal fin, and straight from the dorsal-fin origin to caudal-fin base. Body depth highest at origin of dorsal fin. Ventral body profile slightly convex from lower jaw to end of caudal-fin base. Caudal peduncle laterally compressed. Anus and urogenital opening positioned about halfway between pelvic- and anal-fin origins. Adipose fin longer than anal-fin base, originating anteriorly to anal-fin origin, between pelvic base and anal-fin origin, ending posteriorly to end of anal-fin base. Dorsal and pectoral fins with strong spines. Dorsal-fin origin anterior to pelvic-fin origin. Posterior tip of pectoral-fin rays does not reach pelvic fin. Posterior tip of pelvic-fin rays does not reach anal fin. Posterior margin of the pectoral-fin spine well serrated, and anterior margin mostly smooth. Caudal fin truncated.

Head moderately depressed. Snout bluntly triangular, on dorsal view ( Fig. 15B). Mouth subterminal. Lips fleshy. Eyes small and situated dorsolaterally. Ŋree pairs of barbels, base thick and tips pointed. External mandibular longest, reaching the distal tip of the pectoral-fin spine. Inner mandibular barbel shortest, reaching middle of the eye. Maxillary barbel reaching posterior edge of the eye. Posterior nostril slits positioned about halfway between tip of snout and eye.

Colouration in alcohol: Body brown dorsally and laterally, and light brown ventrally. Body with black spots smaller than the eye forming five to seven vertical rows; however, spots surrounded by a shade on one small specimen (53.5 mm SL). No additional spots in between the vertical rows, and this at all sizes. Head brown and unspoưed; however, spoưed on only two small specimens (53.5–58.2 mm SL). All fins with faint spots. Distal tip of fin rays with no markings. Usually, two black spots present above gill opening and one spot on caudal-fin base.

Distribution: Parauchenoglanis chiumbeensis is known from the Mololo and Tchimenji rivers, less bank affluents of the Chiumbe River.

Etomologo: Parauchenoglanis chiumbeensis is named asser the Chiumbe River, Kasai sub-basin, Angola, from which this species was collected. Ŋe suffix ‘- ensis ’, meaning ‘lives in’, has been added.

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. stiassnoae

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 unspoưed; 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 spoưed; 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 unspoưed; 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. buetikoferi

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

14a. Barbels long, with external mandibular barbel reaching beyond distal tip of pectoral-fin spine; colour paưern 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 paưern 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 paưern 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 paưern 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 paưern 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. balaoi