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), pp. 1-33 : 27-28

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.

Holotype: 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 .

Paratypes (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. balayi , P. buettikoferi , 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. balayi , 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. stiassnyae 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 pattern 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 spotted fins ( Fig. 15A ; vs. unspotted 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. Three 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 unspotted; however, spotted 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, left bank affluents of the Chiumbe River.

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

Figures

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 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.