Parauchenoglanis ernstswartzi, 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 : 23-24

Parauchenoglanis ernstswartzi sp. nov.

( Fig. 12 ; Table 3 )

Common English name: Ernstswartz’s grunter.

Common French name: Mâchoiron d’Ernst Swartz.

Holotype: SAIAB 118845 , 96.6 mm SL, Angola, Kasai sub-basin, Luxico, Eastern shore of Lake Carumbo (7°47 ʹ 54.6″S, 19°56 ʹ 46.8″E); DNA sample ES11-BT179: SB9095; collectors Ernst Swartz and Fenton P.D. Cotterill, 4 May 2011 .

Paratypes (N = 3): Angola: SAIAB 235742 (ex SAIAB 118845), three, 92.0– 105.6 mm SL, locality details same as holotype, DNA sample ES11-BT178: SB9094 and ES11-BT196: SB9093 .

Diagnosis: Parauchenoglanis ernstswartzi is distinguished from P.ahli , P. altipinnis , P. balayi , P. buettikoferi , P. longiceps , P. monkei , P. pantherinus , P. punctatus , and P. zebratus by eyes situated dorsally, i.e. high on the head towards its upper edge, and round snout profile (vs. eyes situated dorsally and bluntly triangular snout profile). Parauchenoglanis ernstswartzi is distinguished from P. stiassnyae by a truncated caudal fin (vs. rounded), spotted fins (vs. unspotted pectoral, pelvic and anal fin), vertical rows of blotches interspaced by reticulated pattern (vs. irregularly scattered large blotches and absence of reticulated pattern on the flank), in addition to shorter barbels, with external mandibular barbel not reaching the tip of the pectoral-fin spine (vs. barbels long, with external mandibular barbel reaching beyond the tip of the pectoral-fin spine). Parauchenoglanis ernstswartzi is distinguished from species of P. ngamensis species group by a round snout profile (vs. bluntly triangular in P. ngamensis , P. lueleensis , P. patersoni , P. dolichorhinus , P. poikilos , P. chiumbeensis , and P. luendaensis or partly round in P. megalasma ); eyes situated dorsally (vs. eyes situated dorsolaterally in P. ngamensis , P. lueleensis , P. patersoni , P. dolichorhinus , P. poikilos , P. chiumbeensis , P. luendaensis , and P. megalasma ), black spots at the base of the pectoral fin [ Fig. 12C ; vs. absent in P. ngamensis ( Fig. 5C ), P. patersoni ( Fig. 11C ), P. dolichorhinus ( Fig. 8C ), P. lueleensis ( Fig. 10C ), P. poikilos ( Fig. 11C ), P. megalasma ( Fig. 13C ), P. chiumbeensis ( Fig. 14C ), and P. luendaensis ( Fig. 15C )], black blotches (eye size) forming six to seven vertical rows extending onto adipose fin [ Fig. 12A ; vs. five to seven vertical rows of black spots or blotches not extending onto adipose fin in P. ngamensis ( Fig. 5A ), P. patersoni ( Fig. 11A ), P. dolichorhinus ( Fig. 8A ), P. lueleensis ( Fig. 10A ), P. poikilos ( Fig. 11A ), P. megalasma ( Fig. 13A ), P. chiumbeensis ( Fig. 14A ), and P. luendaensis ( Fig. 15A )], and vermiculated pattern on the background [ Fig. 12A ; vs. spots on the background in P.ngamensis ( Fig. 5A ), P. lueleensis ( Fig. 10A ), and P. poikilos ( Fig. 11A ) or no background spots in P. patersoni ( Fig. 11A ), P. dolichorhinus ( Fig. 8A ), P. chiumbeensis ( Fig. 14A ), and P. luendaensis ( Fig. 15A )]. It is further distinguished from P. ngamensis , P. patersoni , P. dolichorhinus , P. lueleensis , P. luendaensis , and P. chiumbeensis by heavily spotted barbels (vs. unspotted). Parauchenoglanis ernstswartzi is further distinguished from P. dolichorhinus by wider interpectoral distance, 19.8%–20.6% SL (vs. narrow, 12.4%–18.2% SL in P. dolichorhinus ). It is further distinguished from P. dolichorhinus , P. lueleensis , and P. poikilos by deeper body depth, 18.2%–19.9% SL (vs. shallow, 11.6%–14.0% SL in P.dolichorhinus , 15.0%–17.4% SL in P. lueleensis , and 16.0%–16.2% SL in P. poikilos ).

Description: Morphometric and meristic data are given in Table 3 . Body elongated. Dorsal body profile flat, slightly rising from snout tip to origin of dorsal fin, straight from dorsal-fin origin to caudal-fin base. Body depth highest at origin of dorsal fin. Ventral body profile 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 at the base of dorsal fin, ending posteriorly to end of anal-fin base. Dorsal and pectoral fins with strong spines. Dorsal-fin short with long base, originating anterior to pelvic-fin origin. Pectoral fin with strong spine. Posterior tip of pectoral-fin rays does not reach pelvic fins. Posterior tip of pelvic-fin rays does not reach anal fin. Entire posterior margin of the pectoral-fin spine serrated, and anterior margin serrated on the distal end. Caudal fin truncated. Fleshy flanges along the dorsal and ventral edges of the base of caudal fin.

Head moderately depressed. Snout profile round, on dorsal view ( Fig. 12B ). Mouth subterminal. Lips fleshy. Eyes big and situated dorsally, orbits projecting on the head. Three pairs of barbels, base thick and tips pointed. External mandibular barbel longest, almost reaching the tip of pectoral-fin spine. Inner mandibular barbel shortest, reaching posterior edge of eye. Maxillary barbel reaching behind posterior edge of the eye but not reaching the base of pectoral-fin spine. Posterior nostril slits positioned about halfway between snout tip and eye.

Colouration in alcohol: Body black dorsally, light brown laterally (below lateral line), and cream ventrally. Body with black blotches (i.e. irregularly shaped spots) about eye size, forming six to seven vertical rows, with rows also extending onto adipose fin. Vermiculated pattern present in between vertical rows. Head black, with black blotches smaller than those on body. Fins with black spots arranged along the rays. Distal tip of fin rays with black markings. Barbels with numerous black spots.

Distribution: Parauchenoglanis ernstswartzi is currently reported from the Lake Carumbo on the Luxico River, the upstream part of the Loange River, a left bank affluent of the Kasai River (see Poll 1967), the latter being a left bank affluent of the middle Congo Basin.

Etymology: The species ephitet ‘ ernstswartzi ’ is dedicated to Dr Ernst Swartz, who collected specimens used in the description of six new species in this study. This dedication is in recognition of his pioneering and extensive exploration of the Kwanza and adjacent river systems, including the upper Kasai sub-basin.

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 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.