Parauchenoglanis dolichorhinus, 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 : 20-21

Parauchenoglanis dolichorhinus sp. nov.

( Fig. 8 )

Common English name: Long-snouted grunter.

Common French name: Mâchoiron à long museau.

Holotype: SAIAB 84886, 139.8 mm SL, Angola, Kwanza Basin , Posto 5 (09°48 ʹ 23″S, 15°24 ʹ 30″E); DNA sample ES07F442: SB9092; collector Ernst Swartz, 31 October 2007 .

Paratypes (N = 3): Angola: RMCA_Vert_P.0002 (ex SAIAB 235745), one, 115.1 mm SL, Kwanza Basin, Posto 5 (09°48 ʹ 23″S, 15°24 ʹ 30″E); DNA sample ES07F296: SB9090; collector Ernst Swartz, 24 October 2007. SAIAB 235745 , one, 91.9 mm SL, Kwanza Basin, Posto 5 (09°48 ʹ 23″S, 15°24 ʹ 30″E); collector Ernst Swartz, 24 October 2007. SAIAB 85066 , one, 52.4 mm SL, Kwanza Basin, New dam site (09°41 ʹ 35″S, 14°59 ʹ 55″E); DNA sample ES08B148: SAFW418-08; collector Ernst Swartz, 16 August 2008.

Diagnosis: Parauchenoglanis dolichorhinus 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). It is differentiated from P. buettikoferi and P. monkei by anterior margin of the pectoral-fin spine mostly smooth (vs. anterior margin of pectoral-fin spine serrated from base to tip). Parauchenoglanis dolichorhinus is distinguished from P. zebratus by humeral process clearly visible through the skin, presence of five to six bars on small or vertical rows of spots on large, and anterior margin of the pectoral-fin spine mostly smooth (vs. humeral process embedded under the skin, four to five vertical rows of spots on small specimens or four to five bars on larger specimens, and anterior margin of the pectoral-fin spine mostly serrated). Parauchenoglanis dolichorhinus is distinguished from P. stiassnyae by the absence of black background spots in between the vertical bars or rows of spots (vs. reticulated pattern), a depressed head, head depth 34.6%–40.0% HL (vs. moderately depressed head, head depth 43.5%–58.7% HL), and a narrow body depth, 11.6%–14.0% SL (vs. a deeper body depth, 15.7%–22.7% SL). Parauchenoglanis dolichorhinus is distinguished from all other species of the P. ngamensis species group by a depressed head; head depth 34.6%–40.0% HL (vs. a moderately depressed head; head depth 40.6%–60.8% HL in P. ngamensis , 48.5%–54.9% HL in P. patersoni , 41.2%–50.3% HL in P. lueleensis , 41.7%–42.0% HL in P. poikilos , 49.5%–54.0% HL in P. ernstswartzi , 42.0%–53.5% HL in P. chiumbeensis , and 48.2%– 59.2% HL in P.luendaensis ). It is further distinguished from these species by narrow body depth, 11.6%–14.0% SL (vs. deeper body depth, 14.6%–23.5% SL in P. ngamensis , 15.5%–21.4% SL in P. patersoni , 15.0%–17.4% SL in P. lueleensis , 16.0%–16.2% SL in P. poikilos , 18.2%–19.9% SL in P. ernstswartzi , 20.2%–20.9% SL in P. megalasma , 14.8%–21.3% SL in P. luendaensis , and 14.5%–18.9% SL in P. chiumbeensis ). It is further distinguished from P. lueleensis , P. poikilos , P. ernstswartzi , and P. megalasma by a narrow interpectoral distance, 17.4%–18.2% SL (vs. wider, 18.8%–22.5% SL in P. lueleensis , 18.4%–21.0% SL in P. poikilos , 19.8%–20.6% SL in P. ernstswartzi , and 18.8%–21.9 % SL in P. megalasma ). Finally, it is further distinguished by unspotted fins [ Fig. 8A ; vs. fins with numerous black spots in P. ngamensis ( Fig. 5A ), P. lueleensis ( Fig. 10A ), and P. poikilos ( Fig. 11A ) or faint spots in P. chiumbeensis ( Fig. 15A ) or blotches in P. ernstswartzi ( Fig. 12A ) and P. megalasma ( Fig. 13A )].

Description: Morphometric and meristic data are given in Table 3. A medium-sized species with a maximum observed size of 139.8 mm SL. Body elongated and dorsally depressed from snout tip to origin of dorsal fin. Dorsal body profile convex from tip of snout to dorsal fin origin, straight from dorsal-fin origin to caudal-fin base. Body depth highest at origin of dorsal fin. Ventral body profile slightly concave from lower jaw to 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 spine. Dorsal-fin origin anterior to pelvic-fin origin. Posterior edge of pectoral fin rays does not reach pelvic fins. Entire posterior margin of the pectoral-fin spine serrated, and anterior margin serrated only towards distal end. Caudal fin rounded.

Head depressed. Snout profile bluntly triangular, on dorsal view ( Fig. 8B ). Mouth subterminal. Lips fleshy. Eyes small and situated dorsolaterally. 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 middle of eye. Maxillary barbel reaching beyond 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 life: Body yellow-brown to light brown dorsally and laterally. Distal tips of fins with brown markings (Supporting Information, Fig. S3 ). Arrangement of spots is discussed below.

Colouration in alcohol: Body light brown dorsally and laterally, and cream ventrally. Body with five to six bars in medium-sized specimens (52.4–91.9 mm SL; Fig. 9 ). Large-sized specimens (115.1–139.8 mm SL) with black spots smaller than the eye forming six vertical rows. No additional black spots in between the bars or vertical rows of spots. Head light brown, sometimes with very few, usually <10 black spots, smaller than those on body. Fins with a few black spots, sometimes even unspotted. Distal tip of fin rays with black markings. Usually, two small black spots present above gill opening and one spot on midline of caudal-fin base. Barbels unspotted.

Distribution: Parauchenoglanis dolichorhinus has currently been recorded only from the mainstream section of the Kwanza Basin above and below the Quissaquina Falls ( Fig. 1 ). This species co-occurs with the other Kwanza endemic Parauchenoglanis species, P. patersoni .

Etymology: The species name ‘ dolichorhinus ’ is derived from the Greek ‘ dolichos ’ meaning long and ‘ rhinus ’ meaning snout, referring to the long snout (preorbital length) of this species in comparison to the other species in the P. ngamensis group.

Figures

Figure 1. Map showing sampling localities of P.ngamensis used in this study. A = Zambezi and Okavango basins, B = Kwanza Basin and Kasai Sub-basin.Symbols and abbreviations:Parauchenoglanis ngamensis sp. ‘okavango-zambezi’ (= P.ngamensis): *, holotype, ●, Okavango, and ●, Zambezi specimens; P. ngamensis sp. ‘kwanza 1’ (= P. patersoni): ●; P. ngamensis sp. ‘kwanza 2’ (= P. dolichorhinus):; P. ngamensis sp. ‘kasai 1’ (= P. lueleensis): ●; P. ngamensis sp. ‘kasai 2’ (= P. poikilos): ●; P. ngamensis sp. ‘kasai 3’ (= P. ernstswartzi): ●; P. ngamensis sp. ‘kasai 4’ (= P. megalasma):; P. ngamensis sp. ‘luenda’ (= P. luendaensis): ● and P. ngamensis sp. ‘chiumbe’ (= P. chiumbeensis): ●. a = Quissaquina Falls and b = Cabuta Falls. White bars on Kasai (C) represent possible natural barriers. x represents the locality of a specimen used in the genetic (barcoding) study.

Figure 3. TCS haplotype network showing the seven clusters identified from the COI haplotypes of the Parauchenoglanis ngamensis group. Each filled circle represents a haplotype. The size of each of those circles denotes the number of specimens sharing the same haplotype.The different colours used for the ellipses correspond to hydrographic sampling (sub)basins (Fig. 1) and the different genetic (barcoding) lineages as identified (Fig. 2). The number of crossbeams on the connecting lines between circles represents the number of mutations between these haplotypes.

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 9. Photograph of the typical colour pattern of a small-sized specimen of Parauchenoglanis dolichorhinus, SAIAB 85066, 52.4 mm SL, Kwanza River. 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 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.