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 Author Sithole, Yonela National Research Foundation-South African Institute for Aquatic Biodiversity (NRF-SAIAB), Makhanda, South Africa & Department of Ichthyology and Fisheries Science, Rhodes University, Makhanda, South Africa y.sithole@saiab.nrf.ac.za Author Vreven, Emmanuel J. W. M. N. National Research Foundation-South African Institute for Aquatic Biodiversity (NRF-SAIAB), Makhanda, South Africa & Vertebrate Section, Ichthyology, Royal Museum for Central Africa (RMCA), Tervuren, Belgium Author Bragança, Pedro H. N. National Research Foundation-South African Institute for Aquatic Biodiversity (NRF-SAIAB), Makhanda, South Africa & Department of Ichthyology, American Museum of Natural History (AMNH), New York, United States of America Author Musschoot, Tobias Vertebrate Section, Ichthyology, Royal Museum for Central Africa (RMCA), Tervuren, Belgium Author Chakona, Albert text Zoological Journal of the Linnean Society 2024 2024-11-13 202 3 1 33 https://doi.org/10.1093/zoolinnean/zlae121 journal article 306549 10.1093/zoolinnean/zlae121 a27fb5d2-9a22-45eb-a672-f073e0455642 0024-4082 14504088 3C2308D-7334-412D-871F-DE1F17C38D0E Parauchenoglanis ngamensis ( Boulenger 1911 ) ( Fig. 5 ; Table 3 ) Auchenoglanis ngamensis Boulenger 1911 . Parauchenoglanis ngamensis ( Mo 1991 , Teugels et al. 1991 , Skelton 2001 , 2019 , Geerinckx et al. 2003 , 2004 , Ferraris 2007 , Retzer 2008 , Marshall 2011 , Bruton et al. 2018 ). Parauchenoglanis ngamensis ‘okavango–zambezi’ ( Sithole et al. 2023 ). Common English name: Zambezi grunter ( Skelton 2001 ). Common French name: Mâchoiron de la Zambezi . Holotype : BMNH 1910.5.31.35 , 184.5 mm SL, Botswana , Okavango Basin , near Lake Ngami (~ 20°23 ʹ 42.0″S , 22°55 ʹ 32.9″E ); collector R.B. Woosnam 1911. Non-type material (N = 62): Angola : RMCA _ Vert _P.161712−161713, two, 139.6–204.2 mm SL, upper Zambezi sub-basin, Lake Calundo ( 11°48 ʹ S , 20°52 ʹ E ); collector unspecified; 1964 . RMCA _ Vert _P.161715, one, 169.0 mm SL, upper Zambezi sub-basin, Lake Calundo ( 11°48 ʹ S , 20°52 ʹ E ); collector unspecified; 1964 . SAIAB 190829 , one, 41.1 mm SL, upper Zambezi sub-basin, Cuando Cubango , Jamba camp site 2 ( 17°32 ʹ 4.4″S , 23°11 ʹ 20.7″E ); collectors Nkosinathi Mazungula , Manuel Domingos and Francisco de Almeida ; 27 April 2013 . SAIAB 207888 , two, 24.0– 89.5 mm SL, Okavango Basin , Rio Comba (affluent of Lungwebungu ) Sassicola Village ( 13°08 ʹ 12.8″S , 19°01 ʹ 48.3″E ); collectors Paul Skelton , Ben C.W. van der Waal and Frowin Becker ; 22 April 2018 . SAIAB 203307 , one, 104.2 mm SL, Okavango Basin , Cuito , Samahamba Village ( 14°51 ʹ 17″S , 19°17 ʹ 11″E ); DNA sample PHS16-335: SB8972; collector Adjany Costa ; 1 March 2016 . SAIAB 101057 , two, 121.9–134.4 mm SL, Okavango Basin , Cuito , margins of main channel, protected cattle drinking area and swamp ( 17°2 ʹ 55.4″S , 19°32 ʹ 4.6″E ); collectors Roger Bills , Nkosinathi Mazungula and Manuel Domingos ; 17 July 2013 . SAIAB 203213 , four, 112.3–147.0 mm SL, Okavango Basin , Cunde Waterfall ( 13°46 ʹ 25.0″S , 18°45 ʹ 22.8″E ); collector Adjany Costa ; 2 March 2016 . SAIAB 186847 , three, 72.8–132.9 mm SL, Okavango Basin , Cuito , Cunavale bridge ( 15°10 ʹ 16.4″S , 19°11 ʹ 39.3″E ); DNA sample RB12-A155 : ANGFW201-12 ; collectors Roger Bills , Paul Skelton and Francisco de Almeida ; 18 May 2012 . SAIAB 203177 , one, 24.4 mm SL, Okavango Basin , Cuanavale Source Lake ( 13°05 ʹ 25.1″S , 18°53 ʹ 37.4″E ); collector Adjany Costa ; 28 February 2016 . SAIAB 186832 , four, 16.9– 53.1 mm SL, Okavango Basin , Luassingua River , 55 km east of Menongue , at road Menongue-Cuito Cuanavale ( 14°35 ʹ 24.2″S , 18°10 ʹ 14.4″E ); DNA sample RB12-A474 : ANGFW168-12 ; collector Roger Bills ; 17 May 2012 . SAIAB 202475 , one, 84.4 mm SL; Okavango Basin , Hippo camp ( 13°08 ʹ 29.0″S , 18°29 ʹ 08.0″E ); collector Adjany Costa ; 11 June 2015 . SAIAB 204028 , four, 46.2–111.6 mm SL, Okavango Basin , below the outlet of the Cuanavale Source Lake ( 13°05 ʹ 37.1″S , 18°53 ʹ 45.5″E ); collectors Ben C.W. van der Waal and Nkosinathi Mazungula ; 23 October 2016 . SAIAB 203160 , two, 36.6–45.2 mm SL, Okavango Basin , Kalva and Cuito Confluence ( 12°44 ʹ 55.6″S , 18°21 ʹ 15.6″E ); collector Adjany Costa ; 25 February 2016 . SAIAB 203267 , two, 104.6–113.7 mm SL, Okavango Basin , Cuito , Alexandra camp ( 14°24 ʹ 40.1″S , 18°56 ʹ 54.5″E ); collector Adjany Costa ; 26 June 2015 . SAIAB 186951 , two, 42.9 mm SL, Okavango Basin , Cuchi town , road bridge ( 14°38 ʹ 58.9″S , 16°54 ʹ 23.7″E ); collectors Roger Bills and Paul Skelton ; 21 May 2012 . SAIAB 190653 , three, 174.1–198.5 mm SL , upper Zambezi sub-basin, Cuando Cubango , Base-Rio campsite ( 17°34 ʹ 23.1″S , 23°15 ʹ 36.9″E ); collectors Nkosinathi Mazungula , Manuel Domingos and Francisco de Almeida ; 30 April 2013 . SAIAB 204289 , three, 36.3−125.9 mm SL, upper Zambezi sub-basin, Crossing on maintrack SW Cambuta ( 13°26 ʹ 48.4″S , 19°57 ʹ 50.5″E ); DNA sample ANG16-306 : SB 7581; collector Roger Bills ; 20 November 2016 . SAIAB 204017 , two, 62.2–74.1 mm SL, upper Zambezi sub-basin, Lungwebungu River near bridge ( 12°34 ʹ 54.5″S , 18°40 ʹ 09.5″E ); collectors Ben C. W. van der Waal and Nkosinathi Mazungula ; 20 October 2016 . SAIAB 204255 , one, 112.7mm SL, upper Zambezi sub-basin, Cuembe at road bridge ( 13°31 ʹ 35.1″S , 19°16 ʹ 47.6″E ); DNA sample ANG16-338 : SB7582; collector Roger Bills ; 19 November 2016 . Botswana : SAIAB 18928 , one, 44.8 mm SL, Okavango Basin , Lake Ngami , East shore ( 20°30 ʹ 0″S , 22°40 ʹ .1″E ); collector Mike N. Bruton ; 7 June 1980 . SAIAB 52432 , one, 149.1 mm SL, Okavango Basin , Shakowe Camp ( 18°25 ʹ 59.9″S , 21°54 ʹ 00.0″E ); collectors Roger Bills and P. Yose ; 26 May 1996 . Namibia : SAIAB 187013 , one, 40.3 mm SL, Okavango Basin , Popa , ( 18°07 ʹ 18.2″S , 21°35 ʹ 00.2″E ); DNA sample RB12-540 : ANGFW222-12 ; collectors Roger Bills and Paul Skelton ; 24 May 2012 . SAIAB 203080 , one, 102 mm SL, Okavango Basin , River dance camp ( 19°54 ʹ 52.4″S , 24°22 ʹ 50.2″E ); collector Adjany Costa ; 5 August 2015 . SAIAB 202381 , three, 31.6–145.7 mm SL, Okavango Basin , Carioo unloading camp ( 12°52 ʹ 31.0″S , 18°18 ʹ 6.0″E ); collector Paul Skelton ; 3 June 2015 . SAIAB 44835 , one, 104.6 mm SL, upper Zambezi sub-basin ( 17°28 ʹ 00.0″S , 24°17 ʹ 00.0″E ); collector C. Hay ; 1 May 1994 . SAIAB 85562 , one, 83.9 mm SL, upper Zambezi sub-basin ( 17°28.5 ʹ S , 24°14.9 ʹ E ); DNA sample RB08 ZaNam 281: SB7585; collector Roger Bills ; 29 September 2008 . Zambia : RMCA _ Vert _P.142057, one, 137.3 mm SL, upper Zambezi sub-basin, Chavuma , Balovale ( 13°5 ʹ S , 22°40 ʹ E ); collector G. Bell-Cross ; 1963 . RMCA _ Vert _P.142072-142073, one, 101.4 mm SL, upper Zambezi sub-basin, Monga ( 15°17 ʹ S , 22°50 ʹ E ); collector G. Bell-Cross ; 1964 . SAIAB 98049 , three, 57.2–131.8 mm SL, upper Zambezi sub-basin, Kalumbila stream on K Hill road ( 12°14 ʹ 34.4″S , 25°22 ʹ 43.2″E ); DNA sample JWH10-A162: SB7586; collectors Roger Bills and A. Bok ; 8 November 2010 . SAIAB 71358 , two, 88.7−105.8 mm SL, upper Zambezi sub-basin ( 15°11 ʹ 43″S , 22°55 ʹ 20″E ); collectors Denis Tweddle and Ben C.W. van der Waal ; 10 November 2002 . SAIAB 97996 , one, 22.8 mm SL, upper Zambezi sub-basin, Mupulumba Village at footbridge ( 12°02 ʹ 28.8″S , 25°25 ʹ 33.9″E ); collectors Roger Bills and A. Bok ; 4 November 2010 . SAIAB 71869 , one, 97.9mm SL, upper Zambezi sub-basin ( 15°22 ʹ 29″S , 23°12 ʹ 2″E ); collectors Denis Tweddle and Ben C.W.van der Waal ; 27April 2003 . SAIAB 85560 , one, 47.2 mm SL, upper Zambezi River , Katima Mulilo in front of Ben’s House ( 17°29 ʹ 11″S , 24°15 ʹ 25″E ); DNA sample RB08 ZaNam 187: SB8974; collector Roger Bills ; 29 September 2008 . SAIAB 98109 , one, 114.2 mm SL, upper Zambezi sub-basin, Enterprise mine camp ( 12°11 ʹ 29.3″S , 25°12 ʹ 31.8″E ); DNA sample JWH10-A076: SB7588; collectors Roger Bills and A. Bok ; 6 November 2010 . SAIAB 98168 , two, 52.5–89.6 mm SL, upper Zambezi sub-basin, Chisolo river above Enterprise camp on drilling road (west bank) ( 12°10 ʹ 31.8″S , 25°12 ʹ 54.8″E ); DNA sample JWH10-A156: SB7587; collectors Roger Bills and A. Bok ; 6 November 2010 . SAIAB 73614 , one, 137.2 mm SL, supper Zambezi sub-basin ( 13°25 ʹ 21″S , 24°19 ʹ 54″E ); collectors Denis Tweddle and Ben C. W. van der Waal ; 6 October 2003 . Table 2. Comparison of qualitative characters between the Parauchenoglanis ngamensis candidate species identified based on the COI sequence data and the two candidate species identified by the morphological data only.

Character	Clade 1	Clade 2	Clade 3	Morphological data only
P. ngamensis s.s.	P. ngamensis	P. ngamensis	P. ngamensis	P. ngamensis sp.	P. ngamensis sp.	P. ngamensis sp.	P. ngamensis sp.	P. ngamensis sp.
sp. ‘kwanza 1’	sp. ‘kwanza 2’ (= P.	sp. ‘kasai 1’	‘kasai 2’	‘kasai 3’ (= P.	‘kasai 4’	‘luenda’	‘chiumbe’ (= P.
(= P. patersoni )	dolichorhinus )	(= P. lueleensis )	(= P. poikilos )	ernstswartzi )	(= P.	(= P. luendaensis )	chiumbeensis )
megalasma )
Caudal fin	Round	Round	Round	Truncated	Truncated	Truncated	Truncated	Truncated	Truncated
Colouration
Body	Bars (<100 mm	Bars (<65 mm	Bars (<95 mm SL),	Spotted	Spotted	Blotches	Blotches	Spotted	Spotted
SL), spots	SL), spots	spots (>100 mm
(≥100 mm SL)	(>100 mm SL)	SL)
Back -	Numerous spots	Absent	Absent	One or two	Numerous spots	Vermiculated	Blotches	Absent	Absent
ground*	spots	pattern
Head	Numerous spots	Absent (<10 if	Absent (<10 if pre-	Absent (<10 if	Numerous spots	Blotches	Blotches	Absent	Faint spots
present)	sent)	present)
Head profile	Moderately de-	Moderately de-	Depressed	Moderately de-	Moderately de-	Moderately de-	Moderately de-	Moderately de-	Moderately
depressed	pressed	pressed	pressed	pressed	pressed	pressed	pressed
Snout profile	Bluntly triangular	Bluntly triangular	Bluntly triangular	Bluntly tri-	Bluntly tri-	Round	Partly round	Bluntly triangular	Bluntly triangular
angular	angular
Eyes profile	Dorsolateral	Dorsolateral	Dorsolateral	Dorsolateral	Dorsolateral	Dorsal	Dorsolateral	Dorsolateral	Dorsolateral

* Background = additional black spots between vertical rows of spots or blotches. Diagnosis: Parauchenoglanis ngamensis is distinguished from Parauchenoglanis ahli (Holly 1930) , Parauchenoglanis altipinnis ( Boulenger 1911 ) , P. balayi (Sauvage 1879) , Parauchenoglanis buettikoferi (Popta 1913) , Parauchenoglanis longiceps (Boulenger 1913) , P. monkei (Keilhack 1910) , Parauchenoglanis pantherinus (Pellegrin 1929) , 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 also further distinguished 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). It is further distinguished from P.ahli and P. punctatus by shorter barbels, with external mandibular barbel not reaching the distal tip of the pectoral fin (vs. barbels long, with external mandibular barbel reaching distal tip of pectoral fin or beyond). Parauchenoglanis ngamensis is distinguished from P. zebratus by broad humeral process clearly visible through the skin and presence of five to seven bars on small specimens (≤ 100 mm SL) and vertical rows of spots on larger-sized specimens [vs. broad humeral process embedded under the skin and four to five vertical rows of spots on small specimens (≤ 100 mm SL) and bars on larger-sized specimens]. Parauchenoglanis ngamensis is distinguished from P. stiassnyae by the presence of vertical rows of black spots interspaced by scattered smaller black spots (vs. irregularly scattered large blotches and absence of smaller spots on the flank). They are further distinguished by shorter barbels, external mandibular barbel not reaching the distal tip of the pectoral-fin spine in P. ngamensis (vs. longer barbels, external mandibular extending beyond tip of the pectoral-fin spine in P. stiassnyae ). 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. Parauchenoglanis ngamensis is distinguished from the other members of the P. ngamensis group, i.e. P. patersoni , P. dolichorhinus , P. luendaensis , and P . chiumbeensis , by the presence of scattered black spots in between the vertical rows of black spots (vs. absent). It is further distinguished from these species by heavily spotted head and fins (vs. unspotted head and fins in P . luendaensis ; few black spots or unspotted head and fins in P . patersoni and P. dolichorhinus , and head and fins with faint black spots in P. chiumbeensis ). Parauchenoglanis ngamensis is further distinguished from P . chiumbeensis and P. luendaensis by round caudal fin ( Fig. 5A ; vs. truncated, Figs 14A , 15A , respectively). Parauchenoglanis ngamensis is distinguished from P . ernstswartzi and P . megalasma by vertical rows of black spots ( Fig. 5A ; vs. vertical rows of black blotches, Figs 12A , 13A , respectively) and bluntly triangular snout ( Fig. 5B ; vs. round in P. ernstswartzi and partly round in P. megalasma , Figs 12B , 13B , respectively). It is further distinguished from P . ernstswartzi by eyes situated dorsolateral ( Fig. 5A ; vs. eyes situated dorsally, i.e. high on the head towards its upper edge, Fig. 12A ) and absence of black spots at the base of pectoral fin ( Fig. 5C ; vs. present, Fig. 12C ). Parauchenoglanis ngamensis is distinguished from P. lueleensis by presence of numerous black spots in between vertical rows ( Fig. 5A ; vs. one or two spots present in between vertical rows, Fig. 12A ). Finally, P. ngamensis is distinguished from P. poikilos by a rounded caudal fin ( Fig. 5A ; vs. truncated, Fig. 11A ) and the absence of crescent-shaped marking on the caudal-fin base ( Fig. 5A ; vs. present, Fig. 11B ). Table 3. Morphometrics and meristics of the Parauchenoglanis species (re)described in this study.The given range for a species also includes holotype and paratype(s).

P. ngamensis s.s. ( N = 63)		P. patersoni ( N = 14)		P. dolichorhinus ( N = 4)
Variables	Holotype	Range	Mean	Holotype	Range	Mean	Holotype	Range	Mean
Standard length (mm)	184.5	22.8–204.2	98.8	192.9	42.9–223.0	111.5	139.8	52.4–115.1	86.5
Body measurements (% standard length)
Preanal length	60.9	55.9–74.1	64.0	61.1	56.1–62.2	60.6	58.8	58.6–59.9	59.4
Prepelvic length	50.2	48.0–54.9	50.9	52.1	48.1–53.5	51.1	48.9	49.6–50.9	50.2
Predorsal length	38.8	36.0–42.7	39.7	38.3	36.8–42.1	39.6	37.1	37.2–39.8	38.1
Prepectoral length	27.4	25.6–31.2	28.4	26.3	26.7–32.5	28.7	28.1	26.8–28.5	27.6
Adipose fin length	33.5	28.7–41.0	33.5	34.1	31.6–38.8	34.8	32.7	32.8–34.7	33.9
Interdorsal-adipose distance	4.5	3.0–12.9	7.7	6.9	3.5–10.0	6.4	10.5	6.3–9.9	8.4
Dorsal fin base length	15.9	14.2–18.4	16.3	15.5	14.7–18.7	16.2	15.5	15.7–17.6	16.5
Dorsal fin length	15.2	13.5–25.1	19.9	16.2	15.3–21.0	18.4	16.2	15.5–21.1	17.8
Dorsal fin spine length	14.0	12.4–20.3	16.3	16.6	14.5–19.5	16.3	11.3	11.4–13.7	12.7
Pectoral fin length	17.1	15.9–24.0	20.0	18.4	14.0–22.4	19.1	18.5	16.1–21.2	18.8
Pectoral fin spine length	16.7	12.7–21.1	17.0	16.5	12.9–19.0	16.9	16.6	12.6–15.8	14.6
Pelvic fin length	13.1	11.6–17.5	15.1	15.0	12.2–14.9	13.4	14.5	11.6–14.8	13.3
Anal fin length	12.1	10.2–25.1	16.2	13.3	10.6–14.6	12.3	12.6	13.2–14.2	13.7
Interpectoral distance	14.7	15.9–25.0	19.7	18.4	17.0–23.8	20.2	18.2	17.4–17.8	17.6
Interpelvic distance	6.8	5.2–12.0	8.6	10.9	8.6–11.3	9.9	11.0	9.8–11.2	10.3
Maximum body depth	17.4	14.6–23.5	18.4	16.3	15.5–21.4	17.6	13.2	11.6–14.0	12.9
Pelvic body depth	16.5	9.3–21.0	14.6	13.1	11.3–16.6	13.0	9.2	8.7–9.3	9.1
Minimum caudal peduncle depth	11.0	8.4–13.6	11.2	11.7	9.9–12.1	11.1	9.7	10.0–11.8	10.9
Maximum caudal peduncle depth	14.5	12.3–17.9	15.5	17.0	11.3–16.6	13.7	15.4	14.0–14.4	14.3
Adipose fin-caudal fin interdistance	6.8	4.8–8.3	6.6	5.4	4.1–6.7	5.9	5.8	5.3–6.4	5.9
Anal fin-caudal fin interdistance	14.7	12.6–18.5	15.2	14.1	12.4–17.1	15.2	17.6	14.0–17.7	16.0
Adipose fin depth	4.6	4.6–8.2	6.4	7.7	5.8–8.5	7.3	4.9	5.0–6.2	5.6
Head length	34.3	30.6–35.5	33.0	32.6	30.2–34.9	33.1	33.6	32.5–32.7	32.6
Head measurements (% head length)
Postorbital head length	42.6	39.1–47.9	42.9	43.0	39.9–46.1	43.5	41.5	41.4–43.3	42.5
Preorbital head length	45.4	34.3–50.9	45.8	47.2	38.2–50.8	44.0	48.1	44.8–45.2	45.0
Head width	49.5	60.9–85.9	70.1	66.6	66.8–78.5	71.3	65.8	63.1–72.5	67.5
Orbital head width	54.3	52.2–69.1	60.0	57.0	57.5–64.2	60.4	49.4	49.4–57.6	54.0
Head depth	47.6	40.6–60.8	52.3	52.5	48.5–54.9	51.7	34.6	38.9–40.0	39.6
Orbital head depth	33.1	21.8–48.1	36.7	40.8	27.4–45.9	36.9	25.8	27.6–28.6	28.2
Snout depth	18.1	10.9–28.5	17.6	20.4	13.2–20.9	17.0	13.5	12.1–12.5	12.2
Maxillary barbel length	42.7	30.3–79.0	48.1	37.3	39.4–62.0	50.6	48.3	60.4–72.1	66.1

Table 3. Continued

P. ngamensis s.s. ( N = 63)		P. patersoni ( N = 14)		P. dolichorhinus ( N = 4)
Variables	Holotype	Range	Mean	Holotype	Range	Mean	Holotype	Range	Mean
External mandibular barbel length	81.2	48.6–110.1	85.3	86.0	76.7–118.2	93.0	86.3	99.5–118.1	106.0
Internal mandibular barbel length	44.4	31.0–55.8	43.5	37.8	36.1–58.3	45.2	35.3	40.7–52.7	45.8
Mandibular barbels interdistance	13.5	9.3–21.4	14.0	14.0	10.3–18.7	14.6	12.0	12.4–13.4	13.0
Interorbital distance	22.0	19.3–28.0	22.6	20.0	19.7–25.8	22.8	17.5	16.7–22.8	19.7
Anterior nostrils interdistance	9.4	7.6–20.2	13.0	9.5	13.7–20.3	16.8	10.5	7.2–17.6	13.4
Posterior nostrils interdistance	7.5	8.5–12.2	10.0	8.9	7.9–11.1	9.4	8.8	8.0–9.2	8.5
Supraoccipital process-nuchal plate interdistance	1.3	.9–7.2	2.7	1.3	1.4–6.7	3.6	6.7	4.0–6.8	5.9
Supraoccipital process-dorsal fin interdistance	18.1	13.9–23.2	17.9	18.2	10.2–21.2	15.1	14.0	9.2–15.0	13.0
Prehyoid length	15.4	7.9–21.7	15.7	20.4	10.3–25.8	16.0	20.8	15.5–21.0	18.3
Mouth width	41.7	27.6–66.6	46.6	45.7	40.2–61.2	46.9	47.6	44.0–54.4	48.9
Premaxillary toothplate width	9.5	8.7–19.4	12.2	11.4	9.1–13.2	11.3	12.0	8.8–15.8	11.5
Orbital diameter	13.1	11.4–24.5	16.5	15.5	14.2–19.7	16.9	15.7	16.4–19.5	17.5
Meristics	Median	Median	Median
No.of dorsal-fin rays	7	7–8	7	7	6–7	7	7	7	7
No.of anal-fin rays	10	8–11	10	11	10–11	10	8	9–10	9
No.of pectoral-fin rays	8	7–8	8	7	7	7	7	7	7
No.of pelvic-fin rays	6	6	6	6	6	6	6	6	6
No.of caudal-fin rays	18	15–18	17	18	15–17	17	14	15–16	15
No.of serrae anterior margin pectoral-fin spine	2	0–7	3	5	2–5	3	4	2–4	3
No.of serrae posterior margin pectoral-fin spine	18	4–19	12	17	7–16	9	15	8–10	9
Vertebrae	( N = 4)	( N = 4)	( N = 4)
No.of pre-anal vertebrae	15	15–17	15	16	16	16	15	15–17	15
No.of caudal vertebrae	20	19–21	19	20	19–20	19	20	19–21	20
Total Vertebrae	35	34–36	36	36	35–36	35.5	35	35–36	35.5

Table 3. Continued

P. lueleensis ( N = 14)		P. poikilos ( N = 2)		P. ernstswartzi ( N = 4)		P . megalasma ( N = 2)
Variables	Holotype	Range	Mean	Holotype	Paratype	Holotype	Range	Mean	Holotype	Paratype
Standard length (mm)	95.4	32.1–158.5	65.6	57.2	36.3	96.6	92.0–105.6	97.5	72.5	66.9
Body measurements (%standard length)
Preanal length	62.5	57.0–61.3	59.8	59.6	60.1	61.1	61.5–65.2	63.5	59.4	59.5
Prepelvic length	51.2	50.1–53.8	51.4	50.0	51.1	53.1	53.8–57.1	55.5	51.1	54.0
Predorsal length	39.8	39.4–42.0	40.7	39.2	38.4	40.1	39.1–40.5	40.0	40.7	41.9
Prepectoral length	30.0	28.5–30.9	29.8	31.4	30.6	29.0	30.3–31.8	31.0	28.6	30.4
Adipose fin length	36.7	32.5–39.7	36.9	36.0	36.6	35.3	33.2–35.7	34.4	36.9	35.6
Interdorsal-adipose distance	3.7	4.1–6.8	5.2	5.5	5.8	3.9	3.8–5.0	4.4	4.8	3.9
Dorsal fin base length	14.9	15.5–17.8	16.6	15.8	16.3	16.6	16.4–17.7	17.1	16.9	18.2
Dorsal fin length	17.5	14.5–23.4	19.3	19.4	17.6	19.1	16.4–19.9	18.6	22.9	21.4
Dorsal fin spine length	16.7	12.3–16.6	15.1	19.2	15.6	14.6	15.8–21.2	18.5	15.0	16.8
Pectoral fin length	20.8	19.2–22.5	21.5	21.8	20.5	22.5	15.7–22.0	19.1	21.9	21.6
Pectoral fin spine length	17.6	14.6–19.8	17.8	16.9	14.8	20.2	18.5–18.9	18.7	16.8	19.7
Pelvic fin length	16.0	11.8–17.3	15.4	16.6	13.4	15.9	15.0–16.1	15.6	15.3	15.6
Anal fin length	16.7	10.8–15.9	13.9	16.3	12.0	14.5	14.6–14.8	14.7	16.2	17.0
Interpectoral distance	18.9	18.8–22.5	20.5	18.4	21.0	19.9	19.8–20.6	20.2	18.8	21.9
Interpelvic distance	10.0	7.1–11.2	9.1	8.9	7.6	9.5	8.3–10.3	9.6	9.3	9.8
Maximum body depth	15.7	15.0–17.4	16.1	16.2	16.0	18.7	18.2–19.9	18.9	20.2	20.9
Pelvic body depth	12.1	8.8–14.3	10.8	11.9	11.4	14.3	14.2–16.9	15.4	14.3	12.8
Minimum caudal peduncle depth	12.2	10.6–13.0	11.6	11.2	10.4	12.3	13.4–14.6	13.9	13.1	13.4
Maximum caudal peduncle depth	14.7	11.1–16.0	13.9	13.9	13.5	15.1	14.9–15.2	15.1	15.5	14.9
Adipose fin-caudal fin interdistance	5.8	5.7–6.8	6.2	6.2	5.7	5.9	4.6–6.2	5.2	5.7	4.2
Anal fin-caudal fin interdistance	16.7	14.5–17.6	16.4	17.0	13.1	17.9	12.7–15.1	13.8	15.0	15.3
Adipose fin depth	7.6	6.1–8.1	7.0	6.4	6.1	7.3	7.3–7.5	7.5	7.3	7.8
Head length	36.0	31.8–35.7	33.9	35.6	35.0	33.2	34.9–35.3	35.1	34.8	35.5
Head measurements (% head length)
Postorbital head length	42.2	38.8–45.4	41.5	40.6	42.4	41.1	40.7–42.0	41.4	40.6	38.6
Preorbital head length	44.4	37.6–47.2	42.4	42.0	41.2	47.1	41.9–45.6	44.2	45.7	46.6
Head width	64.8	64.9–78.3	71.5	65.3	68.8	70.4	68.0–70.5	68.9	66.2	72.6
Orbital head width	54.5	54.3–64.2	59.6	50.3	56.3	62.5	61.4–61.7	61.5	58.2	59.6
Head depth	44.9	41.2–50.3	45.9	43.5	41.7	52.5	49.5–54.0	52.1	52.2	52.7
Orbital head depth	35.9	21.4–36.3	28.7	27.2	26.7	40.2	34.2–42.0	38.9	38.5	38.3
Snout depth	15.9	12.3–19.5	15.0	13.8	11.0	18.6	16.5–19.3	18.1	18.3	17.0
Maxillary barbel length	59.8	36.1–66.7	56.3	68.3	60.3	54.5	53.4–60.9	56.5	54.3	69.7
External mandibular barbel length	122.8	60.5–123.5	102.1	109.5	102.2	89.4	85.2–92.9	89.7	89.6	99.2

Table 3. Continued

P. lueleensis ( N = 14)		P. poikilos ( N = 2)		P. ernstswartzi ( N = 4)		P . megalasma ( N = 2)
Variables	Holotype	Range	Mean	Holotype	Paratype	Holotype	Range	Mean	Holotype	Paratype
Internal mandibular barbel length	50.9	35.8–52.6	44.2	45.6	53.0	60.2	52.8–57.4	55.5	53.8	60.3
Mandibular barbels interdistance	14.1	15.5–21.4	17.3	15.6	18.8	14.4	13.0–15.9	14.8	14.8	12.4
Interorbital distance	17.3	18.0–26.2	21.1	19.2	24.6	21.4	18.3–20.9	19.3	21.2	22.6
Anterior nostrils interdistance	13.3	15.7–21.7	18.0	18.1	17.8	19.1	15.1–18.2	16.7	20.0	22.0
Posterior nostrils interdistance	8.1	7.9–10.9	9.1	10.1	11.0	9.9	10.5–11.4	11.1	10.5	10.9
Supraoccipital process-nuchal plate interdistance	2.7	1.4–5.7	3.5	4.3	3.5	1.8	1.2–1.7	1.5	1.3	2.7
Supraoccipital process-dorsal fin interdistance	16.3	12.5–17.5	14.5	13.0	13.4	17.0	13.1–15.8	14.5	12.9	17.3
Prehyoid length	17.3	13.1–15.4	14.0	15.6	14.0	16.7	16.8–19.4	18.1	14.6	13.9
Mouth width	42.3	41.1–57.5	52.9	42.4	55.7	50.9	41.0–46.7	42.9	52.5	49.9
Premaxillary toothplate width	9.8	9.9–15.9	12.8	13.5	14.0	14.2	11.4–15.6	13.7	13.8	15.0
Orbital diameter	16.2	15.3–22.8	20.2	18.1	18.8	17.5	16.2–16.4	16.3	15.9	16.4
Meristics	Median	Median
No.of dorsal-fin rays	7	7–8	7	7	7	7	7	7	7	7
No.of anal-fin rays	9	9–11	10	9	10	10	9	9	9	9
No.of pectoral-fin rays	7	7–8	7	7	7	7	7	7	7	7
No.of caudal-fin rays	17	17–18	17.5	17	18	15	15–17	17	17	17
No.of pelvic-fin rays	6	6	6	6	6	6	6	6	6	6
No.of serrae anterior margin pectoral-fin spine	4	0–4	3	3	3	6	2-5	3.5	4	3
No.of serrae posterior margin pectoral-fin spine	14	8–18	9.5	9	6	15	13–15	14	10	10
Vertebrae	( N = 4)	( N = 2)	( N = 4)	( N = 2)
No.of pre-anal vertebrae	16	16–17	16.5	17	17	15	14–15	14	14	14
No.of caudal vertebrae	19	18–20	19	19	19	17	17–18	18	18	19
Total vertebrae	35	35–36	35.5	36	36	32	32	32	32	33

Table 3. Continued

P. luendaensis ( N = 10)		P. chiumbeensis ( N = 11)
Variable	Holotype	Range	Mean	Holotype	Range	Mean
Standard length (mm)	102.2	49.0–122.0	81.8	131.5	53.5–142.9	100.6
Body measurements (% standard length)
Preanal length	59.7	58.9–64.2	61.1	61.4	59.4–63.4	60.8
Prepelvic length	48.7	48.9–52.6	50.7	48.8	48.6–56.2	50.7
Predorsal length	38.5	37.9–40.1	39.2	36.7	35.6–40.8	38.3
Prepectoral length	26.8	26.2–29.5	27.7	26.8	26.7–29.5	27.8
Adipose fin length	33.6	29.5–38.6	33.8	30.4	26.0–34.9	31.1
Interdorsal-adipose distance	3.7	4.3–8.0	6.3	8.8	6.3–12.7	8.8
Dorsal fin base length	16.4	15.8–18.2	17.2	15.7	15.2–17.8	16.1
Dorsal fin length	17.0	17.4–24.2	20.6	18.5	17.3–20.9	19.7
Dorsal fin spine length	16.7	14.1–19.3	16.8	16.7	14.5–17.4	15.7
Pectoral fin length	18.5	16.4–22.6	20.0	21.5	19.8–23.0	21.0
Pectoral fin spine length	16.9	15.2–19.0	17.4	17.4	16.0–19.0	17.6
Pelvic fin length	15.1	14.6–19.3	17.2	13.7	13.6–18.8	16.7
Anal fin length	14.2	12.0–15.2	13.6	13.8	11.8–15.7	13.5
Interpectoral distance	18.9	17.3–21.1	18.5	16.9	15.8–20.4	17.4
Interpelvic distance	11.5	4.1–10.8	7.0	9.8	5.4–10.8	7.9
Maximum body depth	17.3	14.8–21.3	18.5	17.8	14.5–18.9	16.1
Pelvic body depth	13.2	12.6–18.7	15.7	14.1	12.0–16.0	14.3
Minimum caudal peduncle depth	12.7	10.9–13.0	11.9	11.1	9.8–12.5	10.9
Maximum caudal peduncle depth	14.9	12.5–15.6	14.3	14.0	12.2–14.7	13.8
Adipose fin-caudal fin interdistance	7.8	5.5–6.9	6.2	8.1	5.3–8.2	7.2
Anal fin-caudal fin interdistance	15.1	12.9–15.0	14.4	15.2	13.6–17.6	15.2
Adipose fin depth	6.5	6.4–7.7	6.9	6.2	5.1–6.8	6.1
Head length	34.2	31.0–34.5	32.9	32.9	30.9–34.5	33.1
Head measurements (% head length)
Postorbital head length	43.6	38.0–47.3	42.3	40.4	36.9–44.7	40.7
Preorbital head length	45.1	44.5–48.8	46.2	47.6	43.4–47.7	46.0
Head width	65.9	60.9–73.0	68.9	61.7	56.8–69.4	63.9
Orbital head width	58.7	58.5–67.4	62.8	54.3	55.1–63.7	56.9
Head depth	48.2	49.9–59.2	54.5	49.0	42.0–53.5	46.7
Orbital head depth	22.9	31.4–37.8	34.1	34.6	29.6–34.1	32.3
Snout depth	16.1	13.1–19.0	17.4	11.0	11.3–19.0	15.4
Maxillary barbel length	57.6	56.1–76.1	65.7	62.2	48.3–68.2	56.8
External mandibular barbel length	102.8	98.1–125.6	111.7	105.5	95.8–119.2	105.2

Table 3. Continued

P. luendaensis ( N = 10)		P. chiumbeensis ( N = 11)
Variable	Holotype	Range	Mean	Holotype	Range	Mean
Internal mandibular barbel length	48.0	40.0–56.6	51.9	42.5	36.8–49.0	43.4
Mandibular barbels interdistance	11.3	10.0–15.1	12.9	14.3	10.1–13.4	11.3
Interorbital distance	18.8	17.9–23.5	21.2	17.6	16.9–21.3	19.3
Anterior nostrils interdistance	16.8	10.2–19.4	14.3	14.1	12.5–16.9	14.1
Posterior nostrils interdistance	8.2	8.3–10.2	9.3	8.2	7.8–11.3	9.1
Supraoccipital process-nuchal plate interdistance	1.2	1.1–5.0	3.1	3.7	1.5–5.5	3.4
Supraoccipital process-dorsal fin interdistance	14.2	14.7–23.3	18.8	14.0	14.4–22.5	19.1
Prehyoid length	14.4	10.3–17.5	13.0	16.0	14.8–18.6	16.5
Mouth width	40.9	40.0–52.1	45.5	48.2	41.4–48.9	45.1
Premaxillary toothplate width	10.8	10.9–13.2	12.1	10.7	8.6–13.0	11.3
Orbital diameter	15.4	14.6–19.9	17.3	14.3	15.2–19.9	17.8
Meristics	Median	Median
No.of dorsal-fin rays	7	7	7	7	7	7
No.of anal-fin rays	10	8–10	9	10	8–10	9
No.of pectoral-fin rays	7	7–8	7	7	7	7
No.of pelvic-fin rays
No.of caudal-fin rays	17	17–18	17	17	17–17	17
No.of serrae anterior margin pectoral-fin spine	5	1–5	3	4	2–4	3
No.of serrae posterior margin pectoral-fin spine	14	9–14	12	15	8–16	12
Vertebrae	( N = 3)	( N = 4)
No. of pre-anal vertebrae	15	15	15	17	17–18	17
No.of caudal vertebrae	22	20–22	21	20	19–20	20
Total vertebrae	37	35–37	36	37	36–37	37

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, about straight from dorsal-fin origin to adipose-fin origin, and slightly directed downwards from adipose-fin origin to caudal-fin base. Body depth highest at origin of dorsal fin. Ventral body profile slightly convex from lower jaw to origin of pelvic fin, straight from pelvic fin to origin of anal fin, slightly concave from origin of anal fin to caudal-fin base. Caudal peduncle laterally compressed. Anus and urogenital opening positioned about halfway between pelvic- and anal-fin origins. Figure 6. Photographs of the different colour patterns identified within Parauchenoglanis ngamensis . A, small-sized specimen with bars (SAIAB 204289, 36.3 mm SL, Upper Zambezi River). B, smallto medium-sized specimen with spots surrounded by light brown shading (SAIAB 204289, 46.4 mm SL, Upper Zambezi River). Scale bar: 1 cm. Adipose fin longer than anal-fin base, originating anteriorly to anal-fin origin, between pelvic-fin base and anal-fin origin, and ending posteriorly to end of anal-fin base. Dorsal-fin origin anterior to pelvic-fin origin. Posterior edge of pectoral-fin rays does not reach pelvic fin. Dorsal and pectoral fins with strong spine. Posterior edge of pelvic-fin rays does not reach anal fin. Anterior margin serrated on the distal end and entire posterior margin of the pectoral-fin spine serrated. Caudal fin rounded. Head moderately depressed. Snout profile bluntly triangular, on dorsal view ( Fig. 5B ). Mouth subterminal. Lips fleshy. Eyes small and situated dorsolaterally.Three pairs of barbels, base thick and tips pointed. External mandibular barbel longest, almost reaching middle of pectoral-fin spine. Inner mandibular barbel shortest, reaching middle of eye. Maxillary barbel surpassing posterior edge of eye but not reaching the base of pectoral-fin spine. Posterior nostril slits positioned about halfway between snout tip and eye. Colouration in life: Overall body colouration yellow-brown and white ventrally. Body with scattered black spots, some arranged in a series of five to seven vertical rows along the body ( Skelton 2001: 212 ; Marshall 2011: 146 ; Bruton et al. 2018: 73 ). Colouration in alcohol: Body brown to light brown dorsally and laterally, and light brown to white ventrally. Body with five to seven black bars in small-sized specimens, and no black spots in between bars ( 22.8–46.4 mm SL; Fig. 6A ). Medium-sized specimens (50.0– 97.9 mm SL; Fig. 6B ) with black spots smaller than the eye diameter forming five to seven vertical rows, surrounded by light brown shade. Large-sized specimens have five to seven vertical rows of black spots, smaller than eye diameter ( 101.4– 204.2 mm SL; Fig. 5A ). Scattered black spots present in between vertical rows in medium- and large-sized specimens. Head brown or light brown, with scattered small black spots, i.e. smaller than those on body. Fins also with numerous black spots. Distal tips of fin rays with black markings except in small-sized specimens. Usually, one or two small black spots present above gill opening and one on midline of caudal-fin base. Barbels unspotted. Distribution: Parauchenoglanis ngamensis is known only from the Okavango and upper Zambezi (sub)basins in southern Africa ( Fig. 1 ). Etymology: Boulenger named the species after Lake Ngami, Botswana , where it was first recorded.