Parauchenoglanis megalasma, Sithole & Vreven & Bragança Tobias Musschoot & Chakona, 2024

Sithole, Yonela, Vreven, Emmanuel J. W. M. N., Bragança Tobias Musschoot, Pedro H. N. & 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, pp. 1-33 : 24-25

Parauchenoglanis megalasma sp. nov.

( Fig. 13; Table 3)

Common English name: Large spoưed grunter.

Common French name: Mâchoiron à large taches.

Holotope: SAIAB 118792 , 72.5 mm SL, Angola, Kasai sub-basin, main river above confluence with tributary 1, Luele (7°45 ʹ 20.1″S, 19°57 ʹ 19.4″E); DNA sample ES11-BT032: SB8992; collectors Ernst Swartz and Fenton P.D. Coưerill, 16 September 2011 .

Paratope (N = 1): Angola: SAIAB 235743 (ex SAIAB 118792 ), one, 66.9 mm SL, same collection details as the holotype; DNA sample ES11-BT016: SB8993 .

Diagnosis: Parauchenoglanis megalasma is distinguished from P. ahli , P. altipinnis , P. balaoi , P. buetikoferi , P. longiceps , P. monkei , P. pantherinus , and P. punctatus by the presence of vertical rows of blotches (vs. vertical rows of spots or bands in P. monkei and P. zebratus ). It is further differentiated from these species by a partly round snout (vs. bluntly triangular). Parauchenoglanis megalasma is distinguished from P. stiassnoae by truncated caudal fin (vs. rounded), dorsolaterally positioned eyes (vs. dorsally), and spoưed fins (vs. unspoưed pectoral, pelvic, and anal fins). Parauchenoglanis megalasma is distinguished from all other species except P. ernstswartzi by body with vertical rows of blotches with smaller blotches between them [ Fig. 13A; vs. body with vertical rows of spots or bars and spots between them in P. ngamensis ( Fig. 5A) and P. lueleensis ( Fig. 10A) or absent background spots in P. patersoni ( Fig. 11A), P. dolichorhinus ( Fig. 8A), P. luendaensis ( Fig. 14A), and P. chiumbeensis ( Fig. 15A)]. It is further differentiated from P. ernstswartzi by the vertical rows of blotches not extending onto adipose fin ( Fig. 13A; vs. rows extending onto adipose fin, Fig. 12A), eyes situated dorsolaterally (vs. eyes situated dorsally), and deeper body depth, 18.2%–19.9% SL (vs. shallow body depth, 15.0%–17.4% SL). Parauchenoglanis megalasma is further differentiated from P. luendaensis by spoưed head and fins (vs. unspoưed). It is further differentiated from P. luendaensis and P.chiumbeensis by relatively long predorsal length, 40.7%–41.9% SL (vs. shorter, 37.9%–40.1% SL in P. luendaensis and 35.6%–40.8% SL in P. chiumbeensis ). It is further differentiated from P. chiumbeensis by longer adipose fin, 35.6%–36.9% SL (vs. shorter, 26.0%–34.9% SL).

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, base of the dorsal fin slightly concave, straight from the adipose origin to caudal fin. Body depth highest at origin of dorsal fin. Ventral body profile slightly convex from lower jaw to pelvic fin origin, straight from pelvic origin to caudal fin. 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 origin 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 ray does not reach pelvic fin. Posterior margin of the pectoral-fin spine entirely serrated, and the anterior serrated towards distal end only. Caudal fin truncated.

Head moderately depressed. Snout profile partly round, on dorsal view ( Fig. 13B). Mouth subterminal. Lips fleshy. Eyes moderately large and situated dorsolaterally. Ŋree pairs of barbels, base thick and tips pointed. External mandibular longest, almost reaching the tip of pectoral-fin spine. Inner mandibular barbel shortest, reaching posterior edge of eye. Maxillary barbel surpassing the posterior edge of the eye but not reaching the base of pectoral-fin spine. Posterior nostril slits positioned about halfway between tip of snout and eye.

Colouration in alcohol: Body brown dorsally and laterally, and cream ventrally. Body with large black blotches about eye size forming six to seven vertical rows of large blotches, with those along the lateral line even bigger and thus larger than eye size. Blotches (smaller than those forming vertical rows) present in between vertical rows. Head brown with black blotches, smaller than those on body. Fins with black spots. Distal tip of fin rays with black markings. No distinct spots above gill opening, and two big spots present on caudal-fin base.Mandibular barbels (external and inner) with black spots, and maxillary barbel without spots.

Distribution: Parauchenoglanis megalasma is known from the Luele River, a right bank affluent of the Luxico River (Luchico sensu Poll 1967) and together (Luele and Luxico River) the right bank affluent of the Loange River, a less bank affluent of the Kasai immediately downstream of the Sankuru River, which is one of its right bank affluents.

Etomologo: Ŋe name ‘ megalasma ’ is derived from Greek ‘ mega ’ meaning large and ‘ melasma ’ meaning black spot, referring to the distinct large blotches along the lateral line present in this species.