Marcusenius pongolensis ( Fowler 1934 )

Maake, Pholoshi A., Gon, Ofer & Swartz, Ernst R., 2014, Descriptions of three new species of Marcusenius Gill, 1862 (Teleostei: Mormyridae) from South Africa and Mozambique, Zootaxa 3780 (3), pp. 455-480 : 473-475

Marcusenius pongolensis ( Fowler 1934)

Figure 2 a, Table 10

Gnathonemus macrolepidotus: Gilchrist & Thompson 1913: 330 –331, Tete, Lower Zambezi, Mozambique. Gnathonemus pongolensis Fowler, 1934: 419 , fig. 6.

Gnathonemus macrolepidotus: Crass 1960: 416 .

Marcusenius pongolensis Taverne 1971: 103 ; Kramer et al. (2007): 684, figs. 1D, 1M.

Holotype. ANSP 54950, 172.5 mm SL; Pongola River at Paulpietersburg district, South Africa, KwaZulu-Natal; not examined.

Material examined. Limpopo River system: SAIAB 188291, 11: 111–193 mm SL, Olifants River, below iron bridge, after Mogologolo village. SAIAB 188303, 4: 115–147 mm SL, Olifants River, above Loskop Dam in Aventuur, bridge on dirt road. SAIAB 188302, 20: 55–150 mm SL, Groot Letaba River, Broederstroom drift about 10 km from (south) of Tzaneen. SAIAB 188289, 24: 59–183 mm SL, Matlabas River, on road R510 bridge towards Thabazimbi.

Incomati River system: SAIAB 188297, 13: 46–136 mm SL, Crocodile River, below N4 bridge at Matsulu village. SAIAB 188300, 4: 129–189 mm SL, Omnia farm dam, Kopmeiden. SAIAB 54448, 12: 49–118 mm SL, Sabie River, above Hazyview. SAIAB 188280, 2: 77–107 mm SL, Sabie River at Hoxani area below dam. SAIAB 188279, 5: 61–158 mm SL, Sabie River, Sabana tributary at the back of the Sabie Adventures. SAIAB 188293, 2: 52–53 mm SL, Sabie River, Marite. SAIAB 188304, 11: 82–136 mm SL, Sand River.

Nkomati River system: SAIAB 69893, 2: 65.8–78.8 mm SL, Phophonyane River, Ntfonjeni Road. SAIAB 69907, 3: 113–252 mm SL, Mlumati River, Driekoppies Dam. SAIAB 69949, 7: 39.0– 73.5 mm SL, Nyonyane River, Sisa Ranch.

Pongola River system: SAIAB 79148, 5: 115.6–176.5 mm SL, Pongola River , bridge at road connecting Ndumo with Kosi Bay. SAIAB 188277, 2: 129–140 mm SL, Sitilo River, below bridge on N2 road to Jozini. SAIAB 188296, 16: 79–165 mm SL, Pongola River on R33 road to Paulpietersburg.

Kosi River system: SAIAB 88637, 2, Nkanini stream, below bridge just outside Manguzi on road to Mozambique. SAIAB 88633, 11: 98.8–147.7 mm SL, Mahlampane River, at Manguze village below bridge. SAIAB 88615, 11: 61.7–178.3 mm SL, Siyadla River, below the bridge just about one metre down and above the bridge.

Remarks. The measurements and meristic data of Kramer et al. (2007) ’s M. pongolensis were not always in agreement with our data ( Table 10 ), probably due to the inclusion of the Mhlatuze and Nseleni rivers as a southern population of M. pongolensis . Since these populations are now recognised as a new species, M. caudisquamatus , a new diagnosis for M. pongolensis is necessary.

Diagnosis and comparison. Marcusenius pongolensis is distinguished from other species in its more slender body (elongated, smaller body depth), with pD (37.1–39.8% SL), pA (40.8–42.2% SL) and LA (19.5–21.9% SL) ( Table 10 ), all shorter and non-overlapping with M. krameri ( Table 8 ), M. caudisquamatus ( Table 5) and M. lucombesi ( Table 9 ). Total vertebrae ranges between 42–43 vs 44 in other species; posterior total gill rakers (GRt) 13–14 vs 15 and 17 in M. caudisquamtus and M. krameri , respectively ( Table 6). Lateral line scales 70–73. Table 7 provides the range for counts of dorsal and anal fin rays, and circum-peduncular scales in M. pongolensis , M. krameri , M. caudisquamatus and M. lucombesi . Dorsal fin situated about three fourths of standard length from snout. Colour in life of M. pongolensis ranges from a homogeneous medium brown to grey-brown with yellowish to golden sheen, underside lighter, body has darker blotches on sides with yellowish fins ( Fig. 2 a). These diagnostic characters agree with those mentioned in Kramer et al. (2007) for the holotype of M. pongolensis . Marcusenius pongolensis is considered closest to M. macrolepidotus based on phylogenetic analyses of the mitochondrial cyt b dataset ( Fig. 4 ), and significant divergence from M. krameri , M. caudisquamatus and M. lucombesi (Table 2).

Electric organ discharge. Detailed in Kramer et al. (2007).

Distribution. Kramer et al. (2007) presumed that M. pongolensis was absent from the Limpopo River system. However, M. pongolensis was found in small numbers in the Olifants, Groot Letaba, and Matlabas rivers ( Fig. 1 ). Marcusenius pongolensis therefore occurs from the tropical sections of the Limpopo River system in the north to the Kosi River system in the south.

Biology and ecology. The biology and ecology of M. pongolensis is not well understood, but populations from an oligotrophic impoundment in Swaziland matured within the first year, at an estimated minimum length of 134 and 119 mm SL for males and females, respectively ( Booth & Khumalo 2010).

Figures

FIGURE 1. (a) Map of South Africa showing collection sites of Marcusenius pongolensis (black dots), M. krameri (pink diamonds) and M. caudisquamatus (red triangles). Names of major river systems are indicated in italics.

FIGURE 2. Photographs and radiographs of preserved specimens of four species of Marcusenius: (a 1 and a 2) M. pongolensis, SAIAB 188296, 165 mm SL, male, Pongola River; (b 1 and b 2) M. krameri, SAIAB 188295, 116.2 mm, male, holotype, Mogalakwena River; (c 1 and c 2) M. caudisquamatus, SAIAB 88684, 166 mm SL, male, holotype, Mhlatuze River; and (d 1 and d 2) M. lucombesi, SAIAB 73884, 74.0 mm SL, male, holotype, Lucombe River.

FIGURE 4. Maximum likelihood phylogram (lnL = 2537.87) based on mitochondrial cytochrome b sequences from the present study and GenBank using Marcusenius stanleyanus and Campylomormyrus compressirostris as outgroups. Values above the branches are bootstrap support based on 10 0 0 0 parsimony bootstrap replicates. Locality names, and SAIAB and Genbank accession numbers are indicated for each species individually.

Tables

TABLE 10. Basic statistics for morphological characters of Marcusenius pongolensis. See Table 1 for characters definitions.

Character Holotype* N	Mean/ Median	Min	Max	Std. Dev
SL, mm 172.5 mm 49	125.54	62.27	197	31.72
HL, mm 32.99 mm 49	25.5	12	36.6	5.92
Ratio of SL
HL 0.1913 49	0.2044	0.1797	0.2312	0.0118
vBD 49	0.2266	0.1942	0.2595	0.0163
mDB 0.1971 49	0.2298	0.2027	0.2496	0.0139
dAD 49	0.2421	0.2169	0.2628	0.0123
CPL 0.2029 49	0.2007	0.1660	0.2187	0.0100
PDL 0.6336 49	0.6330	0.6081	0.6646	0.0126
PAL 0.5936 49	0.6008	0.5600	0.6265	0.0154
pD 0.4017 49	0.3864	0.3706	0.3983	0.0067
pA 49	0.4152	0.4082	0.4216	0.0035
pPL 49	0.2207	0.2020	0.2325	0.0062
pVL 49	0.3917	0.3717	0.4123	0.0105
dVA 49	0.2169	0.1970	0.2422	0.0112
dPA 49	0.3886	0.3623	0.4213	0.0154
dPV 49	0.1830	0.1629	0.1994	0.0091
LD 0.1693 49	0.1748	0.1607	0.1925	0.0080
LA 0.2058 49	0.2152	0.1945	0.2198	0.0046
CPD/CPL 0.3800 49	0.3650	0.2868	0.4566	0.0392
Ratio of HL
HW 49	0.5854	0.5355	0.6758	0.0325
LSN 0.4667 49	0.4922	0.4513	0.5858	0.0260
IOW 49	0.4451	0.3801	0.5513	0.0369
ED 49	0.2052	0.1707	0.2525	0.0190
LP 49	0.7879	0.6161	0.9458	0.0786
Counts nD 21 49	Median 22	20	23	0.8118
nA 27 49	27	26	28	0.5654
SPc 16 49	17	16	17	0.5051
nTL 49	6	5	6	0.4657
nTU 49	5	4	5	0.3734
Total vertebrae 21	43	42	43	0.4629
LSS 30	71	70	73	0.9595
* Measurements taken from Kramer et al. (2007)