Paramormyrops undetermined, Rich et al

Rich, Madeline, Sullivan, John P. & Hopkins, Carl D., 2017, Rediscovery and description of Paramormyrops sphekodes (Sauvage, 1879) and a new cryptic Paramormyrops (Mormyridae: Osteoglossiformes) from the Ogooué River of Gabon using morphometrics, DNA sequencing and electrophysiology, Zoological Journal of the Linnean Society 180, pp. 613-646 : 628-638

publication ID 10.1093/zoolinnean/zlw004

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Paramormyrops undetermined



( FIG. 12 View Figure 12 , TABLE 2)

Holotype: CUMV 98138, 175 mm SL, male, tag number JPS-1189, Gabon, Ogooué-Lolo, Ogooué River at Doumé , GPS coordinates: 0.84137°S, 12.96548°E, J.P. Sullivan & B. Sidlauskas, 17 September 2014. GoogleMaps

Paratypes (22): Ogooué River at Doumé (10) (0.843°S, 12.96°E): J.P. Sullivan GoogleMaps , 29 May 2011: CUMV 96811 View Materials , JPS- 1117, 120 mm SL ; AMNH 264795 View Materials , formerly CUMV 96811 View Materials , JPS- 1119, 110 mm SL ; MNHN 2016-0016 View Materials , formerly CUMV 96811 View Materials , JPS- 1120, 152 mm SL ; MRAC 2016- 010 View Materials -P-00001, formerly CUMV 96811 View Materials , JPS- 1122, 162 mm SL. (–0.841, 12.965): J.P. Sullivan & B. Sidlauskas GoogleMaps , 17 September 2014: CUMV 98129 View Materials , JPS- 1179, 121.5 mm SL ; AMNH 264796 View Materials , formerly CUMV 98132 View Materials , JPS- 1183, 126 mm SL ; MNHN 2016-0017 View Materials , formerly CUMV 98133 View Materials , JPS- 1184, 125.5 mm SL ; MRAC 2016-010 View Materials -P-00002, formerly CUMV 98141 View Materials , JPS- 1198, 137 mm SL ; CUMV 98142 View Materials , JPS- 1199, 137.5 mm SL ; AMNH 264797 View Materials , formerly CUMV 98144 View Materials , JPS- 1202,133 mm SL .

Upper Ogooué River (12) Under bridge near Franceville (1.637°S, 13.530°E) C.D. Hopkins et al., 7 August 1999. (9): AMNH 264798 View Materials , formerly CUMV 80463 View Materials , tag no. 3465, 7 August 1999 ; MNHN 2016-0018 View Materials , formerly CUMV 80463 View Materials , tag no. 3466, 132 mm SL ; MRAC 2016-010 View Materials -P-00003, formerly CUMV 80463 View Materials , tag no. 3467, 157 mm ; CUMV 96850 View Materials (6, specimen nos. JPS- 1095, JPS-1099 = AMNH 264799 View Materials JPS-1102, JPS-1103, JPS-1104, JPS-1105) 116–137 mm SL, J.P. Sullivan, 27 May 2011 .

Ogooué River, 30 minutes downriver from bridge near Franceville (1.603°S, 13.529°E): 14 August 1999. (3); MNHN 2016-0020 View Materials , formerly CUMV 80507 View Materials , tag no. 3667, 157 mm SL .; CUMV 80507 View Materials , tag no. 3671, 187 mm SL ; CUMV 80507 View Materials , tag no. 3720, 139 mm SL .

Non-type specimens used for phylogenetic analysis: Okano River near Mitzig (0.80983°N, 11.64633°E): AMNH 231500 View Materials (specimen no. 4149, referred to as B. cf. curvifrons in Sullivan et al., 2004), J.P. Sullivan et al., 2001-08-17 GoogleMaps .

Non-type specimens used for analysis of EODs: Doumé rapids, left bank of Ogooué River (0.841° S, 12.965° E): J.P. Sullivan, 16 September 2014: CUMV 98092 View Materials (1, specimen no. JPS-1176) 154 mm GoogleMaps

SL, EOD no. 197457. J.P. Sullivan, 17 September 2014: CUMV 98127 View Materials (1, specimen no. JPS-1177) 162 mm SL, EOD no. 197458. CUMV 98128 View Materials (1, specimen no. JPS-1178) 147 mm SL, EOD no. 197459. CUMV CUMV 98143 View Materials (1, specimen no. JPS-1200) 150 mm SL, EOD no. 197481 .

Sébé River, left bank rocks below bridge (0.93442°S, 13.35777°E): J.P. Sullivan, 20 September 2014: CUMV 98261 View Materials (1, specimen no. JPS-1217) 111 mm SL, EOD no. 197494. CUMV 98086 View Materials (1, specimen no. JPS-1222) 122 mm SL, EOD no. 197499. CUMV 98087 View Materials (1, specimen no. JPS-1224) 135 mm SL, EOD no. 197501. CUMV 98088 View Materials (1, specimen no. JPS-1225) 147 mm SL, EOD no. 197502. CUMV 98089 View Materials (1, specimen no. JPS-1228) 152 mm SL, EOD no. 197505. CUMV 98090 View Materials (1, specimen no. JPS-1229) 177 mm SL, EOD no. 197506. J.P. Sullivan, 22 September 2014: CUMV 98077 View Materials (1, specimen no. JPS-1241) 136 mm SL, EOD no. 197518. CUMV 98080 View Materials (1, specimen no. JPS-1242) 133 mm SL, EOD no. 197519. CUMV 98081 View Materials (1, specimen no. JPS- 1243) 146 mm SL, EOD no. 197520. CUMV 98078 View Materials (1, specimen no. JPS-1244) 141 mm SL, EOD no. 197521. CUMV 98079 View Materials (1, specimen no. JPS-1245) 146 mm SL, EOD no. 197522 GoogleMaps .

98130 (1, specimen no. JPS-1182) 132 mm SL, EOD no. 197462. CUMV 98131 (1, specimen no. JPS-1182) 163 mm SL, EOD no. 197463. CUMV 98134 (1, specimen no. JPS-1185) 176 mm SL, EOD no. 197466. CUMV 98135 (1, specimen no. JPS-1186) 162 mm SL, EOD no. 197467. CUMV 98136 (1, specimen no. JPS-1187) 165 mm SL, EOD no. 197468. CUMV 98137 (1, specimen no. JPS-1188) 144 mm SL, EOD no. 197469. CUMV 98139 (1, specimen no. JPS-1191) 116 mm SL, EOD no. 197472. CUMV 98140 (1, specimen no. JPS-1197) 145 mm SL, EOD no. 197478.

Diagnosis: Paramormyrops ntotom sp. nov. is distinguished from all other Lower-Guinea Paramormyrops by a combination of morphological and electrical characteristics: 5 teeth in upper-jaw, 6 in lower; 12 circumpeduncular scales; ‘V’-shaped snout profile viewed from above, snout angle 38–50° ( Fig. 5D View Figure 5 ), corresponding to an interorbital width 0.8–1.05 times the snout length; BD 14.9–18.1% SL, 81–91.6% of BD at urogenital pore ( Fig. 5E View Figure 5 ); eye diameter 12.4–14.7% HL measured to end of opercular bone ( Fig. 5F View Figure 5 ); snout length 23.8–28.3% HL; ratio of HL to depth (HLx/ HDx measured from radiographs) 1.25–1.40 ( Fig. 4A View Figure 4 ); HL 20.4–24.6% SL; EOD waveform with two phases, head positive then negative, duration 4.78 ± 1.10 ms with a corresponding peak power spectral frequency, 265 ± 67 Hz; electric organ composed of type NPp electrocytes ( Sullivan et al., 2002).

Comparison with other Paramormyrops: With its 5/6 teeth, 12 circumpeduncular scales and sharp snouts, P. ntotom sp. nov. differs from all other described Paramormyrops except P. curvifrons and P. sphekodes . We treat both of these in turn.

Four morphological characters distinguish P. ntotom sp. nov. from P. curvifrons . (1) ratio of HL to SL shorter in P. ntotom sp. nov. compared with P. curvifrons ( Fig. 5A View Figure 5 ); (2) slight concave depression in the forehead in advance of the orbit and a relatively compact snout compared to P. curvifrons which has a longer snout, downward sloping, often with a slightly protruding chin and upper lip; (3) shorter prepectoral distance relative to predorsal distance ( Fig. 5B View Figure 5 ); (3) snout angle greater in P. ntotom sp. nov. than P. curvifrons ( Fig. 5D, G View Figure 5 ) and (4) the HD relative to HL greater in P. ntotom sp. nov. than P. curvifrons ( Fig. 5C View Figure 5 ).

EOD duration slightly longer in P. ntotom sp. nov. compared with P. curvifrons , with extensive overlap ( Fig. 15 View Figure 15 ). Both species have type NPp electrocytes in the electric organ and both exhibit sex differences in EOD duration ( Table 3, Fig. 15 View Figure 15 ). Although these two species have overlapping EOD types, our collections indicate they are not anywhere sympatric. Paramormyrops curvifrons is known only from the Ivindo River in Gabon, while P. ntotom sp. nov. is known only from the Ogooué ( Fig. 10 View Figure 10 ).

Paramormyrops ntotom sp. nov. differs from P. sphekodes in the six following morphological characters: (1) larger overall size at sexual maturity ( Fig. 2 View Figure 2 ); (2) head more elongate and less rounded ( Fig. 4 View Figure 4 ); (3) snout reduced ( Fig. 3 View Figure 3 , Fig. 5G View Figure 5 ); (4) larger caudal peduncle depth to length ratio ( Fig. 3 View Figure 3 , Table 2); (5) the smaller eye diameter relative to HL, HLBO ( Fig. 5F View Figure 5 , Table 2); and (6) the greater EOD duration ( Figs 2 View Figure 2 , 14 View Figure 14 ).

When alive, P. ntotom sp. nov. is most easily distinguished from P. sphekodes by its longer EOD duration and a correspondingly lower peak spectral frequency ( Table 3, Figs 8 View Figure 8 , 14 View Figure 14 , 15 View Figure 15 ). The EODs of P. ntotom sp. nov. and P. sphekodes also differ in shape, with the width of first and second phase being equal for P. ntotom sp. nov., while W1 is longer than W 2 in P. sphekodes ( Fig. 15 View Figure 15 ). Living specimens of these two species also differ in coloration. Dorsal and anal fin pigmentation tends to be darker in P. ntotom sp. nov. than P. sphekodes , and the ground color of the skin tends to be darker chocolate brown compared to yellow brown in P. sphekodes ( Fig. 7 View Figure 7 ).

Description: Photos and radiograph of the holotype are shown in Fig. 12 View Figure 12 . Table 2 summarizes morphometric ratios and meristics for it and 22 paratypes. Figure 13 View Figure 13 shows five live specimens photographed in the field.

A large-bodied Paramormyrops , largest female, 137.5 mm SL (CUMV 98142, #JPS-1199), the largest male, 183 mm SL (CUMV 80507, #3671). Body laterally compressed with maximum width at opercular bones, 8.43–10.42% SL. Viewed laterally, BD increases gradually from base of the pectoral fin to its maximum at origin of the anal fin. BD at pectoral fin, 14.9–18.1% SL, BD at urogenital pore (BDUGP) 16.7–21.5% SL: the ratio of these two depths, 0.819 –0.916, reflects the slight increase posteriorly compared to P. sphekodes ( Table 2). BD decreases from origin of dorsal and anal fins to caudal peduncle. Caudal peduncle length 15.8– 19.4% SL, slightly deeper at origin than centre, CPD 26.1–33.7% CPL. Lobes of caudal fin rounded.

Lateral head profile straight and downward sloping from a point half way between opercular opening and tip of the snout, slightly concave above the eye in some specimens. Head and snout ‘V’-shaped when viewed dorsally ( Figs 9D View Figure9 and 15 View Figure 15 ), snout angle, 38–50° intermediate between that of P. curvifrons and P. sphekodes ( Fig. 5D, G View Figure 5 , Table 2). HL, 19.6–24.6% SL, similar to P. sphekodes , but shorter than P. curvifrons ( Fig. 5A View Figure 5 ). HD measured from external landmarks 64.8–79.8% HL, or HL/HD = 1.13–1.35. When measured from radiographs, HLx/HDx = 1.25–1.38, non-overlapping with P. sphekodes ( Fig. 4 View Figure 4 ). HW 38.3–46.9% HL. In lateral view, snout tip lies along mid-horizontal line. Teeth bicuspid, 5 (rarely 4) in upper and 6 in lower jaws.

Mouth small, rictus directly beneath nares. Chin slightly swollen below gular region, not extending beyond snout. Eye small, ED 10.6–15.0% HL ( Fig. 5F View Figure 5 ). Eye socket forms light ring around dark eyeball, with gold iris and dark centre. IOW 22.4–31.4% HL. Anterior naris at about 1/3 distance from snout tip to eye, slightly below line drawn through centre of eye, posterior naris halfway between anterior naris and eye, level with lower margin of eye. Opercular opening begins anterior to base of pectoral fin. POL 62.8–68.1% HL.

Pectoral-fin origin beneath posterior terminus of opercular opening, slightly below mid-horizontal line, pectoral length 14.6–16.8% SL, 10–12 rays. Pelvic-fin origin at 34.6–38.8% SL, length 8.2–11.1% SL, positioned ventrally, 6 rays. Pre-dorsal distance 61.4–66.1% SL; anterior margin of dorsal fin gently convex, trailing margin concave in first third, remainder levels off at 1/2 DFH. Maximum DFH 59.0–83.2% DFL, 19–21 total rays. Anal-fin origin slightly anterior to dorsal-fin origin: dorsal-fin origin above seventh anal ray (fifth branched ray).

Anal fin mirrors general shape of dorsal fin, maximum height 50.4–71.8% AFL. In males, anterior AFR thickened and stiff, noticeable notch in body spanning anterior half of anal-fin base. Anal-fin base terminus directly beneath that of dorsal fin, rays 24–26. Lobes of caudal fin rounded, equal, slightly wider than caudal peduncle, deeply cleft, scaled at the bases.

Scales fine, cycloid, absent from head. Pierced lateral line scales 57–72, 9–12 scale rows between anterior base of dorsal fin and lateral line, 10–14 scale rows from pelvic fin to lateral line. Circumpeduncular scales 12.

Vertebrae: 41–44 total, 18 pre-caudal and 22–26 caudal.

The EODs of P. ntotom sp. nov. differ between males and females ( Figs 2 View Figure 2 and 14C View Figure 14 ) with a corresponding difference in EOD power spectrum ( Figs 2 View Figure 2 and 14E View Figure 14 ). EOD duration of males, significantly longer than that for females (Student’s t = 2.107, P <0.05, Table 3). Widths of the first and second peaks nearly equal in P. ntotom sp. nov. both for males and females ( Table 3) contrasting with P. sphekodes where the first peak is longer than the second, especially for males. Variation in EOD duration amongst male P. ntotom sp. nov. results from EOD elongation during male sexual maturation – only appearing in the larger males during the breeding season. Adult males and females recorded during the dry season have similar EODs, a common pattern among mormyrids studied in the laboratory ( Kirschbaum, 1984, 1987) and in the field ( Bass et al., 1983).

Coloration. All fins with lightly to heavily pigmented rays, membranes hyaline. No dark band bases of dorsal and anal fins. Body darker dorsally, lighter ventrally. When alive, tan to light chocolate brown body with olive accents on top of head, back and belly. Mouth, chin and sometimes gular region unpigmented, white to grey. Many small white pores (mormyromast and ampullary electroreceptors) visible on top of head and back, with fewer, large white pores (Knollenorgans) on head. Preserved specimens are uniform greyish-brown.

Electric organ discharge. EOD composed of biphasic pulses, head positive then negative, total duration, 4.79 ± 1.1 ms ( Fig. 14A, C View Figure 14 ; Table 3). Width, W1, of first peak 2.25 ± 0.429 ms, approximately equal to width of second peak ( Table 3). Power spectrum peak, 265 ± 67 Hz. Other quantitative measures in Table 3 and Fig. 14 View Figure 14 . Marked inflection point on first rising phase of EOD in advance of peak P1; first derivative of EOD with two positive peaks before P1 ( Fig. 14B View Figure 14 , arrows 1 and 2), contrasting with P. sphekodes , which lacks an inflection point and has but a single peak in the first derivative ( Fig. 8B View Figure 8 ). No head-negative peak in advance of P1 (see 20× expanded trace in Fig. 14A View Figure 14 ) as occurs in all mormyrids with Type Pa electrocytes (P enetrating stalks with a nterior innervation), indicating that electrocytes are type NPp (i.e. have N on- P enetrating stalks with p osterior innervation), the same as P. sphekodes (not shown).

Distribution: Paramormyrops ntotom sp. nov. is found in Gabon in the Ogooué River and some of its tributaries ( Fig. 10 View Figure 10 ). We have confirmed its presence in the lower Ogooué near Lambaréné, the Okano River near Mitzig, the middle Ogooué near Lopé and the upper Ogooué from Doumé to Franceville. This species is notably missing from the Ivindo River, a major tributary of the Ogooué to the North East of Gabon, connected to the Ogooué through a series of major waterfalls.

Etymology: The species name, ntotom is the word for mormyrid fish in the language of the Fang people from northern Gabon, Equatorial Guinea and southern Cameroon.


Cornell University Museum of Vertebrates

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