Mokele-mbembe Bichir

discussion

Discussion. With the description of Polypterus mokelembembe the number of currently valid Polypterus species and subspecies is increased to 13. Following inspection of hundreds of living Polypterus specimens that were commercially imported into Germany, Schaefer (2004), in his popular account on bichirs, recognized several more phenotypes within both the P. palmas and P. bichir complexes (P. ansorgii, P. lapradei, P. congicus are included in the latter group), which may well represent additional new species. This information, together with our cursory inspection of the large Polypterus collection in MRAC and preliminary molecular genetic data (Schliewen, unpubl.) suggest that a revision of Polypterus is overdue. We agree with Britz (2004) that such a revision should logically employ more novel characters than previously employed in Polypterus taxonomy. Polypterus mokelembembe has previously been identified as P. retropinnis, probably because of its high predorsal scale count, which separates these two species from most other Polypterus in central Africa. According to meristic data provided by Hanssens et al (1995) and Britz (2004), the only other Polypterus species with a comparati

Polypterus mokelembembe, a new species of bichir from the central Congo River basin (Actinopterygii: Cladistia: Polypteridae).

biology_ecology

Remarks. The largest known specimen (ZSM 33571 - 3) is a female, 235.2 mm SL, that was selected from a commercial import. The second largest specimen is a female, 220.7 mm SL, (MRAC 101372) with several hundred eggs averaging approximately 1.5 mm diameter in both ovaries. The species has reproduced once in captivity (P. Bartsch, pers. comm.).

Polypterus mokelembembe, a new species of bichir from the central Congo River basin (Actinopterygii: Cladistia: Polypteridae).

description

Description. See Figs. 1 - 3 for general appearance. Body subcylindrical and elongate, becoming increasingly laterally compressed over its caudal third. Greatest body depth on posterior half of body, approximately between first finlet and pelvic-fin base. Head slightly flattened dorsoventrally; mouth terminal; lips fleshy; snout comparatively acute and not broadly rounded as compared with all congeners except P. palmas polli. Anterior nostrils extending anteriorly as a nasal tentacle. Gill opening large, the opercular skin flap covering anterior portion of pectoral-fin base and extending from ventral midline to upper quarter of the body. Pectoral fins broadly rounded, almost circular, the posterior borders reaching the 8 th or 9 th scale row counted from behind the cleithrum but not reaching level of first dorsal spine. Six to eight dorsal finlets, of which the last one is continuous with the soft dorsal fin. Finlets overlapping when folded down. Membranous part of finlets supported by a strong and broad terminally bifurcated spine. Finlet membranes basally confluent with the following dorsal-fin spine base. Soft dorsal fin and caudal fin confluent. Caudal fin oval in shape or slig

Polypterus mokelembembe, a new species of bichir from the central Congo River basin (Actinopterygii: Cladistia: Polypteridae).

diagnosis

Diagnosis. Polyperus mokelembembe is distinguished from all other Polypterus species except P. retropinnis, P. teugelsi and P. palmas palmas by its high predorsal scale count (32 - 37 vs. 11 - 28). It differs from P. teugelsi by having 57 - 60 lateral-line scales (vs. 63 - 65), from Polypterus palmas palmas by a single large black blotch on pectoral fin base (vs. numerous small spots on posterior part of base), and from P. retropinnis in having a wider first dorsal finspine (6.4 - 8.1 vs. 4.6 - 6.1 % of HL), a shorter internostril distance (11.6 - 13.7 vs 14.3 - 18.0 % of HL), and fewer pectoral-fin rays (23 - 29 vs. 30 - 34) (Fig. 4). In addition, P. mokelembembe differs from all congeners by the presence of a few broad and ill defined lateral blotches or bars that converge dorsally to form broad saddles (vs. numerous black or brown bars or blotches, which may form a reticulate pattern but never converge dorsally to form a few broad saddles). There is no clear delimitation between the dark dorsolateral body coloration and the light coloured belly (vs. a clear border in P. retropinnis, P. teugelsi, P. palmas ssp., and P. weeksii).

Polypterus mokelembembe, a new species of bichir from the central Congo River basin (Actinopterygii: Cladistia: Polypteridae).