Lamprologus tumbanus Boulenger, 1899

SCHELLY, ROBERT C. & STIASSNY, MELANIE L. J., 2004, Revision of the Congo River Lamprologus Schilthuis, 1891 (Teleostei: Cichlidae), with Descriptions of Two New Species, American Museum Novitates 3451, pp. 1-40 : 11-14

Lamprologus tumbanus Boulenger, 1899

Figures 9–11 , Table 2, Plate 1b

Lamprologus tumbanus Boulenger, 1899a: 116 , pl. 44, fig. 3 (Type locality: Bikoro, Lake Tumba).

Lamprologus congolensis tumbanus: Poll, 1933: 143 .

Lamprologus congoensis tumbanus: Colombe and Allgayer, 1985: 11 .

LECTOTYPE: MRAC 1041 , Bikoro, 00 ° 40 ̍ S, 18 ° 02 ̍ E, 1899, P. Delhez. (This specimen is here designated as the lectotype because it is the largest syntype and most closely resembles the original illustration.)

PARALECTOTYPES: MRAC 1042 , Bikoro, 00 ° 40 ̍ S, 18 ° 02 ̍ E, 1899, P. Delhez; BMNH 1899.11.27.63, Bikoro, 00 ° 40 ̍ S, 18 ° 02 ̍ E, 1899, P. Delhez .

ADDITIONAL MATERIAL EXAMINED: 4 specimens. Tondu, Lake Tumba (00 ° 50 ̍ S, 18 ° 07 ̍ E) MRAC 18019, H. Schouteden. Lake Tumba (00 ° 37 ̍ S, 17 ° 49 ̍ E // 01 ° 00 ̍ S, 18 ° 09 ̍ E) MRAC 100851–100853 (1 specimen c&s), 9/29/1955 – 9/30/1955, G. Marlier .

DIFFERENTIAL DIAGNOSIS: Lamprologus tumbanus differs from all other Congo River Lamprologus species in having 29–31 instead of 32 or more lateral line scales and 28–29 instead of 30 or more vertebrae and from all species save L. lethops in having four sensory pore openings on the lachrymal instead of five or six.

DESCRIPTION: Counts and measurements for 4 specimens, including lectotype and paralectotype MRAC 1042, are given in table 2. Achieves greatest relative body depth of the fluviatile Lamprologus (body depth 26.1– 28.9%, mean 27.5% SL), with a greatest body depth at about base of second dorsal fin spine. Head length 34.6–37.0%, mean 35.7% SL, proportionally greatest of all riverine lamprologines. Dorsal head profile rises straight at angle of about 45 °, angling sharply toward horizontal above orbit. Dorsal body profile gently convex, curving ventrally most steeply just anterior to caudal peduncle. Ventral body profile more or less straight, except for slight dorsal curvature anterior to caudal peduncle. Sexual dimorphism not obvious in limited material available.

Fins: Dorsal fin XVII–XVIII (mode XVII, lowest of riverine lamprologines) 7–9 (mode 9). Anal fin V 6–7. Filamentous extensions of dorsal and anal fins extend to midlevel of the caudal fin. Caudal fin large, rounded, and paddle­shaped, with 14 branched rays; often appears lance­shaped, subacuminate in preserved specimens. Pectoral fins short, not reaching vertical through anus. Pelvic fins relatively long (21.3–29.0%, mean 25.3% SL), reaching between anus and anal fin origin.

Teeth: Jaws isognathous, with sharply pointed unicuspid teeth. Six large canines implanted procumbently around jaw symphysis, with lateral teeth largest. Inner teeth are in 3–4 poorly defined rows of small, recurved, caniniform teeth, narrowing to single rows at about midpoint of dentigerous surface, and running most of length of dentary and premaxilla.

Gill Rakers: Moderately slender, elongate, non­denticulate. First arch ceratobranchial with 6–8 gill rakers (no rakers present on hypobranchial), often single raker at angle of arch, and 2–4 rakers along epibranchial of first arch.

Lower Pharyngeal Jaw: Wider than long, without interdigitation along ventral suture, and with 24 or so teeth in most posterior row. Teeth slender and beveled or slightly hooked; medial posterior teeth slightly more robust, but without stout molariform teeth.

Scales: Flank scales ctenoid and uniformly sized. Lateral line scales 29–31, lower than any other riverine lamprologine species. Upper and lower branches of lateral line do not overlap. In some canal­bearing lateral line scales posterior half of canal is open or unroofed, resulting in forklike appearance to canal. Cheek naked, opercle and subopercle with a few embedded scales. Gradual transition to small scales on belly and above anterior portion of lateral line. Nape and region just below dorsal fin origin scaleless. Dorsal and anal fins scaleless, caudal fin partially scaled.

Vertebrae: 28–29; 14 + 14 (1), 14 + 15 (4).

Additional Osteology (fig. 10): Infraorbital series comprised of broad, platelike lachrymal with 4 sensory canal openings and 2–4 tubular infraorbitals adjacent to lachrymal. Dermosphenotic absent. Supraneurals absent. Supraoccipital crest elevated and extends anteriorly in low frontal ridge to median coronal pore (NLF0). Elongate, paired, clublike processes serve as attachment area for supracarinalis anterior tendons to supraoccipital crest.

Coloration: Boulenger (1899a) described violet hues on the body, with scales trimmed in black and five black bars on the back, gray or blackish fins, and the opercle and cheek tinged with red. Preserved base body coloration yellowish brown. Individual flank scales with dark pigment distributed uniformly around exposed posterior margin, creating intersecting rows of thin, oblique bands of pigment that present appearance of chainlink fence or chain mail. Small, whitish maculae along interspinous membrane and between rays of dorsal, anal, and caudal fins. Dorsal, anal, and caudal fins with oblique black striations.

DIET: Gut short and simple, with length of about 50% of SL. Gut contents included small crustaceans, predominantly ostracods, along with insect parts, including a head that appeared to be from an adult dipteran.

DISTRIBUTION (fig. 11): Known only from Lake Tumba in the central Congo basin.

REMARKS: Although Poll (1933) and David and Poll (1937) considered tumbanus to be a subspecies of L. congoensis , a close examination of the material available at the time, along with some additional material collected since then, confirms tumbanus to be distinct and easily distinguishable from congoensis .

Figures

Plate 1. (a) Lamprologus congoensis, MRAC 118140–53, male, 104 mm SL; (b) Lamprologus tumbanus, MRAC 100851–53, male, 51 mm SL; (c) Lamprologus mocquardi, AMNH 5897, male, 78 mm SL; (d) Lamprologus werneri, MRAC 98158–92, male, 56 mm SL.

Fig. 9. Lamprologus tumbanus, male, 72 mm TL, modified from Boulenger (1899a).

Fig. 10. Lamprologus tumbanus, MRAC 100851–53: (a) neurocranium and first vertebra; (b) lachrymal and adjacent infraorbitals.

Fig. 11. Collection localities of Lamprologus tumbanus.