Lamprologus symoensi Poll, 1976

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 : 22-26

Lamprologus symoensi Poll, 1976

Figures 18–20 , Table 5, Plate 2a

Lamprologus symoensi Poll, 1976: 110 , fig. 65 (Type locality: Lufira River at Kilwezi, Upemba National Park).

HOLOTYPE: MRAC 79001.6283 , Kilwezi, Lufira River , 09 ° 06 ̍ S, 26 ° 46 ̍ E, 8/10/48, G.­ F. de Witte.

PARATYPES: MRAC 79001.6284–6285 , 8/ 30/48, G.­F. de Witte ; IRSNB 26.832.722 , 8/ 10/48, G.­F. de Witte ; IRSNB 26.832.723 , 8/ 30/48, G.­F. de Witte. All from Kilwezi, Lufira River , 09 ° 06 ̍ S, 26 ° 46 ̍ E.

ADDITIONAL MATERIAL EXAMINED: 6 specimens. Kaolia (Kisale) (08 ° 13 ̍ S, 26 ° 29 ̍ E) MRAC 71435–71440 (2 specimens c&s), B. Dewit .

DIFFERENTIAL DIAGNOSIS: Lamprologus symoensi is distinguished from all other Congo River Lamprologus species save L. lethops by its irregularly sized flank scales, among which clear parallel rows are not apparent, and a scaleless patch on the head extending posteriorly well beyond the dorsal fin origin. The presence of fully developed eyes and a much greater BD as a percentage of SL (22.5–27.4% vs. 17.9%) make L. symoensi easily distinguishable from L. lethops .

DESCRIPTION: Counts and measurements of eight specimens, including holotype and paratypes (except for MRAC 79001.6285, which was not on loan), are given in table 5. Among the more deep­bodied fluviatile species of Lamprologus (body depth 22.5– 27.4%, mean 25.4% SL). Greatest body depth at dorsal fin origin. Head length 28.2– 33.0%, mean 31.3% SL. Head profile rises straight at angle of about 40 °, with more or less obvious angle above orbit, behind which dorsal profile is gently convex, becoming straight along caudal peduncle. Ventral body profile approximately straight, inclining posterodorsally just anterior to caudal peduncle. Sexual dimorphism not apparent in small number of specimens available for study.

Fins: Dorsal fin XIX–XXI (mode XX) 6– 8 (mode 8). Anal fin VI–VIII (mode VI) 5– 6 (mode 6). Spines in both fins gradually increasing in length posteriorly. Dorsal and anal fins relatively short, only reaching to base of caudal fin. Caudal fin large, rounded, and paddle­shaped, with 14 branched rays; often appears lance­shaped, subacuminate in preserved specimens. Pectoral and pelvic fins short, not reaching vertical through anus. Pelvic fin length 20.4–25.8%, mean 23.1% SL. Second ray of pelvic fin is longest in fin in both sexes.

Teeth: Jaws isognathous, both outer and inner row teeth unicuspid and sharply pointed. Single series of 6–8 greatly enlarged, recurved, procumbent canines situated anteriorly on premaxilla, with 6 such canines on dentary; lateral­most canines considerably larger than inner canines. Inner teeth in 4–5 poorly defined rows of tightly packed, small, recurved caniniform teeth anteriorly. Teeth thinning to single row of medium sized caniniform teeth posteriorly, and extending almost entire length of both dentary and premaxilla.

Gill Rakers: Slender, elongate, non­denticulate. Gill rakers numbers 5–6 along ceratobranchial of first gill arch (no rakers present on hypobranchial), typically with single raker in angle of arch, and 2 rakers along first epibranchial.

Lower Pharyngeal Jaw: Lower pharyngeal jaw wider than long, with no interdigitation along ventral suture. Usually 20 teeth in posterior most tooth row; posterior row teeth somewhat enlarged, especially medially, but not molariform. Remaining teeth slender, beveled, or bluntly hooked.

Scales: Flank scales ctenoid and variable in size, presenting jumbled pattern with parallel oblique scale rows mostly obscured. Lateral line scales 35– 42. Lateral line branches fragmented to varying degrees by intervening scales lacking canals. Upper and lower branches of lateral line non­overlapping, separated by about 5 unpored scales. Cheek naked, subopercle naked, opercle with few scales. Gradual transition to uniformly small scales on belly and above lateral line to about middle of dorsal fin base. Nape scaleless, with scaleless patch between lateral line and dorsal fin extending below dorsal fin to about fourth spine or further posteriorly. Dorsal and anal fins scaleless. Small scales occur over most of caudal fin.

Vertebrae: 31–33; 13 + 19 (1), 14 + 17 (2), 14 + 18 (3), 14 + 19 (2).

Additional Osteology (fig. 19): Infraorbital series comprised of broad, platelike lachrymal with 5 sensory canal openings and single tubular infraorbital adjacent to the lachrymal. Dermosphenotic absent. Presence of single supraneural polymorphic. Supraoccipital crest low and poorly developed. No frontal ridge extending to median coronal pore (NLF0).

Coloration: Live coloration unknown. Preserved coloration brownish, with 5–6 dark vertical bars faintly visible on flanks. Dorsal fin, posterior edge of caudal fin, anal fin, and pelvic fins darker than base body coloration. Maculae not apparent in fin membranes of preserved specimens.

DIET: Gut short and simple, with length about 70% of SL. Perhaps benthic macrophage; gut contents include disarticulated insect parts and fine gravel.

DISTRIBUTION (fig. 20): Known only from Upemba Lakes region of the upper Lualaba: Lake Kisale and the Kilwezi River.

50249: lachrymal and adjacent infraorbitals.

REMARKS: Lamprologus symoensi , like L. lethops , exhibits a characteristic flank squamation pattern, in which scales are irregularly sized and do not form easily recognizable parallel oblique rows.

Figures

Plate 2. (a) Lamprologus symoensi, paratype, MRAC 79001.6284–85, female, 46 mm SL; (b) Lamprologus lethops, holotype, MCZ 50248, male, 26 mm SL; (c) Lamprologus teugelsi, n.sp., holotype, AMNH 233611, female, 60 mm SL; (d) Lamprologus tigripictilis, n.sp., holotype, AMNH 233609, male, 62 mm SL.

Fig. 18. Lamprologus symoensi holotype, MRAC 79001.6283, male, 53.5 mm SL, modified from Poll (1976).

Fig. 19. Lamprologus symoensi, MRAC 71435–40: (a) neurocranium and first vertebra; (b) lachrymal and adjacent infraorbitals.

Fig. 20. Collection localities of Lamprologus symoensi.