Tanganikallabes stewarti, Wright & Bailey, 2012, Wright & Bailey, 2012

Wright, Jeremy J. & Bailey, Reeve M., 2012, Systematic revision of the formerly monotypic genus Tanganikallabes (Siluriformes: Clariidae), Zoological Journal of the Linnean Society 165 (1), pp. 121-142: 132-136

publication ID

http://doi.org/ 10.1111/j.1096-3642.2011.00789.x

persistent identifier

http://treatment.plazi.org/id/03BD87B9-494D-F633-FF7C-F965FE9641CD

treatment provided by

Marcus

scientific name

Tanganikallabes stewarti
status

SP. NOV.

TANGANIKALLABES STEWARTI   SP. NOV.

( FIGS 3C View Figure 3 , 4B View Figure 4 , 11–13 View Figure 11 View Figure 12 View Figure 13 ; TABLES 3, 5)

Diagnosis: Tanganikallabes stewarti   sp. nov. is distinguished from all congeners by having an incomplete lateral line, which terminates at a vertical through a point approximately two-thirds of the distance along the anal fin base (versus lateral line reaching the caudal peduncle in T. mortiauxi   and extending much closer to the caudal peduncle in T. alboperca   sp. nov.; Fig. 11 View Figure 11 ), and by its relatively shallower body (body depth at anus 8.7–10.9% SL versus 12.3–17.2% SL in T. mortiauxi   and 11.7–14.6% SL in T. alboperca   sp. nov.).

Tanganikallabes stewarti   sp. nov. is further separated from T. mortiauxi   by its premaxillary toothpad shape (uniformly thin, broad crescent versus widest point anteroposteriorly thicker than the premaxillary toothpad in T. mortiauxi   ; Fig. 4 View Figure 4 ), lack of a free lower orbital margin, io-iv and the suprapreopercle consisting of multiple separate elements (versus a single element in T. mortiauxi   ; Figs 3 View Figure 3 , 5 View Figure 5 ), the extensions of the lateral ethmoid not reaching io-ii when viewed from above (versus nearly or completely overlaying io-ii in T. mortiauxi   ; Fig. 3 View Figure 3 ), its proportionally shorter prepelvic (35.7–39.2% SL versus 39.7–44.4% SL in T. mortiauxi   ) and preanal (42.4–44.8% SL versus 47.1– 51.7% SL) lengths, longer anal fin (anal fin base 54.1–58.9% SL versus 47.6–54.2% SL in T. mortiauxi   ). It can additionally be distinguished from T. alboperca   sp. nov. by its lack of a depigmented opercular margin, having longer pelvic fins (7.1–9.3% SL versus 6.0–7.7% in T. alboperca   sp. nov.), which reach beyond the origin of the anal fin when adpressed, proportionately longer pectoral fin spines (5.0–6.8% SL versus 3.6–5.3% SL in T. alboperca   sp. nov.), a shorter preanal length (42.4– 44.8% SL versus 45.2–49.0% SL in T. alboperca   sp. nov.), and a (generally) higher number of dorsal fin rays [72–79 (modally 76) versus 65–74 (modally 70) in T. alboperca   sp. nov.] and anal fin rays [63–69 (modally 65) versus 55–63 (modally 59) in T. alboperca   sp. nov.].

Description: Morphometric data are presented in Table 5, with the frequency distributions of selected meristic data presented in Table 3. Maximum TL 170 mm, SL 155 mm. Body elongate, moderately compressed posterior to origin of dorsal fin. Predorsal

Nasal barbel short; not extending to any aspect of opercular flap. Maxillary and lateral mandibular barbels extending to, or slightly beyond, tip of adpressed pectoral fin spine. Medial mandibular barbel extending slightly beyond lower opercular margin. All barbels smooth, with very narrow basal membrane.

Dorsal fin elongate, lacking spine, with 72–79 soft rays; origin located well behind vertical through posterior tip of adpressed pectoral fin; posterior margin not joined with caudal fin. Pectoral fin I,7–9: strong spine, well-developed venom glands present; spine approximately two-thirds the length of pectoral fin; posterior margin of spine with between zero and five very small, retrorse serrations. Adipose fin absent. Pelvic fin i,5: tip of adpressed fin reaches beyond origin of anal fin. Anal fin elongate, with 63–69 branched rays; posterior margin not joined with caudal fin. Caudal fin i,7,8,i: rounded.

profile convex, with distinct hump formed between origin of dorsal fin and basioccipital; only slightly convex from basioccipital to snout. Prepelvic profile slightly convex. Skin on body forming numerous vertical ridges and folds; extending onto and encasing all fins.

Head depressed and broad; skin thick; lateral cranial muscles hypertrophied, forming trough in centre of head over bones of skull. Snout short, with bluntly rounded margin when viewed dorsally; acute, narrow margin when viewed laterally. Anterior nostrils tubular; posterior nostrils poorly visible, located at posterior base of nasal barbel. Opercular flap extending over base of pectoral fin spine. Eye small, located dorsolaterally; circular; lacking free margin. Interorbital area broad, flat.

Mouth terminal; lips narrow and papillate; jaws equal, or upper jaw slightly longer. Mandibular, premaxillary, and vomerine teeth pointed, unicuspid, arranged in multiple transverse rows. Toothpads granular in appearance because of embedding of teeth in fleshy pad for most of their length. Mandibular toothpad wide, crescentic. Premaxillary toothpad broadly curved, rectangular, noticeably wider than vomerine toothpad. Vomerine toothpad located immediately posterior to premaxillary; narrow; broadly curved; crescentic.

Coloration in alcohol: Dorsum and flanks brown to dark brown, with ventral surfaces slightly lighter, although less so than in other Tanganikallabes species.   Some specimens (including holotype) show marbled appearance, with randomly arranged regions of lighter and darker coloration; other specimens uniform in dorsum and flank coloration ( Fig. 12 View Figure 12 ). Maxillary barbels uniformly brown, sometimes with slightly lighter pigmentation near tips. Nasal and mandibular barbels brown on proximal half, with distal portions becoming noticeably lighter. All rayed fins uniformly brown, with distinct, thin, white margin in smaller individuals.

Distribution: Most collections come from the northern part of Lake Tanganyika ( Fig. 13 View Figure 13 ), although a single collection from the southern Zambian coastline indicates that T. stewarti   sp. nov., like the other two known Tanganikallabes species   , has a lakewide distribution.

Habitat: Habitat details for this species are absent for the collections examined. It likely to inhabit rocky bottoms, over a range of depths, as is the case for T. mortiauxi   .

Diet: The stomach of the single specimen examined (UMMZ 196154) contained only the eggs of unidentified fish species.

Etymology: The specific epithet of this species is a patronym in honour of American ichthyologist Donald J. Stewart, who collected the holotype and other material used in the description of this species, as well as assisting in the collection of much of the type series of T. alboperca   sp. nov.

Material examined: Holotype: UMMZ 249379 View Materials (155 mm SL), between Mutumba and Magara among rocks, 3°40′S, 29°20′E, Burundi, Lake Tanganyika , X.1973 GoogleMaps   . Paratypes: UMMZ 196154 View Materials (3 alc, 1 c&s; 48–87 mm SL), collection data as for holotype GoogleMaps   ; SAIAB 86970 View Materials (1 alc; 131 mm SL), Chimba, 08°25.27′S, 30°27.44′E, Zambia, Lake Tanganyika , 07.III.2004 GoogleMaps   ; MRAC 130959–130970 View Materials (8 alc; 83–147 mm SL), Kalungwe , Lake Tanganyika, 11.VII.1961   ; MRAC 130828–130832 View Materials (5 alc; 68–113 mm SL), Luhanga , Lake Tanganyika, 7.VII.1961   ; MRAC 94662 View Materials (1 alc; 112 mm SL), northern Lake Tanganyika (no additional collection data)   ; MRAC 125723–125725 View Materials (3 alc; 81–109 mm SL), Kalungwe , Lake Tanganyika, 11.II. 1959   ; MRAC 130972–130974 View Materials (3 alc; 103–146 mm SL), Kalungwe , Lake Tanganyika, 13.VII.1961   ; MRAC 130769–130771 View Materials (3 alc; 77–100 mm SL), Mbemba , Lake Tanganyika, 10.VII.1961   ; MRAC 94670 View Materials , 94671 View Materials (2 alc; 78–131 mm SL), Luhanga , Lake Tanganyika, 29.VII.1954   .