Tanganikallabes alboperca, 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: 129-131
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TANGANIKALLABES ALBOPERCA SP. NOV.
Diagnosis: Tanganikallabes alboperca sp. nov. is distinguished from all congeners by its relatively shorter pelvic fins (6.0–7.7% SL versus 7.1–9.3% SL in other Tanganikallabes species ), which do not reach past the origin of the anal fin when adpressed (versus reaching past the anal fin origin in all other Tanganikallabes species ). It is also distinct from other Tanganikallabes species in the presence of a well-defined, depigmented border on the operculum, which extends from the upper margin of the operculum all the way to the union of the gill membranes at the isthmus (border absent in T. mortiauxi and T. stewarti sp. nov.).
Tanganikallabes alboperca sp. nov. is further distinguished 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 ), 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 overlying io-ii in T. mortiauxi ; Fig. 3 View Figure 3 ), its incomplete lateral line (versus complete in T. mortiauxi ), shorter pectoral fin spine (3.6–5.3% SL versus 5.6–8.8% SL in T. mortiauxi ), generally lower number of dorsal fin rays [65–74 (modally 70) versus 72–81 (modally 80) in T. mortiauxi ], smaller eye (0.8– 1.6% SL versus 1.8–3.0% SL in T. mortiauxi ), and lack of a free lower orbital margin. Tanganikallabes alboperca sp. nov. is further separated from T. stewarti sp. nov. by having a relatively deeper body (body depth at anus 11.7–14.6% SL versus 8.7–10.9% SL in T. stewarti sp. nov.), longer lateral line (see below description of T. stewarti sp. nov.), greater preanal length (45.2– 49.0% SL versus 42.4–44.8% SL in T. stewarti sp. nov.), and by generally having a lower number of anal fin rays [55–63 (modally 59) versus 63–69 (modally 65) in T. stewarti sp. nov.].
Description: Morphometric data in Table 4, frequency distributions of selected meristic data in Table 3. Maximum TL 180 mm, SL 160 mm. Body elongate, moderately compressed posterior to origin of dorsal fin. Predorsal slightly convex, with small indentation formed by curvature and insertion of cheek muscles on skull. 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.
fin i,5; tip of adpressed fin does not reach beyond origin of anal fin. Anal fin elongate, with 55–63 branched rays; posterior margin not joined with caudal fin. Caudal fin i,7,8,i; rounded.
Coloration in alcohol: Dorsum and flanks uniformly light to dark brown, ventral surfaces noticeably lighter ( Fig. 9 View Figure 9 ). All barbels pigmented as body on their proximal half, distal half lacking pigmentation. All fins with brownish bases and narrow, depigmented border; border wider in younger specimens. Operculum with wide, depigmented margin, extending onto underside of head.
Distribution: Lake Tanganyika. Tanganikallabes alboperca sp. nov. is apparently distributed lakewide, although existing collections come only from the extreme southern and northern areas of the lake ( Fig. 10 View Figure 10 ).
Habitat: Habitat details for this species are absent for the collections examined. It is likely to inhabit rocky bottoms, over a range of depths, as is the case for T. mortiauxi .
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.
Nasal barbel short; not extending to any aspect of opercular flap. Maxillary barbel occasionally extends beyond margin of opercular flap, but is usually shorter. Lateral mandibular barbel extending to, or slightly beyond, lower opercular margin. Medial mandibular barbel short, slightly over half the lateral mandibular barbel length. All barbels smooth, with very narrow basal membrane.
Dorsal fin elongate, lacking spine, with 65–74 soft rays; origin located well behind vertical through posterior tip of adpressed pectoral fin; posterior margin not joined with caudal fin. Pectoral fin I,7,8; strong spine, well-developed venom glands present; spine approximately half the length of pectoral fin; posterior margin of spine with between zero and five very small, retrorse serrations. Adipose fin absent. Pelvic Diet: The stomachs of three specimens (from UMMZ 199937 and UMMZ 199861) contained, collectively, fish eggs (species indeterminate), the remains of a single platythelphusid crab, and insect larvae.
Etymology: The specific epithet, alboperca , is a combination of the latin adjective alba, meaning white, and the noun operculum, meaning lid or cover, a reference to the distinctive depigmented posterior margin seen in the operculum of this species. Gender: feminine.
Material examined: Holotype: UMMZ 199936 View Materials (153 mm SL), E. side of Nyika Bay , N. side of Nkumbula Island, Zambia Lake Tanganyika, 31.X.1970 . Paratypes: UMMZ 199937 View Materials (7 alc, 1 c&s; 102– 155 mm SL), collection data as for holotype ; UMMZ 199861 View Materials (27 alc, 2 c&s; 47–152 mm SL), N. end of Nkumbula Island , 2 km N. of Mpulungu, Zambia, Lake Tanganyika, 1.XI.1970 ; UMMZ 196021 View Materials (2 alc; 122–146 mm SL), Zambia, Lake Tanganyika (no additional data) ; SAIAB 76160 View Materials (3 alc; 66– 145 mm SL), Mbita Island (north-west end), 8°45.18′S, 31°05.07′E, Zambia, Lake Tanganyika, 29.II.2004 GoogleMaps ; SAIAB 86974 View Materials (1 alc; 115 mm SL), Sumbu , 8.5167°S, 30.4833°E, Zambia. Lake Tanganyika, 00 GoogleMaps . V.1983; SAIAB 86968 View Materials (1 alc; 105 mm SL), Chimba , 08°25.27′S, 30°27.44′E, Zambia, Lake Tanganyika, 07.III.2004 GoogleMaps ; SAIAB 80225 View Materials (1 alc; 99 mm SL), Chituta Bay , cliffs, bottom of bay on west side, 8°43.82′S, 31°9.41′E, Zambia, Lake Tanganyika, 09.III.2004 GoogleMaps ; MRAC 125751 View Materials (1 alc; 104 mm SL), Luhanga, Lake Tanganyika , 13.II.1959 ; MRAC 78025.0013 View Materials , 78025.0014 View Materials (2 alc; 83–104 mm SL), Cape Kabeyeye, Zambia, Lake Tanganyika , I.1978 ; MRAC 78025 View Materials . 0013, 78025.0014 (1 alc; 93 mm SL), Cape Kabeyeye, Zambia, Lake Tanganyika , I.1978 ; MRAC 76004.0566 View Materials (1 alc; 126 mm SL), Cape Nunda, southern Lake Tanganyika , Zambia, 6.I.1976 ; MRAC 130952– 130970 View Materials (4 alc; 141–161 mm SL), Kalungwe, Lake Tanganyika , 11.VII.1961 ; MRAC 187088 View Materials (1 alc; 104 mm SL), Nkumbula Island , Lake Tanganyika, Zambia, 14.VII.1965 ; MRAC 81062.0001 View Materials (1 alc; 146 mm SL), Kabimba, 50 km N. Albertville, Lake Tanganyika , Democratic Republic of Congo, 7.IV.1981 .
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