Description of two new Labeo (Labeoninae; Cyprinidae) endemic to the Lulua River in the Democratic Republic of Congo (Kasai ecoregion); a hotspot of fish diversity in the Congo basin Liyandja, Tobit L. D. Stiassny, Melanie L. J. American Museum Novitates 2023 2023-05-18 2023 3999 1 22 [438,547,599,625] Actinopterygii Cyprinidae Labeo Animalia Cypriniformes 13 14 Chordata species undetermined    HOLOTYPE: AMNH 269110 ( AMCC 249240, CT), 121.2 mm SL, main channel of the Lulua Riverover rocks at Sandoa(Sanduwa), 0.05 kmdownstream of Sandoa Bridge,  Lualaba Province, D.R.C., 09°41′37.2″S, 022°51′30″E, J.J. Mbimbiand T. Liyandja,  September 2014.   PARATYPES: AMNH 269103 ( AMCC 249230, CT), 97.3 mm SL, main channel of the Lulua Riverin rocky and rapids habitat about 0.35 kmdownstream of crossing point on road to Kapanga,  Lualaba Province, D.R.C., 08º16′04.3″S, 022º35′50.2″E, J.J. Mbimbiand T. Liyandja,  September 2014; AMNH 277861 ( AMCC 249238–9, 2, 2 CT), 52.88–70.46 mm SL, collected with AMNH 269103; ZSM 48370 (2, 1 CT), 50.23–74.47 mm SL, Lukushi River(tributary of Lulua) at Mukandarapids,  Lualaba Province, D.R.C., 10°30′25.4″S, 23°23′ 33.8″E, E. Vrevenet al.,  August 2012.   ADDITIONAL NONTYPE MATERIAL: AMNH 247858, 1, 116.4 mm SL, main channel of the Lulua Riverover rocks at Ntumba Shambuyi Rapidslocated 2.23 kmdownstream of Dipumu Rapids, Kasai  Central Province, D.R.C., J.J. Mbimbi,  July 2008. DIFFERENTIAL DIAGNOSIS: While no unambiguous morphological autapomorphies have been located to diagnose  Labeo manasseeaethe species is distinguished from all central African  L. forskaliigroup congeners except  L. dhonti,  L. lukulae,  L. luluae,  L. mbimbii,  L. parvus,  L. quadribabrbis, and L. simpsoniin the possession of 28 vertebrae (vs. 30 or more).  Labeo manasseeaeis distinguished from  L. lukulae,  L. luluae, and  L. quadribarbisby a larger interpectoral width (94.7%–107.9% vs. 66.7%–92.8% BD), from  L. parvus,  L. quadribarbis, and  L. simpsoniby a shorter vent–anal-fin distance (5.0%–6.9% vs. 11.4%–7.1% SL), and from  L. dhontiand  L. lukulaein the possession of 30–31 (vs. 35–36) pored lateral-line scales. It is distinguished from  L. mbimbiiin the possession of 3 fully developed supraneural bones (vs. 4), 4 predorsal vertebrae (vs. 5), a pointed snout with a shallow ethmoid furrow and weakly developed fleshy appendage versus a truncate snout with a deep ethmoid furrow and well-developed fleshy appendage, and a gracile, narrow-necked, shallow-keeled (vs, robust, thick-necked, and deep-keeled) urohyal bone.  DESCRIPTION: Based on the holotypeand five paratypes. General appearance as in figure 7, proportional measurements and meristic counts in table 2. Small-bodied species, maximum observed size 121.2 mm SL( holotype), elongate, cylindriform, somewhat dorsoventrally compressed ( BD 16.1%–19.2% SL). Genital opening situated well in advance of anal-fin origin, vent–  TABLE 2.  Labeo manasseeae, n. sp., morphometric measurements and meristic data for the holotype and  five paratypes.  Holotype Holotype+ Paratypes Max Min Mean±SD Morphometric measurements Standard length (mm) 121.2 121.2 50.2 Head length (mm) 31.5 31.5 14.3 22.3±6.8 Body depth (mm) 22.2 22.2 8.9 15.0±5.4 Caudal peduncle length (mm) 15.9 15.9 6.2 10.4±4.9  % SL Body depth (BD) 18.3 19.2 16.1 17.5±1.2 Caudal peduncle depth (CPD) 13.7 14.7 12.1 13.2±1.0 Head length (HL) 26.0 28.9 26,0 26.7±1.0 Predorsal length (PDL) 44.8 48 44.8 46.5±1.1 Preanal length (PAL) 81.6 81.7 79.8 81.2±0.7 Prepelvic length (PVL) 56.2 59.6 56.2 57.2±1.2 Prepectoral length (PPL) 25.7 29.5 25.7 27.3±1.3 Dorsal-fin base (DFL) 20.0 22.7 19.6 20.8±1.2 Dorsal-fin length (DRL) 24.2 27.9 23.7 26.2±1.8 Pectoral-fin length (PL) 20.5 21.8 18.9 20.7±1.0 Pelvic-fin length (VL) 17.9 19.1 16.9 18.3±0.8 Anal-fin base (AL) 7.5 8.5 7.3 7.7±0.4 Anal-fin length (ARL) 18.8 19.2 16.9 18.5±0.8 Vent–anal-fin length (VAL) 6.4 6.9 5.0 6.2±0.6 Caudal peduncle length (CPL) 13.1 13.4 11.7 12.5±0.6  % HL Snout length (SnL) 52.1 51.5 45.5 48.5±2.4 Interorbital width (IOW) 36.2 39.1 33.3 35.6±2.5 Internarial width (INW) 27.5 30.1 23.7 26.4±2.7 Bony orbital diameter (ED) 24.3 28.2 19.8 24.2±2.9 Postorbital length (POL) 27.7 33.9 28.0 30.8±1.9  %BD Interpectoral width (IPW) 101.3 107.9 94.7 101.3±4.3  %CPL Caudal peduncle depth (CPD) 104.8 121.4 98.5 106.6±8.8  Meristic countsMax Min Mode Simple dorsal-fin rays 4 4 4 4 Branched dorsal-fin rays 10 10 10 10  TABLE 2 continued    Holotype Holotype + Paratypes  Max Min Mean±SDMode  Scales in lateral line 31+3 31+3 30+3 31+3  Scale rows between lateral line and dorsal-fin origin 4 4 4 4  Scale rows between lateral line and pelvic-fin origin 3 3 3 3  Circumpeduncular scales 12 13 12 12  Predorsal scales 9 10 8 9  Principal caudal-fin rays 19 19 19 19  Upper procurrent caudal-fin rays 8 8 8 8  Lower procurrent caudal-fin rays 7 7 6 6  Simple pelvic-fin rays 1 1 1 1  branched pelvic-fin rays 8 8 8 8  Simple anal-fin rays 3 3 3 3  Branched anal-fin rays 5 5 5 5  Total vertebrae 28 28 28 28  Abdominal vertebra 15 16 15 15  Caudal vertebra 13 13 12 13  Pleural ribs 12 13 12 12 anal-fin distance 5.0%–6.9% SL. Head moderately large, with slightly convex interorbital space. Snout narrow and pointed, ethmoid furrow shallow, weakly developed fleshy appendage bearing 8 or more small tubercles. Eyes large, dorsolaterally positioned, not visible in ventral view. Mouth relatively small, inferior, lips plicate, anterior barbels small (absent in large specimens), posterior barbels small, deeply embedded in lip fold, externally visible in small specimens. Dorsal fin, iv10 rays, margin slightly concave, inserted just anterior to midbody (predorsal length 44.8%–48.0% SL), anal fin iii5 rays. Caudal fin strongly emarginate, 8 upper, 6–7 lower procurrent rays, 19 principal rays. Pectoral fins broad, inserted lateroventrally, interpectoral width 94.7%–107.9% BD. Pelvic fins, i8, slightly shorter than pectorals. Scales cycloid, 30–31 inlateral line to hypural joint; 4 between lateral line and dorsal-fin origin; 3 between lateral line and pelvic-fin origin; 12 circumpeduncular. Total vertebral count (exclusive of 4 Weberian centra and the terminal preural centrum), 28, comprised of 15–16 (mode 15) abdominal and 12–13 (mode 13) caudal centra. The Weberian apparatus of  L. manasseeaeis relatively massive (fig. 8A), with anterior Weberian supraneural 3 relatively gracile, 1.3× longer than tall, and in direct contact with the supraoccipital. No supraneural between the neural spine of the fourth Weberian centrum and the neural spine of the first predorsal centrum. Three fully developed supraneural bones anterior to the neural spines of predorsal centra 2–4 (a vestigial fourth supraneural bone is present in the holotype, but absent in all other specimens). Four predorsal vertebrae. Urohyal (fig. 8B) is gracile, thin necked, with a shallow keel. Infraorbital series (fig. 8C) consists of an elongated first infraorbital (lachrymal) and four additional elements, none of which are ventrally expanded or in contact with the preopercle.  FIGURE 7.  Labeo manasseeae, n. sp.Holotype (AMNH 269110, AMCC 249240): A.immediately postmortem; B.in preservation, lateral view; C.ventral view; and D.dorsal view. Scale bar = 1 cm COLORATION: Immediately postmortem (fig. 7A) coloration varies from brown to dark brown or black above, pale brown to cream below, a dark lateral band is barely visible at any size. Preserved specimens (fig. 7B–D) are dark brown above and brown below, and dark lateral band is visible in most specimens.  DISTRIBUTION: A Lulua River endemic,  Labeo manasseeaeis known mainly from the middle basin, with single records from the lower and upper basins (fig. 1). However, due to inaccessibility the upper Lulua has been poorly sampled ( Mbimbi et al., 2021) and it is likely that additional collecting efforts will expand the range of this species.  BIOLOGY AND ECOLOGY:  Labeo manasseeaehas been collected in rocky, rapids habitats in the main channel of the middle Lulua, with one occurrence in a tributary of the upper basin. As for  L. mbimbii,  L. manasseeaeappears to be adapted to rocky, rapids habitats of both the main channel and tributaries. The water in the main channel sites where  L. manasseeaewas collected is slightly acidic (pH 5.5–6.5), has low conductivity (2–5 µS/cm 2), and low concentration of dissolved solids (TDS 4–10 ppm).  ETYMOLOGY: Dedicated to Manassée W.E. Liyandja, the daughter of Tobit Liyandja. Manassée was born a few months prior to the expedition that led to the discovery of this new species and is an ongoing source of motivation for T.L. 2014-09 CT, SL Lualaba Province, D. R. C. & J. J. Mbimbi & T. Liyandja Lualaba Province -9.693666 Lulua River 15 22.858334 Sandoa Bridge 13 14 AMCC 249240 1 holotype 2014-09 CT, SL Lualaba Province, D. R. C. & J. J. Mbimbi & T. Liyandja Lualaba Province -8.26786 Lulua River 1 22.597279 Kapanga 13 14 AMCC 249230 1 paratype 2012-08 CT, SL Lualaba Province, D. R. C. & E. Vreven Lualaba Province -10.507055 Lukushi River 1 23.392721 Mukanda 13 14 AMCC 249238-9, 2 1 paratype 2008-07 SL Central Province, D. R. C. Lulua River Dipumu Rapids Ntumba Shambuyi Rapids 13 14 1 Kasai-Oriental SL 13 14 BD 16.1 1 holotype