ABSTRACT Two new Phenacogrammus are described from the Ndzaa River, a small left-bank tributary of the Mfimi-Lukenie River in the central Congo basin. They share with P. deheyni, a congener endemic to the Cuvette Centrale to the north, a prominent anterior expansion of the first pleural rib; a feature interpreted here as a synapomorphy diagnostic for this species assemblage. The two new species are readily differentiated from P. deheyni based on differences in pigmentation patterning, a lower number of scales in longitudinal series (26–28 vs. 29–33) and a longer head length (m. 24.9% SL vs. 21.7 and 23.2% SL). Phenacogrammus flexus, new species, is distinguished from all congeners in the possession of 6 (vs. 7) supraneural bones, and a characteristic zigzag pattern of black pigmentation along and below the midline extending from the posterior border of the opercle to the base of the caudal peduncle. While no unambiguous morphological autapomorphies have been located to diagnose P. concolor, new species, it is nonetheless readily distinguished from all congeners, except P. deheyni and P. flexus, in the possession of a prominent anterior expansion of the first pleural rib. It differs from both P. deheyni and P. flexus in the absence of a dominant pigmentation patterning over the flanks and caudal peduncle. Additionally, it differs from P. flexus in a shallower body depth (m. 24.9% vs. 27.0% SL) and in the possession of 7 (vs. 6) supraneurals. The three species exhibit extensive divergence in mt-COI sequence (P. flexus vs. P. concolor 10.2%–11%; P. flexus vs deheyni 12.9%–13.5%; P. concolor vs. deheyni 11.3%–12.9%). Furthermore, analysis of shape variation utilizing geometric morphometrics indicates that each species differs significantly in body shape.

中文翻译：

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来自刚果民主共和国中非 Ndzaa 河 (Mfimi-Lukenie 盆地) 的两种新的 Phenacogrammus (Characoidei; Alestidae)

摘要从刚果盆地中部 Mfimi-Lukenie 河的左岸小支流 Ndzaa 河中描述了两种新的 Phenacogrammus。它们与 P. deheyni 相同，P. deheyni 是 Cuvette Centrale 北部特有的同源物，第一胸膜肋明显向前扩张；一个特征在这里被解释为这个物种组合的突触诊断。这两个新物种很容易与 P. deheyni 区分开来，基于色素沉着图案的差异、纵向系列中较少数量的鳞片（26-28 对 29-33）和较长的头长（m. 24.9% SL 对 21.7和 23.2% 止损）。Phenacogrammus flexus 是一个新物种，与拥有 6 个（vs. 7）神经上骨的所有同类物不同，以及沿中线和下方的特征性锯齿形黑色色素沉着图案，从中线从鳃盖后缘延伸到尾柄基部。虽然没有发现明确的形态学自体形态来诊断 P. concolor，新物种，但它仍然很容易与除 P. deheyni 和 P. flexus 之外的所有同系物区分开来，具有第一胸膜肋的显着前部扩张。它与 P. deheyni 和 P. flexus 的不同之处在于侧面和尾柄上没有明显的色素沉着图案。此外，它与 P. flexus 的区别在于较浅的身体深度（m. 24.9% 对 27.0% SL）和拥有 7 个（对 6 个）超神经元。这三个物种在 mt-COI 序列中表现出广泛的差异（P. flexus 与 P. concolor 10.2%–11%；P. flexus 与 deheyni 12.9%–13。5%；P. concolor 与 deheyni 11.3%–12.9%）。此外，利用几何形态学分析形状变化表明，每个物种的体型差异很大。