Hemeraia, Varella & Kullander & Menezes & Oliveira & López-Fernández, 2023

Varella, Henrique R, Kullander, Sven O, Menezes, Naércio A, Oliveira, Claudio & López-Fernández, Hernán, 2023, Revision of the generic classification of pike cichlids using an integrative phylogenetic approach (Cichlidae: tribe Geophagini: subtribe Crenicichlina), Zoological Journal of the Linnean Society 198 (4), pp. 982-1034 : 1020-1022

Node 148— Hemeraia , new genus urn:lsid:zoobank.org:act:6F581429-473C-480E-

9D6D-6B4898DF1A7C

Type species: Crenicichla hemera Kullander, 1991

Hemeraia , comprising only H. hemera and H. chicha , is recovered in all analyses performed herein, although in different positions within the subtribe Crenicichlina (see Remarks): as sister-group of the clade Saxatilia (ML and BI trees); in a trichotomy with Saxatilia and Lugubria (Parsimony/EW/DiscreteMatrixTE); as sister-group of the the clade Saxatilia + Lugubria (Parsimony/XIW/DiscreteMatrixTE); and as sister-group of all remaining pike cichlids (parsimony analysis of ContinuousMatrixTE under EW and XIW schemes). As this is the first phylogenetic study that included both H. hemera and H. chicha , there are no previously published phylogenetic hypotheses for comparisons.

Nevertheless, monophyly of the genus is well supported in the ML and BI trees (BS 98% and PP 100%), and has moderate support in the parsimony tree based on EW/DiscreteMatrixTE (ABS 5/ RBS 63%; Table 6). The two known species in the genus were represented only by morphological data, but nonetheless the clade was diagnosable by six unambiguous and one ambiguous synapomorphies ( Table 15). Synapomorphic conditions of characters 25, 26, and 105 help to diagnose the group among pike cichlids and coincide with diagnostic characters in previous taxonomic papers that included the two species ( Varella et al. 2012, 2018).

Diagnosis: Hemeraia is distinguished from other pike cichlids by the combination of: reduced distribution of ctenoid scales (vs. cycloid) on flanks (pattern 3 and B3; see characters 25, 26 and Supporting Information, Appendix S2, Fig. S2); a smooth preopercle (vs. serrated); infraorbitals 4 and 5 co-ossified, forming a median pore (vs. autogenous); and presence of a suborbital marking. Hemeraia is further distinguished from Lugubria by having fewer scales in the E1 series (58–75 vs. 89–123). Hemera is further distinguished from Saxatilia by the absence of a humeral blotch that appears in early ontogenetic stages (only adults of H. hemera shows a dark blotch just posterior to the pectoral fin that resembles a humeral blotch but appears only late in ontogeny). Hemeraia is further distinguished from all species of Teleocichla , which also have infraorbitals 4 and 5 co-ossified and (most of them) a smooth preopercle, by having typical pike-cichlid morphology without the various characters related to rheophyly found in Teleocichla , including the pelvic pointed with third ray longest, almost reaching the genital papilla, mouth downturned, reduced cheek squation, and some degree of molarization of LPJ teeth.

Distribution: Hemeraia hemera is distributed in the Río Aripuanã basin and H. chicha in the Río Juruena, Río Tapajós basin.

Remarks: The position of species of Hemeraia species within the subtribe Crenicichlina is controversial in both previous taxonomic studies and in our present work. Ploeg (1991) allocated Crenicichla guentheri (junior synonym of C. hemera ) among the species of the C. saxatilis group, which herein corresponds to Saxatilia . Varella et al. (2012), in the description of Crenicichla chicha and based mainly on external morphology, considered Hemeraia hemera and H. chicha as sister-taxa by sharing features such as reduced ctenoid squamation on flanks, smooth preopercle, and infraorbitals 4 and 5 co-ossified. However, their placement in any of the major groups of pike cichlids remained unclear because these species share some characters (mostly related to meristics) with the C. saxatilis (herein Saxatilia ) group and others with the C. lugubris (herein Lugubria ) group (related to ontogenetic change of coloration).

The discordance of the position of Hemeraia between our different analyses may be partially due to the lack of molecular data, together with the use of the first 16 characters as continuous data. The clade gathering Hemeraia , Saxatilia , and Lugubria , i.e. node 131 in ML tree ( Fig. 2 left) and node 129 in the parsimony tree based on EW/DiscreteMatrixTE ( Fig. 2 right), is supported by five and six unambiguous synapomorphies, respectively. Among these, characters 4 (number of dorsal-fin rays) and 5 (number of anal-fin rays) are multistate quantitative characters treated as continuous in the ContinuousMatrixTE. As a side-effect of treating additive characters as continuous, these characters are downweighted in the analysis and the resulting shifts are different from the discretizations of the states performed a priori. This side-effect would have been of little impact if molecular data of these species were available to be included in the analyses.