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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 : 1006-1010

Node 123—genus Crenicichla Heckel 1840

Crenicichla Heckel, 1840: 416 (type species Crenicichla macrophthalma Heckel, 1840 , designated subsequently by Eigenmann and Bray 1894: 620).

As mentioned above, the genus Crenicichla as redefined herein presents high node support in the ML and BI trees, and moderate support in the main parsimony analysis (EW/DiscreteMatrixTE) ( Table 6). The clade is supported by few unambiguous synapomorphies that correspond to homoplastic characters ( Table 9) but is supported by 32 molecular transformations. The same morphological synapomorphies are found from the optimization on the EW/ DiscreteMatrixTE pasimony tree.

As redefined herein, Crenicichla comprises 43 valid species divided into three subgenera: Crenicichla (one species), Batrachops (nine species), and Lacustria (33 species); see Table 1. The genus Crenicichla shows great morphological and ecological diversity, which challenges the formulation of a good diagnosis for the group. Thus, we make use of a combination of several characteristics to distinguish the species of Crenicichla from the other pike cichlids, organized by morphological groups.

Diagnosis: All species of Crenicichla , except C. macrophthalma , can be distinguished from other pike cichlids by sexually dimorphic characters that include orange or reddish marking on the lateral abdomen of mature females. Apart from C. macrophthalma , which is known to lack such dimorphism, other species for which there is no information on the coloration of mature females probably show this feature (see the distribution of states of character 89). In most species of Crenicichla , female marking on the lateral abdomen is accompanied by one or more blotches on the dorsal fin; in some taxa, these blotches are eventually modified into a horizontal dark bar. While this characteristic is shared with some species of Wallaciia , it is absent in the remaining species of pike cichlids.

All species of Crenicichla are distinguished from most species of Saxatilia and Lugubria by the absence of a broad reddish or purplish pigmentation on the ventral part of the abdomen of gravid females. All species of Crenicichla are additionally distinguished from Saxatilia by the absence of a humeral blotch and of sexual dimorphism consisting of scattered light spots on mature males— Crenicichla (Batrachops) jegui has light dots scattered on the flanks and head but their presence is not sexually dimorphic. All species of Crenicichla are distinguished from Lugubria by having fewer than 79 scales in the E1 row, except Crenicichla (Lacustria) vittata with 79–93 scales (vs. 79–123 scales in the species of Lugubria ).

All species of Crenicichla have all post-lachrymal infraorbitals autogenous vs. infraorbitals 4 and 5 fused, forming a median pore in Teleocichla and Hemeraia . Exceptions are the unique specimen of C. (La.) igara examined herein, which shows infraorbitals 4 and 5 partially fused, and C. (La.) jupiaensis , with only four instead of five infraorbitals but without signal of co-ossification (see: Varella et al. 2018). Species of Crenicichla are additionally distinguished from Hemeraia by having most of the flank scales ctenoid [i.e. a combination of patterns 1 and B 2 in all Crenicichla except C. (C.) macrophthalma , which shows a combination of patterns 0 and B1] vs. most of the flank scales cycloid (i.e. combination of pattern 3 and B3). Species of Crenicichla are additionally distinguished from Teleocichla by having rounded pelvic fin with the second ray longest (vs. pointed pelvic fin with the third ray longest), by having a stick-like pharyngobranchial 1 (vs. globular pharyngobranchial 1), by showing the configuration of the urohyal similar to other pike cichlids, i.e. lateral wings wider than the depth of the medial crest (vs. lateral wings wide but medial crest rudimentary or absent), and by having the symmetrical medial processes of the basipterygia diverging anteriorly (vs. running very close, not diverging anteriorly).

All species of Crenicichla are also distinguished from all species of Wallaciia , except W.heckeli , by the absence of serrations on the posterior margin of the supracleithrum. Additionally, Crenicichla comprises medium-sized species (max. SL 95–294 mm) with relatively small eyes (orbital diameter 4.6–10.9% of SL, with minimum between 4.6–7.5%) and clearly showing a negative allometry of eye size (eyes decreasing proportionally in size with ontogeny), with the exception of C. macrophthalma , a medium-sized species (max. SL 200 mm) with large eyes in small to large specimens (orbital diameter 9.4–10.6% of SL), with less marked negative allometry in eye size. Thus, Crenicichla can be distinguished from Wallaciia , which comprises only small-sized species (max. SL 52–85 mm) with large eyes (orbital diameter 7.8–12.6% of SL, with minimum between 7.8–8.6%).

Node 122— Crenicichla (Crenicichla) Heckel 1840 — type subgenus of Crenicichla .

Type species: Crenicichla macrophthalma Heckel, 1840 .

Nominal species: Crenicichla macrophthalma and C. santaremensis (synonym of C. macrophthalma ).

The subgenus is recovered in all analyses performed herein with high support in ML and BI trees (BS 100% and PP 100%) and moderate support in the parsimony analysis of EW/DiscreteMatrixTE (ABS 5/ RBS 63%; Table 6). The subgenus is diagnosed by 50 molecular transformations and 19 morphological synapomorphies ( Table 10). The same morphological synapomorphies are found from the optimization on the parsimonious tree from EW/DiscreteMatrixTE, except for characters 98 and 168 (only in the ML optimization).

Apart from some characters related to external morphology, such as squamation (characters 23, 24, 25, 26, 27, and 40) and colour patterns (51, 71, and 80), autapomorphies come from highly homoplastic characters inside the subtribe Crenicichlina and are of little value in formulating a diagnosis for the species.

Character 98 (state 1: eyes visible in ventral view) was optimized as one of the apomorphic conditions of the subgenus, with convergences also optimized as synapomorphies of Saxatilia and Wallaciia . It was difficult to decisively infer whether the visibility of the eyes (in ventral view) resulted from two variables instead of one: size of the eye and its relative position in the head. In Saxatilia , the eyes are situated more laterally in the head (wide interorbital space). Crenicichla (C.) macrophthalma and Wallaciia are recognized to have larger eyes, which occupy a large portion of the upper lateral portion of the head because of their size and because the interorbital space is narrow. Further evaluation of this character based on ontogenetic information or even a reinterpretation may be important for subsequent analyses.

Diagnosis: Crenicichla (Crenicichla) macrophthalma is a medium-sized species of pike cichlid (max. SL 200 mm) that can be distinguished from all other pike cichlids by the following combination of characters: large eyes (orbital diameter 9.4–10.6% of SL); body almost entirely covered by ctenoid instead of cycloid scales (scales ctenoid on cheek, flank squamation following patterns 0 and B1, and scales ctenoid covering the caudal fin almost entirely); and the absence of dark markings below the eye (suborbital marking) and on caudal blotch. Among pike cichlids, only C. (La.) vittata shows a similar squamation pattern but is readily distinguished from C. (C.) macrophthalma by having more scales in the E1 series (79–93 vs. 65–68) and by having a suborbital marking, a conspicuous dark midlateral band on flank, and a caudal blotch.

A d d i t i o n a l c o m p a r i s o n s b e t w e e n g r o u p s: T h e monotypic subgenus Crenicichla is distinguished from almost all species of the subgenera Batrachops and Lacustria by the absence of sexual dimorphism expressed by mature females with orange or reddish pigmentation on the lateral abodomen and by dark blotches on the dorsal fin of mature females. The latter character also distinguishes the subgenus Crenicichla from most species of Wallaciia . Crenicichla (Crenicichla) macrophthalma is distinguished from most species of Saxatilia and Lugubria by the absence of a reddish or purplish broad pigmentation on the ventral abdomen (belly) of mature females. The subgenus Crenicichla also differs from Saxatilia by the absence (vs. presence) of a humeral blotch, from Lugubria by having fewer scales in the E1 series (65– 68 vs. 88–123), from Wallaciia (except W. heckeli ) by the absence of serrations on the posterior margin of supracleithrum, and from Teleocichla and Hemeraia by having all post-lachrymal infraorbitals autogenous vs. infraorbitals 4 and 5 co-ossified, forming a median pore. The subgenus also differs from Hemeraia by having regularly serrated instead of smooth preopercle and from Teleocichla by having a pelvic fin with rounded margin and second ray longest instead of pointed with third ray longest.

Distribution: Crenicichla macrophthalma is known from tributaries (Río Negro, Río Trombetas, Río Tapajós and Río Xingu) and the main channel of the Amazonas River.

Node 133— Crenicichla (Batrachops) Heckel 1840 , subgenus of Crenicichla

Batrachops Heckel 1840: 432 (type species Batrachops reticulatus Heckel 1840 , designated subsequently by Eigenmann and Bray 1894: 620).

Boggiania Perugia 1897: 148 (type species Boggiania ocellata Perugia 1897 = Batrachops reticulata ), as junior synonym.

The node representing the subgenus Batrachops has relatively good support in the ML tree (BS 88%), moderate in the BI tree (PP 64%), and low support in the parsimony analysis of EW/DiscreteMatrixTE (ABS 3/RBS 20%; Table 6). The clade is supported by eight morphological synapomorphies (no molecular synapomorphies), being five unambiguous and three ambiguous ( Table 11)—all of them congruent with the optimization performed on the tree obtained from the parsimony analysis of EW/DiscreteMatrixTE.

None of them corresponds to characteristics used in previous papers to diagnose the C. reticulata group, except for character 150 state 1, which distinguishes Crenicichla and Batrachops sensu Heckel (1840) . The lack of unambiguous apomorphies in Batrachops is probably due to the inclusion of Crenicichla (Batrachops) jegui , with a morphology that diverges from the remaining species of the subgenus in several aspects (see Remarks). Indeed, C. (B.) jegui was previously placed in the C. lugubris group by Ploeg (1991) and has been placed among the species of Character transformation Apomorphic condition Observations

Char. 48: 0=>1 Lateral portion of the pelvic fin with skin Convergences occur in other groups of pike thickening. cichlids. Condition apparently related to rheophilic behaviour.

Char. 155: 0=>1 Medial process (ascendent) of the proximal extrascapula about twice longer than the distal process.

Char. 162: 0=>2 Lateral crest of epioccipitals on the eppiocitals only.

Char. 163: 0=>1 Caudal opening of the posterior myodome ab- Convergent transformations optimized as sent. autapomorphies of several species.

Char. 211: 1=>0 Posterior margin of the glossohyal convex. Convergent transformation as synapomorphy of Teleocichla .

Ambiguous

Char. 14: 1=>2 A Horizontal portion of the preopercle longer Optimized as a synapomorphy, but with a than the vertical portion. reversal on the node 150, which comprises four of the six terminal taxa of the group.

Char. 129: 0=>1 A Decreasing to two or three rows of teeth in Convergences as synapomorphies of the C.

the symphyseal region of the premaxilla. (La.) scottii complex (node 179) and as autapomorphy of C. (La.) jupiaensis .

Char. 150: 2=>1 A Posterior margin of the preopercle with few weak serrations irregularly distributed.