Batrachops, sensu Heckel, 1840

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 : 1010-1014

Batrachops . Node 149, which in the ML tree represents the subgenus Batrachops , excluding C. jegui , show 11 synapomorphies, most of them congruent with characteristics used in previous diagnoses of the C. reticulata group and useful to partially diagnose the subgenus Batrachops herein (char. 40: 0=>1 A; char. 41: 0=>2 A; char. 52: 2=>3; char. 73: 0=>1; char. 78: 0=>1; char. 131: 0=>2; char. 176: 0=>2; char. 206: 0=>1).

Diagnosis: Species in the subgenus Batrachops , except C. (B.) jegui , are distinguished from all remaining pike cichlids by the reticulate colour pattern on the flanks emerging from the dark pigmentation on the base of the scales. However, the conspicuosness of the resulting horizontal stripes forming this pattern can vary across species and through ontogeny. Species in the subgenus Batrachops , except C. (B.) jegui , are also distinguished from all remaining pike cichlids by expressing the dark blotch on the caudal fin displaced posteriorly and dorsally in relation to the base of the caudal fin and the posterior branch of the lateral line, and from all remaining species of the subtripe Crenicichlina , except those in the subgenus Lacustria , by the orange or reddish marking of the lateral abdomen in sexually mature females. All species of the subgenus Batrachops , except C. (B.) jegui and C. (B.) cyclostoma , are distinguished from all other pike cichlids, except some species of Lugubria and C. (La.) vittata , by having almost the entire caudal fin densely covered by scales (vs. caudal fin only partially covered by scales and scales arranged in single or two series along the inter-radial membranes).

All species in the subgenus Batrachops are additionally distinguished from the subgenus Crenicichla by the dark vertical bars expressed as a series of blotches along the midlateral area in adults, by the presence (vs. absence) of a caudal blotch, and by the cycloid (vs. ctenoid) scales on the cheek. Batrachops is additionally distinguished from the subgenus Lacustria by the absence of a dark suborbital marking. Crenicichla (B.) jegui has a well-defined, uniformly pigmented suborbital stripe running obliquely from the ventral margin of the orbit to the corner of the preopercle, a unique condition of the species among the subgenus, presumably not homologous with the suborbital marking formed by dark dots of the subgenus Lacustria .

All species of the subgenus Batrachops are additionally distinguished from Saxatilia by the absence of a humeral blotch, from Lugubria by 55–75 (vs. 88–123) scales in the E1 series, and from Wallaciia by their larger body size (max. SL 96–216 mm vs. 52–85 mm in Wallaciia ) and by the absence of serrations on the posterior border of the suplacleithrum (except W. heckeli , with smooth supracleithrum). All species of the subgenus Batrachops are also distinguished from Teleocichla and Hemeraia by having autogenous post-lachrymal infraorbitals (vs. infraorbitals 4 and 5 coossified, forming a median pore); they are further distinguished from Teleocichla by the rounded pelvic fin with the second ray longest (vs. pelvic pointed with third ray longest), and by prognathous or isognathous jaws (vs. hypognathous jaws). Further distinguished from Hemeraia by having most scales on flank ctenoid (combination of patterns 1 and 3 on the dorsal portion and pattern B2 on the ventral portion of the body) vs. having most scales on flank cycloid (combination of patterns 3 and B3; see characters 25 and 26 and Supporting Information, Appendix S2, Fig. S2).

Remarks: Most species of the subgenus Batrachops correspond to the previously proposed C. reticulata group, traditionally characterized by a cylindrical body, depressed head, short snout, and large gape, all of which have been correlated with the occupation of benthic habitats (e.g. Kullander 1986; Ploeg 1991). However, in rapids of the Río Tocantins, the sympatric species C. (B.) jegui and C. (B.) cyclostoma represent strong deviations from the typical Batrachops morphology. Crenicichla (B.) jegui is a reophilic, sedentary (bottom sitter) species with very depressed body and head, eyes dorsally displaced on the head, and distinctly prognathous jaws. The reticulate colour pattern widespread among Batrachops species is replaced by a coarse pattern of light blotches and vermiculations on the entire dorsal portion of the body, suggesting cryptic coloration in fast-flowing, turbulent waters. Contrastingly, C. (B.) cyclostoma lives among dark rocks in moderate- to fast-flowing waters of the Río Tocantins and has laterally compressed body and head with a darker overall coloration. The two species also differ in the feeding apparatus, suggesting distinctive diets and foraging strategies. All species of the subgenus Batrachops have oral jaw teeth in the outer row firmly fixed, while teeth in the inner rows are slightly movable, a character that helps to distinguish Batrachops from the subgenus Crenicichla , the genera Saxatilia , Lugubria , Wallaciia , and Hemeraia , and from most species of the subgenus Lacustria . However, while outer row teeth in most species of Batrachops are unicuspid and moderately robust, C. (B.) jegui has caniniform teeth (long and thin), and the teeth of C. (B.) cyclostoma are unusually large and thick, suggesting pronounced differences in diet among the three lineages. Similarly, the lower pharyngeal jaw (LPJ) differs, with the common condition in the subgenus being a robust and wide LPJ bearing papilliform teeth on its medioposterior portion, whereas in C. (B.) jegui the LPJ is longer and thinner, bearing only cuspidated teeth, and in C. (B.) cyclostoma the LPJ is stout and strongly sutured, bearing strong molariform teeth. All this suggests that C. (B.) jegui may be a specialized, probably ambush, predator and C. (B.) cyclostoma is probably durophagous, foraging on rocky substrates similarly to Teleocichla preta ( Varella et al. 2016) . As a result of these ecomorphologically unique attributes, finding universally diagnostic characters shared between C. (B.) jegui , C. (B.) cyclostoma , and the remaining species of the subgenus Batrachops remains challenging.

Distribution: Amazon basin (main channel and tributaries), Río Orinoco, and Essequibo river basins. Crenicichla (B.) semifasciata is the only species found in the Río Paraguai and in the lower and middle portions of the Río Paraná. Recent reports from the upper Río Paraná basin probably result from anthropogenic introductions ( Roa-Fuentes et al. 2015).

Node 127— Crenicichla (Lacustria) , new subgenus of Crenicichla u r n: l s i d: z o o b a n k.o r g:a c t: D 8B 7 4 0 B 7- E F 5 6-

437E-8DCA-530741D4D775

Type species: Cycla lacustris Castelnau, 1855 .

The subgenus Lacustria is recovered in all analyses performed herein with high support in the ML and BI trees (BS 100% and PP 91.1%), but low support in the parsimony analysis of EW/DiscreteMatrix (ABS 3/RBS 20%; Table 6). It is also recovered in the recent phylogenies based on molecular data exclusively ( Piálek et al. 2012; Burress et al. 2017, 2018). Six morphological synapomorphies (four unambiguous and two ambiguous) and 37 molecular unambiguous transformations are optimized for the Node 127 in the ML tree ( Table 12)—all of them coincident with the optimization on the consensus tree based on parsimony analysis of the EW/DiscreteMatrixTE.

Diagnosis: Species of the subgenus Lacustria are distinguished from all species of pike cichlids by the presence of a dark suborbital pattern formed by a variable number of conspicuous dark spots (punctulations), more or less scattered over the cheek. Species of Lugubria , Saxatilia , and Hemeraia also have a suborbital marking, as well as C. (B.) jegui , but this is interpreted as another pattern, not formed by spots but uniformly pigmented (see characters 57–60). Species of the subgenus Lacustria are further distinguished from most species of Lugubria by the presence of 41–75 scales in the E1 row (vs. 88–123), with the exception of C. (La.) vittata (79–93 scales), and by the absence of a dark blotch behind the pectoral fin (vs. blotch appearing in adults of most Lugubria species). From Saxatilia , all species of Lacustria are distinguished by the absence of a humeral blotch and by sexually dimorphic females with an orange or reddish marking laterally on the abdomen instead of a broad reddish or purplish pigmentation on the ventral portion of the abdomen of Saxatilia .

Lacustria is distinguished from the subgenus Batrachops , except C. (B.) cyclostoma , by the laterally compressed body (vs. nearly cylindrical or depressed) and from Batrachops , except C. (B.) jegui , by the absence of a reticulate colour pattern on the flank resulting from the dark pigmentation on the base of each flank scale. Lacustria differs from the subgenus Crenicichla by the presence of cycloid (vs. ctenoid) scales on the cheek, dorsal head, and area anterior to the dorsal fin, and on the chest; by the presence of a caudal blotch and by sexually dimorphic females showing orange or reddish marking on the lateral abdomen and, occasionally, one or more dark blotches on dorsal fin (vs. absence of these sexually dimorphic features related to coloration). Species of Lacustria are additionally distinguished from Wallaciia by their size (max. SL 95–294 mm vs. 52–85 mm) and by the smooth posterior margin of the supracleithrum (vs. posterior margin with serrations in all Wallaciia , except W. heckeli ). The subgenus is additionally distinguished from Teleocichla and Hemeraia by having all the post-lachrymal infraorbitals autogenous (vs. infraorbitals 4 and 5 co-ossified forming a median pore).

Distribution: Atlantic coastal rivers in Brazil (from the Río Buranhem to the Laguna dos Patos system) and in the Río Paraná, Río Uruguay, and Río Paraguay basins (Río de La Plata superbasin). A recently discovered, undescribed species expands the distribution of the subgenus to the Río São Francisco basin in north-eastern Brazil (H. Varella, pers. obs.).

Remarks: Our results agree with all previous studies based on molecular data, which place Crenicichla vittata among the species of the subgenus Lacustria , former C. lacustris group ( Fig.3). This is the only species of the subgenus widely distributed in the three major rivers of the La Plata superbasin and falls in different positions of the subgenus depending on the analysis performed. Before those recent studies, C. (La.) vittata was considered a member of the C. lugubris group (e.g. Kullander 1991, 1997; Ploeg 1991; Fig. 3I), mainly by being a medium to large species with numerous small scales on the flanks.

Less inclusive groups in the subgenus Lacustria : Node 153 corresponds with what has been called the C. missioneira group or complex since Lucena and Kullander 1992 or Uruguay River species flock (URSF, Burress et al. 2017, 2018; Fig. 3 D−F). This group is recovered in all analyses performed herein and is well-supported in the ML and BI topologies (BS 100% and PP 100%) but has low support in the parsimony analysis of EW/DiscreteMatrixTE (ABS 2/RBS 20%; Table 6). Besides the species included as terminal taxa in the analyses performed herein, the C. missioneira Character transformation Apomorphic condition Observations

Char. 59: 0=>1 Presence of dark suborbital punctulations. A unique transformation of the Node 127.

Char. 85: 0=>1 Sexually dimorphic females showing dark one or Convergent transformations optimized more dark blotches on the dorsal fin. as synapomorphy of a less inclusive group of Wallaciia ( Node 186) and as autapomorphy of C. (B.) cyclostoma , and a reversal occurs in C. (La.) vittatta .

Char. 124: 0=>1 Posterior border of the alveolar process of the Convergent transformations optimized premaxilla curved, bulbous. as autapomorphies of several species of Teleocichla and Hemeraia chicha .

Char. 202: 1=>0 Microbranchiospines regularly distributed on A reversal to the plesiomorphic state in-

the external (lateral) face of the second to side the subtribe Crenicichlina .

fourth branchial arches.

Ambiguous

Char. 66: 0=>1 A Post-temporal dark marking present in adults. This character is very homoplastic inside the subtribe Crenicichlina . Optimized also as synapomorphies of the Node 132 (Clade Hemeraia-Lugubria-Saxatilia) and of Teleocichla , and with two reversals inside the subgenus Crenicichla (Lacustria) .

Char. 177: 1=>2 A Posterior foramen of the nasal unique or This is a very homoplastic character and divided, diplaced anterior and with the pos- the state 2 represents a secondary modi-

terior portion of the canal ossified, resulting in fication of the synapomorphic condition the openings placed at the middle of the nasal of pike cichlids (state 1).

canal.

complex also includes Acharches niederleinii , considered a nomen dubium of the Río Uruguay (Río Chapecó) that could correspond to C. (La.) missioneira , C. (La.) minuano , or C. (La.) hadrostigma ( Varella 2011; Steinhauser 2019). All species are endemic to the middle and upper Río Uruguay basin.

The C. missioneira complex can be characterized by 10 morphological synapomorphies (seven of them unambiguous) and 91 unambiguous molecular transformations. Among the morphological synapomorphies, four are useful to diagnose the group among the species of the subgenus Lacustria and were used in the previous characterization of the group by Lucena and Kullander (1992): char. 12: 2=>1: lachrymal as long as deep (approximately square) vs. lachrymal longer than deep; char. 60: 1=>2 D: dark suborbital marking composed of one or few spots restricted to the posterior portion of the cheek; char. 71: 0=>1: presence of a dark blotch on the pectoral axila; and char. 150: 2=>0 A: posterior margin of the preopercle smooth, with no serrations. Additionally, most species of the C. (La.) missioneira complex show sexually dimorphic males with the dark blotch of the caudal fin fragmented, accompanying the pattern of irregular small blotches scattered on the caudal peduncle.

The C. missioneira complex is the sister-group of all remaining species of Lacustria , encompassing several species from the Atlantic coastal drainages of Brazil, the Río Paraná, Río Paraguay, and the Río Uruguay basins. The C. scottii complex ( sensu Lucena and Kullander 1992 ) is recovered in all analyses performed herein ( Node 179). It includes the three remaining valid species of the subgenus distributed in the Río Uruguay basin: C. (La.) scottii , C. (La.) gaucho , and C. (La.) prenda . The clade is well-supported in the ML and BI analyses (BS 100% and PP 100%), and in the parsimony analysis of EW/DiscreteMatrixTE (ABS 3/RBS 100%; Table 6). Twelve synapomorphies (nine of them unambiguous) and 39 unambiguous molecular transformations characterize the group. Species of this group have been traditionally differentiated from other species in the subgenus by having their body less compressed laterally, a wider interorbital area, short snout, and a blunt, wide mouth. Some of these characteristics were optimized as synapomorphies for the group viz. char. 13: 1=>0: ascending process and dentigerous arm of the premaxilla with similar lengths; char. 15: 1=>0: frontal bones less compressed laterally (interorbital distance 26.3–50.9% of the neurocranium length); and char. 175: 1=>0: nasal canal short and curved; and char. 176: 0=>2: laminar ossification of the nasal canal well-developed both medially and laterally. Other synapomorphies of the C. missioneira group are related to their teeth, arranged in fewer series but more firmly fixed onto the jaws (char. 129: 0=>1 A; char. 130: 0=>1; and char. 131: 0=>2). These characters have been used to distinguishing this group from many species of Lacustria (e.g. Lucena and Kullander 1992).

The C. mandelburgeri complex ( Piálek et al. 2012), or Paraná River species flock ( Burress et al. 2018), is recovered as monophyletic ( Node 163) with high support in the ML tree (BS 98%), but moderate support in the BI consensus tree (PP 58.3%), and low support in the parsimony analysis based on EW/DiscreteMatrixTE (ABS 3/RBS 17; Table 6). Although this group is characterized by one synapomorphy only, it is exclusive for the group: char. 86: 0=>1: dark blotches on the dorsal fin of sexually dimorphic females modified into a unique horizontal dark band. The synapomorphic condition and the composition of the group agree with Piálek et al. (2012), with the exception of the inclusion of C. (La.) jaguarensis . A group formed with all endemic species of the Río Paraná basin is only found in the parsimony analyses under equal weighting (EW/ DiscreteMatrixTE and EW/ContinuousMatrixTE), but not in the ML and BI analyses, as well as in the other parsimony analyses performed herein. This is due to to the discordant position of Crenicichla (La.) sp. Paraná within the subgenus. Because of its distribution in the region of the Itaipu reservoir (transition between upper and middle Río Paraná), further reassessment of the relationsips of the species is necessary to better understand the biogeography of the subgenus Lacustria .

Hypertrophied lips in the subgenus Lacustria : Hypertrophied lips, such as those observed in C. (La.) tendybaguassu and C. (La.) tuca , have evolved exclusively within the subgenus Lacustria of Crenicichla . Similar phenotypes are found in phylogenetically distant lineages in African lakes (e.g. Colombo et al. 2013; Baumgarten et al. 2015) and Central America (e.g. Elmer et al. 2010; Manousaki et al. 2013) but are not found in other pike cichlids or Geophagini taxa. The labial turgescence in the geophagine Gymnogeophagus labiatus is not considered homologous as it does not result in the formation of median lobes ( Lucena and Kullander 1992).

According to our results, the occurrence of hypertrophied lips is not restricted to C. tendybaguassu and C. tuca , but also observed in two other morphologically defined, putative new taxa belonging to the subgenus Lacustria in the Río Iguaçu basin. Three pairs of big-lipped/typical taxa of pike cichlids in the Río Iguaçu basin, matching in relation to overall shape and coloration, were included in the combined phylogenetic analysis. Crenicichla iguassuensis BL and C. tesay BL are big-lipped forms corresponding to C. iguassuensis and C. tesay , respectively. The third pair is C. tapii (typical) and C. tuca (big lips). Crenicichla iguassuensis BL and C. tesay BL were represented in the combined datasets only with morphological data and the remaining were represented with both molecular and morphological data.

Only Crenicichla tuca and C. tapii are recovered as sister-taxa in our main hypothesis (ML tree), in the BI tree, and in some of the parsimony analyses. The other big-lipped forms do not group with their typical-lipped correspondents. Piálek et al. (2012) also suggested the existence of several lineages of big-lipped pike cichlids in the Río Iguaçu basin. More recently, and with a more complete sampling, Rícan et al. (2021a) found several different big-lipped forms within both C. missioneira and C. mandelburgeri complexes, but this study was inconclusive regarding the species delimitation within these clades.

According to the optimization of morphological characters on the ML tree ( Fig. 4), hypertrophy with the formation of ventral and dorsal lobes ( Fig. 4: char. 97) is convergent in Crenicichla tendybaguassu , C. tuca , C. tesay BL , and C. iguassuensis BL (char. 97). The development of the lobes can vary largely intraspecifically and during ontogeny (Supporting Information, Appendix S2, Fig. S22), and it is accompanied by the development of a mental process ( Fig. 4: char. 97) on the dentary, but this occurs convergently in C. jupiaensis and C. (Batrachops) cyclostoma , which have strong oral jaws and symphyseal teeth. Osteological modifications codified herein, correlated with narrowing and downturning of the mouth (characters 13, 91, 128, 142, and 159) and increment of biting force (characters 127, 131, 132, and 133), are not exclusive of big-lipped taxa, but occur in several species that deviate from the typical pelagic-predatory morphology of pike cichlids. Narrowing of the mouth is more pronounced in big-lipped forms of the Río Iguaçu basin when compared with their typical-lipped correspondents. The difference is more evidente in the pair C. iguassuensis (typical Crenicichla pelagic predator, with wide mouth gape and prognathous jaws) and C. iguassuensis BL (crevice feeder, with narrow mouth gape and isognathous jaws).

Considering our comparisons between big-lipped and typical-lipped correspondents, features on the LPJ (directly correlated to food processing, e.g. Burress et al. 2017), are more conservative than those on the oral jaws (correlated to foraging). LPJ of big-lipped and typical-lipped correspondents are similar in shape and robustness (character 205) and type of teeth on the medioposterior portion (character 206), but the LPJ of big-lipped taxa shows denser dentition [as already pointed out by Lucena and Kullander (1992) for C. tendybaguassu in the context of the C. missioneira complex]. Even in C. iguassuensis vs. C. iguassuensis BL pair, with pronounced differences on morphology of oral jaws, the LPJ of the big-lipped form has denser dentition but is very similar in shape and types of teeth (only unicuspid and bicuspid teeth, no papilliform or molariform teeth, which suggests preference for durophagy). The only clearly specialized molluscivorous species in the Río Iguaçu basin is what we identify as C. yaha ( sensu Varella 2011 ; but for incongruences on species delimitations between authors, see also: Piálek et al. 2015), with much enlarged medioposterior teeth on the LPJ, and this is the only species that does not have a big-lipped correspondent.