Convergence is Only Skin Deep: Craniofacial Evolution in Electric Fishes from South America and Africa (Apteronotidae and Mormyridae)

Apteronotidae and Mormyridae are species-rich clades of weakly electric fishes from Neotropical and Afrotropical freshwaters, respectively, known for their high morphological disparity and often regarded as a classic example of convergent evolution. Here, we use CT-imaging and 3D geometric morphometrics to quantify disparity in craniofacial morphologies, and to test the hypothesis of convergent skull-shape evolution in a phylogenetic context. For this study, we examined 391 specimens representing 78 species of Apteronotidae and Mormyridae including 30 of 37 (81%) of all valid genera with the goal to sample most of the craniofacial disparity known in these clades. We found no overlap between Apteronotidae and Mormyridae in the skull-shape morphospace using PCA and a common landmark scheme, and therefore no instances of complete phenotypic convergence. Instead, we found multiple potential instances of incomplete convergence, and at least one parallel shift among electric fish clades. The greatest components of shape variance in both families are the same as observed for most vertebrate clades: heterocephaly (i.e., opposite changes in relative sizes of the snout and braincase regions of the skull), and heterorhynchy (i.e., dorsoventral changes in relative snout flexion and mouth position). Mormyrid species examined here exhibit less cran- iofacial disparity than do apteronotids, potentially due to constraints associated with a larger brain size, ecological constraints related to food-type availability. Patterns of craniofacial evolution in these two clades depict a complex story of phenotypic divergence and convergence in which certain superficial similarities of external morphology obscure deeper osteological and presumably developmental differences of skull form and function. Among apteronotid and mormyrid electric fishes, craniofa- cial convergence is only skin deep

Blood-Feeding Behavior of Culex tarsalis at Medicine Lake National Wildlife Refuge, Montana

It is known that the ornithophillic mosquito, Culex tarsalis is the primary vector of West Nile Virus (WNV) in Montana. An analysis of this mosquito’s blood feeding behavior allows researchers to identify preferred hosts and to determine the rate at which this species parasitizes humans and other tangential hosts. Additionally, an understanding of blood feeding behavior allows an assessment of WNV risk based on the regional availability of preferred hosts and the hosts’ competency in viral amplification. In this study, blood engorged Cx. tarsalis were captured at Medicine Lake National Wildlife Refuge over three one-week periods spaced through early, middle, and late summer. Vertebrate DNA was isolated from mosquito blood meals and a fragment of the COI gene was PCR amplified to determine host species. Additionally, avian surveys were conducted at mosquito collection sites so that each bird’s relative abundance could be compared to its incidence in blood meals. The two most common host species were the Mourning Dove comprising 59% of blood meals and the American Robin comprising 33%. These species were ranked 4th and 14th, respectively in observed abundance out of the 47 species counted in this study. These results suggest that Cx. tarsalis at Medicine Lake NWR exhibits a feeding preference for these two species

A new species of air-breathing catfish (Clariidae: Clarias) from Salonga National Park, Democratic Republic of the Congo (American Museum novitates, no. 3990)

20 pages : illustrations (chiefly color), color map ; 26 cmA new species of air-breathing catfish, Clarias monsembulai, is described from Congo River tributaries within and bordering the Salonga National Park (Democratic Republic of the Congo). The new taxon is recognized by its exceptionally long, white barbels, which lend a superficial resemblance to Clarias buthupogon, from which it differs in characters of the cleithrum and pigmentation patterning. We suggest placement of this species into the subgenus Clarioides but note the current dearth of morphological data to unite members of this group. We additionally discuss the validity of the subspecies Clarias angolensis macronema

Fig.7 in A New Species of Deep-channel Electric Knifefish Compsaraia (Apteronotidae, Gymnotiformes) from the Amazon River

Fig.7. Collection localities of Compsaraia compsa (triangles)and Compsaraia samueli (squares). Some single points indicate more than one lot or collection from proximate localities

Fig. 1. Compsaraia iara, MZUSP 121514, 203 in A New Species of Deep-channel Electric Knifefish Compsaraia (Apteronotidae, Gymnotiformes) from the Amazon River

Fig. 1. Compsaraia iara, MZUSP 121514, 203 mm TL, holotype, Brazil, Pará, Rio Amazonas. Scale bar equals 1 cm

Fig.2 in A New Species of Deep-channel Electric Knifefish Compsaraia (Apteronotidae, Gymnotiformes) from the Amazon River

Fig.2. (A) Compsaraiasamueli,male,MUSM 54638,199mmTL,Peru,Loreto,RioNanay.(B)Compsaraiasamueli,female,MUSM54620,137mm TL,Peru, Loreto,Rio Amazonas.(C) Compsaraia compsa, ANSP 160194, paratype,262 mm TL,Venezuela,Apure, Rio Meta.Scale bar equals 1 cm

Mosaic Evolution of Craniofacial Morphologies in Ghost Electric Fishes (Gymnotiformes: Apteronotidae)

Ghost electric knifefishes (Gymnotiformes: Apteronotidae) are a dominant component of the species diversity and biomass of large lowland rivers in Greater Amazonia, including 77 species that exhibit diverse craniofacial morphologies associated with trophic and secondary sexual traits. Here we use open-source computed microtomography (lCT) scans to generate 3D reconstructions for a majority of apteronotid species and almost all valid genera, and geometric morphometric and phylogenetic analyses to explore patterns of skull evolution. As with most vertebrates, principal component 1 (PC1) summarizes variance from brachycephalic to dolichocephalic morphologies, previously described as heterocephaly, and PC2 summarizes variance from recurved (upturned) to decurved (downturned) snout morphologies, described here as heterorhynchy. Phylomorphospace and traitogram analyses found instances of both convergent and divergent evolution along both of the first two PC axes, as well as a preponderance of clades characterized by morphological stasis or phylogenetic conservatism. Certain phenotypic combinations predominate among species and clades, including elongated-downturned snouts and foreshortenedupturned snouts, while other phenotypic combinations are not observed, including elongated-upturned snouts and foreshortened-downturned snouts. These results highlight the power of 3D geometric morphometrics in the study of craniofacial evolution and indicate developmental or functional constraints in the evolution of craniofacial phenotypes in an ecologically dominant clade of riverine Amazonian fishes

Melanosternarchus Amaru, A New Genus And Species Of Electric Ghost Knifefish (Gymnotiformes: Apteronotidae) From The Amazon Basin

We describe Melanosternarchus amaru as a new genus and species of Apteronotidae from the deep channels of blackwater and clearwater tributaries of the Amazon River in Brazil and Peru. The new species superficially resembles members of the widespread “Apteronotus” bonapartii species group, from which it can be readily distinguished by expanded bones of the infraorbital laterosensory canal. It can further be distinguished from all other apteronotids by a unique combination of characters: reduced premaxillary dentition, a large gape, and an absence of scales from the entire dorsum. A molecular phylogenetic analysis using three mitochondrial loci and one nuclear locus (~3000 bp) places this genus as sister to Compsaraia, and these two genera together as a clade sister to Pariosternarchus; all nodes with strong statistical support. The clade formed by these three genera includes five species, four of which are restricted to the Amazon basin. The apparent habitat preference of the new species for low-conductivity blackwater and clearwater rivers has not been reported in other apteronotid species

Data supporting phylogenetic reconstructions of the Neotropical clade Gymnotiformes

Data is presented in support of model-based total evidence (MBTE) phylogenetic reconstructions of the Neotropical clade of Gymnotiformes “Model-based total evidence phylogeny of Neotropical electric knifefishes (Teleostei, Gymnotiformes)” (Tagliacollo et al., 2016) [1]). The MBTE phylogenies were inferred using a comprehensive dataset comprised of six genes (5277 bp) and 223 morphological characters for an ingroup taxon sample of 120 of 218 valid species and 33 of the 34 extant genera. The data in this article include primer sequences for gene amplification and sequencing, voucher information and GenBank accession numbers, descriptions of morphological characters, morphological synapomorphies for the recognized clades of Gymnotiformes, a supermatrix comprised of concatenated molecular and morphological data, and computer scripts to replicate MBTE inferences. We also included here Maximum-likelihood and Bayesian topologies, which support two main gymnotiform clades: Gymnotidae and Sternopygoidei, the latter comprised of Rhamphichthyoidea (Rhamphichthyidae+Hypopomidae) and Sinusoidea (Sternopygidae+Apteronotidae)

Aldaetal_SystBio_SupplMat

Supplementary Tables S1-S4, and Supplementary Figures S1-S16