Kudoa ajurutellus, Neto & Cardim & Da Silva & Hamoy & Matos & Abrunhosa, 2020

Neto, José Pompeu Araújo, Cardim, Joyce, Da Silva, Diehgo T., Hamoy, Igor, Matos, Edilson & Abrunhosa, Fernando, 2020, Kudoa ajurutellus n. sp. (Multivalvulida: Kudoidae), a parasite of the skeletal musculature of the Bressou sea catfish, Aspistor quadriscutis, in northeastern of the State of Pará, Zootaxa 4718 (3), pp. 371-380 : 374-377

Kudoa ajurutellus n. sp.

was observed in live fish and no evidence of myoliquefaction was observed. The staining of the histological sections revealed no inflammatory response to Pseudocysts found in the musculature of the hosts ( Fig. 3A ). Some discreet disorganization was also observed in the myofibrils of the musculature at the sites where the pseudocysts were observed ( Fig. 3B ).

Molecular Analysis. A partial sequence of 908 base pairs of the 18S rDNA gene was obtained from the spores of Kudoa ajurutellus n. sp. recovered from the skeletal musculature of A. quadriscutis . This sequence was deposited in GenBank under access number MK089553 .

The phylogenetic analysis generated a tree with a single large clade, denominated A, containing the Kudoa species, with an outgroup consisting of Gastromyxum rafii Freeman & Kristmundsson 2015 and Gastromyxum bulani Freeman & Kristmundsson 2015 . Clade A was divided into two subclades, A1 and A2. Kudoa ajurutellus n. sp. was allocated to clade A1, which was formed by Kudoa species that parasitise marine fish hosts. The clustering of subclade A1 was related primarily to the tissue tropism of the host ( Fig. 4 ), with Kudoa ajurutellus n. sp. parasitising the musculature of the marine fish, A. quadriscutis . The other species of clade A1 parasitise the muscle, brain, intestine, esophagus, ovary, heart and systemic infection of their hosts. Kudoa ajurutellus n. sp. is phylogenetically closest to K. lethrini ( Burger, Cribb & Adlard 2007) and K. neurophila (Grossel et al. 2005) , which both parasitise the brain, respectively, of Gymnocranius audleyi and Latris lineata . Kudoa ajurutellus n. sp. was the basal taxon of clade A1. Subclade A2 is formed by Kudoa spp. parasites of the muscle and heart.

The optimal evolutionary models for the maximum likelihood (ML) and Bayesian analyses were determined by W-IQ-TREE ( Trifinopoulos et al. 2016) which identified the best evolutionary model as the general time reversible model (GTR+F+I). Nucleotide frequencies were estimated (A = 0.2865, C = 0.1826, G = 0.2547, T = 0.2762) and six rates of nucleotide substitution were calculated, with AC = 1.1603, AG = 3.6633, AT = 2.3450, CG = 0.6466, CT = 6.5433, GT = 1.00000. The proportion of invariable sites was 0.4451 and the alpha value of the gamma distribution parameter was 0.4865. This smallest P distance between Kudoa ajurutellus n. sp. and other Kudoa species was 4.43% ( Table 2 ).

Kudoa ajurutellus n. sp. has the following taxonomic classification

Phylum Cnidaria Hatschek, 1888

Subphylum Myxozoa Grasse, 1970

Class Myxosporea Butschli, 1881

Order Multivalvulida Shulman, 1959

Family Kudoidae Meglitsch, 1960

Genus Kudoa Meglitsch, 1947

Species Kudoa ajurutellus n. sp

Host: Aspistor quadriscutis ( Siluriformes : Ariidae ).

Locality: Ajuruteua beach in the municipality of Bragança, in the northeastern extreme of the state of Pará, Brazil.

Infection site: Pseudocysts in skeletal muscle.

Prevalence: 77.6% (44% for males and 33.6% for females).

Etymology: The specific name ajurutellus refers to the name of a fruit (Ajuru), which is very common at the type locality, Ajuruteua, in the municipality of Bragança in the state of Pará, Brazil. The name of the locality is also derived from the fruit.

Deposit of the type specimen: Histological sections of Kudoa ajurutellus n. sp. stained with ZN (ziehl-neelsen)

were deposited in the International Protozoan Type Specimen Collection at the Brazilian National Institute of Amazonian Research (INPA) in Manaus, Amazonas, Brazil (catalog number: INPA 037 ). The sequence of the Small Subunit of the ribosomal RNA (18S rDNA) was deposited in GenBank ( Access number: MK089553 ). ZooBank number for species: urna: lsid: zoobank.org: act: A1A 893F 0-0B46-48D0-9882-671B7A 82580F.

Figures

FIGURE 3. Histological sections: A. Muscle (F) infected with pseudocysts of Kudoa ajurutellus n. sp. in myofibrils (arrow head), stained with HE under DIC. Scale bar: 20 µm. B. Greatest increase pseudocysts of Kudoa ajurutellus n. sp. (*) in fiber musculare, stained with HE. Scale bar: 20 µm.

FIGURE 4. Phylogenetic tree generated by the Bayesian Inference (BI) analysis of the aligned partial 18S rDNA gene sequences of Kudoa ajurutellus n. sp. and related Kudoa spp.. The GenBank accession numbers are shown adjacent to the species names. The numbers at the nodes are posterior probability values calculated for BI. The new species is shown in bold type.