Dactylosoma piperis Úngari, 2020

Úngari, Letícia Pereira, Netherlands, Edward Charles, Santos, André Luiz Quagliatto, Alcantara, Edna Paulino de, Emmerich, Enzo, Silva, Reinaldo José da & O’Dwyer, Lucia Helena, 2020, A new species, Dactylosoma piperis n. sp. (Apicomplexa, Dactylosomatidae), from the pepper frog Leptodactylus labyrinthicus (Anura, Leptodactylidae) from Mato Grosso State, Brazil., Parasite (Paris, France) 27 (73), pp. 1-13 : 3-5

Dactylosoma piperis Úngari , Netherlands, Silva & O’Dwyer n. sp.

urn:lsid:zoobank.org:act:92749FA8-8673-4556-B03FF925A15B8A07

Type-host: Leptodactylus labyrinthicus ( Anura : Leptodactylidae ).

Type-locality: Municipality of Araguaiana , Mato Grosso State, Brazil (coordinates 14 ° 35 0 47 00 S 51 ° 43 0 9.59 00 W) .

Site of infection: Peripheral blood erythrocytes.

Parasitaemia: 0.2%.

Etymology: The host species L. labyrinthicus is commonly referred to in Brazil as the pepper frog. Therefore, the species epithet is derived from the Latin word piperis meaning pepper (noun in apposition).

Material deposited: Hapantotype, two blood smears from L. labyrinthicus deposited in the collection of the National Institute of Amazonian Research ( INPA), Manaus, Brazil [ INPA 19a, INPA 19b].

Gene sequence: 18S rRNA gene sequence deposited in GenBank under accession number MW 264134.

Note: The authors of the new taxon are different from the authors of this paper; Article 50.1 and Recommendation 50A of the International Code of Zoological Nomenclature [ 41].

Description ( Fig. 1 ; Table 1 ):

The developmental stages of the unidentified species of Dactylosoma observed were trophozoites, early stage meronts, meronts and merozoites from the primary merogony. For secondary merogony, it was possible to identify early stage meronts, meronts and merozoites. In addition, the early stage meronts and the mature meronts varied in morphology including the typical hand-like (dactylate shape), the quadrangular, the fan-like and circular shapes. Typically, primary merogony of species of Dactylosoma produces up to 16 merozoites and secondary merogony up to eight merozoites. However, in the present study, during primary merogony, meronts were observed producing up to ten chromatin divisions of the nuclei and during secondary merogony, meronts were observed producing up to eight chromatin divisions ( Fig. 1 ).

Primary merogony

Trophozoite ( Fig. 1A ): Elongated, tapering towards one end and larger and rounded at opposite end, measuring 7.4 µm ± 1.3 µm long, 3.75 µm ± 1.5 µm wide, and with area of 19.31 µm 2 ± 0.4 µm 2; cytoplasmic vacuoles observed mainly in tapering end; nuclei placed at the rounded end, although chromatin division is not clearly defined; cytoplasm staining whitish-purple (n = 5).

Young primary meronts ( Fig. 1B ): Ovoid to round shape with dispersed vacuoles, measuring 5.20 µm ± 0.15 µm in length, 5.53 µm ± 0.7 µm in width, with area of 20.41 µm 2 ± 0.4 µm 2; multinucleate, with between four to six nuclei located peripherally and staining purple; causes displacement of host nuclei and cell (n = 2),

Primary meronts ( Figs. 1C–1D ): Large rounded meronts, measuring 8.59 µm ± 0.2 µm in length, 6.73 µm ± 0.5 µm in width, with area of 31.40 µm 2 ± 0.4 µm 2; causing slight distortion and displacement of host cell nucleus; multinucleate with between 6 and 10 nuclei located peripherally; purplish or pinkish staining chromatin (n = 3).

Primary meronts with merozoites ( Figs. 1E–1F ): Large fan-shaped meronts with distinct triangular form, measuring 8.38 µm ± 0.1 µm in length, 6.71 µm ± 0.25 µm in width, with area of 31.24 µm 2 ± 0.5 µm 2 (n = 3); multinucleate with ovoid dense chromatin positioned on one side of the parasite, usually displacing erythrocyte nuclei, chromatin staining dark purple or pinkish; merozoites measurements 7.45 µm ± 0.25 µm in length and 2.90 µm ± 0.25 µm in width (n = 30).

Secondary merogony

Young secondary meront ( Figs. 1G–1H ): Elongated with one end tapered and the other rounded. Rounded end containing two to three nuclei, with dense and circular chromatin staining in deep magenta peripherally distributed, with or without cytoplasmic vacuole, 6.1 µm ± 1.2 µm length, 4.15 µm ± 0.9 µm width and 28.02 µm 2 ± 0.2 µm 2 in area (n = 3).

Secondary meronts ( Figs. 1I–1J ): Dactylate (hand-like) appearance, ovoid to round shape, 6.9 µm ± 0.4 µm length, 5.6 µm ± 0.2 µm width and 25.53 µm 2 in area (n = 2); multinucleate with between five and eight nuclei located peripherally with dense chromatin staining in deep magenta.

Secondary meronts with merozoites ( Figs. 1K–1L ): Morphology varying from fan-like shape to quadrangular shape. Multinucleate with between six and eight nuclei with chromatin division located peripherally, with or without vacuoles; in some cases, slight displacement of host cell nucleus evident. Quadrangular shape meront ( Fig. 1K ): Multinucleate with six rounded nuclei, three dense nuclei positioned on each side of the meront, forming a square-shape, measuring 7.54 µm ± 0.2 µm long, 5.4 µm ± 0.9 µm wide, and with area of 25.88 µm 2 (n = 2). Merozoites measured 6.2 µm ± 0.2 µm long and 1.5 µm ± 0.9 µm wide (n = 12). Fan-like shape meront ( Fig. 1L ): Multinucleate with 8 nuclei, ovoid dense chromatin positioned on one side of meront, forming fan-like shape; usually displacing host cell nucleus, measuring 6.95 µm long, 4.89 µm wide, and with area of 23.68 µm 2 (n = 1). Merozoites measured 5.88 µm ± 0.2 µm long and 1.3 µm ± 0.9 µm wide (n = 8).

Differential diagnosis

Dactylosoma piperis n. sp. is characterised by its elongated and unique trophozoites, with one side rounded and the other tapered; the morphological variation of early stage meronts to mature meronts ranging between dactylate, fan-like, quadrangular and circular shapes, and the number of merozoites produced in primary merogony (up to 10) and secondary merogony (up to eight).

This species can be distinguished from all currently recognised species of Dactylosoma from anuran hosts, namely D. kermiti , D. ranarum , D. sylvatica , and D. taiwanensis based on several developmental characteristics, such as the number of nuclear chromatin divisions present in primary and secondary merogony, unique trophozoite morphology and developmental stage morphometrics.

In comparison, D. piperis n. sp. differs from D. ranarum (the first described species in the Dactylosomatidae ), in the number of chromatin divisions of up to six nuclei during secondary merogony and trophozoite morphology being slender and smaller with both ends rounded. Nevertheless, certain characteristics observed, such as meronts with merozoites arranged in fan-like fashion or quadrangular mass, and the two types of schizogony (primary and secondary), are typical of dactylosomatid parasites. The first type producing larger meronts with nuclei located peripherally and vacuoles present during merozoite formation, and the second type producing smaller meronts, with chromatin division of nuclei more condensed and staining dark-purple with fewer merozoites produced.

For D. kermiti , primary merogony is characterised by up to 14 chromatin divisions and second merogony by up to six chromatin divisions, as compared to D. piperis n. sp., with up to 10 and up to 8 chromatin divisions observed in primary and secondary merogony, respectively. In addition, the trophozoites of D. kermiti are smaller and slender, and elongated to oval in shape with vacuoles present, measuring 6.7 µm ± 2.2 µm long and 3.5 µm ± 1.2 µm wide, which differs from the trophozoite size and shape of D. piperis n. sp. Also, the morphometric values of primary meronts and merozoites, and secondary meronts and merozoites from this study were larger as compared to D. kermiti .

In comparison, the developmental stages between D. sylvatica and D. piperis n. sp. differ in morphology and size, with trophozoites of D. sylvatica measuring lager (7.0–8.5 µm × 6.3–7.6 µm), with an amoeboid shape, circular nuclei and alveolar cytoplasm without inclusions. Furthermore, meronts of D. sylvatica produce only up to eight merozoites, in the first and the second merogony, as compared to up to ten in the first merogony and eight in the second merogony of D. piperis n. sp.

With regard to D. taiwanensis and D. piperis n. sp., both species present similar trophozoite morphology, with trophozoites of D. taiwanensis measuring 3.9 µm wide and 7.3 µm long; distinguished morphology can be observed, with elongate or ovoid vacuolated form with equal rounded ends, compared to elongated with one end rounded and the other tapered from D. piperis n. sp. From secondary merogony, mature fan-like, quadrilateral-shape and hand-like meronts were observed with between four and eight nuclei, differing from the mature meronts of D. piperis n. sp. with between six and eight nuclei.

Figures

Figure 1. Dactylosoma piperis n. sp. in blood smears of Leptodactylus labyrinthicus. Primary merogony (A–F): A) Trophozoite; B) Young primary meront; C–D) Primary large rounded meronts; E–F) Fan-like shaped primary meronts with merozoites. Secondary merogony (G–L): G–H) Young secondary meronts; I–J) Secondary meronts with dactylate appearance; K–L) Secondary meronts with merozoites. Scale bar: 10 µm.