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Revista chilena de historia natural

versión impresa ISSN 0716-078X

Rev. chil. hist. nat. v.73 n.1 Santiago mar. 2000

http://dx.doi.org/10.4067/S0716-078X2000000100010 

Pseudoterranova cattani sp. nov. (Ascaridoidea: Anisakidae), a parasite
of the South American sea lion Otaria byronia De Blainville from Chile

Pseudoterranova cattani sp. nov. (Ascaridoidea: Anisakidae), un parásito
del lobo marino común Otaria byronia De Blainville en Chile

MARIO GEORGE-NASCIMENTO & XIMENA URRUTIA

Facultad de Ciencias, Universidad Católica de la Santísima Concepción, casilla 297, Concepción, Chile,
e-mail: mgeorgen@david.ucsc.cl

ABSTRACT

The parasitic nematode Pseudoterranova cattani sp. nov. is described from the stomach of the South American sea lion Otaria byronia De Blainville, sampled along the coastline off central-south Chile, between 1980 and 1997. The adult and larvae of this species have been previously reported in the Southeastern Pacific Ocean as Phocanema decipiens Myers. Major differences with species from the North Atlantic and Northwest Pacific are based on the body size, number, distance and size of caudal pillae.

Key words: Ascaridoidea, Anisakidae, new species, Pseudoterranova, Otaria byronia, South American sea lion, Chile.

RESUMEN

Se describe al nemátodo parásito Pseudoterranova cattani sp. nov. encontrado en el estómago del lobo marino común Otaria byronia De Blainville, en muestras tomadas entre 1980 y 1997, a lo largo de la costa del centro-sur de Chile. Las larvas y adultos de esta especie han sido registrados en el océano Pacífico sudoriental como Phocanema decipiens Myers. Las principales diferencias con las especies del Atlántico norte y del Pacífico noroccidental se basan en el tamaño corporal y en el número, tamaño, distancia y proporciones de las papilas caudales.

Palabras clave: Ascaridoidea, Anisakidae, especie nueva, Pseudoterranova, Otaria byronia, lobo marino común, Chile.

INTRODUCTION

The codworm Pseudoterranova decipiens (Krabbe 1878) was formerly believed to be a worldwide distributed species. However, it is already known that is a species complex composed by at least five species, with minimal morphological and clearcut genetic differentiation (Di Deco et al. 1994, Mattiucci et al. 1998, Paggi et al. 1991, 1998). The only taxonomic study on Pseudoterranova in the Southern Pacific is the redescription of P. decipiens s. l. in Otaria flavescens Shaw (= O. byronia De Blainville, see Oliva 1988) (Cattan & Carvajal 1980). These authors mentioned the difficulty in distinguishing species and described the morphometry and general arrangement of caudal papillae. They were able to discern on the shape of the caudal end of the spicule in adult males, but not on the detailed distances and ratios between the caudal papillae. SEM of in vitro cultured P. decipiens s.l. cephalic region with lips denticle distribution, and caudal region showing spicules, post anal plates and post anal papillae have been published (Carvajal et al. 1981). In the southeastern Pacific Ocean, off the Chilean coastline, allozymic and morphometric analyses revealed an undescribed Pseudoterranova species that was found as the adult stage in the South American sea lion O. byronia, and also as larvae in several fish prey species (George-Nascimento & Llanos 1995).

We describe herein this nematode and name it Pseudoterranova cattani sp. nov. in the honor of Dr. Pedro E. Cattan, Universidad de Chile, who was the first to report and study the taxonomy of this parasite in Chile.

MATERIAL AND METHODS

Between 1980 and 1997, fifty five specimens of the South American sea lion were sampled between Cobquecura and Chiloé (between ca. 36 and 39º S), Chile, and examined for nematodes. Fifteen Pseudoterranova males and 15 females were examined for each morphometric variable from the material recovered. They were cleared in Amman's lactophenol for light microscopic examination. Scanning electron microscopy was also used for the observation of cephalic and caudal structures. Measurements of internal organs were accomplished after dissection and observation by stereomicroscope. The morphometry and morphology were compared to descriptions given by Cattan & Carvajal (1980), Di Deco et al. (1994), and Mattiucci et al. (1998). Type specimens were deposited at Museo Nacional de Historia Natural, Santiago, Chile. Holotype: MNHN Nem Nº 11.167, Paratypes: Nem Nº 11.168.

RESULTS

Description

Pseudoterranova cattani sp. nov. (Figs. 1- 2, Tables 1- 2)


Fig. 1. Pseudoterranova cattani. 1: head, frontal view (100 µm), 2: Denticle ridge in the lips (10 µm), 3: lip papilla (10 µm), 4: excretory pore (10 µm), 5: male tail (100 µm), 6: Postcloacal papillae (100 µm), Codes of papillae as in Table 1, s= spicule.

Pseudoterranova cattani. 1: cabeza, vista frontal (100 µm), 2: Borde de dentículos en los labios (10 µm), 3: papila labial (10 µm), 4: poro excretor (10 µm), 5: cola del macho (100 µm), 6: Papilas postcloacales (100 µm), Códigos de papilas como en Tabla 1, s= espícula.


Fig. 2. Pseudoterranova cattani. 1: Dorsal view of head (200 µm), 2: Anterior part of body, lateral view (800 µm), 3: Male posterior end showing espicules, lateral view (300 µm), 4: Spicule (10µm) and schematic representation of the arrangement of caudal papillae in adult males (100 µm).

Pseudoterranova cattani. 1: Vista dorsal de la cabeza (200 µm), 2: Parte anterior del cuerpo, vista lateral (800 µm), 3: Extremo caudal del macho mostrando las espículas, vista lateral (300 µm), 4: Espícula (10µm) y representación esquemática de la disposición de las papilas caudales en machos adultos (100 µm).

General description: An Anisakidae with elongate large body, cuticular ridges from neck to tail, three prominent bilobed lips, one dorsal, with a wider base than the two subventral lips, and with the presence of two egg-shaped papillae, while subventral lips harbored one papilla each. Each lip with row of denticles located at its internal anterior fringe, interlabia and teeth absent, small cervical expansions of cuticle (wings), cervical deirids, one in front of the other, posterior to the neck. Excretory pore opening between the subventral lips. Compound esophagus with ventriculus and intestinal caecum anteriorly extended. No ventricular appendix. Nerve ring located in the anterior region of the esophagus. Presence of sexual dimorphism, with females larger in body size than males.

Males: Size smaller than females in length and width, with curvature in the form of a hook at the posterior end. Preanal papillae arranged in two lateral lines; two pairs of proximal post anal papillae. Subequal spicules, long and thin, ensheated, more expanded in its proximal end, lance-shaped, without accesory pieces, scarcely developed cuticular wings, three denticular chains located posterior to the cloaca. For morphometrics see Table 1.


Females: Presence of a prominent vulva normally located near the middle of the body. Deirids and nerve ring are at a larger distance from anterior end than in males. Muscular esophagus, ventriculus, intestinal caecum and the distance anus to tail are greater than in males. Vagina slim, long and followed by a straight uterus with two parts well defined (a single body and two horns). For morphometrics see Table 1.

DISCUSSION

Four out of 5 species already described within P. decipiens (A to D) have morphometric descriptions based on the size, distance and ratios between postanal papillae (Table 2). Names of 2 of these species have been proposed: Pseudoterranova bulbosa for P. decipiens C, Pseudoterranova azarasi for P. decipiens D, Mattiucci et al. 1998). No such a comparison can be made with Pseudoterranova decipiens E, because there is no morphological description yet for this Antarctic species (see Bullini et al. 1994).


Major differences between Pseudoterranova cattani sp. nov. and Pseudoterranova decipiens A, B, P. bulbosa and P. azarasi are the smaller mensural values than in P. cattani of: the length of spicules, the diameter of proximal papillae p and p', paracloacal papilla pc and distal papilla d1, the distance between the posterior papilla and d1, between the distal papilla d1 and d2, between papillae d3 and d4, and the body width at the level of paracloacal papilla pc. Moreover, a major characteristic that is useful to distinguish P. cattani from the other species in the complex the presence of two proximal papillae (p and p') located beneath the anus and pc, the paracloacal papillae (Table 2).

Pseudoterranova cattani has been reported at larval stage in several fish species in this area (George-Nascimento & Llanos 1995). The Juan Fernández fur seal Arctocephalus philippii (Peters) and the South American fur seal Arctocephalus australis Zimmerman are the only other potential hosts for this parasite, although the suitability of these species as definitive hosts for P. cattani is yet to be shown (see Sepúlveda & Alcaíno 1993).

(Received May 28, 1999; accepted September 27, 1999; managed by F. P. Ojeda)

ACKNOWLEDGMENTS

We are grateful to many people at different stages along time. This study was funded partially through Grants INB-029B, DIUC 98/80, FONDECYT 226/88, and from FONDAP O & B M, Programa Mayor 3, while preparing the manuscript.

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