New host and locality records for Tetrameres (Gynaecophila) spirospiculum Pinto & Vicente, 1995 (Nematoda: Tetrameridae), with new morphological data

SHORT COMMUNICATION

New Host and Locality Records for Tetrameres (Gynaecophila) spirospiculum Pinto & Vicente, 1995 (Nematoda: Tetrameridae), with New Morphological Data

Vol. 96(3) : 339-341, April 2001

María Celina Digiani/⁺, Florencia Cremonte*

Departamento Zoología Invertebrados, Museo de La Plata, Paseo del Bosque s/n, (1900) La Plata, Argentina *Centro de Estudios Parasitológicos y de Vectores, (1900) La Plata, Argentina

We report the finding of Tetrameres spirospiculum Pinto & Vicente, 1995 from Theristicus melanopis melanopis (Threskiornithidae) from Patagonia, Argentina. These constitute new host and locality records. We propose the assignation of this species to the subgenus T. (Gynaecophila) Gubanov, 1950, based on the presence of labia and the absence of cuticular flanges at the anterior end. Some new morphological data are provided, such as the arrangement of cuticular spines and the presence of a pair of somatic papillae at beginning of posterior third of body length. T. (G.) spirospiculum may probably be regarded as specific to birds of the genus Theristicus.

Key words: Tetrameres (Gynaecophila) spirospiculum - Nematoda - Theristicus melanopis melanopis - Threskiornithidae - Patagonia - Argentina

Tetrameres (Tetrameres) spirospiculum Pinto & Vicente, 1995 (Nematoda: Tetrameridae) was described from specimens collected from the proventriculus of Theristicus caudatus caudatus (Boddaert) (Aves: Threskiornithidae) from the State of Mato Grosso do Sul, Brazil (Pinto & Vicente 1995). This is one of the numerous species of Tetrameres (Creplin, 1846) reported from Brazilian birds (Vicente et al. 1995). Conversely, there are few reports of Tetrameres spp. from Argentina: T. (T.) tinamicola Pence, Mollhagen & Prestwood, 1975 from Eudromia elegans Geoffroy (Tinamidae) (Pence et al. 1975), T. (Gynaecophila) aspicula Digiani, 2000 from Plegadis chihi (Vieillot) (Threskiornithidae) (Digiani 2000), and T. (T.) megaphasmidiata Cremonte, Digiani, Bala & Navone, 2001 from Charadrius falklandicus Latham (Charadriidae) and Calidris fuscicollis Vieillot (Scolopacidae) (Cremonte et al. 2001).

The aim of this communication is to report the finding of T. spirospiculum in Theristicus melanopis melanopis (Gmelin) (Threskiornithidae) (new host record) from Patagonia, Argentina (new locality record). Moreover, we propose a different subgeneric assignation to the species based on cephalic structures, and provide some morphological details observed (under light and scanning electron microscopes).

In January 2000, two specimens of T. m. melanopis were found dead at Rahue (39°21´S-70°55´W), in the province of Neuquén, Patagonia, Argentina. After dissection, the digestive tract was fixed in the field with 10% formalin. From the proventriculus of one of the birds two adult worms were recovered, preserved in 70% alcohol and cleared in glycerine-alcohol for examination. Both specimens were identified as males of T. spirospiculum. Paratypes and voucher specimens of T. spirospiculum from the Helminthological Collection of the Instituto Oswaldo Cruz (CHIOC), Rio de Janeiro, Brazil, were examined with comparative purposes. One of our specimens and one voucher from CHIOC were dehydrated in an acetone series, dried by the critical point technique, coated with gold and examined under a JEOL JSM T100 scanning electron microscope (SEM). Classification of the nematodes regarding subgeneric diagnosis follows that proposed by Mollhagen (1976). Sensitive papilliform structures located posteriorly to deirids were referred to as somatic papillae following Digiani (2000) and Cremonte et al. (2001). Taxonomic status and nomenclature of the hosts follow Matheu and del Hoyo (1992).

Morphological characters and measurements (in micrometers) for each of our two specimens, separated by commas, are as follows: cuticle with fine transverse striations. Lateral alae absent. Total length 4050, 6090; maximum width 125,130. Mouth surrounded by two lateral crescent-shaped pseudolabia and dorsal and ventral labia (Fig. 1). Three bifid, blunt teeth are present on each pseudolabia (Fig. 1). Buccal capsule 17, 22 long; 13, 21 wide. Muscular oesophagus 282, 270; glandular oesophagus 742, 840 long. Nerve ring and excretory pore at 170, 190 and 211, 247 from anterior end, respectively. Deirids simple 128, 138 from anterior end. Cuticular spines in two subventral rows, arising at about midbody, ending in front of the cloaca. Spines minute, 2-4 long, arranged in diagonally aligned pairs (Fig. 2) at a distance of 120-190 at midbody and gradually diminishing towards posterior extremity (15-67). Pair of somatic papillae at beginning of posterior third of body length, only seen with SEM (Fig. 3, photograph corresponding to voucher specimen from CHIOC). Left spicule 1015, 930 long; straight portion 465, 448; loosely twisted portion 200, 242; tightly twisted portion 350, 240 long. Right spicule 145, 157 long. Tail 16, 15 in length. Some rounded adanal papillae (at least four, exact number could not be established), only seen with SEM (Fig. 4).

Figures 1-4

Specimens are deposited in the Helmin-thological Collection of the Museo de La Plata (no. 4600/2), La Plata, Argentina.

Morphology and dimensions of the Argentine specimens of T. spirospiculum closely conform to the original description (Pinto & Vicente 1995). There are, however, some differences concerning the interpretation of the cephalic structures. Both specimens from Brazil and Argentina were found to possess dorsal and ventral labia (Fig. 1). Labia are stated as absent in the text of the original description and consequently not figured in the apical view drawing (Pinto & Vicente 1995: fig. 1d, p. 616), although they are clearly seen in the lateral view drawing (Fig. 1a, p. 616).

Authorities of T. spirospiculum followed the subgeneric classification by Chabaud (1975), who proposed the subgenera, T. (Tetrameres) Creplin, 1846 and T. (Microtetrameres) Travassos, 1915, mainly based on the female body shape and the presence or absence of spines in males. However, a later classification proposed by Mollhagen (1976) and adopted by many other authors (Mawson 1979, Bergan et al. 1994, Digiani 2000, Cremonte et al. 2001), considers Microtetrameres as a separate genus and recognises three subgenera of Te-trameres based upon the presence or absence of dorsal and ventral labia and lateral cuticular flanges at the cephalic end. According to this, we suggest T. spirospiculum Pinto & Vicente, 1995 to be included in the subgenus T. (Gynaecophila) Gubanov, 1950 in the light of the presence of labia and the absence of cuticular flanges at the anterior end.

The two host subspecies recorded hitherto for this nematode are alopatric, indicating that the parasite is present in a wide geographical range from Mato Grosso do Sul to northern Patagonia. It would be desirable to confirm this distribution range by examining Theristicus spp. from the province of Buenos Aires (Argentina), an intermediate region between southern Brazil and southern Argentina. Another threskiornithid bird present in the mentioned area is Plegadis chihi (Vieillot), which in some environmental conditions, overlaps in its food habits with Theristicus spp., thus becoming a potential host for T. (G.) spirospiculum. However, Digiani (1999) never found this species in an extensively surveyed population of P. chihi (n=86) in the province of Buenos Aires and thus, T. (G.) spirospiculum may probably be regarded as specific to birds of the genus Theristicus Wagler.

ACKNOWLEDGEMENTS

To Luis C Muniz-Pereira (CHIOC) for the loan of specimens of T. spirospiculum, to the staff of the Servicio de Microscopía Electrónica de Barrrido (Museo de La Plata) for their technical assistance, to Lucy Shirlaw for revision of English, and to Darío Podestá, Sebastián Cirignoli and Ulyses Pardiñas for help in the field work.

REFERENCES

Figs.1-4

• Bergan JF, Radomski AA, Pence DB, Rhodes OE 1994. Tetrameres (Petrowimeres) striata in ducks. J Wild Dis 30: 351-358.
• Chabaud AG 1975. Keys to the genera of the order Spirurida. Spiruroidea, Habronematoidea and Acuarioidea. In RC Anderson, AG Chabaud, S Willmott (eds), CIH Keys to the Nematode Parasites of Vertebrates 3, Part 2, Commonwealth Agricultural Bureaux, England, p. 29-58.
• Cremonte F, Digiani MC, Bala LOB, Navone GT 2001. Tetrameres (Tetrameres) megaphasmidiata n. sp. (Nematoda: Tetrameridae) a parasite of the two-banded plover, Charadrius falklandicus, and white-rumped sandpiper, Calidris fuscicollis, from Patagonia, Argentina. J Parasitol 87 (in press).
• Digiani MC 1999. Estudios Helmintológicos en Aves Limnícolas del Litoral Rioplatense, PhD Thesis, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Argentina, 148 pp.
• Digiani MC 2000. Tetrameres (Gynaecophila) aspicula n. sp. (Nematoda: Tetrameridae), a proventricular parasite of the white-faced ibis Plegadis chihi in Argentina. Syst Parasitol 47: 111-117.
• Matheu A, del Hoyo J 1992. Family Threskiornithidae. In J del Hoyo, A Elliott, J Sargatal (eds), Handbook of the Birds of the World 1, Lynx Edicions, Barcelona, p. 472-506.
• Mawson PM 1979. Some Tetrameridae (Nematoda: Spirurida) from Australian birds. Trans Royal Soc South Australia 103: 177-184.
• Mollhagen TR 1976. A Study of the Systematics and Hosts of the Parasitic Nematode Genus Tetrameres (Habronematoidea: Tetrameridae), PhD Thesis, Texas Tech University, Lubbock, Texas, 546 pp.
• Pence DB, Mollhagen TR, Prestwood AK 1975. Tetrameres (Tetrameres) tinamicola sp. n. from the crested tinamou, Eudromia elegans, with comments on the subgenus Petrowimeres (Nematoda: Tetrameridae). J Parasitol 61: 825-829.
• Pinto RM, Vicente JJ 1995. Tetrameres (Tetrameres) spirospiculum n. sp. (Nematoda: Tetrameridae) from the buff-necked ibis, Theristicus caudatus caudatus (Boddaert) (Aves, Threskiornithidae). Mem Inst Oswaldo Cruz 90: 615-617.
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Publication Dates

• Publication in this collection
  11 Apr 2001
• Date of issue
  Apr 2001

History

• Accepted
  18 Sept 2000
• Received
  27 June 2000