Goffartia heteroceri Hirschmann, 1952

Tahseen, Qudsia & Mustaqim, Malka, 2015, A taxonomic review of the genus Goffartia Hirschmann, 1952 (Rhabditida: Diplogastridae) with a note on the relationship of congeners, Zootaxa 4034 (1) : -

Goffartia heteroceri Hirschmann, 1952

( Figs. 1 C, 2B, 3C, 6)

Measurements. Table 1,

Description. Adult: Body medium- to large-sized, between 0.7–1 mm in length. Cuticle smooth under LM, without transverse and longitudinal striations. Lateral fields demarcated. Lip region low, rounded to dome-shaped; continuous with the adjoining body; lips fused; labial sensilla slightly raised. Amphidial apertures transversely oval, located at three-fourths of lip width from anterior end. Cheilostom long, cuticularised with diverging anterior and posterior ends; gymnostom and stegostom forming barrel-shaped buccal cavity; gymnostom arched; metastegostom without tooth; a single stomal ring partially proximally inserted into the pharynx. Pharyngeal collar almost one-fourth of stoma length, dorsally extending slightly into pharynx. Pharyngeal corpus muscular, median bulb strongly developed with ‘almond-shaped’ valve plates; anterior pharyngeal part equal to or longer than posterior part; basal bulb oval in shape, well demarcated from isthmus. Nerve ring not shown in the original illustration; secretory-excretory pore not discernible. Tail very long, narrowing into hair-like terminal part.

Female: Reproductive system didelphic, amphidelphic with both genital branches symmetrical and largely equal. Vulva pre-equatorial. Uteri occasionally with a pair of eggs.

Male: Similar to female in other morphological characters except being smaller. Reproductive system monorchic with a reflexed testis. Tail divided into an anterior conical part and an abruptly narrowing cylindrical part terminating in a whip. Genital papillae 9 pairs with two precloacal and seven postcloacal pairs with a configuration of v1 + v2 / v3 d, v4,ad, (v5 + v6, v7), pd. The genital pairs v1 + v2 are relatively close, subventral; v3 d at the level of cloaca, lateroventral; v4 subventral; ad lateral; v5 and v6 subventral closer than v7; pd subdorsal. Phasmids located between ad and v5. Spicules strong, falcate, about as long as cloacal body diameter, gubernaculum strong, trough-shaped with attenuated proximal end; about 40% of the spicule length. Tail long, filiform narrowing into hair-like terminal part.

Locality and habitat. Goffartia heteroceri has been reported from thermal spring ( Meyl 1953, 1954) and potable water ( Zullini 1981, 1982; Volterra et al. 1999; associated with Heterocerus Fabricius, 1792 beetles in littoral habitats. The species has been found in Europe ( Germany, Hungary, Lithuania) and is widespread in Italy, especially in the central regions of the peninsula ( Zullini,1982).

G. heteroceri lives phoretically on the heterocerid water beetles Heterocerus fenestratus Thunberg, 1784 , H. fusculus Kiesenwetter, 1843 and H. marginatus Fabricius, 1787 and also colonizes Stenolophus teutonus Schrank, 1781 (Carabidae) and Paederus riparius Linnaeus, 1758 (Staphylinidae) . The species is transported by the insect host to new aquatic habitats as the diapausing larvae overwinter in the host body between the folds of abdominal segments ( Steffan 1967).

Salient characters. The species is characterised by smooth cuticle without transverse and longitudinal striations; lateral fields demarcated; lip region low, rounded to dome-shaped; labial sensilla slightly raised. Amphidial apertures transversely oval, about one-fourth of the corresponding body diameter, or about stoma width; stoma barrel-shaped, unarmed with single ring; pharyngeal corpus having thick lumen and strongly built median bulb; anterior pharyngeal part equal to or longer than posterior part; both genital branches of female gonad almost equal; males with cephalated, arcuate and falcate spicules; gubernaculum 40–50% of the spicule length, troughshaped with tapering proximal and distal ends and genital papillae v5 and v6 closely placed and slightly distant from v7.

Figures

FIGURE 1. Anterior body ends. A: Goffartia africana. B: G. filicaudata. C: G. heteroceri. D: G. variabilis. E: G. praepilata. F: G. phalacra. G: Female reproductive system in Goffartia sp. (Scale bar = 10 µm).