Gyrodactylus costaricensis Kritsky & Fritts 1970

Gyrodactylus costaricensis Kritsky & Fritts, 1970

(Figure 6; Tables 4 and 7)

Type host: Poecilia sphenops Valenciennes (“Mexican molly”, “topote mexicano”).

Site of infection: Body surface.

Type locality: Rincón, Puntarenas Province, Costa Rica.

Type material examined: Three paratypes (USNPC 1181–7, 1181–10 and 1181–15).

Comments: The measurements obtained from the re-assessment of three paratypes of G. costaricensis, given in Table 4, concur with those given by Kritsky & Fritts (1970) and Harris & Cable (2000) presented in Table 7. The apparent disparity in the measurements of the ventral bar total length and width, however, result from two opposing approaches regarding the measurement of these structures. The total length of the ventral bar as it is described in Malmberg (1970), is a width measurement with respect to the longitudinal axis of the worm; the measurement of this feature as presented in Shinn et al. (2004) follows the longitudinal axis of the worm. With this in mind, however, there is good agreement between accounts as to the overall dimensions of the ventral bar. The only minor discrepancy between records relates to the length of the marginal hook sickle which ranges from 5.5 (Harris & Cable 2000), through 6.2–6.7 (current study) to 7–8 (Kritsky & Fritts 1970). The additional morphometric variables on the haptoral skeletal elements, as proposed by Shinn et al. (2004), are given in Table 4. No MCO was observed on the three paratypes examined for the current study.

The marginal hook sickle base of G. costaricensis is approximately triangular and deep, representing approximately half the length of the sickle. The heel is rounded; the toe triangular, the underside of which is level with the underside of the heel. The toe bridge is small. The sickle shaft is proportionately narrow and terminates in a short tip. The marginal hooks of both G. j a ro c h o sp. nov. and G. xalapensis sp. nov. can be readily discriminated from those of G. costaricensis by virtue of the smooth curved shaft and point region and proportionately long sickle points (Figures 7, 8). The marginal hooks sickles of G. costaricensis and Gyrodactylus poeciliae Harris & Cable, 2000 are similar in that both have proportionately slender sickle points with short tips and deep sickle bases with triangular toes. The toe of G. poeciliae, however, is proportionately much longer, the bridge of which does not slope as sharply as that of G. costaricensis.