Capsaloides istiophori Yamaguti, 1968

Chisholm, Leslie A. & Whittington, Ian D., 2006, Revision of Capsaloides (Monogenea: Capsalidae) with a redescription of C. magnaspinosus Price, 1939 from the nasal tissue of Tetrapterus audax (Istiophoridae) collected off Nelson Bay, New South Wales, Australia, Zootaxa 1160, pp. 1-20 : 9

Capsaloides istiophori Yamaguti, 1968 ( Figs 3 A, 4A, 4B)

Type­host: Istiophorus platypterus (Shaw, 1792) (Istiophoridae) . The type­host was originally recorded as I. orientalis (Temminck & Schlegel, 1844) which is now considered a synonym of I. platypterus (see Froese & Pauly 2005).

Type­locality: Hawaii, USA [Pacific Ocean].

Additional records: Tetrapterus audax (Philippi, 1997) , Hawaii, USA [Pacific Ocean] (see Yamaguti 1968); Istiophorus platypterus and Makaira indica (Cuvier, 1832) , from Cape Bowling Green, off Townsville and Cape Moreton, off Brisbane, Queensland, Australia [Pacific Ocean] (see Speare 1994, 1999).

Site: Gills.

Specimens examined: Holotype (USNPC 63598); 1 voucher (QM G212195).

Remarks

Yamaguti (1968) stated that this species differed from the closely related C. tetrapteri because the “posterior sinus” of the body and the isolated group of anterior dorsomarginal body sclerites was better developed in C. istiophori . We are unclear what “better developed” means, but the depth of the “posterior sinus” is a plastic character which is highly dependent on the method of flattening and state of contraction of the parasite. There are a greater number of dorsomarginal body sclerites in the left isolated anterior group of C. istiophori (14 sclerites comprising 5–7 cusps) than in C. tetrapteri (3–5 sclerites comprising 5–7 cusps). However, we have found that the number of sclerites in the anterior isolated group varies between parasites of different sizes (see Remarks for C. tetrapteri ) and therefore this character is likely uninformative when comparing parasites of different sizes/developmental stages. There are 10 bi­ or tricuspid dorsomarginal body sclerites in the right anterior isolated group of C. istiophori and only 0–4 in C. tetrapteri . The holotype of C. istiophori is much larger than the holotype and paratypes of C. tetrapteri and we consider that the larger number of sclerites may be a developmental difference rather than an indicator of species differences. The number of cusps associated with the dorsomarginal body sclerites decreases posteriorly ( Fig. 3 A) and the body sclerites end in the posterior third of the body which is also the case for C. tetrapteri ( Fig. 3 D). The haptoral accessory sclerites we examined in the holotype of C. istiophori ( Fig. 4 B) are slightly different from those illustrated by Yamaguti (1968) apparently from a paratype ( Fig. 4 A). This demonstrates that the morphology of the haptoral accessory sclerites likely varies between specimens of different sizes and may represent continual growth throughout parasite life (e.g. Kearn 1990). Nevertheless, the haptoral accessory sclerites of C. istiophori ( Figs 4 A, 4B) are similar morphologically to those of C. tetrapteri ( Fig. 4 E). Therefore we could find no clear characters to separate C. istiophori from C. tetrapteri . Because we consider C. tetrapteri to be synonymous with C. perugiai (see Remarks of C. tetrapteri and C. perugiai ), C istiophori is also, therefore, a synonym of C. perugiai .

Figures

FIGURE 3. Variation in the morphology of the dorsomarginal body sclerites of Capsaloides perugiai and those species (C. istiophori, C. marielenae and C. tetrapteri) newly synonymised with C. perugiai (present study). Note that the number of cusps associated with the crown­shaped sclerite decrease towards the posterior body region. A. C. istiophori, drawn from USNPC 63598. B. C. marielenae, drawn from CNHE 0 0 0 133. C. C. perugiai, redrawn from Setti (1898). D. C. tetrapteri, drawn from USNPC 63600. Scale bar: 10 m.

FIGURE 4. Haptoral accessory sclerites of Capsaloides perugiai and those species newly synonymised with C. perugiai. A. C. istiophori, redrawn from Yamaguti (1968). B. C. istiophori, drawn from USNPC 63598. C. C. marielenae, drawn from CNHE 0 0 0 133. D. C. perugiai, redrawn from Setti (1898). D. C. tetrapteri, drawn from USNPC 63600. Note that the only specimen of C. istiophori deposited is large and the morphology of the accessory sclerites are slightly different (B) to that drawn by Yamaguti (1968) (see A) who based his description on 28 specimens. Scale bar: 50 m.